Module 2 Flashcards
what are the two main purposes of brain damage studies
- increases our understanding of the healthy brain
2. serves as a basis for the development of new treatments
what were professor P’s main symptoms
deafness in his right ear, balance problems, numbers on the right Side of his mouth, trouble swallowing, right tear duct was dry
what did prof P have
A tumor sitting on the right 8th cranial nerve (auditory vestibular)
what did prof P’s surgery leave him with
permanently deaf and without vestibular function on the right side of his face, hemifacial paralysis, blinking and tearing problems
what are the 5 causes of brain damage in the text
- tumors
- cerebrovascular disorders
- closed-head injuries
- infections of the brain
- genetic factors
what is a tumor, and what is another name for it?
Neoplasm, a mass of cells growing independently of the rest of the body
what is an meningioma, how many percent of brain tumours do these make up
20%, they grow between the meninges
what type of tumours are meningiomas? what does this mean? (3)
Encapsulated tumours - grow in their own membranes
- easy to spot in a CT
- Can only influence brain function by pressure
- almost always benign
what is a benign tumour
tumours that are surgically removable with little risk of further growth
what is an infiltrating tumour
those that grow diffusely through surrounding tissues
what are most infiltrating tumours, and what is this?
Malignant, which is to say they are difficult to remove or destroy, and any remaining cancerous tissue will continue to grow.
what are gliomas? are they mostly benign, malignant? encapsulated, infiltrating?
Brain tumours that develop from glial cells, they are infiltrating, malignant, and common
What is a metastatic tumour? what’s the percent of brain tumours they account for?
Any tumour that is grown from infiltrating cells and then carried to the brain by the blood stream.
10%
what is the most common origin of metastatic tumours?
the lungs
What are the chances of recovering from a cancer that has attacked two or more separate sites?
very low.
what are encapsulated tumours that grow on the VIII cranial nerve called?
Acoustic neuromas
what is a neuroma?
a tumour that grows on nerves or tracts
what is a stroke?
Sudden onset cerebrovascular disorders the cause brain damage
what are strokes highly implicated in? (3)
- 5th leading cause of death
- The major cause of neurological dysfunction
- leading cause of adult disability
what are the most common consequences of stroke? (4)
- amnesia
- aphasia
- paralysis
- coma
what is an infarct
the dead or dying tissue produced by a stroke
what is the tissue surrounding an infarct called? What will come of this tissue?
the penumbra
it may recover, or die, depending on a variety of fctors
what is the primary goal of post-stroke treatment?
to preserve the penumbra
what are the two main types of strokes?
- cerebral hemorrhage
2. cerebral ischemia
what is a cerebral hemorrhage
occurs when a cerebral blood vessel ruptures, blood seeps into surrounding neural tissue
what is a common cause of a cerebral hemorrhage?
what are these?
where do they tend to form, and why?
Aneurisms, which are pathological balloon like dilations
- form on the wall of can artery at point where its elasticity is defective
What are the two main pathways of aneurisms?
- congenital (present at birth)
2. result of exposure to vascular poisons / infection
what is cerebral ischemia
a disruption of the blood supply to an area of the brain
what are the three main causes of a ischemia?
- thrombosis
- embolism
- arteriosclerosis
what is thrombosis
a plug called a thrombus forms and blocks blood flow at the site of its formation.
could be formed of blood clots, fats, oils, air bubbles, tumours or any combination of the above
what is an embolism
a plug called an embolus is carried by blood from a larger vessel into a smaller one, where it becomes lodged
what is arteriosclerosis
walls of blood vessels thicken, narrowing channels, typically due to fat deposits, which eventually leads to the blockage of blood vessels
what is an angiogram?
X-ray of blood of lymph vessels, good for viewing strokes (particularly ischemia)
what are the two important properties of ischemia induced brain damage?
- Takes time to develop - substantial neuron loss begins to be noticeable a day or two later than the blockage first occurs
- not equally distributed throughout the brain, certain areas in the hippocampus are most susceptible
which neurotransmitter plays a role in ischemia? how?
glutamate (very excitatory).
