Pupillary autonomic dysfunction in multiple system atrophy and Parkinson's disease: an assessment by eye-drop tests

Pupil light reflex dynamics in Parkinson's disease

Introduction

Visual disturbance is common symptom in Parkinson's disease (PD), and defective pupil light reflex (PLR) is an anticipated contributing factor that may be associated to the presence of autonomic dysfunction, which is a common non-motor feature of PD. Studies investigating the intercorrelation between PLR and dysautonomia in PD are limited.

Methods

The aim of this study was to investigate differences of PLR parameters, measured by eye-tracker, between patients with PD, with and without signs of dysautonomia, and healthy controls (HC). In total, 43 HC and 50 patients with PD were recruited and PLR parameters were measured with Tobii Pro Spectrum, during a long (1,000 ms) and a short (100 ms) light stimulus. Presence of orthostatic hypotension (OH) was used as proxy marker of dysautonomia. Linear mixed-effects model and non-parametric comparative statistics were applied to investigate differences among groups.

Results

Peak constriction velocity was slower in PD compared with HC, after adjustment for age and sex in the mixed model, and the difference was greater in the subgroup of PD with OH (unadjusted). Dilation amplitude and velocity were also gradually slower in HC vs. PD without OH vs. PD with OH (unadjusted for confounders). In the mixed model, age was significant predictor of dilation response.

Discussion

Our results support previous observations on defective PLR in PD, evaluated with eye-tracker, and show a possible association with autonomic dysfunction. Further studies with more patients and rigorous evaluation of autonomic dysfunction are needed to validate these findings.

Eye tracking identifies biomarkers in α-synucleinopathies versus progressive supranuclear palsy

Objectives

This study (1) describes and compares saccade and pupil abnormalities in patients with manifest alpha-synucleinopathies (αSYN: Parkinson’s disease (PD), Multiple System Atrophy (MSA)) and a tauopathy (progressive supranuclear palsy (PSP)); (2) determines whether patients with rapid-eye-movement sleep behaviour disorder (RBD), a prodromal stage of αSYN, already have abnormal responses that may indicate a risk for developing PD or MSA.

Methods

Ninety (46 RBD, 27 PD, 17 MSA) patients with an αSYN, 10 PSP patients, and 132 healthy age-matched controls (CTRL) were examined with a 10-min video-based eye-tracking task (Free Viewing). Participants were free to look anywhere on the screen while saccade and pupil behaviours were measured.

Results

PD, MSA, and PSP spent more time fixating the centre of the screen than CTRL. All patient groups made fewer macro-saccades (> 2^◦ amplitude) with smaller amplitude than CTRL. Saccade frequency was greater in RBD than in other patients. Following clip change, saccades were temporarily suppressed, then rebounded at a slower pace than CTRL in all patient groups. RBD had distinct, although discrete saccade abnormalities that were more marked in PD, MSA, and even more in PSP. The vertical saccade rate was reduced in all patients and decreased most in PSP. Clip changes produced large increases or decreases in screen luminance requiring pupil constriction or dilation, respectively. PSP elicited smaller pupil constriction/dilation responses than CTRL, while MSA elicited the opposite.

Conclusion

RBD patients already have discrete but less pronounced saccade abnormalities than PD and MSA patients. Vertical gaze palsy and altered pupil control differentiate PSP from αSYN.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00415-022-11136-5.

An update on MSA: premotor and non-motor features open a window of opportunities for early diagnosis and intervention

In this review, we describe the wide clinical spectrum of features that can be seen in multiple system atrophy (MSA) with a focus on the premotor phase and the non-motor symptoms providing an up-to-date overview of the current understanding in this fast-growing field. First, we highlight the non-motor features at disease onset when MSA can be indistinguishable from pure autonomic failure or other chronic neurodegenerative conditions. We describe the progression of clinical features to aid the diagnosis of MSA early in the disease course. We go on to describe the levels of diagnostic certainty and we discuss MSA subtypes that do not fit into the current diagnostic criteria, highlighting the complexity of the disease as well as the need for revised diagnostic tools. Second, we describe the pathology, clinical description, and investigations of cardiovascular autonomic failure, urogenital and sexual dysfunction, orthostatic hypotension, and respiratory and REM-sleep behavior disorders, which may precede the motor presentation by months or years. Their presence at presentation, even in the absence of ataxia and parkinsonism, should be regarded as highly suggestive of the premotor phase of MSA. Finally, we discuss how the recognition of the broader spectrum of clinical features of MSA and especially the non-motor features at disease onset represent a window of opportunity for disease-modifying interventions.

