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Long lasting antalgic effects of daily repetitive transcranial magnetic stimulation in neuropathic pain
  1. S Owen1,
  2. T Z Aziz2
  1. 1University Department of Physiology, University of Oxford, Oxford, UK
  2. 2Nuffield Department of Surgery, University of Oxford, Oxford, UK
  1. Correspondence to:
 Professor T Z Aziz
 Department of Neurosurgery, Radcliffe Infirmary, Woodstock Road, Oxford OX2 6HE, UK; tipu.azizphysiol.ox.ac.uk

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Prolonged and significant pain relief can be achieved with repetitive TMS

Since the report in 1990 by Tsubokawa1 that epidural motor cortex stimulation was effective in alleviating neuropathic pain, there have been multiple reports of the technique with varying results. A predictive test to improve outcome would have been invaluable in selecting patients for such procedures. Transcranial magnetic stimulation (TMS) in single sessions were reported to have a predictive effect by Migita2, Canavero3, Lefaucheur4, and others. However, the effects of such a technique over longer periods of time in a large number of patients have not been reported until now (Khedr et al5; this issue, pp 833).

Using a higher frequency of stimulation (20 Hz for five daily sessions) Khedr et al were able to achieve an average 45% pain reduction compared with sham stimulation (5%), as assessed by visual analogue score (VAS) and Leeds assessment of neuropathic symptoms and signs (LANSS) questionnaires. The reduction is significantly higher than that reported by Lefaucheur4 using 10 Hz stimulation. The number of patients studied was large—24 had trigeminal neuralgia, and 24 had post stroke pain. Significant pain relief occurred up to 2 weeks after the last session and the degree of pain relief increased with the number of sessions.

This paper is significant for a number of reasons. At first glance it only confirms what has already been reported. However, it goes further. Prolonged and significant pain relief can be achieved with repetitive TMS. In this series the majority had head, face, and arm pain, either from trigeminal neuralgia or stroke. There were a few non-responders and I wonder whether this is related to stroke as the authors point out. Certainly this has been our experience. It may also be more difficult to achieve pain relief in the leg region or to cover hemi body pain that occurs after stroke due to inaccessibility of the leg area to TMS. It is also of interest that although stimulation was applied over the hand and arm area there was a good response in patients with facial pain. It is also of interest that although motor cortex stimulation generally is applied at about 40 Hz across groups, TMS uses much lower frequencies—20 Hz in this study.

This may well establish higher frequency TMS as an effective methodology of screening patients for implantation of motor cortex stimulation and since the effects are rather prolonged, may even prove to be a methodology that may be useful as an outpatient treatment for certain pain patients.

Perhaps, given the effectiveness of this procedure, the afflicted patients have some recourse to continued TMS in Egypt. This would also answer the question of whether this therapy could be offered to many patients without recourse to surgery.

Prolonged and significant pain relief can be achieved with repetitive TMS

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