• Nathalie André-Obadia, Patrick Mertens, Taïssia Lelekov-Boissard, Afif Afif, Michel Magnin, and Luis Garcia-Larrea.
• Neurophysiology & Epilepsy Unit, Neurological Hospital P. Wertheimer, Hospices Civils de Lyon, France; Inserm U 1028, NeuroPain team, Neuroscience Research Center of Lyon (CRNL), Lyon-1 University, France.
• Pain Physician. 2014 Jan 1; 17 (1): 53-62.

BackgroundA 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.ObjectivesThis 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 DesignAnalysis of the long-term evolution of pain patients treated by epidural motor cortex stimulation, and predictive value of preoperative response to rTMS.SettingUniversity Neurological Hospital Pain Center.MethodsPatientsTwenty patients suffering chronic pharmaco-resistant neuropathic pain.InterventionAll patients received first randomized sham vs. active 20 Hz-rTMS, before being submitted to MCS surgery.MeasurementPostoperative 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.ResultsPain 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 MCS-related 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.LimitationsLimited 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.ConclusionsHalf 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).

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