The perception of affective touch in Parkinson's disease and its relation to small fibre neuropathy.

Affective touch sensation is conducted by a sub-class of C-fibres in hairy skin known as C-Tactile (CT) afferents. CT afferents respond maximally to gentle skin stroking at velocities between 1 and 10 cm/s. Parkinson's disease (PD) is characterised by markedly reduced cutaneous C-fibres. It is not known if affective touch perception is influenced by C-fibre density and if affective touch is impaired in PD compared to healthy controls. We predicted that perceived pleasantness to gentle stroking in PD would correlate with C-afferent density and that affective touch perception would be impaired in PD compared to healthy controls. Twenty-four PD patients and 27 control subjects rated the pleasantness of brush stroking at an optimum CT stimulation velocity (3 cm/s) and two sub-optimal velocities (0.3 and 30 cm/s). PD patients underwent quantification of C-fibre density using skin biopsies and corneal confocal microscopy. All participants rated a stroking velocity of 3 cm/s as the most pleasant with significantly lower ratings for 0.3 and 30 cm/s. There was a significant positive correlation between C-fibre density and pleasantness ratings at 3 and 30 cm/s but not 0.3 cm/s. Mean pleasantness ratings were consistently higher in PD patients compared to control subjects across all three velocities. This study shows that perceived pleasantness to gentle touch correlates significantly with C-fibre density in PD. The higher perceived pleasantness in PD patients compared to controls suggests central sensitisation to peripheral inputs, which may have been enhanced by dopamine therapy.

Glycine receptor antibodies and coeliac disease-related neurological dysfunction.

Gluten sensitivity can manifest with a spectrum of neurological dysfunction including ataxia, encephalopathy and neuropathy with or without associated coeliac disease (CD). Gluten sensitivity can also present with central nervous system (CNS) hyperexcitability and cortical myoclonus which is often accompanied with refractory CD. CNS hyperexcitability can also be associated with Glutamic Acid Decarboxylase (GAD) antibodies or much less commonly with Glycine Receptor Antibodies (GlyR-Abs) but the direct pathogenic roles of these antibodies remain debatable. We have previously reported a link between gluten sensitivity and anti-GAD associated ataxia which improves with the adoption of gluten-free diet. It is unclear if a similar link exists between gluten driven CNS hyperexcitability and the presence of GlyR-Abs. We report two cases of CD presenting with CNS hyperexcitability and associated GlyR-Abs. Apart from ataxia and cortical myoclonus, one patient had refractory CD and died from enteropathy-associated T-cell lymphoma. The other patient not only improved with strict gluten-free diet but also showed serological elimination of circulating GlyR-Abs. We conclude that there is an interaction between gluten sensitivity and GlyR-Abs-associated CNS hyperexcitability and in such patients gluten-free diet is an important therapeutic intervention. The elimination of GlyR-Abs by the adoption of gluten free diet suggests that these antibodies may represent an epiphenomenon rather than being directly implicated in the pathogenesis.

Autologous haematopoietic stem cell transplantation for refractory stiff-person syndrome: the UK experience.

Stiff Person Syndrome (SPS) is a rare immune-mediated disabling neurological disorder characterised by muscle spasms and high GAD antibodies. There are only a few case reports of autologous haematopoietic stem cell transplantation (auto-HSCT) as a treatment for SPS. OBJECTIVE: To describe the UK experience of treating refractory SPS with auto-HSCT. METHODS: Between 2015 and 2019, 10 patients with SPS were referred to our institution for consideration of auto-HSCT. Eight patients were deemed suitable for autograft and four were treated. Of the treated patients, three had classical SPS and one had the progressive encephalomyelitis with rigidity and myoclonus variant. All patients were significantly disabled and had failed conventional immunosuppressive therapy. Patients were mobilised with Cyclophosphamide (Cy) 2 g/m2 + G-CSF and conditioned with Cy 200 mg/kg + ATG followed by auto-HSCT. RESULTS: Despite their significantly reduced performance status, all patients tolerated the procedure with no unexpected toxicities. Following autograft, all patients improved symptomatically and stopped all forms of immunosuppressive therapies. Two patients were able to ambulate independently from being wheelchair dependent. One patient's walking distance improved from 300 meters to 5 miles and one patient's ambulation improved from being confined to a wheelchair to be able to walk with a frame. Two patients became seronegative for anti-GAD antibodies and normalised their neurophysiological abnormalities. CONCLUSIONS: Auto-HSCT is an intensive but well tolerated and effective treatment option for patients with SPS refractory to conventional immunotherapy. Further work is warranted to optimise patient selection and establish the efficacy, long-term safety, and cost-effectiveness of this treatment.

Corneal confocal microscopy detects small fibre neurodegeneration in Parkinson's disease using automated analysis.

