Blood Supply and Drainage of Brain😊

• Note: Middle cerebral artery does not form the Circle of Willis.

• Labyrinthine artery: Branch of AICA

• Ophthalmic artery: 1st branch of ICA

• Internal carotid: main brain supply.

• Posterior cerebral artery: From basilar artery.

Brainstem Syndrome

Midbrain Syndromes

• Weber → Weakness

• Benedict → See Red blood (Red nucleus) → Bobbing head

• Nothnagel → walk north = Superiorly (SCP) → thalakarangi (Ataxia)

• Claude = Combo

• Perinaud → Puthiya naattil poyi
• Kannu thallipoi (Lid retraction)
• Vayal nokki ninnu (Loss of upgaze)
• Look here and there (Nystagmus)
• Light kannil adichu (Light acc dissociation)

• Weber Sx
• P1 PCA
• I/l down and out pupil → I/L 3rd nerve palsy
• C/L hemiplegia
• Crus cerebri involved ⇒
• so crossed hemiplegia.
• Affect Corticospinal pathway crossing;

• Benedict Sx
• I/L down and out pupil
• C/l hyperkinesis, chorea, tremor

• Claude Sx
• I/L down and out pupil
• C/l hemiataxia
• C/L hyperkinesis, chorea, tremor

Parinaud Sx / Dorsal midbrain syndrome

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• Cause
• Pineal gland tumor
• Compress Dorsal midbrain → tectum and colliculi
• Damage to posterior commisure

• Supranuclead vertical gaze disorder
• Loss of upgaze
• Convergence divergence nystagmus on attempted upgaze

• Collier sign - Lid retraction

• Downward occular deviation: Setting sun sign

• Pseudo-Argyll–Robertson pupil
• Accommodative paresis
• Mid-dilated pupils
• Light–near dissociation (Light accomodation dissociation)

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Pontine Syndromes

• Millard- Gubler Sx
• Dorsal pontine asthma
• Lesion in abducent fascicle
• Basilar/pontine artery involvement
• Features
• C/l hemiplegia + I/L CN 6 + 7
• I/L Lateral/ horizontal gaze palsy

• Foville Sx
• Ventral pontine asthma
• Lesion in abducens nucleus
• Features
• C/l hemiparesis + I/L CN 6 + 7 + 8 CN palsy
• I/L Lateral/ horizontal gaze palsy
• All - Fovall lost

• Raymond Sx
• C/l hemiplegia
• I/L CN 6 palsy
• I/L Lateral/ horizontal gaze palsy
• Common fabric Raymond - common 6 th N

Locked-in syndrome:

• Bilateral ventral pontine lesion (basilar artery occlusion).

• Seen in
• Osmotic demyelination syndrome
• Large basilar thrombosis.

• Features
• Quadriplegia, anarthria.
• Bilateral Babinski/long tract signs can occur.
• Preserved Normal respiration, consciousness and vertical eye movements
• (spared supranuclear pathways).

• Central pontine fibres appear white

Medial Medullary Sx. / Djerine Sx

• Vascular Supply -> Ant. spinal artery

• C/l hemiplegia

• I/L tongue deviation
• 12th CN
• Tongue deviation to I/L side on protrusion.

Lateral Medullary / Wallenburg Sx

• Vertebral artery > PICA

• Trigeminal sensory nucleus affected:
• I/L face sensory loss.

• Crossed hemianesthesia.

• Loss of pain, temp from c/l body
• Lateral spinothalamic

• Horner's

• Dysphagia, hoarseness, loss of gag
• Multiple CNs (5, 7, 8, 9, 10, 11) may be involved.
• 12 CN NOT involved (medial).

Lateral Pontine Lesion /Marie Fox

• Structures involved
• Descending corticospinal tract
• Spinothalamic tract

• Clinical features
• I/L facial nerve palsy → weakness of same side face
• C/L loss of pain & temperature → opposite side body (leg)

MR Angiography

• Visualizes brain circulation.

Features

• Occurs in the circle of Willis

Important

• M/c site: 
• Junction of Anterior communicating artery with ACA
• Compresses optic chiasma.

• Most common cranial nerve involved in unruptured or ruptured
• 3rd cranial nerve → ptosis

• M/c location of unruptured that results in 3rd nerve palsy:
• Posterior communicating artery
• Compresses oculomotor nerve

• Rupture leads to subarachnoid hemorrhage (SAH)

• Layer of blood vessel affected in patient
• Internal elastic lamina.

