CH10. Cerebral hemispheres and vascular supply

By: Laurence Poliquin-Lasnier

R2 Neurology

Outline

• Review of the main functional cortical areas• Anterior circulation• Posterior circulation• Circle of Willis• Anatomy and vascular territories of:

a) ACA

b) MCA

c) PCA• Clinical syndromes of the 3 main cerebral

arteries• Venous drainage of the cerebral hemispheres• Clinical scenarios

Main functional areas of the brain

Anterior and posterior circulation

4 segments of internal carotid artery

1. Cervical segment

2. Petrous segment

3. Cavernous segment

4. Intracranial/supraclinoid segment

The anterior circulation: branches of the supraclinoid/intracranial carotid artery

• Mnemonic “OPAAM”

• O = Ophtalmic artery• P = Posterior communicating artery• A = Anterior choroidal artery• A = Anterior cerebral artery• M = Middle cerebral artery

The anterior circulation: branches of the intracranial carotid artery

The posterior circulation

Circle of Willis

3 main arteries

• Anterior cerebral artery (ACA)• Middle cerebral artery (MCA)• Posterior cerebral artery (PCA)

• ACA and MCA arise from the internal carotid artery

• PCA arise from the basilar artery

Circle of willis

Vascular territories of the 3 main cerebral arteries

• Vascular territories of the superficial cerebral structures

• Vascular territories of the deep cerebral structures

Superficial branches of ACA

Distribution of vascular supply

Superficial branches of the MCA

Distribution of vascular supply

Superficial branches of PCA

Distribution of vascular supply

Vascular territories of deep cerebral structures

• Lenticulostriate arteries• Anterior choroidal artery• Recurrent artery of Heubner• Thalamoperforator arteries

Vascular territories of deep cerebral structures

Artery From Supply

Lenticulostriate MCA Basal ganglia, internal capsule

Anterior choroidal Internal carotid

Globus pallidus, putamen, thalamus, posterior limb internal capsule

Recurrent artery of Heubner

ACA Head of the caudate, anterior putamen, globus pallidus, internal capsule

Thalamoperforator PCA Thalamus, posterior limb internal capsule

Lenticulostriate arteries

Superficial and deep vascular supply of the brain

Superficial and deep vascular supply of the brain

Clinical syndromes of the 3 main cerebral arteries

• MCA• ACA• PCA

Where is the lesion?

1. R face/arm UMN weakness, broca aphasia,+/- R face/arm cortical-type sensory loss

Distribution of vascular supply

Where is the lesion?

1. R pure motor hemiparesis (UMN)

2. R hemiplegia, R hemianesthesia, R homonymous hemianopsia, global aphasia, L gaze preference

Superficial and deep vascular supply of the brain

Where is the lesion?

1. R leg weakness (UMN), R leg cortical-type sensory loss, grasp, dishinibition

2. R homonymous hemianopia, alexia without agraphia

Clinical pearl: Alexia without agraphia

• Lesion in dominant (usually L) occipital cortex extending to the posterior corpus callosum

• Prevents processing of information in R visual field, including written material

• Information about L visual field is transmitted to R occipital lobe, but cannot cross to the left to the language areas by the corpus callosum lesion

Lacunar syndromes

• Lacune: small vessel infarct • Ressemble small lake or cavity when

examined on pathologic section

6 major lacunar syndromes:• Pure motor hemiparesis• Pure sensory stroke• Ataxic hemiparesis• Sensorimotor stroke• Dysarthria-clumsy hand syndrome• Basal ganglia lacune

1- Pure motor hemiparesis

• Unilateral face, arm, leg (UMN) weakness with dysarthria

• Location: – Posterior limb internal capsule (common)

• Lenticulostriate, anterior choroidal, thalamoperforator – Ventral pons (common)

• Ventral penetrating branches of basilar artery– Corona radiata

• Small MCA branches– Cerebral peduncle

• Small MCA branches

2- Pure sensory stroke

• Sensory loss to all primary modalities in the contralateral face and body

• Location: – Ventral posterior lateral nucleus (VPL) of

thalamus• Thalamoperforator branches of PCA

3- Ataxia hemiparesis

• Pure motor hemiparesis with ataxia on same side as weakness

• Location: Same as pure motor hemiparesis

• Vascular supply: Same as pure motor hemiparesis

4- Sensorimotor (thalamocapsular)

