Peripheral vestibular syndrome – benign paroxysmal positional vertigo, Meniere’s disease, differential diagnosis.
Peripheral vestibular syndrome refers to a group of disorders arising from pathology of the peripheral vestibular system, which includes the inner ear labyrinth and the vestibular nerve before it enters the brainstem. Peripheral vertigo comes from the inner ear and causes severe spinning with hearing problems but no other neurological signs, while central vertigo comes from the brain and usually has milder spinning with neurological symptoms but rarely affects hearing.
A. Benign Paroxysmal Positional Vertigo (BPPV)
1. Definition: A disorder characterized by brief episodes of intense vertigo triggered by changes in head position, due to displaced otoconia (calcium carbonate crystals) from the utricular macula into one of the semicircular canals (SCCs). It is benign (not life-threatening) and paroxysmal (sudden, short).
2. Etiopathogenesis
- Canalithiasis (most common,): The otoconia (canaliths) are free-floating within the endolymph of the SCC. Head movement causes the crystals to move, creating drag on the endolymph and abnormally stimulating the cupula, leading to a false sense of rotation.
- Cupulolithiasis (less common): The otoconia are attached to the cupula of the SCC. This makes the cupula gravity- sensitive, triggering vertigo when the head is in the provoking position.
- Risk Factors: Advanced age, head trauma, Vestibular Neuritis, and prolonged bed rest. Otoliths most commonly enter the posterior semicircular canal
3. Classification: BPPV is classified by the affected semicircular canal:
- Posterior SCC BPPV (most common): Diagnosed by the Dix-Hallpike test.
- Horizontal SCC BPPV (second most common): Diagnosed by the Roll test.
- Anterior SCC BPPV (rare).
4. Clinical Picture
- Vertigo: Sudden-onset, intense spinning sensation that lasts minute (typically seconds).
- Trigger: Always provoked by a change in head position.
- No hearing loss or tinnitus (key distinction from Ménière’s)
- Associated Symptoms: Often accompanied by nausea and occasionally vomiting.
- Positional nystagmus (rotatory and vertical for posterior canal, horizontal for lateral canal) is observed upon reaching the provoking position. It has a latency of 5-10 seconds, crescendos in intensity, decreases (decrescendos), and fatigues upon repetition. No neurological signs.
5. Paraclinical and Radiological Examinations
- Diagnostic Test: Dix-Hallpike Maneuver (for Posterior SCC BPPV) or Supine Roll Test (for Horizontal SCC BPPV). A positive test reproduces the patient's vertigo and elicits the characteristic nystagmus.
- Audiometry: Normal (BPPV does not cause hearing loss).
- Radiology (MRI/CT): Not needed for primary diagnosis; used only to rule out central causes if the nystagmus is atypical or if neurological signs are present.
6. Treatment Options