MICROSURGICAL EXCISION OF LATERAL LUMBAR DISC HERNIATION THROUGH AN INTERLAMINAR APPROACH

We made a prospective study of 43 consecutive patients treated for int raforaminal (34) or extraforaminal (9) herniations of a lumbar disc by excision through an interlaminar approach, using an operating microsc ope, The intraforaminal herniations were contained or extruded in 52% and sequestrated in 47%; for extraforaminal herniation the proportions were 66% and 33%, respectively, There was additional posterolateral p rotrusion or spinal stenosis at the level of the lateral herniation in seven and four cases, respectively, The patients were reviewed at thr ee months and two years after surgery, Radiographs showed three grades of facetectomy: grade I, removal of 50% or less, grade II, excision o f 51% to 75%, and grade III, subtotal or total facetectomy, For intraf oraminal herniations the results were excellent or good in 88% of pati ents when reviewed at three months and in 91% at two years, For extraf oraminal herniations, there was an excellent or good outcome in 89% of patients in the short term and in ail in the long term, The facetecto my had been grade I in 14 and grade II in 25; it had been grade III in four, but only one had had total facetectomy, No patient had develope d vertebral hypermobility as a result of the operation, An intralamina r approach using an operating microscope can provide adequate access t o a lateral protrusion, It has the advantage of allowing the treatment of posterolateral protrusion or posterior annular bulge and of spinal stenosis at the same level.