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International Cooperative Ataxia Rating Scale (ICARS)
Please visit this website for more information about the instrument: International Cooperative Ataxia Rating Scale Link.
Core: Friedreich’s Ataxia
Supplemental: Mitochondrial Disease.
Short Description of Instrument
The International Cooperative Ataxia Rating Scale (ICARS) is a commonly used evaluation and is composed of four clinical sub-scores involving the following:  
1)   posture and gait,  
2)   limb coordination,
3)   speech function
4)   oculomotor function.  
It was initially designed for longitudinal assessment of pharmacological therapies in patients with cerebellar ataxia.
Three criteria were chosen to work out the 100-point semi-quantitative scale.
1)   The tests needed to translate the classical symptomatology of ataxia into semi-quantitaive scores. Thus the simplest, most reproducible and most easily quantified tests were chosen.
2)   In each test, the scoring system needed to be precisely defined to reduce interobserver variations in the test performance.
3)   The 100-point scale was chosen so that the degree of ataxia could be expressed as a percentage of the maximum, indicating the severity of the ataxia.
The entire assessment is meant tot last less than 30 minutes.
The ICARS score is the total sum of the sub scores and ranges from 0 to 100, with 100 indicative of the most severely affected outcome.
Strengths: ICARS scores strongly correlate with the Ataxia Functional Composite Scale (AFCS), and with the Scale for the Assessment and Rating of Ataxia (SARA). ICARS is widely used and achieves a good interrater reliability. In addition to cerebellar ataxias, it has also successfully been applied in Friedreich ataxia, the prototype of an afferent ataxia.
Weaknesses: ICARS scores improve during normal development, until at least 13 years of age; thus, when used in pediatric studies, ICARS values could lead to misinterpretation of longitudinal outcomes, with “improved” scores being mistakenly representative of a therapeutic effect. ICARS scores may be difficult in < 4 years of age (dependent on child) and/or cognitive dysfunction. ICARS takes much more time to be administered than the SARA.
This scale was developed by an ad hoc Committee of the World Federation of Neurology who proposed a one-hundred point semi-quantitative International Cooperative Ataxia Rating Scale with compartmentalized quantification of postural or stance disorders, limb ataxia, dysarthria and oculomotor disorders, in order that a subscore relating to each of these symptoms could be separately studied. The weight of each symptomatologic compartment was carefully designed with precise definition of the tests, in order to minimize interobserver variations. The overall goal was to develop a cooperative ataxia rating scale that could be used in multicenter double-blind studies. A semi-quantitative 100-point scale was chosen. The entire assessment is meant to last less than 30 minutes.
Key Reference:  
Trouillas P, Takayanagi T, Hallett M, Currier RD, Subramony SH, Wessel K, Bryer A, Diener HC, Massaquoi S, Gomez CM, Coutinho P, Ben Hamida M, Campanella G, Filla A, Schut L, Timann D, Honnorat J, Nighoghossian N, Manyam B. International Cooperative Ataxia Rating Scale for pharmacological assessment of the cerebellar syndrome. The Ataxia Neuropharmacology Committee of the World Federation of Neurology. J Neurol Sci. 1997 Feb 12;145(2):205-11.
Other References:
Cano SJ, Hobart JC, Hart PE, Korlipara LV, Schapira AH, Cooper JM. International Cooperative Ataxia Rating Scale (ICARS): appropriate for studies of Friedreich’s ataxia? Mov Disord. 2005 Dec;20(12):1585-91.
Sival DA, Brunt ER. The International Cooperative Ataxia Rating Scale shows strong age-dependency in children. Dev Med Child Neurol. 2009 July; 51(7):571-2.
Storey E, Tuck K, Hester R, Hughes A, Churchyard A. Inter-rater reliability of the International Cooperative Ataxia Rating Scale (ICARS). Mov Disord. 2004 Feb;19(2):190-2.
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