VASCULAR SYSTEM AND ITS PATHOLOGIES
TYPES OF STROKE: The brain needs constant flow of blood to receive oxygen and nutrients, so that it can function properly. A stroke happens when blood flow to the brain is blocked or damaged in some way.
APHASIAS
CIRCLE OF WILLIS: Complex interconnectivity of arteries to continue blood flow if one path is blocked or narrowed.
ARTERIAL SYSTEM
EFFECTS OF CVA
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CORTICAL AREA ROLES IN LANG
HEMISPHERIC SPECIALIZATION
NON FLUENT
FLUENT
GLOBAL APHASIA: All language modalities are severely impaired; severe comp. and expressive deficits. People with Global aphasia can express through gestures and facial expressions; may only be able to express a single word or less; cannot follow simple questions or answer yes or no questions. Display extreme disorientation and confusion.
BROCA'S APHASIA: Caused by damage to the broca's area; results in language production errors. Common symptoms include: impaired fluency of spontaneous speech, phrase length is generally less than 5 words, agrammatic speech, number of nouns> number of functional words. Speech lacks prosody and reading out loud and writing is effortful and slow.
MIXED TRANSCORTICAL APHASIA: Aka isolated aphasia; Very similar to global aphasia where comprehension and expression are both impaired, although repetition is good.
TRANSCORTICAL MOTOR APHASIA: Agrammatism(lack of grammar) but repetition is still pretty good. More closely related to Broca's aphasia.
WERNICKE'S APHASIA: Caused by damage to the Wernicke's area, resulting in receptive or sensory aphasia (deficits are present with the comprehension of lang.
TRANSCORTICAL SENSORY APHASIA: More closely associated with a wernicke's type of aphasia. Paragrammatism meaning the patient will show some use of grammar but it is not typically an accurate use. Good with repetition, and has characteristics of echolalia.
ANOMIC APHASIA: Mildest form of aphasia; utterances are marked by word retrieval deficits. Show characteristics of perseveration, circulocation, and Paraphasis. Client will have long pauses between responses when trying to find a word.
CONDUCTION APHASIA: Caused by damage to the arcuate fasciculus. receptive and sensory aphasia. Intact language comprehension and expression. Selective lesions to the arcuate fasciculus are rare; generally lesions that affect this structure also affect cortical areas.
ISCHEMIC STROKE: Most common type of stroke. Happens in an artery where plaque build up has made the artery more narrow.
HEMARRHAGIC: Occurs when weakened artery breaks open and spills blood into the brain. This blocks flow. Also, the leaking blood puts pressure on the brain tissue, which can damage other cortical areas.
TRANSIENT ISCHEMIC ATTACK (TIA): A clot blocks the flow of blood to the brain. The clot will break up after a short period of time, and it usually doesn't cause permanent damage.
THROMBOTIC: Plaque can break apart and form blood clots that block the flow of blood.
EMBOLIC: A blood clot from somewhere in the body travels through the blood stream. If it reaches the arteries near or of the brain, it can block blood flow.
TWO PAIRS OF ARTERIES THAT SUPPLY THE BRAIN
ISCHEMIC CORE: Right where CVA occurs; Nerve cells have already died and function will not be regained.
PROCESS EXPLAINED
ISCHEMIC PENUMBRA: Area right outside of the ischemic core; nerve cells here may still be alive and may eventually start functioning with repair and regeneration if medical intervention is introduced in a timely manner.
EXCITOTOXICITY
INFLAMMATION AND APOPTOSIS: Cell death
REPAIR AND REGENERATION: takes place with intervention; healing.
ADVANTAGES: Provides a back up incase there is a problem with the flow of blood.
DISADVANTAGES: This area is prone to aneurysms.
CEREBELLAR ARTERIES
PONTINE ARTERIES: Run across the surface of the pons.
CEREBRAL ARTERIES
COMMUNCATING ARTERIES
INTERNAL CAROTID ARTERY: Divides into the ACA and the MCA. The internal carotid artery supplies the anterior portion of the brain.
AORTA
ANTERIOR CEREBRAL ARTERIES: Supplies blood to the frontal lobe, parietal lobe, basal ganglia, and corpus collosum.
MIDDLE CEREBRAL ARTERIES: Supplies blood to the Language cortexes, primary cortex, temporal lobe, broca's area, and wernicke's area.
POSTERIOR CEREBRAL ARTERIES: Supplies the posterior third of medial surface of the cerebrum, and the occipital lobe.
MIDDLE CEREBRAL ARTERY: Supplies the lateral surfaces of the cerebrum.
ANTERIOR CEREBRAL ARTERIES: Supplies the anterior 2/3 of the medial surface of the cortex, and the frontal pole.
POSTERIOR COMMUNICATING ARTERIES: The MCAs and the PCAs are connected to each other by this communicating artery.
ANTERIOR COMMUNICATING ARTERIES: The ACAs are connected to each other through this communicating artery.
HEMISPHERIC CONNECTION
Language areas are generally identified in the left hemisphere of the brain. Language is primarily processed in the dominant hemisphere.
