Vestibular paroxysmia

Vestibular paroxysmia describes a clinical syndrome of sudden and stereotyped episodes of vertigo-type symptoms which usually last for less than one minute, often attributed to being a nerve compression syndrome affecting the vestibular nerve.

Epidemiology

Vestibular paroxysmia most commonly manifests in two age peaks - one peak in the young and another larger peak in middle-aged adults ^1-3 - with each peak demonstrating a different etiological basis for the same clinical syndrome ^2,3.

Clinical presentation

The clinical diagnostic criteria for vestibular paroxysmia are defined by the Classification Committee of the Bárány Society as ¹:

• at least ten attacks of spontaneous vertigo (spinning or non-spinning)
  • probable diagnosis: at least five attacks
• duration less than 1 minute
  • probable diagnosis: less than 5 minutes
• stereotyped phenomenology
• response to a treatment with carbamazepine/oxcarbazepine
• not better accounted for by another diagnosis

Pathology

The leading hypothesis considers that vestibular paroxysmia is caused by irritation of the vestibular nerve leading to hyperactivity of the nerve and the subsequent clinical syndrome ^2-4. This irritation is most commonly caused by compression from a nearby blood vessel, similar to the pathogenesis of other nerve compression syndromes such as trigeminal neuralgia, nervus intermedius neuralgia, glossopharyngeal neuralgia, and vagoglossopharyngeal neuralgia. In addition to being attributable to a vascular structure, rarely vestibular paroxysmia can also occur due to compression and irritation from other structures, such as an arachnoid cyst or tumor ^2,3.

The most commonly (75%) involved artery is a loop of the anterior inferior cerebellar artery, and the site of neurovascular compression can be anywhere along the ~10 mm vestibular nerve transition zone from the brainstem ^2-4. In-keeping with the bimodal age peaks in affected patients, it has been postulated that in patients affected at a younger age, congenital vascular anomalies are the most likely source of compression and subsequent irritation of the vestibular nerve, while in patients in their middle-age, compression and subsequent irritation develops due to aberrant vascular anatomical changes (e.g. vessel lengthening or widening) caused by age-related progressive atherosclerotic and hypertensive changes ^2,3.

Radiographic features

The main role of imaging is to identify the cause of vestibular paroxysmia, which is nearly always a vascular loop.

MRI

MRI is the imaging modality of choice for identifying the site of neurovascular compression. In particular, constructive interference in steady-state (CISS) (a heavily T2 weighted sequence with thin sections) and 3D time-of-flight sequences have been found to be the most useful to observe the vestibular nerve and the offending irritating blood vessel respectively ^2-4.

Treatment and prognosis

Management can involve pharmacotherapy (e.g. carbamazepine or oxcarbazepine), which is first-line and generally very effective, or neurosurgical intervention (e.g. microvascular decompression) ^1-3,5.

History and etymology

The condition was first defined by Thomas Brandt and Marianne Dieterich, German neurologists, in their 1994 seminal paper ⁶.