Minimally invasive far lateral microendoscopic discectomy for extraforaminal disc herniation at the lumbosacral junction: cadaveric dissection and technical case report.

Background Context: Extraforaminal lumbar disc herniations (ELDHs) at the lumbosacral junction are an uncommon cause of L5 radiculopathy. The surgical anatomy of the extraforaminal space at L5-S1 is uniquely challenging for the various open surgical approaches that have been described for ELDHs in general. Reports specifically describing minimally invasive surgical approaches to lumbosacral ELDHs are lacking.

Purpose: To report the novel use of a far lateral microendoscopic (FLMED) approach to lumbosacral ELDH. To better define the unique anatomical features of extraforaminal approaches to the lumbosacral junction as they apply to minimal access techniques.

Study Design/setting: A cadaveric investigation and clinical case were performed at a single institution. A thorough review of the literature was conducted.

Patient Sample: A single patient with an extraforaminal disc herniation at the lumbosacral junction underwent evaluation and surgery.

Outcome Measures: The patient's self-reported pain levels were documented. Physiologic outcome was judged on pre- and postoperative motor and sensory examinations. Functional capacity was assessed by work status and ability to perform activities of daily living.

Methods: FLMED was performed in two fresh human cadavers at the lumbosacral junction. Qualitative assessments of the surgical anatomy were made, and intraoperative fluoroscopy and endoscopic photographs were obtained to document the findings. A patient with refractory pain and sensorimotor deficits from compression of the L5 nerve root by an ELDH underwent FLMED. The literature was carefully reviewed for the epidemiology of ELDHs at the lumbosacral junction and the surgical techniques used to treat them.

Results: The posterolateral surgical corridor to the lumbosacral disc was consistently constrained by the sacral ala and to a lesser extent the lateral facet and L5 transverse process. Resection of the superior ala exposed the exiting nerve root and provided ample access to the disc. In the clinical case, the patient enjoyed immediate pain relief, was discharged in 3 hours, and returned to full work and social activities. Follow-up neurological examination revealed no sensory or motor deficit.

Conclusions: FLMED offers a safe and efficacious approach to ELDHs at the lumbosacral junction by combining satisfactory visualization for adequate resection of the sacral ala with the benefits of reduced tissue injury and faster recovery times that accompany minimally invasive techniques.