Things are looking up in regard to Covid and I heard an interesting theory that, rather than getting more virulent with successive Covid mutations, the virus needs the infected individual to survive, otherwise it has nowhere to go! This may be the case with the Delta to Omicron mutation. An attractive theory; I hope it is true.
Before Christmas I promised that I would talk about some common illnesses, with some take-home messages that I have picked up over the years, and some exciting new developments. I talked about chest pain in December and the HEART score.
This month I want to talk about stroke. We all probably appreciate what this is and the common presentations. The campaign to highlight FAST assessment – that is abnormal one-sided Facial weakness, an Arm weakness, a Speech problem and the need for Timely intervention is well-known but in my experience the Fast bit is not always appreciated.
I will explain. There are three main arteries supplying the brain delivering 750 ml of blood a minute. This is a big percentage of the heart’s output and, for its weight, the brain gets a huge blood supply. Obstruct one of these arteries – usually from a clot in the system coming from the heart beating abnormally in atrial fibrillation for example or hardened arteries in the neck – and a big problem arises.
Depending on which part of the brain is involved and which side of your brain controls speech, a stroke can affect movement, power, speech, vision and balance. Consciousness is not usually lost and you can imagine the distress and shock this causes.
So why the emphasis on time. The maxim is ‘time is brain’ and after a short three hours of the artery being blocked most of the damage is done and sometimes irreversible.
In the hospital we have a stroke team dedicated to rapid diagnosis and treatment. They are alerted to a FAST positive patient en route and everything is ready to go. Time zero is when the stroke occurred, this has to be accurate. A quick assessment, blood pressure, pulse, blood sugar, ECG and neurological examination is done and the patient quickly taken to CT usually within minutes.
The scan is reviewed by several doctors, usually an expert radiologist, and we have to exclude a bleed into the brain causing the stroke. A bleed is much less common than a clot, but so important to identify, as clot-busting treatment (thrombolysis) will be given and this would be a disaster if the patient has had a bleed causing the stroke. Once back in ED, a full assessment of the severity of the stroke is done and an agreed score reached. Stroke mimics such as migraine, low blood sugar, sepsis , faints and epilepsy for example, are carefully looked for. If the patient is improving rapidly thrombolysis is withheld.
All being well and once the Consultant is happy to sanction thrombolysis, we go ahead and very carefully monitor the patient over the next few days. To see all the symptoms of a stroke resolve is so gratifying.
Three hours is so short a time and while we might try thrombolysis treatment in special cases, sometimes up to 4.5 hours, the results are not so good.
However, we have another trick up our sleeves. This is thrombectomy, i.e removing the clot from the blocked artery. This is really clever stuff and can be used after thrombolysis to optimise recovery. This can be done up to 24 hours after the stroke impacted. A catheter is fed along the blocked artery on the brain and the clot sucked out. Amazing stuff!
So have I now contradicted myself? Is it three hours, 4.5 hours, or 24 hours, to act after a stroke ?
The earlier we act, the better the outcome. TIME again. However, we know that after a stroke, even with no thrombolysis or thrombectomy, the brain can heal and symptoms improve. The damaged area of the brain is like a fried egg. The yolk is dead brain, but the white, the so-called stroke penumbra, is capable of drawing in blood supply from other parts of the brain like the surrounding meninges and improvement can occur.
Thrombectomy gives the stroke penumbra the best chance of getting blood back quickly and clinical improvement, once the clot busting window has passed.
Just a few words about Transient Ischaemic Attacks – TIAs. This, as the name implies, is a short-lived mini-stroke. Usually this lasts less than one hour when a clot has temporarily blocked an artery to the brain but happily moves on. All good? No! Again, the clock is ticking – a cause for the blockage is looked for, ECG done, carotid arteries to the brain scanned, and a MRI, not a CT done, as this is more accurate than a CT. This is another medical emergency and symptoms are not ignored or dismissed. The next time that artery blocks it may not move on and a ‘full blown’ stroke could develop.
Take home message: Sudden onset of a speech, power, eyesight deficit – set your clock and get to the hospital asap. Yes, and please bring all your tablets.