Macular Dysfunction and Morphology in Spinocerebellar Ataxia Type 7 (SCA 7)

Abstract

The patients with genetically confirmed SCA 7 presented an early macular dysfunction, preceding any signs of abnormalities in fundus appearance. According to the electrophysiological findings the primary dysfunction involves the cone photoreceptors in the foveal region, however in an older patient involvement of cone photoreceptors throughout the retina was verified. This is in accordance with the theory that ataxin-7 interacts with CRX transcription, since it is known that mutations in the CRX gene cause cone-rod dystrophy.

Two Patients With Spinocerebellar Ataxia Type 7 Presenting With Profound Binocular Visual Loss Yet Minimal Ophthalmoscopic Findings

“…In our first patient, who had more severe visual loss, there was very subtle pigmentary mottling in the macular regions and possibly mild temporal optic disc pallor. Review of fundus photographs from previously reported SCA-7 patients, in which the ocular fundi were considered normal, suggests that subtle abnormalities, such as retinal arterial attenuation, may have been present but overlooked 12. A prospective study of individuals with the SCA-7 mutation is required to further delineate the sequence of ocular fundus changes in relation to symptom onset and visual function parameters.…”

Ataxia Severity Correlates with White Matter Degeneration in Spinocerebellar Ataxia Type 7

“…3,4 Furthermore, patients may eventually develop other neurologic deficits, including loss of manual dexterity, speech dysarthria, dysphagia, and eye movement abnormalities. 2 A number of neuropathologic studies have documented the anatomic consequences of the neurodegenerative process. These include severe degeneration of the cerebellar cortex and other cortical regions.…”

“…1 SCA7 is considered one of the rarest forms of genetic autosomal dominant cerebellar ataxia. 2 Clinically, SCA7 is characterized by a combination of cerebellar ataxia and macular degeneration and is the only spinocerebellar ataxia that manifests in permanent blindness. 3,4 Furthermore, patients may eventually develop other neurologic deficits, including loss of manual dexterity, speech dysarthria, dysphagia, and eye movement abnormalities.…”

Multimodal Imaging of a Family With Spinocerebellar Ataxia Type 7 Demonstrating Phenotypic Variation and Progression of Retinal Degeneration

“…In this instance, OCT imaging was essential to diagnosis. Earlier papers have reported retinal thinning on OCT in patients with SCA7 5,6 . The OCT for Patient 3 demonstrates outer retinal atrophy with loss of the outer nuclear layer and ellipsoid zone in the central macula.…”