Skew deviation can help localize central vestibular pathology because it indicates which of the following?

• A. Inner ear labyrinthine damage
• B. Visual acuity impairment
• C. Peripheral vestibular weakness
• D. Brainstem/cerebellar involvement affecting otolith-ocular pathways

Answer: (D)

Skew deviation signals central involvement because it arises when brainstem or cerebellar circuits that integrate otolith inputs with eye movements are disrupted. The otolith-ocular pathways carry signals from the vestibular organs to the ocular motor system through the brainstem and cerebellum; a lesion in these central structures can create an asymmetric signal to the ocular muscles, producing a vertical misalignment of the eyes (skew) often accompanied by an ocular tilt reaction. This pattern points to central vestibular pathology rather than a peripheral labyrinth problem.

In contrast, inner ear (peripheral) damage typically causes vertigo with nystagmus and abnormal caloric or head-impulse tests, not a primary vertical eye misalignment. Visual acuity impairment is not a vestibular localization sign, and peripheral weakness refers to unilateral vestibular function loss with different clinical signs. So the presence of skew deviation most strongly localizes to brainstem or cerebellar involvement affecting otolith-ocular pathways.