Diagnostic features of sciatica without lumbar nerve root compression

STUDY DESIGN: Retrospective case series review of patients showing sciatica without radiographic evidence of nerve root compression. OBJECTIVE: To elucidate clinical features of sciatica caused by extralumbar spinal lesions. SUMMARY OF BACKGROUND DATA: Sciatica caused by extralumbar spinal lesions has been reported sporadically. Given the paucity of case series studies, however, the pathology and clinical features of such sciatica remain not fully understood. METHODS: Sixty-one patients who presented with persistent sciatica were examined with lumbar magnetic resonance (MR) imaging. Of these, the records of patients showing no detectable nerve root compression in MR images were reviewed with respect to demographics, neurologic status, further diagnostic procedures, treatments, and treatment outcomes. RESULTS: Of 61 patients, 10 (16.4%) showed sciatica and a lack of nerve root compression in the lumbar MR imaging. In demographics, there was female sex dominance (9 patients) and right side preference (9 patients). Eight patients exhibited sensory disturbance beyond a single dermatome. Piriformis syndrome was diagnosed in 3 patients and 5 patients were considered to have sacral plexus pathologies associated with gynecologic conditions such as ectopic endometriosis, ovarian cyst, and pregnancy. A review of the literature also supported the right side preference in sciatica associated with gynecologic conditions. CONCLUSIONS: Piriformis syndrome and gynecologic conditions account for most cases of extralumbar spinal sciatica. Female sex, right side involvement, and overlapping sensory disturbance are suggestive of extralumbar spinal sciatica associated with gynecologic conditions.