Impact of pain and pain subtypes on the quality of life of patients with Parkinson’s disease

A Mixed Methods Approach to Explore the Experience of Pain and Its Management in People with Parkinson's Disease

Introduction

Pain in Parkinson's disease (PD) is common but poorly understood, with most research to date taking a mechanistic approach. This mixed methods study takes a broader biopsychosocial approach to assess and describe contributors of pain and explore pain management and the relationship between pain and physical activity in people with PD (PwPD) and chronic pain.

Methods

A structured survey evaluated respondents' contributors of pain using standardized, self-report assessments of the following: pain, peripheral neuropathy, central nociplastic change, emotional dysregulation or pathology, and maladaptive cognitions. Semistructured individual interviews were conducted with purposively sampled survey participants and analyzed using inductive thematic analysis.

Results

Eighty-nine PwPD (mean age 67 years, 55% female) completed the survey. The most common pain contributors were maladaptive cognitions (62%), central nociplastic change (49%), and emotional dysregulation (44%). Approaches to pain management and the response to physical activity were variable within and across individuals with different pain contributors. Four themes emerged from interviews with 24 participants: (1) causative perceptions of pain are diverse; (2) sense of control influences disease acceptance and exercise self-efficacy; (3) belief in the value of therapy; and (4) pain as the unspoken PD symptom. Physical activity was used by PwPD for pain management; however, the relationship between pain and physical activity varied based on sense of control.

Conclusions

Clinicians should screen for pain and assess its contributors to provide individualized, multidimensional pain management that considers the biological, psychological, and social factors of pain in PwPD. It is plausible that such an approach would promote a better sense of control for PwPD.

Safinamide for pain management in patients with Parkinson's disease

INTRODUCTION

Pain is often neglected in Parkinson's disease (PD), although it impacts most PD patients. While the mechanism of pain in PD is still being studied, various pharmacological, interventional, and alternative treatment options have been offered for pain relief. Safinamide, a recently approved drug for PD, has shown promising results in improving pain in patients with PD. Several clinical studies report changes in pain scores in PD patients treated with safinamide, but these have not been systematically summarized. Therefore, our main goal was to perform a systematic review and statistical analysis of relevant studies.

METHODS

A systematic search of studies was conducted using four databases: Pubmed, Cochrane Library, Google Scholar, and Scopus. The nine included randomized controlled trials did not provide sufficient data for a meta-analysis; therefore, we conducted a qualitative systematic review.

RESULTS

Our results suggest that safinamide at a daily dose of 100mg is more effective for treating PD pain than that of 50mg. Moreover, the reduction in fluctuation-related pain and pain from edema was more consistent when treated with safinamide compared to other PD pain types. We also attempted to suggest a mechanism of action for safinamide on pain processing in the brain, which should be explored in more detail in future studies.

CONCLUSION

Clinical evidence suggests that safinamide may be particularly beneficial for PD patients experiencing fluctuation-related pain and pain from edema, as these subtypes of pain showed greater improvement compared to other types of pain. Based on the findings of the included studies, safinamide appears to relieve the overall pain burden. However, the lack of sufficient data for conducting a meta-analysis highlights the need for future studies to report mean pain scores and their standard deviations.

Setting the clinical context to non-motor symptoms reflected by Park-pain, Park-sleep, and Park-autonomic subtypes of Parkinson's disease

Non-motor symptoms (NMS) of Parkinson's disease (PD) are well described in both clinical practice and the literature, enabling their management and enhancing our understanding of PD. NMS can dominate the clinical pictures and NMS subtypes have recently been proposed, initially based on clinical observations, and later confirmed in data driven analyses of large datasets and in biomarker-based studies. In this chapter, we provide an update on what is known about three common subtypes of NMS in PD. The pain (Park-pain), sleep dysfunction (Park-sleep), and autonomic dysfunction (Park-autonomic), providing an overview of their individual classification, clinical manifestation, pathophysiology, diagnosis, and potential treatments.

