Harminder Singh, M.D.

All Publications

• A Dual Approach for the Management of Complex Craniovertebral Junction Abnormalities: Endoscopic Endonasal Odontoidectomy and Posterior Decompression with Fusion. World neurosurgery: X Alalade, A. F., Ogando-Rivas, E., Forbes, J., Ottenhausen, M., Uribe-Cardenas, R., Hussain, I., Nair, P., Lehner, K., Singh, H., Kacker, A., Anand, V. K., Hartl, R., Baaj, A., Schwartz, T. H., Greenfield, J. P. 2019; 2: 100010

  Abstract

  Background: Ventral brainstem compression secondary to complex craniovertebral junction abnormality is an infrequent cause of neurologic deterioration in pediatric patients. However, in cases of symptomatic, irreducible ventral compression, 360° decompression of the brainstem supported by posterior stabilization may provide the best opportunity for improvement in symptoms. More recently, the endoscopic endonasal corridor has been proposed as an alternative method of odontoidectomy associated with less morbidity. We report the largest single case series of pediatric patients using this dual-intervention surgical technique. The purpose of this study was to evaluate the surgical outcomes of pediatric patients who underwent posterior occipitocervical decompression and instrumentation followed by endoscopic endonasal odontoidectomy performed to relieve neurologic impingement involving the ventral brainstem and craniocervical junction.Methods: Between January 2011 and February 2017, 7 patients underwent posterior instrumented fusion followed by endonasal endoscopic odontoidectomy at our unit. Standardized clinical and radiological parameters were assessed before and after surgery. A univariate analysis was performed to assess clinical and radiologic improvement after surgery.Results: A total of 14 operations were performed on 7 pediatric patients. One patient had Ehlers-Danlos syndrome, 1 patient had a Chiari 1 malformation, and the remaining 5 patients had Chiari 1.5 malformations. Average extubation day was postoperative day 0.9. Average day of initiation of postoperative feeds was postoperative day 1.0.Conclusions: The combined endoscopic endonasal odontoidectomy and posterior decompression and fusion for complex craniovertebral compression is a safe and effective procedure that appears to be well tolerated in the pediatric population.

  View details for DOI 10.1016/j.wnsx.2019.100010

  View details for PubMedID 31218285

• Patient Positioning and Operating Room Setup Pediatric Endoscopic Endonasal Skull Base Surgery Dayani, F., Medress, Z., Anand, V. K., Schwartz, T. H., Singh, H. Thieme. 2019; 1
• Pediatric Endoscopic Endonasal Skull Base Surgery Schwartz, T. H. edited by Singh, H., Greenfield, J. P., Anand, V. K. Thieme. 2019
• Craniopharyngioma Pediatric Endoscopic Endonasal Skull Base Surgery Singh, H., Essayed, W. I., Schwartz, T. H. Thieme. 2019; 1
• Meningoencephaloceles Pediatric Endoscopic Endonasal Skull Base Surgery Zeinalizadeh, M., Sadrhosseini, S. M., da Silva, H. B., Singh, H. Thieme. 2019; 1
• Closure Techniques for the Pediatric Skull Base: Gasket Seal Pediatric Endoscopic Endonasal Skull Base Surgery Singh, H., Anand, V. K., Schwartz, T. H. Thieme. 2019; 1
• Instrumentation Pediatric Endoscopic Endonasal Skull Base Surgery. Essayed, W. I., Radhouane, K., Schwartz, T. H., Singh, H. Thieme. 2019; 1
• Endonasal Corridors and Approaches Pediatric Endoscopic Endonasal Skull Base Surgery Singh, H., Greenfield, J. P., Almodovar, G. J., Anand, V. K., Schwartz, T. H. Thieme. 2019; 1
• Odontoidectomy for Cranio-Vertebral Junction Compression Pediatric Endoscopic Endonasal Skull Base Surgery Singh, H., Alalade, A., Greenfield, J. P., Anand, V. K., Schwartz, T. H. Thieme. 2019; 1
• Ventral Approaches to Intraparenchymal Tumors of the Skull-base and Brainstem Pediatric Endoscopic Endonasal Skull Base Surgery Singh, H., Ho, A., Kim, L., Essayed, W. I., Schwartz, T. H. Thieme. 2019; 1
• Lumbar Puncture for the Injection of Intrathecal Fluorescein: Should It Be Avoided in a Subset of Patients Undergoing Endoscopic Endonasal Resection of Sellar and Parasellar Lesions? Journal of neurological surgery. Part B, Skull base Zhang, M., Azad, T. D., Singh, H., Salam, S., Jain, S., Anand, V. K., Schwartz, T. H. 2018; 79 (6): 554?58

  Abstract

  Objectives The use of intrathecal fluorescein (ITF) has become an increasingly adopted practice for the identification of cerebrospinal fluid (CSF) leaks during endoscopic skull base surgery for pituitary adenomas. Administration through lumbar puncture can result in postoperative positional headaches, increasing morbidity, cost, and length of stay. We sought to identify the incidence of and variables associated with postoperative headaches to determine if there was a subgroup of patients in whom this procedure should be avoided. Methods We conducted a retrospective single-institution review of 148 patients who underwent endoscopic resection with ITF for pituitary adenoma between December 2003 and February 2016. We excluded patients who had lumbar drains and with intraoperative CSF leak, as these patients may have other headache etiologies. Patient demographics, comorbidities, tumor features, surgical approach, surgical closure, and histology were recorded. Primary outcomes included the presence of postoperative and positional headaches. Results We identified 62 patients with postoperative headaches (41.9%) and 10 with positional headaches (6.8%), of whom 6 underwent blood patch with complete resolution. Following univariate analysis, there was a significant positive association with prolactin-secreting tumors ( p =0.008). There was a negative association with a history of hypertension ( p =0.0001) and age ( p =0.01). Following multivariate modeling, the significance for hypertension ( p =0.01) was preserved. Conclusions Positional headaches in patients who receive ITF are uncommon and should not limit its use in the preparations for endoscopic resection of pituitary adenomas. Avoiding ITF in younger patients without hypertension with prolactinomas might decrease the risk of post-ITF positional headaches.

  View details for DOI 10.1055/s-0038-1635257

  View details for PubMedID 30456024

• Landmarks to Identify Petrous Apex Through Endonasal Approach Without Transgression of Sinus. Journal of neurological surgery. Part B, Skull base Negm, H. M., Singh, H., Dhandapani, S., Cohen, S., Anand, V. K., Schwartz, T. H. 2018; 79 (2): 156?60

  Abstract

  Objectives ?The use of nasopharyngeal landmarks to localize the petrous apex has not been previously described. We describe a purely endoscopic endonasal corridor to localize the petrous apex without transgressing any of the paranasal sinuses. Methods ?Anatomical dissections of four formalin preserved cadaveric heads (eight petrous apices) were performed to evaluate the feasibility of a nonsinus-based approach and illustrate the surgical landmarks and measurements that are useful for surgery in this area. Results ?The Eustachian tubes, fossa of Rosenmüller (FR), and posterior end of the middle and inferior turbinates are constant landmarks, which can be identified without opening any nasal sinuses. The petrous apex is located on an extended straight line connecting the upper end of the torus tubarius (TT) and the roof of the FR. The distance from upper end of TT to the roof of FR measured 9.875 (±0.99) mm, and the distance from roof of the FR to the petrous apex measured 9.75 (±1) mm. Conclusion ?With well-defined landmarks, the inferior, medial petrous apex can be reached using the endoscopic endonasal approach without crossing the sinus cavities.

  View details for PubMedID 29868320

  View details for PubMedCentralID PMC5978856

• Minimally invasive lumbar pedicle screw fixation using cortical bone trajectory - Screw accuracy, complications, and learning curve in 100 screw placements. Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia Dayani, F., Chen, Y. R., Johnson, E., Deb, S., Wu, Y., Pham, L., Singh, H. 2018

  Abstract

  Cortical bone trajectory (CBT) is a novel pedicle insertion technique with comparable or superior mechanical properties and reduced invasiveness compared to traditional methods. We describe the screw accuracy, complications, and learning curve associated with CBT use. A prospective cohort study was performed involving 22 patients who underwent lumbar fusion with CBT screw placement. A total of 100 cortical screws were placed. Post-operative CT scans were reviewed to assess the adequacy of screw placement and calculate the incidence of vertebral body and pedicle breaches from cortical screw placement. Technique-related complications were examined. The entire surgical cohort was divided into two groups: early experience (first 11 patients) and late experience (last 11 patients), to study the effect of learning curve on CBT screw placement. Medial pedicle breach was observed in 6/100 cases and lateral vertebral body breach was observed in 1/100 cases. The incidence of durotomy related to the technique was 4.5% (N?=?1/22). Post-surgical wound infection was seen in 9.1% of patients (N?=?2/22). 66.7% (N?=?4/6) of medial pedicle breaches, 100% (N?=?1/1) of lateral breaches, 100% (N?=?1/1) of CBT technique-related CSF leaks, and 100% (N?=?2/2) of wound infections occurred in the early experience phase of our study (p?=?0.0945). A shift in surgical technique and greater efficiency over time decreased the incidence of overall complications in the late cohort. The difference, however, did not reach statistical significance. A lateralized starting point for the cortical screw on the pars interarticularis and use of smaller diameter screws resulted in fewer medial pedicle out-fractures and breaches.

