Pain in Parkinson disease: a deep phenotyping study

ABSTRACT

In our prospective cross-sectional study, we comprehensively characterized Parkinson disease (PD)-related pain in monocentrically recruited patients with PD using standardized tools of pain assessment and categorization. One hundred fifty patients were systematically interviewed and filled in questionnaires for pain, depression, motor, and nonmotor symptoms. Patients with PD-related pain (PD pain), patients without PD-related pain (no PD pain), and patients without pain (no pain) were compared. Pain was present in 108/150 (72%) patients with PD, and 90/150 (60%) patients were classified as having PD-related pain. Most of the patients with PD (67/90, 74%) reported nociceptive pain, which was episodic (64/90, 71%), primarily nocturnal (56/90, 62%), and manifested as cramps (32/90, 36%). Parkinson disease-related pain was most frequently located in the feet (51/90, 57%), mainly at the toe joints (22/51, 43%). 38/90 (42%) patients with PD-related pain received analgesic medication with nonsteroidal anti-inflammatory drugs being the most frequently used (31/42, 82%) and opioids most effective (70% pain reduction of individual maximum pain intensities, range 22%-100%, confidence interval 50%-90%). All patients received oral PD treatment; however, levodopa equivalent dose showed no correlation with mean pain intensities (Spearman ρ = 0.027, P > 0.05). Our data provide a comprehensive analysis of PD-related pain, giving evidence for mainly non-neuropathic podalgia, which bears the potential to rethink assessment and analgesic treatment of pain in PD in clinical practice.

Prevalence of radicular neuropathic pain in idiopathic Parkinson's disease: a systematic review and meta-analysis

Parkinson's disease (PD) is estimated to impact up to 1% of the global population aged 60 years and older. Among the non-motor manifestations of idiopathic PD, radicular neuropathic pain emerges as a noteworthy concern due to its potential for debility in affected individuals. In, this systematic review and meta-analysis we aimed to evaluate the prevalence of radicular neuropathic pain and thus provide evidence of how this painful symptom affects the lives of patients with idiopathic PD. We registered the research protocol for this study in PROSPERO (CRD42022327220). We searched the Embase, Scopus, and PubMed platforms for studies on PD and neuropathic pain until April 2023. The search yielded 36 articles considered to have a low risk of bias. The prevalence of radicular neuropathic pain in patients with PD was 12.7%, without a difference when we consider the duration of diagnosis (cut-off < 7 years) or levodopa dosage (cut-off <600mg/dL). Moreover, there was no variation in the prevalence of radicular neuropathic pain regarding a Hoehn and Yahr stage cut-off of <2.5 or >2.5. Of note, a limited number of patients received pain treatment (21.5%). We also found that the source of publication bias is the use of the Ford criteria (FC), suggesting that this type of diagnostic criteria may contribute to an underdiagnosis of radicular neuropathic pain in patients with PD. This study underlines the necessity for a more discerning and comprehensive approach to the diagnosis and management of radicular neuropathic pain in patients with idiopathic PD.

Pathological pain: Non-motor manifestations in Parkinson disease and its treatment

In addition to motor symptoms, non-motor manifestations of Parkinson's disease (PD), i.e. pain, depression, sleep disturbance, and autonomic disorders, have received increasing attention. As one of the non-motor symptoms, pain has a high prevalence and is considered an early pre-motor symptom in the development of PD. In relation to pathological pain and its management in PD, particularly in the early stages, it is hypothesized that the loss of dopaminergic neurons causes a functional deficit in supraspinal structures, leading to an imbalance in endogenous descending modulation. Deficits in dopaminergic-dependent pathways also affect non-dopaminergic neurotransmitter systems that contribute to the pathological processing of nociceptive input, the integration, and modulation of pain in PD. This review examines the onset and progression of pain in PD, with a particular focus on alterations in the central modulation of nociception. The discussion highlights the importance of abnormal endogenous descending facilitation and inhibition in PD pain, which may provide potential clues to a better understanding of the nature of pathological pain and its effective clinical management.

TDCS for parkinson's disease disease-related pain: A randomized trial

OBJECTIVE

To evaluate the effects of transcranial direct current stimulation (tDCS) on Parkinson's disease (PD)-related pain.

METHODS

This triple-blind randomized controlled trial included twenty-two patients (age range 38-85, 10 male) with PD-related pain. Eleven subjects received ten sessions of 20 minutes tDCS over the primary motor cortex contralateral to pain at 2 mA intensity. Eleven subjects received sham stimulation. Outcome measures included changes in the Kinǵs Parkinsońs Pain Scale (KPPS), Brief Pain Inventory (BPI), widespread mechanical hyperalgesia (WMH), temporal summation of pain (TS), and conditioned pain modulation (CPM).

RESULTS

Significant differences were found in KPPS between groups favoring the active-tDCS group compared to the sham-tDCS group at 15-days follow-up (p = 0.014) but not at 2 days post-intervention (p = 0.059). The active-group showed significant improvements over the sham-group after 15 days (p = 0.017). Significant changes were found in CPM between groups in favor of active-tDCS group at 2 days post-intervention (p = 0.002) and at 15 days (p = 0.017). No meaningful differences were observed in BPI or TS.

CONCLUSIONS

tDCS of the primary motor cortex alleviates perceived PD-related pain, reduces pain sensitization, and enhances descending pain inhibition.

SIGNIFICANCE

This is the first study to test and demonstrate the use of tDCS for improving PD-related pain.

The Impact of Fatigue on Sleep and Other Non-Motor Symptoms in Parkinson's Disease

Fatigue is a common non-motor symptom in Parkinson's disease (PD), but even so, it may still be underdiagnosed or misdiagnosed in current practice due to its non-specific manifestations. The aims of this study were to investigate the prevalence of fatigue in PD patients compared to healthy controls and to identify the main characteristics and associations of fatigue with other non-motor symptoms and the impact of fatigue on sleep disturbances in Parkinson's disease.

MATERIALS AND METHODS

case-control study in which 131 PD patients and 131 age- and sex-matched controls were enrolled. Main characteristics of fatigue, sleep, and other non-motor symptoms were assessed using specific validated questionnaires.

RESULTS

According to the Chalder fatigue scale, fatigue is more prevalent in PD patients (38.16%) compared to healthy controls (26.71%). Fatigue was identified in 46.54% of the PD patients using the Parkinson's Fatigue Scale (PFS-16). PD patients with fatigue presented a worse motor status, more sleep disturbances (insomnia, daytime sleepiness), a broader spectrum of non-motor symptoms (pain, anxiety, urinary disturbances), worse cognitive performances, a lower level of happiness, and worse quality of life compared to PD patients without fatigue.

CONCLUSION

Fatigue is a common symptom of PD and needs to be assessed, considering its consequences on quality of life. Sleep disturbances have a great influence over fatigue in PD patients.

Translation, cultural adaptation and validation of the Arabic version of the king's Parkinson's disease pain scale

PURPOSE

Pain in Parkinson's disease (PD) is a highly prevalent non-motor symptom occurring in this population. The King's PD Pain Scale (KPPS) was developed to assess pain in people with PD. This study aimed to provide a cross-cultural adaptation and translation of the KPPS into the Arabic language (A-KPPS), and to investigate the construct and convergent validity, internal consistency, and reliability of the translated scale.

MATERIALS AND METHODS

The English KPPS was translated into Arabic and back-translated into English by an independent translation team. The Arabic version was tested in 103 native Arabic speaking PD patients. We assessed construct validity, convergent validity, and test-retest reliability of the A-KPPS using factor analysis method, comparison with other valid and reliable measures, and using intra-class correlations, respectively.

RESULTS

The A-KPPS had three main factors "somatic pain", "visceral and burning pain" and "orofacial pain", rather than the original four factors scale. The A-KPPS correlated with measures of disease motor severity, depression, anxiety, quality of life and pain (p < 0.05). Furthermore, the A-KPPS total score had high test-retest reliability (ICC = 0.9).

CONCLUSIONS

The A-KPPS demonstrated moderate to good validity and reliability. The A-KPPS can facilitate the assessment and treatment of pain in Arabic-speaking people with PD worldwide.

