Influence of deep brain stimulation and levodopa on sensory signs in Parkinson's disease.

To examine the effects of levodopa (L-dopa) and deep brain stimulation of the subthalamic nucleus (STN-DBS) on sensory symptoms and signs in Parkinson's disease (PD). Seventeen patients with PD were included. (1) Presence of sensory symptoms and (2) effects of L-dopa and STN-DBS on sensory symptoms and signs [assessed by quantitative sensory testing (QST)] were examined 6 months after starting STN-DBS. In addition, in 12 of these patients, presence of sensory symptoms prior and post STN-DBS was compared. Pain was most frequently nociceptive. In about 30-40%, pain and sensory symptoms were associated with PD motor symptoms. In most of these cases, pain responded to L-dopa. Intensity of pain was reduced post STN-DBS compared to pre STN-DBS. L-Dopa had no influence on detection thresholds, whereas STN-DBS improved thermal detection thresholds. However, thermal and mechanical pain thresholds were uninfluenced by L-dopa or STN-DBS. Although some patients reported an improvement of pain with STN-DBS or L-dopa, objectively pain sensitivity as assessed by QST was not altered by STN-DBS or L-dopa suggesting that there is no evidence for a direct modulation of central pain processing by L-dopa or STN-DBS.