[A case of far-out syndrome: case report and review of the literature].

Far-out syndrome (FOS) is a rare disease in which the L5 nerve root is compressed by a transverse process, the sacral ala, and a bony spur at the extraforaminal zone. We report the case of patient with FOS due to a bulging disc and review the literature. This 34-year-old male experienced severe left leg pain and slight motor weakness of the left extensor digitorum. Radiographic studies revealed no abnormality in the spinal canal. The intervertebral disk bulged to the left. Because of fat it was difficult to discern the left L5 nerve root from the sacral ala in the extraforaminal zone. His symptoms failed to respond to conservative treatment and he underwent decompression of the L5 nerve root without fusion. During the operation, the left L5 nerve root was exposed by drilling the sacral ala via the left paraspinal approach. The sacral ala was removed along with the left L5 nerve root to obtain sufficient pulsation and movement of the left L5 nerve root. Neither the intervertebral joint nor the intervertebral disk was removed. The patient's symptoms disappeared immediately after surgery. Due to anatomical factors, the L5 nerve root is easily compressed and the presence of this syndrome should be considered in a differential diagnosis. Careful and appropriate decompression without fusion yielded an excellent outcome.