Dyskinesia and Pain in Advanced Parkinson's Disease: Post Hoc Analysis from the Phase 3b, Open-Label, Randomized DYSCOVER Study

INTRODUCTION

The DYSCOVER study was a phase 3b, open-label, randomized trial (NCT02799381) that evaluated levodopa-carbidopa intestinal gel (LCIG) versus optimized medical treatment (OMT) in patients with Parkinson's disease (PD) and a high burden of dyskinesia at baseline (defined as Unified Dyskinesia Rating Scale [UDysRS] total score ≥ 30). At week 12, patients receiving LCIG versus OMT experienced significant improvements in dyskinesia, pain, and health-related outcomes. The objective of this analysis was to examine correlations between dyskinesia, pain, and health-related outcomes in PD.

METHODS

This post hoc analysis assessed correlations between UDysRS, King's Parkinson's Disease Pain Scale (KPPS), 8-item Parkinson's Disease Questionnaire (PDQ-8), Unified Parkinson's Disease Rating Scale part II, Clinical Global Impression of Severity (CGI-S) or Change (CGI-C), and "On" time without troublesome dyskinesia at baseline and after 12 weeks of LCIG or OMT. Correlations were assessed by Pearson correlation coefficients (categorization: weak, r = 0.20-0.39; moderate, r = 0.40-0.59; strong, r ≥ 0.60).

RESULTS

Among 61 patients, moderate-to-strong positive and significant correlations were observed between UDysRS and KPPS scores (baseline, r = 0.47; week 12 change from baseline [CFB], r = 0.63; all p < 0.001). UDysRS and KPPS scores had moderate-to-strong positive and highly significant correlations with PDQ-8 scores (baseline, r = 0.45 and 0.46, respectively; CFB, r = 0.54 and 0.64, respectively; all p < 0.001). Moderate positive and significant correlations were observed between UDysRS and CGI-S/CGI-C scores (baseline, r = 0.41; CFB, r = 0.47; all p < 0.001).

CONCLUSIONS

In patients with high dyskinesia burden, positive correlations were observed between dyskinesia, pain, and health-related quality of life (HRQoL) at baseline. Improvements in dyskinesia and pain were associated with improvements in HRQoL, demonstrating the clinical burden of troublesome dyskinesia.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov identifier NCT02799381.

Pain and the Non-Pharmacological Management of Pain in People with Parkinson's Disease

Pain is a distressing and universal experience, yet everyone's pain experience is influenced by a complex array of biological, psychological, and social factors. For people with Parkinson's disease (PwP), these biopsychosocial factors include neurodegeneration and the psychological and social factors that accompany living with a chronic, neurodegenerative condition in addition to the factors experienced by those in the general population (e.g., living with co-morbidities such as osteoarthritis). The way these factors influence each individual is likely to determine which pain management strategies are optimal for them. This review first describes pain and the biopsychosocial model of pain. It explores how pain is classified in Parkinson's disease (PD) and describes the three main types of pain: nociceptive, neuropathic, and nociplastic pain. This background provides context for a discussion of non-pharmacological pain management strategies that may aid in the management of pain in PwP; exercise, psychological strategies, acupuncture and massage. While there is little PD-specific research to inform the non-pharmacological management of pain, findings from current PD research are combined with that from chronic pain research to present recommendations for clinical practice. Recommendations include assessment that incorporates potential biopsychosocial contributors to pain that will then guide a holistic, multi-modal approach to management. As exercise provides overall benefits for PwP, those with chronic pain should be carefully monitored with exercise prescribed and adjusted accordingly. Research is needed to develop and evaluate multi-modal approaches to pain management that are delivered in a biopsychosocial framework.

Statistical analysis and generative Artificial Intelligence (AI) for assessing pain experience, pain-induced disability, and quality of life in Parkinson's disease patients

The Parkinson's Disease (PD) is a chronic neurodegenerative condition characterized by motor symptoms such as tremors, rigidity, and bradykinesia, which can significantly impact various aspects of daily life. Among these aspects, pain is a prominent element. Despite the widespread use of therapies aimed at improving symptoms and quality of life, effective pain management is essential to enhance the quality of life of individuals affected by this disease. However, a detailed understanding of the factors associated with pain in PD is still evolving. In this study, we examined the disability caused by pain and the pain experienced by PD patients using two validated questionnaires, namely the Parkinson's Disease Questionnaire (PDQ) and the King's Parkinson's Disease Pain Questionnaire (KPPQ). Customized questions were also included to further explore the pain experience and management strategies adopted by PD patients. Through statistical analysis, we explored the relationships between questionnaire scores, socio-demographic data, and other relevant variables. Additionally, generative Artificial Intelligence (AI) was employed to gain a deeper understanding of patient responses. The results indicate the extent and impact of pain in PD and provide valuable insights for more targeted and personalized management. This study lays the foundation for future research and the development of interventions aimed at improving the quality of life for individuals affected by this condition.

Validation study of the Japanese version of the King's Parkinson's Disease Pain Scale and the King's Parkinson's Disease Pain Questionnaire

INTRODUCTION

The King's Parkinson's Disease Pain Scale (KPPS)/King's Parkinson's Disease Pain Questionnaire (KPPQ) was developed as a tool to quantitatively assess pain in patients with Parkinson's disease (PwPD). Here, we conducted a Japanese multicenter validation study to verify the reliability of KPPS/KPPQ in Japanese PwPD.

METHODS

PwPD, ≥20 years, with unexplained pain were included; those with a definitive primary cause of pain other than PD were excluded. A total of 151 patients who fulfilled the criteria were analyzed, and test-retest reliability was investigated in 25 individuals.

RESULTS

The 151 patients included 101 women (66.9 %); mean age 68.3 ± 9.9 years, mean disease duration 9.2 ± 5.2 years. The most frequent pain type in the KPPS classification was musculoskeletal pain (82.8 %). There was a positive correlation between KPPS total score and the Non-Motor Symptoms Scale (NMSS) total score, NMSS item 27, the Parkinson's disease sleep scale-version 2 (PDSS-2) total score, PDSS-2 item 10, the Parkinson's Disease Questionnaire-8 (PDQ-8) summary index and PDQ-8 item 7. Cronbach's alpha of KPPS was 0.626 (0.562-0.658) and the intraclass correlation coefficient of test-retest reliability was 0.740. Cronbach's alpha of KPPQ was 0.660 (0.617-0.705) and a test-retest reliability of kappa coefficient was 0.593 (0.0-1.0).

CONCLUSIONS

KPPS correlated well with other scales for assessing pain. KPPS correlated well with patients' quality of life, non-motor symptoms, and sleep disturbances. The reproducibility of KPPS/KPPQ makes it suitable for continuous evaluation of the same patient. On the other hand, the internal consistency of KPPS/KPPQ is rather low.

CT-optimal touch and chronic pain experience in Parkinson's Disease; An intervention study

One of the most underdiagnosed and undertreated non-motor symptoms of Parkinson's Disease is chronic pain. This is generally treated with analgesics which is not always effective and can cause several side-effects. Therefore, new ways to reduce chronic pain are needed. Several experimental studies show that CT-optimal touch can reduce acute pain. However, little is known about the effect of CT-optimal touch on chronic pain. The aim of the current study is to investigate whether CT-optimal touch can reduce the chronic pain experience in Parkinson patients. In this intervention study, 17 Parkinson patients underwent three conditions; no touch, CT-optimal touch and CT non-optimal touch with a duration of one week each. During each touch week, participants received touch from their partners twice a day for 15 minutes. Results show that both types of touch ameliorate the chronic pain experience. Furthermore, it appears that it is slightly more beneficial to apply CT-optimal touch also because it is perceived as more pleasant. Therefore, we argue that CT-optimal touch might be used when immediate pain relief is needed. Importantly, this study shows that CT-optimal touch can reduce chronic pain in Parkinson's Disease and can be administered by a partner which makes it feasible to implement CT-optimal touch as daily routine.

Translation and cross-cultural adaptation of the Spanish version of the King's Parkinson's Disease Pain Scale (KPPS)

PURPOSE

To translate and cross-culturally adapt the King's Parkinson's Disease Pain Scale (KPPS) into Spanish.

METHODS

The English KPPS was forward translated into Spanish, back translated, and revised by the original developers. Cross-cultural adaptation of relevant target groups was conducted following COSMIN standards. Cognitive pretesting in Spanish people with Parkinson's Disease (PD) and pain was performed via three semi-structured focus group meetings. Changes were implemented based on qualitative and quantitative analyses. A Delphi study (two rounds) of individual assessments by Spanish experts was conducted. Changes were implemented based on the Content Validity Index (CVI) at item and scale levels (I-CVI/S-CVI).

