Is life better after motor cortex stimulation for pain control? results at long-term and their prediction by preoperative rTMS

Background: a positive effect of motor cortex stimulation (mcs) (defined as subjective estimations of pain relief ≥ 30%) has been reported in 55 - 64% of patients. repetitive magnetic cortical stimulation (rtms) is considered a predictor of mcs effect. these figures are,however,mostly based on subjective reports of pain intensity,and have not been confirmed in the long-term. objectives: this study assessed long-term pain relief (2 - 9 years) after epidural motor cortex stimulation and its pre-operative prediction by rtms,using both intensity and quality of life (qol) scales. study design: analysis of the long-term evolution of pain patients treated by epidural motor cortex stimulation,and predictive value of preoperative response to rtms. setting: university neurological hospital pain center. methods: patients: twenty patients suffering chronic pharmaco-resistant neuropathic pain. intervention: all patients received first randomized sham vs. active 20hz-rtms,before being submitted to mcs surgery. measurement: postoperative pain relief was evaluated at 6 months and then up to 9 years post-mcs (average 6.1 ± 2.6 y) using (i) pain numerical rating scores (nrs); (ii) a combined assessment (cpa) including nrs,drug intake,and subjective quality of life; and (iii) a short questionnaire (howru) exploring discomfort,distress,disability,and dependence. results: pain scores were significantly reduced by active (but not sham) rtms and by subsequent mcs. ten out of 20 patients kept a long-term benefit from mcs,both on raw pain scores and on cpa. the cpa results were strictly comparable when obtained by the surgeon or by a third-party on telephonic survey (r = 0.9). cpa scores following rtms and long-term mcs were significantly associated (fisher p = 0.02),with 90% positive predictive value and 67% negative predictive value of preoperative rtms over long-term mcs results. on the howru questionnaire,long-term mcsrelated improvement concerned discomfort (physical pain) and dependence (autonomy for daily activities),whereas disability (work,home,and leisure activities) and distress (anxiety,stress,depression) did not significantly improve. limitations: limited cohort of patients with inhomogeneous pain etiology. subjectivity of the reported items by the patient after a variable and long delay after surgery. predictive evaluation based on a single rtms session compared to chronic mcs. conclusions: half of the patients still retain a significant benefit after 2 - 9 years of continuous mcs,and this can be reasonably predicted by preoperative rtms. adding drug intake and qol estimates to raw pain scores allows a more realistic assessment of long-term benefits and enhance the rtms predictive value. the aims of this study and its design were approved by the local ethics committee (university hospitals st etienne and lyon,france).