A
transient ischemic attack (spelled
ischaemic in
British EnglishBritish English, or English , is the broad term used to distinguish the forms of the English language used in the United Kingdom from forms used elsewhere...
) (abbreviated as
TIA, often referred to as "
mini stroke") is a transient episode of neurologic dysfunction caused by
ischemiaIn medicine, ischemia is a restriction in blood supply, generally due to factors in the blood vessels, with resultant damage or dysfunction of tissue. It may also be spelled ischaemia or ischæmia...
(loss of blood flow) – either focal brain,
spinal cordThe spinal cord is a long, thin, tubular bundle of nervous tissue and support cells that extends from the brain . The brain and spinal cord together make up the central nervous system...
or
retinalOcular ischemic syndrome is the constellation of ocular signs and symptoms secondary to severe, chronic arterial hypoperfusion to the eye. Amaurosis fugax is a form of acute vision loss caused by reduced blood flow to the eye that may be a warning sign of an impending stroke...
– without acute infarction (tissue death). TIAs share the same underlying
etiologyEtiology is the study of causation, or origination. The word is derived from the Greek , aitiologia, "giving a reason for" ....
(cause) as strokes: a disruption of
cerebral blood flowCerebral blood flow, or CBF, is the blood supply to the brain in a given time. In an adult, CBF is typically 750 millitres per minute or 15% of the cardiac output. This equates to 50 to 54 millilitres of blood per 100 grams of brain tissue per minute. CBF is tightly regulated to meet the brain's...
(CBF). TIAs and strokes cause the same symptoms, such as contralateral paralysis (opposite side of body from affected brain hemisphere) or sudden weakness or numbness. A TIA may cause sudden dimming or loss of vision,
aphasiaAphasia is an impairment of language ability. This class of language disorder ranges from having difficulty remembering words to being completely unable to speak, read, or write....
, slurred speech and mental confusion. But unlike a stroke, the symptoms of a TIA can resolve within a few minutes or 24 hours. Brain injury may still occur in a TIA lasting only a few minutes. Having a TIA is a risk factor for eventually having a stroke or a
silent strokeA silent stroke is a stroke that does not have any outward symptoms, and the patient is typically unaware they have suffered a stroke. Despite not causing identifiable symptoms a silent stroke still causes damage to the brain, and places the patient at increased risk for both transient ischemic...
. A silent stroke or silent cerebral infarct (SCI) differs from a TIA in that there are no immediately observable symptoms. A SCI may still cause long lasting neurological dysfunction affecting such areas as
moodMood may refer to:*Mood , a relatively long lasting emotional state*Grammatical mood, one of a set of morphologically distinctive forms that are used to signal modality*Mood , a city in Iran*Mood District, a district in Iran...
, personality and cognition. A SCI often occurs before or after a TIA or major stroke.
A cerebral infarct that lasts longer than 24 hours but fewer than 72 hours is called a
reversible ischemic neurologic deficit or RIND.
Causes
The most common cause of a TIA is an
embolusIn medicine, an embolism is the event of lodging of an embolus into a narrow capillary vessel of an arterial bed which causes a blockage in a distant part of the body.Embolization is...
that occludes an artery in the brain. This usually arises from a dislodged
atherosclerotic plaqueIn pathology, an atheroma is an accumulation and swelling in artery walls that is made up of macrophage cells, or debris, that contain lipids , calcium and a variable amount of fibrous connective tissue...
in one of the
carotid arteriesCarotid artery can refer to:* Common carotid artery* External carotid artery* Internal carotid artery...
(
i.e. a number of major arteries in the head and neck) or from a
thrombusA thrombus , or blood clot, is the final product of the blood coagulation step in hemostasis. It is achieved via the aggregation of platelets that form a platelet plug, and the activation of the humoral coagulation system...
(
i.e. a blood clot) in the heart because of
atrial fibrillationAtrial fibrillation is the most common cardiac arrhythmia . It is a common cause of irregular heart beat, identified clinically by taking a pulse. Chaotic electrical activity in the two upper chambers of the heart result in the muscle fibrillating , instead of achieving coordinated contraction...
. In a TIA, the blockage period is very short-lived and hence there is no permanent damage. The cholesterol build-up is gradual and eventually narrows the
lumenA lumen in biology is the inside space of a tubular structure, such as an artery or intestine...
. With time, blood flow to that side of the brain is reduced and a stroke may result. In other cases, cholesterol particles from the atherosclerotic plaque may suddenly break off and enter the brain. In some people, these fragments come off from the
heartThe heart is a myogenic muscular organ found in all animals with a circulatory system , that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
and go to the brain. This often happens during a
heart attackMyocardial infarction or acute myocardial infarction , commonly known as a heart attack, results from the interruption of blood supply to a part of the heart, causing heart cells to die...
or an infection of the
valvesA heart valve normally allows blood flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart...
