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P12-9 Conduction block in acute motor axonal neuropathy
S174 from acute onset to chronic. Weakness was focal in 1, while localized to both hands in another patient. All other patients had widespread mainly asymmetric weakness of the upper and lower limbs. Sensory symptoms were mild or inconspicuous. Motor and sensory nerve conductions were performed, including MNC studies of the forearm and elbow-axilla segments of the median and ulnar nerves. The results were evaluated using our reference values. Results: Six patients exhibited undetectable or small mixed nerve action potential amplitudes, while sensory nerve conductions showed no or only minimal abnormalities. These patients demonstrated demyelinating motor nerve conduction abnormalities along with multifocal CB and responded favorably to steroids, with an unsatisfactory or absent response to IVIg. The remaining patient with chronic focal weakness and motor CB responsive to IVIg displayed no demyelinating motor nerve conduction velocity slowing. Conclusion: MNC studies predict the therapeutic response to corticosteroids in chronic demyelinating neuropathy patients with multifocal CB, in a group of cases which otherwise would be classified as multifocal motor neuropathy or pure motor variant of the chronic inflammatory demyelinating neuropathy. P12-9 Conduction block in acute motor axonal neuropathy N. Kokubun1 , M. Nishibayashi1 , T. Sada1 , K. Hirata1 , N. Yuki2 1 Departments of Neurology, Dokkyo Medical University, Japan, 2 Departments of Neurology and Clinical Research, Niigata National Hospital, National Hospital Organization, Niigata, Japan Objective: Autopsy studies demonstrate early nodal changes in acute e syndrome, motor axonal neuropathy (AMAN) pattern of Guillain Barr´ which may be able to produce conduction block (CB) in the motor nerves. Methods: Repeated motor nerve conduction studies were performed for 18 AMAN patients. Clinical and serological findings were compared between subgroups. Results: Twelve (67%) of the 18 patients had definite (n = 7) or probable (n = 5) CBs. At the intermediate nerve segment of median and ulnar nerves, definite CB was detected in one patient (6%) and probable CB in five (28%). Across elbow segment of the ulnar nerve, definite CB was shown in seven patients (39%) and probable CB in two (11%). Seven of the 12 patients had reversible CB (true CB) and six CB followed by axonal degeneration (pseudo CB): One of them showed both true and pseudo CBs. Clinical features and anti-ganglioside antibody profiles were similar between the patients with and without CB as well as those with and without reversible CB. Conclusion: AMAN patients often have CBs at the intermediate and common entrapment sites, and such patients show true CB, pseudo CB or both. These indicate that CB is a cardinal finding for understanding the AMAN pathophysiology. The coexistence of true and pseudo CBs in an individual reveals that both conditions are not distinct and form a continuous spectrum. Similar clinical and serological features between each subgroup support that true CB, pseudo CB and axonal degeneration without CB are continuous conditions. P12-10 Multiple measures of peripheral nerve excitability in vivo in a mouse model of demyelinating neuropathy D. Boerio-Gueguen1,2 , J.-P. Lefaucheur2,3 , A. Creange2,4 , E. Benoit1 CNRS, Institut de Neurobiologie Alfred Fessard, FRC2118, Gif sur Yvette, France, 2 EA 4391, CHU Henri Mondor, Faculte de Medecine de Creteil, Universite Paris XII, France, 3 Service de Physiologie, Explorations Fonctionnelles, CHU Henri Mondor, Creteil, France, 4 Service de Neurologie, CHU Henri Mondor, Creteil, France
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Objective: To characterize excitability changes in a mouse model of demyelinating neuropathy. Methods: Acquired demyelination was induced in 6 Swiss female mice at the age of 13 weeks, by injecting 100 ml of physiological solution containing 124 units of a protease of bovine pancreas in the perineural space of the caudal nerve, at the base of the tail. Excitability properties were assessed by stimulating the caudal motor nerve at the base of the tail and recording the compound muscle action potential (CMAP) using needle electrodes inserted into the tail muscle. A first evaluation was performed before the induction of demyelination and then repeated recordings were achieved over 40 days. A control group