RESULTS

Five Spanish professionals performed the initial translation. Thirty-eight inter-translation inconsistencies were identified, and consensus was reached for a unified version. After back translation and confirmation with scale developers, the pre-final Spanish KPPS was obtained. Cognitive pretesting in 30 people with PD-related pain identified 5 items where terminology changes were made to assure comprehensibility. The Delphi study in 14 Spanish experts underlined the necessity to further modify two items. After the second round, all experts agreed on the modifications and I-CVI and S-CVI were satisfactory.

CONCLUSIONS

The KPPS was successfully translated and cross-culturally adapted into Spanish.

Constipation and pain in Parkinson's disease: a clinical analysis

Parkinson's Disease (PD) is a neurodegenerative disorder characterized by both motor and non-motor symptoms (NMS). Among NMS, constipation and pain are both highly prevalent and debilitating affecting up to 80% of PD patients and impairing their quality of life. Here, we investigated the relationship between constipation and pain in PD patients. This is a retrospective study assessing the relationship between pain and constipation in a PD patient population from a clinical database of patients attending the outpatient clinic of the movement disorders division, Neurology Unit of Policlinico Tor Vergata, in Rome. Subjects were assessed with the Unified Parkinson's Disease Rating Scale (UPDRS) part III, Hoehn and Yahr (H&Y) stage, King's Parkinson's Disease Pain Scale (KPPS), Brief Pain Inventory (BPI), Non-Motor Symptoms Scale (NMSS) and Beck Depression Inventory (BDI). Patients were further divided in two groups (Group 1, 32 patients with constipation and Group 2, 35 PD patients without constipation) ANOVA and ANCOVA analysis were used to compare the two groups. PD patients with constipation had significantly higher pain severity and pain interference, as measured by the BPI scale and higher total KPPS score, fluctuation-related pain, nocturnal pain, and radicular pain when compared to PD patients without constipation. This study highlights for the first time a possible interplay between constipation and pain in PD that deserves further investigations.

Musculoskeletal pain in Parkinson's disease: Association with dopaminergic deficiency in the caudate nucleus

BACKGROUND

Musculoskeletal (MSK) pain affects over 80% of People with Parkinson's (PD, PwP) and may, in part, be dopaminergic in origin, as dopaminergic medication often leads to its relief.

METHODS

PwP who underwent striatal dopamine transporter visualization with a radiopharmaceutical DaTscan™ (123 I-Ioflupane Injection) using a single-photon emission computed tomography (SPECT) as a part of their clinical-diagnostic work up were enrolled in the "Non-motor International Longitudinal Study" (NILS; UK National Institute for Health Research Clinical Research Network Number 10084) and included in this cross-sectional analysis. The association between specific DaTscan binding ratios for each striatum, the caudate nucleus and putamen and clinical ratings for MSK pain (assessed using the King's Parkinson's Disease Pain Scale (KPPS)) were analysed.

RESULTS

53 PwP (30.2% female; age: 63.79 ± 11.31 years; disease duration (DD): 3.32 (0.31-14.41) years; Hoehn & Yahr stage (H&Y): 2 (1-4); Levodopa Equivalent Daily Dose (LEDD): 543.08 ± 308.94 mg) were assessed and included in this analysis. MSK pain was highly prevalent (71.7% of all participants, mean KPPS Item 1 score 5.34 ± 4.76) and did not correlate with the motor symptoms burden (SCOPA-Motor total score; p = 0.783) but showed a significant correlation with quality of life (PDQ-8, rs  = 0.290, p = 0.035). z-scores for the caudate nucleus (Exp (B) = 0.367, 95% CI for Exp (B) 0.148-0.910, p = 0.031) and striatum (Exp (B) = 0.338, 95% CI for Exp (B) 0.123-0.931, p = 0.036), adjusted for DD, H&Y and LEDD, were significant determinants of MSK pain.

CONCLUSIONS

Our findings suggest an association between MSK pain in PwP and the severity of dopaminergic deficiency in the caudate nucleus.

SIGNIFICANCE

In People with Parkinson's, musculoskeletal pain does not arise simply as a direct sequel to motor symptoms-instead, it is linked to the severity of dopaminergic depletion in the caudate nucleus.

The PD-Ballet study: study protocol for a randomised controlled single-blind hybrid type 2 clinical trial evaluating the effects of ballet dancing on motor and non-motor symptoms in Parkinson's disease

BACKGROUND

To date, beneficial effects of multimodal exercise programmes on Parkinson's disease (PD) have focused on motor symptoms and little attention has been paid to the potential effects of such programmes on the non-motor symptoms of PD, which are now universally known as one of the key drivers of quality of life and a key unmet need. We aim to explore clinical effectiveness of a ballet-based dance programme in addressing non-motor and motor symptoms of Parkinson's disease across all stages of progression.

METHODS

A randomised, single-blind, controlled trial of 160 people with Parkinson's across all motor stages (Participants will be stratified into three groups of motor advancement: Hoehn and Yahr (HY) stages I and II being Mild Group, HY Stage III being Moderate Group and HY Stages IV and V being Severe Group) will be randomly allocated to either an intervention or a control group using an independent randomisation body. The primary outcome is an improvement in non-motor symptoms as measured by the Movement Disorders Society Non-Motor Scale (MDS-NMS). The intervention protocol consists of 12 one-weekly dance sessions led by English National Ballet. Each session is followed by a 'tea and biscuit' social time. Control group follows standard clinical pathway and joins the 'tea and biscuit' to control for any positive effects of social interactions. All participants are assessed at baseline, immediately after completion of the intervention and 3-6 months later to explore any potential longitudinal effects.

DISCUSSION

To our knowledge, no adequately powered study has explored the effects of a dance-based intervention on non-motor symptoms of Parkinson's disease, assessing these on both holistic and granular levels. We also aim to stratify participants in accordance with their motor state as assessed by. HY staging to explore specific effects on the symptoms at the initial, moderate and complex stages of the disease. If successful, this trial provides first evidence on clinical effectiveness of a ballet-based dance intervention for symptoms of Parkinson's disease, assessed in a robust, rigorous manner.

TRIAL REGISTRATION

NCT04719468.

Effects of deep brain stimulation and verbal suggestions on pain in Parkinson's disease

BACKGROUND AND OBJECTIVES

In Parkinson's disease (PD) patients, verbal suggestions have been shown to modulate motor and clinical outcomes in treatment with subthalamic deep brain stimulation (DBS). Furthermore, DBS may alleviate pain in PD. However, it is unknown if verbal suggestions influence DBS' effects on pain.

METHODS

Twenty-four people with PD and DBS had stimulation downregulated (80-60 to 20%) and upregulated (from 20-60 to 80%) in a blinded manner on randomized test days: (1) with negative and positive suggestions of pain for down- and upregulation, respectively, and (2) with no suggestions to effect (control). Effects of DBS and verbal suggestions were assessed on ongoing and evoked pain (hypertonic saline injections) via 0-10 numerical rating scales along with motor symptoms, expectations, and blinding.

RESULTS

Stimulation did not influence ongoing and evoked pain but influenced motor symptoms in the expected direction. Baseline and experimental pain measures showed no patterns in degree of pain. There was a trend toward negative suggestions increasing pain and positive suggestions decreasing pain. Results show significant differences in identical stimulation with negative vs positive suggestions (60% conditions AUC 38.75 vs 23.32, t(13) = 3.10, p < 0.001). Expectations to pain had small to moderate effects on evoked pain. Patients estimated stimulation level correctly within 10 points.

CONCLUSION

Stimulation does not seem to influence ongoing and evoked pain, but verbal suggestions may influence pain levels. Patients appear to be unblinded to stimulation level which is an important consideration for future studies testing DBS in an attempted blind fashion.

