Bilateral gluteal dyskinesia: discussion of a rare movement disorder.

Involuntary movements of gluteal muscles have rarely been reported.This 46-year-old female with pelvic endometriosis developed involuntary rhythmic movements in the left gluteus maximus, which within a year became bilateral. The movements gradually increased in intensity and interfered with ambulation. Electromyography, at rest, demonstrated almost continuous periodic gluteal discharges, with left-sided discharges seeming to lead to those on the right. OnabotulinumtoxinA injections into the gluteal muscles improved the movements.A rare and previously unreported form of gluteal involuntary movements with periodic electromyographic discharges is described. The cause is uncertain. The differential diagnosis of this unusual movement disorder is discussed, with the most likely diagnosis being myoclonus.