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Vestibular Paroxysmia

Another very rare cause of dizziness is vestibular paroxysmia. In this condition, it is thought that nearby arteries pulsate against the balance nerve, causing brief interruptions in functioning, resulting in intense episodes of vertigo lasting seconds. While it is well established that this proposed mechanism can cause dysfunction of other cranial nerve as they traverse a space in the head called the cerebellopontine angle (such as the facial nerve, i.e. hemifascial spasm), it’s more controversial if it can cause vertigo. Symptoms can be precipitated by hyperventilation, and workup includes an MRI, as certain heavily T2 weighted sequences can show a blood vessel compressing the 8th cranial nerve in the CPA (cerebellopontine angle) or the IAC (internal auditory canal). However, care must be taken in interpreting these scans, as up to 1/3 of normal individuals will have these findings as well. Balance testing (ENG, VEMP), and hearing testing (ABR, audiometry) may show subtle abnormalities. Treatment is usually medical, with agents that are thought to calm irritable nerves, such as oxcarbazepine or carbamazepine. In recalcitrant cases, microsurgery can be considered, with separation of the 8th nerve (the balance nerve) from the offending blood vessel.