ABSTRACTS OF POSTER AND PLATFORM PRESENTATIONS: 37th Annual Meeting American Association of Electrodiagnostic Medicine Chicago, Illinois, September 7-8, 1990
ASCENDING NERVE ACTION POTENTIALS IN ACQUIRED DEMYELINATING NEUROPATHY R.W. Gilliatt, D.M., C.A. Luciano, M.D., and R.A. Conwit, M.D. (National Institutes of Health, Bethesda, Maryland) In a small group of patients with acquired demyelinating neuropathy (chronic inflammatory demyelinating polyneuropathy [CIDP], paraproteinemic neuropathy) and with reduced motor conduction velocity (MCV) in the forearm, ascending nerve action potentials (NAPS) were recorded following median or ulnar nerve stimulation at the wrist, using a single active recording electrode over the nerve trunk just above the elbow, and a remote electrode over the deltoid insertion. This made it possible to measure maximal velocity in sensory fibers when digital sensory action potentials (SAPS)were absent or difficult to obtain. From the rise-time of the NAP it was also possible to estimate the degree of dispersion of the afferent volley. In 12 affected median and ulnar nerves, NAP velocity ranged from 43 to 62 mis (mean, 49 mis) whereas the MCV over the same segment ranged from 11 to 43 m/s (mean, 30 mis). Because of this difference in velocity, antidromic impulses in motor fibers did not usually contribute to the rising (negative-going) phase on the NAP. In some of the affected nerves NAP rise-times were markedly prolonged (range, 1.1-2.9 ms; mean, 2.1 ms) compared with age-matched controls (range, 0.7- 1.3 ms; mean, 1.0 ms), indicating that temporal dispersion of impulses in sensory fibers was increased, in spite of the relative preservation of velocity in the fastest-conducting fibers. ELECTROPHYSIOLOGIC SIMILARITIES AND DIFFERENCES BETWEEN ACUTE AND CHRONIC INFLAMMATORY DEMYELINATING NEUROPATHY G. Zuniga, M.D., D.P. Cros, M.D., J. Fang, M.S., A. Ropper, M.D., and B.T. Shahani, M.D. (Massachusetts General Hospital, Boston, Massachusetts) We compared electrophysiologic findings in 35 patients with inflammatory demyelinating neuropathy, acute variant (AIDP), and in 35 patients with the chronic variant (CIDP). Particular attention was given to un-
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equivocal documentation of demyelination and its location along the different segments of peripheral motor fibers. A total of 187 and 197 motor nerves (mean, 5.3 and 5.6 nerves per patient) were studied in AIDP and CIDP, respectively. Proximal conduction impairment (isolated F response abnormalities) was noted in 19% and 28% of nerves (P < .05), whereas conduction block in the intermediate segment was found in 19% and 29% of nerves (P < .02), respectively. Conduction slowing in the demyelinating range was seen in 6% of nerves in AIDP and in 26% of nerves in CIDP (P < .001), corresponding to slowing in 20% and 67% of patients, respectively ( P < .001). These findings support the notion of more widespread demyelinating lesions along the different segments of the motor fibers in CIDP than in AIDP. Conduction slowing, which is uncommon after recovery from AIDP, suggests remyelination of long segments of nerve previously demyelinated.
ELECTROPHYSIOLOGIC STUDIES IN PATIENTS WITH CHRONIC INFLAMMATORY DEMYELINATING POLYNEUROPATHY TREATED WITH INTRAVENOUS IMMUNE GLOBULIN J.E. Teasley, M.D., G.J.G. Parry, M.B., A.J. Sumner, M.D., C. Garcia, M.D., R.I. Malamut, M.D., and S.A. Erlemeier, M.D. (Louisiana State University School of Medicine, New Orleans, Louisiana) Nine patients with chronic inflammatory demyelinating polyneuropathy (CIDP) are presented who were treated with high-dose intravenous immune globulin (IVIG) (400 mglkglday for 3 days). Seven were treated because of failure or intolerance of previous treatment, including prednisone, cytoxan and plasma exchange, or because of the high risk of standard treatment. Two patients were treated with WIG as primary treatment. All patients reported subjective improvement in their sensory and motor symptoms. Eight patients had objective improvement in their strength. Electrophysiologic studies in 5 patients showed improvement, all of whom had objective improvement in their physical examination. The electrophysiologic improvements included decreased conduction block, decrease in latency or appearance of previously absent F waves and decrease in
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distal motor latency. There was no increase in distal compound muscle action potential amplitude or conduction velocity. These results indicate that high-dose IVIG is a useful addition to the armamentarium for treatment of CIDP as documented by the objective improvement in function and in the nerve conduction studies. Improved strength is probably related to reversal of conduction block, predominantly at the level of the ventral root. IVIG appears to hold promise as a primary modality in treatment of patients with CIDP but needs to be investigated in a more systematic manner.
