Transient Ischemic Attack (TIA, mini-stroke)

Definition of the disease. Causes of the disease:

A transient ischemic attack (TIA) is an acute temporary neurological disorder that occurs due to a local decrease in blood flow to the brain, spinal cord, or retina and is not accompanied by tissue necrosis. In colloquial terms, such a disorder is called a mini-stroke.

The neurological disorder manifests as weakness in the limbs on one side, speech impairment, and facial asymmetry. Clinical symptoms of TIA usually last less than an hour, often even less than 30 minutes, but prolonged episodes can also occur.

A transient ischemic attack (TIA), like an ischemic stroke, belongs to acute cerebrovascular disorders (ACVD). These are different in severity manifestations of brain ischemia, i.e., a decrease in its blood circulation. The difference is that TIA is a reversible condition, where all symptoms disappear within 24 hours. In ischemic stroke (cerebral infarction), the consequences are irreversible, as the cells of the affected area of the brain die and lose their functions.

TIAs account for 13 to 15% of all cases of ACVD. The risk of ischemic stroke after TIA is assessed differently. According to a 2021 meta-analysis, it is 2.4% within 2 days, 3.8% within a week, 4.1% within 30 days, and 4.7% within 90 days.

Timely recognized TIA allows preventing a stroke and thereby avoiding gross disturbances: motor (reduced hand and/or leg performance) and speech (indistinct speech or its complete absence).

Causes of TIA:

  1. Atherosclerosis of the vertebral arteries, as well as extracranial or intracranial segments of the carotid arteries.
  2. Cardiogenic embolism, accounting for about 20% of TIAs.
  3. Causes of embolism include atrial fibrillation, myocardial infarction, rheumatic heart diseases, cardiopathies, endocarditis, calcific aortic stenosis, mitral valve calcinosis, congenital heart defects with septal defects, mitral valve prolapse.
  4. Coagulopathies (blood clotting disorders).
  5. Angiopathies (damage to blood vessels) associated with arterial hypertension, diabetes mellitus, or other causes.
  6. Developmental anomalies of the carotid or vertebral arteries, aortic coarctation, compression of the vertebral arteries by pathologically altered cervical vertebrae.
  7. Dissection (separation) of the carotid or vertebral artery.
  8. Use of sympathomimetics.
  9. Vasculitis (inflammation and destruction of the walls of blood vessels).

In approximately 5% of cases, more often in young people, TIA, like ischemic brain stroke, is provoked by other reasons such as congenital arterial anomalies, migraine, hematological disorders, infections, malignant neoplasms, oral contraceptives, pregnancy and postpartum period, Moya-Moya disease, mitochondrial cytopathy, and cholesterol embolism syndrome.

Causes of TIA in Children:

  • Congenital heart defect with cerebral thromboembolism (most common).
  • Blood clotting disorders.
  • Central nervous system infection.
  • Neurofibromatosis (a hereditary condition characterized by the formation of benign tumors in the skin, soft tissues, nervous system, and internal organs).
  • Vasculitis.
  • Moyamoya disease.
  • Fibromuscular dysplasia (degeneration of the elastic tissue of blood vessels with simultaneous proliferation of fibrous and smooth muscle tissue).
  • Marfan syndrome.
  • Tuberous sclerosis (a rare genetic disorder characterized by the formation of benign tumors in organs and tissues).
  • Tumor.
  • Sickle cell anemia.
  • Focal arteriopathies.

Risk Factors for TIA:
Modifiable Risk Factors:

  • Alcohol abuse.
  • Arterial hypertension.
  • Smoking.
  • Dyslipidemia (abnormal lipid levels in the blood).
  • Diabetes mellitus (regardless of type).
  • Insulin resistance.
  • Obesity.
  • Lack of physical activity.
  • Poor diet (e.g., high in saturated fats, trans fats, and calories).
  • Stress, depression.
  • Use of certain drugs (e.g., cocaine or amphetamines).

