Electromyography and muscle biopsy in chronic isolated Myalgia: A prospective study

Chronic muscle pain affects approximately 10% of the general population. It is unknown whether electromyographic (EMG) examination or muscle biopsy is most useful in this situation.

In a 7-year, single-center prospective study we investigated the EMG and muscle pathology characteristics of patients with: (1) diffuse muscle pain lasting >1 year; (2) normal clinical examination; (3) normal extensive blood tests; and (4) no evidence of a coexisting disorder.

One hundred eighty consecutive patients were enrolled. In 178 patients (99%), EMG studies and muscle biopsies were normal. In 2 patients (1%), EMG studies demonstrated myotonia, and muscle biopsy showed mild myopathic features; 1 patient had myotonic dystrophy type 2, and the other had SCN4A-related muscle channelopathy.

In this prospective study, EMG was an excellent screening test for diagnosing muscle disease in clinically normal patients with chronic diffuse muscle pain, and muscle biopsy was not useful. Muscle Nerve 54: 321-324, 2016.