Pain is common in early onset Parkinson's disease and pain severity is associated with age and worsening of motor and non-motor symptoms

The consequences of pain in early onset Parkinson's disease (EOPD) remain under appreciated even though pain may exert an increasingly negative impact on patient quality of life as motor and non-motor symptoms worsen. In this prospective study, we investigate the prevalence and severity of pain in 135 Vietnamese patients with EOPD from three medical centers using the King's PD Pain Scale (KPPS), the Mini Mental Status Exam (MMSE), the Unified Parkinson's Disease Rating Scale (UPDRS) and the Non-Motor Symptoms Scale (NMSS). Pain was reported by 79.3%. The most common subtype of pain was musculoskeletal (70.1%), followed by nocturnal (43.9%), radicular (43.0%), chronic (42.1%), fluctuation-related (34.6%) and orofacial pain (16.8%). Most patients (74.8%) experienced more than one pain subtype. Fluctuation-related pain and orofacial pain were significantly more prevalent among patients with higher Hoehn & Yahr (H&Y) stages (3-5) versus lower H&Y stages (1-2). Pain subtype and severity were not significantly related to gender or age of PD onset. Patients with H&Y stages 3-5 had statistically significantly higher KPPS scores for fluctuation-related pain (p = 0.018) and radicular pain (p = 0.026). Independent associations were found between pain severity and age (p = 0.028), depression severity (p = 0.018), perceptual problems/hallucinations (p = 0.033) and sexual function (p = 0.024). Patients with depression and higher H&Y stages (3-5) had statistically significantly higher mean KPPS scores versus patients without depression and at lower H&Y stages (1-2). Pain may be more common and severe in EOPD patients than previously appreciated. Older age, depression, perceptual problems/hallucinations and sexual dysfunction were independently associated with higher pain severity.

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.

Parkinson's Disease-related Pains are Not Equal: Clinical, Somatosensory and Cortical Excitability Findings in Individuals With Nociceptive Pain

Chronic pain is a frequent and burdensome nonmotor symptom of Parkinson's disease (PD). PD-related chronic pain can be classified as nociceptive, neuropathic, or nociplastic, the former being the most frequent subtype. However, differences in neurophysiologic profiles between these pain subtypes, and their potential prognostic and therapeutic implications have not been explored yet. This is a cross-sectional study on patients with PD (PwP)-related chronic pain (ie, started with or was aggravated by PD). Subjects were assessed for clinical and pain characteristics through questionnaires and underwent quantitative sensory tests and motor corticospinal excitability (CE) evaluations. Data were then compared between individuals with nociceptive and non-nociceptive (ie, neuropathic or nociplastic) pains. Thirty-five patients were included (51.4% male, 55.7 ± 11.0 years old), 20 of which had nociceptive pain. Patients with nociceptive PD-related pain had lower warm detection threshold (WDT, 33.34 ± 1.39 vs 34.34 ± 1.72, P = .019) and mechanical detection threshold (MDT, 2.55 ± 1.54 vs 3.86 ± .97, P = .007) compared to those with non-nociceptive pains. They also presented a higher proportion of low rest motor threshold values than the non-nociceptive pain ones (64.7% vs 26.6%, P = .048). In non-nociceptive pain patients, there was a negative correlation between WDT and non-motor symptoms scores (r = -.612, P = .045) and a positive correlation between MDT and average pain intensity (r = .629, P = .038), along with neuropathic pain symptom scores (r = .604, P = .049). It is possible to conclude that PD-related chronic pain subtypes have distinctive somatosensory and CE profiles. These preliminary data may help better frame previous contradictory findings in PwP and may have implications for future trial designs aiming at developing individually-tailored therapies. PERSPECTIVE: This work showed that PwP-related nociceptive chronic pain may have distinctive somatosensory and CE profiles than those with non-nociceptive pain subtypes. These data may help shed light on previous contradictory findings in PwP and guide future trials aiming at developing individually-tailored management strategies.

PACAP/PAC1-R activation contributes to hyperalgesia in 6-OHDA-induced Parkinson's disease model rats via promoting excitatory synaptic transmission of spinal dorsal horn neurons

Pain is a common annoying non-motor symptom in Parkinson's disease (PD) that causes distress to patients. Treatment for PD pain remains a big challenge, as its underlying mechanisms are elusive. Pituitary adenylate cyclase-activating polypeptide (PACAP) and its receptor PAC1-R play important roles in regulating a variety of pathophysiological processes. In this study, we investigated whether PACAP/PAC1-R signaling was involved in the mechanisms of PD pain. 6-hydroxydopamine (6-OHDA)-induced PD model was established in rats. Behavioral tests, electrophysiological and Western blotting analysis were conducted 3 weeks later. We found that 6-OHDA rats had significantly lower mechanical paw withdrawal 50% threshold in von Frey filament test and shorter tail flick latency, while mRNA levels of Pacap and Adcyap1r1 (gene encoding PAC1-R) in the spinal dorsal horn were significantly upregulated. Whole-cell recordings from coronal spinal cord slices at L4-L6 revealed that the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) in dorsal horn neurons was significantly increased, which was reversed by application of a PAC1-R antagonist PACAP 6-38 (250 nM). Furthermore, we demonstrated that intrathecal microinjection of PACAP 6-38 (0.125, 0.5, 2 μg) dose-dependently ameliorated the mechanical and thermal hyperalgesia in 6-OHDA rats. Inhibition of PACAP/PAC1-R signaling significantly suppressed the activation of Ca2+/calmodulin-dependent protein kinase II and extracellular signal-regulated kinase (ERK) in spinal dorsal horn of 6-OHDA rats. Microinjection of pAAV-Adcyap1r1 into L4-L6 spinal dorsal horn alleviated hyperalgesia in 6-OHDA rats. Intrathecal microinjection of ERK antagonist PD98059 (10 μg) significantly alleviated hyperalgesia in 6-OHDA rats associated with the inhibition of sEPSCs in dorsal horn neurons. In addition, we found that serum PACAP-38 concentration was significantly increased in PD patients with pain, and positively correlated with numerical rating scale score. In conclusion, activation of PACAP/PAC1-R induces the development of PD pain and targeting PACAP/PAC1-R is an alternative strategy for treating PD pain.

What is available to support pain management in Parkinson's: a scoping review protocol

OBJECTIVE

A scoping review will be undertaken to examine and map the available evidence that has been produced in relation to pain management in Parkinson's, with a focus on behavioural interventions, resources and/or how professionals support people with Parkinson's self-management of pain.

METHODS

This review will be based on the methodological framework given by Arksey and O'Malley's (2005), including enhancements by Levac et al., Peters et al. and the Joanna Briggs Institute. We will include studies from PubMed, SCOPUS, CINAHL, MEDLINE Web of Science, APA PsycINFO and ASSIA from January, 2010 onwards. Both quantitative and qualitative data will be analysed separately to identify the characteristics of support for pain management available, orientation of the approach and any identifiable behaviour change components and their outcomes. The COM-B behaviour change model and Theoretical Domains Framework will provide a theoretical framework for synthesising evidence in this review.

CONCLUSION

This scoping review will help to explore studies focusing on the evidence supporting a range of interventions relating to the management of pain experienced by people living with Parkinson's. The focus will be on describing what is available to support self-management, identify what behaviour change components have been used and their effectiveness, identify barriers and enablers to pain management and explore gaps in current provision of pain management. This review will identify implications and priorities for the follow-up phases to the larger 'Pain in Parkinson's' Project which is designed to support clinicians and individuals living with Parkinson's.

Pain in Parkinson disease: mechanistic substrates, main classification systems, and how to make sense out of them

ABSTRACT

Parkinson disease (PD) affects up to 2% of the general population older than 65 years and is a major cause of functional loss. Chronic pain is a common nonmotor symptom that affects up to 80% of patients with (Pw) PD both in prodromal phases and during the subsequent stages of the disease, negatively affecting patient's quality of life and function. Pain in PwPD is rather heterogeneous and may occur because of different mechanisms. Targeting motor symptoms by dopamine replacement or with neuromodulatory approaches may only partially control PD-related pain. Pain in general has been classified in PwPD according to the motor signs, pain dimensions, or pain subtypes. Recently, a new classification framework focusing on chronic pain was introduced to group different types of PD pains according to mechanistic descriptors: nociceptive, neuropathic, or neither nociceptive nor neuropathic. This is also in line with the International Classification of Disease-11 , which acknowledges the possibility of chronic secondary musculoskeletal or nociceptive pain due to disease of the CNS. In this narrative review and opinion article, a group of basic and clinical scientists revise the mechanism of pain in PD and the challenges faced when classifying it as a stepping stone to discuss an integrative view of the current classification approaches and how clinical practice can be influenced by them. Knowledge gaps to be tackled by coming classification and therapeutic efforts are presented, as well as a potential framework to address them in a patient-oriented manner.

