Chapter 23 - Nervous System Flashcards
meninges layers
dura mater: outer
arachnoid mater: AKA subarachnoid space; CSF here
pia mater: inner most; delicate as fuck
function of cerebrospinal fluid
cushion and protect brain
what structure makes cerebrospinal fluid
choroid plexus
components of CSF
clear
small amount of protein
glucose
two divisions of the nervous system
Central and peripheral
components of the brain
cerebrum
cerebellum
brain stem
where are vascular interconnections located on the brain
base of the brain
what can only move across the blood brain barrier
small, fat soluble molecules
what cells make myelin?
oligodendrocytes
what cells make cerebral spinal fluid
ependymal cells
what cells wrap around axons?
schwan cells
EEG
electroencephalogram - used to measure electrical activity of the brain
angiography
procedure that looks for abnormal distribution of blood vessels in the region of a lesion
when do genetic/developmental diseases typically start their deleterious forces?
within the first half of gestation
what is a neural tube defect?
incomplete development of brain, spinal cord, and/or meninges
what are the two types of neural tube defects?
spina bifida
anencephaly = without brain
many neural tube defects are caused by a deficiency in?
folate/folic acid
what tests do you use to diagnose neural tube defects?
ultrasound or amniocentesis
what is hydrocephalus?
large head from an accumulation of cerebral spinal fluid
causes of hydrocephalus (3)
-obstruction in the flow of CSF
-overproduction of CSF
-inability of arachnoid granulations to restore CSF back into circulation
hydrocephalus in children vs. adults
children - enlargement of skull
adults - swelling inward, pushing on brain
signs and symptoms of hydrocephalus
-dilated pupils
-increased BP
-headache
-nausea/vomiting
-seizures
-drowsiness/altered consciousness
treatment for hydrocephalus
-eliminate the cause
-reduce the pressure
-intracranial shunts
-osmotic agents
-craniotomy
-steroid therapy
-medically induced coma
-hypothermia to slow brain metabolism
what is meningitis
inflammation of the meninges
what is the most common cause of meningitis?
bacteria - gains access to brain and spinal cord via the blood
major signs and symptoms of meningitis?
-neck rigidity
-fever
-headache
diagnosis of meningitis
spinal tap to collect CSF
treatment of meningitis
-antibiotics
-steroids to reduce inflammation
what is encephalitis?
diffuse inflammation of the brain
what is encephalitis caused by?
viral infections; many are mosquito-borne
symptoms of encephalitis
-irritability
-drowsiness
-headache
how to diagnose encephalitis
depends on culture and type of viral agent by serologic testing
treatment for encephalitis
no specific treatment; you either die, recover fully, or partially recover with neurologic defecit
what is poliomyelitis
virus that destroys nerve cells in the spinal cord (causing paralysis)
what causes polio?
poliovirus
how is polio transmitted?
fecal-oral contamination
outcomes of polio
most asymptomatic (95%), less than 1% paralytic
what is a cerebrovascular accident?
aka: stroke
-sudden neurologic deficit caused by vascular occlusion; leads to infarcts
what is the fourth leading cause of death in the US?
stroke or CVA
what is the most common cause of CVA/stroke?
cerebral thrombosis
what is a cerebral embolus?
blockage of cerebral artery by a fragment of blood clot from arteriosclerotic plaque; less frequently
what is a cerebral hemorrhage?
excess bleeding usually from a ruptured cerebral aneurysm; MOST SERIOUS TYPE OF STROKE
how many patients die of CVAs caused by brain hemorrhage?
up to half of patients because of accumulation of blood; rapidly elevates intracranial pressure
signs and symptoms of CVAs
-impaired speech or consciousness
-hemiparesis
-poor coordination
-confusion
outcomes of CVAs
-1/3 die within 2 weeks
-1/3 recover w/ deficit
-1/3 recover with no deficit (dissolved embolus)
Traumatic brain injury (TBI)
brain collides with the inside of skull; causes bleeding, bruising, and tearing of nerve fibers
coup vs. contrecoup
coup = direct; primary impact
contrecoup = indirect; secondary impact
results of CNS trauma/tbi
-fracture
-injury within the brain (intraparenchymal)
-vascular injury
what is the most common head injury?
concussion
definition of cerebral concussion
immediate loss of consciousness for seconds to minutes
etiology of a concussion
-blunt force impact to head
-brain strikes and rebounds from skull
-disruption of normal brain activity (loss of consciousness)
epidural hemorrhage of brain
-hemorrhage above the dura mater; usually in meninges artery
-forms quickly; fatal within 24 hours
subdural hemorrhage of brain
-hemorrhage under dura mater
-slow, venous bleeding; 4-6 weeks
subarachnoid hemorrhage of brain
-hemorrhage between arachnoid and pia mater where CSF is
-arterial bleeding
-typically from circle of Willis
intracerebral hemorrhage of brain
-hemorrhage within brain tissue
treatment of TBIs; mild and severe
mild = bed rest and analgesic meds (painkillers)
severe =
-diuretics
-antiseizure and coma-inducing meds
-surgery to remove clots, repair fractures
-craniotomy
what is a seizure?
