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Sunday, September 24, 2023
Dr. Brown: Big strokes and what to do about them
Dr. William Brown. File Photo

Ischemic strokes, those caused by an obstruction in a feeding artery, are more common than hemorrhagic strokes.

Small ones, the result of obstructions in small arteries or arterioles, are common enough and most often related to hypertension. Many are asymptomatic or cause minor symptoms and perhaps, neurological findings.

That was the case with my sister. Her CT scan revealed six so-called lacunes in the base of her brain, only one of which was associated with a loss of balance for a few days. The cumulative effect of many such “small strokes,” however, may be cognitive decline. 

Larger, sometimes massive ischemic strokes are another matter.

For example, should the middle cerebral artery at the base of the brain become blocked by a thrombus or embolus, the clinical outcome can be devastating. This can mean severe weakness on the opposite side, and if the speech area is affected, loss or severe impairment of speech is common. 

Following the obstruction of a large artery like the middle cerebral artery, there are two regions of the brain. For regions where the obstructed artery is the sole source of blood, the affected region dies – some say within minutes.

Recent experimental studies of pig brains suggest the time interval before the death of nerve cells may be much longer – several hours at least, provided the circulation is re-established within four hours in the pig brains. 

Outside the “dead” core is a wider region in the brain where the blood supply is reduced downstream from the blocked arterial branch, but not entirely so. A lifeline of arterial blood may reach the threatened region from neighbouring regions of the brain if supplied by unobstructed arteries.

The threatened region of the brain is often referred to as a “brain at risk.” Nothing can be done about the “dead” region: management is therefore directed toward salvaging the brain which is at risk. 

For some patients, thrombolytic therapy works but with clots the size of the proximal middle cerebral artery, lysis alone isn’t usually enough to break up the obstructing clot.

That’s where embolectomy comes in – plucking the clot out using a catheter threaded up from one of the distal forearm arteries to the obstructed middle cerebral artery. It works well in most instances. 

Doing an embolectomy is not a one-man or woman show: it requires a team on call in a major medical centre with the expertise to do the job. For us in the Niagara region, that means visiting the Hamilton General Hospital an hour away.

The initial assessment is done in this region by the stroke unit at the Niagara Falls hospital and the patient is transferred as needed.

Often the presence of an embolus or clot in the middle cerebral artery can be spotted in a CT scan which is urgently carried out as part of the stroke protocol as is an initial trial of thrombolytic therapy.

Clinical trials in Japan, China and the West recently compared patients who received an embolectomy following a major stroke caused by a clot or embolus obstructing the middle cerebral artery, versus those who did not receive an embolectomy.

The protocols were very similar, as were the results, which an editorial published in the New England Journal of Medicine summarized: Clinical outcomes were better with embolectomy than thrombolytic therapy for patients. 

However, these are large strokes, and many patients have moderate to severe disabilities with or without embolectomy: That’s what bothers me.

I’m not sure I want to be around with such severe disabilities as many of these patients have, regardless of the statistical data showing better outcomes following embolectomy.

It’s an area where spouses and families need to have the best information their physicians can provide about risks and expected real-world outcomes for their spouse, partner or parent.

It’s not a conversation that can be held with some patients should their understanding be very impaired.

These days, high-tech medicine has become common, but sometimes the patient and family don’t understand what the implications are for this or that treatment and what realistic outcomes might look like.

The latter isn’t in the MRI – it’s measured by what patients can and cannot do. 

Try to resist the temptation to use Google as a surrogate source. Excellent information is available online from the Mayo Clinic, Harvard-affiliated hospitals, the National Institutes of Health, and other trusted sites.

However, they are no substitute for talking to the health care professionals in charge of your care or others.  

Normally, pictures are worth many words, but there’s no way to do that with such a brief article. In the fall, I hope to cover this topic and selected others in health care as a way of broadening and deepening the conversation.

Dr. William Brown is a professor of neurology at McMaster University and co-founder of the InfoHealth series at the Niagara-on-the-Lake Public Library.

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