Analgesic effect of safinamide mesylate in a rat model of neuropathic pain

Pain is one of the most frequent non-motor symptoms of Parkinson's disease (PD). Neuropathic pain is highly prevalent in PD and negatively affects the quality of life of patients with PD. However, there is currently no evidence-based treatment for its control. Safinamide, a monoamine oxidase (MAO)-B inhibitor with a sodium channel inhibitory effect, showed improvement in PD-related pain in several clinical trials. However, it is unclear for which of the various types of pain in PD safinamide is effective. The aim of the present study was to examine the effect of safinamide on neuropathic pain in a rat model of chronic constriction injury (CCI). Pain was evaluated on postoperative days 14 and 21 using von Frey or weight-bearing tests. Male CCI model rats showed a decreased paw withdrawal threshold and a weight-bearing deficit on postoperative days 14 and 21. Single oral administration of safinamide (15, 30, 45 or 70 mg/kg) dose-dependently improved neuropathic pain in both pain assessments on day 14. Subsequently, the 15 and 45 mg/kg dose groups were administered safinamide orally once daily until day 21. With repeated administration, the effect of safinamide on pain was enhanced. The present findings show that safinamide improves neuropathic pain in male CCI model rats. Further animal model research and pathological and molecular pharmacological investigations are warranted.

Opicapone versus placebo in the treatment of Parkinson’s disease patients with end-of-dose motor fluctuation-associated pain: rationale and design of the randomised, double-blind OCEAN (OpiCapone Effect on motor fluctuations and pAiN) trial

Background

Optimisation of dopaminergic therapy may alleviate fluctuation-related pain in Parkinson’s disease (PD). Opicapone (OPC) is a third-generation, once-daily catechol-O-methyltransferase inhibitor shown to be generally well tolerated and efficacious in reducing OFF-time in two pivotal trials in patients with PD and end-of-dose motor fluctuations. The OpiCapone Effect on motor fluctuations and pAiN (OCEAN) trial aims to investigate the efficacy of OPC 50 mg in PD patients with end-of-dose motor fluctuations and associated pain, when administered as adjunctive therapy to existing treatment with levodopa/dopa decarboxylase inhibitor (DDCi).

Methods

OCEAN is a Phase IV, international, multicentre, randomised, double-blind, placebo-controlled, parallel-group, interventional trial in PD patients with end-of-dose motor fluctuations and associated pain. It consists of a 1-week screening period, 24-week double-blind treatment period and 2-week follow-up period. Eligible patients will be randomised 1:1 to OPC 50 mg or placebo once daily while continuing current treatment with levodopa/DDCi and other chronic, stable anti-PD and/or analgesic treatments. The primary efficacy endpoint is change from baseline in Domain 3 (fluctuation-related pain) of the King’s Parkinson’s disease Pain Scale (KPPS). The key secondary efficacy endpoint is change from baseline in Domain B (anxiety) of the Movement Disorder Society-sponsored Non-Motor rating Scale (MDS-NMS). Additional secondary efficacy assessments include other domains and total scores of the KPPS and MDS-NMS, the Parkinson’s Disease Questionnaire (PDQ-8), the MDS-sponsored Unified Parkinson’s Disease Rating Scale (MDS-UPDRS) Parts III and IV, Clinical and Patient’s Global Impressions of Change, and change in functional status via Hauser’s diary. Safety assessments include the incidence of treatment-emergent adverse events. The study will be conducted in approximately 140 patients from 50 clinical sites in Germany, Italy, Portugal, Spain and the United Kingdom. Recruitment started in February 2021 and the last patient is expected to complete the study by late 2022.

Discussion

The OCEAN trial will help determine whether the use of adjunctive OPC 50 mg treatment can improve fluctuation-associated pain in PD patients with end-of-dose motor fluctuations. The robust design of OCEAN will address the current lack of reliable evidence for dopaminergic-based therapy in the treatment of PD-associated pain.

Trial registration

EudraCT number 2020–001175-32; registered on 2020-08-07.

Evaluating the effects of dance on motor outcomes, non-motor outcomes, and quality of life in people living with Parkinson's: a feasibility study

BACKGROUND

Community-based dance programs for people living with Parkinson's have grown in popularity over the past two decades. Studies investigating these programs have demonstrated multidimensional benefits in motor, non-motor, and quality of life related outcomes, yet there is a need to focus on the feasibility of larger trials. The primary objective of this study was to assess the feasibility and acceptability of conducting a trial investigating dance and Parkinson's in Northern Ireland. The secondary objectives were to conduct preliminary analyses of the classes' effects and to assess the appropriateness of outcome measures for a randomized controlled trial.