Safety and tolerability of long-term apomorphine infusion in advanced Parkinson's disease: an Indian multi-center (APO-IND) experience

Advanced Parkinson's Disease (APD) is complicated by the emergence of motor and non-motor fluctuations, which are initially predictable and eventually become unpredictable, in part due to erratic gastric absorption and short half of oral levodopa. Attempts to manage such fluctuations with oral dopaminergic drugs often lead to disabling dyskinesias. Continuous Subcutaneous Apomorphine Infusion (CSAI), despite being approved for the treatment of APD since 1993, was approved in India only in 2019. We studied the safety, tolerability and efficacy of CSAI in Indian patients with APD in a registry design to raise local awareness of this important treatment. We conducted a prospective registry-based observational audit at 10 centers across different states of India. Patients with APD, not responding to or with significant side effects from oral dopaminergic therapy, were assessed at baseline and at month 6 and 12 following CSAI infusion. Fifty-one patients completed the study, CSAI significantly reduced the functional impact of dyskinesia (p < 0.01 at 6 months and p < 0.001 at 12 months). There was a significant improvement in the OFF-state from baseline (p < 0.01 at 6 months and p < 0.001 at 12 months) No discernible side effects were observed apart from mild site reaction (n = 7), nausea (n = 7) skin nodules (n = 2). CSAI demonstrated safety, efficacy, tolerability and improved quality of life in patients with APD, as shown in previous studies. Our study highlighted current existing inequalities in treatment availability, lack of awareness, knowledge gap, affordability and cost remains a concern regarding apomorphine use in Indian PD population.

Pain in monogenic Parkinson's disease: a comprehensive review

Pain, a challenging symptom experienced by individuals diagnosed with Parkinson's disease (PD), still lacks a comprehensive understanding of its underlying pathophysiological mechanisms. A systematic investigation of its prevalence and impact on the quality of life in patients affected by monogenic forms of PD has yet to be undertaken. This comprehensive review aims to provide an overview of the association between pain and monogenic forms of PD, specifically focusing on pathogenic variants in SNCA, PRKN, PINK1, PARK7, LRRK2, GBA1, VPS35, ATP13A2, DNAJC6, FBXO7, and SYNJ1. Sixty-three articles discussing pain associated with monogenic PD were identified and analyzed. The included studies exhibited significant heterogeneity in design, sample size, and pain outcome measures. Nonetheless, the findings of this review suggest that patients with monogenic PD may experience specific types of pain depending on the pathogenic variant present, distinguishing them from non-carriers. For instance, individuals with SNCA pathogenic variants have reported painful dystonia, lower extremity pain, dorsal pain, and upper back pain. However, these observations are primarily based on case reports with unclear prevalence. Painful lower limb dystonia and lower back pain are prominent symptoms in PRKN carriers. A continual correlation has been noted between LRRK2 mutations and the emergence of pain, though the conflicting research outcomes pose challenges in reaching definitive conclusions. Individuals with PINK1 mutation carriers also frequently report experiencing pain. Pain has been frequently reported as an initial symptom and the most troublesome one in GBA1-PD patients compared to those with idiopathic PD. The evidence regarding pain in ATP13A2, PARK7, VPS35, DNAJC6, FBXO7, and SYNJ1pathogenic variants is limited and insufficient. The potential linkage between genetic profiles and pain outcomes holds promising clinical implications, allowing for the potential stratification of patients in clinical trials and the development of personalized treatments for pain in monogenic PD. In conclusion, this review underscores the need for further research to unravel the intricate relationship between pain and monogenic forms of PD. Standardized methodologies, larger sample sizes, and longitudinal studies are essential to elucidate the underlying mechanisms and develop targeted therapeutic interventions for pain management in individuals with monogenic PD.

Defining the causes of sporadic Parkinson's disease in the global Parkinson's genetics program (GP2)

The Global Parkinson's Genetics Program (GP2) will genotype over 150,000 participants from around the world, and integrate genetic and clinical data for use in large-scale analyses to dramatically expand our understanding of the genetic architecture of PD. This report details the workflow for cohort integration into the complex arm of GP2, and together with our outline of the monogenic hub in a companion paper, provides a generalizable blueprint for establishing large scale collaborative research consortia.

Towards a better Comprehension and Management of Pain and Psychological Distress in Parkinson's: The Role of Catastrophizing

OBJECTIVES

Pain is very prevalent in Parkinson's and challenging to manage. As many people with Parkinson's (PwP) with pain suffer from anxious and depressive symptoms, we examined the role of catastrophizing in mediating the relationship between pain and psychological distress for this population.

METHODS

169 international PwP completed an online survey with socio-demographic and medical data. Participants completed psychometric tests to assess their pain (King's Parkinson's Disease Pain Questionnaire, McGill Pain Questionnaire and Brief Pain Inventory), psychological distress (Beck Depression Inventory and Parkinson Anxiety Scale), pain coping strategies (Coping Strategies Questionnaire) and pain catastrophizing (Pain Catastrophizing Scale).

RESULTS

Depending on the tool used, 82.8% to 95.2% of participants reported pain. 23.5 % and 67.5% of participants showed respectively significant levels of depressive and anxiety symptoms. Psychological distress was significantly correlated with the quality of pain (both sensory and affective dimensions). Statistical models highlighted the mediating role of catastrophizing in the relationship between psychological distress and pain in Parkinson's.

CONCLUSION

These findings offer new perspectives toward understanding the underlying mechanisms of pain in Parkinson's and for effective therapeutic intervention goals to facilitate adaptation to pain symptoms in Parkinson's.

Dorsal subthalamic deep brain stimulation improves pain in Parkinson's disease

Introduction

Inconsistent effects of subthalamic deep brain stimulation (STN DBS) on pain, a common non-motor symptom of Parkinson's disease (PD), may be due to variations in active contact location relative to some pain-reducing locus of stimulation. This study models and compares the loci of maximal effect for pain reduction and motor improvement in STN DBS.

Methods

We measured Movement Disorder Society Unified PD Rating Scale (MDS-UPDRS) Part I pain score (item-9), and MDS-UPDRS Part III motor score, preoperatively and 6-12 months after STN DBS. An ordinary least-squares regression model was used to examine active contact location as a predictor of follow-up pain score while controlling for baseline pain, age, dopaminergic medication, and motor improvement. An atlas-independent isotropic electric field model was applied to distinguish sites of maximally effective stimulation for pain and motor improvement.

Results

In 74 PD patients, mean pain score significantly improved after STN DBS (p = 0.01). In a regression model, more dorsal active contact location was the only significant predictor of pain improvement (R2 = 0.17, p = 0.03). The stimulation locus for maximal pain improvement was lateral, anterior, and dorsal to that for maximal motor improvement.

Conclusion

STN stimulation, dorsal to the site of optimal motor improvement, improves pain. This region contains the zona incerta, which is known to modulate pain in humans, and may explain this observation.

King's Parkinson's Disease Pain Questionnaire: reliability and convergent construct validity

OBJECTIVES

to assess the evidence of reliability and convergent construct validity of the King's Parkinson's Disease Pain Questionnaire.

METHODS

psychometric study of 75 older adults with Parkinson's disease. The instrument was applied by two researchers separately and reapplied by one researcher 15 days later. In terms of reliability, internal consistency was assessed using the Cronbach's alpha test and stability using the intraclass correlation coefficient. Scores of the King's Parkinson's Disease Pain Questionnaire were compared to those of the Geriatric Pain Measure in the assessment of construct validity.

RESULTS

the mean Cronbach's alpha obtained between the three assessments was above 0.60, the intraclass correlation between the three assessments was above 0.90, and there was a weak but significant correlation between the two applied scales.

CONCLUSIONS

the instrument showed adequate evidence of convergent construct validity and reliability, and can be used in clinical practice.

A Phase Ib, Double Blind, Randomized Study of Cannabis Oil for Pain in Parkinson's Disease

Background

Pain is common in Parkinson's disease (PD), but effective therapies are limited.

Objectives

To determine the maximum tolerated dose (MTD) and safety of formulations of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) for pain in PD.

