benign positional vertigo

**Pathophysiology:** Calcium carbonate crystals (otoconia) dislodge from the utricle and migrate into a semicircular canal (posterior canal ~85-90%; horizontal canal ~10%; anterior rare). Canalithiasis is the favored mechanism: with head movement, the free-floating debris moves with gravity, causing abnormal endolymph flow and cupular deflection, so the brain senses rotation that does not match actual head movement. Cupulolithiasis (debris adherent to the cupula) is an alternative mechanism. Risk factors: age (peak 50-70), female sex, head trauma, vestibular neuritis, prolonged bed rest, migraine, and osteoporosis/vitamin D deficiency.

**Clinical presentation:** - Brief episodes of intense rotatory vertigo lasting seconds to <1 minute. - Triggered by head position changes: rolling over in bed, looking up, bending over. - Nausea is common. Vomiting can occur. - NO hearing loss, tinnitus, aural fullness, or focal neurologic deficits. Their presence suggests another diagnosis.

**Diagnosis:** - Dix-Hallpike maneuver (posterior/anterior canal): the patient moves from sitting to supine with the head turned 45° and extended. A positive test reproduces vertigo with a characteristic torsional, upbeating nystagmus. The nystagmus has a latency of a few seconds, lasts <1 min, and fatigues with repeat testing. - Supine roll test (horizontal canal): produces horizontal nystagmus, either geotropic or apogeotropic. - Imaging is generally not needed if the presentation is typical.

**Differential and board distinctions:** - Central vertigo (cerebellar or brainstem stroke, tumor, MS): vertical or purely horizontal nystagmus that does not fatigue, has no latency, and does not suppress with fixation. Other findings are ataxia, diplopia, and dysarthria. - Vestibular neuritis: acute, continuous vertigo lasting days, with no hearing loss. Labyrinthitis is the same but with hearing loss. - Ménière disease: episodic vertigo lasting minutes to hours, with tinnitus, aural fullness, and fluctuating low-frequency sensorineural hearing loss (endolymphatic hydrops). - Vertebrobasilar insufficiency: vertigo with other brainstem signs. - Vestibular migraine: episodes of vertigo with migrainous features.

**Treatment:** - First-line: canalith repositioning maneuvers. The Epley maneuver is used for posterior canal BPPV. The Semont maneuver is an alternative. For horizontal canal BPPV, use the Lempert (barbecue roll) or Gufoni maneuver. - Vestibular suppressants (meclizine, benzodiazepines) are NOT recommended for definitive treatment. They may be used briefly for severe nausea. - Surgery (posterior canal occlusion) is reserved for rare refractory cases. - The recurrence rate is high (~50% within 5 years). The condition is self-limited in many patients, resolving over weeks to months.

**High-yield pearls:** - Short, positional episodes without hearing loss indicate BPPV. - Dix-Hallpike produces latency, fatigability, torsional upbeat nystagmus, and reproducible vertigo. - Treat with the Epley maneuver rather than medication.