Frequency and specific surgical management of far lateral lumbar disc herniations.

A) Frequency of Far Lateral Lumbar Disc Herniation: The analysis of pre-operative computer-assisted tomograms and myelograms in a series of 694 operated lumbar disc herniations showed that a far lateral disc prolapse occured in 7% of the cases. Within the group of those far laterally herniated discs 3% of the herniations were predominantly located in the intervertebral foramen, whereas 4% of the protruded discs were mainly situated extraforaminally compressing the spinal nerve in its paravertebral course. B) Surgical Management of Extraforaminal Far Lateral Lumbar Disc Herniation: By March 1988 40 patients had been operated on for an extraforaminal disc protrusion making use of an external microsurgical exposure (in two cases by a transmuscular approach and in 38 cases via an enlarged midline approach). A medium-term follow-up of these 40 patients revealed a substantial clinical relief of pain in 34 cases (85%). Based on these gratifying results we regard the external exposure of the extraforaminally protruded disc as the treatment of choice.