Abstract
Objectives We aimed to assess the diagnostic utility of a muscle biopsy in a general neurology setting, and to identify strategies to improve patient selection.
Methods The clinical records and histology reports of adult patients who underwent a muscle biopsy at Wellington Hospital, New Zealand, between February 2004 and December 2020, were retrospectively examined. Their clinical, laboratory, and electromyography findings, histology results, and pre- and post-biopsy diagnoses were recorded. Based on the findings, strategies for optimising patient selection have been proposed.
Results Eighty-four patients underwent a muscle biopsy during this period, with a mean age of 57.9 years; 47.6% female. A specific diagnosis was reached in 65 (77%): immune-mediated myositis (21), inclusion body myositis (21), hereditary myopathy (13), vasculitis (5), rhabdomyolysis (2), hypothyroid myopathy (1), connective tissue disease (1), and denervation (1). Of these, the pre-biopsy diagnosis was confirmed in 51 (78%). Age, duration of symptoms, creatine kinase level, and the presence of myositis-specific antibodies, were useful in discriminating between the three most common post-biopsy diagnoses. Absence of clinical muscle weakness was predictive of a non-specific or normal biopsy result.
Conclusion A specific diagnosis was achieved in 77% of patients who underwent a muscle biopsy, with confirmation of the pre-biopsy diagnosis in the majority. Clinical and laboratory features were, in some cases, more discriminatory than a biopsy. We propose a clinical algorithm to refine patient selection for muscle biopsy.
