Lacunar stroke
Encyclopedia
Lacunar stroke or lacunar infarct (LACI) is a type of stroke
that results from occlusion of one of the penetrating arteries
that provides blood to the brain's deep structures. Patients who present with symptoms of a lacunar stroke, but who have not yet had diagnostic imaging performed may be described as suffering from Lacunar Stroke Syndrome (LACS).
Much of the current knowledge of lacunar strokes comes from C. M. Fisher's
cadaver
dissections of post-mortem stroke patients. He observed "lacunes" (Latin for 'lake') of empty fluid left in the deep brain structures after occlusion of 200-800 μm penetrating arteries and connected them with 5 classic syndrome
s. These syndromes are still noted today, though lacunar infarcts are diagnosed based on clinical judgment and radiologic
imaging.
, cerebellar arteries, and basilar artery
. The corresponding lesions occur in the deep nuclei of the brain (37% putamen
, 14% thalamus
, and 10% caudate
) as well as the pons
(16%) or the posterior limb of the internal capsule
(10%). They occur less commonly in the deep cerebral white matter, the anterior limb of the internal capsule, and the cerebellum
.
The two proposed mechanisms are microatheroma and lipohyalinosis
. At the beginning, lipohyalinosis
was thought to be the main small vessel pathology, but microatheroma now is thought to be the most common mechanism of arterial occlusion
(or stenosis
). Occasionally, atheroma
in the parent artery blocks the orifice
of the penetrating artery (luminal atheroma), or atheroma involves the origin of the penetrating artery (junctional atheroma). Alternatively, hypoperfusion is believed to be the mechanism when there is stenosis of the penetrating artery. When no evidence of small vessel disease is found on histologic examination, an embolic cause is assumed, either artery-to-artery embolism
or cardioembolism. In one recent series, 25% of patients with clinical radiologically defined lacunes had a potential cardiac cause for their strokes.
Advanced age, chronic hypertension
, smoking
and diabetes mellitus
are risk factors. It is unclear whether there is an association with alcohol consumption, elevated cholesterol, or history of prior stroke. Lacunar strokes may result from carotid artery
pathology or microemboli from the heart as in atrial fibrillation
. Patients often recover well, but if there is enough white matter disease from lacunar pathology, one can see a subcortical dementia such as Binswanger disease.
s can mimic lacunar infarcts, but true cortical infarct signs (such as aphasia, neglect, and visual field defects) are always absent. The 5 classic syndromes are as follows:
which usually shows no identifiable outward symptoms thus the term "silent". Individuals who suffer a SLI are often completely unaware they have suffered a stroke. This type of stroke often causes lesions in the surrounding brain tissue that are visibly detected via neuroimaging techniques such as MRI and computerized axial tomography (CAT scan). Silent strokes including silent lacunar infarctions have been shown to be much more common then previously thought, with an estimated prevalence rate of eleven million per year in the United States, approximately 10% of these silent strokes are silent lacunar infarctions. While dubbed "silent" due to the immediate lack of classic stroke symptoms SLIs can cause damage to the surrounding brain tissue (lesion
s) and can affect various aspects of a persons mood, personality and cognitive functioning
. A SLI or any type of silent stroke places an individual at greater risk for future major stroke.
may be administered within three hours of stroke onset if the patient is without contraindications (i.e. a bleeding diathesis such as recent major surgery or cancer with brain metastases). High dose aspirin
can be given within 48 hours. For long term prevention of recurrence, medical regimens are typically aimed towards correcting the underlying risk factors for lacunar infarcts such as hypertension, diabetes mellitus and cigarette smoking. Blood thinners such as heparin
and warfarin
have shown no benefit over aspirin with regards to five year survival.
Patients who suffer lacunar strokes have a greater chance of surviving beyond thirty days (96%) than those with other types of stroke (85%), and better survival beyond a year (87% versus 65-70%). Between 70% and 80% are functionally independent at 1 year, compared with fewer than 50% otherwise.
Stroke
A 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...
that results from occlusion of one of the penetrating arteries
Artery
Arteries are blood vessels that carry blood away from the heart. This blood is normally oxygenated, exceptions made for the pulmonary and umbilical arteries....
that provides blood to the brain's deep structures. Patients who present with symptoms of a lacunar stroke, but who have not yet had diagnostic imaging performed may be described as suffering from Lacunar Stroke Syndrome (LACS).