METHODS

Participants were recruited through the community, Parkinson's UK, and university contacts to participate in a 12-week dance intervention inspired by the Dance for PD® model. Pre- and post-intervention, participants completed the following outcomes: MDS-UPDRS III, TUG, DT-TUG, Sensory Organization Test, MoCA, Trail Making Tests A&B, Digit Symbol Substitution Test, Digit Span, PDQ-39, FOG-Q, PHQ-9, FES-I, and an exit questionnaire (post-test only). Data were analyzed using paired samples t tests or Wilcoxon signed ranked test.

RESULTS

Ten people living with Parkinson's participated. Running a larger trial was deemed infeasible in this setting due to recruitment issues; conversely, the dance intervention was accepted by participants with all but one completing the study. Functional mobility (TUG), symptoms of depression (PHQ-9), and bodily discomfort showed improvement. All other outcomes did not. The exit questionnaire revealed that the social aspect of classes was important, and improvements in mood or mental state were cited most frequently as perceived benefits. Outcome measures were feasible, with some changes suggested for future trials.

CONCLUSIONS

This study highlighted the infeasibility of running a larger trial using this design in this setting despite demonstrating the acceptability of implementing a dance program in Northern Ireland for people living with Parkinson's. The results support existing evidence demonstrating that dance may improve functional mobility and symptoms of depression in people living with Parkinson's, though the study design and small sample size prevent the generalizability of results. The findings also support the idea that dancing has the potential to support several aspects of physical, emotional, mental, and social health.

Fluctuating pain in Parkinson's disease: Its prevalence and impact on quality of life

Pain is a common non-motor symptom in Parkinson's disease (PD) patients, and the incidence of fluctuating pain may be improved by taking levodopa. There are only a few detailed reports regarding fluctuating pain. In this study, 331 PD patients were classified into three groups: no-pain group (67.4%), non-fluctuating pain group (22.1%), and fluctuating pain group (10.6%). We evaluated patients' background and its impact on the quality of life (QOL) of each group. The pain group exhibited higher levels of depression (p < 0.0001), had a higher frequency of visual hallucinations (p = 0.007), and lower QOL (p < 0.0001) compared with the no-pain group. The fluctuating pain group had a younger onset (p = 0.006), higher Hoehn & Yahr stage (p = 0.018), and higher frequency of wearing-off (p < 0.001) and dyskinesia (p = 0.007) than the other groups. We compared the Parkinson's Disease Questionnaire-8 summary index (PDQ-8 SI) in each pain group to the no-pain group using analysis of variance. As a result, PDQ-8 SI was significantly higher in both the non-fluctuating and fluctuating pain groups (p < 0.0001). Pain is regarded as a non-negligible symptom that affects the QOL of PD patients, and given the unique characteristics, fluctuating pain might be considered as an independent clinical subtype of PD.

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Clinical characteristics of fluctuating pain in Parkinson's disease

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The prevalence of pain in PD was 10.6%, of which 32.4% showed fluctuating pain.

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Fluctuating pain is related to younger age of onset and severity of disease.

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Pain affects the quality of life of patients with Parkinson's disease.

Efficacy and safety evaluation of safinamide as an add-on treatment to levodopa for parkinson's disease

INTRODUCTION

While levodopa is still the most effective treatment for Parkinson's disease, concerns about long-term complications such as wearing-off and dyskinesia with levodopa usage remain.

AREAS COVERED

Safinamide is a highly selective and reversible monoamine oxidase B inhibitor introduced in the European Union, Japan, and the United States as an adjunctive agent to levodopa in PD patients with motor fluctuation. This review outlines the pharmacological properties, therapeutic effects, and tolerability of safinamide as an adjunct to levodopa in patients with advanced PD. Efficacy and safety findings from double-blind and placebo-controlled clinical trials for safinamide as an adjunct therapy to levodopa for PD are summarized.

EXPERT OPINION

Safinamide was well tolerated as a treatment for PD, and there was no significant difference in the frequency and severity of adverse events between the safinamide and placebo groups. It was also suggested that safinamide had a beneficial effect on the accompanying non-motor symptoms such as PD-related pain. Safinamide may exhibit neuroprotective effects through antioxidant and anti-glutamate effects, and research on the disease-modifying effect of PD is desired in the future.

Effects of safinamide adjunct therapy on pain in patients with Parkinson's disease: Post hoc analysis of a Japanese phase 2/3 study

INTRODUCTION

The non-dopaminergic and dopaminergic actions of safinamide may alleviate pain in patients with Parkinson's disease (PD). We investigated the efficacy of safinamide for pain when administered as an adjunct to levodopa in Japanese patients with PD.

