Foraminal and extraforaminal lumbar disc herniations

Between August 1992 to November 1994, 7 cases of foraminal and 3 cases of extraforaminal lumbar disc herniation were diagnosed and operated on, which represented an incidence of 4.1% of all operated lumber disc herniations. Contrasted to the typical disc herniation, foraminal and extraforaminal disc herniations involved the upper nerve root mainly. The dominent symptoms and signs were severe anterior thigh and lower leg pain, positive femoral nerve strech test, impairment of knee jerk reflex and weakness of the quadriceps muscle. Sequestration and extrusion were the most common type of disc pathology. CT/MRI showed the protruded disc in and outside of the foramen clearly. It was thought to be ideal method for the precise diagnosis and guidance of surgery. However the variations of the nerve root or other diseases related to it should be identified. All of the 10 cases underwent surgical treatment with the approach by outer edge of pars interarticularis in 8. The result was encouraging with complete improvement in 8 cases, obvious improvement in 1 case, and partial improvement in another case. It was found that the approach had the advantage of good exposure and effect with the minimal destruction of pars interarticularis and facet joint which would not give rise to lumbar instability.