EP.118Triple trouble or normal aging?

Abstract

Some pathological features such as rods, polyglucosan bodies or COX-negative fibers that can be found in muscle and nerve biopsies are generally linked to specific disorders. The significance of such findings in elderly people is unknown. Here we present unexpected pathological findings in muscle and nerve biopsies of an 81-year-old man who suffered from lower-limb pain, paresthesia and deltoid atrophy, for which a polyneuropathy was suspected. The muscle biopsy showed fiber size variation and groups and atrophic fibers of both type 1 and type 2. The trichrome stain showed numerous fibers with subsarcolemmal accumulations of nemaline bodies (rods). Oxidative enzyme stains showed abundant cytochrome c oxidase (COX)-negative succinate dehydrogenase (SDH)-positive fibers and some targetoid fibers. Nerve biopsy showed reduction of myelinated and unmyelinated axons and 13 polyglucosan bodies. Rods, polyglucosan bodies and paracristalline inclusions were (also) identified by electronic microscopy. Nerve biopsy findings were consistent with an axonal polyneuropathy. However, muscle and nerve biopsy also show features of unexpected disorders without any clinical correlate. Rods can typically be identified in a subset of congenital myopathies, or in sporadic late onset nemaline myopathy (SLONM) and in HIV-associated nemaline myopathy. This patient did not have any clinical features or laboratory findings of nemaline myopathy or SLONM. Polyglucosan bodies are characteristics of polyglucosan body myopathy, a glycogenosis (GSD IV) due to decreased branching enzyme activity. The adult form of the disorder usually presents with progressive spastic paraparesis, neurogenic bladder, dementia and peripheral neuropathy. Apart from the polyneuropathy, our patient did not have any other characteristic features. The biopsy also showed features of mitochondrial dysfunction, which is a phenomenon known to increase with age, although its prevalence is unknown. We present a patient with mild polyneuropathy symptoms and prominent findings in nerve and muscle biopsies, which are held to be highly specific for certain diseases. Whether the pathological findings are responsible for the polyneuropathy and further symptoms are yet to come or whether they are 'just' the result of 'aging' is difficult to establish.