  View details for PubMedID 30420203

• Basilar Artery Ectasia Causing Trigeminal Neuralgia: An Evolved Technique of Transpositional Suture-Pexy. Operative neurosurgery (Hagerstown, Md.) Singh, H., da Silva, H. B., Zeinalizadeh, M., Elarjani, T., Straus, D., Sekhar, L. N. 2018; 14 (2): 194?99

  Abstract

  Microvascular decompression for patients with trigeminal neuralgia (TGN) is widely accepted as one of the modalities of treatment. The standard approach has been retrosigmoid suboccipital craniotomy with placement of a Teflon pledget to cushion the trigeminal nerve from the offending artery, or cauterize and divide the offending vein(s). However, in cases of severe compression caused by a large artery, the standard decompression technique may not be effective.To describe a unique technique of vasculopexy of the ectatic basilar artery to the tentorium in a patient with TGN attributed to a severely ectatic and tortuous basilar artery. A case series of patients who underwent this technique of vasculopexy for arterial compression is presented.The patient underwent a subtemporal transtentorial approach and the basilar artery was mobilized away from the trigeminal nerve. A suture was then passed through the wall of the basilar artery (tunica media) and secured to the tentorial edge, to keep the artery away from the nerve.The neuralgia was promptly relieved after the operation, with no complications. A postoperative magnetic resonance imaging scan showed the basilar artery to be away from the trigeminal root. In a series of 7 patients who underwent this technique of vasculopexy, no arterial complications were noted at short- or long-term follow-up.Repositioning and vasculopexy of an ectatic basilar artery for the treatment of TGN is safe and effective. This technique can also be used for other neuropathies that result from direct arterial compression.

  View details for PubMedID 29351686

• Factors influencing outcome in patients with colloid cysts who present with acute neurological deterioration. Journal of clinical neuroscience : official journal of the Neurosurgical Society of Australasia Singh, H., Burhan Janjua, M., Ahmed, M., Esquenazi, Y., Dhandapani, S., Mauer, E., Schwartz, T. H., Souweidane, M. S. 2018

  Abstract

  Colloid cysts have been associated with acute neurologic deterioration and sudden death. However, the low incidence of associated sudden deaths has meant that factors influencing outcome in patients who present with acute neurological deterioration have not been extensively published. A PubMed literature search was performed to identify reported patients who presented with acute neurological deterioration with radiographic or histopathologic diagnosis of a colloid cyst. Demographic data, presenting symptoms, physical exam, surgical interventions, and outcomes were recorded. Analysis included 140 patients. Mean cyst size was 2.12?cm in males and 1.59?cm in females (p?=?0.155), and 1.64?cm in patients who survived and 2.05?cm in patients who died (p?=?0.04). Minimum cyst size was 0.4?cm in females and 0.8?cm in males. All patients without surgical intervention died, versus 48% with surgical intervention (p?

  View details for PubMedID 29907387

• Endoscopic Technology and Repair Techniques. Handbook of Neurology: Meningiomas. Singh, H., Essayed, W., Schwartz, T. Elsevier. 2018
• Cervical Stenosis in Adult Arthrogryposis: A Case Report and Review of the Literature. Journal of neurological surgery reports Ho, A. L., Mohole, J., Sussman, E. S., Pendharkar, A. V., Singh, H. 2018; 79 (1): e19?e22

  Abstract

  Arthrogryposis multiplex congenita is a rare, nonprogressive congenital disorder that describes a constellation of conditions characterized by multiple joint contractures. Spinal pathology and deformity are common; however, the majority of the literature on arthrogryposis is focused on pediatric management. There exist very few reports on long-term outcomes and management of adults with arthrogryposis. We present a case of cervical spinal stenosis in an adult female with arthrogryposis that underwent posterior cervical decompression and fusion. A review of spine-related sequelae seen in adults with arthrogryposis and considerations for spinal surgery for these patients is discussed.

  View details for PubMedID 29581933

  View details for PubMedCentralID PMC5860911

• Minimally Invasive Lumbar Pedicle Screw Fixation Using Cortical Bone Trajectory: Functional Outcomes. Cureus Chen, Y., Deb, S., Jabarkheel, R., Pham, L., Patel, M., Singh, H. 2018; 10 (10): e3462

  Abstract

  Background Pedicle screw fixation is currently the mainstay technique for lumbar spinal fusion; however, more minimally invasive techniques are available such as cortical screw fixation. Numerous studies have proven biomechanical equivalence or superiority for cortical screws but few studies have examined clinical outcomes in patients. Our study aims to examine functional outcomes, as well as fusion rates, in patients who underwent pedicle screw fixation using a cortical trajectory. Methods We retrospectively reviewed prospectively collected functional outcomes data on 10 patients with a degenerative lumbar disease who underwent cortical screw placement by the senior author. Oswestry Disability Index (ODI) and Roland Morris (RM) scoring were calculated preoperatively, at six to 12 weeks and at six to eight months. The Kruskal-Wallis test and Dunn's multiple comparison were used to analyze differences in scores over time. Results We found that over time, cortical screw fixation resulted in a mean decrease of 27 from the baseline ODI at six to eight months (p = 0.014). Additionally, six out of seven (86%) patients who had at least 12 months of radiographic follow-up showed fusion. Conclusions Cortical screw fixation showed a decrease of 27 from the baseline ODI at six to eight months, which is comparable to changes from the baseline ODI reported in three, recent, large clinical trials examining functional outcomes following traditional pedicle screw fixation.

  View details for PubMedID 30564541

• Endocrine Silent Pituitary Tumors Surgical Neuro-Oncology Singh, H., Salam, S., Schwartz, T. H. Oxford University Press. 2018; 1
• Anterior Skull Base Tumors ? Endoscopic Perspective Controversies in Neuroendoscopy Singh, H., Essayed, W. E., Schwartz, T. H. Thieme. 2018; 1
• Transbasal and Extended Subfrontal Bilateral Approach Operative Cranial Neurosurgical Anatomy Singh, H., Zeinalizadeh, M., Da-Silva, H., Sekhar, L. Thieme. 2018; 1
• Side-to-Side A3-A4 Bypass after Clip Ligation of Recurrent Coiled Anterior Communicating Artery Aneurysm: 3-Dimensional Operative Video. Operative neurosurgery (Hagerstown, Md.) Park, D. H., Singh, H., da Silva, H. B., Sekhar, L. N. 2018; 14 (1): 87

  View details for PubMedID 29253295

• Contralateral supraorbital keyhole approach to medial optic nerve lesions: an anatomoclinical study. Journal of neurosurgery Singh, H., Essayed, W. I., Jada, A., Moussazadeh, N., Dhandapani, S., Rote, S., Schwartz, T. H. 2017; 126 (3): 940-944

  Abstract

  OBJECTIVE The authors describe the supraorbital keyhole approach to the contralateral medial optic nerve and tract, both in a series of cadaveric dissections and in 2 patients. They also discuss the indications and contraindications for this procedure. METHODS In 3 cadaver heads, bilateral supraorbital keyhole minicraniotomies were performed to expose the ipsilateral and contralateral optic nerves. The extent of exposure of the medial optic nerve was assessed. In 2 patients, a contralateral supraorbital keyhole approach was used to remove pathology of the contralateral medial optic nerve and tract. RESULTS The supraorbital keyhole craniotomy provided better exposure of the contralateral superomedial nerve than it did of the same portion of the ipsilateral nerve. In both patients gross-total resections of the pathology was achieved. CONCLUSIONS The authors demonstrate the suitability of the contralateral supraorbital keyhole approach for lesions involving the superomedial optic nerve.

  View details for DOI 10.3171/2016.3.JNS1634

  View details for PubMedID 27257841

• Endonasal management of pediatric congenital transsphenoidal encephaloceles: nuances of a modified reconstruction technique. Technical note and report of 3 cases. Journal of neurosurgery. Pediatrics Zeinalizadeh, M., Sadrehosseini, S. M., Habibi, Z., Nejat, F., Silva, H. B., Singh, H. 2017; 19 (3): 312-318

  Abstract

  OBJECTIVE Congenital transsphenoidal encephaloceles are rare malformations, and their surgical treatment remains challenging. This paper reports 3 cases of transsphenoidal encephalocele in 8- to 24-month-old infants, who presented mainly with airway obstruction, respiratory distress, and failure to thrive. METHODS The authors discuss the surgical management of these lesions via a minimally invasive endoscopic endonasal approach, as compared with the traditional transcranial and transpalatal approaches. A unique endonasal management algorithm for these lesions is outlined. The lesions were repaired with no resection of the encephalocele sac, and the cranial base defects were reconstructed with titanium mesh plates and vascular nasoseptal flaps. RESULTS Reduction of the encephalocele and reconstruction of the skull base was successfully accomplished in all 3 cases, with favorable results. CONCLUSIONS The described endonasal management algorithm for congenital transsphenoidal encephaloceles is a safe, viable alternative to traditional transcranial and transpalatal approaches, and avoids much of the morbidity associated with these open techniques.

