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Clinical electrophysiological characterization of the acquired neuromyotonia phenotype of autoimmune peripheral nerve hyperexcitability
Author(s) -
Maddison Paul,
Mills Kerry R.,
NewsomDavis John
Publication year - 2006
Publication title -
muscle and nerve
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.025
H-Index - 145
eISSN - 1097-4598
pISSN - 0148-639X
DOI - 10.1002/mus.20536
Subject(s) - neuromyotonia , motor unit , transcranial magnetic stimulation , neuroscience , medicine , neurophysiology , myasthenia gravis , peripheral , neuromuscular transmission , abnormality , peripheral nervous system , electromyography , neurology , electrophysiology , psychology , central nervous system , anesthesia , stimulation , immunology , psychiatry , antibody
Acquired autoimmune neuromyotonia is regarded as part of the spectrum of peripheral nerve hyperexcitability disorders. We aimed to use clinical neurophysiological measurements to study the extent, distribution, and characteristics of spontaneous motor unit potentials in 11 patients with acquired neuromyotonia. Investigations revealed that most spontaneous discharges recorded were motor unit, or partial motor unit potentials of normal size. Bursts of motor unit potentials arose more commonly from distal portions of the peripheral nerve and had abnormal absolute and relative refractory periods. Spontaneous discharges in some patients occurred in semirhythmic bursts in certain muscles. No patient had neurophysiological abnormalities detectable in first‐order neurons of the central nervous system when using transcranial magnetic stimulation to estimate the threshold for corticomotor excitation and determine central motor conduction time. Only patients with coexistent myasthenia gravis had neurophysiologically detectable defects in neuromuscular transmission. The pathogenic region of abnormality in peripheral nerve hyperexcitability disorders therefore seems to lie within the terminal branches of peripheral motor nerves. Muscle Nerve, 2006