Bio

Clinical Focus


  • Multiple Sclerosis
  • Electromyography
  • Neurology

Academic Appointments


Administrative Appointments


  • Director, Residency Program in Clinical Neurophysiology (1995 - 2013)
  • Director, Stanford Neurodiagnostic Laboratories (1994 - 2013)
  • Director, SHC/LPCH Evoked Potential Laboratories (1991 - 2013)
  • Director, SHC/LPCH Electromyography Laboratories (1991 - 2013)
  • Director, Stanford Multiple Sclerosis Clinic (1974 - Present)

Honors & Awards


  • President, American Association for Electrodiagnostic Medicine (1997-98)
  • President, AAEM Foundation for Research and Education (1997-98)
  • Director, American Board of Electrodiagnostic Medicine (1999-2005)
  • President, Association of California Neurologists (2002-04)

Professional Education


  • Fellowship:Mayo Clinic (1974) AZ
  • Residency:Greenwich Hospital (1970) CT
  • Residency:Stanford University School of Medicine (1973) CA
  • Internship:Greenwich Hospital (1969) CT
  • Medical Education:Albert Einstein College of Medicine (1968) NY
  • Board Certification: Neurology, American Board of Psychiatry and Neurology (1975)
  • Fellowship:National Hospital (1974) UKEngland
  • BSc, McGill University, Physiological Psychology (1964)
  • MD, Albert Einstein, Medicine (1968)

Community and International Work


  • NMSS Clinical Advisory Board, Santa Clara County

    Topic

    Multiple Sclerosis

    Partnering Organization(s)

    National MS Society, Northern CA Chapter

    Populations Served

    Patients with MS and their Families

    Location

    Bay Area

    Ongoing Project

    Yes

    Opportunities for Student Involvement

    No

  • ACN Board of Directors -Consultant, Sacramento

    Topic

    Neurological Disorders

    Partnering Organization(s)

    Association of California Neurologists

    Populations Served

    Patients with neurological diseases and their families

    Location

    California

    Ongoing Project

    Yes

    Opportunities for Student Involvement

    No

Research & Scholarship

Current Research and Scholarly Interests


Clinical electrophysiology of the peripheral and central nervous systems, including nerve conduction velocity; electromyography (EMG); and visual, auditory and somatosensory evoked potentials. Application of digital signal processing techniques in clinical neurophysiology for diagnosis of neurological disorders and for neurological rehabilitation. Multiple sclerosis (MS) diagnosis and treatment. Implementation of new methodologies for teaching clinical neuroscience to undergraduate, graduate and medical students, residents and fellows.

Teaching

2013-14 Courses


Graduate and Fellowship Programs


Publications

Journal Articles


  • Moyamoya Disease Can Masquerade as Multiple Sclerosis NEUROLOGIST Dorfman, L. J., Fischbein, N. J., Woodard, J. I., Choudhri, O., Bell-Stephens, T. E., Steinberg, G. K. 2012; 18 (6): 398-403

    Abstract

    Moyamoya disease (MM) is a rare disorder of the cerebral arterial circulation, whereas multiple sclerosis (MS) is a relatively common immune-mediated attack on central myelin. Despite the differences in pathogenesis, the 2 disorders share some clinical features which can lead to diagnostic confusion: both can affect young adults, cause intermittent neurological symptoms, and show multifocal abnormalities on brain imaging.To emphasize the need for early consideration of MM in the differential diagnosis of MS-spectrum disorders.Chart reviews and individual case analyses.We present detailed descriptions of 3 patients with MM, and summary data on 8 additional cases, in which there was diagnostic confusion with MS, with delays in treatment ranging from 2 months to 19 years (median=4 y).MM can be misdiagnosed as MS, leading to delay in correct treatment. We highlight the clinical and radiologic features which allow differentiation of these conditions early in the course, when treatment can have maximum benefit.

    View details for DOI 10.1097/NRL.0b013e31826a99a1

    View details for Web of Science ID 000310628800012

    View details for PubMedID 23114675

  • Neuroradiologic Correlates of Cognitive Impairment in Adult Moyamoya Disease AMERICAN JOURNAL OF NEURORADIOLOGY Mogensen, M. A., Karzmark, P., Zeifert, P. D., Rosenberg, J., Marks, M., Steinberg, G. K., Dorfman, L. J. 2012; 33 (4): 721-725

    Abstract

    MMD has been shown to result in impairment of executive functioning in adults. The purpose of this study was to correlate presurgical neuropsychological assessments with the severity of primary MMD as measured by CBF and CVR and with secondary damage from MMD as estimated by cortical stroke and WMD.A retrospective analysis of 31 adult patients with MMD was performed. Xe-CT was used to obtain CBF and CVR, and MRI was reviewed to grade cortical stroke and WMD. Two tests of executive functioning (FAS and TMT-B) were correlated with imaging findings. A multiple regression analysis was performed.There was a significant overall positive relationship between mean CBF and FAS (P = .038) and TMT-B scores (P = .014). A significant negative relationship was present between the WMD score and the FAS (P = .009) and TMT-B scores (P = .015). Per-region analysis demonstrated that FAS and TMT-B scores were significantly decreased by the presence of a posterior stroke (P < .0001 and P = .001) or WMD (P = .006 and P = .004). All patients with posterior parieto-occipital WMD or stroke also had secondary disease in the anterior regions.Impaired executive functioning in adults with MMD is most strongly associated secondary damage in the form of WMD or cortical stroke. The effect is most profound with parieto-occipital lobe involvement, likely a reflection of overall disease severity. Increasing global WMD burden may be a better indicator of cognitive decline than cortical infarction. Patients with higher baseline CBF seem to have better cognitive functioning.

