What are the causes and risk factors for benign paroxysmal positional vertigo (BPPV)?

Causes of BPPV

BPPV is caused by dislodged calcium carbonate crystals (otoconia) that break free from the utricle and migrate into the semicircular canals, creating abnormal stimulation through either canalithiasis (free-floating particles) or cupulolithiasis (debris attached to the cupula). 1

Primary Pathophysiologic Mechanism

The fundamental cause involves otoconia—tiny calcium carbonate crystals normally anchored in the utricle—becoming "unglued" and floating into the semicircular canals through two distinct mechanisms 1:

• Canalithiasis (most common): Free-floating otoconia collect near the cupula of the affected canal, causing inertial changes and abnormal vestibular stimulation when the head moves in the plane of that canal 2
• Cupulolithiasis: Otoconial debris directly attaches to the cupula, causing displacement and abnormal stimulation 2

The posterior semicircular canal is affected in 85-95% of cases, while the lateral (horizontal) canal accounts for 5-15% of cases 2, 1. The posterior canal's gravity-dependent position when supine partly explains its predominance 3.

Identifiable Risk Factors and Causes

Idiopathic (Most Common)

• Most BPPV cases remain idiopathic with no identifiable precipitating cause 3

Head Trauma

• Posttraumatic BPPV occurs relatively commonly after trauma or traumatic brain injury 2
• Posttraumatic BPPV is significantly more refractory, requiring repeated physical treatments in up to 67% of cases compared to 14% in nontraumatic forms 2
• May be bilateral in rare instances 2

Age-Related Degeneration

• BPPV is significantly more common in older adults over 50 1
• Age-related degeneration of the otolithic membrane likely contributes to otoconial detachment 1

Prolonged Bed Rest and Sleep Position

• Lying in bed for long periods is an explicit causative factor 3
• Habitually sleeping on one side increases the risk of developing BPPV on that same side 3
• The posterior canal's gravity-dependent position when supine facilitates otoconial migration 3

Associated Inner Ear Disorders

• BPPV occurs in conjunction with or as sequelae to other vestibular disorders including Meniere's disease and vestibular neuritis 2
• Other inner ear problems can precipitate otoconial displacement 3

Metabolic and Systemic Conditions

• Diabetes is associated with increased BPPV risk 3
• Osteoporosis may contribute to otoconial fragmentation 3
• Metabolic conditions affecting calcium metabolism 1

Migraine

• Migraine is a recognized risk factor for BPPV development 1, 3

Post-Surgical

• Post-surgical procedures can precipitate BPPV 1

Important Clinical Pitfalls

Multiple Concurrent Diagnoses

• Clinicians must consider the possibility of more than one vestibular disorder being present in patients who don't clearly have symptoms of a single vestibular entity 2
• BPPV can coexist with Meniere's disease, vestibular neuritis, or CNS disorders 2

CNS Disorders Mimicking BPPV

• Multiple sclerosis patients with acute vertigo may have BPPV with positive Dix-Hallpike maneuver and successful response to repositioning 2
• Patients with underlying CNS disorders can still be successfully diagnosed and treated with conventional BPPV methods 2

Failure to Respond to Treatment

• Failure to respond to conservative management such as canalith repositioning should raise concern that the underlying diagnosis may not be BPPV 2
• Refractory cases warrant reassessment for alternative diagnoses 4