Pupillary dysfunction of multiple system atrophy: Dynamic pupillometric findings and clinical correlations

INTRODUCTION

Although autonomic dysfunction is the prominent clinical feature in multiple system atrophy (MSA), little is known about the pupillary autonomic aspect of MSA. We aimed to evaluate pupillary autonomic function in MSA patients using dynamic pupillometry, which can quantify the pupillary light reflex.

METHODS

Dynamic pupillometry parameters were compared in 21 MSA patients and 21 healthy controls. Pupillometric parameters were correlated with total Unified Multiple System Atrophy Rating Scale (UMSARS) scores and autonomic symptom severity.

RESULTS

Average constriction (p = 0.034) and dilation (p = 0.003) velocities were significantly slowed in MSA patients compared with controls. Total UMSARS correlated with the average constriction (r = -0.527, p = 0.017) and maximum constriction (r = -0.658, p = 0.003) velocities. Autonomic symptom severity correlated with average constriction (r = -0.544, p = 0.013), maximum constriction (r = -0.607, p = 0.005) and average dilation (r = -0.499, p = 0.025) velocities.

CONCLUSION

Dynamic pupillometry may provide useful information about pupillary autonomic dysfunction, which correlated with the clinical severity, in patients with MSA.

Autonomic dysfunction in Parkinson disease and animal models

Parkinson disease has traditionally been classified as a movement disorder, despite patients' accounts of diverse symptoms stemming from impairments in numerous body systems. Today, Parkinson disease is increasingly recognized by clinicians and scientists as a complex neurodegenerative disorder featuring both motor and nonmotor manifestations concomitant with pathology throughout all major branches of the nervous system. Dysfunction of the autonomic nervous system, or dysautonomia, is a common feature of Parkinson disease. It produces signs and symptoms that severely affect patients' quality of life, such as blood pressure dysregulation, hyperhidrosis, and constipation. Treatment options for dysautonomia are limited to symptom alleviation because the cause of these symptoms and Parkinson disease overall are still unknown. Animal models provide a platform to interrogate mechanisms of Parkinson disease-related autonomic nervous system dysfunction and test novel treatment strategies. Several animal models of Parkinson disease are available, each with different effects on the autonomic nervous system. This review critically analyses key dysautonomia signs and symptoms and associated pathology in Parkinson disease patients and relevant findings in animal models. We focus on the cardiovascular system, adrenal medulla, skin/thermoregulation, bladder, pupils, and gastrointestinal tract, to assess the contribution of animal models to the understanding of Parkinson disease autonomic dysfunction.

Ocular features of multiple system atrophy

The aim of this paper is to gain better understanding of the ocular manifestations of multiple system atrophy (MSA), a neurodegenerative disorder rarely studied in terms of its ophthalmologic features. We performed a retrospective case series (1/1/05-12/31/14) to search for patients seen at Mayo Clinic, Rochester, MN, who had mention of MSA in the medical record and an eye examination, which yielded 285 cases. Of the 285, we identified 39 cases of true MSA. Each of these 39 patients was further reviewed for ocular abnormalities potentially related to MSA. Ocular findings potentially attributable to MSA were found in 64% of patients. Most common were dry eye (N = 14), conjugate eye movement abnormalities (N = 13), and ocular misalignment (N = 7). One patient had dry eye and monocular diplopia from trichiasis due to cicatricial pemphigoid, one had bilateral optic atrophy, and one had Adie's tonic pupil. Conjugate eye movement abnormalities (33%) and ocular misalignment (18%) were more common in patients with MSA-C. Patients with ocular findings, excluding dry eye, had a significantly shorter lifespan from time of initial neurologic symptoms to death. Our study confirms conjugate eye movement abnormalities and misalignment are common ocular findings in patients with MSA. Bilateral optic atrophy and cicatricial pemphigoid are possibly attributable to the disease. Ocular manifestations in MSA predict a poor prognosis as these patients have a significantly shorter lifespan. Therefore, we recommend patients with MSA have a comprehensive neuro-ophthalmologic exam at time of diagnosis, and thereafter, to screen for eye findings that may indicate a shorter lifespan.

