Background

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Both of the diseases cause acute vestibular failure.This failure is characterised by a rapid onset of vertigo which may be very severe and associated with nausea, vomiting, pallor, sweatiness and diarrhoea (vegetative symptoms).

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Initially, the patient will find it difficult to get out of bed or move at all, as this will provoke the symptoms. Hence, they tend to want to lie still. This phase of the condition lasts for one to two days. After this they are able to move gently and sit in bed but any quick movements will provoke further vertigo and vegetative symptoms.

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After a few days they are able to stand and the following few weeks will see a gradual return to normal function without symptoms, even on quick movements.

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This process of recovery is called 'vestibular compensation' and is achieved by the brain by adjusting vestibular activity within the vestibular nuclei, using other senses, and a number of other neural activities. Compensation is the norm, however, there are certain circumstances where it fails to be completed and the patient is left with residual symptoms. Elderly patients, patients on drugs or with other diseases that affect mobility may not ever make a full recovery and even patients who appear to have made a complete recovery may still experience symptoms at a later date if they become ill, start medication or become over fatigued.

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Note: the vertigo of labyrinthitis and vestibular neuritis lasts for days or weeks. This is in distinction to Ménière's vertigo that lasts hours or a day, and that of BPPV which lasts seconds.

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What is the difference between these two diseases? Labyrinthitis is a disease of the whole labyrinth. Thus, since the labyrinth contains the neuroepithelia of hearing as well as balance, the patient suffers balance and hearing symptoms: vertigo, deafness and tinnitus.

 

Vestibular neuritis is a disease of the vestibular nerve and, therefore, only causes vertigo.

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Pathophysiology

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You should review the section on vestibular physiology before considering the pathophysiology of these diseases. In particular you should note the section that details the genesis of nystagmus and the sensation of spinning.

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The cause of vestibular neuritis is most likely to be viral and possibly of the Herpes family. However, some may be caused by vascular occlusion - recall that the inner ear is supplied by end arteries and that there is no collateral flow. Whatever the cause, it results in a reduction of neural activity in the vestibular nerves on one side and this is what causes the nystagmus and sense of vertigo. The condition is painless and there is no cochlear upset.

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Labyrinthitis is also most likely viral in origin although occasionally bacteria can be the cause (for example when a cholesteatoma has eroded into the inner ear or when an acute otitis media has spread inwards). The hearing loss associated with labyrinthitis is permanent and tinnitus often follows but the vertigo will eventually settle.

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Clinical Examination

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Patients with acute vestibular failure as in labyrinthitis and vestibular neuritis are often pale and sweaty and are reluctant to move for fear of worsening their symptoms of nausea and vomiting. They will have nystagmus in addition. This is almost always towards the opposite ear.

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Examination early on will reveal this uni-directional nystagmus in all directions of gaze. Later, as compensation starts to occur, the nystagmus will only be seen when the patient looks in the direction of the fast phase of the nystagmus. If there is associated hearing loss tuning fork tests will suggest that this is of a sensorineural type.

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In addition to this uni-directional nystagmus the patient will show abnormality on head thrust testing.

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Note that the patient will not be suffering with signs or symptoms of posterior fossa disease: dysarthria, diplopia, facial weakness, dysphagia, loss of vision, facial or limb paraesthesia, limb weakness, etc. These posterior fossa symptoms and their associated signs point to neurological disease such as a circulatory disturbance and the patient will require emergency brain imaging. Follow this link to find out more about differentiating vestibular neuritis from stroke.

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Examination of the ear canal and drum will be normal in all cases unless a middle ear infection or cholesteatoma is the culprit.

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Management

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Acute management is directed at easing nausea and vomiting. This is done by giving an antiemetic such as prochlorperazine, and resting the patient. Hydration is important.

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Once the acute phase is over, and the patient has begun to mobilise  prochlorperazine must be stopped so that full central compensation can occur. The patient is encouraged to gently increase their activities until they return to normal. A hearing aid may be required if labyrinthitis was the cause. Occasionally, where the patient remains disturbed by imbalance, a vestibular rehabilitation program may be offered.

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NB. If there is labyrinthitis in the presence of a cholesteatoma or acute middle ear infection the patient should be hospitalised and considered for emergency surgery to remove disease and prevent septic meningitis. Thus examination of the eardrum is mandatory.

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Management is nearly always at home by Primary Care teams although patients who cannot remain hydrated because of vomiting should be managed in hospital at the moment (unless there is an ambulatory team who can oversee fluid replacement in the home).

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Patients also need:

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1. Advice on rehabilitation in the short and long term

2. Review of progress against mobility goals

3. Prescription of physiotherapy if they are not healing well enough

4. Advice on the home environment, especially if long term imbalance ensues

5. Referral for hearing devices and/or tinnitus advice

6. Diagnosis and management of BPPV if it arises

7. Education and motivation to mobilise and improve