Minimally Invasive Lateral Retroperitoneal Approach for Resection of Extraforaminal Lumbar Schwannomas: Results After 1-Year Follow-Up.

Objective: Extradural spinal nerve sheath tumors with foraminal involvement are rare, and the gold standard for surgical resection is not established yet. Traditionally, lumbar intra-extraforaminal schwannomas have been resected through a posterior midline or paraspinal open approach. The lateral transpsoas approach represents a suitable, minimally invasive approach which can provide direct access to the extraforaminal and lumbar plexus region avoiding bone removal, hence the necessity of lumbar fusion. The aim of this study is to share our experience of extraforaminal lumbar schwannomas approached through a minimally invasive lateral transpsoas technique with intraoperative neurophysiological monitoring.

Methods: This is a single-center retrospective case series study. Seven adult patients who underwent extraforaminal lumbar schwannoma removal through a lateral retroperitoneal approach were enrolled. A detailed description of the surgical technique is reported. The outcome measures included mean surgical duration, mean blood loss, postoperative mobilization, day of discharge, complication, postoperative symptoms, and extent of removal. All patients had a minimum follow-up of 1 year.

Results: The average age was 51 years. Surgery lasted 225 minutes on average, with minimal blood loss. One patient had a cerebrospinal fluid leak, which was successfully repaired. Most patients were mobilized the day after surgery and 6 were discharged within 2-4 days. At a 12-month follow-up, 6 patients showed symptom improvement and magnetic resonance imagings confirmed complete tumor resection in all cases.

Conclusions: Retroperitoneal transpsoas approach represents a safe tool in the neurosurgeon's armamentarium, particularly suitable for this subset of tumors representing a short and direct way to approach them. Surgeon confidence of working inside the psoas and close to the lumbar plexus is increased using continuous electromyography monitoring. At the end, the retroperitoneal transpsoas approach for extraforaminal lumbar schwannoma can provide minimal soft tissue damage, better pain control, decreased blood loss, and short hospitalization.