Week 11a: Brain Injury, Seizure disorders, Stroke, Sleep Flashcards
What are 3 examples of excitatory neurotransmitters?
- glutamate
- aspartate
- acetylcholine
What are two examples of inhibitory neurotransmitters?
- GABA
- Glycine
What is the dominant inhibitory neurotransmitter in the higher brain areas?
GABA
What is the dominant inhibitory neurotransmitter in the brainstem and spinal cord?
glycine
Inhibitory neurotransmitters
decrease the rate of neuronal firing by hyperpolarzing the neuron
Excitatory neurotransmitters
increase the rate or likelihood of a neurone firing by depolarizing the neuron
Causes of overstimulation of excitatory neurotransmitters?
- stroke
- hypoglycemic injury
- trauma
- Huntington’s disease
- alzheimers
deficits in levels of consciousness, from mild confusion to stupor or coma, indicates…?
either direct injury to the RAS or to both the cerebral hemispheres concurrently
What are some characteristics of a vegetative state?
- absence of awareness of self and environment
- inability to interact with others
- absence of sustained or reproducible voluntary behavioural responses
- lack of language comprehension
- hypothalamic and brainstem action to sustain life
- bowel and bladder incontinence
- variably preserved cranial nerve and spinal cord reflexes
- condition has continued for at least one month
What are metabolic factors that increase cerebral blood flow?
- carbon dioxide (hypercapnia)
- Hydrogen Ion (decrease in pH)
- Oxygen concentration (hypoxia)
factors that increase the cerebral blood flow also increases?
intracranial pressure
What ia a normal intracranial pressure?
0-15 mmHg
what is an ominous late sign of increased intracranial pressure and impending herniation?
cushings triad
Cushing’s triad
- hypertension with widened pulse pressure
- bradycardia
- changes in respiratory pattern in the presence of increased ICP (decreased RR)
brain herniation occurs when…?
when increased ICP causes the abnormal protrusion of brain tissue through openings in rigid intracranial barriers (tectorial notch)
Increased intracranial pressure in infants:
- irritability
- change in the pitch of the babies cry
- bulging fontanels
- lethargy
- flat affect
- poor feeding
- may develop macrocephaly and/or split sutures
Increased ICP in children:
- retinal hemorrhage with increased ICP should raise suspicion of non-accidental head trauma
- “sun-setting” appearance of the eyes
What is the formula for measurement of cerebral perfusion pressure?
CPP = MAP - ICP
When CPP is less than 60 mmHg….
cerebral blood flow is compromised and auto regulation is impaired
CPP should be kept between?
60 - 70 mmHg in patients with elevated ICP to avoid ischemic injury
CPP more than 70 mmHg….
should be avoided because of increased risk for adult respiratory distress syndrome
What are 3 drugs used to lower ICP?
- manitol
- propofol
- benzodiazepines
What other drugs can be used to decrease increased ICP?
- analgesics
- anti-epileptics for prevention of seizures
- glucocorticoids: dexamethasone
- antipyretics
- antihypertensive meds
what are some interventions for increased ICP?
- positioning
- activity management
- airway management
- hyperventilation
- bowel management
cingulate (subfalcine) brain herniation involves?
the cerebral artery
cingulate (subfalcine) brain herniation clinical sign?
leg weakness
Central transtentorial brain herniation involves?
the reticular activating system and corticospinal tract
Central transtentorial brain herniation clinical signs?
altered LOC, decorticate posturing, rostral-caudal deterioration
uncal brain herniation involves?
the cerebral peduncle, occulomotor nerve, posterior cerebral artery, cerebellar tonsil, and respiratory centre
uncal brain herniation clinical signs?
hemiparesis, pupil dilation, visual field loss, respiratory arrest
hydrocephalus
an abnormal increase in CSF volume in any part or all of the ventricular system
vasogenic cerebral edema
occurs with conditions that impair the function of the BBB and that allow transfer of water and protein from the vascular into the interstitial space. Ex: sepsis
cytotoxic cerebral edema
involves an increase in intracellular fluid
interstitial cerebral edema
edema in the central white matter as in hydrocephalus affecting the brain
primary or direct brain injuries
- damage is caused by an impact
- include diffuse axonal injury, and the focal lesions of laceration, contusion and hemorrhage
secondary brain injuries
- damage results from the subsequent brain swelling, infection and cerebral hypoxia
- often diffuse or multifocal, including concussion, infection and hypoxic brain injury
what are the symptoms of post concussion syndrome?
