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Mackenzie Vestibular practice questions

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Question 1Vestibular Anatomy and Physiology

Which cranial nerve carries primary afferent signals from the posterior semicircular canal to the brainstem?

  1. Vestibulocochlear nerve (CN VIII) Correct answer.
  2. Glossopharyngeal nerve (CN IX)
  3. Facial nerve (CN VII)
  4. Trigeminal nerve (CN V)

Explanation

Vestibular hair cells synapse onto primary afferents that travel in the vestibular division of the eighth cranial nerve, which enters the brainstem at the pontomedullary junction. The other cranial nerves listed serve facial movement, facial sensation and taste respectively, and carry no canal afferents.

Question 2Vestibular Anatomy and Physiology

The sensory hair cells of the vestibular end organs are located within which structure?

  1. The spiral ligament of the cochlea
  2. The endolymphatic sac wall
  3. The neuroepithelium of the maculae and cristae Correct answer.
  4. The tectorial membrane

Explanation

Vestibular transduction occurs in a neuroepithelium containing type I and type II hair cells. This epithelium forms the maculae of the utricle and saccule and the cristae ampullares of the semicircular canals.

Question 3Vestibular Anatomy and Physiology

Which structure contains the otolithic membrane with embedded calcium carbonate crystals?

  1. The organ of Corti
  2. The ampullary cupula
  3. The crista ampullaris
  4. The macula of the utricle Correct answer.

Explanation

Otoconia, small calcium carbonate crystals, sit in a gelatinous layer over the maculae of the utricle and saccule. Their mass makes the membrane sensitive to gravity and linear acceleration.

Question 4Vestibular Anatomy and Physiology

Which end organ primarily detects angular acceleration of the head?

  1. The utricle
  2. The cochlea
  3. The saccule
  4. The semicircular canals Correct answer.

Explanation

Each semicircular canal is a fluid-filled torus interrupted by the ampulla, and rotation of the head in the plane of a canal drives endolymph flow that deflects the cupula. The canals are therefore angular accelerometers, while the otolith organs sense linear forces.

Question 5Vestibular Anatomy and Physiology

At rest, the discharge rate of a typical vestibular afferent is best described as which of the following?

  1. Zero until movement begins
  2. A steady spontaneous rate that can rise or fall Correct answer.
  3. A rate that only decreases with stimulation
  4. A rate that is maximal at rest and cannot increase

Explanation

Vestibular afferents fire continuously at rest, and this resting discharge is the baseline against which both excitation and inhibition are encoded. Head motion can therefore increase or decrease firing from the same baseline.

Question 6Vestibular Anatomy and Physiology

Deflection of the stereocilia toward the kinocilium produces which immediate effect in a vestibular hair cell?

  1. Opening of mechanically gated channels and depolarization Correct answer.
  2. Increased potassium conductance through voltage-gated calcium channels
  3. Closure of mechanically gated channels and hyperpolarization
  4. Release of glutamate onto hair cells

Explanation

Tip links couple adjacent stereocilia, so bending toward the tallest cilium opens mechanically gated transduction channels. Potassium influx then depolarizes the hair cell and increases transmitter release.

Question 7Vestibular Anatomy and Physiology

The kinocilium of a vestibular hair cell is positioned where relative to the stereocilia?

  1. Beneath the cuticular plate
  2. At one edge of the bundle as the tallest cilium Correct answer.
  3. At the center of the hair bundle
  4. Within the supporting cell layer

Explanation

Each hair bundle shows a staircase arrangement with the kinocilium located at one pole as the tallest element. This structural polarity defines the axis along which deflection produces excitation or inhibition.

Question 8Vestibular Anatomy and Physiology

The membranous labyrinth is filled with which fluid?

  1. Blood plasma
  2. Cerebrospinal fluid
  3. Endolymph Correct answer.
  4. Perilymph

Explanation

Endolymph fills the closed membranous labyrinth and is unusual among extracellular fluids for its high potassium and low sodium content. Perilymph occupies the space between the membranous and bony labyrinths.

Question 9Vestibular Anatomy and Physiology

The utricle and saccule are linked by which membranous duct?

