Yet the therapy Schmalfeldt hoped would offer him neuroprotection is proving fallible. While he experienced a welcomed lessening of the rigidity and slowness in his movements with DBS, his balance and gait have deteriorated significantly in the last year, he says. A positive of the treatment, he says, is that he now takes about half as much of the Parkinson's anti-tremor medication, Levodopa, than he would otherwise be taking. Over time, a patient's Levodopa dose must be increased, which causes side effects including dyskinesia, an increase in involuntary—often jerky—movement, in a majority of patients.
Other volunteers who got DBS in the trial have had better luck. "I would say my Parkinson's disease does not seem to be progressing," says Duane Cook, 56, a lawyer from Lexington, Ky., who also had the DBS device implanted. In fact, Cook, an avid exerciser, says, "My golf game has continued to improve." At this stage, it is impossible to know the impact of DBS on the disease progression in the two men.
Schmalfeldt says he has had a number of falls lately. The recent JAMA research found an increased risk of falls in patients who had DBS. What is not clear is whether DBS was responsible or whether the subjects were at higher risk because of better overall functioning and their higher level of activity. Research has suggested other DBS side effects may include post-operative psychiatric complications, like sexual disinhibition, pathologic gambling, and transient psychosis. Other DBS research, though not conclusive, has suggested side effects may include an increased risk of depression or suicide. Also, the battery must be replaced at least every five years, typically in an outpatient setting.
Though Schmalfeldt has experienced a decline in functioning, he retains a buoyant, cheeky attitude. To offer support to other Parkinson's patients and to show that "it can be done with a sense of humor," Schmalfeldt blogs about life with Parkinson's at DeepBrainDiary.com. "You have to laugh at it," he says of the inconveniences of the disease. "I call it 'taunting the monster.' "
Corrected on : Corrected on 07/16/09: An earlier version of this article misstated the name of David Charles of Vanderbilt University School of Medicine, and incorrectly described a symptom of Parkinson's disease as a side effect of the Parkinson's drug Levodopa. Also clarified was the fact that deep brain stimulation may require drilling more than one hole in the skull.