Title:Pain in Patients with Parkinson’s Disease; A Pain-related Evoked Potential Study
Volume: 2
Issue: 1
Author(s): Masanaka Takeda, Hisao Tachibana, Fumiaki Okada, Syuhei Kasama and Hiroo Yoshikawa
Affiliation:
Keywords:
Parkinson’s disease, non-motor symptoms, motor symptoms, pain-related evoked potentials, myocardial sympathetic
degeneration, 123I-metaiodobenzylguanidine (MIBG) myocardial scintigraphy.
Abstract: Pain is a well-known non-motor symptom of Parkinson’s disease (PD) and might be related to
not only peripheral factors but also abnormal processing in the central nervous system (CNS). The aim of
this study is to investigate dysfunction of the central processing of pain, and examine the relationships between
abnormal processing of pain and motor or non-motor symptoms of PD. To induce pain-related
evoked potentials in 23 PD patients and 12 healthy controls, we activated Aδ fibers using a push-pin type
needle electrode inserted in the epidermis. Evoked potentials were recorded from the Cz electrode at the index finger and
second toe. The Hoehn-Yahr stage, Unified Parkinson’s Disease Rating Scale (UPDRS), Self-rating Depression Scale
(SDS), and Mini Mental State Examination (MMSE) were evaluated. In addition, MIBG myocardial scintigraphy was performed
and early and delayed heart-to-mediastinum (H/M) ratios were examined. The N1-P1 peak-to-peak amplitudes,
which are thought to originate from the anterior cingulate cortex and insula, were significantly lower in PD patients than
in the controls for both the upper and lower limbs (both P<0.01). The N1-P1 amplitudes for the upper limbs were significantly
correlated with the H/M ratio (P<0.05). The N1-P1 amplitudes did not correlate with the severity of clinical parameters
such as the Hoehn-Yahr stage or UPDRS and SDS or MMSE. These results may reflect abnormal central processing
of pain in PD patients, which appears to be independent of the clinical features and severity of motor and nonmotor
symptoms except for degeneration of the myocardial sympathetic nerve.
