Muscle fibre types in denervation

Abstract

In a large proportion of chronic neuropathies and motor neurone disease, in biopsies taken from clinically little affected muscles, the fibre type grouping is not conspicuous, so that this pattern should not be considered as a hallmark of the morphologic diagnosis of denervation. In this respect, the increased terminal innervation ratio remains a much more reliable parameter. The high proportion of type III or intermediate fibres occurring preferentially in cases without obvious type grouping must be emphasized, with regard to the hypothesis that these fibres represent a transient stage of reinnervation through collateral branching of subterminal axons. The pattern of type I grouping with numeric and sometimes volumetric reduction of type II fibres occurring in obviously neuropathic conditions leads to a reappraisal of the so called type II atrophy observed in disuse atrophy and in some myopathies. A neural influence in these conditions should only be accepted when there are characteristic changes in the terminal motor innervation pattern. (Journal received: 22 Oct. 1974)SCOPUS: NotDefined.jinfo:eu-repo/semantics/publishe