In a TIA, similar signs occur as in a stroke (apoplexy), but the symptoms disappear completely again within a certain period of time. As with a stroke, the cause is usually a blood clot that blocks a small vessel in the brain. Like a stroke, a TIA is also an emergency: if you notice such symptoms, you should therefore alert the emergency services immediately, even if the symptoms have already subsided. In addition, a TIA is an important warning signal, because the risk of stroke is significantly increased after a TIA.
Definition of a TIA
TIA stands for transient ischemic attack. By this, physicians mean a temporary lack of blood flow (ischemia) to areas of the brain, which manifests itself through the symptoms of a stroke. According to the previous definition, a TIA was said to occur if the symptoms did not last longer than 24 hours. Currently, a new definition is being discussed, according to which the time window for symptom regression in a TIA is only one hour. In addition, an MRI of the skull is required for diagnosis: By definition, in contrast to a stroke, there is no evidence of blood flow-related damage to areas of the brain on MRI in a TIA.
Stroke when symptom duration exceeds 24 hours
An attack in which symptoms last between 24 hours and seven days used to be called a prolonged reversible ischemic neurologic deficit (PRIND) or minor stroke. However, these terms for an “intermediate” stage of stroke and TIA are now less common because these cases are considered to be already “true” strokes.
TIA symptoms: Like a stroke
In principle, the symptoms of a TIA are indistinguishable from the signs of a stroke – but they may be less pronounced in some circumstances. A particularly common symptom of a TIA is blindness or severe deterioration of vision in one eye lasting a few seconds to minutes (amaurosis fugax). In addition, a TIA may be manifested by the following symptoms, which usually occur suddenly:
- Paralysis: One half of the body, one half of the face, or only one extremity may be affected – typical symptoms include a drooping corner of the mouth or difficulty walking
- Motor disorders such as difficulty in performing simple hand movements
- Sensory disturbances such as numbness, tingling or a “furry” feeling
- Visual disturbances
- Speech disorders such as slurred speech, difficulty formulating complete sentences, or word-finding problems
- Disorders of speech comprehension
- Dizziness or balance disorders
- Impaired consciousness, confusion, or change in personality
Blood clots and migraine as possible causes.
In a TIA, certain areas in the brain are temporarily deprived of sufficient oxygen due to a circulatory problem. The cause is often a blood clot that blocks a small vessel. Often, the clot comes from a plaque that has formed in the carotid artery as part of hardening of the arteries (atherosclerosis). Less commonly, a blood clot can also be carried from the heart into a cerebral vessel (cardiac embolism) in heart disease such as atrial fibrillation. A TIA can also occur as part of a migraine: In this case, a spasmodic constriction of a blood vessel (vasospasm) causes a circulatory disturbance in the brain.
MRI for diagnosis
In the case of a TIA, it is important that you describe the symptoms to the doctor as accurately as possible, no matter how short they were. You should also tell him about any previous conditions – for example, coronary artery disease or atrial fibrillation. As a rule, an MRI of the skull is performed: It provides information about the extent, localization and magnitude of the deficiency blood flow. Damage to the brain tissue caused by blood flow can also be detected – in this case, according to the definition, it is not a TIA but a stroke. Under certain circumstances, further examinations may be necessary during the diagnostic process:
- CT of the skull to rule out hemorrhage.
- Ultrasound of the vessels (duplex or Doppler sonography).
- Imaging of the cerebral vessels in an X-ray examination with contrast medium (digital subtraction angiography).
- Long-term ECG and cardiac ultrasound to identify possible heart disease as a source of a blood clot
- 24-hour blood pressure measurement
- Determination of blood lipid levels
Treatment by anticoagulation
Patients with a TIA should be monitored for at least 24 hours in a so-called stroke unit – a special ward for stroke patients – if possible. This usually involves starting therapy with anticoagulant medications to prevent further blood clots from forming. In most cases, the active ingredient acetylsalicylic acid (ASS) is initially given as an infusion; alternatively, clopidogrel can also be used. As a rule, treatment with ASA or clopidogrel in tablet form must be continued permanently. In atrial fibrillation, therapy with an anticoagulant such as Marcumar may be necessary in addition or as an alternative.
Increased risk of stroke
After a TIA, the risk of stroke is significantly increased: Up to 40 percent of patients suffer a stroke within five years, and about 10 to 15 percent already within the first two weeks. However, the risk can be significantly reduced by appropriate therapy and other preventive measures. Therefore, it is important to initiate the necessary diagnostics and treatment as soon as possible in the event of a TIA.
ABCD2 score for risk assessment.
The so-called ABCD2 score can be used to estimate the risk of stroke. Points are assigned for the following risk factors:
- Age of the patient over 60 years
- Blood pressure higher than 140/90 mmHg
- Special symptoms (English: clinic): hemiplegia or speech disorders.
- Duration of symptoms
- Diabetes mellitus as a pre-existing condition
Depending on the score, the risk of having a stroke within two days of a TIA is reported to be as high as eight percent.
TIA prevention: minimize risk factors.
In addition to therapy with anticoagulant medications, other risk factors must be minimized after a TIA to prevent stroke. These include, for example, treatment of high blood pressure (arterial hypertension) and optimal adjustment of blood glucose levels in diabetes mellitus. In addition, LDL cholesterol should be lowered below 100 mg/dl, for which a blood lipid-lowering drug (statin) is usually prescribed. In cases of atherosclerosis with severe narrowing of the carotid artery, surgery to remove the plaque may be necessary to prevent the development of new blood clots.
Change lifestyle – prevent stroke
You can do a lot yourself to reduce your risk of stroke with a healthy lifestyle:
- Give up smoking: Nicotine consumption promotes the development of atherosclerosis.
- Make sure you exercise regularly: exercise has a positive effect on blood pressure and blood lipids.
- Reduce your alcohol intake: alcohol can increase the risk of stroke.
- Aim for a normal weight: Excess weight promotes the development of risk factors for cardiovascular disease.
