Brainstem😊& Brainstem Syndromes😍

Area Postrema

• In Medulla Oblangata

• Chemoreceptor trigger zone (CTZ)

• Highest Centre for vomiting

• No BBB → Circumventricular organ

 

• 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.

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)