.
Other reasons include excessive narrowing of large vessels resulting from an atherosclerotic plaque and increased blood viscosity caused by some blood diseases. TIA is related to other medical conditions such as
hypertensionHypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
,
heart diseaseHeart disease, cardiac disease or cardiopathy is an umbrella term for a variety of diseases affecting the heart. , it is the leading cause of death in the United States, England, Canada and Wales, accounting for 25.4% of the total deaths in the United States.-Types:-Coronary heart disease:Coronary...
(especially
atrial fibrillationAtrial fibrillation is the most common cardiac arrhythmia . It is a common cause of irregular heart beat, identified clinically by taking a pulse. Chaotic electrical activity in the two upper chambers of the heart result in the muscle fibrillating , instead of achieving coordinated contraction...
),
migraineMigraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea...
, cigarette smoking,
hypercholesterolemiaHypercholesterolemia is the presence of high levels of cholesterol in the blood. It is not a disease but a metabolic derangement that can be caused by many diseases, notably cardiovascular disease...
, and
diabetes mellitusDiabetes mellitus, often simply referred to as diabetes, is a group of metabolic diseases in which a person has high blood sugar, either because the body does not produce enough insulin, or because cells do not respond to the insulin that is produced...
.
Symptoms
Symptoms vary widely from person to person, depending on the area of the brain involved. The most frequent symptoms include temporary loss of vision (typically
amaurosis fugaxAmaurosis fugax is a transient monocular visual loss.-Pathophysiology and etiology:...
); difficulty speaking (
aphasiaAphasia is an impairment of language ability. This class of language disorder ranges from having difficulty remembering words to being completely unable to speak, read, or write....
); weakness on one side of the body (
hemiparesisHemiparesis is weakness on one side of the body. It is less severe than hemiplegia - the total paralysis of the arm, leg, and trunk on one side of the body. Thus, the patient can move the impaired side of his body, but with reduced muscular strength....
); and numbness or tingling (
paresthesiaParesthesia , spelled "paraesthesia" in British English, is a sensation of tingling, burning, pricking, or numbness of a person's skin with no apparent long-term physical effect. It is more generally known as the feeling of "pins and needles" or of a limb "falling asleep"...
), usually on one side of the body. Impairment of
consciousnessConsciousness is a term that refers to the relationship between the mind and the world with which it interacts. It has been defined as: subjectivity, awareness, the ability to experience or to feel, wakefulness, having a sense of selfhood, and the executive control system of the mind...
is very uncommon. There have been cases of temporary and partial
paralysisParalysis is loss of muscle function for one or more muscles. Paralysis can be accompanied by a loss of feeling in the affected area if there is sensory damage as well as motor. A study conducted by the Christopher & Dana Reeve Foundation, suggests that about 1 in 50 people have been diagnosed...
affecting the face and
tongueThe tongue is a muscular hydrostat on the floors of the mouths of most vertebrates which manipulates food for mastication. It is the primary organ of taste , as much of the upper surface of the tongue is covered in papillae and taste buds. It is sensitive and kept moist by saliva, and is richly...
of the afflicted. The symptoms of a TIA are short-lived and usually last a few seconds to a few minutes and most symptoms disappear within 60 minutes. Some individuals may have a lingering feeling that something odd happened to the body.
DizzinessDizziness refers to an impairment in spatial perception and stability. The term is somewhat imprecise. It can be used to mean vertigo, presyncope, disequilibrium, or a non-specific feeling such as giddiness or foolishness....
, lack of coordination or poor balance are also symptoms related to TIA. Symptoms vary in severity.
Diagnosis
TIA will usually be diagnosed after a doctor performs a history and a
physical examPhysical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...
. There are several
radiologicalRadiology is a medical specialty that employs the use of imaging to both diagnose and treat disease visualized within the human body. Radiologists use an array of imaging technologies to diagnose or treat diseases...
tests that are done to evaluate patients who have had a TIA. This includes a CT scan or an MRI of the brain,
ultrasoundUltrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
of the neck, an
echocardiogramAn echocardiogram, often referred to in the medical community as a cardiac ECHO or simply an ECHO, is a sonogram of the heart . Also known as a cardiac ultrasound, it uses standard ultrasound techniques to image two-dimensional slices of the heart...
of the heart. In most cases, the source of atherosclerosis is usually identified with an ultrasound.
Prognosis
Patients diagnosed with a TIA are sometimes said to have had a warning for an approaching
strokeA stroke, previously known medically as a cerebrovascular accident , is the rapidly developing loss of brain function due to disturbance in the blood supply to the brain. This can be due to ischemia caused by blockage , or a hemorrhage...
. If the time period of blood supply impairment lasts more than a few minutes, the nerve cells of that area of the brain die and cause permanent neurologic deficit. One third of the people with TIA later have recurrent TIAs and one third have a stroke because of permanent nerve cell loss.
