Chapter 6 - Muscle and Nerve Pathology

Summary

For decades, muscle biopsy has been considered an essential part of the work-up of patients suspected of a neuromuscular disease, alongside the physical examination, laboratory testing, electromyography, muscle imaging, and molecular investigations.

However, muscle biopsy is usually not the first diagnostic test requested when the clinical phenotype of a myopathic patient is clear (‘Gestalt’) and the molecular diagnosis is straightforward. For example, for patients with a phenotype of facioscapulohumeral dystrophy, Duchenne muscular dystrophy, or myotonic dystrophy, genetic investigations are the primary requested diagnostic tests. Since next-generation sequencing (NGS) has entered the diagnostic arena, a muscle biopsy is no longer a first-tier examination if a hereditary neuromuscular disorder – be it a myopathy, neurogenic disorder, or congenital myasthenic syndrome – is considered. Likewise, in patients with subacute weakness, especially if accompanied by skin abnormalities, the introduction of new serological markers has made the position of the applicability of muscle biopsy questionable according to some clinicians.