If caloric testing shows unilateral weakness with normal saccades and smooth pursuit, what is the most likely interpretation?

If caloric testing shows unilateral weakness with normal saccades and smooth pursuit, what is the most likely interpretation?

• A. Central vestibular pathology
• B. Peripheral vestibular pathology
• C. Normal vestibular function
• D. Central and peripheral combined pathology

Answer: (B)

Caloric testing assesses the function of the horizontal semicircular canal and the vestibular nerve at low frequencies. A unilateral weakness means one ear isn’t driving the vestibulo-ocular reflex as strongly, indicating a peripheral vestibular deficit on that side. Normal saccades and smooth pursuit show the central ocular motor pathways are intact, so the central nervous system isn’t the source of the problem. Therefore, the most likely interpretation is a peripheral vestibular pathology on the side with the reduced caloric response.

Caloric testing assesses the function of the horizontal semicircular canal and the vestibular nerve at low frequencies. A unilateral weakness means one ear isn’t driving the vestibulo-ocular reflex as strongly, indicating a peripheral vestibular deficit on that side. Normal saccades and smooth pursuit show the central ocular motor pathways are intact, so the central nervous system isn’t the source of the problem. Therefore, the most likely interpretation is a peripheral vestibular pathology on the side with the reduced caloric response.