Posters (age- and gender-matched) was injected with placebo and recorded according to the same schedule, to appraise the effects of substance injection and repeated recordings. Excitability measurements included stimulus-response, strength-duration and current-threshold relationships, threshold electrotonus and recovery cycle. Results: Two days after protease injection, mice displayed a reduced CMAP amplitude associated with an increased threshold, a reduced strength-duration time constant, smaller superexcitability and late subnormal period (p < 0.05). Furthermore, they also exhibited a fanning in of the electrotonus, i.e. smaller threshold changes in response to polarizing currents (p < 0.05). Gradual recovery was observed throughout 21 days until complete recovery after 29 days. Conversely, excitability properties of the control group remained fairly stable along the evaluation period. Conclusion: Acquired demyelination induced within 2 days transient axonal excitability changes in mice, in vivo, suggesting an impairment of membrane potential and/or ion channels function associated with myelin sheath alteration. Taking into account the results of clinical evaluation of patients showing demyelinating neuropathy, this mouse model is potentially of great interest to appraise the ability of therapeutics to counteract the observed changes and exacerbate their recovery. P12-11 Nerve conduction characteristics of infliximab induced demyelinating neuropathy K. Sekiguchi1 , F. Kanda1 , T. Toda1 , N. Kohara2 Department of Neurology, University of Kobe, Hyogo, Japan, 2 Kobe city general hospital, Kobe, Japan
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Objective: Investigate electrophysiological and clinical characteristics in tumor necrosis factor-alpha antagonist infliximab (Remicade) induced demyelinating neuropathy in two cases. Method: Examine standard nerve conduction study in two rheumatoid arthritis patients who occurred demyelinating neuropathy sixth months after initiation of infliximab treatment. Result: One patient revealed nerve conduction findings similar to multifocal motor neuropathy with multiple conduction blocks. Sensory nerve action potential amplitude also slightly decrease whereas no sensory symptoms. It resembles to findings of vasculitic neuropathy with pseudo-conduction block except dramatically clinical recovery by treatment and persistent conduction block. Another patient were fit for typical findings of chronic inflammatory demyelinating polyneuropathy such as prolonged motor distal latency, conduction slowing, and abnormal temporal dispersion of compound muscle action potentials. Each cases improving symptoms and conduction findings by IVIg treatment. Conclusion: Infliximab induced demyelinating neuropathy did not display uniform impairment pattern on nerve conduction study. Underlying predisposing vulnerability of demyelinating neuropathy might appear by infliximab suppression of tumor necrosis factor-alpha immune regulatory role. P12-12 Neonatal axonal neuropathy: a curious presentation of congenital hypomyelination L.M. Notghi1 , S. Wright1 , R. Quinlivan1 Birmingham Children’s Hospital, Birmingham, U.K.
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In our neonatal intensive care setting, hypotonia with ventilatory failure is a relatively common indication for electrodiagnosis. Where a neuromuscular cause of weakness is found, the most frequent diagnoses are spinal muscular atrophy, myasthenic syndromes and myopathy. Congenital neuropathies are much rarer, and of congenitial hypomyelination neuropathy 16 cases are reported in the literature. A female infant, second child of unrelated parents with no significant family history, was born at full term after a pregnancy complicated by first trimester maternal parvovirus and hydrops foetalis. Congenital heart defects and profound hypotonia were detected at birth but she was self-ventilating on air until day five, when respiratory acidosis and arrest required mechanical ventilation. Over the next four weeks she needed full ventilatory support, became increasingly weak and developed contractures around distal and proximal joints. Facial muscles were unaffected. Intravenous immunoglobulin was ineffective. Initial nerve conduction studies on day 10 showed very small motor responses with no temporal dispersion. Motor velocities were normal or moderately slowed. Sensory responses were very small or absent. Needle EMG showed,
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Objective: To characterize excitability changes in a mouse model of demyelinating neuropathy. Methods: Acquired demyelination was induced in 6 Swiss female mice at the age of 13 weeks, by injecting 100 ml of physiological solution containing 124 units of a protease of bovine pancreas in the perineural space of the caudal nerve, at the base of the tail. Excitability properties were assessed by stimulating the caudal motor nerve at the base of the tail and recording the compound muscle action potential (CMAP) using needle electrodes inserted into the tail muscle. A first evaluation was performed before the induction of demyelination and then repeated recordings were achieved over 40 days. A control group
