CH10 by hcj


									CH10. Cerebral hemispheres and
                vascular supply

      By: Laurence Poliquin-Lasnier
                     R2 Neurology

• 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
• Venous drainage of the cerebral hemispheres
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
• 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
• 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
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

•   Lenticulostriate arteries
•   Anterior choroidal artery
•   Recurrent artery of Heubner
•   Thalamoperforator arteries
            Vascular territories of deep cerebral

Artery                From       Supply
Lenticulostriate      MCA        Basal ganglia, internal
Anterior choroidal    Internal   Globus pallidus, putamen,
                      carotid    thalamus, posterior limb
                                 internal capsule
Recurrent artery of   ACA        Head of the caudate, anterior
Heubner                          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

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

1. R homonymous hemianopia, alexia without
Clinical pearl: Alexia without agraphia

• Lesion in dominant (usually L) occipital
  cortex extending to the posterior corpus
• 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
     • Thalamoperforator branches of PCA
3- Ataxia hemiparesis

• Pure motor hemiparesis with ataxia on
  same side as weakness
• Location: Same as pure motor
• Vascular supply: Same as pure motor
4- Sensorimotor (thalamocapsular)

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

• Location:
  – Posterior limb internal capsule and either
    thalamic VPL or thalamic somatosensory
     • 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
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
• 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
• 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

• 3 main cerebral arteries
• 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

• 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)

• 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

• 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

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