Electrophysiological Findings in Radiation-induced Lumbosacral Plexopathy

Original Article

J Korean Assoc EMG Electrodiagn Med 2011;13(2):111-117.
Published online December 1, 2011.

Received: 9 August 2011 • Revised: 10 October 2011 • Accepted: 7 November 2011

Abstract

Radiation-induced lumbosacral plexopathy is a rare complication of pelvic irradiation. There are few reports of detailed clinical and electrophysiological studies. In this retrospective study, we identified all patients with a diagnosis of radiation-induced lumbosacral plexopathy encountered at Seoul National University Hospital between 1979 and April, 2010. We were able to find five patients, whose characteristic clinical features can be summarized as follows: 1) One of the five patients had rectal cancer and the others had cervical cancer. 2) The time from radiotherapy to the development of symptoms ranged from 3 to 15 years. 3) The initial presentation was lower extremity weakness in three patients and tingling sense in two patients. 4) Three of the five patients presented at least one severe complication such as radiation-induced enteritis, proctitis or cystitis. Nerve conduction studies showed frequent abnormal findings in the superficial peroneal sensory nerve, sural sensory nerve, peroneal motor nerve and tibial motor nerve. Gastrocnemius(100%), peroneus longus(100%), tensor fascia latae(100%) and tibialis anterior(80%) showed the highest rate of abnormalities in needle electromyography. Four of the five patients showed myokymic discharges in at least one of the muscles including gastrocnemius, peroneus longus, tensor fascia latae, tibialis anterior and gluteus maximus. These results suggest certain nerves and muscles should be selected for the diagnosis of radiation-induced lumbosacral plexopathy by electrophysiologic studies.

Key Words: Radiotherapy, Lumbosacral plexopathy, Radiation plexopathy