Butterfly vertebra. A case report and a short review of the literature.

A butterfly vertebra is a rare congenital anomaly, encountered as isolated finding or as part of syndromic diseases. We report a case of a 40-year- old female presenting with low back pain and sciatica due to 'butterfly' dysplasia of the first sacral vertebra. This novel case includes posterolateral displacement of the completely separated hemivertebrae, causing left lateral recess stenosis and compression of S1 nerve root. Additionally, we conducted a short review of the literature. Few cases are reported in literature. Only one refers to a sacral vertebra. There is no previous case of a butterfly vertebra that accounts for narrowing of the lateral recess and associated radiculopathy.