  View details for DOI 10.3171/2016.10.PEDS16270

  View details for PubMedID 28106514

• Minimally Invasive Robotic Laser Corpus Callosotomy: A Proof of Concept. Cureus Singh, H., Essayed, W. I., Deb, S., Hoffman, C., Schwartz, T. H. 2017; 9 (2)

  Abstract

  We describe the feasibility of using minimally invasive robotic laser interstitial thermotherapy (LITT) for achieving an anterior two-thirds as well as a complete corpus callosotomy.Ten probe trajectories were plotted on normal magentic resonance imaging (MRI) scans using the Brainlab Stereotactic Planning Software (Brainlab, Munich, Germany). The NeuroBlate® System (Monteris Medical, MN, USA) was used to conform the thermal burn to the corpus callosum along the trajectory of the probe. The distance of the ideal entry site from either the coronal suture and the torcula or nasion and the midline was calculated. The distance of the probe tip from the dorsal and ventral limits of the callosotomy in the sagittal plane were also calculated.Anterior two-thirds callosotomy was possible in all patients using a posterior parieto-occipital paramedian trajectory through the non-dominant lobe. The average entry point was 3.64 cm from the midline, 10.6 cm behind the coronal suture, and 9.2 cm above the torcula. The probe tip was an average of 1.4 cm from the anterior commissure. For a total callosotomy, an additional contralaterally placed frontal probe was used to target the posterior one-third of the corpus callosum. The average entry site was 3.3 cm from the midline and 9.1 cm above the nasion. The average distance of the probe tip from the base of the splenium was 0.94 cm.The directional thermoablation capability of the NeuroBlate® system allows for targeted lesioning of the corpus callosum, to achieve a two-thirds or complete corpus callosotomy. A laser distance of < 2 cm is sufficient to reach the entire corpus callosum through one trajectory for an anterior two-thirds callosotomy and two trajectories for a complete callosotomy.

  View details for DOI 10.7759/cureus.1021

  View details for PubMedID 28348940

  View details for PubMedCentralID PMC5346016

• Endoscopic endonasal versus microscopic transsphenoidal surgery for recurrent and/or residual pituitary adenomas. World neurosurgery Esquenazi, Y., Essayed, W. I., Singh, H., Mauer, E., Ahmed, M., Christos, P. J., Schwartz, T. H. 2017

  View details for DOI 10.1016/j.wneu.2017.01.110

  View details for PubMedID 28185971

• Endonasal endoscopic reoperation for residual or recurrent craniopharyngiomas JOURNAL OF NEUROSURGERY Dhandapani, S., Singh, H., Negm, H. M., Cohen, S., Souweidane, M. M., Greenfield, J. P., Anand, V. K., Schwartz, T. H. 2017; 126 (2): 418-430

  Abstract

  OBJECTIVE Craniopharyngiomas can be difficult to remove completely based on their intimate relationship with surrounding visual and endocrine structures. Reoperations are not uncommon but have been associated with higher rates of complications and lower extents of resection. So radiation is often offered as an alternative to reoperation. The endonasal endoscopic transsphenoidal approach has been used in recent years for craniopharyngiomas previously removed with craniotomy. The impact of this approach on reoperations has not been widely investigated. METHODS The authors reviewed a prospectively acquired database of endonasal endoscopic resections of craniopharyngiomas over 11 years at Weill Cornell Medical College, NewYork-Presbyterian Hospital, performed by the senior authors. Reoperations were separated from first operations. Pre- and postoperative visual and endocrine function, tumor size, body mass index (BMI), quality of life (QOL), extent of resection (EOR), impact of prior radiation, and complications were compared between groups. EOR was divided into gross-total resection (GTR, 100%), near-total resection (NTR, > 95%), and subtotal resection (STR, < 95%). Univariate and multivariate analyses were performed. RESULTS Of the total 57 endonasal surgical procedures, 22 (39%) were reoperations. First-time operations and reoperations did not differ in tumor volume, radiological configuration, or patients' BMI. Hypopituitarism and diabetes insipidus (DI) were more common before reoperations (82% and 55%, respectively) compared with first operations (60% and 8.6%, respectively; p < 0.001). For the 46 patients in whom GTR was intended, rates of GTR and GTR+NTR were not significantly different between first operations (90% and 97%, respectively) and reoperations (80% and 100%, respectively). For reoperations, prior radiation and larger tumor volume had lower rates of GTR. Vision improved equally in first operations (80%) compared with reoperations (73%). New anterior pituitary deficits were more common in first operations compared with reoperations (51% vs 23%, respectively; p = 0.08), while new DI was more common in reoperations compared with first-time operations (80% vs 47%, respectively; p = 0.08). Nonendocrine complications occurred in 2 (3.6%) first-time operations and no reoperations. Tumor regrowth occurred in 6 patients (11%) over a median follow-up of 46 months and was not different between first versus reoperations, but was associated with STR (33%) compared with GTR+NTR (4%; p = 0.02) and with not receiving radiation after STR (67% vs 22%; p = 0.08). The overall BMI increased significantly from 28.7 to 34.8 kg/m(2) over 10 years. Six months after surgery, there was a significant improvement in QOL, which was similar between first-time operations and reoperations, and negatively correlated with STR. CONCLUSIONS Endonasal endoscopic transsphenoidal reoperation results in similar EOR, visual outcome, and improvement in QOL as first-time operations, with no significant increase in complications. EOR is more impacted by tumor volume and prior radiation. Reoperations should be offered to patients with recurrent craniopharyngiomas and may be preferable to radiation in patients in whom GTR or NTR can be achieved.

  View details for DOI 10.3171/2016.1.JNS152238

  View details for Web of Science ID 000393089100010

  View details for PubMedID 27153172

• Endoscopic endonasal approach to the ventral brainstem: anatomical feasibility and surgical limitations. Journal of neurosurgery Essayed, W. I., Singh, H., Lapadula, G., Almodovar-Mercado, G. J., Anand, V. K., Schwartz, T. H. 2017: 1?8

  Abstract

  OBJECTIVE Sporadic cases of endonasal intraaxial brainstem surgery have been reported in the recent literature. The authors endeavored to assess the feasibility and limitations of endonasal endoscopic surgery for approaching lesions in the ventral portion of the brainstem. METHODS Five human cadaveric heads were used to assess the anatomy and to record various measurements. Extended transsphenoidal and transclival approaches were performed. After exposing the brainstem, white matter dissection was attempted through this endoscopic window, and additional key measurements were taken. RESULTS The rostral exposure of the brainstem was limited by the sella. The lateral limits of the exposure were the intracavernous carotid arteries at the level of the sellar floor, the intrapetrous carotid arteries at the level of the petrous apex, and the inferior petrosal sinuses toward the basion. Caudal extension necessitated partial resection of the anterior C-1 arch and the odontoid process. The midline pons and medulla were exposed in all specimens. Trigeminal nerves were barely visible without the use of angled endoscopes. Access to the peritrigeminal safe zone for gaining entry into the brainstem is medially limited by the pyramidal tract, with a mean lateral pyramidal distance (LPD) of 4.8 ± 0.8 mm. The mean interpyramidal distance was 3.6 ± 0.5 mm, and it progressively decreased toward the pontomedullary junction. The corticospinal tracts (CSTs) coursed from deep to superficial in a craniocaudal direction. The small caliber of the medulla with very superficial CSTs left no room for a safe ventral dissection. The mean pontobasilar midline index averaged at 0.44 ± 0.1. CONCLUSIONS Endoscopic endonasal approaches are best suited for pontine intraaxial tumors when they are close to the midline and strictly anterior to the CST, or for exophytic lesions. Approaching the medulla is anatomically feasible, but the superficiality of the eloquent tracts and interposed nerves limit the safe entry zones. Pituitary transposition after sellar opening is necessary to access the mesencephalon.