- after bv becomes blocked, the blood deprived neurons become over-excited and release allot of glu.
- this in turn over activates glutamate receptor in post-synaptic neurons (these receptors are the NMDA receptors)
- lots of Na+ and Ca2+ ions enter post synaptic neurons, the excessive concentration of which affects the post synaptic neurons in two ways (later card)
what are the 2 ways excessive Ca2+ and Na+ ions in post synaptic neurons follow ischemia harm them?
- trigger further release of excessive glutamate, which furthers the toxic cascade
- trigger a series of internal reactions that ultimately kill these neurons
what is an implication of the discovery of the role of glutamate in strokes?
possibility of preventing stroke related brain damage by blocking the glutaminergic cascade, for example by using NMDA receptor antagonists is clinically effective, but need to be administered right after stroke, which makes them impractical
what are the 2 treatments that have been found to be effective in treating stroke?
- NMDA receptor antagonists (impractical, need to be administered right after the stroke.
- tissue plasminogen activator - breaks down blood clots
- if administered within 3-4 hours, leads to better recovery
what are the three symptoms that indicate that a blow to the head should be taken seriously/
- confusion
- sensorimotor disturbances
- loss of consciousness
what is a contusion
a closed head injury that involve damage to the cerebral circulatory system, which produces internal hemorrhagic
what does internal haemorrhaging lead to?
a hematoma, which is a localized collection of cloned blood in can organ or tissue (a bruise)
what do closed head injuries result from? where does the blood from such injuries usually accumulate
the brain coming into contact with the skull.
Typically in the subdural space, the space between the dura matter and arachnoid membrane, which can severely distort the surrounding neural tissue
what is a countercoup injury? are they common?
a contusion that occurs on the opposite side of the blow, and yes
what is a concussion
disturbance in consciousness following he’d trauma where there is no evidence of a contusion or other structural damage
what does the recent evidence surrounding concussions suggest?
their effects may last many years and the effects of repeated concussions can accumulate
what is CTE (give its full name, and symptoms)
Chronic traumatic encephalopathy.
the dementia and cerebral scarring observed in athletes and other people who have experienced repeated concussive or subconcussyve blows to the head
whaat did the Riley et all article conclude about the number of retired American football players with CTE
out of 35 studied, 34 had it
what are some common behavioural symptoms associated with CTE?
recklessness, gambling, addiction, violent outbursts
how do we diagnose CTE?
what is present in these cases?
autopsy, usually by finding aa proliferation of neurofibrillary tangles
what is a brain infection
invasion of the brain by micro organisms
what its he inflammation that results from a brain infection called
encephalitis
what are the two common types of brain infections
- bacterial
2. viral
what do bacterial infections typically cause (2)
- cerebral abscesses - pockets of puss in the brain
2. Meningitis - inflammation of the meninges
what is the percentage of adults that meningitis is fatal in?
30%
what treatments can be effective against bacterial infections>
penicillin and other antibiotics, can eliminate the infection but CANt reverse damage
what is syphilis?
- bacterial or viral?
- name of the associated psychotic illness
aa bacterial brain infection, passed to new hosts through contact with genital sores. tends to go dormant before becoming virulent and attacked many parts of the body, resulting in the brain in general paresis, a syndrome of mental illness and dementia
what are the two types of viral infections in the brain
- those with a particular affinity for neural tissue
2. those that attack neural tissue with no special affinity for it
What is rabies
a viral infection with a particular affinity for neural tissue, causing increased aggression to lead to biting which transmits it, it takes about aa month before it attacks the brain so we can vaccinate
what is the mumps / herpes examples of?
viruses that can attack the nervous system but have no affinity for it
what are we now beginning to suspect in regards to the role of viral infections in the ethology of disorders?
probably more than thought, hard to recognize because of the fact that they can lie dormant for so long.
what are the ways neurotoxic chemicals can enter general circulation? (3)
From the GI tract, the lungs, or the skin
which types of metals can be harmful to the nervous system?
heavy ones, like mercury
what is toxic psychosis
the permanent brain damage and associated psychological impairment caused by the accumulation of toxic chemicals in the brain
which types of psychotropic medications are neurotoxic?
