Dizziness

Published on 23/05/2015 by admin

Last modified 22/04/2025

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Dizziness

Spatial disorientation may be expressed by the patient as dizziness, vertigo or feeling ‘light-headed’. True vertigo is not experienced as a sensation of movement but as tilting or sloping of the environment.

Causes

Episodic

• Ménière’s disease *

• BPPV

• Arrhythmia

• Postural hypotension

• Migraine

• Hyperventilation

• Drugs (antihypertensives, antidepressants)

• Hypoglycaemia

• Recurrent posterior circulation TIAs

• Anxiety

• Seizures (partial)

• Carbon monoxide poisoning (e.g. faulty heating)

Constant

Acute Onset

• Labyrinthitis *

• Acute alcohol or drug intoxication

• Head injuries *

• Vestibular neuronitis

• Posterior circulation CVA

Gradual Onset

• Multiple sclerosis

• Aortic stenosis

• Cerebellopontine angle tumour *

• Ototoxicity – aminoglycosides *

*Indicates causes accompanied by audiological symptoms.

History

General

The causes above are listed according to speed of onset and duration of symptoms. Conditions that are accompanied by additional audiological symptoms, such as tinnitus, are marked with an asterisk.

Precipitating factors

Causes of dizziness that are precipitated by movements of the head include BPPV, labyrinthitis and head injuries. Patients with BPPV complain of short episodes of dizziness accompanying changes in the position of the head. Labyrinthitis may result either as a complication of systemic viral infection or from extension of a cholesteatoma due to chronic suppurative otitis media. A history of trauma is usually obvious. Postural dizziness precipitated by rising from a lying position may be caused by orthostatic hypotension commonly secondary to antihypertensive drugs.

Associated symptoms

Dizziness may be precipitated by arrhythmia and patients may complain of associated palpitations. It may also be experienced with migraine attacks and patients may complain of associated unilateral throbbing headache, nausea, vomiting and photophobia. Ménière’s disease is diagnosed with a history of episodic severe vertigo with continuous tinnitus and hearing loss. Patients with vertebrobasilar insufficiency from cervical spondylosis may complain of dizziness with extension of the neck. With posterior circulation TIAs, sudden onset of dizziness is caused by ischaemia of the lateral brainstem or cerebellum. This may be accompanied by syncope, nausea, vomiting, visual field defects and diplopia. Severe progressive vomiting and ataxia may also result from intracerebellar haemorrhage – a neurosurgical emergency. Patients with anxiety disorders may experience attacks of dizziness, tinnitus and tremor, with or without accompanying hyperventilation. Certainly, hyperventilation alone is sufficient to precipitate dizziness. Vertigo is a prominent feature of multiple sclerosis when demyelination occurs in the brainstem; this may be accompanied by dysarthria and cranial nerve palsies. Young age would favour the diagnosis of demyelination over ischaemia. Tumours of the cerebellopontine angle tend to present gradually, dizziness may be mild and this may be accompanied by numbness and facial paralysis due to trigeminal and facial nerve involvement. There are no precipitating factors for vestibular neuronitis; the dizziness is not associated with nausea or tinnitus.

Drug history

Numerous drugs have ototoxic effects; perhaps the most commonly known are aminoglycosides and frusemide.

Examination

Assessment of nystagmus, hearing and positional testing provide most information when determining the cause of dizziness.

Multidirectional nystagmus results from diffuse cerebellar disease, while unidirectional nystagmus occurs either with ipsilateral cerebellar disease (multiple sclerosis, posterior circulation TIA/CVA) or contralateral vestibular disease (Ménière’s, labyrinthitis, acoustic neuroma). On lateral gaze, nystagmus of the abducting eye with failure of adduction of the opposite eye, is due to internuclear ophthalmoplegia, classically caused by brainstem demyelination.

Hearing is assessed with Rinne’s and Weber’s tests (p. 96). Sensorineural hearing loss may be caused by Ménière’s, acoustic neuroma and drug-induced ototoxicity. Hearing loss accompanied by trigeminal and facial nerve palsy may be due to tumour effects at the cerebellopontine angle.

Specific positional tests, such as the Hallpike test, are performed to assess the integrity of the vestibulo-ocular and labyrinthine pathways. Patients with BPPV usually complain of vertigo and exhibit delayed nystagmus that fatigues on repeated testing.

A complete neurological examination is then undertaken. Homonymous hemianopia can result from posterior circulation infarcts and brainstem lesions such as demyelination, and stroke may give rise to combinations of ipsilateral cranial nerve palsies and motor or sensory deficits of the face. In addition, pale optic discs due to optic atrophy may be seen in multiple sclerosis. Patients with cerebellar disease will exhibit an intention tremor when performing the finger–nose test. In addition to a broad-based ataxic gait, they may also exhibit nystagmus, dysdiadochokinesia and dysarthria.

When a cardiovascular cause is suspected, the pulse is assessed for irregularities of rhythm, which may suggest atrial fibrillation. The blood pressure is measured both lying and standing to screen for postural hypotension, and potential sites for emboli, such as the cardiac valves and the carotid vessels, are auscultated for murmurs and bruits, respectively. Severe aortic stenosis may lead to dizziness.