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Treatment of Chronic Neuropathic Pain by Motor Cortex Stimulation –
Results of a Prospective Controlled Trial
J.-P. Nguyen, F. Velasco, J.-P. Lefaucheur, M. Velasco, P. Brugières, B. Boleaga, F. Brito, Y. Kéravel
Introduction
Chronic motor cortex stimulation (MCS) is a thera- peutic procedure that is increasingly used for neuro- pathic pain refractory to medical treatment. However, no prospective controlled trial of the procedure has been published. Its real impact on the patient’s im- provement therefore remains controversial.
Method
This study was conducted at two different centers:
the Henri Mondor Hospital, Department of Neurosur- gery, in Créteil (France) and the Mexico General Hospital, Department of Stereotaxis and Functional Neurosurgery (Mexico). Each center recruited five patients with neuropathic pain refractory to medical treatment, and the final group was composed of six men and four women aged 29–75 years (mean: 54.7
±18 years). Three patients suffered from central pain (1, 3, 8), three from neuropathic facial pain (2, 4, 5), two from post-herpetic peripheral pain (6 and 7), and two from complex regional pain syndrome (CRPS) of the upper limb (9 and 10) (⊡ Table 10.1).
The patients were evaluated preoperatively and postoperatively (D-30, D30, D60, D75, D90, M6, M9, M12) using a 5-point verbal scale, a visual analogue scale, the McGill Pain Questionnaire, the Wisconsin
Brief Pain Questionnaire, and the Medication Quan- tification Scale. At the end of the second postoperative month, patients were randomized to two groups. In the first group, the neurostimulator was turned off between D60 and D75 (OFF period) and then turned on between D75 and D90 (ON period); the opposite sequence was applied in the second group.
Results
All scores were significantly improved by the first month and remained significantly improved until the final evaluation at M12. In addition to the total score, the various components of the MPQ were also analyzed.
Scores 2 and 3, evaluating affective and cognitive as- pects of pain, were the most significantly improved (p<0.02 and p<0.01). Activities of daily life evaluated by certain items of the MPQ (ADL item) and WBPQ (activity item) were also significantly improved (p<0.02).
Overall, patients 5 and 6 showed the least marked improvement for all scores (mean variation of all scores between D-30 and M12 of –1.9% and 15.6%).
Patient 3 presented very variable improvements for the various scores (mean of 39.7%). In all other pa- tients (1, 2, 4, 7, 8, 9, and 10), practically all scores evolved in the same direction (mean improvements of 35.1%, 68.1%, 86.4%, 69.4%, 82%, 67.7%, and 69.9%,
44 Part III · Clinical Research in Interventional Neuroscience
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cult to analyze the influence of the sequence order (ON then OFF versus OFF then ON) in this short se- ries. Overall, scores during the OFF period reflected a deterioration compared with scores recorded during the ON period, except for the VAS in the ON then OFF group and the WBPQ in the OFF then ON group. No complication related to the technique was observed.
Conclusion
The results of this study strongly suggest that motor cortex stimulation markedly contributes to the im- provement of patients in terms of pain intensity, ac- tivities of daily life, and analgesic consumption.
respectively). Six patients can therefore be considered to be markedly improved (2, 4, 7, 8, 9, and 10), two patients to be moderately improved (1 and 3), and two not improved (5 and 6).
The scores did not return to preoperative values during the OFF period, suggesting a long period of post-effect. Nevertheless, a significant improvement of the scores was observed during the ON period (ver- sus OFF period). During this blind evaluation period, the condition of all patients deteriorated slightly during stimulation, although the difference was not significant compared with the score recorded at the second month, except for the MPQ score and slightly for the VAS score. After the randomization period, patients took several months to regain their initial improvement and some patients never did. It is diffi-
⊡ Table10.1.Patients'clinicaldata e
s a
C Sex Age Etiologyofpain Distributionofpain History ] s r a e y [
e c n a b r u t s i d y t i l i b i s n e S
1 M 70 Stroke(hemorrhagic) Righthemibody 5 Hyperesthesia 2 F 75 Trigeminalneuropathy Righthemiface 5 Allodynia 3 M 57 Stroke(ischemic) Righthemibody 5 Hypoesthesia 4 M 57 Trigeminalneuropathy Lefthemiface 6 Hypoesthesia 5 F 31 Trigeminalneuropathy Righthemiface 3 Hypoesthesia 6 F 75 Peripheral(herpes) LeftintercostalT5-T6 4 Allodynia 7 M 68 Peripheral(herpes) RightC2-C3 4 Hyperesthesia 8 M 52 Stroke(ischemic) Lefthemiface 1 Allodynia 9 M 29 Peripheral(CRPS) LeftC3-T2 14 Allodynia
0
1 F 33 Peripheral(CRPS) LeftC5-C8 6 Allodynia
