Differential efficacy of electric motor cortex stimulation and lesioning of the dorsal root entry zone for continuous vs paroxysmal pain after brachial plexus avulsion.

BACKGROUND

Pain after traumatic brachial plexus avulsion (BPA) has 2 distinct patterns: continuous burning pain and paroxysmal shooting pain. Lesioning of the dorsal root entry zone (DREZotomy) is more effective for paroxysmal than continuous pain. It is unknown, however, whether electric motor cortex stimulation (EMCS) has a differential effect on continuous vs paroxysmal BPA pain.

OBJECTIVE

To analyze the differential effect of EMCS and DREZotomy on continuous vs paroxysmal BPA pain in a series of 15 patients.

METHODS

Fifteen patients with intractable BPA pain underwent DREZotomy alone (n = 7), EMCS alone (n = 4), or both procedures (n = 4). Pain intensity was evaluated with the Visual Analog Scale, and separate ratings were recorded for paroxysmal and continuous pain. Pain relief was categorized as excellent (> 75% pain relief), good (50%-75%), or poor (< 50%). Favorable outcome was defined as good or better pain relief.

RESULTS

Eight patients had EMCS; 7 were followed up for an average of 47 months. Of those 7 patients, 3 (42%) with continuous pain had favorable outcomes compared with no patients with paroxysmal pain. Eleven patients had DREZotomy; 10 were followed up for an average of 31 months. Of those 10 patients, 7 (70%) with paroxysmal pain had favorable outcomes compared with 2 (20%) with continuous pain.

CONCLUSION

EMCS was ineffective for paroxysmal pain but moderately effective for continuous pain. DREZotomy was highly effective for paroxysmal pain but moderately effective for continuous pain. It may be prudent to use EMCS for residual continuous pain after DREZotomy.