    View details for DOI 10.3174/ajnr.A2852

    View details for Web of Science ID 000302842900024

    View details for PubMedID 22173751

  • Neurocognitive Impairment in Adults With Moyamoya Disease Without Stroke NEUROSURGERY Karzmark, P., Zeifert, P. D., Bell-Stephens, T. E., Steinberg, G. K., Dorfman, L. J. 2012; 70 (3): 634-638

    Abstract

    Adults with moyamoya disease (MMD) have been shown to manifest cognitive impairment, but it is unclear whether this is the result of ischemic stroke.To determine whether adults with MMD but without stroke have cognitive impairment.We performed detailed neuropsychological assessments in 30 adults with angiographically confirmed MMD without magnetic resonance imaging (MRI) evidence of stroke.Twenty patients (67%) exhibited small T2 hyperintensities in the cerebral subcortical white matter on brain MRI but no evidence of gray matter damage. Significant cognitive impairment, defined as half of test scores ? 1 SD below the normal mean, was present in 7 patients (23%). Executive functioning, mental efficiency, and word finding were the ability areas most frequently impaired, whereas memory was relatively intact. Clinically significant emotional distress (depression and/or anxiety) was present in 11 patients (37%). Comparable cognitive findings were also observed in the subset of 10 patients (33%) with completely normal static brain MRI.Cognitive impairment in MMD can occur in the absence of ischemic stroke as manifested on MRI.

    View details for DOI 10.1227/NEU.0b013e3182320d1a

    View details for Web of Science ID 000300781700020

    View details for PubMedID 21849919

  • Effect of moyamoya disease on neuropsychological functioning in adults NEUROSURGERY Karzmark, P., Zeifert, P. D., Tan, S., Dorfman, L. J., Bell-Stephens, T. E., Steinberg, G. K. 2008; 62 (5): 1048-1051

    Abstract

    Moyamoya disease is a cerebrovascular disorder characterized by progressive occlusion of vessels comprising the circle of Willis, resulting in formation of collaterals that have a cloudy appearance on angiography. Neuropsychological research on the cognitive effects of the disorder in adults has been limited in scope and generalizability; only a few case studies have been published. The current study was intended to more comprehensively document the nature of cognitive impairment in moyamoya disease by assessing a large number of adult cases with a neuropsychological assessment test battery.Thirty-six adult patients with neurodiagnostically confirmed moyamoya disease were given presurgical neuropsychological assessments.Mean group performances were within normal limits for all measures assessed. The highest rate of impairment was for measures of executive functioning. The lowest rates occurred with memory and perception measures. Cognitive impairment was present in 11 (31%) of the patients; it was judged to be moderate to severe in four patients (11%). Five patients reported a mild level of depression, and two patients reported a moderate level.The present findings suggest that moyamoya disease diagnosed in adults can impair cognition but that the effect is not as severe as in pediatric cases. Executive functioning is most affected. Memory and, to a large extent, intellect are spared. The current pattern of results suggests brain region-behavior correlations that deserve further study.

    View details for DOI 10.1227/01.NEU.0000312712.55567.E6

    View details for Web of Science ID 000257218500011

    View details for PubMedID 18580802

  • AAEM minimonograph #47: Normative data in electrodiagnostic medicine MUSCLE & NERVE DORFMAN, L. J., Robinson, L. R. 1997; 20 (1): 4-14

    Abstract

    This article reviews, without mathematics, the important principles governing the acquisition and use of normative data in electrodiagnostic medicine. Common flaws in neurophysiological normative data include vague clinical criteria for establishing freedom from disease, samples that are too small and inadequately stratified, and application of Gaussian statistics to non-Gaussian variables. Other problematic issues concern the trade-off between permissible false-positivity and false-negativity in defining the limits of normative from sample data, test-retest variability, and the use of multiple independent test measurements in each electrodiagnostic examination. The following standards for normative data are proposed: (1) standardized objective determination of freedom from disease; (2) appropriately large sample of normal subjects; (3) proportional statification of normal subjects for known relevant variables; (4) test of Gaussian fit for application of Gaussian statistics; and (5) data presentation by percentiles when Gaussian fit is in doubt. Many existing normative studies in clinical neurophysiology do not meet these standards. High-quality normative data, readily accessible, is essential for the accurate electrodiagnosis of neuromuscular diseases.

