A team led by Dr. Beom Jeon, from the Seoul National University Hospital, studied the long-term effects of deep brain stimulation on pain in 24 Parkinson patients. The researchers measured patients' pain before surgery and eight years later.
Sixteen of the patients experienced pain before surgery when not taking medication. Their average pain score was 6.2 on a scale of 1 to 10 where 10 represents the most pain, the researchers reported.
Jeon's team found that the pain suffered before surgery had improved or disappeared eight years later.
But 18 patients developed new pain during the follow-up period.
New pain affected 47 body parts, with an average pain score of 4.4. For more than half of these patients, the new pain was described as aching and cramping in joints or muscles, the researchers said.
This new muscle pain needs to be researched separately, the researchers said, noting it didn't seem to respond to deep brain stimulation.
"We found that pain in [Parkinson's disease] is improved by deep brain stimulation, and the beneficial effect persists after a long-term follow-up of eight years," the researchers concluded.
"In addition, new pain developed in most of the patients during the eight-year follow-up period. We also found that deep brain stimulation is decidedly less effective for musculoskeletal pain and [that pain] tends to increase over time. Therefore, musculoskeletal pain needs to be addressed independently," the researchers concluded.
The authors of an accompanying editorial said larger trials are needed with longer follow-up. "For now we have learned that [deep brain stimulation] does not take the ouch out of [Parkinson disease]," they wrote.
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