Posterior cerebral artery syndromes

Homonymous hemianopia

Contralateral homonymous hemianopia is the typical symptom of PCA infarcts. Macular sparing may be observed because the cortical representation of the macula is broad and may receive dual arterial supply from the PCA and the MCA.

Alexia without agraphia (pure alexia)

Typically produced by damage to the left posterior fusiform gyrus or damage to the visual cortex and splenium of corpus callosum.

Very rarely the lesion might be on the right side.

Dejerine-Roussy syndrome

• Contralateral hemisensory loss (all modalities)
• Contralateral hemi-body pain which is usually burning or dysesthetic in quality and increases with touch or movement of the affected limb.

Produced by damage to the ventroposterolateral thalamus, often as a result of occlusion of penetrating PCA branches.

Anton-Babinski syndrome (visual anosognosia)

Up to 10% of patients with cortical blindness are unaware of their visual impairment and believe they can see normally.

Blindsight

Some patients with hemianopia or cortical blindness have some residual visual function that they are unaware of.

Agitation and delirium

PCA infarcts extending to the fusiform and lingual gyri sometimes result in a syndrome of hemianopia with agitated delirium.

Amnesia

Bilateral infarction of medial temporal lobe territories result in loss of ability to create new memories.

The amnesia can be severe and is almost always accompanied by visual and/or sensory deficits and often by decreased level of consciousness.

Hemineglect

Visual hemineglect is a complex phenomenon. The patients may show inattention to the contralateral hemifield even with the eyes pointed towards the normal hemispace and they may also show object-specific inattention to the contralateral side of objects even when those are placed in the normal visual field.

Neglect “dyslexia” is usually seen in patients with right-sided lesions. The patient fails to read words on the left side of the page, may start reading sentences omitting the leftmost part or make omission or substitution errors of the left part of words.

Hemineglect is more frequent in nondominant hemisphere lesions.

Hemianopia often masks the presence of visual hemineglect.

Bálint syndrome

Optic apraxia (loss of voluntary control of eye movements), optic ataxia, asimultagnosia (inability to direct a panoramic view) and visual inattention.

The syndrome can be produced by bilateral infarcts involving the posterior parietooccipital PCA-MCA border zone, often engaging the angular gyrus.

Weber syndrome

See Midbrain syndromes section

Claude Syndrome

See Midbrain syndromes section

Release hallucinations (Charles Bonnet syndrome)

• Restricted to the regions of the visual field with homonymous hemianopia.
• May be continuous or intermittent.
• Vary wildly in content from unformed, elementary to complex, detailed images.
• Their variability distinguishes them from the more stereotypical visual cortex seizures.

Pallinopsia (rare)

Visual perseveration in time. A recent image persists or recurs after the object has disappead from the field. The “afterimage” may persist or recur after minutes to even weeks.

Almost all patients have visual hemifield defects.

Cerebral polyopia (rare)

Visual perseveration in space. The image is perceived as duplicated or multiplicated and contrary to diplopia, it persists even with the eyes closed.

Visual distortions (rare)

• Micropsia is the illusion that objects are smaller than they really are.
• Macropsia is the illusion that objects are larger than they really are.
• Metamorphopsia is an illusion of object distortion.

Artery of Percheron syndrome

The artery of Percheron is a rare variant of the posterior cerebral circulation. A single arterial trunk arises from either PCA and supplies the paramedian thalami and the rostral midbrain bilaterally.

Symptoms and signs of artery of Percheron territory infarction may include:

• Consciousness impairment
• Altered mental state with agitation or obtundation
• Memory impairment
• Vertical gaze palsy
• Oculomotor disturbances
• Hemiplegia
• Hemisensory deficit
• Cerebellar ataxia
• Movement disorders