In my experience, differentiating between central and peripheral dysfunction starts with their subjective explanation of their symptoms. I listen and probe for key words to help me determine my differential diagnoses (vertigo, imbalance, light-headed, swimming) along with when they experience their symptoms – such as always with head movement or not. I, then, complete a thorough oculomotor exam including individual tests for the CNS and peripheral vestibular system. Collectively, this will help identify any “red flags” implying any undetected CNS involvement such as a tumor. If this is suspected, I would continue my evaluation with cranial nerve testing, reflex testing, etc. Oculomotor testing that is normal with the exception of VOR or head-thrust test would imply vestibular hypofunction and I would further evaluate balance and coordination. A normal oculomotor exam with no apparent peripheral dysfunction would direct me to the possibility of migraines, motion sensitivity, or something of that nature.
Oculomotor Exam
smooth pursuit (central function)
– spontaneous nystagmus (peripheral)
– gaze evoked nystagmus (central)
saccades (central)
convergence/divergence (central)
VOR (peripheral)
VOR cancellation
head-thrust (peripheral)
optokinetic stimulation (central)
Hope that helps!