9 - Cortical Function Flashcards
What is the cause of an acute onset (seconds to minutes), focal problem?
Vascular (or epileptic)
What is the cause of an acute onset (seconds to minutes) diffuse problem?
Cardiac (or epileptic)
What is the cause of a subacute onset (hours-days) focal problem?
I’s: Infectious, Immune, Inflammatory, Infiltrative
What is the cause of a subacute onset (hours-days) diffuse problem?
Toxic-metabolic
What is the cause of a chronic onset (weeks-months) focal problem?
Mass lesion
What is the cause of a chronic onset (weeks-months) diffuse problem?
Degenerative
Metabolic
Genetic
When is alteration of consciousness a cortical problem?
Alteration of consciousness is usually NOT a cortical problem, unless there’s very broad diffuse damage to the cortex.
Anterior (front) damage to the cortex results in ______ problems, while posterior (back) damage results in _______ problems.
Front: action/motor
Back: perception/sensory
Describe the functions of the left and right side of the brain that could help you localize a cortical region?
Right: meaning of thing s(ie emotions tied to things, such as making you happy or sad)
Left: symbols, details (letters, syntax, music notation, math).
Describe the functions of the upper and lower parts of the brain that could help you localize a cortical region?
Upper: external environment (ie space, time, people). ANS here connects to PAG.
Lower: internal environment (ie feelings, memories, bodily functions). ANS here connects to hypothalamus.
What is delirium? What is dementia?
Delirium: acute inability to attend or process; awake and alert. (delirium is always acute; if it’s not acute it can’t be delirium).
Dementia: chronic progressive decline in cog functions such as memory, language, or exec funciton (always chronic)
Decsribe the level of consciousness of someone who’s in a coma?
Unconscious; no type of stiulation will wake them up; no resposne to the environement.
How does the level of consciousness of someone sleepy differ from someone who is stuporous?
Sleepy: brief stimulation required to maintain awake state; more awake than asleep.
Stupor: alertness severely impaired; on-going stimulation required to become awake; more asleep than awake.
What parts of the brain are associated with arounsal (increasing level of consciousness)?
The brainstem ascending reticular activating system sends info to bilateral thalami, which send info to bilateral cerebral hemispheres.
What is the function of the frontal lobe from anterior to posterior?
Goal setting
Motor plans
Motor execution
Language generation - Broca’s area (R is generating tone, L is for motor)
What do lesions of the primary motor cause? What does activation of the primary motor cortex cause?
Lesion (suc has stroke): contra deficit
Activation:
- seizure:clonic movements
- jacksonian march: seizure that spreads and “marches” frmo one region to the next
What are three speeds of progression for sortical problems? What is an example of each?
Fast: <1 sec - ischemic
Medium: many seconds - seizure
Slow: minutes - migraine
Localize the lesion causing this man’s symptoms?
L primary motor cortex lesion resulting in R sided paralysis
L frontal eye field problem as well, resulting in gaze to point to the ipsi side of the lesion (because FEFs help you look to the contra side)
What is the function of the prefrontal cortex?
“The world according to me”
Personality, executive function, sequencing, organization, abstraction, and problem solving.
Left side decodes the parts of the whole, and R side decodes meaning.
What is the function of the orbitofrontal cortex? What are the most common causes of lesions here and what do they result in?
Part of limbic system; involved in memory and emotions.
Common ways to get a lesion in this region: head trauma and meningioma.
Lesions cause socially inappropriate behavior.
What is the function of the medial frontal cortex? What results from a lesion here?
Resilience and adability, motivation, goal-directed behavior. Micturition inhibitory center.
Lesions result in akinetic mutism (not moving or speaking), abulia (absense of willpower), and incontinence (normal pressure hydrocephalus)
What is the function of the parietal lobe? What results from lesions here in the dominant and non-dominant lobe?
Primary somatosensory cortex: contra sensory loss.
Association cortex: loss of stereogenesis (abilty to recognize object by touch), graphesthesia
Non-donminant association cortex (R): neglect, apraxia (dressing)
What is the function of the nondominant parietal lobe in spatial attention
Non-dominant (Right side): drives attention to the world.
This is why a right sided lesion here causes L heineglect.
What is praxis? What is apraxia?
Praxis: ability to execute a learned skilled task
Apraxia: inability to perform a task despite good comprehension and ability to perform the component units of the task. Caused by non-dominant lesion of the association cortex (parietal lobe).
What can result in damage to the hippocampus?
Alzheimer’s disease: severe hippocampus atrophy usuallty where it begins
Herpes encephalitis
Scarring (Mesial temporal sclerosis) caused by seizures
What type of lesion is associated with a monocular vision problem? What about a binocular problem?
Monocular: anterior to chiasm
Binocular: retro-chiasmal
What type of lesions result in a horizontal vs. vertical meridian visual field defect?
Horizontal: anterior to chiasm
Vertical: posterior to chiasm
What does the amount of congriouos in a homonymous hemianopia tell you about the location of a lesion?
Less congruent (one side of visual field smaller than the other): more anterior
More congruent: closer to the occipital cortex
What are the different optic radiations?
Parietal optic radiations
Temporal optic radiations (meyers loop)
Describe the blood supply to the macula that can result in macular sparing?
Occipital pole region (macula) has dual supply.
PCA: primary contribution
MCA: collateral contribution
This means that an occlusion in one can be compensated for by the other and result in macular sparing.
What is a watershed infarct?
A watershed stroke or watershed infarct is defined as ischemia that is localized to the vulnerable border zones between the tissues supplied via the Anterior, Posterior and Middle Cerebral arteries.
What does a watershed infarct result in?
“Man in a barrel syndrome”: bilateral upper extremity paresis (paralysis) with intact motor functioning of the lower extremities, giving the appearance of being confined within a barrel.
A 78 yo suffers an ischemic stroke in the L middle cerebral artery. What symptoms would you except to find?
R hemiparesis, inability to calculate, inability to comprehend, gaze deviation to the L, inattention to objects in the R visual field.
An 82 yo suffers an ischemic stroke that leaves her with the following visual field deficit (see pic), what other symptoms would you expect to find?
Inability to comprehend.
What is Balint syndrome characterized by?
1. Asimultanagnosia: inability to perceive the visual field as a whole and only focuses on small portions of it
2. Optic ataxia: inability to point/reach for objects in visual fieldunder visual guidance
3. Ocular apraxia: inability to look at objects in VF using saccades
What causes Balint Syndrome?
Lesions of the bilateral occipital-parietal cortices - “where pathway”
MCA-PCA watershed infarcts
Alzheimers