  1. The utriculosaccular duct Correct answer.
  2. The semicircular duct
  3. The cochlear duct
  4. The endolymphatic duct

Explanation

A short utriculosaccular duct joins the utricle and saccule and continues as the endolymphatic duct. This connection is part of the continuous endolymphatic space of the inner ear.

Question 10Vestibular Anatomy and Physiology

An excitatory deflection of a horizontal canal hair cell occurs when stereocilia bend in which direction?

  1. Away from the kinocilium
  2. Toward the kinocilium Correct answer.
  3. Toward the utricle
  4. Parallel to the crista surface

Explanation

Excitation follows deflection toward the kinocilium, which opens transduction channels and depolarizes the cell. In horizontal canal cristae the kinocilia face the utricle, so bending toward the utricle is excitatory for that canal.

Question 11Vestibular Anatomy and Physiology

During a sustained constant-velocity head rotation, afferent firing from the canal initially rises and then declines toward baseline. What is this called?

  1. Sensory overload
  2. Canal paresis
  3. Vestibulo-ocular reflex
  4. Vestibular adaptation Correct answer.

Explanation

The cupula is elastic and gradually returns toward its neutral position while endolymph velocity decays, so the afferent response wanes during constant velocity. This adaptation explains why prolonged rotation is poorly perceived.

Question 12Vestibular Anatomy and Physiology

A patient lies supine with the head turned to the right. Which otolith organ is most strongly affected by this static tilt?

  1. The endolymphatic sac
  2. The left cochlear duct
  3. The utricle, whose macula is roughly horizontal in the upright head Correct answer.
  4. The right posterior canal

Explanation

The utricular macula lies approximately in the horizontal plane when the head is upright, so it is the principal sensor of static head tilt and horizontal linear acceleration. Turning the head reorients the utricle relative to gravity, changing its otolith load.

Question 13Vestibular Anatomy and Physiology

The three semicircular canals of one ear are oriented so that each canal is approximately parallel to which structure?

  1. The cochlear basal turn
  2. The saccular macula
  3. The eustachian tube
  4. A canal plane in the contralateral ear Correct answer.

Explanation

The canals are arranged in three roughly orthogonal planes, and each canal on one side is nearly parallel to a canal on the opposite side. This pairing lets the brain compare push-pull activity between coplanar canals.

Question 14Vestibular Anatomy and Physiology

Endolymph in the vestibular labyrinth is unusual because its ionic composition most closely resembles which of the following?

  1. Intracellular fluid Correct answer.
  2. Cerebrospinal fluid
  3. Seawater
  4. Plasma

Explanation

Endolymph is rich in potassium and low in sodium, resembling the intracellular milieu rather than typical extracellular fluid. This gradient drives potassium into hair cells through the mechanically gated channels.

Question 15Vestibular Anatomy and Physiology

Which brainstem structure receives the majority of primary vestibular afferents?

  1. The inferior olive
  2. The vestibular nuclei complex Correct answer.
  3. The red nucleus
  4. The dentate nucleus

Explanation

Primary vestibular fibers terminate mainly in the superior, lateral, medial and inferior vestibular nuclei at the pontomedullary junction. Some fibers also project to the cerebellum, but the nuclei are the principal relay.

Question 16Vestibular Anatomy and Physiology

Ampullary afferents from the horizontal canal are excited during rotation in which circumstance?

  1. Contralateral rotation, with endolymph leading the canal
  2. Any linear acceleration along the vertical axis
  3. Sustained constant velocity after the cupula has returned to rest
  4. Ipsilateral rotation, with endolymph lagging behind the canal Correct answer.

Explanation

When the head rotates toward a canal, inertia makes endolymph lag, which deflects the cupula toward the utricle and excites horizontal canal afferents. Rotation in the opposite direction produces the opposite cupular deflection and inhibition.

Question 17Vestibular Anatomy and Physiology

Which receptor type is surrounded by a calyx ending formed by a single afferent terminal?

  1. Type I vestibular hair cell Correct answer.
  2. Supporting cell
  3. Type II vestibular hair cell
  4. Outer cochlear hair cell

Explanation

Type I hair cells are flask-shaped and enclosed by a chalice-like calyx formed by a single afferent. Type II cells are cylindrical and contacted by ordinary bouton endings.

