Progressive neurogenic muscle atrophy with fasciculation in mice treated with IDPN.

Spontaneous discharges recorded on the EMG appeared in experimental mice given repeated doses of IDPN according to a time schedule. Spontaneous discharges showing a polyphasic pattern and duration of over 10 ms were considered to be fasciculations. One group of mice, treated with IDPN for 4 weeks became active with an increase in muscle volume 2 months after initiation of experiment; spontaneous discharges were recorded in this group at 3-4 weeks after first IDPN injection and disappeared at 4 months. Histologically, neurogenic muscle atrophy, in terms of group atrophy of muscles, was seen in muscles of mice exhibiting spontaneous discharge patterns. Peripheral nerves showed marked atrophy with degeneration. Dissociation of neurofilaments and other organelles was observed. Axonal swellings, filled with numerous maloriented neurofilaments, were confirmed in the lumbar cord. IDPN given repeatedly to mice at a certain dose causes degeneration of the peripheral nerves and results in neurogenic muscle atrophy.