Is Pain a Symptom of Parkinson's Disease?
by Michael Rezak, MD, PhD
Of the many symptoms of Parkinson's disease (PD) that can be disabling, pain can be among the most severe. Not only is pain typically not recognized as a manifestation of PD thereby resulting in tedious, extensive and often fruitless evaluations to identify the etiology, but once identified as PD related, effective treatment can be elusive.
It is estimated that approximately 10% of people with PD will have pain as their initial presenting symptom, preceding any motor complaints. Furthermore, recent published data suggests that up to 50% of patients manifest significant painful sensations during the course of their PD. The challenge for physicians and patients is to recognize when these complaints represent a component of another serious illness and when it may be a non-motor feature of PD. This is especially difficult because the painful symptoms may mimic other painful conditions such as a low back pain, sciatica, joint aching, dental pain, gynecologic discomfort and abdominal discomfort.
Given the impact of pain on quality of life, the APDA National Young Onset Center conducted an informal, online survey which, although unscientific, supports the notion that there is a high prevalence of pain in those patients impacted by PD. Overall, the survey documents that the vast majority of respondents (82%) experienced pain with their illness and the pain they experienced is often severe. Interestingly, for younger patients (those under the age of 60), the most frequently cited areas of pain were the shoulder and foot - 65% and 53% respectively. For those over the age of 60, it was the neck and/or back (both of which were cited by approximately 50% of respondents).
Pain in PD can be related to peripheral mechanisms e.g. muscle contractions (dystonia), orthopedic problems etc., for which treatment can be targeted at these problems. It can also arise from "central" mechanisms, i.e. abnormal sensory processing in the brain, which can be more difficult to treat. Although uncommon, examples of central pain syndromes include oral and genital burning as well as numbness and tingling of various body parts. Rarely, pain can even occur from the use of dopaminergic medications. Deciphering the cause of the pain takes dedicated "detective work" on the part of the neurologist.
Of the 247 total respondents, 77% reported that they (and/or their physicians) believe that their pain is due to their PD. Not surprisingly, a much higher percentage of younger patients (84%) attribute their pain to their PD than do those in the older group (62%). Additionally, PD patients have been found to have multiple sources for their pain. This too was shown to vary by age with common diagnosis of dystonia in younger patients (54%) and arthritis in older patients (64%). A majority of respondents (80%) indicated that their pain is often correlated to their motor state. If a pattern of painful sensation emerges that correlates to "off" episodes or if the pain is relieved with dopaminergic medication, more credence can be given to the fact that the pain is PD related. Often this is not the case necessitating a complete medical evaluation to rule out other serious causes. Physicians caring for PD patients should be aware of the high prevalence of pain as a part of PD as well as possible treatment options.
When a PD patient faces pain as a symptom, a thorough and frank discussion with the neurologist should take place. If there is a correlation between pain exacerbation and dosing intervals, the neurologist should be made aware of this so that he can make appropriate medication regimen adjustments. Our survey did reveal that a number of traditional and alternative medicine strategies have been tried and have been successful for some individuals and I would encourage the utilization of these modalities with the advice and consent of the treating physician.
Our understanding of how sensory signals are disordered in PD is just beginning to be understood and research is accelerating into understanding this better. This research will ultimately lead to improved treatment options for this serious non-motor symptom in PD.
Dr. Rezak is Medical Director of the APDA National Young Onset Center, Director of the Movement Disorders Center, and Co-Director of the DBS Program of the Neurosciences Institute at Central DuPage Hospital in Winfield, IL. Dr. Rezak is on the Speaker's Bureau for Allergan, Novartis, Medtronic, Teva, and GlaxoSmithKline.