Brain stem vascular lesions


By Dr Rabia Shafique

Brain stem vascular lesions

Occlusion of the anterior spinal artery causes medial medullary syndrome, presenting with inferior alternating hemiplegia.

Ipsilateral paralysis of tongue.

Contralateral hemiplegia.


Contralateral sensory deficits.

Occlusion of the posterior inferior cerebelllar artery causes lateral medullary syndrome featured

Contralateral hemianaesthesia of the body below the head.

Ipsilateral hemianaesthesia of the face.

Cerebellar dysfunction.

Speech and swallowing disorders.

Horners syndrome.

Occlusion of the paramedian branches of the basilar arteries causes middle alternating hemiplegia.

Contralateral hemiplegia.

Medial deviation of the eyeball.

Obstruction of the short circumferential arteries from the basilar artery cause

Ipsilateral cerebellar dysfunction

Autonomic disturbances

Contralateral hemianaesthesia

Occlusion of the mesencephalic branch of the posterior cerebral artery causes Weber’s syndrome

Contralateral hemiplegia

Ipsilateral lateral deviation of the eyeball

Cerebral Cortical Vascular Lesions

Occlusion of the anterior choroidal artery causes a triad of:

Contralateral hemiplegia


Hemi hyperacusis

Occlusion of anterior cerebral arteries may cause

Contralateral hemiplegia

Contralateral hemianaesthesia ( both mainly affect the lower limb)


Personality changes

Occlusion of the calcarine artery causes homonymous hemianopia with macular sparing (Tunnel vison)

Occlusion of the middle cerebral artery near the origin of its cortical branches causes

Contralateral hemiplegia , most marked in the upper extremity and face.

Contralateral loss of position sense and discriminatory touch.

Global aphasia if its on the dominant side.

Partial deafness.

Components of the BBB

Tight junctions between the capillary endothelial cells

Continuous homogenous basement membrane

Numerous astrocytic processes

Parts devoid of Blood Brain Barrier – circumventircular organs (CVO).

The pineal body

The subcommissural organ

The subfornical organ

The organum vasculosum of the lamina terminalis (supra-optic crest)

The median eminence

The neurohypophysis

The area postrema

Formation of Circle of Willis

This is the communication between vessels about the interpeduncular fossa.

It encircles the optic chiasma, tuber cinereum and interpeduncular region.

Formed by these arteries:

Posterior cerebral

Internal carotid

Posterior communicating

Middle cerebral

Anterior cerebral

Anterior communicating

The Internal Carotid Artery

Summary of the branches

Hypophyseal branches to the hypophysis cerebri

Ophthalmic artery

Posterior communicating artery

Anterior choroidal artery

Middle cerebral artery

Anterior cerebral artery


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