METHODS

This was a post hoc analysis of a phase 2/3 clinical study of safinamide in Japanese patients with PD who were experiencing wearing-off. Pain was assessed using the Unified Parkinson's Disease Rating Scale (UPDRS) Part II 'sensory symptoms' item 17, on a scale of 0-4, and the 39-item Parkinson's Disease Questionnaire (PDQ-39) 'bodily discomfort' domain score. Subgroup analyses, according to baseline symptoms and concomitant medications, were also performed.

RESULTS

Least square (LS) mean changes in the UPDRS item 17 score from baseline to Week 24 in the placebo, safinamide 50-mg and safinamide 100-mg groups during the OFF phase were 0.08, -0.15 (p = 0.0133 vs placebo) and -0.18 (p = 0.0054), respectively, and during the ON phase were 0.04, -0.08 (p = 0.0529) and -0.08 (p = 0.0505), respectively. Changes from baseline to Week 24 in PDQ-39 'bodily discomfort' scores were not significantly different in safinamide groups vs placebo. The presence of moderate-to-severe bradykinesia or early-morning dystonia at baseline resulted in numerically greater effect sizes in UPDRS item 17 scores during the OFF phase.

CONCLUSIONS

Safinamide 50 mg and 100 mg reduced the UPDRS item 17 score in patients with PD, especially during the OFF phase. Patients with moderate-to-severe bradykinesia and early-morning dystonia may benefit from safinamide treatment.

The prevalence of pain in Huntington's disease in a large worldwide cohort

INTRODUCTION

Pain could be an unknown non-motor symptom in Huntington's Disease (HD). The aim is therefore, to study the prevalence of pain interference, painful conditions and analgesic use across the different stages of HD and compare these levels to non-HD gene mutation carriers.

METHODS

A cross-sectional analysis of the Enroll-HD study was conducted in premanifest, manifest HD gene mutation carriers (n = 3989 and n = 7,485, respectively) and in non-HD gene mutation carriers (n = 3719). To investigate group differences, multivariable logistic regression analysis was performed with pairwise comparisons.

RESULTS

In the HD mutation carriers, the overall prevalence of pain interference was 34% (95% CI 31%-35%), of painful conditions 17% (95% CI 15%-19%) and analgesic use 13% (95% CI 11%-15%). Compared to non-mutation carriers, the prevalence of pain interference was significantly higher in the middle stage of HD (33% [95% CI 31%-35%] vs 42% [95% CI 39%-45%], P = 0,02), whereas the prevalence of painful conditions was significant lower in the late and middle stage of HD (17% [95% CI 16%-18%] vs 12% [95% CI 10%-14%], 15% [95% CI 13%-17%], P < 0,01]. No significant group difference was present in analgesic use.

CONCLUSIONS

The prevalence of pain interference increases as HD progresses, however, the prevalence of painful conditions and analgesics do not increase accordingly. Further studies are necessary to investigate the aetiology of pain in HD and the risk for undertreatment of pain.

Evolution of Quality of Life in Persons with Parkinson's Disease: A Prospective Cohort Study

Parkinson's disease (PD) is a chronic neurodegenerative disorder that results in important functional symptoms, altered mood, and deterioration in quality of life (QoL). This study aimed to determine the evolution of the QoL in persons with PD in the Albacete health district over a two-year period and identify associated sociodemographic, clinical, and socio-health characteristics. A cohort study was conducted of patients at different stages of PD in the Albacete health district. Calculated sample size: 155 patients. Instruments: A purpose-designed questionnaire for data collection and the "Parkinson Disease Questionnaire" (PDQ-39), which measures 8 dimensions and a global index where a higher score indicates worse quality of life. Three measurements were made: baseline, one year, two years. A descriptive and bivariate analysis was conducted. Ethical aspects: informed consent, anonymized data. Results: Mean age 69.51 (standard deviation, SD 8.73) years, 60% male, 75.5% married, and 85.5% lived with family. The most frequent motor symptoms were slow movement (86.23%), postural instability (55.5%), tremor (45.5%), and dyskinesia (24.6%). Among the non-motor symptoms were fatigue (66.2%), pain, daytime somnolence, constipation, and apathy, with approximately 50% each. The mean QoL score at baseline was 27.47 (SD 16.14); 95% CI (confidence interval) 24.91-30.03. At two years, global QoL had slightly worsened (28.3; SD 17.26; 95% CI 25.41-31.18), with a statistically significant worsening in mobility, activities of daily living, and communication, whereas social support improved.

