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. Using clinical information for differential diagnosis is used to prioritize genetic testing not as a stand-alone diagnosis. Many potential differentiating symptoms have been found, and methods of assessing many symptoms and their progression to guide genetic testing have been developed. Even if a specific type of spinocerebellar ataxia cannot be immediately determined clinical history, family history, clinical examination can help distinguish between other ataxias and can help reduce the number of genetic tests needed to identify a type of SCA. Examination of relatives of individuals thought to have sporadic ataxia can often reveal enough family history to identify a transmission mode. There are some common trends that may be useful to discriminate SCAs. SCA1 tends to progress faster than SCA2, 3, and 6, with greater annual change in SARA scores and earlier loss of functions after onset. In the diagnostics of clinical ataxia, imaging may not be useful to distinguish SCA1 from other SCAs as there is significant variance between individual cases and significant overlap between diseases. Vestibulo-ocular reflex can be tested using a video recorded head impulse test or vHIT. In this test, SCA1 typically has normal reflex latency, and does not consistently show a deficit in VOR function, distinguishing it from SCA3 and Friedreich's ataxia. Certain patterns in ocular motor disorders, detectable with video-oculography, appear to typify certain SCA types.