Diagnosis and treatment of extreme lateral lumbar disc herniation.

Extreme lateral lumbar disc herniation is located in the foramen and compresses the exiting root producing symptoms attributed to the upper nerve root of the involved disc and vertebral level. The diagnosis is best established by using magnetic resonance imaging which visualizes the foramen in an axial and sagittal plane. Surgical treatment may be varied, but a posterior midline approach with drilling of the pars interarticularis will easily expose the nerve root and the herniated disc in the foramen. Results are usually excellent, with resolution of radicular pain.