    View details for Web of Science ID A1997VZ33200003

    View details for PubMedID 8995577

  • A COMPARISON OF TURNS ANALYSIS AND MOTOR UNIT ANALYSIS IN ELECTROMYOGRAPHY ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY McGill, K. C., Lau, K., DORFMAN, L. J. 1991; 81 (1): 8-17

    Abstract

    We compared the results of turns analysis and motor unit analysis on 4056 electromyographic interference patterns (IPs) from normal subjects and patients with neuromuscular disorders. The motor unit analysis involved decomposing the IPs into their component motor unit action potentials (MUAPs) using automatic decomposition electromyography (ADEMG). We checked the accuracy of the decompositions by attempting to reconstruct some of the IPs from their identified MUAPs using computer simulations. The simulations revealed that ADEMG typically identified more than 60% (but not all) of the MUAPs in a given IP. Both turns and MUAP properties showed regular and related changes with force, age, muscle, and recording electrode type. The number of turns in each IP was highly correlated with the number of active MUAPs (r = 0.65), the mean MUAP firing rate (r = 0.72), the mean number of turns per MUAP (r = 0.34), and the product of these 3 properties (r = 0.83). The mean amplitude change per turn was highly correlated with the mean MUAP amplitude (r = 0.82), but also depended on the number of turns per MUAP. Due to the lack of a one-to-one relationship between the turns analysis properties and the MUAP properties, the turns analysis properties by themselves did not provide sufficient information to infer unambiguous physiological information about motor unit morphology or firing behavior.

    View details for Web of Science ID A1991FA30100002

    View details for PubMedID 1705223

  • POLYNEUROPATHY, OPHTHALMOPLEGIA, LEUKOENCEPHALOPATHY, AND INTESTINAL PSEUDOOBSTRUCTION - POLIP SYNDROME ANNALS OF NEUROLOGY SIMON, L. T., Horoupian, D. S., DORFMAN, L. J., Marks, M., Herrick, M. K., Wasserstein, P., Smith, M. E. 1990; 28 (3): 349-360

    Abstract

    We describe 5 individuals (from three separate families) with a progressive neurological disorder characterized by sensorimotor peripheral polyneuropathy, cranial neuropathies (external ophthalmoplegia, deafness), and the syndrome of chronic intestinal pseudo-obstruction. Magnetic resonance imaging showed widespread abnormality of the cerebral and cerebellar white matter in the 2 patients studied. Autopsy examination in 3 revealed widespread endoneurial fibrosis and demyelination in the peripheral nervous system, possibly secondary to axonal atrophy, and poorly defined changes in cerebral white matter (leukoencephalopathy). The cranial nerves and spinal roots were less severely involved and the neurons in the brainstem and spinal cord were intact. The fatal gastrointestinal dysmotility was due to a severe visceral neuropathy. We suggest that these patients manifested a hereditary disorder with distinctive clinical, radiological, and neuropathological features, and propose the acronym POLIP to emphasize the distinctive tetrad of polyneuropathy, ophthalmoplegia, leukoencephalopathy, and intestinal pseudo-obstruction.

    View details for Web of Science ID A1990DZ68600007

    View details for PubMedID 2173474

  • TRIPHASIC BEHAVIORAL-RESPONSE OF MOTOR UNITS TO SUBMAXIMAL FATIGUING EXERCISE MUSCLE & NERVE DORFMAN, L. J., Howard, J. E., McGill, K. C. 1990; 13 (7): 621-628

    Abstract

    We have measured the firing rate and amplitude of 4551 motor unit action potentials (MUAPs) recorded with concentric needle electrodes from the brachial biceps muscles of 10 healthy young adults before, during, and after 45 minutes of intermittent isometric exercise at 20% of maximum voluntary contraction (MVC), using an automatic method for decomposition of electromyographic activity (ADEMG). During and after exercise, MUAPs derived from contractions of 30% MVC showed progressive increase in mean firing rate (P less than or equal to .01) and amplitude (P less than or equal to .05). The firing rate increase preceded the rise in mean amplitude, and was evident prior to the development of fatigue, defined as reduction of MVC. Analysis of individual potentials revealed that the increase in firing rate and in amplitude reflected different MUAP subpopulations. A short-term (less than 1 minute) reduction in MUAP firing rates (P less than or equal to .05) was also observed at the onset of each test contraction. These findings suggest that motor units exhibit a triphasic behavioral response to prolonged submaximal exercise: (1) short-term decline and stabilization of onset firing rates, followed by (2) gradual and progressive increase in firing rates and firing variability, and then by (3) recruitment of additional (larger) motor units. The (2) and (3) components presumably compensate for loss of force-generating capacity in the exercising muscle, and give rise jointly to the well-known increase in total surface EMG which accompanies muscle fatigue.