Health-Related Quality of Life for Parkinson's Disease Patients and Their Caregivers

Objective

Motor and non-motor symptoms (NMS) negatively impact the health-related quality of life (HRQoL) for individuals with Parkinson’s disease (PD), as well as their caregivers. NMS can emerge decades prior to the manifestation of motor symptoms but often go unrecognized and therefore untreated. To guide clinical management, we surveyed differences and identified factors that influence HRQoL in a cohort of PD patients and family caregivers.

Methods

A total of 103 PD patients were compared with 81 caregivers. Outcome measures collected from validated questionnaires included generic and disease-specific HRQoL assessments, depression frequency and severity, constipation severity, upper and lower gastrointestinal symptoms, physical activity and motor symptom severity.

Results

PD patients reported significantly decreased physical and mental HRQoL compared to their caregivers (both p < 0.001). Unemployment, the need for social support services, rehabilitation use, REM sleep behavior disorder, impulse control disorders and features suggestive of increasing disease severity hallmarked by increasing PD duration, higher MDS UPDRS-III (Movement Disorder Society–Unified Parkinson’s Disease Rating Scale–Part III) scores, higher daily levodopa equivalence dose and motor fluctuations were consistent with a lower HRQoL in our PD cohort. Furthermore, decreased physical activity, chronic pain, depression, constipation and upper gastrointestinal dysfunction (particularly indigestion, excess fullness and bloating) suggested vulnerability to reduced HRQoL. Overall, PD patients perceived their health to decline by 12% more than their caregivers did over a 1-year period.

Conclusion

PD patients reported decreased HRQoL, with both motor symptoms and NMS negatively impacting HRQoL. Our findings support the routine clinical screening of HRQoL in PD patients to identify and address modifiable factors.

Sheth M, Viswanath O, Urits I. Chronic Pain Treatment Strategies in Parkinson's Disease

Neurological disorders, including Parkinson's disease (PD), have increased in prevalence and are expected to further increase in the coming decades. In this regard, PD affects around 3% of the population by age 65 and up to 5% of people over the age of 85. PD is a widely described, physically and mentally disabling neurodegenerative disorder. One symptom often poorly recognized and under-treated by health care providers despite being reported as the most common non-motor symptom is the finding of chronic pain. Compared to the general population of similar age, PD patients suffer from a significantly higher level and prevalence of pain. The most common form of pain reported by Parkinson's patients is of musculoskeletal origin. One of the most used combination drugs for PD is Levodopa-Carbidopa, a dopamine precursor that is converted to dopamine by the action of a naturally occurring enzyme called DOPA decarboxylase. Pramipexole, a D2 dopamine agonist, and apomorphine, a dopamine agonist, and Rotigotine, a dopamine receptor agonist, have showed efficacy on PD-associated pain. Other treatments that have shown efficacy in treating pain of diverse etiologies are acetaminophen, Nonsteroidal anti-inflammatory drugs (NSAIDs), and cyclooxygenase-2 (COX-2) inhibitors. Opioids and opioid-like medications such as oxycodone, morphine, tramadol, and codeine are also commonly employed in treatment of chronic pain in PD. Other opioid related medications such as Tapentadol, a central-acting oral analgesic with combined opioid and noradrenergic properties, and Targinact, a combination of the opioid agonist oxycodone and the opioid antagonist naloxone have shown improvement in pain. Anticonvulsants such as gabapentin, pregabalin, lamotrigine, carbamazepine and tricyclic antidepressants (TCAs) can be trialed when attempting to manage chronic pain in PD. The selective serotonin and noradrenaline reuptake inhibitors (SNRIs) also possess pain relieving and antidepressant properties, but carry less of the risk of anticholinergic side effects seen in TCAs. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) has been shown in multiple studies to be effective against various types of PD associated pain symptoms. Massage therapy (MT) is one of the most common forms of complementary and alternative medicine. Studies have shown that pressure applied during MT may stimulate vagal activity, promoting reduced anxiety and pain, as well as increasing levels of serotonin. In a survey study of PD patients, rehabilitative therapy and physical therapy were rated as the most effective for pain reduction, though with only temporary relief but these studies were uncontrolled. Yoga has been studied for patients with a wide array of neurological disorders. In summary, PD pathology is thought to have a modulating effect on pain sensation, which could amplify pain. This could help explain a portion of the higher incidence of chronic pain felt by PD patients. A treatment plan can be devised that may include dopaminergic agents, acetaminophen, NSAIDs, opioids, antidepressants, physical therapies, DBS and other options discussed in this review. A thorough assessment of patient history and physical examination should be made in patients with PD so chronic pain may be managed effectively.

