Test 1 Flashcards
Apraxia
Verbal apraxia refers to difficulty in forming and organizing intelligible words although the musculature is intact.
Anopsia
blindness in one eye resulting from complete lesion of the optic nerve before the optic chiasm
Bitemopral hemianopsia
blindness in both lateral visual fields (usually from pituitary tumors or aneurysms)
Homonymous hemianopsia
half-blindness involving both eyes with loss of visual field on the same side of each eye
Cerebral autoregulation
a protective mechanism that enables the brain to receive a consistent blood flow over a range of systemic blood pressures
- vessel diameter changes in response to the changes in arterial pressure
Vasogenic edema
most common type of cerebral edema
characterized by a disruption in the blood-brain barrier and the inability of the cell walls to control movement of water in and out of cells
common processes leading to this are brain tumors, cerebral abscess, stroke, and cerebral trauma
Cytotoxic edema
charaterized by swelling of the individual neurons and brain cells
cell membrane cannot maintain an effective barrier so both water and salt enter the cell, causing swelling, loss of function, and cellular death
Uncal herniation
herniation of the medial temporal lobe through the tentorium, where it pushes against the brain stem
Central herniation (supratentorial)
describes the downward displacement of the diencephalon and parts of the temporal lobes through the tentorium, causing compression of the brain stem
Central herniation (infratentorial)
describes a downward displacement of the brain stem into the spinal cord
ICP increases with increases in:
Intrathoracic pressure – coughing, sneezing
Intraabdominal pressure – Valsalva maneuver
Metabolic demands – seizures, shivering
How the brain compensates
increasing CSF absorption
displacing CSF into spinal subarchnoid space
collapsing the cerebral veins and dural sinuses
Dispensibility of the dura
Increasing venous outflow
Decreasing CSF production
Changing intracranial blood volume through constriction and dilation
Slight compression of brain tissue
Cerebral blood flow
the amount of blood in mL passing through 100 g of brain tissue in 1 minute.
Akinetic mutism
unresponsiveness to the environment, the patient makes no movement or sound but sometimes opens eyes
Locked-in syndrome
patient is unable to move or respond except for eye movements due to a lesion affecting the pons
Cerebral Perfusion Pressure
Normal CPP is 70-100 mm Hg
50-60 mmHg needed for adequate perfusion
Early signs of ICP
Change in LOC – most sensitive indicator (first)
Ocular signs – ipsilateral pupillary changes
Decrease in motor function - contralateral
Headache – usually worse
Cushing’s Triad
Classic sign of increase ICP include an elevated systolic blood pressure in conjunction with a widening pulse pressure, slow bounding pulse, and respiratory irregularities
Cheyne-Stokes Breathing
hemispheric disease or metabolic brain dysfunction- Cycles of hyperventilation and apnea – Referred to Death Breath
- Heavy, deep breathing, rate is increased and irregular, hard to get oxygen in apnea
Indications for ICP monitoring
stroke brain tumor postcardiac arrest carniotomy coma severe brain surgery hemorrhage ischemic infarction hydrocephalus
Contraindications for ICP monitoring
Coagulopathy
systemic infection
CNS infection
Infection at the site of device insertion
A waves
signifies ischemia (prolonged abnormal ICP) rapid increases of pressure ranging from 20-50 mm Hg over a period of 20 minutes or more
B waves
signifies intracranial herniation (talk to families about stopping life support)
produced by ICPs up to 50 mmHG (between 5 and 20 minutes)
Positioning
place head of bed flat or 30-45 degrees elevation to facilitate venous drainage
Diabetes insipidus
look at s/s, labs including urine, treatments with meds, expected response to meds
SIADH
look at s/s, labs including urine, treatments with meds, expected response to meds
Hypoventilation
after cerebral trauma can lead to respiratory acidosis. As the CO2 increases & O2 decreases, cerebral hypoxia & edema can result in secondary brain trauma
Hyperventilation
produces respiratory alkalosis with increased O2 and decreased CO2 causing vasoconstriction of cerebral blood vessels
Diuresis
Considered a cornerstone in the treatment of increased ICP
Osmotic diuresis pulls water out of brain tissue into systemic circulation where it’s removed by the kidneys
Mannitol is the agent most commonly used
Care must be taken to prevent a drop in CPP
Must monitor serum osmolality & lytes, esp. Na
Must monitor renal function
Other commonly used drugs – Bumex, Lasix