Much of the current knowledge of lacunar strokes comes from C. M. Fisher's
Miller Fisher
Charles Miller Fisher, usually known as Miller Fisher is a neurologist. Trained in Canada, he spent 1949 at Massachusetts General Hospital, followed by several years in Montreal. In 1954 he returned to Massachusetts General on the stroke service, beginning a long career in stroke neurology...
cadaver
Cadaver
A cadaver is a dead human body.Cadaver may also refer to:* Cadaver tomb, tomb featuring an effigy in the form of a decomposing body* Cadaver , a video game* cadaver A command-line WebDAV client for Unix....
dissections of post-mortem stroke patients. He observed "lacunes" (Latin for 'lake') of empty fluid left in the deep brain structures after occlusion of 200-800 μm penetrating arteries and connected them with 5 classic syndrome
Syndrome
In medicine and psychology, a syndrome is the association of several clinically recognizable features, signs , symptoms , phenomena or characteristics that often occur together, so that the presence of one or more features alerts the physician to the possible presence of the others...
s. These syndromes are still noted today, though lacunar infarcts are diagnosed based on clinical judgment and radiologic
Radiology
Radiology 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...
imaging.
Epidemiology
It is estimated that lacunar infarcts account for 25% of all ischemic strokes, with an annual incidence of approximately 15 per 100,000 people. They may be more frequent in men and in people of African, Mexican, and Hong Kong Chinese descent.Pathophysiology
Lacunes are caused by occlusion of a single deep penetrating artery that arises directly from the constituents of the Circle of WillisCircle of Willis
The Circle of Willis is a circle of arteries that supply blood to the brain...
, cerebellar arteries, and basilar artery
Basilar artery
In human anatomy, the basilar artery is one of the arteries that supplies the brain with oxygen-rich blood.The two vertebral arteries and the basilar artery are sometimes together called the vertebrobasilar system, which supplies blood to the posterior part of circle of Willis and anastomoses with...
. The corresponding lesions occur in the deep nuclei of the brain (37% putamen
Putamen
The putamen is a round structure located at the base of the forebrain . The putamen and caudate nucleus together form the dorsal striatum. It is also one of the structures that comprises the basal ganglia. Through various pathways, the putamen is connected to the substantia nigra and globus pallidus...
, 14% thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
, and 10% caudate
Caudate
Caudate can refer to:* Caudate nucleus* Caudate lobe of liver* Cauda equina* Members of the Caudata order....
) as well as the pons
Pons
The pons is a structure located on the brain stem, named after the Latin word for "bridge" or the 16th-century Italian anatomist and surgeon Costanzo Varolio . It is superior to the medulla oblongata, inferior to the midbrain, and ventral to the cerebellum. In humans and other bipeds this means it...
(16%) or the posterior limb of the internal capsule
Internal capsule
The internal capsule is an area of white matter in the brain that separates the caudate nucleus and the thalamus from the lenticular nucleus. The internal capsule contains both ascending and descending axons....
(10%). They occur less commonly in the deep cerebral white matter, the anterior limb of the internal capsule, and the cerebellum
Cerebellum
The cerebellum is a region of the brain that plays an important role in motor control. It may also be involved in some cognitive functions such as attention and language, and in regulating fear and pleasure responses, but its movement-related functions are the most solidly established...
.
The two proposed mechanisms are microatheroma and lipohyalinosis
Lipohyalinosis
Lipohyalinosis is a small-vessel disease in the brain. Originally defined by Fischer as 'segmental arteriolar wall disorganisation', it is characterised by vessel wall thickening and a resultant reduction in luminal diameter...
. At the beginning, lipohyalinosis
Lipohyalinosis
Lipohyalinosis is a small-vessel disease in the brain. Originally defined by Fischer as 'segmental arteriolar wall disorganisation', it is characterised by vessel wall thickening and a resultant reduction in luminal diameter...
was thought to be the main small vessel pathology, but microatheroma now is thought to be the most common mechanism of arterial occlusion
Vascular occlusion
Vascular occlusion is a sudden blockage of a blood vessel, usually with a clot. It differs from thrombosis in that it can be used to describe any form of blockage, not just one formed by a clot. When it occurs in a major vein, it can, in some cases, cause deep vein thrombosis. The condition is...