Low back pain in Parkinson's disease: A cross-sectional study of its prevalence, and implications on functional capacity and quality of life

OBJECTIVE

The aim of this study was to estimate the prevalence of low back pain (LBP) in patients with Parkinson's disease (PD) and its impact on functional capacity and quality of life.

METHODS

Patients with idiopathic PD answered a questionnaire and were submitted to a clinical and functional assessment. Unified Parkinson's Disease Rating Scale (UPDRS), Hoehn and Yahr Scale, Beck Depression Inventory (BDI), McGill Pain Questionnaire (McGill), Roland Morris Disability Questionnaire (RMDQ), 39-item Parkinson's Disease Questionnaire (PDQ-39) were used. In addition, the ability to contract transversus abdominis (TrA) was assessed.

RESULTS

One hundred and fifteen patients answered the questionnaire, and 95 (82.6 %) reported painful symptoms. Of these, 67 (58.3 %) had chronic LBP, and approximately 40 % patients reported its onset before diagnosis of PD. Higher scores in pain intensity, depressive symptoms and UPDRS II and III, more advanced stages of PD, and absence of TrA contraction determined poor functional limitation induced by LBP. However, pain intensity (McGill), severity of PD symptoms (UPDRS III) and absence of TrA contraction were identified as predictive factors for functional limitation and explained 66.1 % of the variance in the RMDQ. Pain intensity and LBP-related disability caused negative impact on the quality of life.

CONCLUSION

LBP is common in patients with PD and it causes disability and poor quality of life. Pain intensity, UPDRS III and absence of TrA contraction were the most significant predictive factors for disability assessed by the RMDQ.

An overview of pain in Parkinson's disease

Pain is a common non-motor symptom of Parkinson's disease (PD) and the prevalence of pain among PD patients varies because of the disease stage, co-morbidities, and evaluating tools. Risk factors for pain in PD include an early age of onset, long disease duration, motor complications, concomitant depressive symptoms, female gender, and associated medical conditions. In patients with PD, pain can be classified as musculoskeletal pain, chronic body pain (central or visceral), fluctuation-related pain, nocturnal pain, orofacial pain, pain with discolouration/oedema/swelling, and radicular/neuropathic pain; musculoskeletal pain as the most common type. Potential underlying mechanisms include a disruption of peripheral nociception and alterations in central pain threshold/processing. Genetic polymorphisms in genes that confer pain susceptibility might also play a role in the occurrence of pain in PD. In advanced stage of patients with PD, polyneuropathy could occur in patients using high dosage of levodopa. Pain often correlates to other non-motor symptoms of PD, including depression, sleep, and autonomic symptoms. Dopaminergic drugs, non-dopaminergic medications, botulinum toxin, deep brain stimulation, and physiotherapy have shown some benefits for certain types of PD-related pain. An increased awareness of pain as a common non-motor symptom of PD provides further insights into sensory system dysregulation in this disease. In this review, we aim to summarizes the clinical features of pain in patients with PD and emphasize the latest evidence of pain related to levodopa treatment.

Dynamic Functional Connectivity and Symptoms of Parkinson's Disease: A Resting-State fMRI Study

