Surgical Strategy for Lumbar Spine Dumbbell Tumors Based on a New Classification

BACKGROUND: Current spinal dumbbell tumor classifi- cations are excessively focused on dumbbell tumors of the cervical spine and corresponding surgical strategies, neglecting lumbar dumbbell tumors, and appropriate stra- tegies for such lesions. OBJECTIVES: We aimed to establish a classification of lumbar dumbbell tumors (LDTs) based on diagnostic im- aging and lesion location to enable the selection of optimal surgical strategies. METHODS: We retrospectively analyzed 39 patients who had LDTs evaluated at a single institution. Herein, we propose categories defined by tumor position in the hori zontal and longitudinal tumor length in the coronal direction. RESULTS: Thirty-nine patients with LDTs were surgically treated. The pathology consisted of schwannoma, neurofi- broma, hemangioma, and a cyst in 33, 3, 2, and 1 cases, respectively. Based on the new classification, type IA, type IB, type IC, type ID, type IIA, type IIB, and type IIB/M were diagnosed in 6, 4, 3, 1, 20, 2, and 3 cases, respectively. Thirteen, 23, 1, and 2 patients underwent surgery using posterior, paraspinal, oblique retroperitoneal, and com- bined approaches, respectively. Gross total resection was achieved in all patients. The complications included ce- rebrospinal fluid leakage in 2 cases and infection in 1. Thirty-six patients showed clinical improvement, 2 showed no change in clinical status, and 1 was lost to follow-up because the patient's contact information changed. CONCLUSIONS: This classification of LDTs by their po- sition in the coronal and axial planes is a simple and practical basis for selecting a surgical approach.