Motor Branch Biopsy of the Pronator Teres Muscle in a Patient with Painful Forearm Neuropathy

Histological evaluation of a peripheral nerve is often the final diagnostic work-up for a neuropathy of unknown origin, and a distal sensory nerve is usually biopsied. Here, we report the case of a female patient with painful unilateral neuropathy in the upper arm. According to the histological evaluation of the pronator teres motor branch, vasculitis seemed to be the most probable cause of the condition, and steroid therapy improved the patients’ symptoms. A biopsy of the motor branch of the pronator teres muscle nerve may be considered a valuable diagnostic option in selected cases with neuropathy affecting the upper limb, when performed in cooperation with neurologists and orthopedic surgeons.