Foot Drop Caused by Single-Level Disc Protrusion Between T10 and L1

Study Design. Retrospective investigation of surgical treatment of 25 patients with foot drop from single-level disc protrusion in the region of T10 to L1. Objective. To describe cases of foot drop from single-level disc protrusion in the region of T10 to L1 and surgical outcomes. Summary of Background Data. Three cases of foot drop from T12-L1 disc protrusion are reported in the literature. Little is known, however, about foot drop resulting from single-level disc protrusion between T10 and L1 or its surgical outcomes. Methods. Between January 1995 and October 2010, a total of 25 patients (mean age: 44 yr; range, 21-68 yr) presented to our department with single-level disc protrusion between T10 and L1 (6 at T10-T11, 7 at T11-T12, and 12 at T12-L1) with associated foot drop and without cervical or lumbar spinal stenosis or other neurological disease. The average follow-up period was 46.5 months. We treated all cases surgically with circumferential decompression with fixation. We assessed neurological status, tibialis anterior muscle strength, magnitude of local kyphosis, and cross-sectional area at the level of compression of the dural sac preoperatively and at the final follow-up. Results. Preoperatively, all 25 patients exhibited both foot drop resulting from a lower motor neuron lesion and pathological reflexes resulting from an upper motor neuron lesion. Postoperatively, the mean calculated muscle strength recovery rate was 95%. Mean Japanese Orthopaedic Association score increased from 5.92 +/- 1.22 points preoperatively to 9.56 +/- 0.92 points at the final follow-up. Magnetic resonance imaging indicated that the cross-sectional area increased from 36.3 +/- 7.3 mm(2) preoperatively to 133.1 +/- 6.1 mm(2) postoperatively. Conclusion. Foot drop can be caused by single-level disc protrusion between T10 and L1 and is usually associated with an upper motor neuron lesion. Pathological reflexes resulting from disc protrusion occurring between T10 and L1 differ depending on the level of the protrusion. Circumferential decompression with fixation may be an effective treatment option for this syndrome.