Chromatic pattern-reversal electroretinograms (ChPERGs) are spared in multiple system atrophy compared with Parkinson’s disease

Abstract

Idiopathic Parkinson's disease (IPD) patients have abnormal visual evoked potentials (VEPs) and pattern electroretinograms (PERGs), attributed to dopaminergic transmission deficiency in visual pathway, probably the retina. VEP abnormalities are not reported in multiple system atrophy (MSA). The aim of this study was to investigate and compare chromatic (Ch) red-green (R-G) and blueyellow (B-Y), and luminance yellow-black (Y-Bk) PERGs in patients with MSA and IPD. We investigated 6 MSA patients (mean age: 62±7.4 years) not undergoing any pharmacological treatment, as well as 12 early IPD patients (mean age: 60.1±8.3 years) and 12 age-matched normal observers. ChPERGs were recorded monocularly in response to full-field equiluminant R-G, B-Y and Y-Bk horizontal gratings. In MSA only responses to R-G stimuli showed minimal insignificant changes (slight but not significant amplitude reduction without any significant latency delay); no significant abnormality was detected for B-Y and luminance Y-Bk stimuli. By contrast, in IPD all responses were reduced in amplitude and delayed in latency, above all for B-Y stimuli. Present data indicate that both chromatic and achromatic PERGs are virtually unaffected in MSA, whereas in early IPD they are clearly impaired, suggesting different pathogenic retinal mechanisms and a useful simple tool for distinguishing MSA from IPD.

The mouse pattern electroretinogram

“…Patterns made of chromatic-contrast stimuli are also used to isolate color-opponent RGC subpopulations and identify their vulnerability in disease [10][11][12][13][14][15][16].…”

Clinical Significance and Pathogenesis of Visual Impairment in Parkinson’s Disease

“…Examinations by chromatic pattern ERG with red-green and blue-yellow grids, as well as black-white grids used during achromatic pattern ERG provides a discriminating approach to revealing disorders in parvo, konio and magnocellular pathways. Previous studies have shown an inhibition of pattern ERG amplitude, both to chromatic and achromatic stimuli, in PD, moreover, when exposed to blueyellow grid stimuli, an increased latency of the principal peaks was revealed beside an essential reduction of the amplitude [24]. The different degrees of parvo-, konio-and magnocellular subsystems involvement in PD is further confirmed by visual evoked potentials (VEP) with achromatic and chromatic reverse checkered patterns of blue-yellow and red-green checks.…”

A negative electroretinogram (ERG) in a case of probable multiple system atrophy (MSA)

“…However, visual function and electrophysiological responses have not been studied much in MSA, and few abnormalities have been noted. For example, there were no differences in performance between six MSA patients and the agematched controls tested on sinewave-grating contrast detection and discrimination tasks [21,38] [24], and that 'visual disturbances are not part of the clinical spectrum of MSA' ( [22], p. 113). Although the present patient has no significant visual complaints, the present ERG results suggest that there may be unrecognized retinal dysfunction in some patients with MSA.…”

“…The more common subtype, referred to as MSA-P, shows prominent parkinsonian features such as rigidity and postural tremor, whereas MSA-C includes more motor features of cerebellar ataxia, such as dysarthria, gait ataxia and oculomotor abnormalities [19]. There are reports in the literature of oculomotor abnormalities in MSA such as square wave jerks and nystagmus [18,20], but visual system problems generally are not considered to occur in MSA (e.g., [21][22][23]), leading to the suggestion that the visual system is 'believed to be spared' in MSA ( [24], p. 395).…”