Autonomic manifestations in acute sensory ataxic neuropathy: a case report

Acute sensory ataxic neuropathy (ASAN) is known to occur with acute and monophasic sensory ataxia. Although autonomic dysfunctions have been reported, no detailed descriptions are currently available. We describe a case of ASAN in which the autonomic manifestations were systematically investigated. Although the patient did not complain of any autonomic symptoms, except for photophobia due to mydriasis, autonomic testing revealed widespread autonomic dysfunctions. Norepinephrine and dobutamine infusion test indicated the presence of sympathetic dysfunction. Additionally, the pupillary response to pilocarpine revealed the presence of parasympathetic dysfunction. In conclusion, widespread, subclinical autonomic dysfunctions may be present in ASAN patients.

Pupillometry and 123I-DaTSCAN imaging in Parkinson's disease: a comparison study

The purpose of this study was the evaluation of pupil light reflex (PLR) in patients with Parkinson's disease (PD) by using a modern pupillometry system and the investigation of its potential relationship with dopamine transporter imaging (DaTSCAN), which is an objective method for the evaluation of presynaptic dopaminergic system. PLR was evaluated using pupillometry in 35 patients with PD without clinical evidence of autonomic dysfunction and 44 healthy matched controls. PLR was elicited using a fully automated pupillometry system and six parameters were measured. Dopamine transporter imaging was performed using radioactive ioflupane (123)I-FP-CIT [(123)I-N-ω-fluoropropyl-2β-carbomethoxy-3β-(4-iodophenyl)-nortropane]. A significant increase in latency and a significant decrease in amplitude, maximum constriction velocity, as well as maximum acceleration were observed in PD patients. There was no significant difference in initial radius and minimum radius values. Investigating the relationship between pupillometry parameters and (123)I-FP-CIT binding values, we correlated values from the semiquantitative analysis of radioligand uptake with pupillometry parameters, but we found no significant correlation. This study demonstrates PLR impairment in patients with PD without overt autonomic dysfunction. This impairment does not seem to correspond to the reduction of radioligand binding in the striatum as the result of presynaptic dopaminergic dysfunction, suggesting a different deterioration rate of these systems.

MIBG scintigraphy in differential diagnosis of Parkinsonism: a meta-analysis

OBJECTIVE

Differential diagnosis between Parkinson's disease (PD) and other Parkinsonism using clinical criteria or imaging methods is often difficult. The purpose of this study is to systematically review and meta-analyze published data about the diagnostic performance of myocardial innervation imaging using (123)I-metaiodobenzylguanidine (MIBG) scintigraphy in differential diagnosis between PD and other Parkinsonism.

METHODS

A comprehensive computer literature search of studies published through March 2011 regarding MIBG scintigraphy in patients with PD and other Parkinsonism was performed in PubMed/MEDLINE and Embase databases. Only studies in which MIBG scintigraphy was performed for differential diagnosis between PD and other Parkinsonism were selected. Pooled sensitivity, pooled specificity and area under the ROC curve were calculated to measure the accuracy of MIBG scintigraphy in differential diagnosis between PD and other Parkinsonism.

RESULTS

Nineteen studies comprising 1,972 patients (1,076 patients with PD, 117 patients with other Lewy body diseases and 779 patients with other diseases) were included in this meta-analysis. The pooled sensitivity of MIBG scintigraphy in detecting PD was 88% (95% CI 86-90%); the pooled specificity of MIBG scintigraphy in discriminating between PD and other Parkinsonism was 85% (95% CI 81-88%). The area under the ROC curve was 0.93.

CONCLUSIONS

In patients with clinically suspected PD, myocardial innervation imaging demonstrated high sensitivity and specificity. MIBG scintigraphy is an accurate test in this setting. Nevertheless, possible causes of false-negative and false-positive results should be kept in mind when interpreting the scintigraphic results.