    View details for Web of Science ID A1990DL33300010

    View details for PubMedID 2388662

  • MOTOR UNIT FIRING RATES AND FIRING RATE VARIABILITY IN THE DETECTION OF NEUROMUSCULAR DISORDERS ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY DORFMAN, L. J., Howard, J. E., McGill, K. C. 1989; 73 (3): 215-224

    Abstract

    We have used automatic decomposition electromyography (ADEMG) to study 41 muscles in 29 patients with well-defined peripheral and central motor disorders. In motor neuron diseases motor unit action potentials (MUAPs) showed increased amplitudes, firing rates and firing variability. Relatively large MUAPs sometimes were not identified by the computer program if they lacked sufficient high-frequency signal content, or were too variable in shape. In myopathies the MUAPs showed reduced amplitudes, durations and turns, and sometimes dramatic increases in firing rates. Also, the mean number of MUAPs per recording site was often increased, indicating excessive recruitment. In polymyositis (the best studied myopathy) the nature and magnitude of the MUAP shape and firing abnormalities were usually similar at different levels of contractile force, suggesting that motor units are affected without regard to recruitment order. In upper motor neuron paresis (multiple sclerosis), the shape properties of the MUAPs were normal, but mean firing rates were reduced, and firing variability increased. These findings confirm many of the traditional criteria for distinguishing neurogenic from myopathic disease electrophysiologically at the level of the individual MUAP. In addition, they demonstrate the potential diagnostic sensitivity of MUAP firing rate measurements for detecting neuromuscular dysfunction, and for differentiating between some cases of central and peripheral paresis, but not for distinguishing peripheral neurogenic from myopathic weakness, since firing rates tend to increase in both. Increased firing rate variability may be a marker of central or peripheral neurogenic weakness.

    View details for Web of Science ID A1989AP90300005

    View details for PubMedID 2475326

  • PROPERTIES OF MOTOR UNIT ACTION-POTENTIALS RECORDED WITH CONCENTRIC AND MONOPOLAR NEEDLE ELECTRODES - ADEMG ANALYSIS MUSCLE & NERVE Howard, J. E., DORFMAN, L. J. 1988; 11 (10): 1051-1055

    Abstract

    We compared the configurational and firing properties of 7270 motor unit action potentials (MUAPs) recorded with either concentric (CNE) or monopolar (MNE) needle electrodes from the brachial biceps and anterior tibial muscles of 10 healthy young adults (mean age 27 +/- 4.5 years) using automatic decomposition electromyography (ADEMG). In both muscles, mean MUAP amplitude, rise rate, and number of turns were significantly greater when recorded with MNE (paired t-test, P less than 0.001 in each case). Similar findings were observed at all three tested levels of isometric contractile force: threshold, 10% of maximum voluntary contraction (MVC), and 30% MVC. In contrast, there was no significant difference between electrode types on measurements of mean MUAP duration or firing rate (P greater than 0.05 in each case). These findings indicate that it is acceptable to generalize normative data on MUAP duration and firing rate from one electrode type to another, but that measures of MUAP amplitude and complexity require independent normative databases.

    View details for Web of Science ID A1988Q349800006

    View details for PubMedID 3185599

  • INFLUENCE OF CONTRACTILE-FORCE ON PROPERTIES OF MOTOR UNIT ACTION-POTENTIALS - ADEMG ANALYSIS JOURNAL OF THE NEUROLOGICAL SCIENCES DORFMAN, L. J., Howard, J. E., McGill, K. C. 1988; 86 (2-3): 125-136

    Abstract

    We have used automatic decomposition electromyography (ADEMG) to measure the configurational and firing properties of 13,206 motor unit action potentials (MUAPs) in the brachial biceps, brachial triceps and anterior tibial muscles of 30 healthy adults (22 men, 8 women; mean age 48.6 +/- 16.9 years, range 20-76) at three levels of isometric contractile force: threshold, 10% of maximum voluntary contraction (MVC), and 30% MVC. In all muscles, the increment in contractile force from threshold to 10% MVC was associated with a significant (P less than 0.05, paired t-test) increase in mean MUAP firing rate and number of turns per MUAP. The increment from 10% to 30% MVC led to highly significant (P less than 0.005) increase in mean firing rate, number of turns, amplitude and rise rate. Each force increment was associated with an increase in the number of simultaneously-active MUAPs per recording site; and with a significant decrease in mean MUAP duration in all muscles, due to noise-dependency of the duration measurement. Quantitatively, the changes in MUAP properties with force were comparable to or exceeded the effects of age, gender differences, or intermuscular variability. Test-retest measurements 2 years apart in a subgroup of young adults showed good correspondence of mean MUAP properties with force standardization. These results demonstrate that contractile force is a major determinant of MUAP shape and behavior properties, and so must be precisely measured or controlled in clinical EMG studies.

