Diagnostic Biopsy of the Pronator Teres and a Motor Branch of the Median Nerve: Indications and Technique

PurposeBiopsy of muscle tissue and motor nerve is helpful in the neurological evaluation of patients who present with upper limb and/or diffuse motor weakness. The procedure is indicated to supplement clinical, serological, and imaging diagnostic work-up of myopathic and neuropathic disorders. We describe a surgical technique and clinical series of biopsy of the pronator teres muscle and a motor branch of the median nerve.MethodsWe performed a retrospective review of 20 patients who underwent biopsy of the pronator teres and a motor branch of the median nerve as part of a clinical, serological, and radiographic evaluation for weakness of the upper extremity. All of the biopsies were performed by a single surgeon. The surgical technique is described. Follow-up visits with both the surgeon and the neurologist were reviewed to evaluate preoperative and postoperative neurological function to identify any changes in nerve or muscle function and any postoperative complications.ResultsBiopsied tissue was sufficient for pathological diagnosis in all 20 patients. Diagnoses included multifocal motor neuropathy in 14 patients, amyotrophic lateral sclerosis in 3 patients (2 sporadic; 1 familial), inclusion body myositis (1 patient), inflammatory myopathy (1 patient), and chronic inflammatory demyelinating polyneuropathy (1 patient). At a mean follow-up of 11 weeks (range, 5–31 wk), there were 6 minor surgical complications, all of which were superficial hematomas that resolved with use of a compressive wrap.ConclusionsBiopsy of the pronator teres and a motor branch of the median nerve was safe and effective. The technique is particularly useful when considering the diagnosis of multifocal motor neuropathy affecting the upper extremity.Type of study/level of evidenceDiagnostic III.