Generalized Dystonia Due to a Pathogenic THAP1 Variant Showing Sustained Response to Globus Pallidus Deep Brain Stimulation

A 21-year-old woman of south Asian origin presented with cervical dystonia which had progressed over the previous three years. Her symptoms started as writer's cramp since the age of seven years. She did not respond to medications and needed botulinum toxin injection for generalised dystonia. Subsequent whole genome sequencing revealed a likely pathogenic c.98G>A p.(Cys33Tyr) heterozygous variant in the THAP1 gene. She underwent bilateral posteroventral globus pallidus interna (GPi) deep brain stimulation (Medtronic Activa PC) implantation at the age of thirty-one years. She responded well to the deep brain stimulation even after more than 8 years post-surgery though she needs botulinum toxin injection for her cervical dystonia.

Altered Pain Processing Associated with Administration of Dopamine Agonist and Antagonist in Healthy Volunteers

Striatal dopamine dysfunction is associated with the altered top-down modulation of pain processing. The dopamine D2-like receptor family is a potential substrate for such effects due to its primary expression in the striatum, but evidence for this is currently lacking. Here, we investigated the effect of pharmacologically manipulating striatal dopamine D2 receptor activity on the anticipation and perception of acute pain stimuli in humans. Participants received visual cues that induced either certain or uncertain anticipation of two pain intensity levels delivered via a CO₂ laser. Rating of the pain intensity and unpleasantness was recorded. Brain activity was recorded with EEG and analysed via source localisation to investigate neural activity during the anticipation and receipt of pain. Participants completed the experiment under three conditions, control (Sodium Chloride), D2 receptor agonist (Cabergoline), and D2 receptor antagonist (Amisulpride), in a repeated-measures, triple-crossover, double-blind study. The antagonist reduced an individuals’ ability to distinguish between low and high pain following uncertain anticipation. The EEG source localisation showed that the agonist and antagonist reduced neural activations in specific brain regions associated with the sensory integration of salient stimuli during the anticipation and receipt of pain. During anticipation, the agonist reduced activity in the right mid-temporal region and the right angular gyrus, whilst the antagonist reduced activity within the right postcentral, right mid-temporal, and right inferior parietal regions. In comparison to control, the antagonist reduced activity within the insula during the receipt of pain, a key structure involved in the integration of the sensory and affective aspects of pain. Pain sensitivity and unpleasantness were not changed by D2R modulation. Our results support the notion that D2 receptor neurotransmission has a role in the top-down modulation of pain.

Parkinson's-adapted cognitive stimulation therapy: a pilot randomized controlled clinical trial

Cognitive stimulation therapy (CST) is widely used with people with dementia, but there is no evidence of its efficacy in mild cognitive impairment or dementia in Parkinson's disease (PD-MCI; PDD) or dementia with Lewy bodies (DLB). We aimed to explore the impact of 'CST-PD', which is home-based, individualized CST adapted for this population. In a single-blind, randomized controlled exploratory pilot trial (RCT), we randomized 76 participant-dyads [PD-MCI (n = 15), PDD (n = 40), DLB (n = 21) and their care partners] to CST-PD or treatment as usual (TAU). CST-PD involves home-based cognitively stimulating and engaging activities delivered by a trained care partner. Exploratory outcomes at 12 weeks included cognition (Addenbrooke's Cognitive Evaluation; ACE-III), neuropsychiatric symptoms and function. In care partners, we assessed burden, stress and general health status. Relationship quality and quality of life were assessed in both dyad members. At 12 weeks, the ACE-III showed a nonstatistically significant improvement in the CST-PD group compared with the TAU group, although neuropsychiatric symptoms increased significantly in the former. In contrast, care partners' quality of life (d = 0.16) and relationship quality ('satisfaction', d = 0.01; 'positive interaction', d = 0.55) improved significantly in the CST-PD group, and care burden (d = 0.16) and stress (d = 0.05) were significantly lower. Qualitative findings in the CST-PD recipients revealed positive 'in the moment' responses to the intervention, supporting the quantitative results. In conclusion, care-partner-delivered CST-PD may improve a range of care-partner outcomes that are important in supporting home-based care. A full-scale follow-up RCT to evaluate clinical and cost effectiveness is warranted.

