MGH Martinos Center for Biomedical Imaging 2017 | Page 11

Can Acupuncture Treat Carpal Tunnel Syndrome?
Researchers tackle a modern-day malady with an ancient medical practice
Though it predates current understandings of physiol- Is it real, or is it just a sham?
ogy by several millennia, acupuncture often provides
measureable improvements in health outcomes, par- The findings helped to address a longstanding question
ticularly in the area of chronic pain.
with acupuncture: does the technique work primarily
by placebo effect or is it something more?
Precisely how it does this has long been a mystery. At
the same time, separating out direct needle stimulation The question has been especially hotly debated over the
and placebo effects has been a focus of much debate.
years because real acupuncture techniques have been
shown to be only slightly more effective than sham ones
In a study reported in the journal Brain, a team of inves- for many chronic pain conditions.
tigators based at the MGH Martinos Center explored
these questions, probing the relationship between acu- The Brain study offers insight into the differences
puncture and the alleviation of pain and shedding new between the two. Sham acupuncture may produce
light on how exactly the practice works.
a stronger placebo effect than a pill, for example,
because it sends inputs to the brain via skin receptors
The study, led by Vitaly Napadow, director of the Center and is coupled with a specific ritual. Nonetheless, the
for Integrative Pain Neuroimaging at the Martinos symptom improvement produced by sham treatment
Center, focused on the mechanisms of acupuncture in for conditions like carpal tunnel syndrome might derive
carpal tunnel syndrome, a neuropathic pain disorder from entirely different mechanisms than those elicited
that has objective measures of nerve dysfunction as by real acupuncture, the mechanisms of which may
well as subjective reports of pain. The latter are more more specifically target carpal tunnel syndrome patho-
susceptible to placebo effects.
physiology.
Using fMRI, Napadow and colleagues performed brain
imaging in three groups of carpal tunnel patients: two
receiving real electro-acupuncture and the other receiv-
ing a “sham” treatment, with placebo needles that don’t
penetrate the skin.
They found that, while both real and sham acupuncture
alleviated the symptoms of carpal tunnel syndrome
at the wrist itself, real acupuncture also improved
outcomes by remapping the areas of the brain associ-
ated with pain. Importantly, these changes in the brain
proved to be predictors of long-term symptom relief in
the carpal tunnel patients.
“Sham acupuncture may ‘work’ by modulating known
placebo circuitry in the brain,” Napadow says. “In
contrast, real acupuncture may improve carpal tunnel
symptoms by rewiring the primary somatosensory
cortex, in addition to modulating local blood flow to
the peripheral nerve in the wrist.
“In other words, both peripheral and central neuro-
physiological changes in carpal tunnel syndrome may
be halted or even reversed by electro-acupuncture
interventions that provide more prolonged and regu-
lated input to the brain. This is something that future,
longer-term neuroimaging studies should explore.”
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