Some older (and newer lol) antipsychotics which can cause tar dive dyskinesisa
what is tar dive dyskinesiaa
primary symptoms - involuntary smacking, sucking movement of the lips, thrusting and rolling of the tongue, lateral jaw movements, puffing of the cheeks
what are endogenous neurotoxins
those produced by the patients own body, typically antibodies that attack particular components of the NS, but also some excessive neurotransmitters (like in the case of ischemic stroke and glutamate)
are most genetic factors resulting in brain damage due to recessive or dominant genes?
recessive, easier to get passed along
what are the two reasons we haven’t been able to identify and discover effective treatments for the offending genes in all neuropsychological disorders? (2)
- numerous loci on human chromosomes have been assoc. with each disorder
- 90% of chromosomal loci involved in neuropsych disorders are not conventional protein coding genes, they were on poorly understood sections of genes
How does Apoptosis play a role in brain damage?
all of the other six causes of brain damage discussed in the text produce damage in part by activating apotpotic mechanisms
what was the early assumption about how cells died following brain damage? what is it now believed to be?
- thought to be purely necrotic
- now we know that if the damage isn’t incredibly severe, the cells will attempt to activate apoptosis
- not an either or situation, can show signs of both
explain the necrotic mechanism. how long does this take? what does it cause?
- damaged neurons swell and bark apart, beginning in the axons and dendrites, ending in the cell body
- few hours (fast)
- inflammation
explain the apoptotic mechanism. how long does this take? what does it cause?
- shrinkage of cell body, packaged into vesicles,
- slow (day or two)
- no inflammation, reduced damage to nearby tissues.
what its he primary symtopom of epilepsy? do all people who have these have epilepsy?
seizures, no, some one time seizures cn be triggered by exposure to convulsive toxins or high fevers
what is the diagnosis of epilepsy restricted to?
those who have seizures that are repeatedly generated by their own chronic brain dysfcuntion
what is the prevelance of epilepsy?
3.8% lifetime
are all seizures motor? what do we call motor seizures?
no, most are behavioural, cognitive, or emotional that are difficult to isolate from normal activity.
motor seizures are colvulsions
what are the 4 main etiological pathways of epilepsy?
- there are over 100 faulty genes,
- any of the causes of brain damage
- faults in inhibitory synaptses (GABAnergic), causing many neurons in a given area to fire in synchronous bursts
- inflammation
how do we diagnose epilepsy?
EEG, as epilepsy is associated with bursts of high amplitutde EEG spikes, often punctuating the scalp EEG of epileptics between seizures
what is an epileptic aura
peculiar psychological changes that occur just before a seizure
why are epileptic auras important? (2)
- provide clues about the location of the epileptic focus
2. warn patients of impending seizures
what are the two general categories of seizures?
- Focal
2. generalized
what is a focal seizure? Describe the pattern of neuronal firing.
a seizure that does not involve the entire brain.
focal epileptic neurons being to discharge together (synchronous, thus the EEG) in bursts, which tends to spread to other areas in the brain, but not to all areas of the brain in focal seizures.
what are the typical symptoms of focal seizures?
depend on the area they begin in, and where they spread, but they tend not to be accompanied by a total loss of consciousness or equilibrium, because they dont spread into the entire brain
what are the two major categories of focal seizures?
- simple partial
2. complex partial
what is aa simple partial seizure?
a focal seizure who’s symptoms are primarily (sensory v motor), often called Jacksonian seizures.
as the epileptic discharges spread throughout the sensory / motor brain areas, the symptoms spread systematically throughout the body
what is a complex partial seizure?
Often restricted to temporal lobes (thus called temporal lobe epilepsy), in which the patient engages in compulsive, repetitive and simple behaviours called automatisms, or more complex behaviours that seem normal
do patients tend to remember their complex partial seizures?
no, even though they are conscious during them
what is the percentage of cases of epilepsy that are complex-partial in nature?
bout half, the temporal lobes are particularly susceptible to epileptic discharge