- headache
- irritability
- insomnia
- poor concentration and memory
an immediate and transient loss of consciousness accompanied by a brief period of amnesia after a blow to the head
concussion
Which type of hematoma is usually caused by head injury in which the skull is fractured?
epidural hematoma
which type of hematoma develops between the inner table of the bones of the skull and the dura
epidural hematoma
which type of hematoma is usually the result of a tear in the small bridging that connect veins on the surface of the cortex to the dural sinuses
subdural hematoma
which type of hematoma develops in the area between the dura and the ararchnoid (subdural) space?
subdural hematoma
which type of hematoma may be single or multiple and can occur in any lobe of the brain but are most common in the frontal or temporal lobes?
traumatic intracerebral hematoma
inflammation of the Pia matter, the arachnoid, and the CSF filled subarachnoid space
meningitis
infection of the parenchyma of the brain or spinal cord
encephalitis
status epilepticus
continual seizures that do not stop spontaneously
first line treatment of status epileptics
benzodiazepines
what are the 4 mechanisms of action of drugs for seizures and epilepsy
- increasing the stimulation of GABA receptors
- Reduce Na+ influx into neurons
- Reduce Ca2+ influx into neurons
- block glutamate receptors
barbiturates are indicated primarily for?
tonic clonic seizures
benzodiazepines are indicated primarily for?
absence and myoclonic seizures
gabapentin is indicated for?
partia seizures
what are 3 types of drugs that stimulate GABA receptors?
- barbiturates
- benzos
- gabapentin
what is the prototype drug for seizures
phenobarbital
phenobarbital is indicated for?
most seizure types except absence seizures
adverse effects of phenobarbital?
- respiratory depression
- hypotension
- drowsiness, sedation, excitation (children), difficulty focusing, confusion, depression, headache
therapeutic effects and uses of diazepam
- status epilepticus
- prevention of seizures
- anti anxiety, sedative hypnotic
adverse effects of diazepam
- drowsiness
- fatigue
- dizziness
risks of IV delivery of diazepam
- risk of muscle weakness
- hypotension
- respiratory depression
3 examples of drugs that reduce Na+ influx
- phenytoin
- carbamazepine
- valproate
Phenytoin is indicated for?
all seizures except absence seizures
carbamazepine is indicated for?
tonic-clonic and partial seizures
valproate is indicated for?
absence and tonic-clonic seizures as well as bipolar disorder
phenytoin has many…?
drug interactions!
what are some adverse effects of phenytoin?
- lethargy, drowsiness, dizziness
- headache
- bradycardia, hypotension
- agranulocytosis, leukopenia, thrombocytopenia
- rashes
what is an adverse effect of valproic acid
prolonged bleeding and clotting times
TIA
a mini stroke. usually resolves within 24 hours. A warning sign for a stroke
What happens during a stroke?
- glutamate release
- Ca influx
- membrane depolarization
- apoptosis
- ischemic penumbra
ischemic penumbra
central core of dead or dying cells, surrounded by an ischemic band or area of minimally perfused cells called the penumbra
Dysarthria
weak muscle control resulting in slurred speech
dysphagia
problems swallowing including coughing or choking when eating or drinking
aphasia
impairment of language and speaking
Expressive aphasia
includes speaking any words or saying the correct words
apraxia
dysfunction in moving the muscles needed in the correct order and sequence
dyslexia
trouble reading
dysgraphia
trouble writing
agnosia
inability to recognize and identify objects or persons
hemianopia
blindness in one half of the visual field
which type of CVA involves awareness of deficits, anxiety and depression
Left
TPA is usually given within?
3 hours
diagnosis of sleep apnea
- sleep studies
- EOG
- EEG
- polysomnography
signs and symptoms of sleep apnea
- noisy snoring
- insomnia
- abnormal movements during sleep
- morning headaches
- excessive daytime sleepiness
- cognitive and personality changes
- sexual impotence
- systemic hypertension
- Brady cardia (ventricular tachycardia may occur in severe hypoxemia)
- severe cases: pulmonary hypertension, cor pulmonale, polycythemia
benzodiazepines can reduce…?
REM sleep
benzodiazepines are antagonized by?
flumazenil
therapeutic effects of lorazepam
- GAD
- anxiolytic, sedative-hypnotic
- anti-seizure
- pre-anesthetic
tolerance to barbiturates can promote…?
tolerance to opioids and other CNS depressants