Question 18Vestibular Anatomy and Physiology

The vestibulo-ocular reflex stabilizes gaze during head movement by generating eye movements that are which of the following?

  1. Equal in velocity and same direction as the head movement
  2. Independent of head velocity
  3. Slower than the head movement and in the same direction
  4. Equal in velocity but opposite in direction to the head movement Correct answer.

Explanation

The reflex drives the eyes at a velocity approximately equal and opposite to head velocity, keeping the retinal image stable. This requires a short-latency three-neuron arc through the vestibular nuclei and ocular motor nuclei.

Question 19Vestibular Anatomy and Physiology

A clinician tilts a patient's head forward by about 30 degrees before performing a horizontal canal test. Why is this position used?

  1. To align the saccule with gravity
  2. To bring the horizontal canal into the horizontal plane Correct answer.
  3. To open the eustachian tube
  4. To compress the endolymphatic sac

Explanation

The horizontal canal lies tilted when the head is upright, so a forward tilt of roughly 30 degrees brings its plane close to horizontal. In that orientation rotation about the vertical axis is the optimal stimulus for the canal.

Question 20Vestibular Anatomy and Physiology

Which of the following best describes the mechanical role of the cupula during head rotation?

  1. It anchors the otoconia over the macula
  2. It acts as a flexible diaphragm deflected by endolymph flow Correct answer.
  3. It generates the endolymph current itself
  4. It secretes endolymph into the ampulla

Explanation

The cupula spans the ampulla as a gelatinous diaphragm, and endolymph flow bends it so that hair bundles in the crista are deflected. Its elasticity also returns it to the neutral position, producing adaptation.

Question 21Vestibular Anatomy and Physiology

A patient has lost function of the right horizontal canal. During rotation to the right, what pattern of afferent activity is expected from the two horizontal canals?

  1. Right canal firing rises while left canal firing falls
  2. Both canals decrease firing equally
  3. Right canal firing falls while left canal firing rises Correct answer.
  4. Both canals increase firing equally

Explanation

Rotation to the right excites the right horizontal canal and inhibits the left in a normal push-pull pattern. If the right canal is nonfunctional, its afferent firing cannot rise, so only the left canal's inhibitory drop and the resulting asymmetry remain.

Question 22Vestibular Anatomy and Physiology

After a unilateral vestibular nerve section, spontaneous nystagmus is typically directed toward which side in the acute phase?

  1. Toward the lesioned ear
  2. Alternating with each heartbeat
  3. Toward the intact ear Correct answer.
  4. Vertically downward only

Explanation

Loss of resting discharge from the lesioned side makes the intact side relatively more active, so the eyes drift toward the lesion and beat away toward the intact ear. This tonic imbalance underlies the acute spontaneous nystagmus.

Question 23Vestibular Anatomy and Physiology

Why does the vestibulo-ocular reflex remain accurate despite the very short time available for movement?

  1. It is driven by auditory feedback
  2. It uses a short-latency three-neuron arc through the brainstem Correct answer.
  3. It relies on slow cortical visual processing
  4. It depends on learned voluntary eye movements

Explanation

The reflex arc links the vestibular ganglion, vestibular nuclei and ocular motor nuclei with very few synapses, allowing responses within milliseconds. This speed is essential because retinal image motion of even a few degrees per second degrades vision.

Question 24Vestibular Anatomy and Physiology

The velocity storage mechanism in the vestibular system primarily does which of the following?

  1. Prolongs the vestibular signal beyond the mechanical time constant of the cupula Correct answer.
  2. Reduces the number of hair cells recruited
  3. Converts angular acceleration into otolithic signals
  4. Increases the stiffness of the cupula

Explanation

Central velocity storage extends the duration of the vestibular response well past the decay of cupular deflection. This prolongs nystagmus and improves the low-frequency performance of the vestibulo-ocular reflex.

Question 25Vestibular Anatomy and Physiology

A patient reports vertigo provoked by rolling over in bed, with brief torsional nystagmus. Which receptor population is most likely generating the abnormal signal?

  1. Utricular afferents
  2. Posterior semicircular canal afferents Correct answer.
  3. Cochlear afferents
  4. Saccular afferents

Explanation

Positional vertigo with brief torsional and vertical nystagmus typically reflects inappropriate excitation of a posterior canal, most often by displaced otoconia. The canal's afferents then signal rotation that is not actually occurring.

