Evaluation of acute stroke
As with all acute, life-threatening conditions it’s important to assess the stability by ABCDE first. All patients with stroke should be admitted to a stroke unit.
The most important and first diagnostic test is native CT. Ischaemia is usually not visible on native CT in the first 6 hours, but intracranial haemorrhage is visible much earlier. Therefore, the goal of native CT is to rule out haemorrhagic stroke. In a patient with stroke symptoms and negative CT, ischaemic stroke is presumed. In some cases, the “hyperdense artery” sign can be seen, which is due to a thrombus in the middle cerebral artery. MRI with DWI sequence is an alternative to native CT.
ECG and labs are important but should not delay the native CT.
The ASPECTS score can be used to score early ischaemic changes on native CT in ischaemic stroke. A score of 10 is a normal native CT, while a score of 0 means that the entire MCA territory is ischaemic.
Vascular imaging is performed after the initial native CT. Its purpose is to learn more about the type of stroke, and how good the collateral blood supply is. Vascular imaging can detect a large artery occlusion, which is an indication for thrombectomy. It can also evaluate whether there is carotid atherosclerosis present. Vascular imaging is usually carotid ultrasound and either CT or MR angiography.
If there is a large artery occlusion, and the 6 hour time window for thrombectomy has passed, we may perform perfusion imaging to evaluate whether the penumbra (the brain area which is potentially salvageable by revascularization) is large enough that late thrombectomy is still beneficial. This is also used in case of “wake-up” stroke, when the patient wakes up from sleep with stroke symptoms and doesn’t know when the onset was. Perfusion imaging is usually MRI with DWI and PWI or CT perfusion.
If embolic ischaemic stroke is suspected, cardiac investigation is necessary, and includes transthoracic or transoesophageal echo, and Holter ECG. These can detect PFO, paroxysmal AF, endocarditis, etc.
Treatment of acute stroke
IV thrombolysis with an rtPA like alteplase is the best treatment for ischaemic stroke. It’s indicated for everyone with ischaemic stroke in which it can be performed within 4,5 hours of symptom onset. The sooner it’s initiated, the better. It can only be performed if haemorrhagic stroke has been ruled out. There are some contraindications, like recent bleeding or surgery, or the patient taking anticoagulants. Imaging should be performed 24 hours after thrombolysis to make sure that no haemorrhage occurred as a complication.
Mechanical thrombectomy is indicated if there’s a large artery occlusion visible on vascular imaging. In large artery strokes, thrombolysis is less effective and so thrombectomy is used. Thrombectomy must be performed within 6 hours of symptom onset, and if they present within 4,5 hours then it should be combined with thrombolysis for best results. If perfusion imaging show a large penumbra, thrombectomy can be performed up to 24 hours after onset.
Aspirin is indicated for all cases of ischaemic stroke, but the timing of it depends on whether thrombolysis is performed. If the patient is treated with thrombolysis, aspirin is given after the 24-hour post-thrombolysis imaging has excluded haemorrhage. If the patient does not receive thrombolysis, aspirin is given immediately.
If there is a malignant middle cerebral artery infarction, a decompressive hemicranectomy can be performed. This is lifesaving but has high risk of disability.
Supportive treatment is also important. Blood pressure management, blood glucose management, and fluid replacement are necessary.
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