A.6. Examinations in case of vertigo (n. VIII, central vs. peripheral vestibular lesions)

it is pure sensory nerve

examination of hearing

simplest method: ask a patient to cover his or her one of the ear and simpky rub your hand in front of the other ear. Normally, the patient should hear the noise.

Precise objective hearing: audiometry and BERA

WEBER

RINNE

Examination of vestibular system

Due to abnormal sensory innervation of CN VIII, the following symptoms can occur

1. nystagmus
2. vertigo
3. dizziness

nystagmus: involuntary rhythmic oscillation of the eye. it is caused by slow eye movement (slow component), which is followed by fast eye movement (fast component)

pathologic nystagmus: vestibular system (peripheral nystagmus), brainstem, cerebellar or retinal impairment, or drug induced

physiologic nystagmus: optokinetic nystagmus

The patient is looking at a moving object, e.g., a spinning, striped drum. The eye follows the movement, then quickly corrects. It can also be elicited by turning the patient round. The vestibuloocular reflex aims to keep the object on the fovea. Its presence is not examined routinely, but its examination may be helpful in the case of psychogenic “blindness”

Based on appearance:

1. spontaneous nystagmus: it is observed when patient is looking forward at rest
2. provoked nystagmus: we need some provoking factor (gaze) to see nystagmus. Gaze evoked nystagmus is seen when patient is gazing at one point.

Direction of nystagmus: can be horizontal vertical, rotational or combination of them. The direction of the nystagmus is named after quick movement.

1. Pendular nystagmus: If the two-directional movements are of equal velocity. It is usually central (mainly cerebellar).
2. The direction changing nystagmus: or bidirectional nystagmus changes its direction while looking at the other direction. E.g., if the patient looks right, the direction of nystagmus is right, if the patient looks left, the direction of nystagmus is left. It is usually of central origin.
3. the combined nystagmus is seen in narcotics, drugs, alcohol or posterior fossa space occupying lesions.

Degree of nystagmus:

• 1st degree nystagmus: is present only when looking at the direction of the quick component.
• 2nd degree nystagmus: is present when looking at the direction of the quick component and when looking straight ahead.
• 3rd degree nystagmus: is present when looking at the direction of the quick component and when looking straight ahead

How do you differentiate central or peripheral nystagmus?

Peripheral nystagmus can be inhibited by visual fixation. Usually up and down nystagmus is caused by cerebral stroke

1. Frenzel's glasses are the best for inhibition of fixation because the glasses inhibit the patient's fixation and examiner can see patient's eye magnified
2. Pupil lamp: ask the patient to cover one of his eyes. Illuminate the other eye with the lamp. The point of light reflected on the cornea helps to observe the nystagmus.

Examination of balance (vertigo)

• Romberg test

Ask patient stand with their feet together, hands to the sides and eyes are closed/ Watch out for excessive swing

People with cerebellar ataxia sway regardless of eye closed or open

• Sharpened Romberg test

Ask patient to place one of his or her feet in front of the other one while eyes are closed (heel to toe position). In pathological cases, patients sways to the same side regardless of which foot is in front, in other hand the patient sways to the opposite sides depending on which foot is in front in case of psychogenic cases.

• Blind walking test

Ask patient to walk straight and eyes are closed about 5 meter.

• Unterberg test = Fukuda test

By eliminating any external stimuli (ex: noise), ask patient to walk in place for 30s. if patient starts to rotate, test is positive.

• tandem gait test (heel to toe test)

ask patient to walk in heel to toe in straight line.

• Caloric testing (prior examination make sure patient's eardrum is intact)

pour 20–50 ml cold water into the outer ear canal. Normally eyes deviate to the site of stimulus and turn to the other direction with quich nystagmus jerk.