  View details for PubMedID 28084906

• Microscopic Resection of Recurrent Giant Adenoma and Clip Ligation of Contralateral Internal Carotid Artery Terminus Aneurysm: 3-Dimensional Operative Video. Operative neurosurgery (Hagerstown, Md.) Singh, H., da Silva, H. B., Zeinalizadeh, M., Sekhar, L. N. 2017; 13 (6): 758

  View details for PubMedID 29186610

• A Case of Gigantism. The Art of Neuroendocrinology: A Case-Based Approach to Medical Decision Making. Singh, H., Rote, S., Essayed, W., Schwartz, T. Nova Science Pub Inc.. 2017
• Endoscopic Transsphenoidal Pituitary Surgery: Results and Complications. Transphenoidal Surgery- Complication Avoidance and Management Techniques. Singh, H., Essayed, W., Hussain, I., Yang, K., Anand, V., Schwartz, T. Springer. 2017
• Limitations of the endonasal endoscopic approach in treating olfactory groove meningiomas. A systematic review. Acta neurochirurgica Shetty, S. R., Ruiz-Treviño, A. S., Omay, S. B., Almeida, J. P., Liang, B., Chen, Y. N., Singh, H., Schwartz, T. H. 2017

  Abstract

  To review current management strategies for olfactory groove meningioma (OGM)s and the recent literature comparing endoscopic endonasal (EEA) with traditional transcranial (TCA) approaches.A PubMed search of the recent literature (2011-2016) was performed to examine outcomes following EEA and TCA for OGM. The extent of resection, visual outcome, postoperative complications and recurrence rates were analyzed using percentages and proportions, the Fischer exact test and the Student's t-test using Graphpad PRISM 7.0Aa (San Diego, CA) software.There were 444 patients in the TCA group with a mean diameter of 4.61 (±1.17) cm and 101 patients in the EEA group with a mean diameter of 3.55 (± 0.58) cm (p = 0.0589). GTR was achieved in 90.9% (404/444) in the TCA group and 70.2% (71/101) in the EEA group (p < 0.0001). Of the patients with preoperative visual disturbances, 80.7% (21/26) of patients in the EEA cohort had an improvement in vision compared to 12.83%(29/226) in the TCA group (p < 0.0001). Olfaction was lost in 61% of TCA and in 100% of EEA patients. CSF leaks and meningitis occurred in 25.7% and 4.95% of EEA patients and 6.3% and 1.12% of TCA patients, respectively (p < 0.0001; p = 0.023).Our updated literature review demonstrates that despite more experience with endoscopic resection and skull base reconstruction, the literature still supports TCA over EEA with respect to the extent of resection and complications. EEA may be an option in selected cases where visual improvement is the main goal of surgery and postoperative anosmia is acceptable to the patient or in medium-sized tumors with existing preoperative anosmia. Nevertheless, based on our results, it seems more prudent at this time to use TCA for the majority of OGMs.

  View details for DOI 10.1007/s00701-017-3303-0

  View details for PubMedID 28831590

• Microsurgical Management of Large, Fusiform, Partially Thrombosed Middle Cerebral Artery (M2) Aneurysm with End-to-End M2 Anastomosis: 3-Dimensional Operative Video. Operative neurosurgery (Hagerstown, Md.) Singh, H., da Silva, H. B., Straus, D. C., Zeinalizadeh, M., Sekhar, L. N. 2017; 13 (4): 535

  View details for PubMedID 28838123

• Transpetrosal approach to petro-clival meningioma. Neurosurgical focus Elarjani, T., Shetty, R., Singh, H., da Silva, H. B., Sekhar, L. N. 2017; 43 (VideoSuppl2): V1

  Abstract

  A 38-year-old woman had a 3-week gradual onset of right-sided weakness in the upper and lower extremities. MRI showed a large left petro-clival meningioma encasing the basilar and left superior cerebellar artery and compressing the brainstem. A posterior transpetrosal approach, with a left temporal and retrosigmoid craniotomy and mastoidectomy, was performed. The tumor was removed in a gross-total resection with questionable remnants adherent to the brainstem. Intraoperative partial iatrogenic injury to the left oculomotor nerve was repaired with fibrin glue. Postoperatively, the hemiparesis improved, and the patient was discharged to the rehabilitation center with left oculomotor and abducens palsies. A postoperative MRI scan showed complete resection of tumor with no remnants on the brainstem. A 6-month follow-up examination showed complete resolution of motor symptoms and complete recovery of cranial nerve (CN) palsies affecting CN III and CN VI. The video can be found here: https://youtu.be/vOu6YFA8uoo .

  View details for PubMedID 28967311

• Serum albumin level in spontaneous subarachnoid haemorrhage: More than a mere nutritional marker! British journal of neurosurgery Kapoor, A., Dhandapani, S., Gaudihalli, S., Dhandapani, M., Singh, H., Mukherjee, K. K. 2017: 1

  Abstract

  The role of nutritional markers on outcome following subarachnoid hemorrhage (SAH) has been scarcely described.This is a prospective study of 273 patients with SAH, in which haemoglobin, serum protein and albumin were measured within 24?hours and again at one week following ictus, and analysed with respect to other variables. New neurologic deficits (NND), infarct, mortality and Glasgow outcome scale (GOS) at 3 months were assessed.The values of haemoglobin, total protein and albumin showed significant (p?

  View details for PubMedID 28658989

• Basilar Artery Ectasia Causing Trigeminal Neuralgia: An Evolved Technique of Transpositional Suture-Pexy Oper Neurosurg (Hagerstown) Singh, H., da Silva, H. B., Zeinalizadeh, M., Elarjani, T., Straus, D., Sekhar, L. N. 2017; opx087: 194?99

  Abstract

  Microvascular decompression for patients with trigeminal neuralgia (TGN) is widely accepted as one of the modalities of treatment. The standard approach has been retrosigmoid suboccipital craniotomy with placement of a Teflon pledget to cushion the trigeminal nerve from the offending artery, or cauterize and divide the offending vein(s). However, in cases of severe compression caused by a large artery, the standard decompression technique may not be effective.To describe a unique technique of vasculopexy of the ectatic basilar artery to the tentorium in a patient with TGN attributed to a severely ectatic and tortuous basilar artery. A case series of patients who underwent this technique of vasculopexy for arterial compression is presented.The patient underwent a subtemporal transtentorial approach and the basilar artery was mobilized away from the trigeminal nerve. A suture was then passed through the wall of the basilar artery (tunica media) and secured to the tentorial edge, to keep the artery away from the nerve.The neuralgia was promptly relieved after the operation, with no complications. A postoperative magnetic resonance imaging scan showed the basilar artery to be away from the trigeminal root. In a series of 7 patients who underwent this technique of vasculopexy, no arterial complications were noted at short- or long-term follow-up.Repositioning and vasculopexy of an ectatic basilar artery for the treatment of TGN is safe and effective. This technique can also be used for other neuropathies that result from direct arterial compression.

  View details for DOI 10.1093/ons/opx087

• Endoscopic endonasal versus transcranial approach to tuberculum sellae and planum sphenoidale meningiomas in a similar cohort of patients. Journal of neurosurgery Bander, E. D., Singh, H., Ogilvie, C. B., Cusic, R. C., Pisapia, D. J., Tsiouris, A. J., Anand, V. K., Schwartz, T. H. 2017: 1?9

  Abstract

  OBJECTIVE Planum sphenoidale (PS) and tuberculum sellae (TS) meningiomas cause visual symptoms due to compression of the optic chiasm. The treatment of choice is surgical removal with the goal of improving vision and achieving complete tumor removal. Two options exist to remove these tumors: the transcranial approach (TCA) and the endonasal endoscopic approach (EEA). Significant controversy exists regarding which approach provides the best results and whether there is a subset of patients for whom an EEA may be more suitable. Comparisons using a similar cohort of patients, namely, those suitable for gross-total resection with EEA, are lacking from the literature. METHODS The authors reviewed all cases of PS and TS meningiomas that were surgically removed at Weill Cornell Medical College between 2000 and 2015 (TCA) and 2008 and 2015 (EEA). All cases were shown to a panel of 3 neurosurgeons to find only those tumors that could be removed equally well either through an EEA or TCA to standardize both groups. Volumetric measurements of preoperative and postoperative tumor size, FLAIR images, and apparent diffusion coefficient maps were assessed by 2 independent reviewers and compared to assess extent of resection and trauma to the surrounding brain. Visual outcome and complications were also compared. RESULTS Thirty-two patients were identified who underwent either EEA (n = 17) or TCA (n = 15). The preoperative tumor size was comparable (mean 5.58 ± 3.42 vs 5.04 ± 3.38 cm(3) [± SD], p = 0.661). The average extent of resection achieved was not significantly different between the 2 groups (98.80% ± 3.32% vs 95.13% ± 11.69%, p = 0.206). Postoperatively, the TCA group demonstrated a significant increase in the FLAIR/edema signal compared with EEA patients (4.15 ± 7.10 vs -0.69 ± 2.73 cm(3), p = 0.014). In addition, the postoperative diffusion-weighted imaging signal of cytotoxic ischemic damage was significantly higher in the TCA group than in the EEA group (1.88 ± 1.96 vs 0.40 ± 0.55 cm(3), p =0.008). Overall, significantly more EEA patients experienced improved or stable visual outcomes compared with TCA patients (93% vs 56%, p = 0.049). Visual deterioration was greater after TCA than EEA (44% vs 0%, p = 0.012). While more patients experienced postoperative seizures after TCA than after EEA (27% vs 0%, p = 0.038), there was a trend toward more CSF leakage and anosmia after EEA than after TCA (11.8% vs 0%, p = 0.486 and 11.8% vs 0%, p = 0.118, respectively). CONCLUSIONS In this small single-institution study of similarly sized and located PS and TS meningiomas, EEA provided equivalent rates of resection with better visual results, less trauma to the brain, and fewer seizures. These preliminary results merit further investigation in a larger multiinstitutional study and may support EEA resection by experienced surgeons in a subset of carefully selected PS and TS meningiomas.

