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Abstract
Objective To characterize the clinical features in patients with spinocerebellar ataxia (SCA) type 1, SCA2, and SCA3 and to evaluate the oculomotor dysfunction by using optokinetic nystagmus (OKN) testing, which may be a sensitive marker.
Methods In this prospective observational study, all patients underwent detailed neurologic examination with special emphasis on eye movements. OKN was evaluated with a tape. Disease severity was measured with the International Co-Operative Ataxia Rating Scale (ICARS).
Results A total of 73 genetically confirmed patients were included, of whom 28, 30, and 15 patients were positive for SCA1, SCA2, and SCA3, respectively. Dystonia was more common in patients with SCA3 (46%), and absent ankle jerk was more common in those with SCA2 (21.4%). Brisk deep tendon reflexes were common in patients with SCA1 (46.6%), followed by patients with SCA3 (26.6%) and SCA2 (7.1%). Vertical OKN was impaired in all patients and absent in 86.6% of patients with SCA1, 96% of those with SCA2, and 80% of those with SCA3. Horizontal OKN was absent in 30% of patients with SCA1, 57% of patients with SCA2, and 33% of those with SCA3. Higher motor disability (posture and gait, kinetic functions [Motor Disability] subscore on the ICARS) was associated with higher oculomotor dysfunction measured by OKN-saccades impairment grading but not with the Ocular Disorder subscore of ICARS (ICARS-OD).
Conclusion OKN-saccades are a better and sensitive bedside clinical tool to quantify oculomotor dysfunction in neurodegenerative ataxias. Its role needs to be tested further in presymptomatic carriers. The current ICARS-OD scale to grade oculomotor dysfunction in degenerative ataxias need to be modified.
Glossarry
- EOM=
- extraocular movement;
- ICARS=
- International Co-Operative Ataxia Rating Scale;
- ICARS-MD=
- ICARS Motor Disability subscore;
- ICARS-OD=
- ICARS Oculomotor Disorders subscore;
- NI=
- neural integrator;
- OKN=
- optokinetic nystagmus;
- OKNs=
- OKN-saccades;
- RISCA=
- Prospective Study of Individuals at Risk for SCA1, SCA2, SCA3, SCA6, SCA7;
- SCA=
- spinocerebellar ataxias
Footnotes
Go to Neurology.org/N for full disclosures. Funding information and disclosures deemed relevant by the authors, if any, are provided at the end of the article.
- Received February 9, 2018.
- Accepted in final form June 28, 2018.
- © 2018 American Academy of Neurology
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