CHRONIC DEMYELINATNG NEUROPATHY WITHOUT DEMYELINATION ON EMG T.R. Jacques, M.D., K.H. Levin, M.D., H. Mitsumoto, M.D., and A.J. Wilbourn, M.D. (Cleveland Clinic Foundation, Cleveland, Ohio) Six patients were followed and treated for chronic inflammatory demyelinating polyradiculoneuropathy, with disease duration ranging from 10 to 54 months. All 6 patients had an elevated cerebrospinal fluid (CSF) protein level with normal cell count and sural nerve biopsy evidence of segmental demyelination in the absence of significant axon loss. No patient had an EMG that was diagnostic of a demyelinating peripheral neuropathy. Of the 6 , 3 patients demonstrated EMG pictures of acute and chronic, predominantly motor axon loss in a polyradiculopathy pattern, one of whom showed no sensory abnormalities. The other 3 patients had the EMG presentation of acute and chronic, predominantly motor axon loss in a polyradicular pattern, but with mild suggestive features of superimposed demyelination. Five patients were treated with immunosuppressant therapy and/or plasmapheresis, with observation periods ranging from 5 to 30 months; 3 patients showed significant improvement in function, and 2 showed stabilization of their disease process. These patients demonstrate that unusual nondemyelinating EMG patterns can be seen with treatable demyelinating neuropathies.
MISDIAGNOSIS OF ACUTE ARSENICAL NEUROPATHY J.A. Difini, M.D., J.F. Santos, M.D., B. Barton, M.D., and D.R. Ayyar, M.D. (University of Miami and Miami V.A. Medical Center, Miami, Florida) Four patients were admitted to our Medical Center with peripheral neuropathy associated with a gastrointestinal illness. All of them had progressive limb weakness and dysesthesia. Examination revealed bilateral symmetric distal weakness, areflexia, and distal vibratory and joint position sense impairment. All 4 had anemia and 3 had pancytopenia. A diagnosis of Guillain-Barre syndrome had been made on the basis of slowed motor conduction velocities, abnormal F responses, conduction block with proximal stimulation and increased cerebrospinal fluid (CSF) protein without pleocytosis. The dysesthesia and anemia prompted toxicologic studies, which revealed
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high arsenic levels in the urine and hair. Penicillamine therapy resulted in gradual improvement of 2 out of 3 patients. One patient refused treatment. Arsenical neuropathy is typically characterized by axonal degeneration, but electrophysiologic features of demyelinative neuropathy may lead to misdiagnosis. Dysesthesia, anemia and continuing gastrointestinal symptoms should alert one to arsenical neuropathy, even in the presence of electrophysiologic features of demyelinative neuropathy, increased CSF protein without pleocytosis, and a diagnosis of Guillain-Barre syndrome. This is important because effectiveness of chelation therapy depends upon its early administration.
EMG IN NEURoPATHY D. M.D*, and J-J. Jr., M.D* (New England Medical Center, Boston, Massachusetts) Antiganglioside antibodies, especially anti-GM antibodies, have been associated with diseases of motor neurons and peripheral nerve. We have carried out EMG studies on 2 patients who presented with progressive wasting and weakness of the upper extremities associated with fasciculations and a generalized loss of tendon reflexes. One patient had accompanying numbness of the upper extremities. Anti-GM, antibody titers were elevated in both patients (1112600; 1/3292). Nerve conduction studies demonstrated reduced compound muscle action potentials (CMAPs) in wasted muscles. In several nerves, proximal stimulation resulted in dispersion of the motor responses and a reduction in amplitude without frank conduction block. Distal latencies were prolonged and motor conductions were slowed along multiple nerve segments, although not in the demyelinating range. Distal F wave latencies were delayed and dispersed even in nerves not demonstrating other conduction abnormalities, suggesting proximal root pathology. In one case (without sensory symptoms), sensory responses were reduced in amplitude although latencies were normal. Concentric needle EMG studies showed widespread chronic and active denervative changes. These abnormalities of nerve conduction studies and EMG predominantly involved the upper extremities. These findings are not typical of amyotrophic lateral sclerosis; their presence should alert the physician to the possibility of an underlying antiganglioside disorder. ELECTRODIAGNOSTIC RESULTS IN DIFFERENT STAGES OF HUMAN IMMUNODEFICIENCY VIRUS INFECTION R.K. Olney, M.D., Y.T. So, M.D., and H. Hollander, M.D. (University of California, San Francisco, California) Distal symmetric polyneuropathy (DSPN) develops in 35%-50% of acquired immune deficiency syndrome (AIDS) patients. T o clarify the relationship between human immunodeficiency virus (HIV) and DSPN, we are following 34 asymptomatic HIV seropositive men under
