Vestibular neuronitis

Vestibular neuronitis, also called Vestibular neuritis, can be a paroxysmal, single attack of vertigo, a series of attacks, or a persistent condition that diminishes over three to six weeks. It is a type of unilateral vestibular dysfunction and may be associated with nausea, vomiting, and previous upper respiratory tract infections. It generally has no auditory symptoms, unlike labyrinthitis. Vestibular neuronitis may also be associated with eye nystagmus. The cause is not clearly understood. It appears to be caused by an imbalance of neuronal input between the left and right inner ears.^[1]

Signs and symptoms

The main symptom of vestibular neuronitis is vertigo, which appears suddenly, often with nausea and vomiting. This can be made worse by head movement. Vertigo usually lasts for several days or weeks. In rare cases it can take months to go away entirely. Vestibular neuronitis does not lead to loss of hearing.^[2] A common indication is horizontal nystagmus with the fast beat towards the healthy ear.

Causes

Some patients will report having an upper respiratory infection (common cold) or a flu prior to the onset of the symptoms of vestibular neuronitis, others will have no viral symptoms prior to the vertigo attack.

Some cases of vestibular neuronitis are thought to be caused by an infection of the vestibular ganglion by the Herpes Simplex type 1 virus.^[3] However, the cause of this condition is not fully understood, and in fact many different viruses may be capable of infecting the vestibular nerve.

Acute localized ischemia of these structures also may be an important cause. Especially in children, vestibular neuritis may be preceded by symptoms of a common cold. However, the causative mechanism remains uncertain.^[4]

Diagnosis

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 symptoms are 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 MRI scans or the like very often. Signs of vestibular neuritis include spontaneous nystagmus and unsteadiness. One may notice that vision is disturbed or jumpy on looking to a particular side. This usually means that the opposite ear is affected – it is called Alexander's law and is due to asymmetric gaze evoked nystagmus. Occasionally other ocular disturbances will occur such as vertical double vision – skew deviation. However if symptoms persist beyond one month, reoccur periodically, or evolve with time, testing may be proposed. In this situation, nearly all patients will be asked to undergo an audiogram and an electronystagmography (ENG). An audiogram is a hearing test needed to distinguish between vestibular neuritis and other possible diagnoses such as Ménière's disease and migraine. The ENG test is essential to document the characteristic reduced responses to motion of one ear. In severe cases, vestibular neuritis can become a chronic health problem that may lead to damage of the vestibular nerve(s), which can subsequently result in complications relating to balance and equilibrium which may persist for months or more. If symptoms do not improve, Vestibular Rehabilitation Therapy (V.R.T.) should be used, which is a form of physical therapy that helps dizziness and balance disorders. It is highly effective in alleviating the often debilitating attacks of vertigo and constant dizziness suffered by those with vestibular neuritis as well as other inner ear disorders and diseases.^[5]

Treatment

The treatment for vestibular neuronitis depends on the etiology of the dysfunction. However, symptoms of vertigo can be treated in the same way as other vestibular dysfunctions, such as labyrinthitis, with vestibular rehabilitation.^[6]

Physical therapy

Although treatments will differ from patient to patient due to the variability of the severity of the condition, typical treatments prescribed by physical therapists include combinations of head and eye movements, postural changes, and walking exercises. Specifically, exercises that may be prescribed include keeping eyes fixated on a specific target while moving the head, moving the head right to left at two targets at a significant distance apart, walking while keeping eyes fixated on a specific target, and walking while keeping eyes fixated on a specific target while also turning the head in different directions.^[7] The main function behind repeating a combination of head and eye movements, postural changes and walking is that through this repetition, compensatory changes for the dysfunctions arising from peripheral vestibular structures may be promoted in the central vestibular system (brainstem and cerebellum).^[7]

Prognosis

In most cases, the condition tends to be self-limiting. In fact, in 95% or greater of these patients, vestibular neuritis is a one-time experience. Most patients tend to fully recover. ^[8]

References

External links