Measuring Neurological Impairment and Functional Visual Assessment In Spinocerebellar Ataxias

Overview

Measuring the various difficulties patients with spinocerebellar ataxias (SCA) report in an accurate manner is important to be able to test any therapy that may be developed. As basic research identifies some therapy of this type, clinicians are planning studies that can either prove or disprove that such treatments actually have an effect. Walking problems and problems with eye movements that can give rise to visual complaints are common in the SCA's. Existing neurological scales such as the "SARA" are based on the usual neurological examination items that can carry a degree of subjective bias. Also the intervals between numbers on such scores often do not carry the same "weight" so that the difference between a score of 1 and 2 may not be equal to difference between 2 and 3. Lastly, such scales done in the clinic setting capture only a brief period of a patient's day. We propose that examination of home based gait monitoring, timed tests of motor function and quantitative measures of visual problems in patients with SCA are more useful in measuring the disability in these patients.

Spinocerebellar ataxias (SCA's) are relatively rare, inherited disorders of the cerebellum that cause inexorably progressive imbalance and incoordination as well as speech problems. Recent molecular genetic studies have raised hopes for meaningful treatments for these conditions. Before one can embark on therapeutic studies on the SCA's it is essential that we have validated instruments for measuring disease progression. Rating scales based on neurological examinations have been reported recently but their sensitivity to change and reproducibility are still being examined. In an attempt to produce readily quantifiable and sensitive measures of motor function in the SCA's, we are proposing to examine the utility of home based gait monitoring, timed tests of motor function and quantitative measures of visual problems in patients with SCA's. These measurements which will produce continuous rather than categorical variables, and may be subject to less arbitrariness on the part of the examiner, are hypothesized to be not only valid measures but also more sensitive. The overall aim of the project is to assess the utility of home based gait monitoring, timed performance measures and functional visual testing as measures to monitor disease progression in SCA's. The concurrent validity of these measures will be tested by correlating them with an established examination based ataxia scale (Scale for assessment and rating of ataxia: SARA), an activity of daily living scale (Barthel index) and functional staging. Aim 1: Hypothesis: Motor impairment in SCA's can be assessed validly in the home setting by utilizing the step activity monitor (SAM). Aim 2: Hypothesis: Motor impairment in SCA's can be further quantified using performance measures: the 9-hole peg board test and the timed 25 foot walk. Aim 3: Hypothesis: Visual problems reported by patients with SCA's can be quantified by low contrast vision testing, stereoacuity measures, color vision and vergence amplitudes utilizing well-established ophthalmologic techniques. Aim 4: Hypothesis: The neurological impairment as measured by these measures will correlate with each other, with scores on SARA, with the Barthel index score and with functional staging. Aim 5: Hypothesis: Ataxia grading using the SAM, timed performance measures and functional visual scores will be more sensitive than SARA for measuring disease progression