Research has shown that dynamic functional connectivity (dFC) in Parkinson’s disease (PD) is associated with better attention performance and with motor symptom severity. In the current study, we aimed to investigate dFC of both the default mode network (DMN) and the frontoparietal network (FPN) as neural correlates of cognitive functioning in patients with PD. Additionally, we investigated pain and motor problems as symptoms of PD in relation to dFC. Twenty-four PD patients and 27 healthy controls participated in this study. Memory and executive functioning were assessed with neuropsychological tests. Pain was assessed with the Numeric Rating Scale (NRS); motor symptom severity was assessed with the Unified Parkinson’s Disease Rating Scale (UPDRS). All subjects underwent resting-state functional magnetic resonance imaging (fMRI), from which dFC was defined by calculating the variability of functional connectivity over a number of sliding windows within each scan. dFC of both the DMN and FPN with the rest of the brain was calculated. Patients performed worse on tests of visuospatial memory, verbal memory and working memory. No difference existed between groups regarding dFC of the DMN nor the FPN with the rest of the brain. A positive correlation existed between dFC of the DMN and visuospatial memory. Our results suggest that dynamics during the resting state are a neural correlate of visuospatial memory in PD patients. Furthermore, we suggest that brain dynamics of the DMN, as measured with dFC, could be a phenomenon specifically linked to cognitive functioning in PD, but not to other symptoms.

Relationship of Nocturnal Sleep Dysfunction and Pain Subtypes in Parkinson's Disease

Background

Little research has been conducted regarding the relationship between sleep disorders and different pain types in Parkinson's disease (PD).

Objective

To explore the influence of the various pain subtypes experienced by PD patients on sleep.

Methods

Three hundred consecutive PD patients were assessed with the PD Sleep Scale-Version 2 (PDSS-2), King's PD Pain Scale (KPPS), King's PD Pain Questionnaire (KPPQ), Visual Analog Scales for Pain (VAS-Pain), and Hospital Anxiety and Depression Scale.

Results

According to the PDSS-2, 99.3% of our sample suffered from at least one sleep issue. Those who reported experiencing any modality of pain suffered significantly more from sleep disorders than those who did not (all, P < 0.003). The PDSS-2 showed moderate-to-high correlations with the KPPS (r_S = 0.57), KPPQ (0.57), and VAS-Pain (0.35). When PDSS-2 items 10 to 12 (pain-related) were excluded, the correlation values decreased to 0.50, 0.51, and 0.28, respectively, while these items showed moderate-to-high correlations with KPPS (0.56), KPPQ (0.54), and VAS-Pain (0.42). Among the variables analyzed, multiple linear regression models suggested that KPPS and KPPQ were the most relevant predictors of sleep disorders (as per the PDSS-2), although following exclusion of PDSS-2 pain items, depression was the relevant predictor. Depression and anxiety were the most relevant predictors in the analysis involving the VAS-Pain. Regression analysis, considering only the KPPS domains, showed that nocturnal and musculoskeletal pains were the best predictors of overall nocturnal sleep disorder.

Conclusions

Pain showed a moderate association with nocturnal sleep dysfunction in PD. Some pain subtypes had a greater effect on sleep than others.

Peripheral neuropathic pain in idiopathic Parkinson's disease: Prevalence and impact on quality of life; a case controlled study

BACKGROUND AND PURPOSE

Pain is a frequent and debilitating non-motor symptom of Idiopathic Parkinson's Disease (IPD). The present study investigated the prevalence of pain and specifically peripheral neuropathic pain (PNP) in IPD, and ascertained any impact of PNP on quality of life (QoL).

METHODS

Patients with IPD and age- and gender-matched controls were screened for overall pain using the King's Parkinson's Pain Scale (KPPS). PNP was assessed using the Michigan Neuropathy Screening Instrument (MNSI). QoL was assessed using the 36-Item Short Form Survey (SF-36).

RESULTS

Fifty-one patients and 51 age and gender matched controls were recruited. The prevalence of overall pain was similar in the two groups (88.2% versus 94.1%, p = 0.487). However, patients with IPD had higher KPPS scores in fluctuation-related (4.9 ± 6.9 vs 1.1 ± 2.6, p < 0.001), nocturnal (6.6 ± 7.5 vs 1.7 ± 4.2, p < 0.001) and oro-facial (0.6 ± 2.0 vs 0.0 ± 0.0, p = 0.040) domains compared to controls. Patients with IPD experienced more PNP compared to healthy control subjects (35.3% versus 13.7%, p = 0.011). After adjusting for age, gender, disease duration and overall KPSS score, PNP correlated negatively with physical functioning score (beta -0.290, p = 0.036), emotional role limitations score (beta -0.319, p = 0.032) and general health perception score (beta -0.342, p = 0.014) domains of SF-36.

CONCLUSION

Peripheral neuropathic pain is prevalent in IPD and has a significant impact on QoL. The presence of burning pain is suggestive of small fibre neuropathy, but this symptom is not featured in KPSS and, therefore, a revision of the KPSS should be considered.