Alternative diagnoses
Other diagnoses may have symptoms similar to those of a TIA:
- Atypical migraine
Migraine is a chronic neurological disorder characterized by moderate to severe headaches, and nausea...
if visual symptoms occur such as perception of wavy or jagged lines or tiny specks of light and if a headache occurs. Typically a history of prior migraines is present.
- Partial seizure
An epileptic seizure, occasionally referred to as a fit, is defined as a transient symptom of "abnormal excessive or synchronous neuronal activity in the brain". The outward effect can be as dramatic as a wild thrashing movement or as mild as a brief loss of awareness...
in the parietal area of the brain
- Glucose abnormalities; these could be distinguished by a history of diabetes mellitus and a loss of consciousness
- Electrolyte abnormalities
- Hypertensive encephalopathy
Hypertensive encephalopathy is a neurological dysfunction induced by malignant hypertension. The term "hypertensive encephalopathy" was introduced to describe this type of encephalopathy by Oppenheimer and Fishberg in 1928. It describes cerebral conditions, typically reversible, caused by sudden...
(headache, delirium, hypertension, cerebral edema)
- Subdural hematoma
A subdural hematoma or subdural haematoma , also known as a subdural haemorrhage , is a type of haematoma, a form of traumatic brain injury. Blood gathers within the outermost meningeal layer, between the dura mater, which adheres to the skull, and the arachnoid mater, which envelops the brain...
(history of trauma, headache, loss of consciousness)
- Brain tumor
A brain tumor is an intracranial solid neoplasm, a tumor within the brain or the central spinal canal.Brain tumors include all tumors inside the cranium or in the central spinal canal...
(mode of onset, progressive headaches, increased intracranial pressure)
- Demyelinating disease
A demyelinating disease is any disease of the nervous system in which the myelin sheath of neurons is damaged. This impairs the conduction of signals in the affected nerves, causing impairment in sensation, movement, cognition, or other functions depending on which nerves are involved.The term...
- Conversion disorder
Conversion disorder is a condition in which patients present with neurological symptoms such as numbness, blindness, paralysis, or fits without a neurological cause. It is thought that these problems arise in response to difficulties in the patient's life, and conversion is considered a psychiatric...
Prevention
A TIA may be prevented by changes in lifestyle; although most of these recommendations have no solid empirical data, most medical professionals believe them to be so. These include:
- Avoiding smoking
Smoking is a practice in which a substance, most commonly tobacco or cannabis, is burned and the smoke is tasted or inhaled. This is primarily practised as a route of administration for recreational drug use, as combustion releases the active substances in drugs such as nicotine and makes them...
- Cutting down on fats and cholesterol
Cholesterol is a complex isoprenoid. Specifically, it is a waxy steroid of fat that is produced in the liver or intestines. It is used to produce hormones and cell membranes and is transported in the blood plasma of all mammals. It is an essential structural component of mammalian cell membranes...
to help reduce plaque build up
- Eating a healthy diet composed of fruits and vegetables
- Limiting sodium
Sodium is a chemical element with the symbol Na and atomic number 11. It is a soft, silvery-white, highly reactive metal and is a member of the alkali metals; its only stable isotope is 23Na. It is an abundant element that exists in numerous minerals, most commonly as sodium chloride...
in the diet, which reduces blood pressure
- Exercising regularly
- Moderating alcohol intake
- Maintaining a normal weight
- Controlling blood pressure and keeping blood sugar
The blood sugar concentration or blood glucose level is the amount of glucose present in the blood of a human or animal. Normally in mammals, the body maintains the blood glucose level at a reference range between about 3.6 and 5.8 mM , or 64.8 and 104.4 mg/dL...
s under control
Treatment
The mainstay of treatment following acute recovery from a TIA should be to diagnose and treat the underlying cause. It is not always immediately possible to tell the difference between a CVA (stroke) and a TIA. Most patients who are diagnosed at a hospital's
emergency departmentAn emergency department , also known as accident & emergency , emergency room , emergency ward , or casualty department is a medical treatment facility specialising in acute care of patients who present without prior appointment, either by their own means or by ambulance...
as having suffered from a TIA will be discharged home and advised to contact their primary physician to organize further investigations. TIA can be considered as the last warning. The reason for the condition should be immediately examined by imaging of the brain.
The initial treatment is
aspirinAspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...
, second line is
clopidogrelClopidogrel is an oral, thienopyridine class antiplatelet agent used to inhibit blood clots in coronary artery disease, peripheral vascular disease, and cerebrovascular disease. It is marketed by Bristol-Myers Squibb and Sanofi-Aventis under the trade name Plavix. The drug works by irreversibly...
