What are peripheral vestibular disorders?

Peripheral Vestibular Disorders

Peripheral vestibular disorders are conditions affecting the inner ear and vestibular nerve that cause vertigo, dizziness, and balance problems due to dysfunction in the peripheral vestibular system rather than central nervous system pathways. 1

Major Types of Peripheral Vestibular Disorders

Benign Paroxysmal Positional Vertigo (BPPV)

• Most common peripheral vestibular disorder characterized by brief episodes of vertigo triggered by specific head positions 2, 1
• Caused by calcium carbonate crystals (otoconia) becoming dislodged from their normal position and floating in the semicircular canals 2
• Symptoms include intense spinning sensations lasting seconds to minutes, nausea, vomiting, and disorientation 2
• Diagnosed through bedside testing such as the Dix-Hallpike test or supine roll test 2
• Treatment involves repositioning maneuvers with high success rates (around 80%) with only 1-3 treatments 2, 3

Vestibular Neuritis/Labyrinthitis

• Third most common peripheral vestibular disorder 4
• Presents with sudden severe vertigo lasting >24 hours with profound nausea and vomiting 1, 5
• Often attributed to viral infections (herpes simplex type 1 reactivation) or ischemia of the anterior vestibular artery 6, 4
• Characterized by acute unilateral vestibulopathy leading to vestibular tone imbalance 3
• Treatment includes symptomatic therapy, corticosteroids, and vestibular rehabilitation 6, 4

Menière's Disease

• Features episodic attacks of vertigo with fluctuating hearing loss, tinnitus, and aural fullness 1, 7
• Episodes are spontaneous rather than positionally triggered and typically last hours 1
• Endolymphatic hydrops can be visualized by high-resolution MRI after transtympanic gadolinium injection 6
• High-dosage and long-term prophylactic treatment with betahistine appears effective 6
• Mechanism likely involves increasing inner ear blood flow 6

Vestibular Paroxysmia

• Well-established entity characterized by brief, recurrent episodes of vertigo 6, 7
• Thought to be caused by neurovascular compression of the vestibular nerve 3
• Carbamazepine is the treatment of first choice 6, 7
• Diagnosis requires response to treatment with a sodium channel blocker 7

Superior Canal Dehiscence Syndrome (SCDS)

• Caused by a defect in the bone covering the superior semicircular canal 1
• Presents with pressure-induced vertigo rather than position-induced vertigo 2
• May present with conductive hearing loss due to lower bone-conducted thresholds 2
• Diagnosed via computed tomography of temporal bones or vestibular evoked myogenic potential testing 2
• Best current treatment option is canal plugging 6

Bilateral Vestibulopathy

• Characterized by loss or impairment of function in both vestibular nerves and/or labyrinths 3
• Can be diagnosed by head-impulse test, caloric irrigation, and vestibular-evoked myogenic potentials 6
• A subtype called cerebellar ataxia, neuropathy, and vestibular areflexia syndrome has been described 6
• Requires significantly reduced vestibular function for diagnosis 7
• Treatment primarily involves balance training 6

Differentiating Peripheral from Central Vestibular Disorders

Key Distinguishing Features

• Nystagmus findings that suggest central causes include downbeating nystagmus without torsional component, direction-changing nystagmus without head position changes, and baseline nystagmus without provocative maneuvers 2
• Central causes typically have nystagmus that doesn't fatigue and isn't easily suppressed by gaze fixation 2
• Peripheral disorders usually respond to repositioning maneuvers or vestibular rehabilitation, while failure to respond may indicate central pathology 2

Common Central Causes of Vertigo

• Vestibular migraine: attacks lasting minutes to hours with migraine history and photophobia 1
• Brainstem/cerebellar stroke: can mimic peripheral vestibular disorders but often has additional neurological findings 2, 1
• Multiple sclerosis: may present with fluctuating bilateral hearing loss alongside vertigo 1

Other Conditions That May Mimic Peripheral Vestibular Disorders

• Cervical vertigo: associated with degenerative cervical spine disease, triggered by head rotation relative to body while upright 2, 1
• Postural hypotension: causes dizziness when moving from supine to upright position 2, 1
• Medication side effects: various medications including anticonvulsants, antihypertensives, and cardiovascular medications can cause vertigo 2, 1
• Psychological disorders: panic disorder, anxiety disorder, or agoraphobia may present with lightheadedness and dizziness 2, 1

Clinical Approach to Diagnosis

• Consider timing and triggers: brief episodes triggered by head position changes suggest BPPV, while spontaneous episodes lasting hours suggest Menière's disease 1
• Assess for associated symptoms: hearing loss may indicate Menière's disease, while visual symptoms may suggest central causes 1
• Evaluate nystagmus characteristics: direction, duration, fatigability, and response to visual fixation 2
• Consider comorbidities that may modify management: impaired mobility, CNS disorders, lack of home support, and increased risk of falling 2

Treatment Considerations

• Treatment depends on the specific underlying disorder 3
• Physical therapy plays a crucial role in most peripheral vestibular disorders 5, 3
• Specific repositioning maneuvers for BPPV based on the canal involved 3
• Medication may be symptomatic or causative depending on the disorder 3
• Surgery may be indicated for specific conditions like superior canal dehiscence 3
• Psychotherapeutic measures may be needed for secondary functional dizziness 3