STROKE

A devastating  situation

Stroke is a medical emergency that requires rapid diagnosis and treatment.  Its hallmark is the abrupt onset of symptoms entailing the loss of neurological function due to interruption of the blood supply to a specific area of the brain. 

These areas of the brain have been extensively mapped by anatomists and neurologists since the late 19th. century, so that  a physical examination of the patient by a doctor can reliably establish the damaged area: lesions  in the territory supplied by the carotid arteries (the anterior circulation)  produce a combination of functional loss: paralysis of one side of the body (hemiparesis), with or without loss of speech, partial loss of vision, loss of sensation of one side of the body, all on the opposite side of the lesion   This apparent contradiction is because the nerves that come down from the brain (and those that take up sensation to the brain) cross over before reaching the spinal cord, so that a lesion on the left side will produce a deficit on the right side of the body, and viceversa.   On the other hand, the interruption of blood flow to the back part of the brain, supplied by the 2 vertebral arteries which join up into one as they enter the skull, produces a variable combination of sensory and motor defects, either on one or on both sides of the body.  

These findings on examination by the physician, today are complemented by a Computed Axial Tomogram (CAT or CT scan), by a Magnetic Resonance study, or its variant to identify the arteries (angioresonance), by heart and neck artery sonograms (echograms) when necessary, besides the routine studies done on all patients.

The two main causes of stroke are interruption of blood flow, also called ischemia, and hemorrhage inside or outside the brain.  

According to how long the ischemic interruption lasts, strokes are called Transient Ischemic Attack (TIA) if they last less than 24 hours, and Reversable Ischemic Neurological Deficit (RIND) if they last less than a week. If the period is longer, we are facing a completed stroke.

A 20% of these short or definitive conditions are due to embolism from clots originating in the heart (such as in a common rhythm disturbance called atrial fibrillation), or in small pieces of the atherosclerotic plaques in the neck arteries dislodging and floating up to the brain, and impacting and occluding a small artery. If they are sufficiently small, the body can dissolve them, and the patient recovers spontaneously, but must have all the necessary tests and treatments performed to avoid it happening again in a more disastrous fashion.

Other than recent blows to the skull, there are three major causes underlying the cause of spontaneous hemorrhage in the brain. A common cause is the rupture of a “berry” aneurysm of a cerebral artery, which causes a very severe headache, progressing rapidly to neurological deficits due to pressure of the blood on the brain inside the bony skull vault. It is one of the leading causes of sudden death in young people, and is due to a malformation and weakness in an artery determining it to balloon, stretching and thinning its wall.  Another cause is the lesion in small arteries of the interior of the brain in people with chronic high blood pressure, causing hemorrhage inside the brain (a very strong reason for keeping the blood pressure within normal figures to avoid this).  A third common cause occurs in the very elderly, when material called amyloid in the small arteries weakens them, and facilitate their rupture and subsequent bleeding. 

There are conditions that are associated with a higher incidence of stroke: cardiac rhythm disturbances and hypertension have been mentioned. Diabetes, the use of anticoagulants, diseases which affect the small arteries, smoking, an anemia called sickle cell anemia, the illicit use of intravenous drugs, cocaine in all its forms, and occasionally contraceptive drugs.

Many people are now taking anticoagulant medicines for the treatment of different illnesses, and for the prevention of others in which clots have been formed either in the heart or within the arteries. Though the possibility of having a hemorrhagic complication is increased, if one controls his or her clotting times, and adjusts the dose of the anticoagulant accordingly once a month the risk is very small. On the other hand, anybody on anticoagulants who has a blow to the head, however light, should consult the physician shortly, to make sure that nothing has happened inside the skull.

Most people know that if a person has chest pain it could mean a heart attack (or myocardial infarction), and if he or she is assisted in the first 6 hours, doctors can dissolve the clot or remove it, before the heart muscle is definitely damaged, recovering completely. The same goes for stroke, with the difference that the time frame for trying to revitalize the brain is a little shorter, ideally less than 3 hours.  For this reason, some medical institutions such as the British Hospital, are equipped for it, and have doctors specially trained on call 24 hours a day in their Stroke Unit, led by Prof. Dr. M.M. Fernández Pardal, to try and revert this devastating consequence of cerebrovascular disease.  This is done with early intravenous drip of fibrinolytic drugs, which actively dissolve clots. It is very powerful medication, and has a list of contraindications to its use which precludes some stroke victims from receiving it, as the risk of severe hemorrhage is present. The main job of this team of doctors is to identify as fast as possible who can and who cannot receive these drugs. Those that can, in a few hours, magically it would seem, recover completely from their paralysis.  This determines a complete return to normal life, avoiding prolonged hospital admission and rehabilitation, plus some form of permanent neurological function.  The impact on medical costs is astronomical. 

So the message is: avoid the mentioned risk factors, treat those that are identified long term, and rush to a good medical centre as soon as the onset of stroke is suspected.


Author:  Dr. John Emery, MD