, third line is
ticlopidineTiclopidine is an antiplatelet drug in the thienopyridine family. Like clopidogrel, it is an adenosine diphosphate receptor inhibitor. It is used in patients in whom aspirin is not tolerated, or in whom dual antiplatelet therapy is desirable...
. If TIA is recurrent after aspirin treatment, the combination of
aspirinAspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...
and
dipyridamoleDipyridamole is a drug that inhibits thrombus formation when given chronically and causes vasodilation when given at high doses over a short time.-Mechanism and effects:...
is needed (Aggrenox).
An
electrocardiogramElectrocardiography is a transthoracic interpretation of the electrical activity of the heart over a period of time, as detected by electrodes attached to the outer surface of the skin and recorded by a device external to the body...
(ECG) may show atrial fibrillation, a common cause of TIAs, or other arrhythmias that may cause embolisation to the brain. An echocardiogram is useful in detecting thrombus within the heart chambers. Such patients benefit from anticoagulation.
If the TIA affects an area supplied by the
carotid arteriesCarotid artery can refer to:* Common carotid artery* External carotid artery* Internal carotid artery...
, an
ultrasoundUltrasound is cyclic sound pressure with a frequency greater than the upper limit of human hearing. Ultrasound is thus not separated from "normal" sound based on differences in physical properties, only the fact that humans cannot hear it. Although this limit varies from person to person, it is...
(
TCDTranscranial Doppler is a test that measures the velocity of blood flow through the brain's blood vessels. Used to help in the diagnosis of emboli, stenosis, vasospasm from a subarachnoid hemorrhage , and other problems, this relatively quick and inexpensive test is growing in popularity in the...
) scan may demonstrate carotid
stenosisA stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.It is also sometimes called a stricture ....
. For people with a greater than 70% stenosis within the carotid artery, removal of atherosclerotic plaque by surgery, specifically a
carotid endarterectomyCarotid endarterectomy is a surgical procedure used to prevent stroke, by correcting stenosis in the common carotid artery...
, may be recommended. The blood vessel is opened up and the plaque is removed. The carotid may be replaced with a vessel retrieved from the lower leg or foot. The procedure is not technically difficult but carries the potential complication of inducing a stroke. A stroke can occur during surgery or after the procedure. The chance of a stroke ranges from 1–4 percent.
Some patients may also be given modified-release dipyridamole or clopidogrel.
To reduce recurrence of an attack, ACE inhibitor drugs are used. The aim is to prevent a sudden, significant drop in blood pressure, because blood pressure that is too low may increase ischemic injury due to low perfusion.
Medication
The use of anti-coagulant medications,
heparinHeparin , also known as unfractionated heparin, a highly sulfated glycosaminoglycan, is widely used as an injectable anticoagulant, and has the highest negative charge density of any known biological molecule...
and
warfarinWarfarin is an anticoagulant. It is most likely to be the drug popularly referred to as a "blood thinner," yet this is a misnomer, since it does not affect the thickness or viscosity of blood...
, or anti-
plateletPlatelets, or thrombocytes , are small,irregularly shaped clear cell fragments , 2–3 µm in diameter, which are derived from fragmentation of precursor megakaryocytes. The average lifespan of a platelet is normally just 5 to 9 days...
medications such as
aspirinAspirin , also known as acetylsalicylic acid , is a salicylate drug, often used as an analgesic to relieve minor aches and pains, as an antipyretic to reduce fever, and as an anti-inflammatory medication. It was discovered by Arthur Eichengrun, a chemist with the German company Bayer...
may be warranted.
Antiplatelet drugAn antiplatelet drug is a member of a class of pharmaceuticals that decrease platelet aggregation and inhibit thrombus formation...
s prevent platelets from sticking to each other, thus making the blood thinner (i.e., less viscous). Thinning the blood helps to ensure that small particles do not form and travel to the brain. These drugs require frequent monitoring. These drugs also have side effects such as easy bruising and bleeding from mild trauma.
Risk factors
- Family history
In medicine, a family history consists of information about disorders from which the direct blood relatives of the patient have suffered. Genealogy typically includes very little of the medical history of the family, but the medical history could be considered a specific subset of the total history...
of stroke or TIA substantially increases risk.
- People 55 years or older are at higher risk.
- Males have a slightly higher risk of TIA than females but females are more likely to die from a stroke.
- African American
African Americans are citizens or residents of the United States who have at least partial ancestry from any of the native populations of Sub-Saharan Africa and are the direct descendants of enslaved Africans within the boundaries of the present United States...
s generally tend to have a high risk of dying from a stroke, chiefly due to high blood pressureHypertension or high blood pressure is a cardiac chronic medical condition in which the systemic arterial blood pressure is elevated. What that means is that the heart is having to work harder than it should to pump the blood around the body. Blood pressure involves two measurements, systolic and...
and uncontrolled diabetes.
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