Resection of a giant paravertebral retroperitoneal schwannoma via the weaver approach: a case report on technical refinements and surgical considerations.

Objective: This study aims to evaluate the surgical feasibility, technical refinements, and clinical outcomes of resecting a giant paravertebral retroperitoneal schwannoma using the Weaver intermuscular approach. It also emphasizes key anatomical considerations, surgical techniques, and potential pitfalls to guide spine and peripheral nerve surgeons in managing similarly complex lesions. Case description: A 51-year-old woman presented with a six-month history of progressive discomfort in the left lumbar region. Physical examination revealed no focal neurological deficits or other significant findings. Magnetic resonance imaging revealed a large left-sided paravertebral retroperitoneal mass measuring 90 × 108 × 122 mm, extending through the L3-L4 intervertebral foramen and compressing adjacent structures, including the abdominal aorta, kidney, and psoas muscle. Radiological findings suggested a neurogenic tumor. The tumor was completely resected using a posterior muscle-splitting Weaver approach. Key technical refinements included precise preoperative imaging-based trajectory planning, partial resection of the L3 and L4 transverse processes to expand the lateral working corridor, staged intracapsular debulking, meticulous extracapsular dissection, and preservation of retroperitoneal integrity. Conclusions: This case demonstrates that the Weaver intermuscular approach can be safely and effectively applied to giant paravertebral retroperitoneal schwannomas with foraminal extension. With appropriate patient selection and meticulous microsurgical technique, this posterior muscle-sparing approach offers a viable alternative to traditional anterior or combined approaches, minimizing surgical morbidity and preserving spinal stability.