Spinocerebellar degeneration with negative electroretinogram: dysfunction of the bipolar cells

Abstract

We report the characteristics of three patients with spinocerebellar degeneration (SCD) with negative-type electroretinograms (ERGs). None of the patients showed retinal degeneration, but all had severe cerebellar ataxia, and brain MRIs showed cerebellar atrophy. Negative-type ERGs have been implicated in the selective functional impairment of the inner retinal layer, but few studies have reported dysfunction of the inner nuclear layer in SCD patients. Our subjects may be the first reported SCD cases with negative-type ERGs. Our results suggest that an etiologic relationship exists between cerebellar ataxia and negative-type ERGs. Further investigation of ERGs in patients with SCD could potentially lead to the identification of an increased number of SCD patients with negative-type ERGs and retinal pathogenesis.

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

“…In the past few years there have been three reports of patients with cerebellar degeneration displaying a negative ERG [9][10][11]. The term cerebellar degeneration refers to a heterogeneous group of diseases in which ataxia, or a loss of muscle coordination, is the primary symptom.…”

“…The seven ataxic patients described in the reports by Kimura et al, Hagan et al, and Saito et al [9][10][11] had a negative ERG in common, but they differed in other characteristics such as the severity of their cognitive loss. The patients also differed in their ERG responses to other stimuli (e.g.…”

“…The patients also differed in their ERG responses to other stimuli (e.g. nearly normal responses for two patients in [9], but non-detectable dim flash responses and reduced photopic responses for the three patients in [10]). Five of the patients had a positive family history for ataxia, including three family members in Hagan et al [10], and two unrelated patients [9,11].…”

“…nearly normal responses for two patients in [9], but non-detectable dim flash responses and reduced photopic responses for the three patients in [10]). Five of the patients had a positive family history for ataxia, including three family members in Hagan et al [10], and two unrelated patients [9,11]. Those two patients were found to have mutations in the SCA-1 gene, but the other five patients in these reports were tested for the known SCA mutations and found to be negative.…”

“…Based on the earlier reports [9,11], he was screened for SCA mutations, but none was found. Furthermore, his symptoms were quite different from those of the SCA patients reported to-date, leading to a diagnosis of probable MSA, and demonstrating greater breadth in the cases of negative ERGs associated with ataxia.…”