Ataxia, nystagmus, vertigo (295/1700)

A 34yo male presents with hx of headache presents with ataxia, nystagmus and vertigo. Where
is the site of the lesion?
a. Auditory canal
b. 8th CN
c. Cerebellum
d. Cerebral hemisphere
e. Brain stem






























answer: C
cerebellar ataxia, inv of choice MRI


The cerebellum can be divided into central structures (lingula, vermis and flocculonodular lobe) and the cerebellar hemispheres. Main inputs come from frontopontocerebellar connections (contralateral) from above, and spinocerebellar tracts from below (proprioception) producing primarily ipsilateral signs. Midline lesions can produce severe gait and truncal ataxia. As they extend they can also give fourth cranial nerve lesions and severe ipsilateral arm tremor, marked nystagmus, vertigo and vomiting, and can block CSF flow (obstructive hydrocephalus).
Cerebellar hemisphere lesions can produce classic ipsilateral limb ataxia (intention tremor, past pointing and mild hypotonia). Limb rebound can be demonstrated by gently pushing down on outstretched arms and then suddenly releasing, causing the arm on the affected side suddenly to fly upwards. Lateral lesions tend to produce more subtle nystagmus (maximal looking towards side of lesion).