Noninvasive brain stimulation to treat chronic pain
In this Cochrane review, researchers in Australia and the UK evaluated the evidence for directly altering brain activity with electrical stimulation to reduce chronic pain.
First, the details.
- 33 studies or adults with chronic pain of at least 3-months in duration were reviewed.
- 19 studies of repetitive transcranial magnetic stimulation (rTMS) — a noninvasive method to cause depolarization in the nerves of the brain.
- 8 studies of cranial electrotherapy stimulation (CES) — a small, pulsed electric current across a patient’s head.
- 6 studies of transcranial direct current stimulation (tDCS) — constant, low current delivered directly to the area of interest via small electrodes.
- Where possible data were used to conduct meta-analyses.
- Studies included a sham stimulation control group.
And, the results.
- Only 1 study was judged as being at low risk of bias.
- rTMS
- Pre-specified subgroup analyses suggested that low-frequency stimulation is ineffective.
- A short-term effect on pain of active high-frequency stimulation of the motor cortex in single-dose studies was reported.
- This equated to a 15% reduction in pain, which did not clearly exceed the pre-established criteria for a minimally clinically important difference.
- CES
- No significant difference was found between active and sham stimulation.
- tDCS
- There was no difference between active and sham stimulation.
- Pre-specified subgroup analysis of tDCS applied to the motor cortex suggested superiority of active stimulation over sham.
- Non-invasive brain stimulation appears to be associated with minor and transient side effects.
The bottom line?
The authors concluded, “Single doses of high-frequency rTMS of the motor cortex may have small short-term effects on chronic pain. The effects do not clearly exceed the predetermined threshold of minimal clinical significance. Low-frequency rTMS is not effective in the treatment of chronic pain.
Regarding the other treatments, “There is insufficient evidence from which to draw firm conclusions regarding the efficacy of CES or tDCS. The available evidence suggests that tDCS applied to the motor cortex may have short-term effects on chronic pain and that CES may be ineffective.”
There’s a need for better studies.
4/18/11 18:02 JR
