10- Brain Damage and Neuroplasticity

1. Brain tumors

2. Cerebrovascular disorders

3. Closed-head injuries

4. Infections of the brain

5. Neurotoxins

6. Genetic factors

Causes of the brain damage

tumor/neoplasm

mass of cells that grows independently of the rest of the body

meningiomas

about 20% of tumors in the human brain are

meningiomas

tumors that grow between the meninges

meninges

the three membranes that cover the CNS

Encapsulated tumors

all meningiomas are

Encapsulated tumors

tumors that grow within their own membrane

Benign tumors

tumors that are surgically remov-

able with little risk of further growth in the body

Infiltrating tumors

most brain tumors are

Infiltrating tumors

are those that grow diffusely through surrounding tissue.

Malignant tumors

it is difficult to remove or destroy them completely, and

any cancerous tissue that remains after surgery continues

to grow

Gliomas

brain tumors that develop from glial

cells

Metastatic tumors

They grow from infiltrating cells that are car-

ried to the brain by the bloodstream from some other part

of the body

Metastasis

refers to the transmission of disease from one

organ to another

Lungs

Many metastatic brain tumors originate as cancers of the -

Acoustic neuromas

Encapsulated tumors that grow on cranial nerve VIII are referred to as -

neuromas

are tumors that

grow on nerves or tracts

Strokes

are sudden-onset cerebrovascular disorders that

cause brain damage.

Strokes

common consequences are amne-

sia, aphasia (language difficulties), paralysis, and coma

Infarct

The area of dead or dying tissue produced by a stroke

Penumbra

Surrounding the infarct is a dysfunctional area

Save the penumbra

The primary goal of treatment following

stroke is to -

1. Cerebral hemorrhage

2. Cerebral ischemia

major types of stroke

Cerebral hemorrhage

bleeding in the brain

Cerebral hemorrhage

occurs when a cerebral blood vessel rup-

tures and blood seeps into the surrounding neural tissue

and damages it

intracerebral hemorrhage

Bursting aneurysms are a common cause

of -

Aneurysm

pathological balloonlike dilation that forms in the wall of an artery

at a point where the elasticity of the artery wall is defective

Cerebral ischemia

disruption of the blood supply to an area of the brain

1. thrombosis

2. embolism

3. arteriosclerosis

three main causes of cerebral ischemias

Thrombosis

a plug

is formed and blocks blood flow at the site of its formation.

Thrombus

may be composed of a blood clot, fat, oil, an air

bubble, tumor cells, or any combination thereof

Embolism

the plug is carried by the blood from a larger vessel, where it

was formed, to a smaller one, where it becomes lodged

Thrombus

plug in thrombosis

Embolus

plus in embolism

Arteriosclerosis

the walls of blood vessels thicken and

the channels narrow, usually as the result of fat deposits;

this narrowing can eventually lead to complete blockage of

the blood vessels.

Glutamate

the most prevalent excitatory neurotransmitter plays a major role in ischemia-induced brain damage

NMDA (N-methyl-D-aspartate) receptors

Glutamate overactivates its receptors, especially - leading to an influx of Na+ and Ca2+

Tissue plasminogen activator

a drug that breaks down blood clots soon after the onset of ischemic stroke can lead to better recovery

Closed-head injuries

Brain injuries due to blows that do not

penetrate the skull

Contusions

closed head injuries that

involve damage to the cerebral circulatory

system

Hematoma

localized collection of clotted blood in an organ or tissue, aka bruise

Subdural space

blood from closed-head injuries can accumulate in the -, the space between the dura mater and arachnoid membrane, and severely distort the surrounding neural tissue

Contrecoup injuries

contusions

are often on the side of the brain

opposite to the blow

Concussion

when there is disturbance

of consciousness following a blow to the

head and no evidence of structural

damage

Chronic traumatic encephalopathy (CTE)

is the dementia and cerebral scarring observed in boxers, rugby players, American football players, and other individuals who hace experienced repeated concussive, or even subconcussive blows to the head

Dementia

general intellectual deterioration

Punch-drunk syndrome

While there is no apparent brain damage

with a single concussion, multiple

concussions may result in a dementia

referred to as -

Brain infection

invasion of the brain by microorganisms

Encephalitis

the resulting

inflammation of the brain by an

invasion of microorganisms

1. Bacterial infections

2. Viral infections

two common types of brain infections

Cerebral abscesses

When bacteri infect the brain, they often lead to -, pockets

of pus in the brain

Meningitis

Bacteria are also the major cause of -, the inflammation of the meninges

Syphillis

the - bacteria are passed from infected to noninfected individuals through contact with genital sores