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the age of 50 years. None have conditions causing polyneuropathy or an abnormal neurologic examination. Nerve conduction (peroneal motor and sural), F wave and H reflex results were obtained with standard techniques and compared with control values and previously published results on AIDS patients.' Results on each asymptomatic patient were within normal tolerance limits. Significant group differences were found only for sural conduction velocity (CV), with the mean for asymptomatic patients being 45.1 m/s and for control subjects, 53.7 m/s (P < .001). Furthermore, mean sural CV was significantly greater in asymptomatic patients than in AIDS patients without (42.8 m/s) and with (39.9 m/s) DSPN. Mean sural amplitude, however, was significantly lower only in the AIDS patients with DSPN (2.7 pV), being 16-17 pV in the other 3 groups. Although DSPN was not identified in the asymptomatic group, sural CV was decreased suggesting an early subclinical effect of HIV on sural nerve. Whether decreased sural velocity reliably precedes decreased sural amplitude in DSPN will be examined in our longterm, prospective study of asymptomatic seropositive men. 1. So YT, Holtzman DM, Abrams DI, Olney RK: Peripheral neuropathy associated with acquired immunodeficiency syndrome (prevalence and clinical features from a population-based survey). Arch Neurol 1988; 45 :945-948. THE SPECTRUM OF ELECTRODIAGNOSTIC ABNORMALITIES IN PATIENTS WITH HUMAN IMMUNODEFICIENCY VIRUS INFECTION Y.T. So, MD., J.W. Engstrom, M.D., and R.K. Olney, M.D. (University of California, San Francisco, California) Over the past 3 years, electrophysiologic studies have diagnosed neuromuscular disorders in 51 of 81 patients referred with human immunodeficiency virus (HIV) infection in various stages. These disorders included 24 cases of distal symmetric polyneuropathy (DSPN), 3 of demyelinating polyneuropathy, 9 of lumbosacral polyradiculopathy, 14 of focal neuropathy, and 5 of myopathy. In DSPN, length-dependent sensorimotor axonal loss was reflected in low-amplitude or unrecordable sural (more than peroneal motor) responses, with only mildly reduced velocities. In demyelinating polyneuropathy, motor conduction studies showed multifocal slowing and abnormal F waves in 313 and conduction block in 213 patients. Patients with lumbrosacral polyradiculopathy had normal sural responses (7/9), low motor amplitudes (4/9), abnormal F waves (9/9), and fibrillations (7/8) and neurogenic recruitment (818) in multiple myotomes. In patients with focal neuropathy, after excluding commonly known causes, 7 had no identifiable risk factor aside from HIV infection, 3 had unilateral brachial plexopathy, 4 had one or more mononeuropathies outside common entrapment sites (peroneal, 3; median, 1; femoral, 1; long-thoracic, 1). EMG in myopathy revealed fibrillations (5/5), small and short-dura-
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tion motor unit potentials (5/5) and early recruitment (4/5); 415 patients were on zidovudine (AZT). Thus, a wide spectrum of electrodiagnostic abnormalities is seen in patients with HIV infection. CLINICAL AND ELECTROPHYSIOLOGIC FINDINGS IN FABRY'S DISEASE J.M. Ravits, M.D., F. Buchthal, M.D., and N. Barton, M.D. (National Institute of Neurological Disorders and Stroke, Bethesda, Maryland) Eleven male patients, 15-53 years of age with Fabry's disease, were studied. Nine patients complained of burning pain in the feet and the legs, often precipitated by heat or fever; 2 patients (brothers) were asymptomatic. Angiokeratomata were present in 10 patients. The consistent sensory abnormality was impairment of temperature perception in the feet in all but the 2 asymptomatic brothers. Sensory nerve conduction studies with near-nerve electrodes on the sural nerve showed normal maximum conduction velocity in all but 1 patient in whom the velocity was 22% slowed. The amplitudes of the sensory potentials were normal. The minimum conduction velocity was 40% slowed (9 m/s) in 5 of 9 patients. Motor nerve conduction studies with surface electrodes showed normal maximal conduction velocity in all but 1 of 7 patients (3 of 19 nerves), the same patient who had slowed conduction along the sural nerve. Electromyography of anterior tibia1 muscles in 7 patients showed an increased incidence of polyphasic potentials. In addition, the patient with abnormalities in nerve conduction had evidence of motor unit loss. Various autonomic studies (sinus arrhythmia, Valsalva ratio, and skin sympathetic response) were essentially normal. Near-nerve recording, especially of slow components, and quantitative EMG are the most sensitive electrophysiologic techniques for detecting polyneuropathy in Fabry's disease. COMPRESSION MONONEUROPATHIES IN A CHRONICALLY DISABLED POPULATION R.A. Werner, M.D., W. Waring 111, M.D., and F. Maynard, M.D. (University of Michigan Medical Center, Ann Arbor, Michigan) A prospective, cross-sectional study of 62 postpolio survivors was conducted to determine if their dependence upon the upper extremities increased the risk of curnulative trauma disorders such as compression mononeuropathies at the wrist. All subjects underwent thorough electrodiagnostic evaluations of both hands which included: median and ulnar sensory (standard and midpalmar) and motor evoked responses, radial sensory responses, ulnar motor conduction to the first dorsal interosseous (hand) and ulnar motor conduction across the elbow. A questionnaire was used to determine usage of assistive devices and activity level. Electrodiagnostic criteria for median mononeuropathy at the wrist was met in 58% (n = 34) with a clinically significant carpal
