Deep brain stimulation relieves chronic Parkinson’s pain
MedWire News: Subthalamic nucleus deep brain stimulation (STN-DBS) may help relieve pain associated with Parkinson's disease (PD), say researchers.
Daniel Ciampi de Andrade (University of São Paulo, Brazil) and colleagues found that STN-DBS specifically modulates small fiber-dependent sensory threshold in PD.
"Nonmotor symptoms (NMS) such as depression, pain, sexual problems, bowel incontinence, and sleep disorders are present in a large majority of PD patients, and their importance has been increasingly recognized in recent years…," they explain. "Chronic pain (CP) is one of the most frequent NMS, and it was found that 62% of a cohort of 450 PD patients had CP."
The study, published in Pain, included 25 patients with PD (mean age 58.8 years) and 35 age-matched healthy controls. All the participants were evaluated for changes in painful and nonpainful sensory thresholds caused by the STN-DBS. Both large and small fiber-mediated sensory thresholds were assessed using a battery of quantitative sensory testing (QST) to compare the on-stimulation and off-stimulation states in each patient.
The researchers found that CP, which was assessed using pain questionnaires and scores, was present in 72% of patients before surgery but that this reduced to 36% after surgery, a statistically significant decrease.
The patients with PD showed a significantly increased sensitivity to innocuous thermal stimuli and mechanical pain, but a reduced sensitivity to innocuous mechanical stimuli, compared with the controls, in both on- and off-stimulation states.
The QST values for large fiber-mediated sensations did not change in the PD patients between the on-stimulation and off-stimulation states. However, the researchers reported an increased sensitivity to innocuous thermal stimuli, and a reduced sensitivity to mechanical or thermal pain in the PD patients when the stimulator was switched on.
"This study showed that STN-DBS was associated with a significant relief of ongoing CP and changes in cutaneous sensory thresholds, mostly thermal innocuous and noxious ones," conclude the researchers.
"In particular, the modulation of heat and warm detection was related to DBS-induced motor improvement. These data will add to the growing knowledge on the mechanisms of action of STN-DBS on NMS in PD."
By Chloe McIvor