Cauda Equina Syndrome Caused by a Sacral Insufficiency Fracture in the Lower Part of Zones 2 and 3: A Case Report

Abstract

Sacral insufficiency fractures (SIFs) often cause referred low back pain, and are rarely accompanied by cauda equina syndrome (CES). We report a case of CES caused by SIF in the lower part of zones 2 and 3, which is not a typical location. A postmenopausal woman often sat on a chair for long periods, and pain in the coccyx and perianal area occurred. After 4 years, during which time the pain worsened and she developed urinary and fecal incontinence, magnetic resonance imaging showed a SIF involving the S3-S5 vertebrae. Prolonged latency of the bulbocavernosus reflex was confirmed through an electrodiagnostic study, and detrusor underactivity was confirmed through a urodynamic study, leading to a CES diagnosis. Unlike typical cases of osteoporotic SIF, the fracture occurred at an atypical location. We believe that long periods of sitting caused a different weight-bearing pattern of the sacrum from that found in typical cases.