Middle Cerebral Artery Syndromes

stroke

1. Middle Cerebral Artery Syndromes BY DR MOHAMMUD IBRAHEEM

2. Epidemiology

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

4. Yee Sien Ng, et al 2007

5. Anatomy of MCA

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: M1, from the termination of the ICA to the bi-or trifurcation ( sphenoidal segment) M2, the segment running in the lateral ( Sylvian ) fissure (insular segment) M3, coming out of the lateral fissure (operator segment) M4, the cortical portions.

8. Cortical branches supply: The inferior frontal gyrus The lateral orbital surface of the frontal lobe The precentral , middle and inferior frontal gyri 2 parietal branches supply the postcentral gyrus The lower part of the superior parietal lobule The whole inferior parietal lobule 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. Anatomical variations of the MCA The most frequent anatomical variations of the MCA are: 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 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% 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%

11. Syndromes of MCA occlusion

12. Occlusion of upper division of the MCA hemiplegia , more severe in the face , hand, and upper extremity, with relative sparing of the lower extremity hemisensory loss, usually including decreased pinprick and position sense, sometimes sparing the leg conjugate eye deviation, with the eyes resting toward the side of the brain lesion

13. 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. 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.

14. Occlusion of the inferior division No elementary motor or sensory abnormalities visual field defect, either a hemianopia or an upper quadrantanopia 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 ) 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 . 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.

15. Deep infarction Obstruction of lenticulostriate branches leads to selective infarction within the basal ganglia and internal capsule. 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 Patients with stratiocapsular infarcts are invariably hemiparetic , but the distribution of weakness in face, arm, and leg is variable. Sensory loss is usually minor because the posterior portion of the internal capsule is spared 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 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 .

16. Mainstem occlusion of the MCA Severe paralysis, hemisensory loss, attentional hemianopia , and conjugate eye deviation to the opposite side When the left hemisphere is involved, there is a global aphasia Right hemisphere lesions produce severe neglect , anosognosia , disinterest or poor motivation, apathy, and severe constructional apraxia 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

17. Opercular syndrome The opercular regions are in the facio - pharyngo - glosso -masticatory area of the premotor- and primary motor cortex Clinical of opercular syndrome Anarthria and voluntary bilateral facial, pharyngeal, lingual and masticatory paralysis He is able to close his eyes during sleep, to yawn and to manifest emotional facial mimicry

18. Thank you