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Motor neuron firing range, axonal conduction velocity, and muscle fiber histochemistry in neuromuscular diseases
Author(s) -
Borg J.,
Grimby Lennart,
Hannerz Jan
Publication year - 1979
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.880020603
Subject(s) - nerve conduction velocity , motor neuron , neuroscience , muscle fibre , motor unit , anatomy , medicine , chemistry , biology , spinal cord , skeletal muscle
The voluntary discharge properties and axonal conduction velocity of single motor units were studied in patients with neuromuscular diseases with retained differentiation of the muscle fibers into type 1 and type 2, and in patients with late‐onset hereditary distal myopathy in which muscle fibers have only intermediate histochemical properties. In the patients with muscle fiber differentiation, the findings were similar to those in normal subjects; that is, there was a continuum between motor units which fired tonically at low rates and had a low axonal conduction velocity, and motor units which fired phasically at high rates and had a high axonal conduction velocity. In the patients without muscle fiber differentiation, all motor units had intermediate firing properties and a low axonal conduction velocity. It is suggested that in chronic pathologic states, the differentiation of the muscle fiber histochemistry remains only as long as the differentiation of the motor neurons remains.