Carotid Dissections, Stroke and Telestroke

New York Times reporter Andrew Revkin recently wrote an article that did a great job of describing a stroke from a patient’s perspective, as well as discussing some new advances in stroke treatment technology.

The first point his case illustrates is that stroke can occur at all ages, from babies to the elderly. It may be especially difficult for younger and fit patients to understand they are having a stroke. Since it’s an “an old age disease,” it can’t be happening to them. Knowing the warning signs of stroke — sudden onset of weakness or numbness on one side, difficulty in speaking, or sudden vision loss — is therefore important to everyone.

The type of stroke that Revkin had — one due to a dissection or tear in one of two carotid arteries in the neck — is actually one of the more common causes of stroke in a younger person. In a dissection, the inner lining of the blood vessel tears away, creating a flap where a blood clot can form inside the vessel. This in turn can break loose and go to the brain and cause a stroke.

It doesn’t have to be a major trauma that causes this tear. It can occur with regular activity — like running, in Revkin’s case. Other common causes we frequently see in patients at OHSU’s Oregon Stroke Center include neck chiropractor manipulation, extreme yoga neck extension, tilting the head back to get your hair washed, and extreme coughing fits. One of the more interesting cases we’ve seen had dissections in both carotid arteries from working in the local planetarium (looking up at the stars all day). Fortunately, in Revkin’s case — based on what he’s written — the doctors finally arrived at the correct diagnosis (with some assistance from the patient!) and he was placed on the appropriate blood thinning treatment that likely limited his stroke injury.

The good news is that in many cases of carotid dissection, the artery will eventually heal itself and reopen and the risk of a repeat dissection in a patient is very low. I hope this will be the case for him.

Dr. Clark consults via telemedicine console The second point Revkin’s blog article illustrates is the exciting potential of telestroke technology to deliver expert stroke care to patients in an area where a local stroke specialist is not available.

Oregon Health & Science University hospital currently has a nine-hospital “telestroke” network in Oregon where we can evaluate the patient and assist local hospitals around the state. At these “stroke ready” hospitals, patients with an ischemic stroke (no blood flow to the brain due to a blocked artery) can be evaluated and if appropriate given the “clot buster” stroke therapy tPA as quickly as possible under the direction of the telestroke specialist.

For many patients, however, intravenous tPA alone may not be sufficient. In these cases, more advanced “interventional” techniques are required to try to pull out the clot that is causing the stroke. In addition, there are other types of strokes that can be caused by an artery breaking inside the brain (a cerebral hemorrhage) or an artery popping on the surface of the brain (a subarachnoid hemorrhage). For these very critical patients, both specialized neurointerventionalists and cerebrovascular neurosurgeons are required to stop the bleeding using clips or coils. This is where a Comprehensive Stroke Center like OSHU’s is required. For these cases, the telestroke physician can help orchestrate transferring the patient. In addition they can reassure and update the family face to face.

Hopefully, everyone knows how important it is to seek immediate medical attention if you are having symptoms of a stroke. TPA is most effective when given within three hours of a stroke. And the newer clot removing devices (called stent retrievers) are approved for use up to eight hours after known stroke onset. However, there are times where the ability to get to an emergency room in time is beyond the patient’s or family’s control. Examples include if the stroke occurs while someone is asleep or if he or she is found with stroke symptoms and is unable to communicate when it started.

Image of a perfusion scan.

This means that these patients usually arrive too long after being normal to be able to treat them. However, new advances in brain imaging may be changing these strict time limits. Using a special brain CT or MRI perfusion scan allows us to determine how much of the brain is already too badly injured to save (core area) and how much is not getting enough blood but might still be saved if treated (low blood flow area). If the area of low blood flow is larger than the core damaged area, treatment might still help the patient, regardless of how many hours ago the patient was last normal.

Through improved stroke patient education about the need to seek immediate medical care and through telestroke technology and advanced imaging techniques, we hope in the future to have more of our patients to be able to return to writing blog articles!

Wayne Clark, M.D.
Director, Oregon Stroke Center
OHSU Brain Institute