Dorsal root entry zone (DREZ) localization using direct spinal cord stimulation can improve results of the DREZ thermocoagulation procedure for intractable pain relief

Abstract

The dorsal root entry zone (DREZ) thermocoagulation for intractable pain after brachial plexus avulsion was performed in 21 patients. Good results in pain relief (relief of more than 75% of preoperative pain) were achieved in 62% of patients, whereby fair results (relief of 25-75% of preoperative pain) in 38% of patients. There was no patient with poor result (relief of less than 25% of preoperative pain). Complication rate was 14%. The whole patient population was subdivided into two groups (Group 1 and Group 2). Direct spinal cord bipolar stimulation and registration with the goal to localize DREZ was performed in the Group 2 consisting of 12 patients (n=12). The point on the spinal cord surface where no response after stimulus of low intensity was obtained was the site (the posterolateral sulcus) we identified as the most suitable point for the placement of radiofrequency thermocoagulation electrode. Comparing with the Group 1 consisting of nine patients (n=9), where the localization of DREZ by evoked potentials was not performed, significantly better effect of pain relief was recorded (P<0.05, odds ratio 10). There was no statistically significant difference (P>0.7) in complication rate in Group 1 and Group 2. Described electrophysiological technique is very helpful in identifying of DREZ and, in combination with microsurgical technique, can create DREZ thermocoagulation more effective.

Treatment of Postherpetic Neuralgia Using DREZotomy Guided by Spinal Cord Stimulation

“…Secondly, a loss of both large- and small-diameter fibers generates spontaneous activity in deafferented central neurons, producing constant pain in a region of profound sensory deficits without allodynia. The DREZotomy may destroy the sprouting in the dorsal horn to relieve the PHN, while the SCS may reestablish the impaired balance between excitatory and inhibitory mechanisms in sensitized dorsal horn neurons [4,11,18]. …”

“…An alternative is dorsal root entry zone lesion (DREZotomy); yet, its cure rate is also not very high, ranging from 50 to 66% [8,9,10]. Besides, DREZotomy involves the risk of gait disorders and risks connected with anesthesia, ranging from 0 to 60% [11,12]. A misplaced thermocoagulation lesion may cause unwanted neurological deficits because of the close proximity of the lateral corticospinal tract and dorsal column to the site of DREZ lesions.…”

“…A misplaced thermocoagulation lesion may cause unwanted neurological deficits because of the close proximity of the lateral corticospinal tract and dorsal column to the site of DREZ lesions. Therefore, it seems that an accurate localization is necessary to improve the therapeutic effect and reduce complications [11]. Several techniques of spinal cord-evoked response registration after peripheral nerve stimulation have been described in the literature [11,13,14].…”

“…Therefore, it seems that an accurate localization is necessary to improve the therapeutic effect and reduce complications [11]. Several techniques of spinal cord-evoked response registration after peripheral nerve stimulation have been described in the literature [11,13,14]. However, these electrophysiological techniques could not locate the exact segment because the recordings were relatively low in amplitude and the components were difficult to distinguish.…”

Surgical Treatment of Brachial Plexus Injury

“…Sites where the stimulation electrode failed to evoke a response are considered as a dorsal root entry zone and thermocoagulation lesion is made at that site. The stimulating technique is repeated along the axis of the spinal cord at 1 cm intervals [58]. Surgical procedures were performed by the first author between 1993 and 2016 on 61 patients.…”