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tunnel syndrome of 26% (n = 16). The prevalence of an ulnar mononeuropathy was 38% (n = 23). Ulnar mononeuropathies at the wrist were associated with use of cane(s), but this did not hold true for median nerve injuries. Age was related to prevalence of median mononeuropathies, with the highest prevalence in the fifth and sixth decades. This relationship was not found with ulnar nerve lesions. Gender was not found to be associated with the prevalence of either median or ulnar lesions. These findings confirm a high prevalence of compression mononeuropathies in a chronically disabled population. RADIAL NERVE INVOLVEMENT IN PERIPHERAL NEUROPATHY D.X. Cifu, M.D., and S. Saleem, M.D. (V.A. Hospital, Houston, Texas) Early versus late involvement of the radial nerve in peripheral neuropathy has not been well examined. Recent reports, advocating a comparison of radial and median nerve sensory latencies (medial-radial latency difference [MRLD]) as a screen for mild carpal tunnel syndrome (CTS), have necessitated a better understanding of the degree of radial nerve involvement in peripheral neuropathy. Sensory superficial radial nerve latencies and amplitudes of 20 consecutive individuals seen with electrodiagnostic evidence (median, ulnar and sural nerve involvement) of peripheral neuropathy were obtained using standard techniques and compared to corresponding values of the median, ulnar and sural nerves. Statistically significant differences (P < .01) were noted between the latencies of the radial sensory (mean, 3.4 ms) and median sensory (mean, 4.4 ms) or all sensory nerves. Additionally, the MRLD (mean, 1.0) was significantly prolonged, without corroborating evidence of CTS. This investigation reveals that sensory radial nerve involvement in peripheral neuropathy occurs late (i.e., when evidence of motor peripheral neuropathy is present) rather than early (i.e., when only sensory peripheral neuropathy is present). This data suggests that, while the MRLD may serve as a sensitive screening method, a more extensive evaluation for mild peripheral neuropathy is always indicated. DIAGNOSTIC YIELD OF NERVE AND MUSCLE BIOPSY IN SUSPECTED VASCULITIS T.D. Thomas, M.D., S.J. Oh, M.D., J.L. Joy, M.D., and R.L. Pearlman, M.D. (University of Alabama at Birmingham, Birmingham, Alabama) Vasculitis is at times a very difficult diagnosis to secure with any degree of confidence. Different investigators have recommended nerve or muscle biopsy individually or in combination to confirm the diagnosis. We have reviewed all pathologic data on 54 patients who underwent both nerve and muscle biopsy for suspected vasculitis between 1974 and 1990. Biopsy material was classified as either negative, active, healed, or probable vasculitis. There were 31 men and 23 women with an
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average age of 63 years. Pathologic evidence of vasculitis was found in nerve biopsies in 46%: active (13%), healed (24%), and probable (9%). Vasculitis was found in 12 (22%) muscle biopsies. T h e sural nerve, however, also demonstrated the abnormality. In 13 patients, only the nerve biopsy was diagnostic. Only 3 of 14 (21.4%) biopsies were positive from outside hospitals versus 22 of 40 (55%) from our institution ( P < .01). All nerve biopsies performed at our institution were directed by electrodiagnostic studies compared to arbitrary site selection at community hospitals. We conclude that, compared to muscle biopsy, nerve biopsy is a more sensitive procedure for detecting vasculitis. Additionally, the diagnostic yield is increased when sural nerve biopsy is directed by electrodiagnostic testing. IRREGULARLY FIRING FIBRILLATIONS INDICATE RECENT ONSET LESION A.J. Wilbourn, M.D. (Cleveland Clinic, Cleveland, Ohio) Since the inception of clinical EMG, fibrillation potentials have played a major role in detecting abnormalities of the motor unit. They are recognized by their size, configuration and firing pattern, the latter usually being “metronomically” regular. We have studied 22 persons in whom irregularly firing fibrillation potentials (IFFPs) were seen in one or more muscles. Their etiology included: motor neuron disease, radiculopathies, diabetic amyotrophy, plexopathies, mononeuropathies, demyelinating polyradiculoneuropathies, and necrotizing myopathies. In 18 patients, the duration of the disorder could be determined: 5-6 months in 1, and