Snapshot: What is the International Cooperative Ataxia Rating Scale?

The International Cooperative Ataxia Rating Scale (ICARS) is an assessment of the degree of impairment in patients with cerebellar ataxia. It was developed in 1997 by the Committee of the World Federation of Neurology. The goal of ICARS is to provide a standardized clinical rating score to measure the efficacy of potential treatments. The scale was intended for patients with cerebellar ataxia. But ICARS has also been validated for patients with focal cerebellar lesions, spinocerebellar, and Friedrich’s ataxia.

How Does it Work?

The ICARS is a semi-quantitative examination that translates the symptomatology of cerebellar ataxia into a scoring system out of 100. The assessment is designed to be completed within 30 minutes, and higher scores indicate a higher level of disease impairment. The assessment consists of 19 items and four subscales of postural and gait disturbances, limb movement disturbances, speech disorders, and oculomotor disorders. Detailed descriptions of the scoring metrics are also provided to reduce scoring variability between the examiners.

Advantages and Drawbacks

Since its development, multiple studies have validated the ICARS. It has also been widely used in clinical assessment for ataxia rating of different diseases. One such study accessed 14 instruments of ataxia assessment and identified the ICARS to be highly reproducible and internally consistent.

However, the scale also does not account for some ataxia symptoms, such as hypotonia (muscle weakness), that are difficult to access clinically. Some subscales also have a considerable ceiling effect, where many patients reach the maximum score for a category. This means symptoms are not being accessed past a certain severity.

Doctor writing down patient notes on a clipboard using a checklist while sitting at a desk.
The ICARS is a semi-quantitative examination that translates the symptomatology of cerebellar ataxia into a scoring system out of 100. Photo used under license by eggeegg/Shutterstock.com.

Other Ataxia Rating Scales

The Scale for the Assessment and Rating of Ataxia (SARA) is another semi-quantitative assessment of impairment levels. It consists of only eight items, making it easier to perform for frequent assessments. However, the simplification of the scale excludes some important symptomatology, including oculomotor impairment.

A pilot study has also been conducted for the development of SARAhome, a video-based variation of SARA that can be conducted independently at home, showing promise for the digitization of ataxia assessment.

Another assessment scale that is even more toned-down is the Brief Ataxia Rating Scale (BARS). The scale consists of five items that assess gait, speech, eye movement, and limb mobility, and the estimated assessment time is only five minutes.

All the assessments described above have been validated and each has its own benefits and drawbacks. However, none of them provides the minimal important difference, which is an important clinical measurement used to determine the effectiveness of potential treatment. Therefore, we are still in need of developing better tools for measuring disease impairment in ataxia patients.

If you would like to learn more about ICARS, take a look at this resource by Physiopedia.

Snapshot written by Christina (Yi) Peng and edited by Dr. Hayley McLoughlin.

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