alteration of brain function caused by disorderly discharge of cerebral neurons (abnormal brain electrical activity)
epilepsy
2 or more unprovoked seizures occur more than 24 hours apart
causes of provoked seizures
-fever
-electrolyte imbalances
-hypoglycemia
-hypoxia
-arrhythmias
-CNS infection/damage
-head trauma
causes of unprovoked seizures
idiopathic; strong genetic basis
partial seizure
focal; only one small area of the brain
simple seizure
w/o loss of consciousness
complex seizure
loss of consciousness
generalized seizure
occurs in both hemispheres of brain, can be convulsive or nonconvulsive
absence (petit mal) seizure
brief loss of consciousness
atonic seizure
loss of muscle tone
myoclonic seizure
muscles contract
clonic seizure
repetitive jerking movements
tonic
muscle stiffness, rigidity
grand mal seizure
muscles contraction; loss of consciousness
how to diagnose a seizure
-EEG
-MRI/CT
treatment of seizures
-avoid precipitant
-anti-convulsants (reduce electrical activity)
-surgery (remove seizure focus)
degeneration of what is Alzheimer’s Disease
cortical neurons
degeneration of x = MS
myelin
degeneration of x = parkinson’s and huntington’s disease
basal ganglia
general etiology of neurodegenerative disorders
-genetic predisposition
-environmental toxins
-oxidative stress
-aging
multiple sclerosis definition
damaged myelin sheaths; disease of oligodendrocytes
what is the most common neurologic disability in young adults?
multiple sclerosis
-chronic, progressive, irreversible
what percentage of MS patients are unable to walk without assistance 15 years after onset?
50%
etiology of MS
autoimmune disease that attacks myelin
-genetic susceptibility
-environmental trigger
is MS associated with peripheral neurons?
no - central
symptoms of MS
-visual impairment
-urination
-motor weakness
-numbness
-fatigue
-mood swings
treatment of MS
-relieve symptoms
-drug therapy to slow progression
prognosis for MS
-no cure
-usually die from infections, not disease itself
what is dementia
irreversible deterioration of cerebral cortex
is dementia age related?
no - not normal part of aging
losses in dementia
-orientation
-memory
-language
-judgment
-decision making
what is the most common form of dementia?
alzheimer’s disease
what part of the brain is affected with alzheimer’s disease
cerebral cortex; frontal and temporal lobes
etiology of alzheimer’s
unknown; but it is irreversible, progressive, and chronic
what two features are associated with alzheimer’s disease?
-amyloid plaques
-neurofibrillary tangles
=decreased acetylcholine production
risk factors for alzheimer’s disease
-age
-chronic hypertension
-head injury (3x more likely to develop Alzheimers)
mult-infarct vascular dementia
cumulative brain damage from small strokes; 2nd most common type of dementia
what cells are affected with parkinson’s disease
basal ganglia (beneath the cortex)
cause of parkinson’s disease
unknown; but decreased dopaminergic neurons (less dopamine)
manifestations of parkinson’s
-disturbances of movement
-rigidity
-bradykinesia
-pill rolling tremor
-abnormal gout
-postural instability
how do you treat parkinson’s disease
drugs to increase dopamine; no cure
what cells are affected in huntington’s disease
basal ganglia (beneath the cortex)
what is huntington’s disease characterized by?
chorea = involuntary, gyrating movements, progressive dementia
what type of genetic neurodegenerative disease is Huntington’s disease?
autosomal dominant; age-associated
neoplasia of brain - metastatic tumors vs. primary
metastatic tumors are more common than primary tumors
glioma
poorest prognosis because located deep in the brain; doesn’t respond well to treatment
astrocytoma
cancer of the astrocyte
oligodendroglioma
cancer of the oligodendrocytes
lymphoma
cancer of T or B cells
meningioma
cancer of the meninges
is meningioma benign or malignant
benign in biological sense; depends where it is and what it presses on
most common signs and symptoms of brain neoplasms
-increased pressure
-edema
-generalized headache, vomiting, blurred vision, seizures
amyotrophic lateral sclerosis (ALS)
death of alpha motor neurons; affects upper and lower motor neurons - damaged nerve fibers
ALS only affects what type of muscle
skeletal
is ALS age-associated?
yes
is ALS a peripheral or central nervous system disease?
peripheral
cause of ALS
unknown
treatment of ALS
no treatment or cure
manifestations of ALS
-muscle atrophy
-paralysis of muscles
-respiratory problems
two forms of ALS
sporadic - 90%
familial - 10%
What is guillain-barre syndrome?
autoimmune disease that attacks peripheral nerves leading to inflammation and progressive weakness from extremities toward trunk
guillain-barre syndrome is polyneuropathic which means:
it affects many nerves in different parts of the body
symptoms of guillain-barre syndrome
weakness
tingling
can guillain-barre syndrome be life-threatening?
yes - breathing issues
bell palsy
unilateral facial nerve paralysis
what is guillan-barre syndrome usually preceded by?
viral or bacterial “flu-like” infection
cause of bell palsy
unknown
symptoms of bell palsy
-inability to control facial muscles
-twitching, weakness
-drooping eyelid
-drooling
prognosis of bell palsy
good; symptoms decrease within 2 weeks and complete recovery within 3-6 months *temporary
definition of headache
diffuse pain occurring in any portion of the head
primary headache
tension, migraine, cluster headaches
secondary headache
underlying structural problems
there are no pain receptors in the brain, so where does the pain come from
result of vasodilation – treat with vasoconstrictors
migraine headache
-recurrent, intense, throbbing headache
do migraines affect women or men more?
women - estrogen
aura (migraines)
visual disturbance before the pain of migraine
legally brain dead
two EEGs taken 24 hours apart show complete absence of electrical activity in the brain
loss of motor neurons is called
neurogenic paralysis
