Middle cerebral artery syndrome
Encyclopedia
Middle cerebral artery syndrome is a condition whereby the blood supply from the middle cerebral artery
(MCA) is restricted, leading to a reduction of the function of the portions of the brain
supplied by that vessel: the lateral aspects of frontal, temporal and parietal lobes, the corona radiata
, globus pallidus
, caudate
and putamen
. The MCA is the most common site for the occurrence of ischemic stroke
[O'Sullivan, 2007].
Depending upon the location and severity of the occlusion, signs and symptoms may vary within the population affected with MCA syndrome. More distal blockages tend to produce milder deficits due to more extensive branching of the artery and less ischemic response. In contrast, the most proximal occlusions result in widespread effects that can lead to significant cerebral edema
, increased intracranial pressure
, loss of consciousness and could even be fatal
. In such occasions, mannitol (osmotic diuretic) or hypertonic saline are given to draw fluid out of the oedematus cerebrum to minimise secondary injury. Hypertonic saline is better than mannitol, as mannitol being a diuretic will decrease the mean arterial pressure and since cerebral perfusion is mean arterial pressure minus intracranial pressure, mannitol will also cause a decrease in cerebral perfusion.
Contralateral hemiparesis
and hemisensory loss of the face, upper and lower extremities is the most common presentation of MCA syndrome. Lower extremity function is more spared than that of the faciobrachial region. The majority of the primary motor and somatosensory cortices are supplied by the MCA and the cortical homunculus
can, therefore, be used to localize the defects more precisely.
Note: *faciobrachial deficits greater than that of the lower limb
Middle cerebral artery
-External links:*...
(MCA) is restricted, leading to a reduction of the function of the portions of the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
supplied by that vessel: the lateral aspects of frontal, temporal and parietal lobes, the 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...
, globus pallidus
Globus pallidus
The globus pallidus also known as paleostriatum, is a sub-cortical structure of the brain. Topographically, it is part of the telencephalon, but retains close functional ties with the subthalamus - both of which are part of the extrapyramidal motor system...
, caudate
Caudate
Caudate can refer to:* Caudate nucleus* Caudate lobe of liver* Cauda equina* Members of the Caudata order....
and 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...
. The MCA is the most common site for the occurrence of ischemic stroke
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...
[O'Sullivan, 2007].
Depending upon the location and severity of the occlusion, signs and symptoms may vary within the population affected with MCA syndrome. More distal blockages tend to produce milder deficits due to more extensive branching of the artery and less ischemic response. In contrast, the most proximal occlusions result in widespread effects that can lead to significant cerebral edema
Cerebral edema
Cerebral edema or cerebral œdema is an excess accumulation of water in the intracellular or extracellular spaces of the brain.-Vasogenic:Due to a breakdown of tight endothelial junctions which make up the blood-brain barrier...
, increased intracranial pressure
Intracranial pressure
Intracranial pressure is the pressure inside the skull and thus in the brain tissue and cerebrospinal fluid . The body has various mechanisms by which it keeps the ICP stable, with CSF pressures varying by about 1 mmHg in normal adults through shifts in production and absorption of CSF...
, loss of consciousness and could even be fatal
Fatal
Fatal may refer to:* Causing death* Fatal , an album by Hussein Fatal* Fatal Recordings, a feminist record label* Fatal, a rapper who collaborated with the band Therapy? on the song "Come and Die" from the Judgment Night film soundtrack...
. In such occasions, mannitol (osmotic diuretic) or hypertonic saline are given to draw fluid out of the oedematus cerebrum to minimise secondary injury. Hypertonic saline is better than mannitol, as mannitol being a diuretic will decrease the mean arterial pressure and since cerebral perfusion is mean arterial pressure minus intracranial pressure, mannitol will also cause a decrease in cerebral perfusion.
Contralateral 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....
and hemisensory loss of the face, upper and lower extremities is the most common presentation of MCA syndrome. Lower extremity function is more spared than that of the faciobrachial region. The majority of the primary motor and somatosensory cortices are supplied by the MCA and the cortical homunculus
Cortical homunculus
A cortical homunculus is a pictorial representation of the anatomical divisions of the primary motor cortex and the primary somatosensory cortex , i.e., the portion of the human brain directly responsible for the movement and exchange of sense and motor information of the rest of the body.There...
can, therefore, be used to localize the defects more precisely.
Signs and Symptoms
- HemiparesisHemiparesisHemiparesis 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 hemiplegiaHemiplegiaHemiplegia /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....
of the lower half of the contralateral face - HemiparesisHemiparesisHemiparesis 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 hemiplegiaHemiplegiaHemiplegia /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....
of the contralateral upper and lower extremities* - Sensory loss of the contralateral face, arm and leg*
- AtaxiaAtaxiaAtaxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...
of contralateral extremities* - Speech impairments/aphasiaAphasiaAphasia 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....
: Broca's, Wernicke's or Global aphasiaGlobal aphasiaGlobal aphasia is a type of aphasia that is commonly associated with a large lesion in the perisylvian area of the frontal, temporal and parietal lobes of the brain causing an almost total reduction of all aspects of spoken and written language. It involves a "left side blowout" which includes...
as a result of a dominant hemisphere lesion (usually the left brain) - Perceptual deficits: hemispatial neglectHemispatial neglectHemispatial neglect, also called hemiagnosia, hemineglect, unilateral neglect, spatial neglect, unilateral visual inattention, hemi-inattention or neglect syndrome is a neuropsychological condition in which, after damage to one hemisphere of the brain, a deficit in attention to and awareness of...
, anosognosiaAnosognosiaAnosognosia /æˌnɒsɒgˈnəʊsɪə/ is a condition in which a person who suffers disability seems unaware of the existence of his or her disability. Unlike denial, which is a defense mechanism, anosognosia is rooted in physiology...
, apraxiaApraxiaApraxia is a disorder caused by damage to specific areas of the cerebrum. Apraxia is characterized by loss of the ability to execute or carry out learned purposeful movements, despite having the desire and the physical ability to perform the movements...
, and spatial disorganization as a result of a non-dominant hemisphere lesion (usually the right brain) - Visual disorders: deviation conjugéeDeviation conjugéeDeviation conjugée or ipsilesional gaze shift is a medical sign indicating brain damage , wherein the pupils of the eye tend to move toward the side of the body where the lesion is located....
, a gaze preference towards the side of the lesion; contralateral homonymous hemianopsiaHomonymous hemianopsiaHemianopsia or hemianopia is visual field loss that respects the vertical midline, and usually affects both eyes, but can involve one eye only. Homonymous hemianopsia, or homonymous hemianopia occurs when there is hemianopic visual field loss on the same side of both eyes...
Note: *faciobrachial deficits greater than that of the lower limb