Non-modifiable Risk Factors:

  • History of stroke in the patient or their relatives.
  • Elderly age. The risk of TIA increases after the age of 65 due to changes in vascular wall structure with aging. Additionally, older individuals are more likely to have multiple chronic conditions, indirectly influencing the occurrence of TIA.
  • Male gender.

There is a high risk of developing TIA during and after heart surgery. People with heart valve prostheses are also at risk. Whether TIA occurs after surgery depends on the person’s lifestyle and comorbidities.

Сymptoms of Transient Ischemic Attack

A TIA can last only a few minutes, and symptoms often resolve before the patient seeks medical attention. Symptoms depend on which blood vessel in the brain is affected. Symptoms of a transient ischemic attack may include:

  • Transient blindness – loss of vision in one or both eyes.
  • Weakness (muscle weakness) in the arm and/or leg and/or facial muscles.
  • Sensory disturbances (numbness, tingling sensation) in facial, arm, and/or leg muscles.
  • Impaired balance and/or coordination of movements – unsteadiness while walking.
  • Speech impairment, up to total aphasia (inability to speak and understand speech).
  • Transient global amnesia (TGA).
  • Epileptic seizures.
  • Loss of consciousness.
  • Memory impairment, psychomotor agitation, behavioral disturbances.

Transient blindness (transient monocular blindness) is a sudden, brief loss of vision due to impaired blood flow in the supply area of the ophthalmic, posterior ciliary arteries, or retinal vessels.

Transient global amnesia (TGA) is a sudden memory disorder of current and sometimes remote events. The symptoms usually last for several hours (no more than 24 hours), and patients repeat the same questions, needing constant reminders of what they have just done. Daily and professional skills are not lost. That is, the person’s behavior may seem strange due to repetitive questions, but the patient does not notice it and does not complain about anything during TGA. Memory fully returns afterward. Neurological deficit is not observed in this condition, i.e., coordination of movements and sensitivity are not impaired.

The average duration of a TIA episode is 8-14 minutes. The majority of transient ischemic attacks resolve within the first hour or faster. According to Russian neurologist V.A. Parfenov, the duration of TIA symptoms of less than 1 hour was noted in 43.5% of patients, from 1 to 3 hours in 45.7%, and more than 3 hours in 10.9%.

In children, the symptoms of TIA are the same as in adults.

Pathogenesis of Transient Ischemic Attack

The pathogenesis of TIA involves temporary ischemia (reduced or interrupted blood flow) in a specific area of the brain due to partial or complete occlusion of a cerebral vessel, most often by a detached thrombus.

In this case, cerebral blood supply decreases, leading to a decrease in oxygen exchange levels and disruption of the function of brain neurons. At this stage, ischemia is reversible. Clinical symptoms will vary depending on the affected vessel and the area of the brain it supplies.

Classification and Stages of Development of Transient Ischemic Attack

In the International Classification of Diseases 10th Revision (ICD-10), transient ischemic attack is encoded as G45 Transient cerebral ischemic attacks and related syndromes. This group includes:

  • G45.0 Vertebro-basilar arterial system syndrome.
  • G45.1 Carotid artery syndrome (hemispheric).
  • G45.2 Multiple and bilateral syndromes of cerebral arteries.
  • G45.3 Transient blindness.
  • G45.4 Transient global amnesia.
  • G45.8 Other transient cerebral ischemic attacks and related syndromes.
  • G45.9 Unspecified transient cerebral ischemic attack (cerebral artery spasm, transient cerebral ischemia).

Based on the nature of clinical manifestations, TIAs are distinguished in the carotid system and in the vertebro-basilar system:

  • Carotid system: Manifestations in the carotid basin include temporary weakness of the muscles in the arm and leg on one side of the body (hemiparesis) or of a single limb (monoparesis), sensory and speech disturbances, and sometimes transient blindness in one eye.
  • Vertebro-basilar basin: Symptoms include dizziness, nausea, ataxia (coordination disorder), dysarthria (indistinct speech, “slurred speech”), double vision, decreased sensitivity on the face, sensory disturbances in the limbs on one or both sides. Sometimes transient blindness in one eye may occur. TIAs in the vertebro-basilar basin occur almost four times less frequently than in the carotid system.

