is a disorder of chronic generalized muscle pain and joint stiffness
with the presence on physical exam of at least 11/18 designated tender
points. (The formal definition is a bit more involved.)
Interestingly, the term was not accepted by the AMA until
1987; the formal definition was not developed until 1990(1).
Prior to that, it was widely assumed to have a psychological
In fact, there still is a tendency in some medical circles, and in some
persons in the general population, to attribute fibromyalgia
Despite a substantial research effort (see this
compilation by FM-CFS Canada, a 14MB PDF) causes and
definitive treatments remain elusive. Thus, anything that
holds out some hope as a valid treatment is a matter of some interest.
randomized, sham-controlled, proof of principle study of transcranial
direct current stimulation for the treatment of pain in fibromyalgia.
Arthritis Rheum. 2006 Dec;54(12):3988-98.
OBJECTIVE: Recent evidence suggests that fibromyalgia
is a disorder characterized by dysfunctional brain activity. Because
transcranial direct current stimulation (tDCS) can modulate brain
activity noninvasively and can decrease pain in patients with
refractory central pain, we hypothesized that tDCS treatment would
result in pain relief in patients with fibromyalgia. METHODS:
Thirty-two patients were randomized to receive sham stimulation or real
tDCS with the anode centered over the primary motor cortex (M1) or the
dorsolateral prefrontal cortex (DLPFC) (2 mA for 20 minutes on 5
consecutive days). A blinded evaluator rated the patient’s pain, using
the visual analog scale for pain, the clinician’s global impression,
the patient’s global assessment, and the number of tender points. Other
symptoms of fibromyalgia were evaluated using the Fibromyalgia Impact
Questionnaire and the Short Form 36 Health Survey. Safety was assessed
with a battery of neuropsychological tests. To assess potential
confounders, we measured mood and anxiety changes throughout the trial.
RESULTS: Anodal tDCS of the primary motor cortex induced significantly
greater pain improvement compared with sham stimulation and stimulation
of the DLPFC (P < 0.0001). Although this effect decreased after
treatment ended, it was still significant after 3 weeks of followup (P
= 0.004). A small positive impact on quality of life was observed among
patients who received anodal M1 stimulation. This treatment was
associated with a few mild adverse events, but the frequency of these
events in the active-treatment groups was similar to that in the sham
group. Cognitive changes were similar in all 3 treatment groups.
CONCLUSION: Our findings provide initial evidence of a beneficial
effect of tDCS in fibromyalgia, thus encouraging further trials.
Note that the technique used here is not the same as repetitive
transcranial magnetic stimulation (rTMS), which has received
amount of attention here at ScienceBlogs. rTMS uses
a strong electromagnet to induce a focused current in a particular part
of the brain. In contrast, tDCS trickles a small current (1
to 2 milliamps) into the brain, using electrodes applied to the scalp.
What does tDCS actually do, on a neuronal level?
modulation of cortical excitability shifts induced by transcranial
direct current stimulation in humans
J Physiol (2003), 533.1, pp. 293-301
Transcranial direct current stimulation (tDCS) of the human motor
cortex results in polarity-specific shifts of cortical excitability
during and after stimulation. Anodal tDCS enhances and cathodal
stimulation reduces excitability. Animal experiments have demonstrated
that the effect of anodal tDCS is caused by neuronal depolarisation,
while cathodal tDCS hyperpolarises cortical neurones. However, not much
is known about the ion channels and receptors involved in these
effects. Thus, the impact of the sodium channel blocker carbamazepine,
the calcium channel blocker flunarizine and the NMDA receptor
antagonist dextromethorphane on tDCS-elicited motor cortical
excitability changes of healthy human subjects were tested.
tDCS-protocols inducing excitability alterations (1) only during tDCS
and (2) eliciting long-lasting after-effects were applied after drug
administration. Carbamazepine selectively eliminated the excitability
enhancement induced by anodal stimulation during and after tDCS.
Flunarizine resulted in similar changes. Antagonising NMDA receptors
did not alter current-generated excitability changes during a short
stimulation, which elicits no after-effects, but prevented the
induction of long-lasting after-effects independent of their direction.
In the Arthritis Rheum article, they reported an
average pain reduction of about 50%, which is pretty impressive.
As mentioned in a Medscape
summary (free registration required):
…The effects of tDCS persisted through the 21-day
follow-up period, although some diminishing of the effect was noticed
after 21 days.
“The improvement that we have seen, an average of almost 50%, indicates
a very significant reduction in pain, especially because these patients
are very refractory to other types of medical treatment,” Dr. Fregni
told Reuters Health. “Furthermore, such improvement might motivate
patients to resume usual daily activities that might enhance this
…”The sustained effects of this technique might be explained by the
synaptic effects induced by this technique,” Dr. Fregni speculated.
“Direct current stimulation has shown to induce a synaptic effect that
is similar to the phenomenon observed during learning – the long-term
potentiation (LTP). In addition, we observed that five sessions of tDCS
increased the magnitude and duration of these effects.”
As an aside, the association with LTP and learning and tDCS has been
Direct Current Stimulation during Sleep Improves Declarative Memory
The Journal of Neuroscience, November 3, 2004, 24(44):9985-9992
…Compared with placebo stimulation, anodal tDCS during SWS-rich sleep
distinctly increased the retention of word pairs (p < 0.005).
When applied during the wake retention interval, tDCS did not affect
It remains to be seen if anything clinically useful comes of this,
either for treatment of fibromyalgia, or for the improvement of memory.
Perhaps the greatest significance is in the potential for
tDCS to help us understand how the brain works.
Those of use who are eternally hopeful like to think that this is going
to work, it is going to be effective, and it is going to have minimal
if any adverse effects.
(1)The American College of Rheumatology 1990 Criteria for the
Classification of Fibromyalgia: Report of the Multicenter Criteria
Committee. Arthritis Rheum 33:160-172, 1990