For nearly ten years, there has been evidence that stimulation of the motor cortex can help central pain. TCDS is “trans-cranial direct current stimulation”.
There seems to be solid evidence that stimulation of the motor cortex has the potential to help central pain. There is even evidence now that this may be done without invasive brain surgery.
Stimulation of the motor cortex for central pain has a bit of a checkered history. One painonline author, who has central pain, underwent transcranial stimulation without benefit many years ago. For a time then, not much attention was paid to such things. Then, such stimulation was moved from the somatosensory cortex to the motor cortex and the method of stimulation was open cranial surgery. Such invasive methods instinctually caused concern, but to nearly everyone’s amazement, there was some pretty solid evidence that it worked.
There was enough data to persuade Sergio Canavero, a very famous researcher in Central Pain to perform open stimulation in Italy. While the benefit was achieved in most, in one patient, the stimulation created a phantom arm, and in that phantom was severe central pain. This really put the brakes on. One had to suspect other doctors were also getting phantoms but perhaps only Canavero, noted for his honesty and candor, was actually reporting the problem. There was no way to be sure of anything and so everyone pretty much sat back and waited.
To be sure, there were those who continued to administer open motor cortex stimulation, but the reports were never quite clear or explicit enough to make sure what had happened to Canavero was not also happening occasionally to others. The result was that open stimulation never really caught on.
The work did achieve the unlikely but true realization that somehow the motor cortex was involved in central pain. PET, SPECT, and fMRI imaging has since confirmed this. This gave a rational basis for stimulating a motor part of the brain to benefit a SENSORY function. It still sounds impossible, but stranger things have happened in brain research.
Eventually some researchers found a way to pass enough current into the brain with the skull closed to discover that central pain could be helped, PROVIDED the patients were carefully selected for. The big problem is that nearly all post SCI patients with central pain also have mechanical pain of some variety which is filtered through the injured sensory apparatus, so that it fools the doctor into thinking THAT is central pain, when it is merely mechanical pain masquerading.
And so, CAREFUL patient selection must be used. Harvard has credibility in pain research and so it is with interest that we report a study from a rather large group at Harvard, led by Fregni, which attempted to use DC current with the anode (negative) end on the skull for fibromyalgia, reasoning that if it helped Central Pain perhaps it would help fibromyalgia. The study design appears very sound with sham procedures and other things we associate with well designed double blind studies. Based on this study, even fibromyalgia is helped by transcranial stimulation using direct current.
This is probably a very significant finding and should lead to greater availability of TCDS treatment of central pain as well. So far, there have been no reports of this method causing a phantom, so it may be that the non-invasive procedure is much safer.
The report can be found at “A randomized, sham-controlled, proof of principle study of transcranial direct current stimulation for the treatment of pain in fibromyalgia” Arthritis Rheum. 2006 Nov 28;54(12):3988-3998
Our thanks to Boggio at Harvard Medical School and others who continue to look for better ways to treat pain from disorders of nerves. TCDS may be coming into its own. Although it is too new to say much about it, we suspect more people would try it if they knew it was available at Harvard and also if they realized they would not have to undergo a craniotomy to utilize it. We look for more series so more definite conclusions can be drawn. Please see your own doctor about this technique and do not rely on this article nor anything at this site as medical advice.