gms | German Medical Science

Objective: According to Wiltse et al. the lateral lumbar spinal canal can be divided into the subarticular (lateral recess), the foraminal (pedicle) and the extraforaminal (far lateral) zone. Some authors refer to the subarticular and foraminal region as the “hidden zone” due to ist difficult surgical exposure. Conventional approaches usually involve medial facet joint resection, thereby going along with an increased risk of postoperative instability. In order to minimize this long-time complication, we employed a translaminar cross-over approach for pathologies in the “hidden-zone”.

Method: We report about six patients with cranial disc herniations in the so called “hidden zone” that underwent sequestrectomy using a translaminar approach. NRS pain score, ODI score and standardized questionnaire concerning postoperative daily function (COMI) were used to evaluate clinical outcome after six weeks and three months. A high-speed drill was used to create a small (10 x 10 mm) angled fenestration in the exposed contralateral hemilamina, whereby the medial portion of it, just at the base of the spinous process, served as entry point. The working-channel-like fenestration at the contralateral side was pinpointed under fluoroscopic control to the ipsilateral “hidden zone”. The exiting nerve root was visualized microscopically and disc fragments were removed.

Results: A successful microsurgical approach from the contralateral side was achieved in all patients. The surgical procedure lasted 98 ± 25 min. Removal of the disc herniation could be documented by a postoperative lumbar CT-scan in all cases. At three month follow-up pain scores had improved significantly (e.g. NRS leg pain score preoperative: 8,1 ± 1,8; after three months: 2,6 ± 1,9). COMI score was reduced significantly from 7,7 ± 1,2 to 3.9 ± 1,3. The ODI improved from 63 ± 18 to 27 ± 14 during follow-up.

Conclusions: This series can be regarded as a proof of principle for a successful translaminar crossover approach to the “hidden-zone”. This technique allows preserving facet joint function on both sides. It therefore might reduce the risk of instability and accelerate rehabilitation. Technically, crossover recessotomy could be an option for cases with lateral recess stenosis as well. Apart from intraforaminal disc herniation or lateral recess stenosis, other indications could conceivably be nerve sheath tumors in the lateral recess and / or foraminal zone and patients with severe Baastrup's disease.