Comparative outcomes of microsurgical dorsal root entry zone lesioning (DREZotomy) for intractable neuropathic pain in spinal cord and cauda equina injuries

Abstract

Treatment of neuropathic pain in patients with spinal cord injury (SCI) and cauda equina injury (CEI) remains challenging. Dorsal root entry zone lesioning (DREZL) or DREZotomy is a viable surgical option for refractory cases. This study aimed to compare DREZL surgical outcomes between patients with SCI and those with CEI and to identify predictors of postoperative pain relief. We retrospectively analyzed 12 patients (6 with SCI and 6 with CEI) with intractable neuropathic pain who underwent DREZL. The data collected were demographic characteristics, pain distribution, and outcomes assessed by numeric pain rating scores. Variables and percentages of pain improvement at 1 year and long-term were statistically compared between the SCI and CEI groups. The demographic characteristics and percentage of patients who experienced pain improvement at 1 year postoperatively did not differ between the groups. Compared with the SCI group, the CEI group presented significantly better long-term pain reduction (p = 0.020) and favorable operative outcomes (p = 0.015). Patients with border zone pain had significantly better long-term pain relief and outcomes than did those with diffuse pain (p = 0.008 and p = 0.010, respectively). Recurrent pain after DREZL occurred in the SCI group but not in the CEI group. DREZL provided superior pain relief in patients with CEI. The presence of border zone pain predicted favorable outcomes. CEI patients or SCI patients with border zone pain are good surgical candidates for DREZL, whereas SCI patients with below-injury diffuse pain are poor candidates.

Keywords: Cauda equina injury; DREZotomy; Dorsal root entry zone lesioning; Neuropathic pain; Spinal cord injury; Surgical outcome.

Fig. 1

Intraoperative procedures of DREZL for pain relief in a patient with neuropathic pain of the non-functional lower extremities. (A) exposure of the posterolateral surface of the spinal cord (arrow) and DREZ (arrowheads) after posterior reflection of the dorsal spinal nerve roots (asterisks); (B) coagulation of small arteries covering the DREZ (arrowhead); (C) incision along the DREZ (arrowheads) using an ophthalmic microsurgical blade; (D) microsurgical coagulation of the DREZ (arrowhead) using fine-tip bipolar coagulation forceps with adequate depth and correct trajectory; (E) exposure of the dorsolateral sulcus (arrowheads) of the spinal cord after DREZL; (F) complete lesioning along the DREZ (arrowheads) of the targeted spinal cord segments. DREZ, dorsal root entry zone; DREZL, dorsal root entry zone lesioning

Fig. 2

Intraoperative findings and DREZL procedure in a SCI patient with neuropathic pain of the lower limbs. The patient had diffuse pain below the injury level. The targeted spinal cord segments for the lesioning were inferior to the level of extensive spinal cord damage. Arachnoid adhesions and gliotic formation adjacent to the injury site might obscure intraoperative identification of the DREZ. (A) the area of SCI (arrow) and intact targeted spinal cord segments for DREZL located below level of the injury (arrowhead); (B) excision of gliotic tissues and adhesions around the injured spinal cord; (C) the thick arachnoid mater covering the intact spinal cord (arrowhead) and dorsal spinal nerve roots (asterisks) below level of the injury; (D) dissection of the arachnoid membranes away from the spinal cord and nerve roots; (E) posterior mobilization of the dorsal spinal nerve roots (asterisks) to expose the posterolateral surface of the spinal cord (arrowhead); (F) identification of the DREZ (arrowheads) after reflection of the dorsal spinal nerve roots (asterisks); (G) incision of the DREZ using an ophthalmic microsurgical blade; (H) microsurgical coagulation of the DREZ with appropriate depth and precise angle; (I) after complete operative procedure, the image showing reposition of the dorsal spinal nerve roots (asterisks), area of SCI (arrow) in more rostral position, and lesioned spinal cord segments (dotted shape) in more caudal position. DREZ, dorsal root entry zone; DREZL, dorsal root entry zone lesioning; SCI, spinal cord injury

Fig. 3

Intraoperative findings and DREZL procedure in a CEI patient with neuropathic pain of the lower limbs. The injury occurred at the level of the cauda equina while the targeted spinal cord segments for DREZL located more rostral to the injury level were structurally normal. The intact spinal cord segments facilitate an effective lesioning procedure. (A) exposure of the intact spinal cord (arrowhead) and proximal spinal nerve roots (asterisks) near the spinal cord; (B) reflection of the dorsal spinal nerve root to reveal the DREZ (arrowheads); (C) incision along the DREZ using an ophthalmic microsurgical blade; (D) microsurgical coagulation of the DREZ using fine-tip bipolar coagulation forceps; (E) exposure of the dorsolateral sulcus (arrowheads) of the targeted spinal cord segments after the lesioning; (F) reposition of the dorsal spinal nerve roots following complete DREZL. CEI, cauda equina injury; DREZ, dorsal root entry zone; DREZL, dorsal root entry zone lesioning