Vestibular Function Tests

Semicircular Canals Tests

1. Semicircular canal test includes electro-nystagmography (ENG)
2. ENG is a battery of tests that measure oculomotor, inner ear function, and nystagmus in different head positions.
3. ENG test includes:
1. Caloric Test
1. Infusion of cold and warm water into the external auditory canal with the help of a syringe so that it touches the tympanic membrane.
2. This stimulus introduces a temperature gradient which results in the convective flow of endolymph that deflects the cupula and generates nystagmus from the horizontal semicircular canal.
2. Rotational Chair Test
1. This test stimulates each semicircular canal by rotating the patient in the dark.
2. In patients with normal vestibular function, nystagmus should be generated by rotation.
3. In the presence of vestibular disorder, the pathology can be determined by comparing VOR gain and phase from rotation toward one ear with rotations towards the opposite ear.
4. The rotational chair test is the standard test for bilateral vestibular hypofunction.

Otolith Tests

1. Vestibular-Evoked Myogenic potential (VEMP) Test
1. VEMP uses the threshold and amplitude of a muscle contraction (EMG) to classify pathology.
2. VEMP includes:
1. Cervical VEMP
2. Ocular VEMP