Methods

In this phase 1b, double-blind, randomized, single-center study, participants were randomized to three formulations of THC/CBD (18:0, 10:10, and 1:20). The MTD, adverse events (AE), and tolerability are described for each formulation.

Results

Eight participants were randomized. The MTD was similar among groups (0.8-0.9 mL/daily), and there were no serious AE or study drop-outs. The most common AE were drowsiness and dizziness (three participants). Epworth sleepiness scale scores were higher in the high CBD formulation (1:20).

Conclusions

In patients with pain and PD, mixed formulations of THC/CBD were tolerated with no serious AE. Considering the safety profile, future phase II studies should be considered.

Burning mouth disorder and Parkinson's disease: A scoping review of the literature

BACKGROUND

Burning mouth disorder (BMD) is a complex medical condition characterized by a burning sensation in the mouth of fluctuating intensity. BMD is considered a diagnosis of exclusion, as oral burning can occur secondary to local or systemic conditions. Parkinson's disease (PD) is one such condition.

OBJECTIVE

To provide a scoping review of the literature by assessing all articles written in English that investigated the relationship between BMD and PD.

MATERIALS AND METHODS

Various databases (PubMed, Ovid, Web of Science, Science Direct and Scopus) and a search platform (EBSCOhost) were searched following similar investigative approaches. Duplicates were removed and reference lists of original studies were scrutinized for additional articles. Any decision about the inclusion/exclusion in the review was by consensus among the co-authors.

RESULTS

Twenty-five original articles and one supplemental article were included in the final review, of which 13 met the inclusion criteria. These were further divided into five categories based on the study design/article, which included Prevalence studies (n = 6), Letter to the editor (n = 1), Incidence study (n = 1), Case reports (n = 2) and Experimental studies (n = 3). Strongest data was provided by epidemiological studies, which suggest BMD and PD are poorly associated.

CONCLUSIONS

A scoping review of the existing literature does not suggest that PD patients are any more at risk of developing BMD compared to the general population. While there may be a link through the dopaminergic system as determined by imaging studies, it is unlikely that the pathogenesis of PD disease shares significant commonality with BMD.

Eleven-Year Outcomes of Deep Brain Stimulation in Early-Stage Parkinson Disease

OBJECTIVE

The deep brain stimulation (DBS) in early-stage Parkinson's disease (PD) pilot clinical trial randomized 30 patients (Hoehn & Yahr II off; medication duration 0.5-4 years; without dyskinesia/motor fluctuations) to optimal drug therapy (ODT) (early ODT) or bilateral subthalamic nucleus (STN) DBS plus ODT (early DBS+ODT). This study aims to report the 11-year outcomes of patients who completed the DBS in early-stage PD pilot clinical trial.

MATERIALS AND METHODS

Attempts were made to contact all 29 subjects who completed the two-year trial to participate in an 11-year follow-up study. Mixed-effects models compared overall trend in outcomes for randomization groups (fixed-effects: assigned treatment, year, their interaction; random-effect: subject) to account for repeated measures.

RESULTS

Twelve subjects participated in this 11-year follow-up study (n = 8 early ODT, n = 4 early DBS+ODT). Participating subjects were 70.0 ± 4.8 years old with a PD medication duration of 13.7 ± 1.7 years (early DBS duration 11.5 ± 1.3 years, n = 4). Three early ODT subjects received STN-DBS as standard of care (DBS duration 6.5 ± 2.0 years). Early ODT subjects had worse motor complications (Unified Parkinson's Disease Rating Scale [UPDRS]-IV) than early DBS+ODT subjects over the 11-year follow-up period (between-group difference = 3.5 points; pinteraction = 0.03). Early DBS+ODT was well-tolerated after 11 years and showed comparable outcomes to early ODT for other UPDRS domains, Parkinson Disease Questionnaire-39 (PDQ-39), and levodopa equivalent daily dose (LEDD).

CONCLUSIONS

Eleven years after randomization, early DBS+ODT subjects had fewer motor complications than early ODT subjects. These results should be interpreted with caution because only 40% of pilot trial subjects participated in this 11-year follow-up study. The Food and Drug Administration has approved the conduct of a pivotal clinical trial evaluating DBS in early-stage PD (IDEG050016).

CLINICAL TRIAL REGISTRATION

The Clinicaltrials.gov registration number for the study is NCT00282152.

Axial postural abnormalities and pain in Parkinson's disease

Axial postural abnormalities and pain are two main determinants of poor quality of life in patients with Parkinson's disease (PD). Indeed, a detailed characterization of pain and other non-motor symptoms in patients with PAs has not been provided yet. The aim of this study is to assess the phenomenology of pain and other non-motor symptoms in PD patients with Pisa syndrome and camptocormia compared to PD patients without axial postural abnormality. Forty-five PD participants were equally distributed in three groups: patients with Pisa syndrome (PS), patients with Camptocormia (CC), and patients without postural abnormalities (PD). Pain characteristics were assessed by Kings Parkinson's Pain Scale (KPPS), brief pain inventory (BPI), and numeric pain rating scale (NRS). All participants completed clinical assessments by non-motor symptom scale (NMSS), and movement disorder society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) parts II-III. Patients with and without axial postural abnormalities showed one or more types of pain, being fluctuation, nocturnal, chronic, and musculoskeletal the most frequently reported in Pisa Syndrome and camptocormia. PD group compared with PS and CC groups showed differences in the KPPS, NMSS, BPI pain severity and interference, and NRS total scores. No significant differences were found between PS group compared with CC group with exception of the NMSS total scores. PD patients with Pisa syndrome or camptocormia have a higher burden of musculoskeletal, chronic and fluctuation pain than PD patients without axial postural abnormalities, suggesting different etiologies of pain and possible different treatments.

Effectiveness and Therapeutic Mechanism of Pharmacopuncture for Pain in Parkinson's Disease: A Study Protocol for a Pilot Pragmatic Randomized, Assessor-Blinded, Usual Care-Controlled, Three-Arm Parallel Trial

Pain in Parkinson's disease (PD) represents a complex phenotype known to decrease quality of life. This pragmatic randomized, controlled clinical trial evaluated the efficacy of pharmacopuncture (PA) for improving pain symptoms and investigated the corresponding therapeutic mechanisms in patients with PD. Ninety patients with PD-related pain were randomly allocated to receive either PA, manual acupuncture, or usual care in a 1:1:1 ratio; sixty healthy controls were included for comparative analysis of brain imaging data. Over 12 weeks, study treatment provided 2 days per week for 8 weeks with a follow-up period of 4 weeks. The primary outcome measure was the King's Parkinson's Disease Pain Scale score for assessing improvement in PD-related pain, including a sub-analysis to investigate the pattern of changes in pain according to a PD-related pain mechanism-based classification. Secondary outcome measures included a numerical rating scale-based assessment of the intensity and location of pain and changes in pain-associated symptoms, such as depression, anxiety, and sleep disorders. Exploratory outcome measures included structural and functional brain patterns on magnetic resonance imaging, blood molecular signature changes, gait analysis, facial expression and movement assessment in response to emotional stimuli, and a traditional Korean medicine syndrome differentiation questionnaire. The trial findings provided important clinical evidence for the effectiveness of PA in the management of PD-related pain and its associated symptoms, and helped elucidate the mechanism of its therapeutic effect on PD-related pain.

Outcome Measures for Disease-Modifying Trials in Parkinson's Disease: Consensus Paper by the EJS ACT-PD Multi-Arm Multi-Stage Trial Initiative

BACKGROUND

Multi-arm, multi-stage (MAMS) platform trials can accelerate the identification of disease-modifying treatments for Parkinson's disease (PD) but there is no current consensus on the optimal outcome measures (OM) for this approach.

OBJECTIVE

To provide an up-to-date inventory of OM for disease-modifying PD trials, and a framework for future selection of OM for such trials.

METHODS

As part of the Edmond J Safra Accelerating Clinical Trials in Parkinson Disease (EJS ACT-PD) initiative, an expert group with Patient and Public Involvement and Engagement (PPIE) representatives' input reviewed and evaluated available evidence on OM for potential use in trials to delay progression of PD. Each OM was ranked based on aspects such as validity, sensitivity to change, participant burden and practicality for a multi-site trial. Review of evidence and expert opinion led to the present inventory.

