What is Stroke?
A stroke is an interruption of blood supply to any part of the brain due to blockage of blood vessel. There are two types of stroke:
- Ischemic stroke - can be thrombotic or embolic and occurs mostly due to atherosclerosis.
- Haemorrhagic stroke - occurs due to bursting of arteries supplying the brain, mostly due to uncontrolled high blood pressure,
Symptoms of stroke
- Headache – sudden in onset and severe
- Muscle weakness in face, arm or leg (usually on one side only)
- Numbness or tingling on one side of the body
- Difficulty in speech, vision, hearing
- Loss of memory
- Loss of coordination and balance
- Lack of control over bladder/bowel
Medical tests that bring on symptoms of stroke
The following are the medical tess that will bring on symptoms of stroke:
- Carotid artery palpation
- Carotid/coronary angiography and cardiac catheterization
Carotid artery palpation
The carotid artery is the main artery supplying blood to the brain. The carotid sinus (CS) is a pressure sensitive receptor located on this artery, which plays a central role in blood pressure homeostasis. Changes in stretch and pressure within the artery are detected by these receptors and transmitted to the brain.
Carotid artery palpation can be done as part of routine pulse examination or in the diagnosis of aortic stenosis. It requires the artery to be palpated by the person conducting the test. In certain individuals who are hypersensitive to such a palpation may develop an exaggerated response, often resulting in dizziness, loss of consciousness and hypotension, numbness or tingling, thereby mimicking the symptoms of stroke.
Carotid artery palpation can also discharge a pre-existing thrombus in the carotid artery, causing an embolus, resulting in stroke.
Such hyper-responsiveness can be spontaneous or induced. Spontaneous responses are rare, while induced responses due to carotid sinus massage occur more frequently. It is found in 0.5-9% of patients with recurrent syncope. Rates of total mortality, sudden death, myocardial infarction or stroke are unaffected.
Carotid / Coronary Angiography and Cardiac Catheterization
Stroke occurs as a rare adverse effect of certain invasive investigations like coronary/carotid angiography and cardiac catheterization.
Coronary/carotid angiography uses a special dye as contrast material and X-rays to visualize the blood flow through the coronary/carotid arteries. It is done to detect blockage in the arteries in case of atypical chest pain, aortic stenosis, unexplained heart failure or unexplained syncope.
Cardiac catheterization is usually undertaken to identify the extent and severity of coronary artery disease and evaluation of left ventricular function. The risk of stroke following this procedure is 0.6%.
A stroke may not be apparent during the procedure. The symptoms develop when the atherosclerotic debris loosened from the plaques in the proximal aorta finally break free and embolize. The contrast dyes used in this procedure may also cause transient neurologic deficits.
To conclude, physical examination of the carotid artery and invasive techniques involving major arteries are medical tests that will bring on symptoms of stroke, or lead to actual stroke.