We studied the utility of corneal confocal microscopy (CCM) in detecting a reduction in corneal nerve parameters in a large cohort of patients with Parkinson's disease (PD) compared to controls using a fully automated potentially scalable method of analysis. We also assessed if CCM parameters are related to the severity and sub-type of PD. 98 participants with PD and 26 healthy controls underwent CCM with automated corneal nerve quantification, MDS-UPDRS III, Hoehn and Yahr scale, Montreal Cognitive Assessment, Parkinson's Disease Questionnaire-39 and PD subtype assessment. Corneal nerve fibre density (mean difference: - 5.00 no/mm2, 95% confidence interval (CI) [- 7.89, - 2.12], p = 0.001), corneal nerve branch density (mean difference: - 10.71 no/mm2, 95% CI [- 16.93, - 4.48], p = 0.003), corneal total branch density (mean difference: - 14.75 no/mm2, 95% CI [- 23.58, - 5.92], p = 0.002), and corneal nerve fibre length (mean difference: - 2.57 mm/mm2, 95% CI [- 4.02, - 1.12], p = 0.001) were significantly lower in PD participants compared to controls. There was no correlation between corneal nerve parameters and duration, severity or subtype of PD, cognitive function or quality of life. CCM with automated corneal nerve analysis identifies nerve fibre damage and may act as a biomarker for neurodegeneration in PD.

Increased Intraepidermal Nerve Fiber Degeneration and Impaired Regeneration Relate to Symptoms and Deficits in Parkinson's Disease.

Background: Previous studies have shown cutaneous small fiber pathology in patients with Parkinson's disease (PD). These studies have focused on nerve degeneration, but recent reports suggest that nerve regeneration may also be important in PD pathology. Objective: To establish the extent of intraepidermal nerve fiber (IENF) degeneration and regeneration and its relationship to clinical and neurological deficits in Parkinson's disease (PD). Methods: Twenty-three PD patients and 10 age-matched controls underwent skin biopsy and assessment of somatic and autonomic symptoms and deficits. We have assessed Intraepidermal Nerve Fiber Density (IENFD) using standard PGP9.5 staining and GAP-43 to assess Mean Axonal Length (MAL) and Intraepidermal Total Nerve Fiber Length (IETNFL). Results: IENFD (p < 0.0001), MAL (p < 0.0001), IETNFL/Area (p = 0.009), and IETNFL/Length (p = 0.04) were significantly reduced in patients with PD compared to controls. IENFD correlated significantly with disease duration (p = 0.03), cumulative levodopa dose (p = 0.02), Unified Parkinson's Disease Rating Scale, Part III (UPDRS-III) (p = 0.01), Schwab and England Activities of Daily Living (ADL) (p = 0.03), NSP (p = 0.03), and 30:15 ratio (p = 0.03). IETNFL/Area correlated with the Autonomic Scale for Outcomes in Parkinson's Disease (SCOPA-AUT) (p = 0.03) and Diabetic Neuropathy Symptom score (DNS) (p = 0.04) and IETNFL/Length correlated with DNS (p = 0.03). MAL correlated with SCOPA-AUT (p = 0.01), DNS (p = 0.02), and DB-HRV (p = 0.02). Conclusion: Increased IENF degeneration and impaired regeneration correlates with somatic and autonomic symptoms and deficits in patients with PD.

Small Fibre Neuropathy in Parkinson's Disease: Comparison of Skin Biopsies from the More Affected and Less Affected Sides.

We assessed small nerve fibre degeneration and regeneration in more and less affected sides in Parkinson's disease (PD). Bilateral skin biopsies from 23 PD patients were immunostained for PGP9.5 for Intraepidermal Nerve Fibre Density (IENFD) and GAP-43 for mean axonal length (MAL), total epidermal (TNFL) and subepidermal nerve fibre length (SKTNFL). IENFD (p < 0.001) and SKTNFL (p < 0.001) were lower, whilst MAL (p < 0.001) and TNFL (p < 0.05) were higher in more affected versus less affected side. These results suggest increased small nerve fibre degeneration accompanied by enhanced nerve regeneration on the side more affected by PD and GAP-43 usefulness in skin biopsy assessment.

Globus pallidal deep brain stimulation for Tourette syndrome: Effects on cognitive function.