Question 26Vestibular Anatomy and Physiology

Which cranial nerve carries primary vestibular afferents from the labyrinth to the brainstem?

  1. The glossopharyngeal nerve
  2. The trigeminal nerve
  3. The vestibulocochlear nerve Correct answer.
  4. The facial nerve

Explanation

Vestibular hair cells synapse on bipolar ganglion cells whose axons travel in the eighth cranial nerve, which is why it is called the vestibulocochlear nerve. This nerve enters the brainstem at the pontomedullary junction and distributes fibers to the vestibular nuclei and cerebellum. Hearing fibers share the same nerve but occupy a separate division.

Question 27Vestibular Anatomy and Physiology

Blood supply to the vestibular nuclei and the eighth nerve arises mainly from which arterial system?

  1. The ophthalmic artery
  2. The anterior communicating artery
  3. The middle cerebral artery
  4. The vertebrobasilar system Correct answer.

Explanation

The vestibular nuclei lie in the pontomedullary region, which is irrigated by branches of the vertebrobasilar circulation, including the anterior inferior cerebellar artery and posterior inferior cerebellar artery. The inner ear itself is supplied by the labyrinthine artery, a branch of the anterior inferior cerebellar artery. This anatomy explains why vertebrobasilar ischemia can cause vertigo together with brainstem signs.

Question 28Vestibular Anatomy and Physiology

A lesion destroys the right vestibular nuclei while leaving the right labyrinth intact. Which change in the vestibulo-ocular reflex would be expected when the head is rotated to the right?

  1. Exaggerated rightward slow-phase eye velocity
  2. Reduced rightward slow-phase eye velocity Correct answer.
  3. Reversal of the rightward slow-phase direction
  4. Normal rightward slow-phase eye velocity

Explanation

Rightward head rotation excites the right horizontal canal, and that signal must pass through the right vestibular nuclei to drive the eyes leftward as a compensatory slow phase. Destroying those nuclei removes the relay for the excitatory right-sided drive, so the response to rightward rotation is weakened. The intact left canal still inhibits its ipsilateral side during the same rotation, but inhibition alone cannot generate a full response.

Question 29Vestibular Anatomy and Physiology

Which statement best describes the projection of the vestibular nuclei to the spinal cord?

  1. They project to the contralateral lumbar cord to control leg extensors
  2. They send fibers mainly to the ipsilateral cervical cord to control neck muscles Correct answer.
  3. They project diffusely to all spinal levels with no somatotopic order
  4. They send no descending fibers and influence posture only through the cerebellum

Explanation

The lateral and medial vestibulospinal tracts descend largely ipsilaterally, and the medial tract terminates predominantly in the cervical and upper thoracic cord. These projections adjust neck and axial muscle tone so the head is stabilized during body movement. The lateral tract extends further caudally to influence limb extensor tone.

Question 30Vestibular Anatomy and Physiology

A patient has a stable, complete loss of all vestibular function in both ears. Which combination of findings is most consistent with this bilateral deficit?

  1. Vertigo that is severe and constant at rest
  2. Spontaneous unidirectional nystagmus that persists for weeks
  3. Oscillopsia during head movement with a positive head impulse test bilaterally Correct answer.
  4. Normal vestibulo-ocular reflex gain with impaired smooth pursuit

Explanation

Bilateral loss abolishes the vestibulo-ocular reflex in both directions, so rapid head turns are not compensated and the visual world appears to slip, producing oscillopsia. The head impulse test is positive on both sides because corrective catch-up saccades appear after each thrust. Because the deficit is symmetric, there is no tonic imbalance and therefore no spontaneous nystagmus at rest.

Question 31Vestibular Pathology and Differential Diagnosis

Which clinical feature most strongly suggests that vertigo is peripheral rather than central in origin?