Posters (age- and gender-matched) was injected with placebo and recorded according to the same schedule, to appraise the effects of substance injection and repeated recordings. Excitability measurements included stimulus-response, strength-duration and current-threshold relationships, threshold electrotonus and recovery cycle. Results: Two days after protease injection, mice displayed a reduced CMAP amplitude associated with an increased threshold, a reduced strength-duration time constant, smaller superexcitability and late subnormal period (p < 0.05). Furthermore, they also exhibited a fanning in of the electrotonus, i.e. smaller threshold changes in response to polarizing currents (p < 0.05). Gradual recovery was observed throughout 21 days until complete recovery after 29 days. Conversely, excitability properties of the control group remained fairly stable along the evaluation period. Conclusion: Acquired demyelination induced within 2 days transient axonal excitability changes in mice, in vivo, suggesting an impairment of membrane potential and/or ion channels function associated with myelin sheath alteration. Taking into account the results of clinical evaluation of patients showing demyelinating neuropathy, this mouse model is potentially of great interest to appraise the ability of therapeutics to counteract the observed changes and exacerbate their recovery. P12-11 Nerve conduction characteristics of infliximab induced demyelinating neuropathy K. Sekiguchi1 , F. Kanda1 , T. Toda1 , N. Kohara2 Department of Neurology, University of Kobe, Hyogo, Japan, 2 Kobe city general hospital, Kobe, Japan
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Objective: Investigate electrophysiological and clinical characteristics in tumor necrosis factor-alpha antagonist infliximab (Remicade) induced demyelinating neuropathy in two cases. Method: Examine standard nerve conduction study in two rheumatoid arthritis patients who occurred demyelinating neuropathy sixth months after initiation of infliximab treatment. Result: One patient revealed nerve conduction findings similar to multifocal motor neuropathy with multiple conduction blocks. Sensory nerve action potential amplitude also slightly decrease whereas no sensory symptoms. It resembles to findings of vasculitic neuropathy with pseudo-conduction block except dramatically clinical recovery by treatment and persistent conduction block. Another patient were fit for typical findings of chronic inflammatory demyelinating polyneuropathy such as prolonged motor distal latency, conduction slowing, and abnormal temporal dispersion of compound muscle action potentials. Each cases improving symptoms and conduction findings by IVIg treatment. Conclusion: Infliximab induced demyelinating neuropathy did not display uniform impairment pattern on nerve conduction study. Underlying predisposing vulnerability of demyelinating neuropathy might appear by infliximab suppression of tumor necrosis factor-alpha immune regulatory role. P12-12 Neonatal axonal neuropathy: a curious presentation of congenital hypomyelination L.M. Notghi1 , S. Wright1 , R. Quinlivan1 Birmingham Children’s Hospital, Birmingham, U.K.
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In our neonatal intensive care setting, hypotonia with ventilatory failure is a relatively common indication for electrodiagnosis. Where a neuromuscular cause of weakness is found, the most frequent diagnoses are spinal muscular atrophy, myasthenic syndromes and myopathy. Congenital neuropathies are much rarer, and of congenitial hypomyelination neuropathy 16 cases are reported in the literature. A female infant, second child of unrelated parents with no significant family history, was born at full term after a pregnancy complicated by first trimester maternal parvovirus and hydrops foetalis. Congenital heart defects and profound hypotonia were detected at birth but she was self-ventilating on air until day five, when respiratory acidosis and arrest required mechanical ventilation. Over the next four weeks she needed full ventilatory support, became increasingly weak and developed contractures around distal and proximal joints. Facial muscles were unaffected. Intravenous immunoglobulin was ineffective. Initial nerve conduction studies on day 10 showed very small motor responses with no temporal dispersion. Motor velocities were normal or moderately slowed. Sensory responses were very small or absent. Needle EMG showed,