    View details for Web of Science ID A1988Q297800002

    View details for PubMedID 3221235

  • AGE EFFECTS ON PROPERTIES OF MOTOR UNIT ACTION-POTENTIALS - ADEMG ANALYSIS ANNALS OF NEUROLOGY Howard, J. E., McGill, K. C., DORFMAN, L. J. 1988; 24 (2): 207-213

    Abstract

    We have measured the configurational and firing properties of 13,206 motor unit action potentials (MUAPs) from the brachial biceps, brachial triceps, and anterior tibial muscles in 10 young (20-40 years), 10 middle-aged (40-60 years), and 10 elderly (60-80 years) normal individuals, using an automatic method for decomposition of the electromyographic (EMG) interference pattern (ADEMG). Recording were made during stable isometric contractions at threshold, 10%, and 30% of maximum voluntary contraction using standard concentric needle electrodes. At supra-threshold forces, an average of 5.9 simultaneously active MUAPs were identified at each recording site. Mean amplitudes, durations, and numbers of turns all increased linearly with age in both low-threshold and high-threshold MUAPs (p less than 0.01), suggesting an ongoing process of progressive denervation and compensatory reinnervation. Mean MUAP firing rates decreased with age (p = 0.01) when force was measured proportionately, but not when measured absolutely. In a subgroup of 12 age-matched gender pairs, men had larger mean MUAP amplitudes, rise rates, and numbers of turns (p less than 0.05), probably reflecting larger muscle fiber diameters. These findings amplify previous observations from traditional analysis of lowest-threshold single MUAPs; establish a base of normative adult data for ADEMG; and further validate the clinical applicability of rapid, automatic EMG decomposition.

    View details for Web of Science ID A1988P624700005

    View details for PubMedID 3178176

  • AAEE MINIMONOGRAPH .29. AUTOMATIC QUANTITATIVE ELECTROMYOGRAPHY MUSCLE & NERVE DORFMAN, L. J., McGill, K. C. 1988; 11 (8): 804-818

    Abstract

    The present status of different computerized methods of automatic quantitative electromyography are reviewed. Interference pattern methods-turns analysis, spectral analysis-are efficient, but the results usually cannot be directly related to the physiological properties of the motor units. Integration analysis does not currently have a major role in diagnostic electromyography. Traditional measurement of single motor unit action potentials during weak contraction can be facilitated and made more objective with computer assistance, but only the lowest-threshold motor units in the muscle are amenable to study. A new class of methodologies under development permit the decomposition of interference patterns into their constituent motor unit action potentials for measurement of configurational and behavioral properties. Patient data from these various methods can be statistically compared with normative data bases available on-line in computerized electromyographs. Both quantitative and quantitative electromyography have applications in the neuromuscular electrodiagnostic examination.

    View details for Web of Science ID A1988P575700002

    View details for PubMedID 3050509

  • Computer analysis of compound action potentials. Electroencephalography and clinical neurophysiology. Supplement DORFMAN, L. J. 1987; 39: 33-37

    View details for PubMedID 3477443

  • LEBERS DISEASE AND DYSTONIA - A MITOCHONDRIAL DISEASE NEUROLOGY Novotny, E. J., Singh, G., Wallace, D. C., DORFMAN, L. J., Louis, A., SOGG, R. L., Steinman, L. 1986; 36 (8): 1053-1060

    Abstract

    We studied a kindred in which 8 members had the neuroretinopathy of Leber's disease; 14 had a progressive, generalized dystonia attributed to striatal degeneration; and 1 had both disorders. The mode of inheritance was compatible with maternal transmission. This neurologic disorder may be a mitochondrial disease.

    View details for Web of Science ID A1986D492700007

    View details for PubMedID 3736869

  • EVOKED-POTENTIALS IN HYSTERIA AND MALINGERING JOURNAL OF CLINICAL NEUROPHYSIOLOGY Howard, J. E., DORFMAN, L. J. 1986; 3 (1): 39-49

    Abstract

    Evoked potentials are often helpful in confirming the nonorganic nature of sensory symptoms in hysteria and malingering. In a retrospective analysis, such cases were found to comprise approximately 1% of referrals to a university hospital laboratory. However, the diagnostic usefulness of electrophysiologic tests is limited in some clinical settings: normal responses may be encountered in subjects with certain organic deficits, and "abnormal" responses can sometimes be produced voluntarily by normal subjects. In malingering--as opposed to hysteria--the role of the technologist in monitoring patient compliance with the test procedure is particularly important. Like other laboratory investigations, evoked potential findings must be interpreted within the context of each clinical situation, and with full appreciation of the sensitivities and specificities of the tests.

    View details for Web of Science ID A1986AXJ5400003

    View details for PubMedID 3949967

  • AUTOMATIC DECOMPOSITION OF THE CLINICAL ELECTROMYOGRAM IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING McGill, K. C., Cummins, K. L., DORFMAN, L. J. 1985; 32 (7): 470-477

    View details for Web of Science ID A1985AKN9100002

    View details for PubMedID 3839488

  • AUTOMATIC DECOMPOSITION ELECTROMYOGRAPHY (ADEMG) - VALIDATION AND NORMATIVE DATA IN BRACHIAL BICEPS ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY McGill, K. C., DORFMAN, L. J. 1985; 61 (5): 453-461

    Abstract

    We describe a new, automatic method (ADEMG) for decomposing EMG interference patterns into their constituent motor unit action potentials (MUAPs), and quantitating the configurational and firing properties of the MUAPs. ADEMG is fast (90 sec analysis time for a 10 sec EMG epoch) and efficient (33-98% of MUAP occurrences correctly identified) because of 4 signal-processing innovations designated digital prefiltering, high-resolution wave form alignment, firing-time analysis and interference-cancellation averaging. Validation experiments are described involving recruitment/derecruitment of low-threshold MUAPs, and single-fiber-triggered averaging. Normative data are presented for 2000 MUAPs from brachial biceps (mean 9.7 MUAPs per site) at 3 levels of isometric contraction (7%, 15% and 30% MVC) and contrasted with normal findings obtained using traditional, low-threshold MUAP analysis. The main advantages of ADEMG are speed of data acquisition and processing in the clinical setting; ability to analyze both low- and high-threshold MUAPs during moderately strong muscular contractions; and MUAP firing-rate information.