RESULTS

An extensive inventory of OM was created, divided into: general, motor and non-motor scales, diaries and fluctuation questionnaires, cognitive, disability and health-related quality of life, capability, quantitative motor, wearable and digital, combined, resource use, imaging and wet biomarkers, and milestone-based. A framework for evaluation of OM is presented to update the inventory in the future. PPIE input highlighted the need for OM which reflect their experience of disease progression and are applicable to diverse populations and disease stages.

CONCLUSION

We present a range of OM, classified according to a transparent framework, to aid selection of OM for disease-modifying PD trials, whilst allowing for inclusion or re-classification of relevant OM as new evidence emerges.

Evaluation of perception threshold and pain in patients with Parkinson's disease using PainVision®

Introduction

Pain is one of the most frequent non-motor symptoms occurring in patients with Parkinson's disease (PD). Traditionally, the Visual Analog Pain Scale (VAS), Numerical Rating Scale (NRS), and Wong-Baker Faces Pain Rating Scale (FRS) have been used for clinical pain assessment, but these assessments are subjective at best. In contrast, PainVision^® is a perceptual/pain analyzer that can quantitatively evaluate pain as "pain intensity" based on "current perception threshold" and "pain equivalent current." We evaluated the current perception threshold in all PD patients and pain intensity in PD patients with pain using PainVision^®.

Methods

We recruited 48 patients with PD (PwPD) with pain and 52 PwPD without pain. For patients with pain, we measured current perception threshold, pain equivalent current, and pain intensity using PainVision^®, in addition to evaluation by VAS, NRS, and FRS. For patients without pain, only current perception threshold was measured.

Results

There was no correlation with either VAS or FRS, whereas only weak correlation was identified for NRS (γ = -0.376) with pain intensity. Current perception threshold was positively correlated with duration of the disease (γ = 0.347) and the Hoehn and Yahr stage (γ = 0.259). As a quantitative evaluation of pain, pain intensity by PainVision^® does not correlate with conventional subjective pain assessments.

Discussion

This new quantitative evaluation method of pain may be suitable as an evaluation tool for future intervention research. Current perception threshold in PwPD was related to the duration and severity of the disease and may be involved in peripheral neuropathy associated with PD.

Psychometric features of brief pain inventory for Parkinson's disease during medication states

PURPOSE

Patients with idiopathic Parkinson's disease (PD) suffer from different non-motor symptoms, including pain. The present study aimed to measure the psychometric properties of the Brief Pain Inventory (BPI) in patients with PD during ON- and OFF-states.

METHODS

We recruited 460 patients with PD and 100 non-PD controls. The pain was assessed by the BPI, King's Parkinson's disease Pain Scale (KPPS), Neuropathic Pain Symptom Inventory (NPSI), Visual Analogue Scale-Pain (VAS-pain), and short-form McGill Pain Questionnaire-2 (SF-MPQ-2) in both medication states. Internal consistency and test-retest reliability was examined using Cronbach's alpha coefficient and intra-class correlation coefficient (ICC). Dimensionality and convergent validity of BPI were also investigated. Diagnostic accuracy and discriminative validity were determined by Receiver Operating Characteristics (ROC) curve analysis and Area Under the Curve (AUC).

RESULTS

Cronbach's alpha was satisfactory (α = 0.91-0.97) in both states. The ICC values were 0.85-0.96 in ON- and OFF-state. Factor analysis revealed two factors. A high correlation was obtained between BPI subscales and other scales. AUC >0.91, sensitivity, and specificity> 0.77 were observed for discriminating different pain levels. Furthermore, appropriate diagnostic accuracy was found (AUC, sensitivity, and specificity >0.67) between non-PD control and PD patients.

CONCLUSION

The BPI has acceptable psychometric features as well as diagnostic accuracy for patients with PD.Implications for rehabilitationPain as a non-motor symptom in PD can affect daily and social activities.The BPI is used to assess pain severity and interference in activities.For better treatment, pain should be assessed in off-state like to on-state.BPI has satisfactory reliability and validity in different medication states in PD.

Proinflammatory profile in the skin of Parkinson's disease patients with and without pain

Background

Pain is a common non-motor symptom of Parkinson`s disease (PD), however, its pathomechanism remains elusive.

Objective

We aimed to investigate the local gene expression of selected proinflammatory mediators in patients with PD and correlated our data with patients`pain phenotype.

Methods

We recruited 30 patients with PD and 30 healthy controls. Pain intensity of patients was assessed using the Numeric Rating Scale (NRS) and patients were stratified into PD pain (NRS≥4) and PD No Pain (NRS<4) subgroups. Skin punch biopsies were immunoassayed for protein-gene product 9.5 as a pan-neuronal marker and intraepidermal nerve fiber density (IEFND). Quantitative real-time polymerase chain reaction (qRT-PCR) analysis was performed to assess the gene expression of inflammatory mediators in the skin compared to controls.

Results

Patients with PD had lower distal IENFD compared to healthy controls. In skin samples, IL-2 (p<0.001) and TNF-α (p<0.01) were expressed higher in PD patients compared to controls. IL-1β (p<0.05) was expressed higher in the PD pain group compared to healthy controls. PD patients with pain receiving analgesics had a lower expression of TNF-α (p<0.05) in the skin compared to those not receiving treatment.

Conclusions

Our data suggest the occurrence of a local, peripheral inflammatory response in the skin in PD, but do not support this being a relevant factor contributing to pain in PD.

[Characteristics and treatment of pain in Parkinson's disease]

Pain is a representative non-motor symptom in patients with Parkinson's disease (PD). Pain is one of the most common symptoms that plague patients with PD regardless of the stage of the disease, also it can exacerbate other symptoms, such as depression, anxiety or sleep disturbance, and lead to impaired quality of life. However, pain is often not adequately evaluated and treated. PD patients complain of a wide variety of pain, including both PD-related pain which caused by PD-specific symptoms, for example, rigidity, bradykinesia or motor fluctuation, and PD-unrelated pain, and it can be divided into central and peripheral depending on the site of the disorder. In the medical care of the pain, it is important to evaluate the type and severity of the pain using PD-specific assessment scales such as King's PD pain scale and to consider the evidence-based treatment methods according to the pathophysiology of the pain.

First Two-Year Observational Exploratory Real Life Clinical Phenotyping, and Societal Impact Study of Parkinson’s Disease in Emiratis and Expatriate Population of United Arab Emirates 2019–2021: The EmPark Study

Background: Phenotypic differences in Parkinson’s Disease (PD) among locals (Emiratis) and Expatriates (Expats) living in United Arab Emirates have not been described and could be important to unravel local aspects of clinical heterogenicity of PD pointing towards genetic and epigenetic variations. Objective: To investigate the range and nature of motor and nonmotor clinical presentations of PD and its impact on time to diagnosis, local service provisions, and quality of life in Emiratis and Expats in UAE, as well as address the presence of current unmet needs on relation to care and etiopathogenesis of PD related to possible genetic and epigenetic factors. Methods: a cross-sectional one point in time prospective, observational real-life study of 171 patients recruited from PD and Neurology clinics across United Arab Emirates from 2019–2021. Primary outcomes were sociodemographic data, motor and nonmotor symptoms (NMS), including cognition and sleep, and quality of life (QOL) assessments, Results: A total of 171 PD patients (52 Emiratis 119 Expats) were included with mean age (Emiratis 48.5 (13.1) Expats 64.15 (13.1)) and mean disease duration (Emiratis 4.8 (3.2) Expats 6.1 (2.9)). In the Emiratis, there was a significant mean delay in initiating treatment after diagnosis (Emiratis 1.2 (0.9) Expats 1.6 (1.1)), while from a clinical phenotyping aspect, there is a high percentage of akinesia 25 (48.1) or tremor dominant (22 (42.3)) phenotypes as opposed to mixed subtype 67 (56.3) in Expat cohorts; double tremor dominant, especially Emirati females (25%), had a predominant lower limb onset PD. Both Emirati (27.9 (24.0)) and Expat 29.4 (15.6) showed moderate NMS burden and the NMS profile is dominated by Sleep, Fatigue, Mood, Emotional well-being 3.0 (1.1) and Social Stigma 3.5 (0.9) aspects of PDQ8 SI measurements are predicted worse QOL in Emiratis, while lack of social support 2.3 (1.3) impaired QOL in Expat population. Awareness for advanced therapies was low and only 25% of Emiratis were aware of deep brain surgery (DBS), compared to 69% Expats. Only 2% of Emiratis, compared to 32% of Expats, heard of Apomorphine infusion (CSAI), and no (0%) Emiratis were aware of intrajejunal levodopa infusion (IJLI), compared to 13% of expats. Conclusion: Our pilot data suggest clinical phenotypic differences in presentation of PD in Emiratis population of UAE compared to expats. Worryingly, the data also show delayed treatment initiation, as well as widespread lack of knowledge of advanced therapies in the Emirati population.