LEFT HANDED PEOPLE: Often have significant bilateral representation of language and may show quicker language recovery following left hemisphere lesions.
CORPUS COLLOSUM: Language areas in the left and right hemispheres are connected by this. Even in cases of highly lateralized functional areas, info. must still pass to the non-dominant hemisphere.
ANOXIA: No oxygen at all to cell. Leads to tissue necrosis (cell death).
HYPOXIA: Nerve cells have partial loss of oxygen to the cell.
FACTORS THAT INCREASE STROKE LIKELIHOOD: tobacco use, physical activity, and high blood pressure.
PRIMARY AUDITORY AREA+ ASSOCIATION AREA/VISUAL PRIMARY AND ASSOCIATION AREAS (Depends on the stimulus): The sound of spoken language is perceived or the sight of a cue card is perceived.
WERNICKE'S AREA: Comprehends the words and applies meaning.
ARCUATE FASCICULUS: A subcortical bundle of white matter that connects the Wernicke's and Broca's areas. This connecting network allows is to produce words that make sense, understand what is said, and respond appropriately.
BROCA'S AREA: Production of language. formulates vocab, grammar, sentence structure.
PREMOTOR AREA AND SUPPLEMENTAL ASSOCIATION AREA: These areas aid in speech planning and timing. What goes where, when?
PRIMARY MOTOR CORTEX: Signals from premotor and association areas are then sent to muscles.
MUSCLES: Articulators for example
CHARACTERISTICS
CIRCULOCATIONS: Beating around the bush. For example;
Instead of saying "pen" they might say "the thing that you would use to write".
PERSEVERATIONS: When person is stuck on behaviors; may be stuck on something they already used to answer earlier in the conversation.
PARAPHASIS: Word and sound substitutions. For example;
WORD- client says "chair" instead of "sofa"
SOUND- client says "pan" instead of "fan".
MOST SEVERE TYPE OF APHASIA
CAUSE: Usually results from a large lesion involving both the Broca and wernicke areas.
Overlearned, familiar speech output is often easier EX: reciting the alphabet. Cueing improves performance. Language comprehension is intact and as a result patients are often frustrated with their inability to express their thoughts. Reading comprehension is generally intact.
Impaired naming, repetition and fluency with normal comprehension.
COMMON SYMPTOMS: Spontaneous speech with normal fluency and prosody, but speech is empty and meaningless with many paraphasia errors(inappropriate word substitutions at the sound level or the word level). Impaired naming and repetition
Patients often seem unaware of their deficit, behaving as though they are carrying out a normal conversation. Patients can sometimes follow simple commands relating to axial musculature.
EX: Close your eyes
Impaired comprehension, naming, and repetition with normal fluency.
COMMON SYMPTOMS: the inability to repeat words, paraphasic errors and impaired naming.
Impaired naming and repetition with normal comprehension and fluency.
ECHOLALIA: Repetition of words without being aware of what they are saying; blindly retrieving words from Wernicke's area. Usually repeated words are only 1-2 syllables.
Multi-step process
- Disruption of oxygen and glucose in creating ATP. ATP= cellular energy chemical.
- This lowers the production of ATP.
- ATP dependent ion pumps fail.
- This causes intracellular calcium to rise, which then triggers the release of glutamate.
- Neighbor neurons get excited and increase levels of ROS (Reactive Oxygen Species) and enzymes.
- Causes cell to break down which leads to tissue necrosis.
ANEURYSMS: Balloon-like structures that are formed on the arteries, and can burst and rupture the artery, causing a leakage of blood into the brain.
LEFT HEMISPHERE: The left hemisphere is dominant in > 95% of right handed people and >60-70% of left handed people.
RIGHT HEMISPHERE: Usually the non-dominant hemisphere. The non-dominant hemisphere contributes to the non-verbal flavor of language.
Lesions to the left hemisphere are more likely to cause language deficits.
SIGNIFICANT CONTRIBUTIONS: to language include the following:
Tone of voice
Prosody or melody of speech
Music perception
Imparting emotional significance to language
SPLITS INTO TWO SUBCLAVIAN ARTERIES
VERTEBRAL ARTERIES: Branch off of the subclavian arteries.
BASILAR ARTERY: The two vertebral arteries join together at the junction of the Pons and Medulla Oblongata to form this artery.
1 SUPPLIES THE SUPERIOR SURFACE
2 SUPPLY THE INFERIOR SURFACE
POSTERIOR CEREBRAL ARTEIRIES: Branch off of the basilar artery.
POSTERIOR INFERIOR CEREBELLAR ARTERY: Arises from the vertebral artery, just below the olives.
SUPERIOR CEREBELLAR ARTERY: Branches off from the Basilar artery at the junction of the pons and the cerebral peduncles.
ANTERIOR INFERIOR CEREBELLAR ARTERY: Arises from the caudal end of the Basilar artery (bottom end towards the heart).
OTHER CAUSES OF APHASIA
INFECTIONS: such as meningitis and encephalitis.
BRAIN INJURY: Head injury involving the frontal or temporal lobes
BRAIN TUMOR