Mr Nigam ENT Treatments - Vestibular Neuronitis and Labyrinthitis
Vestibular neuronitis causes dizziness due to an viral infection of the vestibular nerve. The vestibular nerve carries information from the inner ear about head movement. When one of the two vestibular nerves is infected, there is an imbalance between the two sides, and vertigo appear. Hearing is unaffected.
Labyrinthitis is a similar syndrome to vestibular neuritis, but with the addition of hearing symptoms (sensory type hearing loss or tinnitus).
Symptoms
The symptoms of both vestibular neuritis and labyrinthitis typically include dizziness or vertigo, disequilibrium or imbalance, and nausea. Acutely, the dizziness is constant. After a few days, symptoms are often only precipitated by sudden movements. A sudden turn of the head is the most common "problem" motion. While patients with these disorders can be sensitive to head position, it is generally not related to the side of the head which is down (as in Benign paroxysmal positional vertigo), but rather just whether the patient is lying down or sitting up.
About 5% of all dizziness (and perhaps 15% of all vertigo) is due to vestibular neuritis or labyrinthitis. It occurs in all age groups, but cases are rare in children.
Fortunately, in the great majority of cases (at least 95%) vestibular neuritis it is a one-time experience. Rarely the syndrome is recurrent, coming back year after year. When it is recurrent, the symptom complex often goes under other names. There is often a familial pattern.
In vestibular neuritis, the virus that causes the infection is thought to be usually a member of the herpes family, the same group that causes cold sores in the mouth as well as a variety of other disorders. It is also thought that a similar syndrome, indistinguishable from vestibular neuronitis, can be caused by loss of blood flow to the inner ear. However, present thought is that inflammation, presumably viral, is much more common than loss of blood flow.
In labyrinthitis, it is also thought that generally viruses cause the infection, but rarely labyrinthitis can be the result of a bacterial middle ear infection. In labyrinthitis, hearing may be reduced or distorted in tandem with vertigo. Both vestibular neuronitis and labyrinthitis are rarely painful -- when there is pain it is particularly important to get treatment rapidly as there may be a treatable bacterial infection or herpes infection.
There are several possible locations for the damage to the vestibular system that manifests as vestibular neuronitis. There is good evidence for occasional lesions in the nerve itself, as this can be seen lighting up on MRI scan. It is common to have another dizziness syndrome, BPPV, follow vestibular neuronitis. Presumably this happens because the utricle is damaged (supplied by the superior vestibular nerve), and deposits loose otoconia into the preserved posterior canal.
Investigations
Acutely, in uncomplicated cases, while a thorough examination is necessary, no additional testing is usually required. Certain types of specialists, namely otologists, neurotologist, and otoneurologists, are especially good at making these diagnoses and seeing one of these doctors early on may make it possible to avoid unnecessary testing.
In large part, the process involves ascertaining that the entire situation can be explained by a lesion in one or the other vestibular nerve. It is not possible on clinical examination to be absolutely certain that the picture of vestibular neuritis is not actually caused by a brainstem or cerebellar stroke, so mistakes are possible. Nevertheless, this happens so rarely that it is not necessary to perform magnetic resonance imaging (MRI) scans or the like very often.
Signs of vestibular neuronitis include spontaneous nystagmus (involuntary movement of the eyes), and unsteadiness. However, if symptoms persist beyond one month, reoccur periodically, or evolve with time (see following), testing may be proposed. In this situation, nearly all patients will be asked to undergo an audiogram and sometimes Electronystagmography (ENG).
An audiogram is a hearing test needed to distinguish between vestibular neuronitis and other possible diagnoses such as Menieres’ disease and Migraine. The ENG test is essential to document the characteristic reduced responses to motion of one ear. An MRI scan will be performed if there is any reasonable possibility of a stroke or brain tumour.
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