  1. Dysarthria and limb ataxia accompanying the vertigo
  2. Vertical downbeating nystagmus that does not suppress with visual fixation
  3. Direction-fixed horizontal nystagmus that suppresses with visual fixation Correct answer.
  4. Isolated skew deviation with normal head impulse testing

Explanation

Peripheral vestibular lesions typically produce unidirectional horizontal nystagmus that is inhibited by fixation and is accompanied by a positive head impulse test. Central lesions more often show direction-changing or vertical nystagmus, fixation failure, skew deviation, or long-tract neurological signs.

Question 32Vestibular Pathology and Differential Diagnosis

A patient reports brief spinning triggered by rolling over in bed and lasting under one minute, with no symptoms at rest. Which diagnosis fits best?

  1. Benign paroxysmal positional vertigo Correct answer.
  2. Vestibular neuritis
  3. Vestibular schwannoma
  4. Meniere disease

Explanation

BPPV is characterized by short-lived positional vertigo provoked by head movement and lasting seconds to under a minute, without spontaneous symptoms between episodes. The brief duration and strict positional trigger distinguish it from inflammatory, hydropic, or neoplastic causes.

Question 33Vestibular Pathology and Differential Diagnosis

Which combination of symptoms defines the classic attack of Meniere disease?

  1. Progressive bilateral hearing loss with ataxia and absent reflexes
  2. Sudden vertigo with facial palsy and ipsilateral hearing loss
  3. Episodic vertigo with fluctuating sensorineural hearing loss, tinnitus, and aural fullness Correct answer.
  4. Positional vertigo with normal audiometry and normal tympanometry

Explanation

Meniere disease is defined by recurrent spontaneous vertigo attacks lasting twenty minutes to hours, together with fluctuating low-frequency sensorineural hearing loss, tinnitus, and aural fullness in the affected ear. The coexistence of cochlear and vestibular symptoms is the key discriminator.

Question 34Vestibular Pathology and Differential Diagnosis

Which finding on head impulse testing is most consistent with a complete unilateral vestibular deafferentation?

  1. Reduced gain with overt corrective saccades toward the intact side Correct answer.
  2. Normal gain with no corrective saccades
  3. Normal gain with covert corrective saccades
  4. Hypermetric saccades in both directions

Explanation

A severe unilateral vestibular loss produces a reduced vestibulo-ocular reflex gain on impulses toward the affected side, with corrective saccades that bring the eyes back to the target. Covert saccades occur before the head stops, overt saccades after it stops, and both indicate loss.

Question 35Vestibular Pathology and Differential Diagnosis

A patient has acute continuous vertigo, nausea, and unidirectional horizontal nystagmus with a positive head impulse test on the right. Which diagnosis is most likely?

  1. Right posterior canal BPPV
  2. Brainstem infarction
  3. Bilateral vestibulopathy
  4. Right vestibular neuritis Correct answer.

Explanation

Acute sustained vertigo over days with spontaneous unidirectional nystagmus and an ipsilateral positive head impulse test is the classic picture of vestibular neuritis. The continuous time course and peripheral findings separate it from positional disorders and central lesions.

Question 36Vestibular Pathology and Differential Diagnosis

Which clinical sign is most characteristic of a superior semicircular canal dehiscence?

  1. Episodic vertigo lasting hours with low-frequency sensorineural loss
  2. Positive head impulse test on the affected side
  3. Direction-changing nystagmus with gaze fixation failure
  4. Sound- or pressure-induced vertigo with low-frequency conductive hearing loss Correct answer.

Explanation

A dehiscence of bone over the superior canal creates a third mobile window, producing sound- or pressure-evoked vertigo (Tullio phenomenon) and an apparent air-bone gap with normal reflexes. The low-frequency conductive pattern with intact stapedial reflexes is a hallmark.

Question 37Vestibular Pathology and Differential Diagnosis

A patient reports imbalance in the dark and oscillopsia while walking, with no vertigo at rest. Which diagnosis should be considered first?

  1. Bilateral vestibular hypofunction Correct answer.
  2. Posterior canal BPPV
  3. Acute vestibular neuritis
  4. Meniere disease

Explanation

Bilateral vestibular hypofunction causes chronic imbalance that worsens in low-light conditions and oscillopsia during head movement, because the vestibulo-ocular reflex is lost on both sides. The absence of acute vertigo reflects bilateral symmetry of the deficit.