Parkinson's-adapted cognitive stimulation therapy: feasibility and acceptability in Lewy body spectrum disorders

BACKGROUND

Drug-based therapeutic approaches for Parkinson's disease dementia (PDD) and dementia with Lewy bodies (DLB) are moderately effective and not always tolerated. Tailoring psychosocial approaches in PDD and DLB may offer additional support and improve outcomes. We adapted home-based, care partner-delivered Cognitive Stimulation Therapy (CST) for individuals with PDD or DLB and their care partners (CST-PD).

OBJECTIVES

To evaluate the feasibility, acceptability, and tolerability of CST-PD.

METHODS

This randomised controlled trial used mixed methods, including a process evaluation. People with PDD, DLB or mild cognitive impairment in PD (PD-MCI) and their care partners were randomised to 12 weeks of treatment as usual (TAU) or CST-PD. Outcomes were feasibility of the study conduct (i.e., recruitment, retention rate) and acceptability and tolerability of the intervention. Measures included rating scales, researcher field notes, therapy diaries, and exploratory clinical and care partner efficacy measures.

RESULTS

The recruitment target was met with 76 consenting participant-dyads. Retention in both arms was high at over 70%. More than 90% of dyads undertook discrete sessions greater than 20 min duration, but the average number of sessions completed was lower than the recommended dose. Acceptability ratings (i.e., interest, motivation and sense of achievement) of the intervention were high. Participants reported no serious adverse events related to the intervention.

CONCLUSIONS

The field of psychosocial interventions for PDD and DLB is newly emerging, and we demonstrated that this type of intervention is acceptable and well tolerated. Evaluating its clinical effectiveness in a full-scale randomized controlled clinical trial is warranted.

TRIAL REGISTRATION NUMBER

The trial is a psychosocial intervention with an allocated ISRCTN number 11455062.

A detailed clinical study of pain in 1957 participants with early/moderate Parkinson's disease

INTRODUCTION

The causes of pain in early/moderate Parkinson's disease (PD) are not well understood. Although peripheral factors such as rigidity, reduced joint movements and poor posture may contribute towards the development of pain, central mechanisms including altered nociceptive processing may also be involved.

METHODS

We performed a large clinical study to investigate potential factors contributing towards pain in early/moderate PD. We recruited 1957 PD participants who had detailed assessments of pain, motor and non-motor symptoms. The King's Parkinson's Pain scale was used to quantify different subtypes of pain.

RESULTS

85% of participants reported pain (42% with moderate to severe pain). Pain influenced quality of life more than motor symptoms in a multiple regression model. Factors predicting overall pain severity included affective symptoms, autonomic symptoms, motor complications, female gender and younger age, but not motor impairment or disease duration. There was negligible correlation between the severity of motor impairment and the severity of musculoskeletal or dystonic pain as well as between the severity of OFF period motor problems and the severity of OFF period pain or OFF period dystonic pain. Features of central sensitization, including allodynia and altered pain sensation were common in this population. The use of drugs targeting central pain was very low.

CONCLUSIONS

Pain in early/moderate PD cannot be explained by peripheral factors. Central causes may play a much more important role than previously considered. These results should lead to a major shift in the investigation and management of this common and disabling symptom.

Psychosocial therapy for Parkinson's-related dementia: study protocol for the INVEST randomised controlled trial

INTRODUCTION

Parkinson's disease (PD) with mild cognitive impairment (MCI-PD) or dementia (PDD) and dementia with Lewy bodies (DLB) are characterised by motor and 'non-motor' symptoms which impact on quality of life. Treatment options are generally limited to pharmacological approaches. We developed a psychosocial intervention to improve cognition, quality of life and companion burden for people with MCI-PD, PDD or DLB. Here, we describe the protocol for a single-blind randomised controlled trial to assess feasibility, acceptability and tolerability of the intervention and to evaluate treatment implementation. The interaction among the intervention and selected outcome measures and the efficacy of this intervention in improving cognition for people with MCI-PD, PDD or DLB will also be explored.

METHODS AND ANALYSIS

Dyads will be randomised into two treatment arms to receive either 'treatment as usual' (TAU) or cognitive stimulation therapy specifically adapted for Parkinson's-related dementias (CST-PD), involving 30 min sessions delivered at home by the study companion three times per week over 10 weeks. A mixed-methods approach will be used to collect data on the operational aspects of the trial and treatment implementation. This will involve diary keeping, telephone follow-ups, dyad checklists and researcher ratings. Analysis will include descriptive statistics summarising recruitment, acceptability and tolerance of the intervention, and treatment implementation. To pilot an outcome measure of efficacy, we will undertake an inferential analysis to test our hypothesis that compared with TAU, CST-PD improves cognition. Qualitative approaches using thematic analysis will also be applied. Our findings will inform a larger definitive trial.