(or stenosis
Stenosis
A stenosis is an abnormal narrowing in a blood vessel or other tubular organ or structure.It is also sometimes called a stricture ....
). Occasionally, atheroma
Atheroma
In 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 the parent artery blocks the orifice
Orifice
An orifice is any opening, mouth, hole or vent, as of a pipe, plate, or a body.* Body orifice* Orifice plate* Calibrated orifice* Nozzle* Back Orifice-See also:* Choked flow* Needle valve* Venturi effect* Flow measurement...
of the penetrating artery (luminal atheroma), or atheroma involves the origin of the penetrating artery (junctional atheroma). Alternatively, hypoperfusion is believed to be the mechanism when there is stenosis of the penetrating artery. When no evidence of small vessel disease is found on histologic examination, an embolic cause is assumed, either artery-to-artery embolism
Embolism
In 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...
or cardioembolism. In one recent series, 25% of patients with clinical radiologically defined lacunes had a potential cardiac cause for their strokes.
Advanced age, chronic hypertension
Hypertension
Hypertension 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...
, smoking
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...
and diabetes mellitus
Diabetes mellitus
Diabetes 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...
are risk factors. It is unclear whether there is an association with alcohol consumption, elevated cholesterol, or history of prior stroke. Lacunar strokes may result from carotid artery
Carotid artery
Carotid artery can refer to:* Common carotid artery* External carotid artery* Internal carotid artery...
pathology or microemboli from the heart as in atrial fibrillation
Atrial fibrillation
Atrial 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...
. Patients often recover well, but if there is enough white matter disease from lacunar pathology, one can see a subcortical dementia such as Binswanger disease.
Signs & Symptoms
Each of the 5 classical lacunar syndromes has a relatively distinct symptom complex. Symptoms may occur suddenly, progressively, or in a fluctuating (e.g., the capsular warning syndrome) manner. Occasionally, cortical infarcts and intracranial hemorrhageIntracranial hemorrhage
An intracranial hemorrhage is a hemorrhage, or bleeding, within the skull.-Causes:Intracranial bleeding occurs when a blood vessel within the skull is ruptured or leaks. It can result from physical trauma or nontraumatic causes such as a ruptured aneurysm...
s can mimic lacunar infarcts, but true cortical infarct signs (such as aphasia, neglect, and visual field defects) are always absent. The 5 classic syndromes are as follows:
| Name | Location of infarct | Presentation |
|---|---|---|
| Pure motor stroke/hemiparesis (most common lacunar syndrome: 33-50%) | posterior limb of the internal capsule Internal capsule The internal capsule is an area of white matter in the brain that separates the caudate nucleus and the thalamus from the lenticular nucleus. The internal capsule contains both ascending and descending axons.... , or the basis pontis Basis pontis -Clinical significance:Infarction in this region can impair motor functioning.The basis pontis undergoes demyelination in the condition known as central pontine myelinolysis... |
It is marked by hemiparesis Hemiparesis Hemiparesis 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.... or hemiplegia Hemiplegia Hemiplegia /he.mə.pliː.dʒiə/ is total paralysis of the arm, leg, and trunk on the same side of the body. Hemiplegia is more severe than hemiparesis, wherein one half of the body has less marked weakness.... that typically affects the face, arm, or leg of one side. Dysarthria Dysarthria Dysarthria is a motor speech disorder resulting from neurological injury of the motor component of the motor-speech system and is characterized by poor articulation of phonemes... , dysphagia Dysphagia Dysphagia is the medical term for the symptom of difficulty in swallowing. Although classified under "symptoms and signs" in ICD-10, the term is sometimes used as a condition in its own right. Sufferers are sometimes unaware of their dysphagia.... , and transient sensory symptoms may also be present. |
| Ataxic hemiparesis (second most frequent lacunar syndrome) | posterior limb of the internal capsule Internal capsule The internal capsule is an area of white matter in the brain that separates the caudate nucleus and the thalamus from the lenticular nucleus. The internal capsule contains both ascending and descending axons.... , basis pontis Basis pontis -Clinical significance:Infarction in this region can impair motor functioning.The basis pontis undergoes demyelination in the condition known as central pontine myelinolysis... , and corona radiata Corona radiata In neuroanatomy, the corona radiata is a white matter sheet that continues caudally as the internal capsule and rostrally as the centrum semiovale. This sheet of axons contains both descending and ascending axons that carry nearly all of the neural traffic from and to the cerebral cortex... . |
