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