Question 38Vestibular Pathology and Differential Diagnosis

Which feature distinguishes vestibular migraine from Meniere disease when both cause episodic vertigo?

  1. Vertigo lasting seconds triggered by head position
  2. Fluctuating low-frequency hearing loss during attacks
  3. Progressive unilateral hearing loss with reduced speech discrimination
  4. A history of migraine headaches with photophobia and phonophobia during attacks Correct answer.

Explanation

Vestibular migraine is diagnosed when recurrent vestibular symptoms occur in a patient with a migraine history and migraine features such as headache, photophobia, or phonophobia during at least some attacks. Hearing loss is not a defining feature, which helps separate it from Meniere disease.

Question 39Vestibular Pathology and Differential Diagnosis

A patient develops vertigo and unilateral hearing loss after a course of intravenous gentamicin. Which mechanism best explains the findings?

  1. Endolymphatic hydrops of the cochlea
  2. Demyelination of the vestibular nerve root
  3. Ototoxic damage to vestibular and cochlear hair cells Correct answer.
  4. Dislodged otoconia in the posterior canal

Explanation

Aminoglycosides are ototoxic and damage hair cells in both the vestibular and cochlear end organs, which can produce vertigo, imbalance, and hearing loss. Because the toxicity is often bilateral and progressive, symptoms may emerge after the exposure.

Question 40Vestibular Pathology and Differential Diagnosis

A patient with acute vertigo has normal head impulse testing, direction-changing nystagmus, and skew deviation. What is the most appropriate interpretation?

  1. Central lesion requiring urgent neuroimaging Correct answer.
  2. Meniere disease requiring a low-salt diet
  3. BPPV requiring a canalith repositioning maneuver
  4. Peripheral vestibular loss requiring vestibular suppressants

Explanation

A normal head impulse test combined with direction-changing nystagmus and skew deviation forms a central pattern that warrants urgent imaging to exclude stroke. The HINTS examination uses these three findings to separate central from peripheral causes.

Question 41Vestibular Pathology and Differential Diagnosis

Which test result best supports a diagnosis of superior canal dehiscence rather than otosclerosis in a patient with a low-frequency air-bone gap?

  1. Intact acoustic reflexes with a conductive pattern and vestibular-evoked myogenic potential threshold lowering Correct answer.
  2. Carhart notch at 2 kHz on bone conduction
  3. Absent acoustic reflexes with a conductive pattern
  4. Type B tympanogram with middle-ear effusion

Explanation

In canal dehiscence the third mobile window lowers vestibular-evoked myogenic potential thresholds and preserves acoustic reflexes despite the conductive-appearing audiogram. Otosclerosis instead typically reduces acoustic reflex amplitudes and lacks the vestibular-evoked potential changes.

Question 42Vestibular Pathology and Differential Diagnosis

A patient describes recurrent attacks of spinning lasting 20 to 60 minutes with roaring tinnitus and ear fullness, and audiometry shows a low-frequency sensorineural loss that fluctuates. Which management step is most appropriate initially?

  1. High-dose corticosteroids for presumed vestibular neuritis
  2. Daily betahistine with immediate surgical decompression
  3. Dietary salt restriction with diuretic therapy and vestibular suppressants for acute attacks Correct answer.
  4. Canalith repositioning maneuver of the affected posterior canal

Explanation

Initial management of Meniere disease is conservative, combining dietary salt restriction, diuretics, and short-term vestibular suppressants or antiemetics during attacks. Surgery is reserved for refractory cases after medical therapy fails.

Question 43Vestibular Pathology and Differential Diagnosis

A patient has positional vertigo and a positive Dix-Hallpike test on the left with upbeating torsional nystagmus after a brief latency. Which canal is affected?

  1. Left posterior canal Correct answer.
  2. Right posterior canal
  3. Right anterior canal
  4. Left horizontal canal

Explanation

A positive Dix-Hallpike test on the left with upbeating and torsional nystagmus indicates involvement of the left posterior canal. The latency and brief duration reflect otoconia moving within that canal.

Question 44Vestibular Pathology and Differential Diagnosis

Which feature most reliably distinguishes vestibular paroxysmia from BPPV?

