By Will Boggs MD
NEW YORK (Reuters Health) - Transcranial magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy improves medication-refractory essential tremor through three years of follow-up, according to results from a randomized controlled trial.
"As we continue to tailor patient care to individualized variables, knowing that MRgFUS has meaningful benefit in terms of tremor reduction and improvement in quality of life at 3 years shows that it should be at least considered for all patients with severe essential tremor," Dr. Binit B. Shah of the University of Virginia, in Charlottesville, told Reuters Health by email.
Early findings from this trial comparing MRgFUS ventral intermediate nucleus thalamotomy to sham treatment demonstrated significant tremor suppression, improved disability and overall quality of life, and a favorable safety profile in the thalamotomy group at three months, 12 months, and 24 months.
In the current study, Dr. Shah and colleagues assessed the durability of tremor relief and quality of life improvement at three years' follow-up in 75 patients who underwent unilateral transcranial MRgFUS thalamotomy during the randomized blinded phase or in an unblinded fashion in the crossover phase of the trial.
The primary outcome for the trial, the median hand combined tremor-motor score, improved from a baseline value of 20 to 8 at six months and remained at 8 at 36 months, a 56% median improvement from baseline, the researchers report in Neurology, online November 20.
The disability score also improved by 63%, from a median value of 16 at baseline to 6 at three years after MRgFUS thalamotomy.
MRgFUS treatment reduced postural tremor scores by a median 100% and improved quality-of-life scores by 50% at 36 months.
For the 49 patients present at both six and 36 months, the hand combined tremor-motor score had increased by a median 1 point at 36 months, had increased by a median 2 points at 36 months, and posture and quality-of-life scores had not changed significantly.
At 36 months, 58% of the patients had a hand combined tremor-motor score improvement of at least 50% from baseline, compared with 64% at 24 months and 61% at 12 months.
There were no new treatment-related adverse events between 24 and 36 months of follow-up, and no previous adverse events worsened during this interval.
Among the 76 patients who participated in the randomized controlled trial, adverse events still reported at the end of the third follow-up year included paresthesias in 11, imbalance in five, unsteadiness in two, muscle weakness in two, and ataxia, slow movements, dysmetria, taste disturbances, and fatigue in one participant each. All such events were mild or moderate.
"Where MRgFUS fits into the management of essential tremor is an evolving concept," Dr. Shah said. "In healthier patients who are increasingly disabled by tremor," MRgFUS provides benefits lasting at least as long as those from deep brain stimulation (DBS) and helps avoid many "of the hardware and battery-life issues that can deter patients from DBS."
"On the other end of the spectrum, as a palliative procedure in patients with significant medical and neurological illness, MRgFUS may provide a viable option for tremor reduction in patients in whom general anesthesia could be problematic," he said. "The caveat here is that MRgFUS has been shown to be effective and fairly safe as a unilateral treatment. For patients with bilateral, severe tremor, deep brain stimulation remains the gold-standard option."
The study was supported by Insightec, which makes the MRgFUS system used in the study. The company participated in all aspects of the study, including manuscript preparation. Several of Dr. Shah's coauthors report ties to Insightec.