Stroke Syndromes Flashcards
A focal neurologic deficit of vascular origin. Caused by an abrupt incidence of vascular insufficiency or bleeding into, or immediately adjacent to the brain
Stroke (Also called a cerebrovascular accident)
There is higher incidence and prevalence of stroke in the
Southeastern US
Is heteromodal (combined inputs from many modalities) and makes up the majority of the human cortex
Association cortex
Is the frontal cortex anterior to the motor, premotor, and limbic areas
Prefrontal cortex
What are the three main functions of the frontal association cortex?
Restraint, Initiative, and Order
The ability to inhibit inappropriate behaviors
Restraint
The motivation to pursue positive/productive activities
Initiative
The capacity to correctly perform sequencing tasks and cognitive operations
Order
Cause large changes in affect, mood, and personality
Frontal Lobe Lesions
Characterized by loss of restraint, inappropriate social behavior, loss of ambition and judgement and inability to plan for the future
Frontal Lobe Lesions
Functions in the coordination of complex aspects of human cognition and behavior. These require the integration of thought with emotion
Prefrontal cortex
Characterized by abulia, laughing at serious matters, and limited insight
Prefrontal cortex lesions
Responsible for making decisions about the future, planning, and maintaining focus
-Responsible for working memory
Dorsolateral Prefrontal cortex
Failure on Delayed Response Task This requires working memory and planning to retrieve the food after a period of time
Dorsolateral prefrontal lesions causing working memory deficits
Dorsolateral Prefrontal Cortex is important for planning a
Goal directed movement
Responsible for behavioral inhibition and empathy
Ventromedial/Orbitofrontal Prefrontal Cortex
Lesions cause inappropriate behaviors and patients do not respond to images of sad, happy, or angry faces
Lesions to Ventromedial/Orbitofrontal Prefrontal Cortex
An Example of an Orbitofrontal/Ventromedial Lesion is
-Most common type
Frontotemporal lobe dementia
Damage to the right parietal association cortex causes
Contralateral hemineglect syndrome
Ignorance of visual, somatosensory, or auditory stimuli, despite intact primary sensation.
-Drawing, reading and writing can reveal
Sensory neglect
Motor inattention to one side of the body, despite normal reflexes and strength: eyes deviated to side of lesion
Motor Neglect
Patients perceive their body as upright even when it is tilted to the side. Patients will also tend to gaze towards the lesion (away from the neglected side)
Motor Neglect
Lack of awareness of neglect. Lack of personal hygiene and grooming. Disownershipof affected part
Anosognosia
The process of selectively focusing on one aspect of the environment
Attention
The right parietal association cortex functions in
Attention
A right hemisphere lesion causes severe
Left neglect
A left hemisphere lesion causes minimal
Right neglect
Attentional processes are largely in the
Right Hemisphere
We have better attention mechanisms to the
Left
Extinction tests can uncover
Neglect
Patients with neglect will have normal responses to individual stimuli/commands, but demonstrate “extinction” on the
Neglected side
Each side tested alone patient will see/feel
Sensory extinction
Move each arm separately, and then both together to look for neglected arm or Allokinesia
Motor extinction
Moving the wrong arm to the command
Motor extinction
Stroke deficits arise from the
Subcortical structures and pathways
Medial portions of the frontal lobe and anterior parietal lobe are supplied by the
ACA
The regions supplied by the ACA have representations in
Lower limb motor and sensory function
Contralateral hemiparesis and sensory deficits are greater in the leg than the arm with
ACA stroke
What kind of aphasia do left sided ACA strokes cause?
Transcortical Motor Aphasia
The ACA deep branches are called the
Recurrent Arteries of Heubner
Supplies the anterior limb of the internal capsule and the caudate-putamen
Recurrent Arteries of Heubner (aka medial striate artery)
Characterized by contralateral hemichorea and contralateral weakness in the face and arm
Recurrent Arteries of Heubner strokes
Travels to the lateral cortex with several branches supplying subcortical regions
-Largest cerebral artery
Middle Cerebral Artery (MCA)
Deep penetrating “lenticulostriate” vessels supply the
Internal Capsule and Basal Ganglia
Prone to narrowing, particularly in patients with longstanding hypertension
Lenticulostriate arteries
Lenticulostriate arteries are common sites of lacunar infarct. This causes
Contralateral hemiplegia (pure motor hemiparesis) and possibly basal ganglia signs
Small lenticulostriateinfarcts may only affect
Ascending or descending pathways
In the posterior limb of the internal capsule, motor pathways (FAL) are anatomically separate from somatosensory pathways (fal) with motor pathways being
Anterior to Somatosensory
Lesions of the posterior limb of the internal capsule causes
Pure motor hemiparesis
These lesions to the posterior limb of the internal capsule are from one of three arteries. What are they?
