Vestibular paroxysmia

Vestibular paroxysmia

What is vestibular paroxysmia?

In the literature, vestibular paroxysmia is also referred to as disabling positional vertigo, vascular loop syndrome, or microvascular compression syndrome. It is a chronic vestibular disorder. Numerous short-lasting episodes of vertigo characterize it, believed to be caused by a blood vessel’s compression of the cochleovestibular nerve. Other microvascular compression syndromes include trigeminal neuralgia and hemifacial spasm.

Vestibular paroxysmia

How common is it?

Vestibular paroxysmal is a rare condition of which the exact prevalence is not known. It occurs in less than 4% vertigo and dizziness patients. The mean age of occurrence is around 50 years. It may occur in children most. In younger patients, the symptoms may sometimes spontaneously resolve.

What causes vestibular paroxysmia?

Vestibular paroxysmia is a controversial syndrome. A blood vessel, which forms a loop around the vestibular branch of the cochleovestibular nerve (VIII cranial nerve) is believed to be responsible. The blood vessel causes pressure on the nerve and short circuits in the nerve conduction. It is not clear which patients will develop symptoms. Still, it seems that atherosclerosis of blood vessels, damage to the nerve such as in previous vestibular neuritis, and arachnoiditis may predispose patients.

Vestibular paroxysmia
Blood vessel overlying the white cochleovestibular nerve ( black arrow). With permission from Prof Michael Strupp, Munich.

How does it present?

Vestibular paroxysmia presents with attacks of short-lasting vertigo, usually a few seconds (quick spins) to a few minutes at most. The number of attacks can vary between a few per year or up to 30 or more per day. Attacks occur spontaneously but may, in some cases, certain head positions or exercises may trigger it. It may lead to motion intolerance. When attacks occur during walking, a patient may lose balance. Attacks are usually self-limiting. It can also be accompanied by auditory symptoms such as hyperacusis, tinnitus, and even hearing loss. Sometimes due to Its proximity, the facial nerve may be involved. In these cases with additional symptoms, it may be possible to localise the involved side.

Which other conditions should be considered?

Numerous conditions may be mistaken for vestibular paroxysmia. These include:

And when evoked by positioning:

During attack-free intervals, patients can still be bothered by tinnitus and hearing loss. With examination, nystagmus can sometimes be seen. If the direction of the nystagmus reverses with hyperventilation, it is suggestive of the condition. Hearing tests, auditory brainstem evoked responses (ABR), and video nystagmography (VNG) may be ordered. An MRI can support the diagnosis of a vascular loop but, unfortunately, is not very specific.

Vascular loop
A vascular loop seen on MRI (yellow arrow).

Diagnosing vestibular paroxysmia

Although MRI often shows a vascular loop, all humans have blood vessels around nerves. It does not confirm the diagnosis. It is more often performed to exclude other structural lesions that may be responsible for symptoms. These lesions include vestibular schwannoma, arachnoid cysts, plaques seen in multiple sclerosis, and abnormal blood vessels.

Nystagmus, usually beating towards the affected side, may be seen during an attack if a patient is seen. In symptom-free periods, nystagmus will usually beat in the opposite direction. When the patient is asked to hyperventilate, which also occurs during exercise, nystagmus may be provoked. Hearing and facial nerve function tests may help to localize the affected side.

Vestibular paroxysmia
The question is whether the artery indicated by the yellow arrow is responsible for the symptoms?

How is vestibular paroxysmia treated

The first line of treatment should always be medical, and a positive response to treatment may be seen as diagnostic in a patient who fulfills the criteria of vestibular paroxysmia. In some selected cases, a surgical procedure may be of value. The Jannetta decompression procedure, named after neurosurgeon, Dr. Jannetta was initially described for trigeminal neuralgia. It is rarely performed for vestibular paroxysmia. The blood vessel is delicately separated from the nerve, and a piece of Teflon is then inserted between the blood vessel and the nerve. Although it may cure vertigo, it does not help with tinnitus. Decompression surgery is risky and not consistently successful. Reserve it as a last resort.