Sleep Disturbances Closely Linked to Central Parkinsonian Pain
Research findings suggest that sleep disturbances are associated with central parkinsonian pain in patients with Parkinson disease (PD). Both sleep disturbances and pain are common disabling nonmotor symptoms of the disease.
Disturbed sleep is a common symptom of patients with PD, with its prevalence ranging widely from 40% to 90%, and poor sleep quality has been linked to depression and anxiety symptoms in this population as well as both motor and nonmotor PD symptoms. Pain affects up to 85% of patients with PD and is associated with more severe nonmotor symptoms. Both pain and sleep disturbances have a negative impact on patients’ quality of life, and previous findings have shown that they are risk factors for one another.
The current study, published in the Journal of Pain Research, aimed to determine the predictors of sleep disturbances in a cohort of patients with PD and explore the relationship between sleep disturbances and pain by pain features.
Patients with PD were recruited from the Movement Disorders Clinic of Centro Hospitalar Universitário do Porto in Portugal, and 229 participated in the study. Investigators collected data on patients’ age, sex, age at PD onset, first motor symptom, and current treatments (converted to levodopa equivalent dose).
Participants also underwent a neurological examination to assess motor symptoms, completed the Parkinson’s Disease Sleep Scale (PDSS-2), and were asked whether they had pain in the last month (and if so, answered questions about the qualities of that pain). They also completed scales to assess their anxiety and depression symptoms and quality of life.
The study authors noted that previous research has not investigated the association between sleep disturbances and central parkinsonian pain, which is the only 1 of the 5 subtypes of PD pain that is a direct consequence of the disease. It is a neuropathic pain that results from abnormal painful information processing, not from dystonia, rigidity, or musculoskeletal causes.
Of the 162 (71%) study participants reporting pain, 99 (61%) had musculoskeletal pain, 43 (27%) had dystonia-related pain, 38 (24%) had central parkinsonian pain, and 19 (12%) had radicular or neuropathic pain. None had akathitic discomfort, the fifth PD pain subtype.
The 75 patients who had sleep disturbances, as measured by a PDSS-2 score of 18 or greater, reported more severe motor symptoms, lower functional independence, and higher doses of antiparkinsonian medication. The patients with sleep disturbances also reported more frequent pain and greater pain intensity, were more anxious and depressed, and had poorer quality of life.
The frequency of sleep disturbances was 38% in patients with pain and 20% in patients without pain (P = .014). Compared with patients without pain, the frequency of sleep disturbances was significantly higher for those with central parkinsonian pain (53%; P = .001) but not for the other types of pain.
Using logistic regression, the researchers found that among patients with pain, there were higher odds of having sleep disturbances among patients with central parkinsonian pain (odds ratio, 2.25; 95% CI, 1.08-4.71; P = .031); no associations were found between sleep disturbances and the other types of pain. After adjusting for motor symptom severity, pain intensity, anxiety, depression, and other factors, the odds of experiencing sleep disturbances continued to be higher in those with central parkinsonian pain (adjusted odds ratio, 2.46; 95% CI, 1.06-5.74; P = .037).
The study authors wrote that their results support previous findings on the association of sleep disturbances with pain symptoms and motor fluctuations in PD. These results also add to the literature by describing an association between sleep quality and pain that varies by pain subtype. They suggested that this relationship should be explored further in neuropsychological studies.
“A better understanding of the relationship between sleep disturbances and central parkinsonian pain may contribute to the development of new care strategies in PD patients,” they concluded.
Vila-Chã N, Cavaco S, Mendes A, et al. Sleep disturbances in Parkinson’s disease are associated with central parkinsonian pain. J Pain Res. 2019;12:2137-2144. doi: 10.2147/JPR.S206182.