Flying on the Brain

In a recent article, I discussed myocardial infarction, a condition that occurs when the blood flow in one or more of the coronary arteries is blocked. A similar situation can occur with the arteries that supply the brain as well. When a portion of the brain is deprived of its blood supply, the person suffers a stroke.

The brain has a complex circulation, the anatomy of which is beyond the scope of this article, but if any of the arteries supplying the brain are cut off, the person will experience some sort of neurologic symptom that will depend on the specific part of the brain that is deprived of oxygen.

There are two major types of stroke – ischemic and hemorrhagic. Ischemic strokes result from an interruption of blood flow to the brain and are subdivided into two types – thrombotic (from a clot that forms in the vessel itself, usually on an atherosclerotic plaque) or embolic, where a clot that forms elsewhere in the body (usually the heart) breaks off and travels to the brain where it plugs an artery thereby causing the brain tissue supplied by that artery to die. Hemorrhagic strokes occur when a vessel in the brain ruptures (breaks) and allows blood to enter into the brain tissue or the area above the brain, between the brain and the skull. In this case, the brain tissue is compressed and little, if any, blood flows past the point of vessel rupture to whatever brain tissue that particular
vessel supplied.

Strokes have been decreasing in frequency over the years, but there are still about 800,000 strokes yearly in the United States. About 35 percent of strokes occur in persons under 65, and they are the fourth most common cause of death in the United States.

When a stroke occurs, the symptoms will vary depending on the part of the brain that is affected. If, for example, the part of the brain that controls movement is deprived of its blood supply, the person will have difficulty moving his extremities on the side opposite of the injured side of the brain. If the speech center of the brain is afflicted, the person will be unable to speak properly and may slur words or otherwise have problems speaking. The most common  symptoms are sudden numbness or weakness, most often involving only one side of the body, trouble speaking,  mental confusion, sudden difficulty seeing, dizziness, loss of balance and headache. If the stroke involves a major vessel that supplies a large part of the brain, it can result in rapid loss of consciousness and death. The potential symptoms are endless and significant incapacitation can occur quite rapidly. Anyone who thinks they might be having a stroke should get to a medical facility immediately; prompt intervention can limit long-term neurologic impairment.

There is also a condition called a TIA, or Transient Ischemic Attack. In this condition, also referred to as a “mini stroke,” there is a temporary interruption of blood flow from spasm, or possibly from a small clot that frees itself. The symptoms are similar to a stroke, but only last for a short period of time. Persons who have had TIAs are at significantly greater risk of a full blown stroke than the population at large.

There are several risk factors that make strokes more likely. These include obesity, smoking, diabetes, sleep apnea, hypertension, high cholesterol levels and a history of heart disease and atrial fibrillation. People taking anticoagulants are at higher risk for hemorrhagic stroke, and that’s why the FAA wants to be certain that anti-coagulated applicants have their medication very well regulated. Note that the risk factors for stroke are similar to the risk factors for a host of other conditions that also can result in loss of a medical certificate. The moral of this is to try to keep yourself in good condition; watch your weight, exercise regularly, don’t smoke and take care of little problems before they become big ones.

Because of the high probability of some degree of incapacitation, the FAA is quite concerned about strokes in pilots and any history of a stroke or TIA is disqualifying for any class of medical certificate.

If you suffer a stroke or TIA, you are effectively grounded and are not eligible for either a medical certificate or special issuance for at least two years. There are some exceptions for TIAs if the cause is recognized and corrected. You will have to submit a complete treatment record detailing the specifics of the stroke and your convalescence, a current and complete neurologic evaluation by a neurologist, a complete cardiovascular evaluation, a Doppler ultrasound of your carotid arteries (the major arteries that supply the brain), a 2D echocardiogram (an ultrasound of the heart to rule out clots in the heart that can embolize to the brain), and finally, a computerized tomographic angiography or Magnetic Resonance angiography of the neck and brain. Those latter tests are simply either a CT scan or MRI in which contrast material is injected so that the arteries and vessels to and in the brain can be visualized.

Even if a person does receive a special issuance after a stroke, he will have to submit to extensive testing with every renewal. Strokes are not part of the AME assisted Special Issuance Program and every renewal will have to be approved by the FAA.

The items discussed in this column are related to experiences by Dr. Seckler in his many years as an AME, and made hypothetical for the article. Any information given is general in nature and does not constitute medical advice.