Tuesday, October 21, 2014

Central Vestibular Disorders

Definition

Deficits in vestibular function typically cause dizziness, loss of balance, and diminished functional independence and reflect a disturbance of the central vestibular pathways in the brain.

Causes

Central nervous system causes of vertigo (central vestibular disorders) include brain stem vascular disease, arteriovenous malformations, acoustic neuromas and tumors of the brain stem and cerebellum, multiple sclerosis, and vertebrobasilar migraine.

Symptoms

Vertigo is the cardinal symptom of vestibular disease. It is either a sensation of motion where there is no motion, or an exaggerated sense of motion in response to a given bodily movement.

Thus, vertigo is not just "spinning" but may present, for example, as a sense of tumbling, of falling backward or forward, or of the ground rolling beneath one's feet. It should be distinguished from imbalance, lightheadedness, and syncope, all of which are usually nonvestibular in origin.

The vertigo arising from central lesions tends to be more chronic and debilitating than that resulting from peripheral vestibulopathy. Vertigo of central origin often becomes unremitting and disabling. There may be nausea and vomiting.

There are commonly other signs of brain stem dysfunction (e.g., cranial nerve palsies; motor, sensory, or cerebellar deficits in the limbs) or of increased intracranial pressure. Nystagmus (jerking motion of the eyes) may also occur.

One characteristic of neural hearing loss is deterioration of speech discrimination out of proportion to the decrease in pure tone thresholds. Another is auditory adaptation, in which a steady tone appears to the listener to decay and eventually disappear.

Diagnosis

Diagnosis is based on the medical history, physical examination, hearing tests, and a radiological study (head CT scan or head MRI).

Treatment

While the underlying cause should be investigated and treated, symptomatic treatment is useful in the vertiginous patient to lessen the abnormal sensation and to alleviate vegetative symptoms such as nausea and vomiting. The most common drug classes employed are the antihistamines, anticholinergics, and sedative-hypnotics.

Various procedures have been described for the rehabilitation of patients with vestibular deficits. Although there is no uniformly accepted definition of vestibular rehabilitation, these procedures commonly involve repeated head movements to habituate dizziness, positioning maneuvers to prevent the onset of vertigo, exercises to improve eye-head coordination and the fixation of gaze, and balance retraining therapy.

Surgical remedies are used for those who remain substantially disabled despite a trial of medical therapy and exercises. Acoustic neuroma is often treated by microsurgical excision or by stereotactic radiotherapy. Vascular compromise may be treated with vasodilators and aspirin as well as treatment for migraines.

Questions

What is the cause of the vertigo?

Is there an underlying medical problem?

How is the central nervous system involved?

What treatment do you recommend?

Will you prescribe medications?

How long will these medications have to be taken?