Early Treatment Is Important in Parkinson's Disease

Researchers in China tested heat stimuli on patients with and without Parkinson's disease to examine the pain brain relationship.

Not treating early Parkinson’s disease (PD) could be directly linked to central nervous system dysfunction, according to research published in Parkinson’s Disease.

Researchers from China studied the reactions solicited by heat pain stimuli in untreated PD patients without pain using fMRI in order to study the non motor signs of early PD. The heat stimuli (51° C) were used for 14 patients age- and sex matched with 17 healthy controls. The PD patients were drug naïve and without pain throughout whole brain blood oxygenation of level dependent (BOLD) fMRI. The researchers also aimed to examine the relationship between pain and brain stimulation. The patients were instructed to verbally rate the intensity of the heat stimulated pain on a scale from zero (“no pain”) to 10 (“worst pain imaginable”) once they were outside the scanner.

Generally, pain in PD is believed to be a result of deficient sensory information, and prior studies have indicated that patients with PD have numerous abnormalities in somatosensory perception.

The control subjects showed strong activations to the heat stimuli in the following areas: bilateral superior temporal gyrus (STG), insula, supramarginal gyrus, putamen, contralateral superior parietal lobule, supplementary motor area, cingulate cortex, rolandic operculum, primary somatosensory cortex (S1), calcarine fissue, and ipsilateral frontal gyrus. The PD group showed significantly less activations, only in the STG, insula, S1, and putamen. The bilateral medial frontal lobe had been deactivated, as well.

“Despite the fact that the diagnosis of PD is predominantly based on clinical signs, neuroimaging offers great promise for the study of disease pathogenesis and evolution, particularly for studying brain functional changes during the early stage of disease,” the authors explained. “We provided evidence of abnormal activation in early drug naïve PD patients during a heat pain stimulus. In particular, we report observably decreased activation upon nociceptive pain (51° C) in PD subjects without pain symptoms. This result should contribute to the future clinical treatment of pain in PD patients. Furthermore, this finding supports the crucial role of the insula and STG in pain processing, as the insula is the most impaired region during perception of the heat stimulus in the PD group.”

The researchers continued that this study further supports the hypothesis that the insula and STG are crucial areas of the somatosensory circuitry in the body recruited during the period of pain.