Related Experiment Video
Updated: Aug 25, 2026

Utility of Dissociated Intrinsic Hand Muscle Atrophy in the Diagnosis of Amyotrophic Lateral Sclerosis
Published on: March 4, 2014
[Hereditary myasthenic syndromes with late onset. Value of electrophysiological tests]
1Service d'Electromyographie, Hôpital Neurologique et Université Claude Bernard, Lyon.
Abstract:
A myasthenic syndrome was diagnosed in 3 female patients aged 37, 47 and 56 years. The symptoms were first noticed in childhood, and at 16 and 25 years. Respectively weakness and atrophy of finger extensor muscles were present in all patients. In 2 of them scapular and cervical muscles were involved. Weakness was markedly increased by cold in every patient. Similar symptoms were noted in first degree relatives in all cases. Single nerve stimulus elicited a repetitive compound muscle action potential in hand muscles. Repetitive nerve stimulation induced a myasthenic decrement in finger extensor muscles. SFEMG studies demonstrated increased jitter with frequent blockings. Genetic, clinical and electrodiagnostic data were consistent with the hypothesis of the so-called "Slow-Channel" myasthenic syndrome. As 2 of these patients were considered to have "unknown myopathy" the use of careful nerve stimulation tests is advocated in such cases.
Related Concept Videos
Chemical Synapses
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Myasthenia Gravis: Overview and Treatment
These antibodies interfere with the function of the nicotinic receptors in three ways: by binding to the receptor and disrupting acetylcholine binding; by causing cross-linking of receptors which leads...
Myasthenia Gravis: Diagnostic Tests
The edrophonium test is a diagnostic tool for myasthenia gravis. It involves...
Chemical Synapses
Because chemical synapses depend on the release of neurotransmitter molecules from synaptic vesicles to pass on their signal, there is an approximately one millisecond delay between when the axon potential reaches the presynaptic terminal and when the neurotransmitter leads to opening of postsynaptic ion channels. Additionally, this signaling is...
Myasthenia Gravis ll: Pathophysiology
Alterations in Muscle Tone lll

