Enhanced temporal pain processing in multiple system atrophy

On location for cannabinoid control of multimodal behavior

In this issue of Neuron, Soria-Gomez et al. (2021) investigate whether activation of the type 1 cannabinoid receptor at specific subcellular locations within a single neural circuit produces multimodal behavior. Their results demonstrate that location matters: striatonigral mitochondrial CB1 drives catalepsy while striatonigral plasma membrane CB1 receptors enable antinociception.

Towards optimising experimental quantification of persistent pain in Parkinson's disease using psychophysical testing

People with Parkinson's disease (PD) may live for multiple decades after diagnosis. Ensuring that effective healthcare provision is received across the range of symptoms experienced is vital to the individual's wellbeing and quality of life. As well as the hallmark motor symptoms, PD patients may also suffer from non-motor symptoms including persistent pain. This type of pain (lasting more than 3 months) is inconsistently described and poorly understood, resulting in limited treatment options. Evidence-based pain remedies are coming to the fore but therapeutic strategies that offer an improved analgesic profile remain an unmet clinical need. Since the ability to establish a link between the neurodegenerative changes that underlie PD and those that underlie maladaptive pain processing leading to persistent pain could illuminate mechanisms or risk factors of disease initiation, progression and maintenance, we evaluated the latest research literature seeking to identify causal factors underlying persistent pain in PD through experimental quantification. The majority of previous studies aimed to identify neurobiological alterations that could provide a biomarker for pain/pain phenotype, in PD cohorts. However heterogeneity of patient cohorts, result outcomes and methodology between human psychophysics studies overwhelmingly leads to inconclusive and equivocal evidence. Here we discuss refinement of pain-PD paradigms in order that future studies may enhance confidence in the validity of observed effect sizes while also aiding comparability through standardisation. Encouragingly, as the field moves towards cross-study comparison of data in order to more reliably reveal mechanisms underlying dysfunctional pain processing, the potential for better-targeted treatment and management is high.

A Comparison of Pain between Parkinson's Disease and Multiple System Atrophy: A Clinical Cross-Sectional Survey

Background

Pain is frequent in Parkinson's disease (PD) and Parkinson-plus syndrome. This study aimed to assess the prevalence, characteristics, therapy (especially the effect of dopaminergic therapy), and associated symptoms of pain in Parkinson's disease and multiple system atrophy (MSA) patients.

Methods

Seventy-one PD patients, sixty-five MSA patients, and forty age-matched healthy controls were enrolled and evaluated by using the German pain questionnaire and visual analogue scale (VAS). In addition, the influence of pain in PD patients on anxiety, depression, and the quality of life was assessed with the Hospital Anxiety and Depression Scale (HADS) and Parkinson's Disease Questionnaire (PDQ-39).

Results

Compared to that of the healthy controls, the PD and MSA patients had a significantly higher presence of pain (P < 0.01, P < 0.01). PD patients had a higher presence of pain than MSA patients (P=0.007). No difference in VAS scores was observed between the PD and MSA patients (P=0.148). A total of 21 PD patients (42.85%) with pain and 13 MSA patients (43.33%) with pain received treatment. A total of 13 PD patients with pain and 6 MSA patients with pain had an improved pain intensity after using dopaminergic medication. The differences in the disease duration, Hoehn and Yahr stages, and scores on the Unified Parkinson's Disease Rating Scale motor score, HAD-D, HAD-A, and PDQ-39 were significant between the PD patients with and without pain.

Conclusion

PD and MSA patients are prone to pain with insufficient treatment. Pain interventions should be provided as soon as possible to improve the patient's life.

Pain in Extrapyramidal Neurodegenerative Diseases

OBJECTIVE

Pain is one of the most common nonmotor symptoms of Parkinson disease (PD) and other Parkinson plus syndromes, with a major effect on quality of life. The aims of the study were to examine the prevalence and characteristics of pain in PD and other Parkinson plus syndromes and patient use and response to pain medications.

METHODS

The cohort consisted of 371 patients: 300 (81%) with PD and 71 (19%) with Parkinson plus syndromes. Data on clinical parameters and pain were collected by questionnaire. Disease severity was measured with the Unified PD Rating Scale for patients with PD.