  View details for PubMedID 28128693

• Brain Stem Cavernous Malformations: Operative Nuances of a Less-Invasive Resection Technique. Operative neurosurgery (Hagerstown, Md.) Singh, H., Elarjani, T., da Silva, H. B., Shetty, R., Kim, L., Sekhar, L. N. 2017

  Abstract

  Different operative techniques are reported for the resection of brainstem cavernous malformations (BSCMs). The senior author has previously reported on a less-invasive technique of entering the brain stem with piecemeal removal of BSCMs, especially the deep-seated ones.To present a larger series of these lesions, emphasizing the approach to the brain stem via case selection. We discuss the nuances of the less-invasive operative technique through case illustrations and intraoperative videos.A retrospective review of 46 consecutive cases of BSCMs, with their clinical and radiographic data, was performed. Nine cases were selected to illustrate 7 different operative approaches, and discuss surgical nuances of the less-invasive technique unique to each.Postoperative morbidity, defined as an increase in modified Rankin Scale, was observed in 5 patients (10.9%). A residual BSCM was present in 2 patients (4.3%); both underwent reoperation to remove the remainder. At follow-up of 31.1 ± 27.8 mo, 3 patients experienced recurrence (6.5%). Overall, 65% of our patients improved, 20% stayed the same, and 11% worsened postsurgery. Two patients died, yielding a mortality of 4.3%.Using the less-invasive resection technique for piecemeal BSCM removal, in appropriately selected patients, has yielded comparable to improved patient outcomes over existing large series. In our experience, lateral, anterolateral, and posterolateral approaches are favorable over direct midline (dorsal or ventral) approaches. A thorough understanding of brain-stem safe-entry zones, in conjunction with appropriate approach selection, is key to a good outcome in challenging cases.

  View details for PubMedID 29228395

• Endoscopic endonasal odontoid resection with real-time intraoperative image-guided computed tomography: report of 4 cases. Journal of neurosurgery Singh, H., Rote, S., Jada, A., Bander, E. D., Almodovar-Mercado, G. J., Essayed, W. I., Härtl, R., Anand, V. K., Schwartz, T. H., Greenfield, J. P. 2017: 1?6

  Abstract

  The authors present 4 cases in which they used intraoperative CT (iCT) scanning to provide real-time image guidance during endonasal odontoid resection. While intraoperative CT has previously been used as a confirmatory test after resection, to the authors' knowledge this is the first time it has been used to provide real-time image guidance during endonasal odontoid resection. The operating room setup, as well as the advantages and pitfalls of this approach, are discussed. A mobile intraoperative CT scanner was used in conjunction with real-time craniospinal neuronavigation in 4 patients who underwent endoscopic endonasal odontoidectomy for basilar invagination. All patients underwent a successful decompression. In 3 of the 4 patients, real-time intraoperative CT image guidance was instrumental in achieving a comprehensive decompression. In 3 (75%) cases in which the right nostril was the predominant working channel, there was a tendency for asymmetrical decompression toward the right side, meaning that residual bone was seen on the left, which was subsequently removed prior to completion of the surgery. Endoscopic endonasal odontoid resection with real-time intraoperative image-guided CT scanning is feasible and provides accurate intraoperative localization of pathology, thereby increasing the chance of a complete odontoidectomy. For right-handed surgeons operating predominantly through the right nostril, special attention should be paid to the contralateral side of the resection, where there is often a tendency for residual pathology.

  View details for PubMedID 28621629

• Cavernous Sinus Invasion in Pituitary Adenomas: Systematic Review and Pooled Data Meta-Analysis of Radiologic Criteria and Comparison of Endoscopic and Microscopic Surgery WORLD NEUROSURGERY Dhandapani, S., Singh, H., Negm, H. M., Cohen, S., Anand, V. K., Schwartz, T. H. 2016; 96: 36-46

  Abstract

  Despite the substantial impact of cavernous sinus invasion(CSI) in pituitary adenoma surgery, its radiological determination has been inconsistent and variable, with unclear role of endonasal endoscopic surgery. This is a systematic review and pooled data meta-analysis of literature to ascertain the best radiological criteria for CSI, and verify the efficacy and safety of endonasal endoscopic approach.We searched MEDLINE database(1993-2015) to identify studies on radiological criteria for CSI, and endonasal surgery. Using PRISMA guidelines, the included studies were reviewed for CSI criteria, gross total resection(GTR), endocrine remission(ER), cranial nerve(CN) deficits, carotid injury and other complications.The prevalence of CSI was 43% radiographically as compared with 18% intra-operatively(p<0.001). The radiological criteria of inferolateral venous compartment obliteration(ILVCO) and Knosp 3-4 had highest correlation with intra-operative CSI and lowest correlation with gross total resection(GTR). Microscopy had significantly overestimated intra-operative CSI compared with endoscopy(p<0.001) for each Knosp grade. Endoscopy had significantly higher GTR than microscopy particularly for Knosp 3-4(47% versus 21%;p=0.001). Carotid injury and cranial nerve deficits occurred in 0.9% and 5% respectively with endoscopy. Among endoscopic series with CSI, GTR% demonstrated significant correlation with number of patients in the series(p<0.01), but no correlation with complications, indicating the relative safety of endonasal endoscopy in experienced hands for removing tumors with CSI.Knosp 3-4 remains the best objective indicator of CSI. Microscopy tends to overestimate intra-operative CSI compared to endoscopy. Among pituitary adenomas with CSI, GTR in endoscopic series is higher than microscopy, and improves with experience without significant additional morbidity.

  View details for DOI 10.1016/j.wneu.2016.08.088

  View details for Web of Science ID 000396442500007

  View details for PubMedID 27591098

• Resection of pituitary tumors: endoscopic versus microscopic. Journal of neuro-oncology Singh, H., Essayed, W. I., Cohen-Gadol, A., Zada, G., Schwartz, T. H. 2016; 130 (2): 309-317

  Abstract

  Transsphenoidal microscopic pituitary surgery has long been considered the gold standard in surgical treatment of pituitary tumors. Endonasal endoscopic pituitary surgery has come into prominence over the last two decades as an alternative to microscopic surgery. In this review, we use recent literature to discuss the advantages and disadvantages of each approach. Our review shows that for small intrasellar tumors, both approaches appear equally effective in experienced hands. For larger tumors with extrasellar extension, the endoscopic approach offers several advantages and may improve outcomes associated with the extent of resection and postoperative complications.

  View details for PubMedID 27161249

• Required Reading: The Most Impactful Articles in Endoscopic Endonasal Skull Base Surgery. World neurosurgery Zhang, M., Singh, H., Almodovar-Mercado, G. J., Anand, V. K., Schwartz, T. H. 2016; 92: 499-512 e2

  Abstract

  Endoscopic endonasal skull base surgery has become a widely accepted field in neurosurgery and otolaryngology over the last 15 years. However, there has yet to be a formal curation of the most impactful articles for an introductory curriculum to its technical evolution.The Science Citation Index Expanded was used to generate a citation rank list (October 2015) on articles relevant to endoscopic skull base surgery. The top 35 cited articles overall, as well as the top 15 since 2009, were identified. Journal, year, author, study population, article format, and level of evidence were compiled. Additional surgeon-experts were polled and made recommendations for significant contributions to the literature.The top 35 publications ranged from 98 to 467 citations and were published in 10 different journals. Four articles had over 250 citations. A period of frequent contribution occurred between 2005-2009, when 21/35 reports were published. 18/35 articles were case series, and 13/35 were technical reports. There were 11/35 articles focused primarily on pituitary surgery, and 10/35 on extra-sellar lesions. The top 15 articles since 2009 had 8/15 articles focus on extra-sellar lesions. Polled surgeons consistently identified the most prominently cited articles, and their recommendations drew attention to CSF-leak as well as extra-sellar management.Identification of the most cited works within endoscopic endonasal skull base surgery demonstrates greater anatomical access and safety over the last two decades. These articles can serve as an educational tool for novices or mid-level practitioners wishing to obtain a greater understanding of the field.