- ) Anterior choroidal artery
- ) Lenticulostriate artery
- ) Branch of PCA
Usually supplies the region anterior to the central sulcus
Superior division of MCA
Supplies the region posterior to central sulcus together wit temporal regions
Inferior divisions of MCA
Causes contralateral UMN paralysis with upper limb deficits being greater than lower limb and the face
Superior divisions of MCA
Strokes in the superior divisions of MCA affect the
Motor Cortex
What do we see in the gaze of a patient with infarct in superior divisions of MCA?
Horizontal gaze to opposite side
What other deficits do we see in a superior division MCA infarct if it is on the
- ) Left
- ) Right
- ) Speech motor
2. ) Attention
An infarct to the inferior divisions of the MCA affects the
Sensory cortex (sensory loss is greater to upper limbs than lower and face)
What other deficits do we see in a inferior division MCA infarct if it is on the
- ) Left
- ) Right
- ) Speech sensory
2. ) Attention
With an inferior division of MCA infarct, we also see losses in
Visual field
Supplies visual radiations
Inferior divisions of MCA
Causes severe sensorimotor deficit in the contralateral body. (pre-and post-central gyri and internal capsule)
MCA stem stroke
Transient paralysis of horizontal gaze to the opposite side, with gaze preference towards the side of the lesion. (frontal eye field)
MCA stem stroke
If the MCA stem stroke is on the left side, we see
Global aphasia
If the MCA stem stroke is on the right side, we see
Neglect
Confusion-agitation from temporal lobe damage can occur with
MCA stem stoke
Pure motor hemiparesis from a lesion in the internal capsule, ventral pons, or cerebral crus is an example of
Subcortical lesion
Motor paresis and associated cortical signs from a lesion in the cortex is an axample of a
Cortical lesion
A deep branch from the internal carotid artery
Anterior Choroidal Artery
The anterior choroidal artery supplies the
Optic Tract and Internal Capsule
Characterized by contralateral homonymous hemianopsia and contralateral hemiplegia
Anterior choroidal artery syndrome
Symptom of anterior choroidal artery syndrome due to lesion to the optic tract
Contralateral homonymous hemianopsia
Supplies midbrain, thalamus, medial temporal and occipital lobe
Posterior Cerebral Artery
Left-sided PCA strokes cause
Transcortical sensory aphasia
Inability to read because the information from the left visual field cannot cross into the language areas (for interpretation of written language)
Alexia
Patients can write, because language and hand movements are intact, but cannot read what they write with
-Caused by PCA infarct
Alexia
Deep or stem strokes can produce contralateral
Hemianesthesia
Deep or stem PCA strokes may produce
Central pain syndrome
5-10% of all strokes are
Watershed infarcts
Cause “Man in a barrel” syndrome with sensory and motor loss of the proximal upper limbs, but little effect on the legs
MCA-ACA watershed infarcts
Which type of aphasia are caused by ACA-MCA watershed infarcts?
Transcortical motor aphasia
Which type of aphasia is caused by MCA-PCA infarcts?
Transcortical sensory aphasia
Neurons shut down, but may be restored when cerebral blood flow drops below
20mL/100g/min
Tissue necrosis (infarct) is seen when cerebral blood flow drops below
10mL/100g/min
Blood clot forms usually at site of atherosclerosic plaque, causing occlusion
-High risk factor in persons with cerebrovascular disease
Thrombus
A piece of material (usually blood) that lodges in a cerebral blood vessel.
-Commonly caused by atrial fibrillation
Embolus
An angular gyrus lesion causing agraphia and/or alexia with mild aphasia
Gerstmann syndrome
Causes acalculia and right-left confusion, finger agnosia -“touch your right ear with your left thumb”
Gerstmann syndrome
Disconnection of right hemisphere vision from left hemisphere language
-Word blindness
Alexia without Agraphia