Would this help for post stroke tremors?
http://www.medpagetoday.com/Neurology/GeneralNeurology/59856?
Focused ultrasound thalamotomy produced short-term improvement in hand
tremor in patients with essential tremor, researchers reported.
In a randomized sham-controlled trial, patients who received the
therapy had greater improvements in physician-rated hand tremor scores
at 3 months (47% improvement versus 0.1% improvement,
P<0.001),
Jeffrey Elias, MD, of the University of Virginia Health Sciences Center, and colleagues
reported in the New England Journal of Medicine.
But editorialist
Elan Louis, MD,
of Yale, noted that data reported in a supplementary appendix
(available only online) showed that overall tremor scores (i.e., not
just hand tremor) rose by 23% and physician-rated tremor scores rose by
38% at month 12, relative to their nadir at one month post-treatment.
"Whether this loss of efficacy, which is also seen to some extent
with deep-brain stimulation, is due to disease progression or tolerance
is not clear," Louis wrote, adding that he considered the former "less
likely."
The investigators also noted that the treatment came with sensory and gait disturbances affecting roughly one-third of patients.
The
FDA approved the device used in the current study for MRI-guided focused ultrasound thalamotomy in essential tremor last month. The current study was the manufacturer's primary registration trial.
The procedure involves ablating tissue with high-intensity sound
waves. Medical therapies for essential tremor include beta blockers --
particularly propranolol -- the antiepileptic drug primidone, and
other drugs that enhance GABA transmission.
However,
efficacy of these treatments is limited, so some patients try deep
brain stimulation, which is the standard surgical procedure for this
condition. It was approved by the FDA in 1997 for this indication, but
there have been few randomized controlled trials of the technology, so
evidence of its efficacy remains scant, Elias and colleagues wrote.
To assess whether focused ultrasound thalamotomy could provide
another option for patients with moderate-to-severe essential tremor who
don't responded to other medical therapies, the researchers enrolled 76
patients, mean age 71 with a mean disease duration of 17 years, and
randomized them in a 3:1 fashion to unilateral focused ultrasound
(which, if effective, would improve tremor in only the contralateral
hand) or to a sham procedure.
The primary outcome was difference in change from baseline to 3
months in hand tremor, rated on a 32-point scale in which higher scores
indicate a more severe tremor.
After 3 months, patients in the sham group were allowed to cross over to the active treatment.
Overall, the researchers found that scores improved more after
focused ultrasound than with the sham procedure (from scores of 18.1 to
9.6 versus 16 to 15.8) -- a 47% improvement compared with a 0.1%
improvement, and a mean difference of 8.3 points (
P<0.001). No significant change in tremor scores for the ipsilateral hand was seen in treated patients.
The improvement in the focused ultrasound group persisted at one year, with a 40% improvement from baseline, they reported (
P<0.001).
Patients who crossed over into the treatment group improved by 55% at 3 months and by 52% at 6 months, they found (
P<0.001).
In terms of secondary outcomes, those who had focused ultrasound had
greater improvements in disability (62% reduction versus 3% reduction,
P<0.001) and in quality of life (46% improvement versus 3% improvement,
P<0.001) at 3 months.
The researchers did note that higher rates of adverse events in
thalamotomy group included gait disturbance (36%) and paresthesias or
numbness (38%), and these persisted at one year in 9% and 14% of
patients, respectively.
In the
accompanying editorial,
Louis highlighted "several important concerns." First, the study was
limited to 1 year, so the benefits further down the road aren't clear,
which requires more studies with longer follow-up, he said.
In
addition to the overall tremor scores and physician-reported tremor
scores increasing, Louis noted that not all patients benefitted from the
procedure, with a percent change below 20% in 9 of 56 patients. Some
skulls may be too thick for the procedure to work properly, he added.
Unlike with deep-brain stimulation, he warned, a thalamotomy creates a
fixed brain lesion -- and altered sensation remained in 14% of
patients at 1 year, he wrote.
"Even with these concerns and caveats, pros and cons, the procedure
will take its place among other surgical procedures for medically
refractory essential tremor," Louis wrote. "Given the perception that it
is less invasive than other approaches because it does not involve burr
holes and intracerebral electrodes, as well as the evidence that
patients with essential tremor are perhaps particularly harm avoidant,
the procedure may allow more patients to avail themselves of a surgical
option for the treatment of this often disabling disease."
He also called for a head-to-head comparison with deep-brain stimulation.
-
Reviewed by
Robert Jasmer, MD
Associate Clinical Professor of Medicine, University of California,
San Francisco