  View details for DOI 10.1016/j.wneu.2016.06.016

  View details for PubMedID 27312387

• Impact of Early Leukocytosis and Elevated High-Sensitivity C-Reactive Protein on Delayed Cerebral Ischemia and Neurologic Outcome After Subarachnoid Hemorrhage. World neurosurgery Srinivasan, A., Aggarwal, A., Gaudihalli, S., Mohanty, M., Dhandapani, M., Singh, H., Mukherjee, K. K., Dhandapani, S. 2016; 90: 91-95

  Abstract

  The role of inflammatory response in the pathophysiology of SAH is being increasingly recognized. This is a study to analyze the impact of cellular and biochemical markers of early inflammatory response to ictus on outcome following SAH.SAH patients were prospectively studied for markers of early cellular, biochemical, and cytotoxic inflammatory response such as total leucocyte count (TLC), high sensitive C-reactive protein (hs-CRP), and lactate dehydrogenase (LDH). The relationship of these markers on delayed cerebral ischemia (DCI), new infarct and Glasgow Outcome Scale (GOS) at 3 months was studied.A total of 246 patients were studied. Of these, 94 patients who developed DCI had significantly higher TLC (11.2 [+4.0] vs 9.4 [2.9]10(3)/mm(3), p=0.001) while 62 patients with new infarct had significantly higher TLC (11.0 [+3.6] vs 9.8 [+3.4]10(3)/mm(3), p=0.05).GOS had a significant inverse relationship to admission TLC. The mean TLC [+SD] was 12.7 [+4.2], 11.7 [+3.1], 10.2 [+3.4] & 9.3 [+2.8] among patients with GOS 1, 3, 4 & 5 respectively (p<0.001). hs-CRP showed trend of an inverse relationship to GOS in univariate analysis, while LDH had no relationship with any outcome parameter. In multivariate analysis, higher admission TLC had significant association with DCI (p=0.01) and poorer GOS (p<0.001), and higher hs-CRP had significant association with poorer GOS (p=0.05).Leukocytosis response to ictus seems to have significant independent association with both DCI and poor GOS, and hs-CRP levels had significant independent association with poor GOS, indicating preeminence of early cellular response in SAH pathophysiology.

  View details for DOI 10.1016/j.wneu.2016.02.049

  View details for PubMedID 26898490

• Nonrandom spatial clustering of spontaneous anterior fossa cerebrospinal fluid fistulas and predilection for the posterior cribriform plate. Journal of neurosurgery Murray, R. D., Friedlander, R., Hanz, S., Singh, H., Anand, V. K., Schwartz, T. H. 2016: 1?5

  Abstract

  OBJECTIVE The anterior skull base is a common site for the spontaneous development of meningoceles, encephaloceles, and meningoencephaloceles that can lead to cerebrospinal fluid (CSF) fistula formation, particularly in association with idiopathic intracranial hypertension. In some circumstances the lesions are difficult to localize. Whether all sites in the anterior skull base are equally prone to fistula formation or whether they are distributed randomly throughout the anterior skull base is unknown, although the anterior cribriform plate has been proposed as the most frequent location. The purpose of this study was to identify sites of predilection in order to provide assistance for clinicians in finding occult leaks and increase the understanding of the etiology of this pathology. METHODS The authors performed a retrospective review of a prospectively acquired surgical database of all endonasal endoscopic surgeries performed at Weill Cornell Medical College by the senior authors. Spontaneous CSF fistulas of the anterior skull base were identified. The anatomical sites of the defects were located on radiographic images and normalized to a theoretical 4 × 2 grid representing the anterior midline skull base. Data from the left and right skull base were combined to increase statistical power. This grid was then used to analyze the distribution of defects. Frequency analysis was performed by means of a chi-square test, with a subsequent Monte Carlo simulation to further strengthen the statistical support of the conclusions. RESULTS Nineteen cases of spontaneous CSF fistulas were identified. Frequency analysis using chi-square indicated a nonrandom distribution of sites (p = 0.035). Monte Carlo simulation supported this conclusion (p = 0.034). Seventy-four percent of cases occurred in the cribriform plate (p = 0.086). Moreover, 37% of all defects occurred in the posterior third of the cribriform plate. CONCLUSIONS Anterior skull base spontaneous CSF leaks are distributed in a nonrandom fashion. The most likely site of origin of the spontaneous CSF leaks of the anterior midline skull base is the cribriform plate, particularly the posterior third of the plate, likely because of the lack of significant thick bony buttressing. Clinicians searching for occult spontaneous leaks of the anterior skull base should examine the cribriform plate, especially the posterior third with particularly close scrutiny.

  View details for DOI 10.3171/2016.4.JNS152975

  View details for PubMedID 27367237

• Pediatric Endonasal Endoscopic Skull Base Surgery: A Case Based Manual. Singh, H., Greenfield, J., Anand, V., Schwartz, T. Endo-Press, Tuttlingen, Germany.. 2016
• Fundamentals of Spine Surgery. Spine Surgery: Techniques, Complication Avoidance, and Management Singh, H., Ghobrial, G., Haan, S., Harrop, J. Saunders. 2016; 4th Ed.
• Scoliotic Cervical Deformity. Spine Surgery: Techniques, Complication Avoidance, and Management Singh, H., Ghobrial, G., Harrop, J. Saunders. 2016; 4th Ed.
• Intraoperative Neurophysiological Monitoring for Endoscopic Endonasal Approaches to the Skull Base: A Technical Guide. Scientifica Singh, H., Vogel, R. W., Lober, R. M., Doan, A. T., Matsumoto, C. I., Kenning, T. J., Evans, J. J. 2016; 2016: 1751245-?

  Abstract

  Intraoperative neurophysiological monitoring during endoscopic, endonasal approaches to the skull base is both feasible and safe. Numerous reports have recently emerged from the literature evaluating the efficacy of different neuromonitoring tests during endonasal procedures, making them relatively well-studied. The authors report on a comprehensive, multimodality approach to monitoring the functional integrity of at risk nervous system structures, including the cerebral cortex, brainstem, cranial nerves, corticospinal tract, corticobulbar tract, and the thalamocortical somatosensory system during endonasal surgery of the skull base. The modalities employed include electroencephalography, somatosensory evoked potentials, free-running and electrically triggered electromyography, transcranial electric motor evoked potentials, and auditory evoked potentials. Methodological considerations as well as benefits and limitations are discussed. The authors argue that, while individual modalities have their limitations, multimodality neuromonitoring provides a real-time, comprehensive assessment of nervous system function and allows for safer, more aggressive management of skull base tumors via the endonasal route.

  View details for DOI 10.1155/2016/1751245

  View details for PubMedID 27293965

• Minimally Invasive Lumbar Pedicle Screw Fixation Using Cortical Bone Trajectory - A Prospective Cohort Study on Postoperative Pain Outcomes. Cure¯us Chen, Y., Deb, S., Pham, L., Singh, H. 2016; 8 (7)

  Abstract

  Our study aims to evaluate the clinical outcomes of cortical screws in regards to postoperative pain.Pedicle screw fixation is the current mainstay technique for posterior spinal fusion. Over the past decade, a new technique called cortical screw fixation has been developed, which allows for medialized screw placement through stronger cortical bone. There have been several studies that showed either biomechanical equivalence or superiority of cortical screws. However, there is currently only a single study in the literature looking at clinical outcomes of cortical screw fixation in patients who have had no prior spine surgery.We prospectively looked at the senior author's patients who underwent cortical versus pedicle lumbar screw fixation surgeries between 2013 and 2015 for lumbar degenerative disease. Eighteen patients underwent cortical screw fixation, and 15 patients underwent traditional pedicle screw fixation. We looked at immediate postoperative pain, changes in short-term pain (six to 12 weeks post-surgery), and changes in long-term pain (six to eight months). All pain outcomes were measured using a visual analog scale ranging from 1 to 10. Mann-Whitney or Kruskal-Wallis tests were used to measure continuous data, and the Fisher Exact test was used to measure categorical data as appropriate.Our results showed that the cortical screw cohort showed a trend towards having less peak postoperative pain (p = 0.09). The average postoperative pain was similar between the two cohorts (p = 0.93). There was also no difference in pain six to 12 weeks after surgery (p = 0.8). However, at six to eight months, the cortical screw cohort had worse pain compared to the pedicle screw cohort (p = 0.02).The cortical screw patients showed a trend towards less peak pain in the short-term (one to three days post-surgery) and more pain in the long-term (six to eight months post-surgery) compared to pedicle screw patients. Both cohorts had a statistically significant reduction in pain levels compared to preoperative pain. More studies are needed to further evaluate postoperative pain, long-term functional outcomes, and fusion rates in patients who undergo cortical screw fixation.