It displays a combination of cerebellar and motor symptoms, including weakness and clumsiness, on the ipsilateral side of the body. It usually affects the leg more than it does the arm; hence, it is known also as homolateral ataxia and crural paresis. The onset of symptoms is often over hours or days. |
| Dysarthria/clumsy hand (sometimes considered a variant of ataxic hemiparesis, but usually still is classified as a separate lacunar syndrome) | basis pontis Basis pontis -Clinical significance:Infarction in this region can impair motor functioning.The basis pontis undergoes demyelination in the condition known as central pontine myelinolysis... |
The main symptoms are dysarthria and clumsiness (i.e., weakness) of the hand, which often are most prominent when the patient is writing. |
| Pure sensory stroke | contralateral thalamus Thalamus The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections... (VPL Ventral posterolateral nucleus The ventral posterolateral nucleus is a nucleus of the thalamus. Together with the ventral posteromedial nucleus , VPI and VMpo, it constitutes the ventral posterior nucleus.-Input and output:... ) |
Marked by persistent or transient numbness, tingling, pain, burning, or another unpleasant sensation on one side of the body. |
| Mixed sensorimotor stroke | thalamus Thalamus The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections... and adjacent posterior internal capsule Internal capsule The internal capsule is an area of white matter in the brain that separates the caudate nucleus and the thalamus from the lenticular nucleus. The internal capsule contains both ascending and descending axons.... |
This lacunar syndrome involves hemiparesis or hemiplegia with ipsilateral sensory impairment |
Silent lacunar infarction
A Silent lacunar infarction (SLI) is one type of silent strokeSilent stroke
A 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...
which usually shows no identifiable outward symptoms thus the term "silent". Individuals who suffer a SLI are often completely unaware they have suffered a stroke. This type of stroke often causes lesions in the surrounding brain tissue that are visibly detected via neuroimaging techniques such as MRI and computerized axial tomography (CAT scan). Silent strokes including silent lacunar infarctions have been shown to be much more common then previously thought, with an estimated prevalence rate of eleven million per year in the United States, approximately 10% of these silent strokes are silent lacunar infarctions. While dubbed "silent" due to the immediate lack of classic stroke symptoms SLIs can cause damage to the surrounding brain tissue (lesion
Lesion
A lesion is any abnormality in the tissue of an organism , usually caused by disease or trauma. Lesion is derived from the Latin word laesio which means injury.- Types :...
s) and can affect various aspects of a persons mood, personality and cognitive functioning
Cognitive functions
In some forms of psychological testing, particularly those related to the Myers-Briggs Type Indicator, the cognitive functions are defined as different ways of perceiving and judging the world...
. A SLI or any type of silent stroke places an individual at greater risk for future major stroke.
Treatment & Prognosis
Typically, tissue plasminogen activatorTissue plasminogen activator
Tissue plasminogen activator is a protein involved in the breakdown of blood clots. It is a serine protease found on endothelial cells, the cells that line the blood vessels. As an enzyme, it catalyzes the conversion of plasminogen to plasmin, the major enzyme responsible for clot breakdown...
may be administered within three hours of stroke onset if the patient is without contraindications (i.e. a bleeding diathesis such as recent major surgery or cancer with brain metastases). High dose aspirin
Aspirin
Aspirin , 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...
can be given within 48 hours. For long term prevention of recurrence, medical regimens are typically aimed towards correcting the underlying risk factors for lacunar infarcts such as hypertension, diabetes mellitus and cigarette smoking. Blood thinners such as heparin
Heparin
Heparin , 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 warfarin
Warfarin
Warfarin 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...
have shown no benefit over aspirin with regards to five year survival.
Patients who suffer lacunar strokes have a greater chance of surviving beyond thirty days (96%) than those with other types of stroke (85%), and better survival beyond a year (87% versus 65-70%). Between 70% and 80% are functionally independent at 1 year, compared with fewer than 50% otherwise.