Mechanical thrombectomy can limit disability from stroke even upto 24 hours in carefully selected patients
Majority of stroke (85%) occurs when blood stops flowing to a part of the brain due to a clot or thrombus, usually referred to as ischaemic stroke. This interruption in blood flow leads to damage to the surrounding brain cells. This sudden obstruction in blood flow due to the clot or thrombus can be reversed by administration of a ‘clot busting’ drug, also called thrombolysis in the initial 4.5 hours or mechanically removing the clot (endovascular therapy or mechanical thrombectomy) in the initial 6 hours. While mechanical thrombectomy is most effective when performed within six hours of symptom onset, it can also reduce functional deficits in patients up to 24 hours after stroke symptoms start. Recent landmark trials (DAWN trial, DEFUSE 3 trial) have shown that mechanical thrombectomy can limit disability from stroke even upto 24 hours in carefully selected patients.
Medibulletin looks at mechanical thrombectomy in this explainer.
What is mechanical thrombectomy ?
Mechanical thrombectomy is a novel interventional modality developed for the management of acute ischaemic stroke. Mechanical thrombectomy includes passage of a catheter/device through our groin to the brain, visualizing the block in the brain and taking out the clot through the device. In general we can consider it to be similar to clearing a blocked drain at our home. Mechanical thrombectomy is meant to clear only the blocked blood vessel which is responsible for the stroke.
Patients in whom a large blood vessel is blocked like the internal carotid artery (ICA) and first two branches of middle cerebral artery  (M1,M2 segment) will be the candidate who can undergo this procedure
Which stroke patients will benefit from mechanical thrombectomy ?
Patients who have developed sudden onset ischaemic stroke within 6 hours from the beginning of the symptoms are the fair candidates. Recent landmark trials, DAWN and DEFUSE 3, have prolonged the window period up to 24 hours in selected cases. Patients in whom a large blood vessel is blocked like the internal carotid artery (ICA) and first two branches of middle cerebral artery  (M1,M2 segment) will be the candidate who can undergo this procedure. Sometimes, patients who cannot be administered IV tPA (Clot busting injection) and have major blood vessel occlusion, can also be benefit from this procedure. In no way, IV tPA can be a substitute for mechanical thrombectomy and vice-versa, although both modalities can be used together in some cases which will be dependent at the discretion of the treating neurologist. Other radiological requirements according to the Society of NeuroInterventional Surgery (SNIS) recommendations have been recently published in the BMJ.
How safe is the procedure?
It is a relatively safe procedure in experienced hands and at a center which has experience of performing a high number of such procedures. Complications of mechanical thrombectomy include spasm in blood vessel, perforation of arteries, device misplacement, bleeding into the brain or subarachnoid space, passage of a piece of the clot to a new vessel territory. Local problems like blood clotting, blood vessel or nerve injury in the groin are also known. Although these complications seem a bit dangerous, but their incidence is less than 10%. Mechanical thrombectomy is a procedure that can drastically change the outcome in a stroke patient. Mechanical thrombectomy can dramatically reverse the weakness of arms or legs to near normal power, and also reverse the difficulty in speaking or loss of speech to normal speech. It can be a game changer in neurological improvement of stroke patient but decision regarding the same depends on careful risk benefit analysis.
