Dr. DeSouza is an Instructor in the Department of Neurology and Neurological Sciences. She completed her PhD at the University of Toronto where her research focused on MRI to examine brain abnormalities and treatment-related plasticity in individuals with the chronic facial pain disorder, trigeminal neuralgia.

With her mentor, Dr. Robert Cowan, Dr. DeSouza is currently investigating the basic mechanisms and biomarkers associated with chronic daily headache subtypes using multimodal neuroimaging. In addition, she is a member of the Brain Stimulation Lab (BSL) in the Department of Psychiatry and Behavioral Sciences. With the Director of the BSL, Dr. Nolan Williams, and mentor, Dr. David Spiegel, Dr. DeSouza is involved in investigating the effects of repetitive transcranial magnetic stimulation on hypnotic analgesia. Her overall research goal is to combine multimodal neuroimaging approaches to understand the basic mechanisms and biomarkers underlying pain phenotypes and chronic pain disorders to inform individual treatment strategies.

Dr. DeSouza is a Co-Director for the Neuroscience, Behavior, and Cognition (NBC) Scholarly Concentration, part of a required structured program of study in the medical student curriculum that promotes in depth learning and scholarship in this field. She is also a lecturer for the course ANES 215, a required course in the Department of Anesthesia for medical students enrolled in the NBC Scholarly Concentration.

Academic Appointments

Professional Education

  • Doctor of Philosophy, University of Toronto (2015)
  • Master of Science, University of Toronto (2009)
  • Bachelor of Science, University of Toronto (2006)


All Publications

  • High-dose spaced theta-burst TMS as a rapid-acting antidepressant in highly refractory depression. Brain : a journal of neurology Williams, N. R., Sudheimer, K. D., Bentzley, B. S., Pannu, J., Stimpson, K. H., Duvio, D., Cherian, K., Hawkins, J., Scherrer, K. H., Vyssoki, B., DeSouza, D., Raj, K. S., Keller, J., Schatzberg, A. F. 2018

    View details for DOI 10.1093/brain/awx379

    View details for PubMedID 29415152

  • Comparison of Diffusion-Weighted MRI Reconstruction Methods for Visualization of Cranial Nerves in Posterior Fossa Surgery. Frontiers in neuroscience Behan, B., Chen, D. Q., Sammartino, F., DeSouza, D. D., Wharton-Shukster, E., Hodaie, M. 2017; 11: 554


    Diffusion-weighted imaging (DWI)-based tractography has gained increasing popularity as a method for detailed visualization of white matter (WM) tracts. Different imaging techniques, and more novel, advanced imaging methods provide significant WM structural detail. While there has been greater focus on improving tract visualization for larger WM pathways, the relative value of each method for cranial nerve reconstruction and how this methodology can assist surgical decision-making is still understudied. Images from 10 patients with posterior fossa tumors (4 male, mean age: 63.5), affecting either the trigeminal nerve (CN V) or the facial/vestibular complex (CN VII/VIII), were employed. Three distinct reconstruction methods [two tensor-based methods: single diffusion tensor tractography (SDT) (3D Slicer), eXtended streamline tractography (XST), and one fiber orientation distribution (FOD)-based method: streamline tractography using constrained spherical deconvolution (CSD)-derived estimates (MRtrix3)], were compared to determine which of these was best suited for use in a neurosurgical setting in terms of processing speed, anatomical accuracy, and accurate depiction of the relationship between the tumor and affected CN. Computation of the tensor map was faster when compared to the implementation of CSD to provide estimates of FOD. Both XST and CSD-based reconstruction methods tended to give more detailed representations of the projections of CN V and CN VII/VIII compared to SDT. These reconstruction methods were able to more accurately delineate the course of CN V and CN VII/VIII, differentiate CN V from the cerebellar peduncle, and delineate compression of CN VII/VIII in situations where SDT could not. However, CSD-based reconstruction methods tended to generate more invalid streamlines. XST offers the best combination of anatomical accuracy and speed of reconstruction of cranial nerves within this patient population. Given the possible anatomical limitations of single tensor models, supplementation with more advanced tensor-based reconstruction methods might be beneficial.

