Training in VNG

How to Differentiate Between Spinocerebellar Ataxia Subtypes Using VNG

10 mins
09 February 2022


This a great question. You have several different types of ataxia and some of these have specific findings on oculomotor testing. Spinocerebellar Ataxia type 3, for instance, you have square wave jerks and deficient gain in the video head impulse test. However, in SCA 3 you will rarely have spontaneous or positional nystagmus. On the other hand, with SCA 6, you do have positional downbeat almost in all patients. Lastly, SCA type 1, 2 and 17 are characterised by having slow saccades. Each of these disorders demonstrate specific findings on ocular motor testing making a VNG exam important in the differential diagnosis.


A photo of Dr. João Lemos
Dr. João Lemos
Dr. João Lemos, Neurologist and Neuro-Ophthalmologist, has worked in the field of oculomotor testing in neurological patients for 15 years, both as a clinician and researcher. He is based at Coimbra University Hospital Centre, Coimbra, Portugal. Dr. Lemos is the Director of the Neurology of Vision and Balance Unit in the hospital’s Neurology Department, which sees around 1500 neuro-ophthalmological and neuro-otological patients annually. 

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