Did you know that you can suffer a stroke in your sleep? This is known as a wake-up stroke and it was discussed at the Irish Association of Emergency Medicine (IAEM)’s annual conference in Dublin recently.

Dr Fernanda Bellolio, from the Department of Emergency Medicine and Health Sciences Research at the world-famous Mayo Clinic, in the US was in Dublin recently speaking about the phenomenon of wake-up stroke or a stroke that occurs in your sleep.

According to Dr Bellolio, when a patient is brought in with a stroke the first question doctors ask of the ambulance staff or the patient is: at what time did the symptoms start?

“But what if no one knows? Or if the patient woke up with stroke symptoms?” she asked. This is known as a ‘wake-up stroke.’

What is wake-up stroke?

Wake-up stroke is a stroke that happens in your sleep. The definition of a wake-up stroke is one where a patient wakes up with stroke symptoms that were not present prior to falling asleep. It is estimated that 20 per cent, or one in five of all strokes are wake-up strokes

What causes wake-up stroke?
Dr Bellolio explained that wake up strokes were influenced by circadian or night time changes in blood clotting, hormone levels and neurological function and like cardiac events, strokes were more common in the morning.

She added that other factors that may be involved in wake-up stroke included: sleep-disordered breathing and uncorrected sleep apnoea that results in frequent episodes of reduced oxygen to the brain. These changes can predispose a person to cardiac ischemia like a heart attack, and arrhythmias like atrial fibrillation, which, Dr Bellolio said could further reduce the blood flow to the brain. This is particularly important in patients with cholesterol plaques in the arteries in the neck that bring blood from the heart to the brain, she added.

Is there any other difference between wake-up stroke and other acute strokes, apart from timing?

No, the symptoms of the stroke are going to be the same, for example difficulty speaking (slurred speech), difficulty moving one side of the body or facial droop. Wake up strokes are also no different to other strokes in terms of severity etc.

What is the treatment for wake-up strokes- does it differ in any way?
Dr Bellolio explained that the treatment for wake-up stroke was a bit different to that for other types of stroke as the clot busting drug called “alteplase” or “tPA” has not been approved for wake-up strokes.

“In wake-up strokes we are not sure the exact time that the symptoms started, and these patients were excluded from all the initial clinical trials. A European study showed that some patients with wake-up stroke can be eligible for thrombectomy (or clot retrieval). This means that in some cases we can use a device to mechanically remove the clot and open the blood flow to the brain, just like how a cardiologist can open the blood flow to the arteries in your heart after a heart attack.”

According to Dr Bellolio, wake -up strokes should be treated like other acute strokes: as an emergency and brain imaging or special X-ray type tests of the brain can help in determining the best treatment.

“We use brain imaging to find patients who may be eligible for treatment. We start with a regular computed tomography (CT) of the head to rule out other causes of the symptoms, like a head bleed or brain tumour. Then we do another x-ray type test called a CT angiogram, [where a CT scanner is used to produce detailed images of blood vessels and tissues in various parts of the body. A dye is usually injected through a small catheter placed in a vein of the arm] that gives contrast to the arteries and looks for patients that might be eligible for thrombectomy. And lastly, we look for brain perfusion, to see if there is an area to the brain where the blood flow has been reduced because of the stroke but not yet completely blocked (infarcted). After this evaluation, a small group of patients with wake-up stroke will be eligible for thrombectomy and will be transferred to Stroke Centres, where they can have the procedure.”

What is the most important message in relation to wake up stroke?

Dr Bellolio said it was vital that patients who awaken with stroke symptoms go immediately to the Emergency Department.

“Ideally they are should be accompanied by a family member who knows which medications the patient is taking and the last time they were seen normal (with no symptoms). The treatment for strokes depends on the time of the symptoms. Patients that present right away have better outcomes compared to those who wait at home,” she advised.

Dr Bellolio addressed the Annual Scientific Meeting of the Irish Association of Emergency Medicine which took place in Dublin on the 18 and 19 October 2018.

The future of wake-up stroke looks positive as new developments and recent studies have provided examples where these types of strokes can be treated more actively.