A Survey of People With Parkinson's and Their Carers: The Management of Pain in Parkinson's

BACKGROUND

Pain in Parkinson's is problematic but under treated in clinical practice. Healthcare professionals must understand the impact of pain in Parkinson's and patient preferences for management.

OBJECTIVE

To understand the impact of pain in Parkinson's and to understand current management and preferences for pain management.

METHODS

We conducted a national survey with 115 people with Parkinson's (PwP) and 10 carers. Both closed and open questions were used. The questions focused on how pain affected the individual, healthcare professional involvement in supporting pain management, current pain management strategies and views on future pain management interventions. We used descriptive statistics to summarize closed responses and thematic analysis to summarize open question responses.

RESULTS

70% of participants reported pain impacted their daily life. Pain had a multifactorial impact on participants, affecting movement, mood and quality of life. Improved pain management was viewed to have the potential to address each of these challenges. Pain affected a number of different sites, with low back pain and multiple sites being most frequently reported. Exercise was the most frequently noted strategy (38%) recommended by healthcare professionals for pain management. PwP would value involvement from healthcare professionals for future pain management, but also would like to self-manage the condition. Medication was not suggested as a first line strategy.

CONCLUSIONS

Despite reporting engagement in some strategies to manage pain, pain still has a wide-ranging impact on the daily life of PwP. Results from this survey highlight the need to better support PwP to manage the impact of pain.

Validation of new diagnostic criteria for fatigue in patients with Parkinson's disease

Background and purpose

Although disabling fatigue is common in Parkinson disease (PD), available consensus‐based diagnostic criteria have not yet been empirically validated. The aim of this study was to evaluate the clinimetric properties of the criteria.

Methods

A sample of outpatients with PD was evaluated for demographic, clinical, behavioral, and cognitive features. Fatigue was diagnosed according to the new diagnostic criteria and was rated by means of the Parkinson Fatigue Scale (PFS) and Fatigue Severity Scale (FSS). Acceptability, concurrent and discriminant validity, and interrater reliability were evaluated with binary logistic regression analyses and Cohen kappa (κ).

Results

Of 241 included patients, 17 (7.1%) met the diagnostic criteria for PD‐related fatigue. Eight of nine symptoms described in Section A of the diagnostic criteria occurred in >50% of patients with fatigue. Acceptability (missing data = 0.8%) of the criteria was good, as was their concurrent validity with the PFS (odds ratio = 3.65) and FSS (odds ratio = 3.63). The discriminant validity of fatigue criteria with other PD‐related behavioral and cognitive features was good (odds ratio < 1.68). The interrater reliability was excellent (κ = 0.92).

Conclusions

This is the first study to test the clinimetric properties of case definition diagnostic criteria for PD‐related fatigue. Our results suggest that current diagnostic criteria may be useful in both clinical practice and research. Future longitudinal studies should examine their long‐term stability.

Minimal clinically important difference of the King's Parkinson's disease Pain Scale

OBJECTIVE

Pain is a common and debilitating symptom of Parkinson's disease (PD) and has no specific treatment. King's Parkinson's disease Pain Scale (KPPS) is the only specific scale for pain measurement in PD with established psychometric properties. The minimal clinically important difference (MCID) of KPPS, an important parameter for the design and interpretation of therapeutic interventions, has not yet been measured. The aim of our study was to assess the MCID of KPPS.

METHODS

Two hundred and seven PD patients were evaluated by KPPS before and after receiving the intervention. The Clinical Global Impression of Improvement Scale was used as an anchor, and a Receiver Operating Characteristic (ROC) curve was used to determine the optimal MCID cut-off point for KPPS. The distribution-based approach applied one-third standard deviation (SD), 0.5 SD, and one standard error of measurement (SEM) of the total score of KPPS to determine the MCID.

RESULTS

The MCID achieved from the ROC curve was 3 points (sensitivity: 74.4%; specificity: 81.9%). For the distribution-based method, the MCIDs corresponding to 0.3 SD, 0.5 SD, and one SEM were 5.65, 9.41, and 2.54 points, respectively.

CONCLUSION

KPPS is a valid scale for measuring pain in PD with demonstrable MCID. IMPLICATIONS FOR REHABILITATIONThe King's Parkinson's disease Pain Scale (KPPS) is a valid scale for measuring pain in patients with Parkinson's disease (PD) with demonstrable minimal clinically important difference (MCID).The MCID obtained in the current study will assist clinicians and researchers when interpreting KPPS change score to determine clinically meaningful changes of pain in both PD progression and response to interventions.

Abnormal connectivity model of raphe nuclei with sensory-associated cortex in Parkinson's disease with chronic pain

BACKGROUND AND OBJECTIVE

There are indicates that raphe nuclei may be involved in the occurrence of chronic pain in Parkinson's disease (PD). In the study, we investigated the functional connectivity pattern of raphe nuclei in Parkinson's disease with chronic pain (PDP) to uncover its possible pathophysiology.

METHODS

Fifteen PDP, who suffered from pain, lasted longer than 3 months, sixteen Parkinson's disease patients with no pain (nPDP) and eighteen matched normal health controls (NCs) were recruited. All subjects completed the King's Parkinson's Pain Scale (KPPS) besides Parkinson-related scale and demographics. We performed a seed-based resting-state analysis of functional magnetic resonance imaging to explore whole-brain functional connectivity of the raphe nuclei. Multiple regression model was used to explore the related factors of pain including disease duration, disease severity, Hamilton Depression Rating Scale, age, sex, levodopa equivalent dose and the strength of network functional connectivity.

RESULTS

Compared with the nPDP, the PDP group showed stronger functional connectivity between raphe nuclei and pain-related brain regions, including parietal lobe, insular lobe, cingulum cortex and prefrontal cortex, and the functional connectivity values of those areas were significantly positively correlated with KPPS independent of the clinical variables. Compared with NCs, the combined PD groups showed decreased functional connectivity including prefrontal cortex and cingulum cortex.

CONCLUSIONS

Abnormal functional connectivity model of raphe nuclei may be partly involved in pathophysiological mechanism of pain in PD.

Idiopathic Parkinson's disease and chronic pain in the era of deep brain stimulation: a systematic review and meta-analysis

OBJECTIVE

Pain is the most common nonmotor symptom of Parkinson's disease (PD) and is often undertreated. Deep brain stimulation (DBS) effectively mitigates the motor symptoms of this multisystem neurodegenerative disease; however, its therapeutic effect on nonmotor symptoms, especially pain, remains inconclusive. While there is a critical need to help this large PD patient population, guidelines for managing this significant disease burden are absent. Herein, the authors systematically reviewed the literature and conducted a meta-analysis to study the influence of traditional (subthalamic nucleus [STN] and globus pallidus internus [GPi]) DBS on chronic pain in patients with PD.

METHODS

The authors performed a systematic review of the literature and a meta-analysis following PRISMA guidelines. Risk of bias was assessed using the levels of evidence established by the Oxford Centre for Evidence-Based Medicine. Inclusion criteria were articles written in English, published in a peer-reviewed scholarly journal, and about studies conducting an intervention for PD-related pain in no fewer than 5 subjects.

RESULTS

Twenty-six studies were identified and included in this meta-analysis. Significant interstudy heterogeneity was detected (Cochran's Q test p < 0.05), supporting the use of the random-effects model. The random-effects model estimated the effect size of DBS for the treatment of idiopathic pain as 1.31 (95% CI 0.84-1.79). The DBS-on intervention improved pain scores by 40% as compared to the control state (preoperative baseline or DBS off).

CONCLUSIONS

The results indicated that traditional STN and GPi DBS can have a favorable impact on pain control and improve pain scores by 40% from baseline in PD patients experiencing chronic pain. Further trials are needed to identify the subtype of PD patients whose pain benefits from DBS and to identify the mechanisms by which DBS improves pain in PD patients.