International Cooperative Ataxia Rating Scale for pharmacological assessment of the cerebellar syndrome

Abstract

Despite the involvement of cerebellar ataxia in a large variety of conditions and its frequent association with other neurological symptoms, the quantification of the specific core of the cerebellar syndrome is possible and useful in Neurology. Recent studies have shown that cerebellar ataxia might be sensitive to various types of pharmacological agents, but the scales used for assessment were all different. With the long-term goal of double-blind controlled trials —multicentric and international — an ad hoc Committee of the World Federation of Neurology has worked to propose a one-hundred-point semi-quantitative International Cooperative Ataxia Rating Scale (ICARS). The scale proposed involves a compartimentalized quantification of postural and stance disorders, limb ataxia, dysarthria and oculomotor disorders, in order that a subscore concerning these symptoms may be separately studied. The weight of each symptomatologic compartment has been carefully designed. The members of the Committee agreed upon precise definitions of the tests, to minimize interobserver variations. The validation of this scale is in progress. © 1997 Elsevier Science B.V. All rights reserved.

Introduction

Cerebellar disturbances are observed in an extremely large range of conditions and are frequently associated with other neurological symptoms. However, a core of specific symptoms has been defined in classical reports from Babinski (Babinski, 1899; Babinski, 1906; Babinski, 1913; Babinski and Tournay, 1913) and Holmes (Holmes, 1917; Holmes, 1922a; Holmes, 1922b; Holmes, 1922c; Holmes, 1922d), and named cerebellar syndrome. The term ataxia, originally coined for the description of dysequilibrium manifestations due to the sensitive defects of tabes, was progressively applied to cerebellar symptoms, not only to postural disturbances, but also to limb coordination disturbances (Holmes, 1917; Holmes, 1922b). In the terms ‘heredoataxias’ or ‘spino-cerebellar ataxias’, the concept of ataxia has been used loosely as an equivalent of cerebellar syndrome. In a more restrictive but widely accepted conception, the cerebellar syndrome basically involves cerebellar ataxia, hypotonia and intention tremor, just as the extrapyramidal syndrome involves akinesia, hypertonia and rest tremor.

In the classical descriptions, it was suggested that the intensity of each symptom and the addition of the different symptoms might indicate the global severity of the syndrome and the intensity of chronic cerebellar lesions (Babinski, 1913; Babinski and Tournay, 1913). These early remarks give a legitimacy to the present attempt at quantification of the cerebellar syndrome.