BPPV

**Pathophysiology:** Calcium carbonate crystals (otoconia) from the utricle dislodge and enter a semicircular canal (canalithiasis), most commonly the posterior canal (~85-95%), then lateral/horizontal (~5-15%), and rarely anterior. With head movement, the free-floating debris moves with gravity, causing endolymph flow (a "plunger" effect) that deflects the cupula and gives a false sense of rotation. Less commonly, debris adheres to the cupula (cupulolithiasis). Risk factors: older age, head trauma, prior vestibular neuritis/labyrinthitis, prolonged bed rest, migraine, and osteoporosis/vitamin D deficiency. Women are affected more often than men.

**Clinical presentation:** - Brief episodes of vertigo (typically <1 minute, usually 10-30 seconds) triggered by specific head movements: rolling over in bed, looking up, bending over. - Nausea is common. Vomiting can occur. - NO hearing loss, tinnitus, aural fullness, or other neurologic deficits. These suggest another diagnosis (Meniere disease, labyrinthitis, central cause). - Between episodes the patient is typically asymptomatic or has mild imbalance.

**Diagnosis:** - **Dix-Hallpike maneuver** (posterior/anterior canal): patient moves from sitting to supine with the head turned 45° and extended below horizontal. Positive test: vertigo plus rotatory (torsional, upbeating) nystagmus toward the affected (down-facing) ear, with latency of a few seconds, then fatigability (it diminishes with repetition) and adaptation. Duration is <1 min. - **Supine roll test** (lateral canal): horizontal nystagmus, geotropic (more common) or apogeotropic. - Imaging is not needed if the presentation and exam are typical. Consider MRI if there are atypical features (central signs, direction-changing/vertical downbeat nystagmus without latency or fatigue, severe headache, new neurologic findings, no response to treatment).

**Differential (key board distinctions):** - Central vertigo (cerebellar/brainstem stroke, tumor, MS): persistent, other neurologic signs, vertical nystagmus, no fatigability. - Vestibular neuritis: acute, continuous vertigo lasting days, no hearing loss; positive head impulse test abnormalities. - Labyrinthitis: same as vestibular neuritis plus hearing loss. - Meniere disease: episodic vertigo lasting minutes to hours, with unilateral low-frequency sensorineural hearing loss, tinnitus, and aural fullness (endolymphatic hydrops). - Vestibular migraine: episodic vertigo with migraine features.

**Treatment:** - **Canalith repositioning maneuvers** are first-line: **Epley maneuver** (posterior canal), Semont maneuver (alternative). For lateral canal BPPV: Gufoni or barbecue (Lempert) roll maneuver. - Success is high (~80-90%) after 1-3 treatments. - Vestibular suppressants (meclizine, benzodiazepines) are NOT recommended for routine treatment. They don't treat the cause and may impair compensation, though they can be used briefly for severe nausea. - Recurrence is common (~50% within 5 years). Surgery (posterior canal occlusion) is reserved for rare refractory cases.

**High-yield pearls:** - Brief, positional vertigo + normal hearing + positive Dix-Hallpike = BPPV. - Posterior canal is the most common site. - Benign means it is not life-threatening, and it often resolves spontaneously within weeks to months. - Counsel on fall risk, especially in older adults.