    View details for Web of Science ID A1985AUC7000016

    View details for PubMedID 2412799

  • AAEE MINIMONOGRAPH-21 - THE DISTRIBUTION OF CONDUCTION VELOCITIES (DCV) IN PERIPHERAL-NERVES - A REVIEW MUSCLE & NERVE DORFMAN, L. J. 1984; 7 (1): 2-11
  • HIGH-RESOLUTION ALIGNMENT OF SAMPLED WAVEFORMS IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING McGill, K. C., DORFMAN, L. J. 1984; 31 (6): 462-468

    View details for Web of Science ID A1984SS50200004

    View details for PubMedID 6735418

  • NEUROPATHY IN THE HYPEREOSINOPHILIC SYNDROME MUSCLE & NERVE DORFMAN, L. J., Ransom, B. R., Forno, L. S., KELTS, A. 1983; 6 (4): 291-298

    Abstract

    Peripheral nerve dysfunction was a prominent clinical feature in each of three patients with the hypereosinophilic syndrome (HES). The neuropathy, occurring at the onset of marked eosinophilia or at a time of its worsening, had a painful onset, evolved over 1-4 weeks, and affected both sensory and motor function. Electrodiagnostic studies demonstrated both multifocal and generalized nerve involvement, with the former predominating (multiple mononeuropathy). Nerve and muscle biopsies from two patients revealed severe axonal degeneration with neurogenic atrophy of muscle. The eosinophilia decreased dramatically with corticosteroid treatment and the neuropathy gradually improved, but all three patients manifested residual neurologic disability 17-22 months after onset. The neuropathy may be on an ischemic basis or may be related to neurotoxicity of eosinophil products.

    View details for Web of Science ID A1983QR36400007

    View details for PubMedID 6866008

  • SENSORY EVOKED-POTENTIALS - CLINICAL-APPLICATIONS IN MEDICINE ANNUAL REVIEW OF MEDICINE DORFMAN, L. J. 1983; 34: 473-489

    View details for Web of Science ID A1983QJ82600035

    View details for PubMedID 6344773

  • ON THE NATURE AND ELIMINATION OF STIMULUS ARTIFACT IN NERVE SIGNALS EVOKED AND RECORDED USING SURFACE ELECTRODES IEEE TRANSACTIONS ON BIOMEDICAL ENGINEERING McGill, K. C., Cummins, K. L., DORFMAN, L. J., BERLIZOT, B. B., LUETKEMEYER, K., Nishimura, D. G., Widrow, B. 1982; 29 (2): 129-137

    View details for Web of Science ID A1982MY71300009

    View details for PubMedID 7056556

  • TRAUMATIC LESIONS OF THE PONTOMEDULLARY JUNCTION NEUROSURGERY BRITT, R. H., Herrick, M. K., Mason, R. T., DORFMAN, L. J. 1980; 6 (6): 623-631

    Abstract

    An autopsied series of 162 consecutive fatal head injuries was analyzed for location and type of primary brain stem injury. Of 41 cases with primary brain stem injury, 24 (59%) demonstrated 22 tears and 2 complete transections at the level of the pontomedullary junction. Three cases are presented in detail to illustrate the range of structural and functional damage seen with trauma at this level of the brain stem. A pathologically verified case of traumatic "locked-in" syndrome is reported, including serial brain stem auditory evoked responses that are correlated with the neuropathological findings. In addition, two cases of primary traumatic damage at the pontomedullary junction (one tear and one total transection) are described; these were associated with instantaneous death at the time of injury. Pathophysiologically, the tearing or disruption occurring at this level results from rapid hyperextension, which produces stretching at the pontomedullary junction.

    View details for Web of Science ID A1980JY93900002

    View details for PubMedID 7432604

  • PERIPHERAL NEUROPATHY IN THE CHERRY-RED SPOT-MYOCLONUS SYNDROME (SIALIDOSIS TYPE-I) ANNALS OF NEUROLOGY Steinman, L., Tharp, B. R., DORFMAN, L. J., Forno, L. S., SOGG, R. L., KELTS, K. A., OBRIEN, J. S. 1980; 7 (5): 450-456

    View details for Web of Science ID A1980JT26000008

    View details for PubMedID 6249183

  • SENSORY EVOKED-POTENTIALS - CLINICAL-APPLICATIONS IN PEDIATRICS JOURNAL OF PEDIATRICS Mizrahi, E. M., DORFMAN, L. J. 1980; 97 (1): 1-10

