Giddiness

Published on 10/04/2015 by admin

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Last modified 10/04/2015

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Giddiness

Giddiness or dizziness are terms used by patients to describe a wide variety of sensations. It is crucial to obtain a precise understanding of the patient’s presenting complaint in order for clinical evaluation to proceed along appropriate lines. Table 1 summarizes the symptoms commonly described as ‘giddiness’.

Table 1 Symptoms commonly described as giddiness

Symptom Clinical interpretation Comment
Feeling of relative movement (usually spinning) of self and environment Vertigo Peripheral or central vestibular disturbance
Feeling of lightheadedness and impending faintness Presyncope See page 44
Feeling of altered awareness and impaired consciousness Altered consciousness Consider complex partial seizures, absence attacks
Unsteadiness with a clear head Ataxia Cerebellar or proprioceptive

Vertigo

Vertigo is an incorrect perception of relative motion between the individual and the environment. The sensation may be of rotation (semicircular canal dysfunction) or an undulation like being on the deck of a ship (otolith dysfunction) and it may be in any direction. The patient may feel that they or their surroundings are moving. This usually causes postural instability and the patient has to sit or lie down. It is the sensation we normally feel on getting off a playground roundabout. Vertigo causes nausea and sometimes vomiting and there may be associated fear, sweating and pallor. Vertigo is due to a mismatch between sensory inputs involved in maintaining posture. These are the visual, proprioceptive and vestibular systems. In practice, vertigo is usually due to dysfunction of the peripheral vestibular apparatus or its central pathways.

Causes

Seventy per cent of vertigo is caused by four syndromes: benign paroxysmal positioning vertigo (BPPV), vestibular neuritis, Ménière’s disease and phobic vertigo. These can be diagnosed clinically, with minimal investigation. If not falling into one of these categories, then the key anatomical differentiation is between peripheral vestibular dysfunction arising from the vestibular structures in the ear and lesions affecting central vestibular connections within the brain stem.

Clinical assessment

Key features in the clinical assessment are as follows:

image Timing: is the vertigo intermittent or sustained and what is the duration of intermittent episodes?
image Head movement: is vertigo triggered by certain head positions? This usually signifies a peripheral lesion, most commonly BPPV.
image Auditory dysfunction: is there deafness or tinnitus? This points to a disturbance of the labyrinth or vestibulocochlear nerve. Once in the brain stem, auditory and vestibular function are separate.
image Medication: anticonvulsant toxicity causes vertigo and aminoglycosides cause irreversible vestibular damage.
image Eye movements: nystagmus without vertigo generally points to a CNS cause.
image Signs of CNS involvement (ataxia, dysarthria, sensory and motor signs in the limbs) point to an intracranial cause.

Types

Intermittent vertigo

Positional
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