    View details for DOI 10.3389/fnins.2017.00554

    View details for PubMedID 29062268

    View details for PubMedCentralID PMC5640769

  • Structural Magnetic Resonance Imaging Can Identify Trigeminal System Abnormalities in Classical Trigeminal Neuralgia FRONTIERS IN NEUROANATOMY DeSouza, D. D., Hodaie, M., Davis, K. D. 2016; 10


    Classical trigeminal neuralgia (TN) is a chronic pain disorder that has been described as one of the most severe pains one can suffer. The most prevalent theory of TN etiology is that the trigeminal nerve is compressed at the root entry zone (REZ) by blood vessels. However, there is significant evidence showing a lack of neurovascular compression (NVC) for many cases of classical TN. Furthermore, a considerable number of patients who are asymptomatic have MR evidence of NVC. Since there is no validated animal model that reproduces the clinical features of TN, our understanding of TN pathology mainly comes from biopsy studies that have limitations. Sophisticated structural MRI techniques including diffusion tensor imaging provide new opportunities to assess the trigeminal nerves and CNS to provide insight into TN etiology and pathogenesis. Specifically, studies have used high-resolution structural MRI methods to visualize patterns of trigeminal nerve-vessel relationships and to detect subtle pathological features at the trigeminal REZ. Structural MRI has also identified CNS abnormalities in cortical and subcortical gray matter and white matter and demonstrated that effective neurosurgical treatment for TN is associated with a reversal of specific nerve and brain abnormalities. In conclusion, this review highlights the advanced structural neuroimaging methods that are valuable tools to assess the trigeminal system in TN and may inform our current understanding of TN pathology. These methods may in the future have clinical utility for the development of neuroimaging-based biomarkers of TN.

    View details for DOI 10.3389/finana.2016.0095

    View details for Web of Science ID 000385677500001

    View details for PubMedID 27807409

  • Journal Club: Change in brain network connectivity during PACAP38-induced migraine attacks. Neurology DeSouza, D. D., O'Hare, M., Woldeamanuel, Y. W., Cowan, R. P. 2016; 87 (16): e199-e202

    View details for PubMedID 27754916

  • Journal Club: Exacerbation of headache during dihydroergotamine for chronic migraine does not alter outcome. Neurology Woldeamanuel, Y. W., O'Hare, M., DeSouza, D. D., Cowan, R. P. 2016; 87 (16): e196-e198


    Transient headache exacerbation during IV dihydroergotamine (DHE) therapy of migraine may prompt clinicians to prematurely discontinue DHE therapy, potentially depriving patients of the full benefit of DHE infusion. In a recent Neurology® article, Eller et al. evaluated whether or not worsening headache during DHE infusion was associated with suboptimal medium-term headache outcomes.

    View details for PubMedID 27754915

  • Reversal of insular and microstructural nerve abnormalities following effective surgical treatment for trigeminal neuralgia. Pain DeSouza, D. D., Davis, K. D., Hodaie, M. 2015; 156 (6): 1112–23


    Classical trigeminal neuralgia (TN) is a severe neuropathic facial pain disorder commonly associated with neurovascular compression at the trigeminal nerve root entry zone (REZ). Neurosurgical interventions can relieve TN pain, but the mechanisms underlying these effects are unknown. We determined whether the abnormalities we previously reported at the REZ of TN patients using diffusion tensor imaging (DTI) and brain gray matter (GM) analyses resolve after effective neurosurgical treatment. Twenty-five patients who underwent either microvascular decompression surgery or Gamma Knife radiosurgery for right-sided TN had magnetic resonance imaging scans before and after treatment and were compared with age-matched controls. Cortical thickness and voxel-based morphometry examined specific brain GM we previously reported as abnormal in TN. White matter metrics of fractional anisotropy (FA), mean, radial, and axial diffusivities (MD, RD, and AD, respectively) were extracted bilaterally from each trigeminal REZ. Before treatment, patients had widespread GM abnormalities including thinner ventral anterior insula (vAI) cortex, and REZ microstructural abnormalities (lower FA, and higher MD, RD, and AD) compared with controls. We considered a 75% reduction in pain as effective treatment. The right vAI was the only GM region that normalized toward the level of healthy controls after effective treatment. At the REZ, effective treatment reversed FA, MD, RD, and AD abnormalities and was correlated with pain relief after treatment. These results demonstrate that treatment can effectively resolve pain by normalizing REZ abnormalities, which may influence vAI abnormalities. Future studies should consider DTI as an adjunct to assess the patient outcome and subtle microstructural changes after treatment.

    View details for DOI 10.1097/j.pain.0000000000000156

    View details for PubMedID 25782366

  • Diffusivity signatures characterize trigeminal neuralgia associated with multiple sclerosis. Multiple sclerosis (Houndmills, Basingstoke, England) 2015


    Trigeminal neuralgia secondary to multiple sclerosis (MS-TN) is a facial neuropathic pain syndrome similar to classic trigeminal neuralgia (TN). While TN is caused by neurovascular compression of the fifth cranial nerve (CN V), how MS-related demyelination correlates with pain in MS-TN is not understood.We aim to examine diffusivities along CN V in MS-TN, TN, and controls in order to reveal differential neuroimaging correlates across groups.3T MR diffusion weighted, T1, T2 and FLAIR sequences were acquired for MS-TN, TN, and controls. Multi-tensor tractography was used to delineate CN V across cisternal, root entry zone (REZ), pontine and peri-lesional segments. Diffusion metrics including fractional anisotropy (FA), and radial (RD), axial (AD), and mean diffusivities (MD) were measured from each segment.CN V segments showed distinctive diffusivity patterns. The TN group showed higher FA in the cisternal segment ipsilateral to the side of pain, and lower FA in the ipsilateral REZ segment. The MS-TN group showed lower FA in the ipsilateral peri-lesional segments, suggesting differential microstructural changes along CN V in these conditions.The study demonstrates objective differences in CN V microstrucuture in TN and MS-TN using non-invasive neuroimaging. This represents a significant improvement in the methods currently available to study pain in MS.

