Dorsal root entry zone lesioning for pain after brachial plexus avulsion: Results with special emphasis on differential effects on the paroxysmal versus the continuous components. A prospective study in a 29-patient consecutive series

Abstract

Pain after brachial plexus avulsion (BPA) is generally characterized by 2 main different components: paroxysmal (electrical shooting-like) pain, and continuous (burning) pain. Dorsal root entry zone (DREZ) lesioning, namely, the microsurgical DREZotomy (MDT) used in our practice, has proved to be a worthwhile neurosurgical treatment for this indication. However, according to previous studies, the method does not seem to demonstrate as good effectiveness in patients in whom the continuous background of pain was predominant as in patients with the paroxysmal component predominating. To obtain more insight into this problem, a prospective study on an eventual differential effect of the MDT procedure on the 2 components was undertaken. The presented series included 29 consecutive patients affected with pain after BPA who underwent an operation over the 10 last years. Pain intensity was evaluated using a visual analogue scale (VAS). At last evaluation of the 26 patients followed for 12 to 122 months (60 months on average) after MDT, 76.9% had a good or excellent global pain relief after surgery, ie, pain control with or without additional nonopioid medications, respectively. According to the component types of pain, 84.6% of patients had good or excellent control of the paroxysmal pain, and 73.1% of the continuous pain. Kaplan-Meier prediction of lasting global pain control at 120 months of follow-up was calculated at 41.1%. Comparison of the 2 corresponding Kaplan-Meier curves at long term, namely, pain control in 76.2% for the paroxysmal component and in 43.1% for the continuous component, showed a statistically significant difference (P=.038). Hypotheses for this relative differential effect are discussed.

Thalamic deep brain stimulation for neuropathic pain after amputation or brachial plexus avulsion

“…1,13,58 Motor cortex stimulation (MCS) has also been undertaken with equivocal results influencing paroxysms more than continuous pain, 2,33 and spinal cord stimulation (SCS) has been reported with limited success. 15,64 No trials comparing neuromodulation treatments for BPA have been reported.…”

Correlation of preoperative MRI with the long-term outcomes of dorsal root entry zone lesioning for brachial plexus avulsion pain

“…1,9,23,27 None of these papers explicitly report the median follow-up time, and 2 papers report outcomes at the mean follow-up times. It is thus difficult to interpret these studies.…”

“…1,27 Marked rotation or lateral deviation of the spinal cord was noted in 34.5% 1 to 49% 27 of patients due to arachnoid adhesions. A significant proportion (22.5%-36.4%) were also noted to have abnormal tissue near the dorsolateral sulcus on microscopic examination, which consisted of focal gliosis or microcystic cavitation within the DREZ or dorsal horn.…”

“…1,2,5,9,24,25,27,29 Though not as frequently performed as a few decades ago, DREZotomy remains a potent surgical therapy for the management of pain from BPA and other spinal cord injuries. 1,26 DREZotomy involves the surgical destruction of the erratically firing second-order neurons of the ascending nociceptive pathway, and clinical outcomes following DREZotomy have been correlated with the abolition of spontaneous and evoked hyperactivity in the dorsal horn. 7,11,24 The procedure was first described by Sindou in 1972 using an arachnoid knife to incise the spinal cord at the DREZ before enlarging the lesion using thermal coagulation.…”

“…For example, the presence of pseudomeningoceles, while considered a classic indirect sign of root avulsion, is not a sensitive indicator of the injury level, with up to 50% of partially or totally avulsed roots showing no observable meningeal alterations on MRI. 1 As a result, determining the levels to treat is a clinical decision made by noting the motor and sensory deficits and directly examining the spinal cord intraoperatively; segments with frankly absent, partially avulsed, grayish, or atrophic-appearing rootlets are treated. 27 Focal gliosis and microcysts of the DREZ may also be seen at the time of surgery.…”