ETHICS AND DISSEMINATION

Ethical opinion was granted (REC reference: 15/YH/0531). Findings will be published in peer-reviewed journals and at conferences. We will prepare reports for dissemination by organisations involved with PD and dementia.

TRIAL REGISTRATION NUMBER

ISRCTN (ISRCTN11455062).

Dystonia Associated with Idiopathic Slow Orthostatic Tremor

BACKGROUND

We aimed to characterize the clinical and electrophysiological features of patients with slow orthostatic tremor.

CASE REPORT

The clinical and neurophysiological data of patients referred for lower limb tremor on standing were reviewed. Patients with symptomatic or primary orthostatic tremor were excluded. Eight patients were identified with idiopathic slow 4-8 Hz orthostatic tremor, which was associated with tremor and dystonia in cervical and upper limb musculature. Coherence analysis in two patients showed findings different to those seen in primary orthostatic tremor.

DISCUSSION

Slow orthostatic tremor may be associated with dystonia and dystonic tremor.

Dystonia Associated with Idiopathic Slow Orthostatic Tremor

BACKGROUND

We aimed to characterize the clinical and electrophysiological features of patients with slow orthostatic tremor.

CASE REPORT

The clinical and neurophysiological data of patients referred for lower limb tremor on standing were reviewed. Patients with symptomatic or primary orthostatic tremor were excluded. Eight patients were identified with idiopathic slow 4-8 Hz orthostatic tremor, which was associated with tremor and dystonia in cervical and upper limb musculature. Coherence analysis in two patients showed findings different to those seen in primary orthostatic tremor.

DISCUSSION

Slow orthostatic tremor may be associated with dystonia and dystonic tremor.

Small fiber neuropathy in Parkinson's disease: A clinical, pathological and corneal confocal microscopy study

Autonomic and somatic denervation is well established in Parkinson's disease (PD).

Objectives

(1) To determine whether corneal confocal microscopy (CCM) can non-invasively demonstrate small nerve fiber damage in PD. (2) To identify relationships between corneal nerve parameters, intraepidermal nerve fiber density (IENFD) and clinical features of PD.

Methods

Twenty-six PD patients and 26 controls underwent CCM of both eyes. 24/26 PD patients and 10/26 controls underwent skin biopsies from the dorsa of both feet. PD patients underwent assessment of parasympathetic function [deep breathing heart rate variability (DB-HRV)], autonomic symptoms [scale for outcomes in Parkinson's disease – autonomic symptoms (SCOPA-AUT)], motor symptoms [UPDRS-III “ON”] and cumulative Levodopa dose.

Results

PD patients had significantly reduced corneal nerve fiber density (CNFD) with increased corneal nerve branch density (CNBD) and corneal nerve fiber length (CNFL) compared to controls. CNBD and CNFL but not CNFD correlated inversely with UPDRS-III and SCOPA-AUT. All CCM parameters correlated strongly with DB-HRV. There was no correlation between CCM parameters and disease duration, cumulative Levodopa dose or pain. IENFD was significantly reduced in PD compared to controls and correlated with CNFD and UPDRS-III. However, unlike CCM measures, IENFD correlated with disease duration and cumulative Levodopa dose but not with autonomic dysfunction.

Conclusion

CCM identifies corneal nerve fiber pathology, which correlates with autonomic symptoms, parasympathetic deficits and motor scores in patients with PD. IENFD is also reduced and correlates with CNFD and motor symptoms but not parasympathetic deficits, indicating it detects different aspects of peripheral nerve pathology in PD.

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Peripheral denervation is established in Parkinson's disease (PD) on skin biopsies.

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Corneal confocal microscopy (CCM) can non-invasively visualize corneal nerves.

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We have shown significant corneal denervation in PD compared to controls using CCM.

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Corneal denervation relates to skin denervation and parasympathetic dysfunction.

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.

Prominent Lower-Limb Involvement in a Family with Myoclonus-Dystonia

We report on a large family with myoclonus-dystonia resulting from an epsilon-sarcoglycan mutation, with prominent early and late lower-limb involvement. The proband's condition has evolved to include marked lower-limb dystonia and dystonic gait impairment in the fourth decade. Other family members had evidence of prominent lower-limb involvement at presentation or a more typical phenotype of axial and upper-limb myoclonus and dystonia. Prominent lower-limb involvement developing late in the disease course is an atypical feature and exemplifies the wide phenotypic heterogeneity observed in people with myoclonus-dystonia.