    View details for DOI 10.1177/1352458515579440

    View details for PubMedID 25921052

  • Individual Differences in Temporal Summation of Pain Reflect Pronociceptive and Antinociceptive Brain Structure and Function. The Journal of neuroscience : the official journal of the Society for Neuroscience Cheng, J. C., Erpelding, N., Kucyi, A., DeSouza, D. D., Davis, K. D. 2015; 35 (26): 9689–9700


    Temporal summation of pain (TSP), the perception of increasingly greater pain evoked by repetitive noxious stimuli, is highly variable between individuals. Individuals with facilitated pain processing and/or reduced pain-modulatory capabilities are regarded as pronociceptive, whereas individuals with reduced pain processing capacity are characterized as antinociceptive. Brodmann area (BA) 3a of the primary somatosensory cortex is part of an ascending pathway from the sensory thalamus that mediates TSP. Descending pain modulation involves projections from the subgenual anterior cingulate cortex (sgACC) to the periaqueductal gray to the rostral ventromedial medulla (RVM). Here, we tested the hypothesis that pronociceptive individuals have an enhanced TSP response compared with antinociceptive individuals, marked by facilitated ascending nociceptive processing and/or reduced capacity for descending pain modulation. Eighty healthy humans were tested with a TSP protocol and underwent structural and resting-state functional magnetic resonance imaging. We found large interindividual differences in TSP responses, which were positively correlated with functional connectivity (FC) between individuals' right sensory thalamus with their BA 3a (thal-BA 3a), and with cortical thickness in their insula and medial prefrontal cortex. In contrast, TSP was negatively correlated with FC between individuals' RVM with their sgACC (RVM-sgACC). When subjects were grouped as pronociceptive or antinociceptive based on whether they had greater thal-BA 3a or RVM-sgACC FC respectively, pronociceptive subjects showed greater TSP responses. Furthermore, TSP was positively correlated with the extent of imbalance toward ascending nociceptive processing. Our study indicates that individuals with enhanced TSP have facilitated ascending nociceptive processing and reduced pain-modulatory capacities.This study provides novel evidence that an individual's propensity to experience amplified pain with repeated stimuli [i.e., temporal summation of pain (TSP)] reflects attributes of their "pain connectome," namely stronger ascending nociceptive and weaker descending pain-modulatory components. Understanding the individual neural mechanisms underlying TSP within individuals has implications for developing personalized pain-management strategies for chronic pain.

    View details for DOI 10.1523/JNEUROSCI.5039-14.2015

    View details for PubMedID 26134651

  • Discriminating neural representations of physical and social pains: how multivariate statistics challenge the 'shared representation' theory of pain. Journal of neurophysiology 2015: jn.00075.2015


    Overlapping functional magnetic resonance imaging (fMRI) activity elicited by physical pain and social rejection has posited a common neural representation between the two experiences. However, Woo and colleagues (Woo et al., 2014) recently used multivariate statistics to challenge the 'shared representation' theory of pain. This study has implications in the way results from fMRI studies are interpreted, and has the potential of broadening our understanding of different pain states and future development of personalized medicine.

    View details for DOI 10.1152/jn.00075.2015

    View details for PubMedID 25787949

  • Diffusion imaging in trigeminal neuralgia reveals abnormal trigeminal nerve and brain white matter. Pain DeSouza, D. D., Hodaie, M., Davis, K. D. 2014; 155 (9): 1905-1906

    View details for DOI 10.1016/j.pain.2014.05.026

    View details for PubMedID 24880116

  • Abnormal trigeminal nerve microstructure and brain white matter in idiopathic trigeminal neuralgia. Pain DeSouza, D. D., Hodaie, M., Davis, K. D. 2014; 155 (1): 37-44


