Stroke is one of the top causes of death after heart disease and cancer. There are different types of stroke. Most are caused by infarction or about 75% of all cases. In addition, of the patients who experience infarction, about 15-30% of cases are caused by coronary artery obstruction or atherosclerosis (14-40%). Then there are less common causes of stroke, such as intracerebral hemorrhage, which accounts for about 11% of all cases and subarachnoid hemorrhage, which accounts for about 5% of cases.
Transcranial Doppler Ultrasound (TCD)
Transcranial doppler ultrasound uses high-frequency waves through a thin section of the skull around the temporal window. The test probe uses a low frequency of 2 megahertz, which is a wave frequency that allows for good penetration. The test is used to determine the flow rate, direction and characteristics of blood inside the cerebral arteries. High-frequency sound waves are used to determine the site of arterial stenosis or obstruction based on the nature of blood flow.
Benefits of Transcranial Doppler Ultrasound (TCD)
- It is used to assess cerebral arteries to determine the presence of stenosis and occlusion.
- It is used to assess blood circulation in the cerebral arteries, especially collateral circulation after arterial stenosis has occurred.
- It is used to monitor and diagnose some critical conditions like vasospasm in patients with cerebral hemorrhaging or patients with increased intracranial pressure
- It is used to monitor small blood clots that reach the cerebral arteries.
- It is used to test for congenital heart conditions, for example, detection of patent foramen ovale (cerebral micro-embolism in the right to left cardiac shunts).
- It is used to test for auto-regurgitation in the cerebral arteries by observing vascular reactivity after causing blood carbon dioxide level changes, etc.
Warning Signs of Stroke
- Weakness in the arms and legs in half of the body, mouth contortions or numbness in half of the body that occurs suddenly.
- Loss of speech, inability to comprehend language and incoherent speech that occurs suddenly.
- Loss of vision in one eye or able to see only one half of the field of vision or seeing double vision suddenly.
- Dizziness, vertigo, swaying and loss of balance similar to being drunk suddenly.
- Severe headache that never occurred before along with vomiting or loss of consciousness that occurs suddenly.
**In some cases, the symptoms occur only temporarily and then the patient returns to normal. For example, the patient might experience weakness for only 30 minutes before feeling better and normal again. As a result, they might feel at ease and not go see the doctor due to not knowing that what they experienced were warning signs of stroke. For people who experience these symptoms temporarily and then feel better, the medical term for their condition is “transient ischemic attack”. It is a condition in which the brain temporarily suffers from a lack of blood supply. Studies found that 1 out of 9 patients in this category experience permanent stenosis or occlusion (stroke) within 90 days and that stroke occurs within 2 days later in over half of cases following the warning signs. Therefore, these patients should consult a doctor in order to receive a thorough diagnosis and to be considered for drugs that will prevent the disease.
