Minimally invasive anterior contralateral approach for the treatment of cervical disc herniation.

BACKGROUND: During the practice of ipsilateral approach to the offending lesion in anterior simple discectomy, the authors realized that it achieves better surgical exposure of the opposite foraminal area. In addition, it was also realized that routine procedures for better visualization of the foraminal area, such as stripping longus colli muscles, further excising of the anterior longitudinal ligament, or using a spreader, which cause more invasive surgery during the standard anterior approach, are not necessary because the contralateral approach already achieves sufficient exposure of the target foraminal area.

OBJECTIVE: Evaluation of the results and effectiveness of this minimal invasive technique in patients with either soft or hard disc herniations.

METHODS: Between January 1994 and April 2002, 216 patients underwent anterior contralateral microdiscectomy without fusion for cervical disc herniation at 1 or 2 adjacent levels. Anterior contralateral microdiscectomy is a less invasive technique than standard anterior simple discectomy in which longus colli muscles are not stripped, and the lateral part of annulus fibrosis at the side of intervention and ventrolateral part of it at the opposite side are not removed. In addition, a mini Zenker handheld retractor is used for retraction of paravertebral soft tissues and a spreader is not used during the discectomy procedure. There were 182 patients diagnosed with radiculopathy and 34 patients with myelopathy. Assessments of the neurological status of patients with radiculopathy were done by physical examinations, and of those with myelopathy according to the modified Japanese Orthopaedic Association cervical spine functional assessment scale. These neurological assessments were repeated in the 18th month after surgery. In the follow-up period, the outcomes of surgery were also assessed for all patients in 4 categories, from failure to excellent.

RESULTS: Surgery outcomes generally have been good to excellent and none of the patients were made worse by the procedure. The outcomes were significantly better in the radiculopathy and soft disc herniation groups. Other positive outcome factors were short duration and sudden onset of symptoms, normal cervical curvature, and single-level disease. Follow-up radiological studies revealed fibrous healing with normal or slight loss of disc height in 199 (92.1%) patients and total obliteration of the involved disc space representing radiological fusion signs in 13 (6%) patients. The overall complications observed in this study were 2 spontaneous and 2 postinfection collapses of disc level, 1 excessive fibrosis of disc level, and 2 adjacent-level diseases.

CONCLUSION: Anterior contralateral microdiscectomy without fusion achieves better exposure for resection of the offending foraminal or far lateral lesions, ventral osteophytes, or a disc fragment under direct microscopic visualization. Collapse and instability of the involved disc level can also be avoided via this less invasive technique.