The study was sponsored by the neuromodulation division of St. Jude Medical Inc. All of the authors reported numerous financial disclosures, including six who are paid consultants for St. Jude Medical.
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Approach Should Stimulate Competition
This first study of a constant-current deep brain stimulator may nudge device companies toward developing more – and better – forms of the equipment, Dr. Jens Volkmann wrote in an accompanying commentary (Lancet Neurol. 2012 Jan. 11 [doi:10.1016/S1474-4422(12)70002-9]).
"Although the novel device might not mark a technological breakthrough in neurostimulation per se, diversification in this specialty, which has been dominated by one device manufacturer since the introduction of DBS in the late 1980s, is welcome," he wrote.
Although there are no comparative studies, both types of stimulation appear to provide long-lasting, reliable benefits. "The electrode-tissue interface is formed within the first weeks after the surgery, and during this settling in period, changes in electrode impedance might necessitate amplitude adjustments when a constant-voltage device is used. Thereafter, clinical effects and stimulation parameters remain remarkably constant for years, irrespective of which mode of stimulation is being used," he wrote.
The study also points to one of the technique’s biggest drawbacks: a rapid, mild decline in postsurgical frontal executive function that was present in both groups. This is a well-known adverse effect, but one that may be solvable with more research, Dr. Volkmann suggested.
"This finding indicates that the surgical procedure, rather than neurostimulation of the subthalamic nucleus, was responsible for this type of cognitive decline. As a result, neurosurgeons should review their practice and determine whether this adverse event results from microlesioning of the target area or of anatomical structures along the trajectory (such as the head of the caudate nucleus), which might be avoided by improved surgical technique," he said.
Hopefully, the entrance of another company and another system will spur an entrepreneurial spirit among researchers interested in deep brain stimulation therapy. "Now that competitors have become interested in neurostimulation, the investment in this area will undoubtably accelerate progress and so benefit our patients," he wrote.
Dr. Volkmann is director of the neurology clinic at University Hospital of Würzburg (Germany). He reported that he has received honoraria, consulting fees, and grant support from Medtronic and speaker honoraria from St. Jude Medical.
FROM THE LANCET NEUROLOGY