Dorsal root entry zone ablation for lower limb pain after thoracolumbar spine fracture

Abstract

Objective To evaluate the efficacy and safety of dorsal root entry zone (DREZ) ablation surgery in the treatment of lower limb pain after thoracolumbar fracture, and to analyze the underlying mechanism of lower limb pain. Methods From October 2011 to December 2016, a total of 20 patients with lower limb pain after thoracolumbar fracture were treated with DREZ ablation in the spinal cord segment corresponding to the dermatome of the pain territory at Department of Functional Neurosurgery, Xuanwu Hospital, Capital Medical University. The relationship between the segments of the spinal cord injury, sensory level, and area of pain was analyzed retrospectively. The efficacy (overall VAS score improvement more than 50%, no more analgesics needed) and safety of the operation were evaluated according to the postoperative pain relief and complications. Results The segments of spine injuries were T12-L3, and the pain territory was distributed at T11-S2, which lied 2-6 segments higher than that of the injured spinal cord segment. Spinal cord and nerve root were severely injured at the fractured vertebra level. The corresponding spinal cord segments of the pain territory dermatome were moderately atrophied and in 12 cases the corresponding nerve roots were avulsed from the spinal cord. Eighteen patients was pain free right after the operation, 2 cases with pain relieve rate less than 50%. 1 case developed pain recurrence after 3 months. The effective rate on time interval with immediate, 3months and 1 year after operation was 18/20, 17/20, 17/20 respectively. Seven patients had developed transient stabbing pain within the upper boundary of the ablated segment. Two patients who underwent unilateral DREZ lesion developed irritant pain in the contralateral lower extremity area after the operation. Conclusions Chronic neuropathic pain of the lower limb due to thoracolumbar fracture seems more likely to be caused by nerve root injury instead of spinal cord injury. DREZ ablation is safe and effective for those patterns of pain. Key words: Spinal fractures; Spinal cord injuries; Neurosurgical procedures; Neuropathic pain; Dorsal root entry zone