• Most common site of rupture
• If size is >8 mm
• Top of basilar artery.
• At origin of posterior cerebral artery
• Near origin of posterior communicating artery
• M/c rupture: 
• Apex of aneurysm

• Rarest location
• Vertebral artery.

• Rupture of the saccular aneurysm:
• Leads to subarachnoid hemorrhage.

 

• Brain Stem
• Comprises:
• upper midbrain
• middle pons
• lower medulla

• Ventricles and Associated Structures

Structure	Relation / Position
4th ventricle	• Triangular area between pons and cerebellum
Lateral ventricle	• Beneath corpus callosum; • Opens through foramen of Monro into 3rd ventricle
Mamillary body	• In front of midbrain
Colliculi	• Posterior part of midbrain
Pineal gland	• Beneath corpus callosum splenium; • Behind 3rd ventricle; • Posterosuperior to midbrain
Fornix	• White matter tract related to corpus callosum
Pituitary gland	• Adjacent to sphenoid sinus

Brainstem and Vasculature

• Vertebral arteries: Black areas surrounding medulla oblongata.

• Basilar artery: In front of pons.

• Temporal lobe: Inferior most lobe.

• Midbrain: Heart-shaped/mickey mouse-shaped.

• Mammillary body: In front of midbrain, shows hyperintensity.

• Wernicke's encephalopathy affects the mamillary body.

Brain Areas and Blood Supply

Applied Aspect

• ACA stroke:
• Causes C/L LL paralysis
• Incontinence.

• Cranial nerve 9 in a separate sheath

• Cranial nerve 10 and 11 in a common sheath (vagoaccessory complex)

• Sigmoid sinus and inferior petrosal sinus enter the jugular foramen
• Combine to form internal jugular vein



Relations	Content
Anteromedial	Inferior petrosal sinus
Posterolateral	Sigmoid sinus

• Between them: CN IX, X, XI

Dural Venous Sinus Thrombosis CT/MRI

• Plain CT → Dense clot sign
• Thrombus appears white

• CECT → Delta sign or Empty delta sign.
• In superior sagittal sinus thrombosis
• Accumulation or pooling of blood
• Hemorrhagic infarct
• Triangle (delta) area shows filling defect

• MRI → No Flow Void

Arachnoiditis

• Empty thecal sac sign is seen.
• Normally, thecal sac has black nerve roots.

• Mnemonic:
• Empty thekkan → Aere (Arachnoid) theeykkum ini
• Empty delta sign → D for D → Dural venous sinus → sagittal sinus thrombosis

• In arachnoiditis, inflammation/fibrosis pulls nerve roots to periphery.
• No nerve roots visible in thecal sac.

ICT ↑↑

ICT ↑↑ in children

• Copper beaten / silver beaten appearance

ICT ↑↑ in adults

• Empty sella sign

• Herniation of subarachnoid space into sella
• → Clinoid process erosion / dorsum sella erosion

• Leads to flattened pituitary gland against floor of sella

• Paired sinus

• Located on either side of the body of the sphenoid bone

Location

• Middle cranial fossa

• Sides of Sella turcica

• Extends:
• From superior orbital fissure to foramen lacerum
• From lesser wing of sphenoid to petrous temporal bone

Contents

• Content: ICA, CN 6

• Medial:
• Pituitary gland
• Sphenoidal air sinus / body of sphenoid

• Lateral wall:
• CN III
• CN IV
• V1
• V2

• Superior:
• Optic nerve & optic chiasma.

 

• Venous drainage of Face:
• Via deep facial vein → pterygoid venous plexus
• Via angular vein → superior ophthalmic vein
• Superior ophthalmic vein is valveless

• Area between Nasion and angles of lips.

• Infection can spread to cavernous sinus via valveless veins.

• Facial Vein
• Valveless
• allow bidirectional blood flow
• allow retrograde spread of infection from face to cavernous sinus

• Facial vein → Deep facial vein → Pterygoid venous plexus → Emissary vein → Cavernous sinus
• Most common route

• Facial vein → Angular vein → Superior ophthalmic vein → Cavernous sinus

• Meningioma (arachnoid origin) commonly along superior sagittal sinus

ICA rupture in cavernous sinus

• Carotidocavernous fistula

• Causes pulsatile proptosis

• due to its connection with superior orbital fissure

• CN VI injury → In cavernous sinus thrombosis