RESULTS

Pain was reported by 277 patients (74%): 241 with PD and 36 with Parkinson plus syndromes. The prevalence of pain was significantly higher in the patients with PD than in the patients with Parkinson plus syndromes (80% vs. 50%, P<0.001) and higher in patients with synucleinopathies than in patients with tauopathies (70% vs. 40%, P<0.001). In the synucleinopathies, the most common pain was central pain (32%), whereas in the tauopathies only 4% of patients had central pain. Anti-Parkinson treatment relieved the pain in 21% of the patients with PD. Only 114 patients (48%) who experienced pain were treated with pain medications. The most beneficial analgesics were nonsteroidal anti-inflammatory drugs and medical cannabis.

CONCLUSION

Pain is prevalent among patients with PD and Parkinsonian plus syndromes. Pain relief can be achieved by more intensive anti-Parkinson medications or pain medications.

Pain processing in atypical Parkinsonisms and Parkinson disease: A comparative neurophysiological study

OBJECTIVE

Pain is a frequent non-motor feature in Parkinsonism but mechanistic data on the alteration of pain processing are insufficient to understand the possible causes and to define specifically-targeted treatments.

METHODS

we investigated spinal nociception through the neurophysiological measure of the threshold (TR) of nociceptive withdrawal reflex (NWR) and its temporal summation threshold (TST) comparatively in 12 Progressive Supranuclear Palsy (PSP) subjects, 11 Multiple System Atrophy (MSA) patients, 15 Parkinson's disease (PD) subjects and 24 healthy controls (HC). We also investigated the modulatory effect of L-Dopa in these three parkinsonian groups.

RESULTS

We found a significant reduction in the TR of NWR and in the TST of NWR in PSP, MSA and PD patients compared with HC. L-Dopa induced an increase in the TR of NWR in the PSP group while TST of NWR increased in both PSP and PD.

CONCLUSIONS

Our neurophysiological findings identify a facilitation of nociceptive processing in PSP that is broadly similar to that observed in MSA and PD. Specific peculiarities have emerged for PSP.

SIGNIFICANCE

Our data advance the knowledge of the neurophysiology of nociception in the advanced phases of parkinsonian syndromes and on the role of dopaminergic pathways in the control on pain processing.

Pain in Neurodegenerative Disease: Current Knowledge and Future Perspectives

Neurodegenerative diseases are going to increase as the life expectancy is getting longer. The management of neurodegenerative diseases such as Alzheimer's disease (AD) and other dementias, Parkinson's disease (PD) and PD related disorders, motor neuron diseases (MND), Huntington's disease (HD), spinocerebellar ataxia (SCA), and spinal muscular atrophy (SMA), is mainly addressed to motor and cognitive impairment, with special care to vital functions as breathing and feeding. Many of these patients complain of painful symptoms though their origin is variable, and their presence is frequently not considered in the treatment guidelines, leaving their management to the decision of the clinicians alone. However, studies focusing on pain frequency in such disorders suggest a high prevalence of pain in selected populations from 38 to 75% in AD, 40% to 86% in PD, and 19 to 85% in MND. The methods of pain assessment vary between studies so the type of pain has been rarely reported. However, a prevalent nonneuropathic origin of pain emerged for MND and PD. In AD, no data on pain features are available. No controlled therapeutic trials and guidelines are currently available. Given the relevance of pain in neurodegenerative disorders, the comprehensive understanding of mechanisms and predisposing factors, the application and validation of specific scales, and new specific therapeutic trials are needed.

Pain in multiple system atrophy and progressive supranuclear palsy compared to Parkinson's disease

BACKGROUND

Pain is a common nonmotor symptom in Parkinson's disease (PD). The pathophysiology of pain in PD is not well understood. Pain characteristics have rarely been studied in atypical parkinsonian disorders such as Multiple System Atrophy (MSA) and Progressive Supranuclear Palsy (PSP).

AIM OF THE STUDY

We aimed to evaluate pain intensity, location, and associated symptoms in atypical parkinsonian disorders compared to PD.

METHODS

Twenty-one patients with MSA, 16 patients with PSP, and 65 patients with PD were screened for pain using question 1.9 of the MDS-UPDRS. Pain intensity was quantified using the short form McGill Pain Questionnaire (SFMPQ). Pain locations were documented. Motor disability was measured using UPDRS-III. Affective symptoms were assessed using the Hospital Anxiety and Depression Scale (HADS).

RESULTS

Pain was significantly more common and more severe in PD and MSA compared to PSP (P < 0.01). Pain locations were similar with limb pain being the most common followed by neck and back pain. Pain intensity correlated with HADS scores but not motor severity.

CONCLUSIONS

Pain is more common and more intense in PD and MSA than PSP. Differences in distribution of neurodegenerative pathologies may underlie these differential pain profiles.