  1. Attacks accompanied by progressive unilateral hearing loss
  2. Attacks provoked only by lying down or rolling over
  3. Attacks accompanied by fluctuating hearing loss
  4. Brief attacks lasting seconds to minutes occurring many times per day without a positional trigger Correct answer.

Explanation

Vestibular paroxysmia causes frequent, very brief spells of vertigo that are not strictly positional and may respond to carbamazepine. BPPV attacks are consistently provoked by specific head movements and are less frequent.

Question 45Vestibular Pathology and Differential Diagnosis

A patient with a vestibular schwannoma reports gradually worsening imbalance and unilateral hearing loss. Which pathophysiological explanation best fits the gradual onset?

  1. Acute inflammation of the vestibular nerve
  2. Displacement of otoconia into the posterior canal
  3. Rapid endolymphatic pressure increase
  4. Slow compression and demyelination of the eighth nerve with central compensation Correct answer.

Explanation

Vestibular schwannomas grow slowly, so the gradual loss of vestibular input allows central compensation and produces progressive imbalance rather than acute vertigo. The tumor also compresses the cochlear nerve, causing unilateral hearing loss.

Question 46Vestibular Pathology and Differential Diagnosis

Which finding on videonystagmography most suggests a peripheral rather than central cause of spontaneous nystagmus?

  1. Pure vertical nystagmus without fixation suppression
  2. Nystagmus that increases with visual fixation
  3. Nystagmus that decreases with visual fixation and is suppressed by convergence Correct answer.
  4. Rebound nystagmus after sustained gaze

Explanation

Peripheral spontaneous nystagmus is inhibited by visual fixation and by convergence, reflecting the loss of tonic vestibular input. Central nystagmus often fails to suppress with fixation and may be purely vertical or show rebound.

Question 47Vestibular Pathology and Differential Diagnosis

A patient reports vertigo that begins within seconds of turning the head and lasts about 30 seconds, with a positive supine roll test showing geotropic horizontal nystagmus. Which condition is most likely?

  1. Vestibular neuritis
  2. Posterior canal BPPV
  3. Horizontal canal BPPV Correct answer.
  4. Superior canal dehiscence

Explanation

Horizontal canal BPPV is provoked by supine roll testing and produces horizontal geotropic nystagmus that beats toward the ground when the affected ear is down. The brief latency and short duration are typical of canalithiasis.

Question 48Vestibular Pathology and Differential Diagnosis

Which clinical scenario most appropriately raises suspicion for vertebral artery dissection as a cause of acute vertigo?

  1. Vertigo with bilateral hearing loss after diuretic use
  2. Vertigo with neck pain and headache after chiropractic manipulation Correct answer.
  3. Vertigo with brief positional triggers and no headache
  4. Vertigo with fluctuating hearing loss and aural fullness

Explanation

Neck pain or headache accompanying vertigo after neck manipulation or trauma should raise concern for vertebral artery dissection, which can cause brainstem ischemia. Vascular imaging is indicated because anticoagulation or antiplatelet decisions depend on the diagnosis.

Question 49Vestibular Pathology and Differential Diagnosis

A patient has persistent vertigo and nystagmus that changes direction with gaze, plus limb ataxia and dysarthria. Which localization is most likely?

  1. Labyrinth
  2. Cerebellar or brainstem lesion Correct answer.
  3. Superior vestibular nerve
  4. Posterior semicircular canal

Explanation

Gaze-evoked direction-changing nystagmus with ataxia and dysarthria localizes to the central nervous system, most often the cerebellum or brainstem. Peripheral lesions produce direction-fixed nystagmus without long-tract signs.

Question 50Vestibular Pathology and Differential Diagnosis

Which patient history feature most strongly supports a diagnosis of persistent postural-perceptual dizziness?

  1. Progressive unilateral hearing loss with facial numbness
  2. Episodic vertigo with hearing fluctuation lasting hours
  3. Chronic unsteadiness and visual sensitivity that began after an acute vestibular event and persists for months Correct answer.
  4. Brief spinning spells triggered by rolling over in bed

Explanation

Persistent postural-perceptual dizziness is a chronic functional disorder that often follows an acute vestibular event and is characterized by persistent unsteadiness, visual sensitivity, and worsening in complex visual environments. Symptoms last months and do not fit a structural episodic pattern.