Dizziness

A sensation of unsteadiness and light-headedness. It may be a mild, brief symptom that occurs by itself, or it may be part of a more severe, prolonged attack of vertigo with nausea, vomiting, sweating, or fainting. Most attacks are harmless and are caused by a fall in the pressure of blood to the brain. This can occur when getting up quickly from a sitting or lying position (called postural hypotension). Similar symptoms may result from a transient ischaemic attack, in which there is temporary, partial blockage in the arteries that supply the brain. Other causes include tiredness, stress, fever, anaemia, heart block, hypoglycaemia, and subdural haemorrhage. Dizziness as part of vertigo is usually due to a disorder of the inner ear, the acoustic nerve, or the brainstem. The principal disorders of the inner ear that can cause dizziness and vertigo are labyrinthitis and Ménière’s disease. Disorders of the acoustic nerve, such as acoustic neuroma, are rare causes of dizziness and vertigo. Brainstem disorders which can cause dizziness and vertigo include a type of migraine, brain tumours, and vertebrobasilar insufficiency. Brief episodes of mild dizziness usually clear up after taking a few deep breaths or after resting for a short time. Severe, prolonged, or recurrent dizziness should be investigated by a doctor. Treatment depends on the underlying cause.