INTRODUCTION: In a double-blind randomized crossover trial, we previously established that bilateral deep brain stimulation of the anteromedial globus pallidus internus (GPiam-DBS) is effective in significantly reducing tic severity in patients with refractory Tourette syndrome (TS). Here, we report the effects of bilateral GPiam-DBS on cognitive function in 11 of the 13 patients who had participated in our double-blind cross-over trial of GPi-DBS. METHODS: Patients were assessed at baseline (4 weeks prior to surgery) and at the end of each of the three-month blinded periods, with stimulation either ON or OFF. The patients were evaluated on tests of memory (California Verbal Learning Test-II (CVLT-II); Corsi blocks; Short Recognition Memory for Faces), executive function (D-KEFS Stroop color-word interference, verbal fluency, Trail-making test, Hayling Sentence Completion test), and attention (Paced Auditory Serial Addition Test, Numbers and Letters Test). RESULTS: GPiam-DBS did not produce any significant change in global cognition. Relative to pre-operative baseline assessment verbal episodic memory on the CVLT-II and set-shifting on the Trail-making Test were improved with DBS OFF. Performance on the cognitive tests were not different with DBS ON versus DBS OFF. GPiam-DBS did not alter aspects of cognition that are impaired in TS such as inhibition on the Stroop interference task or the Hayling Sentence Completion test. CONCLUSIONS: This study extends previous findings providing data showing that GPiam-DBS does not adversely affect cognitive domains such as memory, executive function, verbal fluency, attention, psychomotor speed, and information processing. These results indicate that GPiam-DBS does not produce any cognitive deficits in TS.

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.

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.

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

UNLABELLED: 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.

Bilateral globus pallidus stimulation for severe Tourette's syndrome: a double-blind, randomised crossover trial.

BACKGROUND: Deep brain stimulation (DBS) has been proposed as a treatment option for severe Tourette's syndrome on the basis of findings from open-label series and small double-blind trials. We aimed to further assess the safety and efficacy of bilateral globus pallidus internus (GPi) DBS in patient's with severe Tourette's syndrome. METHODS: In a randomised, double-blind, crossover trial, we recruited eligible patients (severe medically refractory Tourette's syndrome, age ≥20 years) from two clinics for tertiary movement disorders in the UK. Enrolled patients received surgery for GPi DBS and then were randomly assigned in a 1:1 ratio (computer-generated pairwise randomisation according to order of enrolment) to receive either stimulation on-first or stimulation off-first for 3 months, followed by a switch to the opposite condition for a further 3 month period. Patients and rating clinicians were masked to treatment allocation; an unmasked clinician was responsible for programming the stimulation. The primary endpoint was difference in Yale Global Tic Severity Scale (YGTSS) total score between the two blinded conditions, assessed with repeated measures ANOVA, in all patients who completed assessments during both blinded periods. After the end of the blinded crossover phase, all patients were offered continued DBS and continued to have open-label stimulation adjustments and objective assessments of tic severity until database lock 1 month after the final patient's final trial-related visit. This trial is registered with ClinicalTrials.gov, number NCT01647269. FINDINGS: Between Nov 5, 2009, and Oct 16, 2013, we enrolled 15 patients (11 men, four women; mean age 34·7 years [SD 10·0]). 14 patients were randomly assigned and 13 completed assessments in both blinded periods (seven in the on-first group, six in the off-first group). Mean YGTSS total score in these 13 patients was 87·9 (SD 9·2) at baseline, 80·7 (SD 12·0) for the off-stimulation period, and 68·3 (SD 18·6) for the on-stimulation period. Pairwise comparisons in YGTSS total scores after Bonferroni correction were significantly lower at the end of the on-stimulation period compared with the off-stimulation period, with a mean improvement of 12·4 points (95% CI 0·1-24·7, p=0·048), equivalent to a difference of 15·3% (95% CI 5·3-25·3). All 15 patients received stimulation in the open-label phase. Overall, three serious adverse events occurred (two infections in DBS hardware at 2 and 7 weeks postoperatively, and one episode of deep-brain-stimulation-induced hypomania during the blinded on-stimulation period); all three resolved with treatment. INTERPRETATION: GPi stimulation led to a significant improvement in tic severity, with an overall acceptable safety profile. Future research should concentrate on identifying the most effective target for DBS to control both tics and associated comorbidities, and further clarify factors that predict individual patient response. FUNDING: UK National Health Service.

Randomized clinical trial of topiramate for levodopa-induced dyskinesia in Parkinson's disease.

BACKGROUND: The antiepileptic drug topiramate reduces levodopa-induced dyskinesia without exacerbating parkinsonism in animal models. We report a randomized, double-blind, placebo-controlled crossover trial in patients with Parkinson's disease and levodopa-induced dyskinesia. METHODS: Fifteen patients with Parkinson's disease and stable levodopa-induced dyskinesia were enrolled into the study, of whom 13 were randomized to topiramate or placebo. The study medication was titrated to 100 mg/day over four weeks, and assessments were carried out after a further two weeks. Dyskinesia severity assessed by a blinded rater from video recordings was the primary outcome measure. RESULTS: Seven patients (mean age 58.9 ± 12.8 years) completed the study. Patients taking topiramate vs. placebo showed a significant increase in dyskinesia severity compared to baseline (Wilcoxon signed rank test, P = 0.043). Five patients withdrew from the study whilst taking topiramate due to adverse effects. CONCLUSIONS: Topiramate tended to worsen dyskinesia in patients with Parkinson's disease, and was poorly tolerated.