Vestibular Examination Flashcards
Vestibular hypofunction can be due to…
Otolith involvement or semicircular canal involvement
Otolith involvement
Impaired orientation to static head position and linear acceleration/deceleration
What are the symptoms associated with otolith involvement?
Motion sickness, visual impairments, imbalance, nausea/vomiting
Semicircular canal involvement
impaired VOR
What signs and symptoms are associated with semicircular involvement?
Nystagmus, imbalance, nausea/vomiting
Nystagmus
repetitive, to-and-fro movement of the eyes characterized by a fast and slow phase.
What are the different pathological and non-pathological eye movements that can be observed during a vestibular examination?
- Smooth pursuit
- Saccades
- VOR
- Optokinetic
- Nystagmus
What is the primary diagnostic indicator used in identifying most peripheral and central vestibular lesions?
Nystagmus
What is the primary symptom associated with the presence of nystagmus?
VERTIGO
What are the three types of nystagmus and how, in general, do they differ?
- Spontaneous: occurs at rest
- Evoked nystagmus: occurs with trigger
- Non-pathological nystagmus: end-range eye movements
An audiogram assesses
for auditory asymmetry, significant difference in threshold hearing levels between ears (retrocochlear pathology or ear canal + tympanic membrane integrity)
Retrocochlear pathology
unilateral sensorinueral loss, impaired speech recognition d/t damage of cranial nerve VIII or CNS structures
Ear canal and Tympanic Membrane Integrity Pathology
Conductive Hearing Loss (variety of causes)
Electronystagmography (ENG)
electrodes are placed around the eye to measure VOR via muscular activation
Videonystagmography (VNG)
Utilizes video goggles to monitor eye movements and VOR
More common than ENG
What is the gold standard to assess for unilateral peripheral vestibular hypofunction?
Caloric Testing
Caloric Testing
evaluates integirty of unilateral vestibular apparatus (horizontal canal comparative exam)
Explain how caloric testing works
Cold irrigations generate nystagmus in the Opposite direction,
Warm irrigations generate nystagmus in the Same direction
Normally
What is indicative of a (+) caloric test for peripheral vestibular hypofunction?
Significant asymmetry in nystagmus amplitude (>25% difference in peak slow components eye movement)
Cold in involved ear - HUGE nystagmus towards contralateral ear; warm in involved ear, decreased response of nystagmus OR switches to ipsilateral ear
Vestibular Evoked Myogenic Potential (VEMP)
Measures otolith function via muscle reflex in neck or eye with electrodes.
cVEMP
measures saccule function via VST
Measurement of reflexvie SCM ipsilaterally in reponse to sound
oVEMP
measures utricle function via MLF
Measurement of reflexive inferior oblique contralaterally to air or bone conducted sound.
Abnormal VEMP Results
- No muscular response to sound
- Asymmetrical response R vs L
What is the gold standard for diagnosis of bilateral vestibular hypofunction (BVH)?
Rotational Chair Test