• Contralateral face/arm/leg sensory loss and weakness +/- dysarthria

• Location:– Posterior limb internal capsule and either

thalamic VPL or thalamic somatosensory radiations• Thalamoperforator arteries or

lenticulostriate arteries

5- Dysarthria-clumsy hand

• Facial weakness, dysarthria, dysphagia, and slight weakness and clumsiness of one hand

• Location: - Pons

- Pontine arteries- Genu of internal capsule

6- Basal ganglia lacune

• Hemiballismus or asymptomatic

• Locations:– Caudate, putamen, globus pallidus, or

subthalamic nucleus• Lenticulostriate, anterior choroidal,

thalamoperforator, or heubner’s arteries

Overview of venous drainage

• Superficial veins drain into the superior sagittal sinus and cavernous sinus

• Deep veins drain into great vein of Galen• Majority of veins ultimately drain to the internal

jugular veins• Superior sagittal sinus –> transverse sinuses -

>sigmoid sinus -> jugular foramen to become the internal jugular vein

• Cavernous sinus (int carotid artery, CN III-IV-V-VI) ->superior petrosal sinus -> transverse sinus

• Cavernous sinus -> inferior petrosal sinus ->internal jugular vein

Deep venous drainage

• Internal cerebral veins, basal veins of Rosenthal, and other veins ->great cerebral vein of Galen -> joined by inferior sagittal sinus –> to form straight sinus

• Confluence of sinus (torcular Herophili) = superior sagittal sinus + straight sinus + occipital sinus

• Confluence of sinus drained by transverse sinus

Overview of venous drainage

Deep venous drainage

Clinical scenario #1

• ID: 67yo woman• PMHx: HTN, PVD, smoker• HPI: after breakfast, she tried to stand up and

suddenly felt she could not support her weight -> fell -> 911

• Physical:• Alert & oriented• Unaware at times of L sided weakness• Language fluent• CN normal except minimally decreased L

nasolabial fold + mild dysarthria

Clinical scenario #1

• Motor: 5/5 except 1-2/5 in L leg prox and distal and 4/5 prox L arm

• L leg hyperreflexia, L Babinski• Sensory: inconsistent decreased response to

pinprick on L• Tactile extinction on L• One month later, partially recovered power,

but feels that her L arm is out of control, grasp onto things without her being aware and would have to use her R arm to release the grasp

• When distracted, can use both arms normally

Where is the lesion?

• R primary motor cortex foot area• Supplementary area given Alien hand

syndrome• Adjacent to R frontal and R parietal lobes

• R anterior cerebral artery occlusion

Clinical scenario #2

• ID: 52F• RFC: difficulty raising L arm• PMHx: HTN, smoker• HPI: noticed last night inability to raise L

arm to grasp cup of coffee. This mvt caused her L arm to flop up in the air and knock the coffee on the floor

• Physical:• R carotid bruit

Clinical scenario #2

• Decreased L arm power proximally (4-/5 deltoid, tricep 4/5, bicep 4+/5, 5/5 distally)

• Decreased L leg power proximally (iliopsoas 4/5) and rest 5/5

• L hyperreflexia arm and leg, L babinski• Sensory N• N FTN• Falls to the left on tandem gait

Where is the lesion?

• Unilateral proximal arm and leg weakness• Man in the barrel• Contralateral motor cortex proximal arm

and leg area, and trunk

• ACA-MCA watershed area 2ary decreased right carotid perfusion

Watershed areas

Conclusion

• 3 main cerebral arteries– ACA, MCA, PCA

• Anterior circulation composed of internal carotid artery that leads to ACA and MCA within the circle of willis

• Posterior circulation arises from vertebrobasilar system and leads to PCA within the circle of willis

Conclusion

• ACA supplies medial frontal and medial parietal lobes (sensorimotor cortex for lower extremities)

• PCA supplies the medial and inferior occipital and temporal lobes (primary visual cortex)

• MCA supplies entire lateral surface of the brain (face and arm sensorimotor regions + association cortex)

Conclusion

• MCA deep territory supplies internal capsule and most of basal ganglia

• ACA deep territory supplies anterior basal ganglia and internal capsule

• PCA deep territory supplies thalamus, midbrain, midbrain, posterior internal capsule

•

Conclusion

• Venous drainage occurs via superficial and deep cerebral veins

• Superficial veins drain into superior sagittal sinus and cavernous sinus

• Deep veins drain into great vein of Galen

• Ultimately all venous drainage reaches internal jugular vein mostly via transverse and sigmoid sinus