absence of other cranial nerve pathology except impaired corneal reflex (acoustic neuroma)
central vertigo features
nystagmus characteristics
vertical or torsional nystagmus
if horizontal then direction of fast phase alternates with gaze direction
unilateral or bilateral
may be enhanced by visual fixation
nystagmus induced by head position testing:
short latency
sustained duration
non-fatigable
other suggestive features
wide based ataxic gait or truncal ataxia whilst sitting with arms on lap
homonymous hemianopia or quadrantanopia - suggests occipital visual cortex stroke which may also be associated with a cerebellar stroke causing ataxia, vertigo