    View details for Web of Science ID A1980JY86700001

    View details for PubMedID 7381627

  • NERVE-FIBER CONDUCTION-VELOCITY DISTRIBUTIONS .1. ESTIMATION BASED ON THE SINGLE-FIBER AND COMPOUND ACTION POTENTIALS ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY Cummins, K. L., PERKEL, D. H., DORFMAN, L. J. 1979; 46 (6): 634-646

    Abstract

    A method is described for estimating the distribution of nerve-fiber conduction velocities in a nerve bundle. This method is based on a detailed general model of the nerve bundle compound action potential, which is characterized as a weighted sum of delayed single-fiber action potentials. The non-iterative estimation method is applied to two examples taken from existing literature, demonstrating the similarity of conduction velocity and fiber diameter distributions, sensitivity of the estimate to variations in important model parameters, and applicability to the differentiation of normal and abnormal nerve function.

    View details for Web of Science ID A1979GZ90900002

    View details for PubMedID 87308

  • CEREBRAL INFARCTION AND MIGRAINE - CLINICAL AND RADIOLOGIC CORRELATIONS NEUROLOGY DORFMAN, L. J., Marshall, W. H., Enzmann, D. R. 1979; 29 (3): 317-322

    Abstract

    Cerebral infarction was documented by arteriography and serial computed cranial tomography (CT) in four young adults (ages 16 to 32 years) with migraine. In one case, posterior cerebral artery occlusion produced a deep parietotemporal infarct. The other three cases all had frontotemporal infarcts (one hemorrhagic) in the territory of the middle cerebral artery, without major arterial occlusion. Two infarcts produced lasting neurologic deficits; one was associated with mild, transitory symptoms, and one was asymtomatic. Laboratory investigations in two cases revealed no hematologic or cardiovascular predisposition to cerebrovascular disease. Cerebral infarction, as revealed by CT, may be more prevalent in "complicated" migraine than is generally appreciated. Such lesions may or may not develop in chronologic and anatomic relationship to the headache, and may involve either large or small arteries. The prognosis for functional recovery, based on this limited sample, seems favorable.

    View details for Web of Science ID A1979GM19200007

    View details for PubMedID 571976

  • AGE-RELATED-CHANGES IN PERIPHERAL AND CENTRAL NERVE-CONDUCTION IN MAN NEUROLOGY DORFMAN, L. J., Bosley, T. M. 1979; 29 (1): 38-44

    Abstract

    Somatosensory evoked potential (SEP) latencies, motor and sensory nerve conduction velocities (CVs), and F-wave latenies were measured in 15 elderly normal subjects (mean age 74.1 years), and the results were used to derive indirect estimates of spinal cord CVs. These measurements were compared to those from 15 younger normal adults (mean age 31.6 years), and the nerve conduction characteristics of all 30 subjects were analyzed with respect to age. Peripheral motor and sensory CVs slowed progressively, and the onset latencies of F-waves and SEPs increased gradually with advancing age. Spinal cord CVs showed little change until approximately age 60, and declined sharply thereafter. In addition, the latencies of F-waves and SEPs were positively associated with height. Human clinical and experimental studies utilizing SEP and F-wave measurements must allow for morphologic differences between individuals, and for the systematic changes which accompany normal aging.

    View details for Web of Science ID A1979GE39100007

    View details for PubMedID 570675

  • PATTERN-REVERSAL VISUAL EVOKED-POTENTIALS IN LATE-ONSET PROGRESSIVE MULTIPLE-SCLEROSIS ELECTROMYOGRAPHY AND CLINICAL NEUROPHYSIOLOGY DORFMAN, L. J., Cummins, K. L. 1979; 19 (1-2): 89-94

    View details for Web of Science ID A1979GY70400010

    View details for PubMedID 499062

  • NERVE-FIBER CONDUCTION-VELOCITY DISTRIBUTIONS .2. ESTIMATION BASED ON 2 COMPOUND ACTION POTENTIALS ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY Cummins, K. L., DORFMAN, L. J., PERKEL, D. H. 1979; 46 (6): 647-658

    Abstract

    A method is presented for estimating nerve fiber conduction velocity distributions from non-invasive measurements of the compound action potential at two distinct locations separated by a known distance along the nerve bundle. This method is based on a model of the compound action potential as a weighted sum of delayed single-fiber action potentials, but does not require explicit knowledge of the single-fiber action potential wave shapes in order to yield a unique estimate of the conduction velocity distribution. Illustrative examples are presented from normal and diseases nerves. This method appears to have clinical applications in the electrophysiological assessment of peripheral nerve function.