  View details for DOI 10.7759/cureus.714

  View details for PubMedID 27610286

  View details for PubMedCentralID PMC5001953

• Reoperative endoscopic endonasal surgery for residual or recurrent pituitary adenomas. Journal of neurosurgery Negm, H. M., Al-Mahfoudh, R., Pai, M., Singh, H., Cohen, S., Dhandapani, S., Anand, V. K., Schwartz, T. H. 2016: 1?12

  Abstract

  OBJECTIVE Regrowth of the lesion after surgical removal of pituitary adenomas is uncommon unless subtotal resection was originally achieved in the first surgery. Treatment for recurrent tumor can involve surgery or radiotherapy. Locations of residual tumor may vary based on the original approach. The authors evaluated the specific sites of residual or recurrent tumor after different transsphenoidal approaches and describe the surgical outcome of endoscopic endonasal transsphenoidal reoperation. METHODS The authors analyzed a prospectively collected database of a consecutive series of patients who had undergone endoscopic endonasal surgeries for residual or recurrent pituitary adenomas after an original transsphenoidal microscopic or endoscopic surgery. The site of the recurrent tumor and outcome after reoperation were noted and correlated with the primary surgical approach. The chi-square or Fisher exact test was used to compare categorical variables, and the Mann-Whitney U-test was used to compare continuous variables between surgical groups. RESULTS Forty-one patients underwent surgery for residual/recurrent pituitary adenoma from 2004 to 2015 at Weill Cornell Medical College. The previous treatment was a transsphenoidal microscopic (n = 22) and endoscopic endonasal (n = 19) surgery. In 83.3% patients (n = 30/36) there was postoperative residual tumor after the initial surgery. A residual tumor following endonasal endoscopic surgery was less common in the sphenoid sinus (10.5%; 2/19) than it was after microscopic transsphenoidal surgery (72.7%; n =16/22; p = 0.004). Gross-total resection (GTR) was achieved in 58.5%, and either GTR or near-total resection was achieved in 92.7%. Across all cases, the average extent of resection was 93.7%. The rate of GTR was lower in patients with Knosp-Steiner Grade 3-4 invasion (p < 0.0005). Postoperative CSF leak was seen in only one case (2.4%), which stopped with lumbar drainage. Visual fields improved in 52.9% (n = 9/17) of patients and were stable in 47% (n = 8/17). Endocrine remission was achieved in 77.8% (n = 14/18) of cases, 12 by surgery alone and 2 by adjuvant medical (n = 1) and radiation (n = 1) therapy. New diabetes insipidus occurred in 4.9% (n = 2/41) of patients-in one of whom an additional single anterior hormonal axis was compromised-and 9.7% (n = 4/41) of patients had a new anterior pituitary hormonal insufficiency. CONCLUSIONS Endonasal endoscopic reoperation is extremely effective at removing recurrent or residual pituitary adenomas that remain after a prior surgery, and it may be preferable to radiation therapy particularly in symptomatic patients. Achievement of GTR is less common when lateral cavernous sinus invasion is present. The locations of residual/recurrent tumor were more likely sphenoidal and parasellar following a prior microscopic transsphenoidal surgery and sellar following a prior endonasal endoscopic surgery.

  View details for PubMedID 27791524

• Endonasal Access to the Upper Cervical Spine: Part 2-Cadaveric Analysis. Journal of neurological surgery. Part B, Skull base Singh, H., Lober, R. M., Virdi, G. S., Lopez, H., Rosen, M., Evans, J. 2015; 76 (4): 262-265

  Abstract

  Objectives?The study aims to determine factors that augment endonasal exposure of the cervical spine. Setting?We used fluoroscopy and endoscopy to study endonasal visualization of the upper cervical spine. Participants?Ten cadavers with normal anatomy were studied. Main Outcome Measures?Endoscopic visualization was simulated with projected lines from an endoscope to the cervical spine in multiple positions. Results?Neck position alone did not affect the extent of endonasal exposure of the upper cervical spine, although there was a trend correlating the extended neck position with more caudal exposure. The greatest impact was with concurrent use of a 30-degree endoscope and neck extension, and more caudal access was achieved by tilting the endoscope against the piriform aperture, using the posterior tip of the hard palate as the fulcrum. Conclusions?Concurrent use of a 30-degree endoscope and neck extension increased the degree of exposure down the cervical spine. Maximum endonasal exposure of the upper cervical spine was obtained by maneuvering instruments at the fulcrum of the posterior hard palate and the nares, rather than changing the position of the neck alone. These results complement radiographic morphometric data in Part 1 of this study for preoperative assessment and surgical planning.

  View details for DOI 10.1055/s-0034-1395490

  View details for PubMedID 26225313

  View details for PubMedCentralID PMC4516725

• Endoscopic approaches to the cervical spine: analyzing the state of the evidence Minerva Ortopedica e Traumatologica Singh, H., Moraff, A., Evans, J. 2015; 66 (1): 63-70
• Cervical Open Reduction Techniques - Anterior and Posterior Approach. Handbook of Spine Surgery Singh, H., Ghobrial, G., Harrop, J. Thieme. 2015; 2nd Ed.
• History of simulation in medicine: from resusci annie to the ann myers medical center. Neurosurgery Singh, H., Kalani, M., Acosta-Torres, S., El Ahmadieh, T. Y., Loya, J., Ganju, A. 2013; 73: S9-S14

  Abstract

  Medical and surgical graduate medical education has historically used a halstedian approach of "see one, do one, teach one." Increased public demand for safety, quality, and accountability in the setting of regulated resident work hours and limited resources is driving the development of innovative educational tools. The use of simulation in nonmedical, medical, and neurosurgical disciplines is reviewed in this article. Simulation has been validated as an educational tool in nonmedical fields such as aviation and the military. Across most medical and surgical subspecialties, simulation is recognized as a valuable tool that will shape the next era of medical education, postgraduate training, and maintenance of certification.

  View details for DOI 10.1227/NEU.0000000000000093

  View details for PubMedID 24051890

• Endonasal Access to the Upper Cervical Spine, Part One: Radiographic Morphometric Analysis JOURNAL OF NEUROLOGICAL SURGERY PART B-SKULL BASE Singh, H., Grobelny, B. T., Harrop, J., Rosen, M., Lober, R. M., Evans, J. 2013; 74 (3): 176-184

  View details for DOI 10.1055/s-0033-1342923

  View details for Web of Science ID 000321272900012

• Brain tuberculoma in a non-endemic area. Infectious disease reports Lober, R. M., Veeravagu, A., Singh, H. 2013; 5 (1)

  Abstract

  Brain tuberculoma has previously accounted for up to a third of new intracranial lesions in areas endemic with tuberculosis, but is unexpected in the United States and other Western countries with improved disease control. Here we show the importance of considering this diagnosis in at-risk patients, even with no definitive pulmonary involvement. We describe a young man who presented with partial seizures and underwent craniotomy for resection of a frontoparietal tuberculoma. He subsequently completed six months of antituberculosis therapy and was doing well without neurological sequelae or evidence of recurrence five months after completion of therapy. With resurgence of tuberculosis cases in the United States and other Western countries, intracerebral tuberculoma should remain a diagnostic consideration in at-risk patients with new space occupying lesions. Mass lesions causing neurological sequelae can be safely addressed surgically and followed with antituberculosis therapy.

  View details for DOI 10.4081/idr.2013.e1

  View details for PubMedID 24470952

• Traumatic epistaxis: Skull base defects, intracranial complications and neurosurgical considerations. International journal of surgery case reports Veeravagu, A., Joseph, R., Jiang, B., Lober, R. M., Ludwig, C., Torres, R., Singh, H. 2013; 4 (8): 656-661

  Abstract

  Endonasal procedures may be necessary during management of craniofacial trauma. When a skull base fracture is present, these procedures carry a high risk of violating the cranial vault and causing brain injury or central nervous system infection.A 52-year-old bicyclist was hit by an automobile at high speed. He sustained extensive maxillofacial fractures, including frontal and sphenoid sinus fractures (Fig. 1). He presented to the emergency room with brisk nasopharyngeal hemorrhage, and was intubated for airway protection. He underwent emergent stabilization of his nasal epistaxis by placement of a Foley catheter in his left nare and tamponade with the Foley balloon. A six-vessel angiogram showed no evidence of arterial dissection or laceration. Imaging revealed inadvertent insertion of the Foley catheter and deployment of the balloon in the frontal lobe (Fig. 2). The balloon was subsequently deflated and the Foley catheter removed. The patient underwent bifrontal craniotomy for dural repair of CSF leak. He also had placement of a ventriculoperitoneal shunt for development of post-traumatic hydrocephalus. Although the hospital course was a prolonged one, he did make a good neurological recovery.The authors review the literature involving violation of the intracranial compartment with medical devices in the settings of craniofacial trauma.Caution should be exercised while performing any endonasal procedure in the settings of trauma where disruption of the anterior cranial base is possible.

  View details for DOI 10.1016/j.ijscr.2013.04.033

  View details for PubMedID 23792475

  View details for PubMedCentralID PMC3710897

• Extradural Spinal Meningiomas. Tumors of the central nervous system. Vol 10 Hanna, A., Nguyen, P., Singh, H., Harrop, J. Springer. 2013
• Primary spinal germ cell tumors: a case analysis and review of treatment paradigms. Case reports in medicine Loya, J. J., Jung, H., Temmins, C., Cho, N., Singh, H. 2013; 2013: 798358-?

