Posterior cerebral artery syndrome
Encyclopedia
Posterior cerebral artery syndrome is a condition whereby the blood supply from the posterior cerebral artery
(PCA) is restricted, leading to a reduction of the function of the portions of the brain
supplied by that vessel: the occipital lobe
, the inferomedial temporal lobe
, a large portion of the thalamus
, and the upper brainstem and midbrain. [O'Sullivan, 2007].
Depending upon the location and severity of the occlusion, signs and symptoms may vary within the population affected with PCA syndrome. Blockages of the proximal portion of the vessel produce only minor deficits due to the collateral blood flow from the opposite hemisphere via the posterior communicating artery
. In contrast, distal occlusions result in more serious complications. Visual deficits, such as agnosia
, prosopagnosia
or cortical blindness
(with bilateral infarcts) may be a product of ischemic damage to occipital lobe
. Occlusions of the branches of the PCA that supply the thalamus can result in central post-stroke pain and lesions to the subthalamic branches can produce “a wide variety of deficits”.
Central Territory Lesions
Posterior cerebral artery
-External links: - Posterior Cerebral Artery Stroke* at strokecenter.org* at State University of New York Upstate Medical University* at psyweb.com* at neuropat.dote.hu...
(PCA) is restricted, leading to a reduction of the function of the portions of the brain
Brain
The brain is the center of the nervous system in all vertebrate and most invertebrate animals—only a few primitive invertebrates such as sponges, jellyfish, sea squirts and starfishes do not have one. It is located in the head, usually close to primary sensory apparatus such as vision, hearing,...
supplied by that vessel: the occipital lobe
Occipital lobe
The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1...
, the inferomedial temporal lobe
Temporal lobe
The temporal lobe is a region of the cerebral cortex that is located beneath the Sylvian fissure on both cerebral hemispheres of the mammalian brain....
, a large portion of the thalamus
Thalamus
The thalamus is a midline paired symmetrical structure within the brains of vertebrates, including humans. It is situated between the cerebral cortex and midbrain, both in terms of location and neurological connections...
, and the upper brainstem and midbrain. [O'Sullivan, 2007].
Depending upon the location and severity of the occlusion, signs and symptoms may vary within the population affected with PCA syndrome. Blockages of the proximal portion of the vessel produce only minor deficits due to the collateral blood flow from the opposite hemisphere via the posterior communicating artery
Posterior communicating artery
In human anatomy, the posterior communicating artery is one of a pair of right-sided and left-sided blood vessels in the circle of Willis. It connects the three cerebral arteries of the same side. Anteriorly, it connects to the internal carotid artery prior the terminal bifurcation of the ICA...
. In contrast, distal occlusions result in more serious complications. Visual deficits, such as agnosia
Agnosia
Agnosia is a loss of ability to recognize objects, persons, sounds, shapes, or smells while the specific sense is not defective nor is there any significant memory loss...
, prosopagnosia
Prosopagnosia
Prosopagnosia is a disorder of face perception where the ability to recognize faces is impaired, while the ability to recognize other objects may be relatively intact...
or cortical blindness
Cortical blindness
Cortical blindness is the total or partial loss of vision in a normal-appearing eye caused by damage to the visual area in the brain's occipital cortex. This damage is most often caused by loss of blood flow to the occipital cortex from either unilateral or bilateral posterior cerebral artery...
(with bilateral infarcts) may be a product of ischemic damage to occipital lobe
Occipital lobe
The occipital lobe is the visual processing center of the mammalian brain containing most of the anatomical region of the visual cortex. The primary visual cortex is Brodmann area 17, commonly called V1...
. Occlusions of the branches of the PCA that supply the thalamus can result in central post-stroke pain and lesions to the subthalamic branches can produce “a wide variety of deficits”.
Signs and Symptoms
Peripheral Territory Lesions- Contralateral homonymous hemianopsiaHomonymous hemianopsiaHemianopsia or hemianopia is visual field loss that respects the vertical midline, and usually affects both eyes, but can involve one eye only. Homonymous hemianopsia, or homonymous hemianopia occurs when there is hemianopic visual field loss on the same side of both eyes...
- cortical blindnessCortical blindnessCortical blindness is the total or partial loss of vision in a normal-appearing eye caused by damage to the visual area in the brain's occipital cortex. This damage is most often caused by loss of blood flow to the occipital cortex from either unilateral or bilateral posterior cerebral artery...
with bilateral involvement of the occipital lobe branches - visual agnosiaVisual agnosiaVisual agnosia is the inability of the brain to make sense of or make use of some part of otherwise normal visual stimulus and is typified by the inability to recognize familiar objects or faces...
- prosopagnosiaProsopagnosiaProsopagnosia is a disorder of face perception where the ability to recognize faces is impaired, while the ability to recognize other objects may be relatively intact...
- dyslexiaDyslexiaDyslexia is a very broad term defining a learning disability that impairs a person's fluency or comprehension accuracy in being able to read, and which can manifest itself as a difficulty with phonological awareness, phonological decoding, orthographic coding, auditory short-term memory, or rapid...
, anomia, color naming and discrimination problems - memory defect
- topographic disorientation
Central Territory Lesions
- central post-stroke (thalamic) pain: spontaneous pain, dysesthesias and sensory impairments
- involuntary movements: chorea, intention tremorIntention tremorIntention tremor, also known as cerebellar tremor, is a dyskinetic disorder characterized by a broad, course, and low frequency tremor. The amplitude of an intention tremor increases as an extremity approaches the endpoint of deliberate and visually guided movement...
, hemiballismusHemiballismusHemiballismus is a very rare movement disorder. It is 500 times rarer than Parkinson's disease. Its effects can sometimes be severe enough to prevent patients from being able to perform daily functions. It is usually associated with structural brain lesions but can occur with metabolic abnormalities... - contralateral hemiplegiaHemiplegiaHemiplegia /he.mə.pliː.dʒiə/ is total paralysis of the arm, leg, and trunk on the same side of the body. Hemiplegia is more severe than hemiparesis, wherein one half of the body has less marked weakness....
- Weber’s syndrome: occulomotor nerve palsy
- Bálint's syndromeBalint's syndromeBálint's syndrome is an uncommon and incompletely understood triad of severe neuropsychological impairments: inability to perceive the visual field as a whole , difficulty in fixating the eyes , and inability to move the hand to a specific object by using vision...
: loss of voluntary eye movements optic ataxiaAtaxiaAtaxia is a neurological sign and symptom that consists of gross lack of coordination of muscle movements. Ataxia is a non-specific clinical manifestation implying dysfunction of the parts of the nervous system that coordinate movement, such as the cerebellum...
, asimultagnosia (inability to understand visual objects)