Shivering
Avoid shivering
Muscle relaxants reduce shivering
Most common medications administered:
Thorazine – depresses thermoregulation in the hypthalamus and reduces peripheral vasoconstriction, muscle tone and shivering
Demerol – relaxes the smooth muscle and reduces shivering
Mannitol
hypertonic crystalloid solution that decreases cerebral edema by increasing intravascular osmolality
typically administered as a bolus IV infusion
immediate plasma-expanding effect of mannitol reduces blood viscocity, increaing cerebral blood flow and cerebral oxygen metabolism
it lowers cerebral blood volume and ICP, while maintaining constant cerebral blood flow
Propofol
fat-soluble anesthetic administered as a continous infusion to decrease agitation in the critically ill patient
patients must be intubated and mechanically ventilated
hypotension is common
frequent BP monitoring is needed
Neuromuscular blockade
last resort
decreases the brains demand for oxygen and lowers the ICP
necessitates mechanical ventilation with full support
complications include tachycardia, hypotension, and dysrhythmias
Barbiturate coma
for a patient with severe ICP
may be induced to decrease metabolic activity and preserve brain function
criteria
- GCS less than 7
- ICP greater than 25 mmHg at rest for 10 minutes
- failed maximal interventions including CSF drainage, mannitol, analgesia, and sedation
Taper over 24-72 hours
Decompressive Craniectomy
part of the skull (“bone flap”) is removed to relieve brain swelling
bone flap is replaced at a later date after the swelling has decreased
widely used for patients with malignant cerebral edema after a traumatic brain injury
Craniotomy
a section of the skull is removed to facilitate accessing the brain underneath and then replaced
performed to remove space-occupying lesion, to evacuate hematomas, or to reverse herniation
may also be used to clip an aneurysm
Risks include cerebral edema and intracerebral hemorrhage
Carotid Endarterectomy
in patients with high-grade carotid stenosis, it may be performed to prevent a stroke
the procedure removes atherosclerotic plaque that has accumulated inside the carotid artery to restore blood flow
Acceleration injuries
a moving object strikes the stationary head
Acceleration-deceleration injuries
the head in motion strikes a stationary object
Coup-contrecoup injuries
the brain “bounces” back and forth within the skull, striking both sides of the brain
Rotation injuries
the brain twists within the skull, resulting in stretching and tearing of blood vessels and shearing of neurons
Penetration injuries
a sharp object disrupts the integrity of the skull and penetrates the brain tissue
Contusion
result from laceration of the microvasculature that causes bruising or, or bleeding into, the brain tissue
diagnosis with a CT
complications of a cerebral contusion include intracerebral hematoma and cerebral edema
cerebral edema peaks 24-72 hours after injury increasing the ICP
Cerebral brain flow
CBF is the amount of blood in mL passing through 100 g of brain tissue in 1 minute.
The maintenance of blood flow to the brain is critical because the brain requires a constant supply of oxygen and glucose.
Brain uses 20% of the body’s oxygen and 25% of its glucose.
Pinpoint fixed pupils
pons injury or drugs (cocaine)
Fixed midposition
midbrain injury
Lumbar Puncture
CSF
L3-L5
clear
no bacteria, glucose
Cerebral Perfusion Pressure
Normal is 70-100 mmHg
50-60 needed for adequate perfusion
Shivering medications
thorazine- depresses thermoregulation in the hypothalamus and reduces peripheral vasoconstriction, muscle tone and shivering
demerol- relaxes the smooth muscle and reduces shivering
Steroid protocol for spinal cord injuries
Methylprednisolone- bolus dose of 30 mg/kg
follow by infusion at 5.4 mg/kg/hr for 23 hours
initiate within 6-8 hours of injury
autonomic dysreflexia
uncontrolled hypertension above T6 sweating bradycardia massive headache common cause is full bladder, rectum, or anything sharp that hurts the patient
Neurogenic shock
due to the loss of function of the autonomic nervous system
blood pressure, heart rate decreases (hallmark sign!!!), and cardiac output decreases
venous pooling occurs due to peripheral vasodilation
paralyzed portions of the body do not perspire
may give atropine to speed up heart
Spinal Shock
a sudden depression of reflex activity below the level of spinal injury
muscular flaccidity and lack of sensation and reflexes
usually 24-72 hour period of paralysis, hypotonia, and areflexia
development of spasticity indicates recovery
Injury above T-1 level
quadriplegia
injury below T-1 level
paraplegia
