Utricle Otoconia Break Free From the Macula
Aging or trauma loosens calcium carbonate crystals from their gel bed.
- CaCO3: Crystal material (calcite otoconia)
- 3–30 µm: Typical size (per crystal)
- Age / trauma: Common cause (degeneration of macula)
- ~2.4%: Prevalence (lifetime risk)
Why crystals detach
Placeholder: gel matrix degeneration frees otoconia over time.
Loose Crystals Drift Into the Posterior Canal
Gravity pulls dislodged debris into the most dependent canal.
- Posterior: Most affected canal (~90% of cases)
- Utricle → canal: Migration path (via common crus)
- Free clot: Debris form (canalithiasis)
- Seconds: Onset delay (after head shift)
Migration path
Placeholder: crystals settle by gravity into the canal arc.
Endolymph Drag Bends the Cupula Off-Axis
Crystal weight in the canal creates abnormal fluid drag on the cupula.
- Motion sensor: Cupula role (normally symmetric)
- Heavy debris: Deflection cause (cupulolithiasis variant)
- False: Signal type (no true rotation)
- 1–5 s: Latency (before nystagmus)
Fluid mechanics
Placeholder: crystal mass amplifies endolymph flow on tilt.
Position Change Triggers Spinning Vertigo
Head tilt produces brief but intense rotational vertigo and nystagmus.
- <60 s: Duration (per episode)
- Head tilt: Trigger (rolling in bed, looking up)
- Nystagmus: Hallmark sign (torsional-upbeating)
- Vertigo: Symptom (spinning sensation)
Clinical picture
Placeholder: brief severe vertigo follows specific head movements.
Canalith Repositioning Guides Crystals Home
Sequential head maneuvers move debris back to the utricle.
- Epley: Standard maneuver (canalith repositioning)
- ~80%: Success rate (after one session)
- Gravity-guided: Mechanism (sequential rotation)
- ~15%: Recurrence (within one year)
Treatment logic
Placeholder: gravity carries crystals out via timed head turns.
Placeholder: maneuvers restore normal cupula function quickly.