Transient Ischemic Attack – Symptoms, Diagnosis And Prognosis
Transient ischemic attack represents an acute episode of focal neurological or monocular dysfunction, with symptoms lasting less than two hours, resulting from focal and transient cerebral ischemia due to an embolic or thrombotic vascular disease that is not associated with cerebral infarction.
According to definition, in transient ischemic attack is produced a transient neurological function loss, followed by a complete neurological recovery. A very important aspect of transient ischemic attack is represented by the temporary profile of the event, neurological focal deficit has a brief duration, from several minutes, up to 2 hours (convetional limit currently accepted. Imaging studies estimate that only 50% of all transient ischemic attacks fit into the time limit accepted in definition, the rest of the cases being represented by cerebral micro-infarcts.
Transient Ischemic Attack Symptoms
A transient ischemic attack has an acute onset, symptoms may develop in several seconds and last only a few minutes, most of the time symptoms may resolve before the patient presents to the hospital. For this reason, medical history is very important in underlying disorders or medical procedures which can lead to an transient ischemic attack:
- Recent surgical procedures (carotid artery, cardiac interventions);
- Previous strokes (CVA);
- Known coagulopathy;
- Thromboembolic risk factors such as venous or arterial thromboembolism, carotid artery stenosis, atrial fibrillation, prior myocardial infarction, patent foramen ovale or left ventricular dysfunction;
- History of arteritis;
- Comorbidities related to metabolic disorders, especially diabetes;
- Other known cardiovascular disease.
Neurological signs in transient ischemic attack have an rapid onset, within a few seconds. Headache is a very rare symptom, but after remission some unimportant neurological signs (Babinski sign) may persists. Transient ischemic attack may be unique, or may be recurrent during one day.
In most cases, symptoms may indicate the vascular territory that is involved in the development of transient ischemic attack. Thus, for a transient ischemic attack which occur in the carotidian territory, the following symptoms are characteristic:
- Monocular transient blindness (lasting several minutes) is pathognomonic;
- Language impairments (aphasia, alexia and agraphia);
- Hemiparesis and hemihyoesthesia with facio-brachial distribution.
Suggestive for a transient ischemic attack localized in the vertebro-basilary territory, the following symptoms are characteristic:
- Cortical blindness;
- Alternate hemiparesis;
- Equilibrum disturbances;
- Hemyanopia (decreased vision or blindness takes in half of the visual field);
- Drop attack episodes (patient fall to the floor without losing consciousness. The fall may be caused by a disrupted sense of balance or decreased leg muscle tone) are pathognomonic for this vascular territory.
Other signs that may accompany a transient ischemic attack are represented by signs of focal cranial nerves dysfunction:
- Forehead wrinkling asymmetry;
- Asymmetrical mouth retraction;
- Loss of the nasolabial crease;
- Swallowing difficulty;
- Lateral tongue movement;
- Incomplete eyelid closure;
- Ocular dysmotility;
- Visual field deficits;
- Weak shoulder shrugging.
Transient Ischemic Attack Diagnosis
Transient ischemic attack diagnosis relies on the suggestive symptoms for the vascular territory, on the Doppler ultrasound examination of carotid artery, cerebral and extracerebral arteries, in order to asses risk factors such as arterial plaques and arterial stenosis. Imagining studies, such as CT or MRI are indicated in the first 24 hours from symptom onset. Brain imaging can identify an area of ischemia in up to 25% of patients. Vessel imaging can identify a stenosis or occlusion that requires early intervention.
Transient Ischemic Attack Prognosis
The immediate prognosis is good, because the early risk of stroke following a transient ischemic attack is approximately 4% at 2 days, 8% at 30 days, and 9% at 90 days. Patients that experience a transient ischemic attack have a risk of approximately 6-10% per year for stroke and coronary artery disease. The probability for patient to have a stroke in the 5 years following a transient ischemic attack is 24%-29%.