Vestibular paroxysmia (VP) is a rare vertigo syndrome characterized by recurrent, brief attacks of vertigo. The disorder is typically caused by neurovascular compression of the Vestibulocochlear nerve[^2], but may also arise secondarily from space-occupying lesions in the Cerebellopontine angle. Idiopathic cases without an identifiable cause also occur [^1].
Epidemiology
Vestibular paroxysmia is a rare disorder. In a specialized dizziness center, it accounts for approximately 3 % of diagnoses. The mean age at onset is between 47 and 51 years, with both sexes affected at approximately equal rates. Cases in childhood are very rare but show symptoms similar to those in adults[^1].
Symptoms
The main symptoms of vestibular paroxysmia are frequent, brief attacks of spinning or rocking vertigo with gait or postural instability, lasting seconds to minutes. The attacks usually occur spontaneously, but in some patients they can be triggered by certain head movements or positions. Hyperventilation can also provoke attacks and nystagmus. In extreme cases, up to 70 attacks per day may occur[^3].
Unilateral auditory symptoms such as tinnitus or hyperacusis may occur concomitantly, either during the attacks or during the attack-free intervals. Nausea, vomiting, loss of consciousness, or falls, however, are atypical. In rare cases, vestibular paroxysmia may be combined with other symptoms such as Hemifacial spasm or Trigeminal neuralgia if adjacent cranial nerves are also affected.
Pathophysiology
The vertigo attacks are thought to be caused by compression of the vestibular portion of the vestibulocochlear nerve, analogous to other neurovascular compression syndromes such as trigeminal neuralgia or hemifacial spasm[^2]. The compression may lead to partial demyelination of the axons, resulting in ephaptic discharges (pathological interaxonal transmission). These may be triggered by arterial pulsations or sensory input during head movements. The proximal portion of the nerve ensheathed by oligodendrocytes (the root entry zone) appears to be particularly susceptible[^1].
Diagnosis
The diagnosis is based primarily on the typical history of brief, frequent attacks of vertigo. The diagnostic criteria were established by the Bárány Society and distinguish between "definite vestibular paroxysmia" and "probable vestibular paroxysmia" [^4].
Imaging
Imaging using high-resolution MRI sequences (e.g., CISS/FIESTA) can demonstrate neurovascular compression of the vestibulocochlear nerve. However, such contact is also found in a significant proportion of healthy control subjects (up to 55 %) and therefore, by itself, is not diagnostic of symptomatic vestibular paroxysmia[^1]. Imaging of the brainstem and inner ear is mandatory to rule out secondary causes.
Treatment
Conservative
Conservative treatment of vestibular paroxysmia is based primarily on sodium channel blockers such as carbamazepine or oxcarbazepine[^1].
Surgical
Microvascular decompression is an option for patients with vestibular paroxysmia in whom drug therapy is not tolerated or is insufficiently effective and in whom MRI demonstrates a neurovascular conflict involving the vestibulocochlear nerve.