Topiramate reduces levodopa-induced dyskinesia in the MPTP-lesioned marmoset model of Parkinson's disease

Overactive AMPA receptor-mediated transmission may be involved in the pathogenesis of levodopa-induced dyskinesia. The mechanism of action of the anticonvulsant drug topiramate involves attenuation of AMPA receptor-mediated transmission. In this study, the potential antidyskinetic action of topiramate was examined in the MPTP-lesioned marmoset model of Parkinson's disease and levodopa-induced dyskinesia. Topiramate significantly reduced levodopa-induced dyskinesia, without affecting the antiparkinsonian action of levodopa. Topiramate represents an exciting potential novel therapeutic approach to levodopa-induced dyskinesia in patients with Parkinson's disease.

Selective blockade of D3 dopamine receptors enhances the anti-parkinsonian properties of ropinirole and levodopa in the MPTP-lesioned primate

To date, the lack of highly selective antagonists at the dopamine D(3) receptor has hampered clarification of their involvement in the actions of currently used therapies in Parkinson's disease. However, the novel benzopyranopyrrole, S33084, displays greater than 100-fold selectivity as an antagonist for D(3) versus D(2) receptors and all other sites tested. S33084 was administered to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-lesioned marmosets previously primed with levodopa to elicit dyskinesia. Administered alone, S33084 exerted a modest, but significant, anti-parkinsonian effect without provoking dyskinesia. At low D(3)-selective doses (0.16 and 0.64 mg/kg), S33084 potentiated, though to different extents and in qualitatively different ways, the anti-parkinsonian actions of both ropinirole and levodopa. At these doses, S33084 did not significantly modify levodopa-induced or ropinirole-induced dyskinesia. These data suggest that ropinirole and levodopa do not exert their anti-parkinsonian or pro-dyskinetic actions via D(3) receptor stimulation. Indeed, stimulation of D(3) receptors may be detrimental to the anti-parkinsonian properties of D(2)/D(3) agonists. Selectivity for stimulation of D(2), over D(3), receptors may therefore be a beneficial property of dopamine receptor agonists in management of motor symptoms of Parkinson's disease patients with established dyskinesia.

Striatal AMPA receptor binding is unaltered in the MPTP-lesioned macaque model of Parkinson's disease and dyskinesia

Long-term levodopa or dopamine agonist treatment in the MPTP-lesioned primate model of Parkinson's disease elicits dyskinesia, which is phenotypically similar to levodopa-induced dyskinesia in patients with Parkinson's disease. AMPA receptor antagonists have previously been shown to have both anti-parkinsonian and anti-dyskinetic actions in MPTP-lesioned primates, suggesting that AMPA receptor transmission is functionally overactive under these conditions. In this study, we investigated the level of striatal AMPA receptor binding in the MPTP lesioned primate using the selective AMPA ligand (3)H-(S)-5-fluorowillardiine. AMPA receptor binding was studied in non-parkinsonian, non-dyskinetic parkinsonian, and dyskinetic macaques. Striatal AMPA receptor binding was not different in any of the treatment groups (P > 0.05). Although AMPA receptor-mediated transmission is functionally overactive in Parkinson's disease and dyskinesia, changes in striatal AMPA receptor levels are not likely to be the cause of such movement disorders.

Striatal Cannabinoid CB1 Receptor mRNA Expression Is Decreased in the Reserpine-Treated Rat Model of Parkinson's Disease

High levels of both endocannabinoids and endocannabinoid receptors are present in the basal ganglia. Attention has recently focused on the role of endocannabinoids in the control of movement and in movement disorders of basal ganglia origin such as Parkinson's disease. We investigated CB1 cannabinoid receptor mRNA expression in the reserpine-treated rat model of Parkinson's disease using in situ hybridization. Reserpine treatment caused a topographically organized reduction in CB1 receptor mRNA expression in the striatum (ranging from 11.6% medially to 53.6% laterally and dorsally). No change in CB1 receptor mRNA expression was observed in the cerebral cortex or septum. This reduction in CB1 receptor mRNA expression may be secondary to increased endocannabinoid stimulation of the receptor as increased basal ganglia endocannabinoid levels have been shown to occur in this model of Parkinson's disease. The data support the idea that cannabinoid receptor antagonists may provide a useful treatment for the symptoms of Parkinson's disease.