Classification of TIA by Severity of Symptoms:

  • Mild: Lasts up to 10 minutes.
  • Moderate: Lasts several hours.
  • Severe: Lasts up to 24 hours.

Classification of TIA by Frequency:

  • Rare: 1-2 times a year.
  • Moderate frequency: 3-6 times a year.
  • Frequent: Once a month or more.

The frequency of TIAs depends on risk factors.

Complications of Transient Ischemic Attack

A transient ischemic attack (TIA) is a dangerous precursor to an ischemic stroke. The symptoms of a stroke are similar to those of TIA – decreased sensitivity in the arm and/or leg, loss of function in the limbs, speech disturbances, and facial asymmetry. TIA is distinguished from a stroke only by the reversibility of symptoms.

Diagnosis of Transient Ischemic Attack

The diagnosis of “transient ischemic attack” is usually based on medical history since patients often experience TIAs “on their feet” and do not seek medical attention. The main tasks of the physician when making the diagnosis are:

  • Exclude stroke within the first 3 hours of the onset of TIA.
  • Rule out other conditions with similar symptoms, i.e., perform differential diagnosis.
  • Determine the causes of TIA to initiate necessary stroke prevention measures.

Medical History Collection:

During the conversation with the patient and their close ones, attention should be paid to behavior, speech, gait, and memory. Any abnormalities, such as indistinct speech or instability while walking, may indicate TIA or stroke.

Laboratory Diagnosis:

  • Blood analysis: complete blood count with determination of erythrocyte sedimentation rate (ESR), biochemical blood analysis to assess cholesterol levels (lipid profile), glucose, electrolytes, and cardiac enzymes.
  • Analysis of blood coagulation parameters: prothrombin time, partial thromboplastin time.
  • Determination of antiphospholipid antibodies.
  • Comprehensive coagulation profile examination: antithrombin III, thrombin time, proteins C and S, protein fractions, etc.

Instrumental Diagnosis:

  • Cardiac examination – electrocardiography (ECG). ECG can detect paroxysmal atrial fibrillation, which may cause embolism of cerebral vessels.
  • Doppler ultrasound scanning of the head and neck vessels (common and internal carotid, vertebral arteries). If these studies reveal narrowing of the main head vessels by more than 60%, consultation with a neurosurgeon is necessary to decide on surgical treatment.
  • Non-contrast computer tomography (if MRI is unavailable). CT is used to exclude other pathologies that may also be accompanied by temporary neurological symptoms.
  • Magnetic resonance imaging (MRI) with diffusion-weighted imaging. It is considered a preferable method for differential diagnosis.
  • Transthoracic echocardiography (EchoCG) – heart examination using ultrasound with the sensor placed on the chest surface. EchoCG is performed to exclude cardiogenic embolism when the data indicate cardiac pathology or when the patient is over 45 years old.

Differential Diagnosis:

  • Migraine
  • Epileptic seizure
  • Brain tumor
  • Transient global amnesia
  • Multiple sclerosis
  • Hypoglycemia
  • Fainting
  • Meniere’s disease
  • Drop attacks
  • Meniere-like syndromes
  • Dissection of the carotid artery
  • Meningitis
  • Stroke
  • Subarachnoid hemorrhage

Treatment of Transient Ischemic Attack (TIA):

  • Patients often seek medical help after the disappearance of symptoms, but antithrombotic therapy should be initiated immediately after ruling out intracranial hemorrhage.
  • Medical treatment:
    • Patients with TIA should receive antiplatelet agents or anticoagulants depending on concomitant heart conditions.
    • Anticoagulants inhibit blood clotting and are necessary for secondary prevention of TIA and strokes.
    • Antiplatelet agents improve fluid passage in brain tissues and prevent the development of acute cerebral ischemia.
  • Surgical treatment:
    • Carotid endarterectomy is performed in cases of more than 50% stenosis of the internal carotid arteries.