Dorsal rhizotomy is a procedure where the sensory roots are divided either intradurally or extradurally. According to Nashold (1991) a single one or two level root rhizotomy may be appropriate when the pain is localized as in those patients with paraparesis and single root pain. Moreover, Nashold (1991) reported the Dorsal Root Entry Zone (DREZ) procedure was more likely to be successful in these patients.
In the Falci et al. (2002) study, individuals were divided into two treatment groups: the first nine patients underwent DREZ micro-coagulation using recorded spontaneous neuro-electrical hyperactivity in as a guide; while the second group underwent DREZ micro-coagulation using both the recorded spontaneous and evoked hyperactivity as a guide. Individuals were followed up to six years post-surgery and pain was measured using the VAS. The study found that more participants (50% vs. >80%) in the second group reported 100% pain relief than those in the first group.
Chun et al. (2011) reported on 38 individuals treated with the procedure, between 2003 and 2008. These individuals suffered from various types of neuropathic pain including segmental versus diffuse, mechanical versus thermal or a combination of both, and intermittent versus continuous pain. Previous management with medication had proven unsuccessful. After surgery, individuals were followed for a period ranging between 19 and 84 months (average of 42 months) to measure the degree of pain relief. At follow-up, individuals were asked to rate the intensity of their pain using the VAS. Pain relief was considered by the authors to be “good” if pain was reduced by more than 75%, “fair” if it was reduced by 25-75% and “poor” if pain was reduced less than 25%. Individuals with intermittent pain and continuous pain achieved high rates of good pain relief (78% and 80%, respectively).9
Notably, Nashold et al. (1990) reported 14 of 18 individuals (77%) with paraplegia who underwent cyst drainage and the DREZ surgical procedure reported pain relief following surgery. In general, approximately 50% or more of the patients across these case series achieved greater than 50% pain relief or experienced no pain-related activity limitations and no need for narcotics following the surgery (Friedman & Nashold 1986; Nashold et al. 1990; Rath et al. 1997; Sampson et al. 1995; Sindou et al. 2001; Spaic et al. 1999; Spaic et al. 2002). However, all of these were retrospective, uncontrolled reports with obvious methodological limitations, such as ill-defined eligibility criteria (i.e., potential selection bias) and inadequate outcome measurement which limits the generalizability of the results.
There is level 2 evidence (from one prospective controlled trial, one pre-post study, and seven case series studies: Falci et al. 2002; Chun et al. 2011; Sindou et al. 2001; Spaic et al. 1999, 2002; Rath et al. 1997; Sampson et al. 1995; Bashold et al. 1990; Friedman & Nashold 1986) to support the use of the DREZ surgical procedure to reduce pain post SCI. It may be that some populations (segmental pain) are more likely to benefit from this procedure.