    View details for Web of Science ID A1979GZ90900003

    View details for PubMedID 87309

  • JUVENILE NEUROAXONAL DYSTROPHY - CLINICAL, ELECTROPHYSIOLOGICAL, AND NEUROPATHOLOGICAL FEATURES ANNALS OF NEUROLOGY DORFMAN, L. J., Pedley, T. A., Tharp, B. R., Scheithauer, B. W. 1978; 3 (5): 419-428

    Abstract

    We describe 2 brothers with progressive myoclonus epilepsy that began in the second decade and was associated with cerebellar ataxia and intellectual deterioration. Electroencephalographic and cerebral evoked potential studies showed findings associated with myoclonus epilepsy. Neuropathological examination of 1 of the brothers, who died at age 23 years, revealed widespread changes of neuroaxonal dystrophy without pigment deposition in the basal ganglia. We propose the term juvenile neuroaxonal dystrophy (JNAD) to distinguish this condition on clinical grounds from infantile neuroaxonal dystrophy on the one hand, and on clinical and pathological grounds from Hallervorden-Spatz disease on the other hand. JNAD, while exceedinly rare, must be considered in the differential diagnosis of the progressive myoclonus epilepsies.

    View details for Web of Science ID A1978EZ59600010

    View details for PubMedID 103487

  • ELECTROPHYSIOLOGICAL LOCALIZATION OF CENTRAL SOMATOSENSORY LESIONS IN PATIENTS WITH MULTIPLE-SCLEROSIS ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY DORFMAN, L. J., Bosley, T. M., Cummins, K. L. 1978; 44 (6): 742-753

    Abstract

    Somatosensory evoked potentials (SEPs) and selected indices of peripheral nerve function were compared in 30 multiple sclerosis (MS) patients and 15 normal controls. A high incidence of delayed SEP onset was observed in the MS patients, correlating with sensory loss--particularly of joint position and vibration sense. Using a method for deriving an indirect estimate of spinal cord conduction velocity, the longitudinal level of the sensory disturbance could in many cases be localized either to the spinal or to the supraspinal segment (or both) of the somatosensory pathway. Abnormally low spinal conduction velocity correlated with clinical judgements of spinal cord malfunction, but abnormalities were encountered also in some cases with no clinical evidence of myelopathy. Electrophysiological studies can contribute to the assessment of patients with suspected MS by demonstrating conduction abnormalities in specific segments of the somatosensory pathway.

    View details for Web of Science ID A1978FK20700008

    View details for PubMedID 78803

  • EARLY PHASE IN LEBER HEREDITARY OPTIC ATROPHY ARCHIVES OF OPHTHALMOLOGY Nikoskelainen, E., SOGG, R. L., Rosenthal, A. R., Friberg, T. R., DORFMAN, L. J. 1977; 95 (6): 969-978

    Abstract

    Clinical, ophthalmoscopic, perimetric, and color vision tests and visual evoked responses were recorded in symptomatic and asymptomatic eyes in five members of a family with Leber hereditary optic atrophy. The presymptomatic eyes showed abnormalities in the retinal nerve fiber layer. Optic nerve dysfunction was found before central vision failed. The appearance of degenerating retinal nerve fibers, particularly in the papillomacular bundle, was documented photographically in the weeks after the onset of visual symptoms. Treatment with prednisone and hydroxocobalamin did not reverse or halt serious impairment of vision.

    View details for Web of Science ID A1977DK37200001

    View details for PubMedID 869755

  • VISUAL EVOKED-POTENTIALS IN LEBERS HEREDITARY OPTIC NEUROPATHY ANNALS OF NEUROLOGY DORFMAN, L. J., Nikoskelainen, E., Rosenthal, A. R., SOGG, R. L. 1977; 1 (6): 565-568

    View details for Web of Science ID A1977DJ98400008

    View details for PubMedID 883769

  • INDIRECT ESTIMATION OF SPINAL-CORD CONDUCTION-VELOCITY IN MAN ELECTROENCEPHALOGRAPHY AND CLINICAL NEUROPHYSIOLOGY DORFMAN, L. J. 1977; 42 (1): 26-34

    Abstract

    A method is described for deriving an indirect estimate of the velocity of impulse propagation in the spinal cord of intact man. The estimate is computed from measurements of motor and sensory nerve conduction velocity in the limbs, F-wave latencies, and the latencies of somatosensory evoked potentials. The mean estimated spinal cord conduction velocicy in normal subjects was found to be 55.1 m/sec, with a standard deviation of 9.9. This method appears to have potential application in the electrophysiological evaluation of patients with myelopathic disorders.

    View details for Web of Science ID A1977CR97700003

    View details for PubMedID 64347

  • ENCEPHALOMYELONEURITIS IN ABSENCE OF CANCER NEUROLOGY Langston, J. W., DORFMAN, L. J., Forno, L. S. 1975; 25 (7): 633-637

    Abstract

    An elderly man presented with signs and symptoms indicating a rapidly progressive central and peripheral nervous system disease, which led to death within 3 months. The pathologic picture was that of a "paraneoplastic" encephalomyelitis and neuritis, but no cancer could be found. Supratentorial predilection for the limbic structures correlated well with an observed limbic dementia. Arguments favoring a direct toxic or metabolic effect of cancer as a cause for this syndrome was less convincing in view of this report.

    View details for Web of Science ID A1975AJ21100007

    View details for PubMedID 1171394

  • CYTOMEGALOVIRUS ENCEPHALITIS IN ADULTS NEUROLOGY DORFMAN, L. J. 1973; 23 (2): 136-144

    View details for Web of Science ID A1973O666800005

    View details for PubMedID 4347063

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