A cerebellar exam may include saying phrases with many consonants to detect scanning speech, detecting horizontal gaze nystagmus by following a finger with the eyes, performing rapid alternating movements like rotating a hand from palm to back repeatedly, testing the Holmes rebound phenomenon, and testing patellar reflex for hypotonia or hypertonia. Common scales include the International Cooperative Ataxia Rating Scale (ICARS) and Scale for the Assessment and Rating of Ataxic Disorders (SARA) for evaluating the severity of ataxia as a symptom. ICARS measures on a 100 scale, where 0 is normal function and 100 is the highest possible impairment, assigning different point values for different tests. The tests are divided into categories evaluating posture and gait, kinetic functions, speech, and oculomotor functions. While these categories create useful categorization to assess which areas need to be focused on in therapies, this redundancy results in a longer test time, which can skew results of tests performed at the end of a session; and can result in contradictory scores. SARA is a shorter exam, evaluated on a scale of 0 to 40, where again zero is normal function and 40 is highest possible impairment. It comprises eight tests: gait, stance, finger chase, finger-to-nose test, fast alternating hand movements, heel-shin slide, and three limb kinectic function tests. Differential diagnosis
Differential diagnosis of SCAs by clinical methods is difficult because these diseases are clinically heterogenous and there is significant variance between the expression of individual cases.
History
Ataxia as a symptom was first described by French neurologist Duchenne de Boulogne in a subject with tabes dorsalis. By the late 19th and early 20th centuries, extensive research into the characterization, cause, and diagnostics of hereditary cerebellar ataxias was underway with the work of several prominent neurologists, including Jean-Martin Charcot, Pierre Marie, Nikolaus Friedreich, Adolph Strümpell, and others. Marie described a number of cases of hereditary, adult onset disease he thought to be clinically distinct from Friedreichs ataxia, spastic paraplegia, and other known types of ataxia, calling the syndrome hereditary cerebellar ataxia, though it became known Maries ataxia.While the hereditary patterns were clearly distinct, there was on-going debate well into the 1940s over whether Maries ataxia was really distinct from Freidreichs ataxia and Strümpells paraplegia and if these categorys themselves represented a single disease or many. This was because of the heterogenous nature of hereditary ataxias, the similarity of symptoms, and the lack of understood biochemical mechanisms. Further frustration with the ambiguity of terms introduced by Marie and Friedreich resulted in the creation of other systems to classify ataxias. Gordon Morgan Holmes and Godwin Greenfield each developed systems of categorizing ataxias, giving rise to categories called olivopontocerebellar atrophy and spinocerebellar degradation, though little consensus between the systems was achieved, and many terms are used interchangeably.In the depression era United States, the Schut family in Minnesota was one family known to carry a hereditary ataxia.