  Abstract

  Objective. Primary intramedullary spinal germ cell tumors are exceedingly rare. As such, there are no established treatment paradigms. We describe our management for spinal germ cell tumors and a review of the literature. Clinical Presentation. We describe the case of a 45-year-old man with progressive lower extremity weakness and sensory deficits. He was found to have enhancing intramedullary mass lesions in the thoracic spinal cord, and pathology was consistent with an intramedullary germ cell tumor. A video presentation of the case and surgical approach is provided. Conclusion. As spinal cord germinomas are highly sensitive to radiation and chemotherapy, a patient can be spared radical surgery. Diverse treatment approaches exist across institutions. We advocate biopsy followed by local radiation, with or without adjuvant chemotherapy, as the optimal treatment for these tumors. Histological findings have prognostic value if syncytiotrophoblastic giant cells (STGCs) are found, which are associated with a higher rate of recurrence. The recurrence rate in STGC-positive spinal germinomas is 33% (2/6), whereas it is only 8% in STGC-negative tumors (2/24). We advocate limited volume radiotherapy combined with systemic chemotherapy in patients with high risk of recurrence. To reduce endocrine and neurocognitive side effects, cranio-spinal radiation should be used as a last resort in patients with recurrence.

  View details for DOI 10.1155/2013/798358

  View details for PubMedID 24312128

  View details for PubMedCentralID PMC3838823

• Anterior Odontoid Resection: The Transoral Approach. Operative Techniques: Spine Surgery Ghobrial, G., Baron, E., Choi, D., Singh, H., Harrop, J., Vaccaro, A., Crockard, A. Saunders. 2012; 2nd Ed.
• Fundamentals of Spine Surgery. Spine Surgery: Techniques, Complication Avoidance, and Management Singh, H., Harrop, J. Saunders. 2012; 3rd Ed.
• Scoliotic Cervical Deformity. Spine Surgery: Techniques, Complication Avoidance, and Management Singh, H., Ghobrial, G., Harrop, J. Saunders. 2012; 3rd Ed.
• Timing of decompression surgery for traumatic spinal cord injury in a patient with an incomplete myelopathy. Spine Surgery: Techniques, Complication Avoidance, and Management Teufack, S., Singh, H., Harrop, J. Saunders. 2012; 3rd Ed.
• Thoracolumbar spine fractures: State of the Evidence. The Evidence for Neurosurgery Ghobrial, G., Singh, H., Harrop, J. Tfm Publishing Limited. 2012; 1st Ed.
• High-resolution ultrasonography in the diagnosis and intraoperative management of peripheral nerve lesions Clinical article JOURNAL OF NEUROSURGERY Lee, F. C., Singh, H., Nazarian, L. N., Ratliff, J. K. 2011; 114 (1): 206-211

  Abstract

  The diagnosis of peripheral nerve lesions relies on clinical history, physical examination, electrodiagnostic studies, and radiography. Magnetic resonance neurography offers high-resolution visualization of structural peripheral nerve lesions. The availability of MR neurography may be limited, and the costs can be significant. By comparison, ultrasonography is a portable, dynamic, and economic technology. The authors explored the clinical applicability of high-resolution ultrasonography in the preoperative and intraoperative management of peripheral nerve lesions.The authors completed a retrospective analysis of 13 patients undergoing ultrasonographic evaluation and surgical treatment of nerve lesions at their institution (nerve entrapment [5], trauma [6], and tumor [2]). Ultrasonography was used for diagnostic (12 of 13 cases) and intraoperative management (6 of 13 cases). The authors examine the initial impact of ultrasonography on clinical management.Ultrasonography was an effective imaging modality that augmented electrophysiological and other neuroimaging studies. The modality provided immediate visualization of a sutured peroneal nerve after a basal cell excision, prompting urgent surgical exploration. Ultrasonography was used intraoperatively in 2 cases to identify postoperative neuromas after mastectomy, facilitating focused excision. Ultrasonography correctly diagnosed an inflamed lymph node in a patient in whom MR imaging studies had detected a schwannoma, and the modality correctly diagnosed a tendinopathy in another patient referred for ulnar neuropathy. Ultrasonography was used in 6 patients to guide the surgical approach and to aid in intraoperative localization; it was invaluable in localizing the proximal segment of a radial nerve sectioned by a humerus fracture. In all cases, ultrasonography demonstrated the correct lesion diagnosis and location (100%); in 7 (58%) of 12 cases, ultrasonography provided the correct diagnosis when other imaging and electrophysiological studies were inconclusive or inadequate.High-resolution ultrasonography may provide an economical and accurate imaging modality with utility in diagnosis and management of peripheral nerve lesions. Further research is required to assess the role of ultrasonography in evaluation of peripheral nerve pathology.

  View details for DOI 10.3171/2010.2.JNS091324

  View details for Web of Science ID 000285669500041

  View details for PubMedID 20225925

• Cervical Open Reduction Techniques - Anterior and Posterior Approach. Handbook of Spine Surgery Singh, H., Ghobrial, G., Harrop, J. Thieme. 2011; 1st Ed.
• Dorsal Epidural Intervertebral Disk Herniation With Atypical Radiographic Findings: Case Report and Literature Review JOURNAL OF SPINAL CORD MEDICINE Teufack, S. G., Singh, H., Harrop, J., Ratliff, J. 2010; 33 (3): 268-271

  Abstract

  Intervertebral disk herniation is relatively common. Migration usually occurs in the ventral epidural space; rarely, disks migrate to the dorsal epidural space due to the natural anatomical barriers of the thecal sac.Case report.A 49-year-old man presented with 1 week of severe back pain with bilateral radiculopathy to the lateral aspect of his lower extremities and weakness of the ankle dorsiflexors and toe extensors. Lumbar spine magnetic resonance imaging with gadolinium revealed a peripheral enhancing dorsal epidural lesion with severe compression of the thecal sac. Initial differential diagnosis included spontaneous hematoma, synovial cyst, and epidural abscess. Posterior lumbar decompression was performed; intraoperatively, the lesion was identified as a large herniated disk fragment.Dorsal migration of a herniated intervertebral disk is rare and may be difficult to definitively diagnose preoperatively. Dorsal disk migration may present in a variety of clinical scenarios and, as in this case, may mimic other epidural lesions on magnetic resonance imaging.

  View details for Web of Science ID 000281007700011

  View details for PubMedID 20737802

• Ventral surgical approaches to craniovertebral junction chordomas. Neurosurgery Singh, H., Harrop, J., Schiffmacher, P., Rosen, M., Evans, J. 2010; 66 (3): 96-103

  Abstract

  Chordomas are primarily malignant tumors encountered at either end of the neural axis; the craniovertebral junction and the sacrococcygeal junction. In this article, we discuss the surgical management of craniovertebral junction chordomas.In this paper, we discuss the surgical management of craniovertebral junction chordomas.The following approaches are illustrated: transoral-transpalatopharyngeal approach, high anterior cervical retropharyngeal approach, endoscopic transoral approach, and endoscopic transnasal approach. No single operative approach can be used for all craniovertebral chordomas. Therefore, the location of the tumor dictates which approach or approaches should be used.

  View details for DOI 10.1227/01.NEU.0000365855.12257.D1

  View details for PubMedID 20173533

• Ventral Surgical Approaches to Craniovertebral Junction Chordomas. Neurosurgery Singh, H., Harrop, J., Schiffmacher, P., Rosen, M., Evans, J. 2010; 66 (suppl_3): A96?A103

  View details for DOI 10.1227/01.NEU.0000365855.12257.D1

  View details for PubMedID 28180882

• Curvularia fungi presenting as a large cranial base meningioma: case report. Neurosurgery Singh, H., Irwin, S., Falowski, S., Rosen, M., Kenyon, L., Jungkind, D., Evans, J. 2008; 63 (1): E177-?

  Abstract

  Fungal infections are emerging as a growing threat to human health, especially in immunocompromised patients. Candida, Cryptococcus, and Aspergillus are a few of the commonly encountered organisms leading to brain abscesses. In this report, we describe Curvularia geniculata as the causative agent in central nervous system infection.Our review of the literature did not reveal a similar published case of central nervous system infection with this organism. A 35-year-old African-American man presented with obstructive hydrocephalus from a large cranial base lesion. Imaging characteristics on computed tomographic and magnetic resonance imaging scans were consistent with those of a cranial base meningioma.The patient underwent an endoscopic transnasal/transclival approach to the anterior middle cranial base for biopsy and decompression of this lesion. A spindle cell proliferation was observed on frozen section, which favored a diagnosis of meningioma. However, on permanent sections, we identified fungal hyphae with budding. Subsequent biopsies grew Curvularia in fungal cultures. Deoxyribonucleic acid sequencing was used to confirm the identification of the isolate as Curvularia geniculata.Limited data are available for in vitro susceptibility testing of Curvularia, and treatment modalities have not yet been standardized. The prognosis is usually poor. Despite being treated with voriconazole and intravenous amphotericin, this patient progressed to multiorgan failure and ultimately died. This is the first reported case of central nervous system infection by Curvularia geniculata.

  View details for DOI 10.1227/01.NEU.0000335086.77846.0A

  View details for PubMedID 18728558