Acute cauda equina syndrome secondary to lumbar disc herniation mimicking pure conus medullaris syndrome--case report.

A 49-year-old male presented with a rare case of acute cauda equina syndrome secondary to a sequestrated lumbar disc mimicking pure conus medullaris syndrome. He consulted the emergency room of Otsu Municipal Hospital because saddle anesthesia and complete urinary retention which had started 2 days before admission. Additionally, he complained of constipation and impotence. Abnormality of the deep tendon reflexes, sciatica, and leg weakness were not organized. Emergent myelography and subsequent computed tomography revealed a sequestrated disc in the sacrum compressing the lower cauda equina, but not the conus medullaris. Emergent surgical decompression was performed about 60 hours after the onset. The patient almost fully recovered from sphincter dysfunction, impotence, and saddle anesthesia 3 months after the operation. When a syndrome like conus medullaris compression is encountered, the lower cauda equina should be examined as well as the conus level. Such cases require urgent diagnosis and treatment.