Objective: Standard surgical procedures for the treatment of far cranio-lateral or foraminally extruded lumbar disc herniations include interlaminar exposure with partial or complete resection of the upper hemilamina and sometimes partial removal of the facet joint and weakening of the pars interarticularis. We present our experiences with the translaminar approach to this entity of lumbar disc herniation using a tubular retractor system.
Methods: Fifteen patients with far cranio-laterally extruded disc herniations underwent neurosurgical intervention using a translaminar approach. The paraspinal muscles were spread with a dilatator after performing a 1.5 cm skin incision. A 16 mm METRx tubular retractor system (Medtronic Sofamor Danek, Memphis, TN) was directly placed on the upper lamina. The next steps were performed through this channel using the surgical microscope. A small ovoid fenestration (10x5 mm) was performed using a high speed drill and the disc prolapse was removed in a standard manner. Follow-ups were routinely carried out 3 weeks postoperatively and reassessment was subsequently carried out by telephone inquiry 10 to 44 months (median 23 months) after treatment. These results were rated according to the modified MacNab criteria.
Results: Five of the fifteen affected discs were at the level L3/4, eight at L4/5 and two at L5/S1. The average surgical time was 55 minutes. No complications occurred. In all patients sciatic pain disappeared immediately after the operation. One patient underwent fusion of the affected level one year later because of progression of a pre-existent pseudospondylolisthesis. Long-term follow-up demonstrated excellent results in six, good results in seven, a fair result in one and a poor result in one patient according to the modified MacNab criteria.
Conclusion: The translaminar approach in conjunction with a tubular retractor system seems to be an effective and safe alternative technique for treating the small entity of far cranio- laterally or foraminally extruded lumbar disc herniations. It combines the advantages of a blunt muscle-spreading approach that produces little damage to the soft tissues, and the avoidance of large bone removal that may jeopardize vertebral stability. Since this approach does not permit sufficient exploration of the intervertebral disc space of origin, it should be limited to patients without significant bulging of the disc itself.