    Idiopathic trigeminal neuralgia (TN) is classically associated with neurovascular compression (NVC) of the trigeminal nerve at the root entry zone (REZ), but NVC-induced structural alterations are not always apparent on conventional imaging. Previous studies report lower fractional anisotropy (FA) in the affected trigeminal nerves of TN patients using diffusion tensor imaging (DTI). However, it is not known if TN patients have trigeminal nerve abnormalities of mean, radial, or axial diffusivity (MD, RD, AD - metrics linked to neuroinflammation and edema) or brain white matter (WM) abnormalities. DTI scans in 18 right-sided TN patients and 18 healthy controls were retrospectively analyzed to extract FA, RD, AD, and MD from the trigeminal nerve REZ, and Tract-Based Spatial Statistics (TBSS) was used to assess brain WM. In patients, the affected trigeminal nerve had lower FA, and higher RD, AD, and MD was found bilaterally compared to controls. Group TBSS (P<0.05, corrected) showed patients had lower FA and increased RD, MD, and AD in brain WM connecting areas involved in the sensory and cognitive-affective dimensions of pain, attention, and motor functions, including the corpus callosum, cingulum, posterior corona radiata, and superior longitudinal fasciculus. These data indicate that TN patients have abnormal tissue microstructure in their affected trigeminal nerves, and as a possible consequence, WM microstructural alterations in the brain. These findings suggest that trigeminal nerve structural abnormalities occur in TN, even if not apparent on gross imaging. Furthermore, MD and RD findings suggest that neuroinflammation and edema may contribute to TN pathophysiology.

    View details for DOI 10.1016/j.pain.2013.08.029

    View details for PubMedID 23999058

  • Sensorimotor and Pain Modulation Brain Abnormalities in Trigeminal Neuralgia: A Paroxysmal, Sensory-Triggered Neuropathic Pain. PloS one 2013; 8 (6): e66340


    Idiopathic trigeminal neuralgia (TN) is characterized by paroxysms of severe facial pain but without the major sensory loss that commonly accompanies neuropathic pain. Since neurovascular compression of the trigeminal nerve root entry zone does not fully explain the pathogenesis of TN, we determined whether there were brain gray matter abnormalities in a cohort of idiopathic TN patients. We used structural MRI to test the hypothesis that TN is associated with altered gray matter (GM) in brain areas involved in the sensory and affective aspects of pain, pain modulation, and motor function. We further determined the contribution of long-term TN on GM plasticity.Cortical thickness and subcortical GM volume were measured from high-resolution 3T T1-weighted MRI scans in 24 patients with right-sided TN and 24 healthy control participants.TN patients had increased GM volume in the sensory thalamus, amygdala, periaqueductal gray, and basal ganglia (putamen, caudate, nucleus accumbens) compared to healthy controls. The patients also had greater cortical thickness in the contralateral primary somatosensory cortex and frontal pole compared to controls. In contrast, patients had thinner cortex in the pregenual anterior cingulate cortex, the insula and the orbitofrontal cortex. No relationship was observed between GM abnormalities and TN pain duration.TN is associated with GM abnormalities in areas involved in pain perception, pain modulation and motor function. These findings may reflect increased nociceptive input to the brain, an impaired descending modulation system that does not adequately inhibit pain, and increased motor output to control facial movements to limit pain attacks.

    View details for DOI 10.1371/journal.pone.0066340

    View details for PubMedID 23823184

  • Making Sense of Gray Matter Abnormalities in Chronic Orofacial Pain-Synthesizing Divergent Findings JOURNAL OF NEUROSCIENCE Moayedi, M., DeSouza, D., Erpelding, N. 2011; 31 (35): 12396-12397
  • Use of Diffusion Tensor Imaging to Examine Subacute White Matter Injury Progression in Moderate to Severe Traumatic Brain Injury ARCHIVES OF PHYSICAL MEDICINE AND REHABILITATION Greenberg, G., Mikulis, D. J., Ng, K., DeSouza, D., Green, R. E. 2008; 89 (12): S45-S50


    To demonstrate subacute progression of white matter (WM) injury (4.5mo-2.5y postinjury) in patients with traumatic brain injury using diffusion-tensor imaging.Prospective, repeated-measures, within-subjects design.Inpatient neurorehabilitation program and teaching hospital MRI department.Brain-injured adults (N=13) with a mean Glasgow Coma Scale score of 7.67+/-4.16.Not applicable.Fractional anisotropy (FA) values were measured at 4.5 and 29 months postinjury in right and left frontal and temporal deep WM tracts and the anterior and posterior corpus callosum.FA significantly decreased in frontal and temporal tracts: right frontal (.38+/-.06 to .30+/-.06; P<.005), left frontal (.37+/-.06 to .32+/-.06; P<.05), right temporal (.28+/-.05 to .22+/-.018; P<.005), and left temporal (.28+/-.05 to .24+/-.02; P<.05). No significant changes were in the corpus callosum.Preliminary results demonstrate progression of WM damage as evidenced by interval changes in diffusion anisotropy. Future research should examine the relationship between decreased FA and long-term clinical outcome.

    View details for DOI 10.1016/j.apmr.2008.08.211

    View details for Web of Science ID 000261999400006

    View details for PubMedID 19081441