Investigations

Once a clinical diagnosis of stroke or TIA has been made, additional investigations are used to confirm the diagnosis and to determine the cause of the event, specifically if it is cardiac or carotid in origin.

Routine investigations should include full blood count, electrolytes, erythrocyte sedimentation rate, C-reactive protein, renal function, cholesterol and glucose levels, although direct evidence is lacking for each of these investigations. An electrocardiogram (ECG) should also be conducted routinely to detect atrial fibrillation. If clinical history, imaging and routine investigations do not adequately identify the underlying cause then further investigations may be warranted.

Imaging

To confirm the diagnosis, exclude stroke mimics, and differentiate intracerebral haemorrhage (ICH) from ischaemic stroke, magnetic resonance imaging (MRI) is widely considered the modality of choice for brain imaging. However, routine use of MRI is limited because it takes a longer time compared to computerised tomography (CT), and there is limited availability of MRI scanners in many centres. For the foreseeable future it is likely that CT will remain the most frequently used imaging modality.

Advanced MRI and CT imaging techniques may be used in the hyperacute phase to identify ischaemic brain tissue and tissue that's potentially viable, and thus guide intervention decisions.

Carotid or vascular imaging with duplex Doppler ultrasound, CT angiography, or magnetic resonance angiography help to confirm the initial diagnosis and decide the appropriate intervention pathway.

Cardiac investigations

Echocardiography (ECG) is an important tool for detecting whether the heart is the source of embolism. In patients where the stroke mechanism is uncertain after relevant intracranial or extra-cranial imaging, transthoracic echocardiography (TTE) should be considered.

The timing and urgency of the test depends on the level of suspicion of cardioembolic source. Both TTE and trans-oesophageal echocardiography (TOE) have advantages and disadvantages, and the use of TOE after a normal TTE should be individualised.

Atrial fibrillation (AF) is detected with electrocardiography (ECG). The optimal duration and device for ECG monitoring remain to be determined. ECG monitoring is also used in the early phase of stroke to identify cardiac complications including arrhythmia.

For current research and evidence-based recommendations see our Clinical Guidelines.