Tremors are characteristic of movement disorders like ET and PD, two progressive conditions that affect millions of people worldwide.
Previous treatment options for reducing them in patients who have not responded to medical therapy include deep brain stimulation, a surgical procedure that involves implanting a small electrode in the brain connected to a pulse generator that is implanted in the chest like a pacemaker.
A more recently-available option is magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy, an incisionless interventional radiology procedure.
It involves focused beams of sound energy being used to heat and destroy a small part of a structure in the brain called the thalamus. The procedure provides relief to the opposite side of the body, meaning that treatment to the right side of the brain would relieve tremors on the left side of the body, and vice versa.
As a minimally invasive approach, focused ultrasound has advantages over deep brain stimulation, including a reduced risk of complications from bleeding and infections, according to study lead author Federico Bruno, a radiologist from the University of L’Aquila in Italy.
“Another advantage is the immediate effect this treatment provides, unlike deep brain stimulation which requires a break-in period for the electrostimulation,” he says. “Additionally, treatment with MRgFUS requires shorter hospitalisation and is a fairly well-tolerated procedure even by more fragile patients.”
For the new study, Dr. Bruno and colleagues enrolled 39 patients, with an average age of 64.5 years, with disabling tremors that had not responded to treatment.
The people in the study group, including 18 with ET and 21 with PD, had experienced symptoms for an average of more than 10 years.
The researchers evaluated the patients for tremor severity and quality of life before MRgFUS thalamotomy, immediately after treatment and over the course of the ensuing year.
They found that 37 of 39 patients, or 95 per cent, had substantial and immediate reduction of tremor. These reductions
in tremor were sustained in follow-up evaluations. Quality of life evaluation showed substantial improvement in both the ET and PD groups.
“The study we present reports our experience of over a year in the treatment of tremor by thalamotomy with focused ultrasound,” Dr. Bruno says.
“It is worth noting that we had a high number of patients with Parkinson’s disease in our series, compared to previously published data, where the procedure was used mainly in the treatment of essential tremor patients.”
Currently, MRgFUS thalamotomy is only available at a limited number of sites worldwide, but may become more widespread as research findings supporting its use are published. Improvements in neuroimaging techniques that allow for greater precision and detail in planning, implementation and monitoring over time of the treatment could also expand its availability.
“The clinical application of this technique for neurological diseases is an absolute novelty – the clinical use was approved by the FDA less than three years ago.
“Few patients know of this treatment option so far, and there are not many specialised centres equipped with the required technology.” Future research in this area includes the possibility of treating both sides of the thalamus. MRgFUS is also being explored in areas beyond movement disorders, Dr. Bruno says.
Several preclinical studies and clinical trials are looking at the technique for the treatment of other neurological conditions like neuropathic pain, epilepsy and obsessive- compulsive disorders, as well as for the treatment of brain tumours.