3. Stroke is the fifth leading cause of death in the
USA and the second leading cause of death
worldwide.
The overall prevalence of stroke in the U.S. is
2.6% in adults over 20 years old.
Approximately 85% of these are ischemic
strokes, and over half of all ischemic strokes
occur in MCA territory
6. The MCA is the larger terminal branch of the
ICA.
The main stem varies in diameter from 2.4 mm-
4.6 mm and in length from 18 mm-25 mm.
5-17 penetrating lenticulostriate arteries branch
off this MCA trunk
The MCA runs first in the lateral cerebral fissure,
then posterosuperiorly on the insula; it divides
into branches distributed to this and the
adjacent lateral cerebral surface.
7. The surgical nomenclature identifies 4
subdivisions:
1. M1, from the termination of the ICA to the
bi-or trifurcation ( sphenoidal segment)
2. M2, the segment running in the lateral
(Sylvian) fissure (insular segment)
3. M3, coming out of the lateral fissure
(operator segment)
4. M4, the cortical portions.
8. Cortical branches supply:
1. The inferior frontal gyrus
2. The lateral orbital surface of the frontal lobe
3. The precentral, middle and inferior frontal
gyri
4. 2 parietal branches supply the postcentral
gyrus
5. The lower part of the superior parietal lobule
6. The whole inferior parietal lobule
7. 2 or 3 temporal branches supply the lateral
surface of the temporal lobe
9. Small central branches of the MCA
the lateral striate or lenticulostriate arteries
arise at its commencement and enter the
anterior perforated substance together with the
medial striate artery.
They supply the BG, i.e. the striatum, much of
the head and body of the caudate nucleus, and
large portions of the lenticular nucleus and of
the external and IC.
10.
11.
12.
13.
14.
15.
16.
17.
18. Anatomical variations of the MCA
The most frequent anatomical variations of the MCA are:
1) Duplication of the MCA (DMCA) (0.7 to 2.9% in autopsy studies
and 0.24 to 1.5% in angiographic studies ).The DMCA is classified
into two types, Type A and Type B. Type A: the duplication of the
MCA which separates from the ICA bifurcation, and Type B: the
blood vessel that arises from the ICA between the anterior
choroidal artery (AChA) and bifurcation of the ICA
2) Accessory MCA. an artery arising from the proximal A1 segment of
the ACA. The accessory MCA perfuses the territory of the orbito-
frontal branch or the perforating arteries . The incidence of
accessory MCA ranges in autopsy and angiographic studies from
0.3 to 4%
3) Fenestration of the MCA i.e., a bridged opening in the blood
vessel, in angiographic studies as 0.17–0.43% and in autopsy
studies from 0.02 to 1%
21. Occlusion of upper division of the MCA
1. hemiplegia, more severe in the face, hand,
and upper extremity, with relative sparing of
the lower extremity
2. hemisensory loss, usually including
decreased pinprick and position sense,
sometimes sparing the leg
3. conjugate eye deviation, with the eyes
resting toward the side of the brain lesion
22. 4. lesion in the left dominant hemisphere is accompanying
aphasia. Verbal output is sparse and patients do not do
what they are asked to do with either hand but they
follow whole body commands as turn over, sit, and stand.
comprehension of written material is poor. With time, a
pattern of Broca’s aphasia evolves (sparse, effortful
speech, poor pronunciation of syllables, and omission
of filler words). Comprehension of spoken language is
usually preserved.
5. infarcts in the right hemisphere; the patient often seem
unaware of their deficit (anosognosia) and may not admit
they are hemiplegic. Some patients are impersistent; they
perform requested tasks quickly, but fail to persevere and
terminate tasks prematurely. When asked to read,
patients often omit the left of the page or paragraph, and
do not heed people or objects to their left.
23.
24. Occlusion of the inferior division
1. No elementary motor or sensory abnormalities
2. visual field defect, either a hemianopia or an upper quadrantanopia
3. When the left hemisphere is involved, Wernicke-type aphasia( Speech is
fluent, and syllables are well pronounced. Patients use wrong or non-
existent words and what is said makes little sense. Comprehension and
repetition of spoken language are poor. There is sparing of written
comprehension )
4. When the right hemisphere is affected, patients draw and copy poorly,
and may have difficulty finding their way about or reading a map.
Patients with right temporal infarcts often have an agitated hyperactive
state resembling delirium tremens.
5. Behavioral abnormalities; Patients with Wernicke’s aphasia are
sometimes irascible, paranoid, and may become violent
Diagnosis of right inferior-trunk occlusion is sometimes difficult unless
patients are examined thoroughly. The key neurological findings are a left
visual-field defect and poor drawing and copying in an agitated person.
25.
26. Deep infarction
Obstruction of lenticulostriate branches leads to selective infarction within the basal
ganglia and internal capsule.
1. the lesions can be confused with lacunes, but are larger and often extend to the
inferior brain surface. Some have called these lesions giant lacunes.The preferred
term for these deep MCA lenticulostriate-territory lesions is striatocapsular
infarcts
2. Patients with stratiocapsular infarcts are invariably hemiparetic, but the
distribution of weakness in face, arm, and leg is variable.
3. Sensory loss is usually minor because the posterior portion of the internal
capsule is spared
4. When the lesion is in the left hemisphere, after a short period of temporary
mutism, speech is sparse and dysarthric, but repetition of spoken anguage is
preserved. Comprehension of spoken and writtenlanguage depends on the size
and anteroposterior extent of the lesion
5. When the right hemisphere is involved, there often is neglect of contralateral
visual and tactile stimuli, but this is usually more transient than with parietal
cortical infarction.
27.
28. Mainstem occlusion of the MCA
1) Severe paralysis, hemisensory loss, attentional
hemianopia, and conjugate eye deviation to the opposite
side
2) When the left hemisphere is involved, there is a global
aphasia
3) Right hemisphere lesions produce severe neglect,
anosognosia, disinterest or poor motivation, apathy, and
severe constructional apraxia
4) Brain edema with swelling of the infarcted hemisphere,
causing a midline shift and brain herniations, is an
important complication in patients with large MCA-
territory infarction. This complication is especially apt to
develop in young patients with large embolic MCA-
territory infarcts. Coma usually heralds a fatal outcome
29.
30.
31. Opercular syndrome
The opercular regions are in the facio-pharyngo-
glosso-masticatory area of the premotor- and
primary motor cortex
Clinical of opercular syndrome
1) Anarthria and voluntary bilateral facial,
pharyngeal, lingual and masticatory paralysis
2) He is able to close his eyes during sleep, to
yawn and to manifest emotional facial
mimicry
