Transient ischaemic attack (TIA)
A transient ischaemic attack (TIA) or “mini stroke “is a short lasting reversible episode of neurological symptoms due to the reduction in blood supply to the nervous system. It resolves within 24 hours. If symptoms persist for more than 24 hours it is referred to as a stroke or cerebrovascular accident (CVA).
A transient ischaemic attack is an important cause of vertigo and dizziness and often lead to stroke that might be irreversible and fatal. It is therefore important to diagnose transient ischaemic attacks early on, conduct investigations and implement preventative measures to avoid stroke.
Occurring more often in older patients, some risk factors have been identified. These include hypertension, smoking, diabetes, hypercholesterolaemia, obesity, family history and heart problems. There are mainly 4 arteries that supply blood to the brain. The 2 carotid arteries in the front at the side of the neck mainly supply the cerebrum of the brain. The two vertebral arteries at the back of the neck supply the brainstem, cerebellum and inner ear. The symptoms a patient may experience depend on the artery involved. When the blood supply in the vertebral arteries is disrupted the lack of oxygen causes brainstem ischaemia. Disruption may be due to a clot, a spasm or rarely a bleed.
Brainstem ischaemia may cause vertigo and dizziness. It is usually accompanied by other neurological symptoms such as double vision (diplopia), speech impairment, slurring of speech (dysarthria), difficulty swallowing (dysphagia), numbness and poor coordination. Ataxia (broad base gait) may be present. Wallenberg syndrome is a common ischaemic syndrome if the side of the lower brainstem (medulla) is involved.
In rare cases only the blood supply to the inner ear may be disrupted. Such patients may present with vertigo and or hearing loss as the only symptoms. Isolated spells of vertigo and dizziness usually lasts seconds to minutes. It may be difficult to diagnose. In the emergency setting a transient ischaemic attack should be considered as a possible cause for acute vertigo.