General paresis

the syndrome of mental illness and dementia that results from a syphilitic infection is called -

Rabies

transmitted through the bite of a rabid animal, is a well-known example of a virus that has a particular affinity for the nervous system

Mumps and herpes

common examples of viruses that can attack the nervous system but have no special affinity for it

Neurotoxins

May enter general circulation from the GI tract or lungs, or through the skin

Toxic psychosis

chronic insanity produced by a neurotoxin

The Mad Hatter

hat makers often had toxic psychosis due to

mercury exposure

Crackpot

referred to the toxic psychosis observed in people who steeped their tea in cracked ceramic pots with lead cores

Tardive dyskinesia (TD)

Some antipsychotic drugs produce a motor disorder called

Tardive dyskinesia (TD)

involuntary smacking and sucking movements of the lips, thrusting and rolling of the tongue, lateral jaw movements, and puffing of the cheeks

Endogenous

Some neurotoxins are produced by the patient’s own body

recessive genes

Most neuropsychological

diseases of genetic origin are

associated with -

Down syndrome

0.15% of births, probability

increases with advancing

maternal age

Chromosome 21

The genetic accident associated with Down syndrome occurs in the mother during ovulation when an extra - is created in the egg

Apoptosis

All six causes of brain

damage produce damage,

in part, by activating -

Epilepsy

Primary symptom is seizures, but not

all who have seizures have -

Epilepsy

have seizures generated by their own brain dysfunction

Convulsions

motor seizures

Clonus

tremors

Tonus

rigidity

Electroencephalography

Diagnosis of epilepsy rests heavily on evidence from -

Epileptic auras

Psychological changes just before a seizure

Focal seizure

seizure that does not involve the entire brain

Simple partial seizure

Symptoms are primarily sensory or motor or both

Jacksonian seizures

simple partial seizures are sometimes called - after the famous 19th century neurologist

Hughlings Jackson

the famous 19th century neurologist

Complex partial seizures

Often restricted to the temporal lobes

temporal lobe epilepsy

Those who experience complex partial seizures are often said to have -

automatisms

Patient engages in compulsive and repetitive simple behaviors called - in complex partial seizures

Generalized seizures

seizures that involve the entire brain

Tonic-clonic-seizure

Loss of consciousness and equilibrium and a violent tonic-clonic convulsions

tonic-clonic convulsions

convulsions involving both tonus and clonus

Tonic-clonic convulsion

tongue biting, urinary incontinence, and cyanosis

Cyanosis

turning blue from excessive extraction of oxygen from blood during the convulsion

Hypoxia

shortage of oxygen supply to a tissue that accompanies a tonic-clonic seizure can itself cause brain damage

Absence seizure

Not associated with convulsions

•A disruption of consciousness associated with a cessation of ongoing behavior

3-per-second spike-and-wave discharge

The EEG of an absence seizure is a bilaterally symmetrical -

Ketogenic diet

diet consisting of high levels of fat, moderate levels of protein and low levels of carbohydrates

Vagus nerve

Treatment of seizure include stimulation of the -

Parkinson’s disease

A movement disorder of middle and old age affecting about .1% of the population over the age of 55

Substantia nigra

PD is associated with the severe degeneration of the -, the midbrain nucleus whose neurons project via the nigrostriatal pathway to the striatum of the basal ganglia

Dopamine

there is little - in the substantia nigra and striatum of long-term PD patients

Lewy bodies

autopsy of PD reveal clumps of proteins in the surviving dopaminergic neurons of the substantia nigra called -

L-dopa

symptoms of PD can be alleviated by injections of -, the chemical from which the body synthesizes dopamine

Deep brain stimulation

treatment in which low intensity electrical stimulation is continually applied to an area of the brain stimulation through a stereotaxically implanted electrode

Subthalamic nucleus

deep brain stimulation involves stimulation of a nucleus that lies just beneath the thalamus and is connected to the basal banglia, the -

Huntington’s disease

progressive motor disease that rare, has a simple genetic basis, and is always associated with severe dementia

Huntingtin

HD is passed from generation to generation by a single mutated dominant gene called -