Thick filament degeneration in a case of acute quadriplegia.

Absence of thick filaments from the A bands in tissue giving apparently normal histochemical reactions for myosin ATPase, was seen in a case of acute onset muscle weakness progressing rapidly to quadriplegia with cerebral involvement. There was also widespread degeneration of interstitial structures and much phagocytosis. The dissociation of structure and function of the thick filaments suggests that a selective injury occurred within the myosin molecule. The etiology of the condition although clinically suggestive of a polyneuropathy remains pathologically uncertain. Toxic, immunological or viral causation may be responsible.