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150 Cards in this Set
- Front
- Back
what is contained in the posterior fossa |
cerebellum and brainstem
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what divides the anterior and middle fossas
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lesser wing of sphenoid
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what divides the middle and posterior fossas
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petrous portion of temporal bone and a sheet of meninges (tentorium cerebelli)
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layers of the scalp
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SCALP: skin, CT (subcutaneous), Aponeurotica, Loose areolar CT, Pericranium (periosteum)
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two layers of dura
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outer periosteal layer adherent to inner surface of skull and meningeal layer
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where does the meningeal layer of dura fold in away from the periosteal layer
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falx cerebri, tentorium cerebelli
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3 spaces/potential spaces that the meninges form
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1) epidural space 2) subarachnoid space 3) subdural space
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epidural space
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potential space btwn inner skull surface and dura
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where does the middle meningeal artery enter the skull
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via foramen spinosum and runs in epidural space; supplies dura
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subdural space
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potential space btwn the inner layer of dura and loosely adherent arachnoid
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what do the bridging veins transverse
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subdural space; drain cerebral hemispheres and pass through subdural space on the way to dural venous sinuses
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what do dural sinuses drain to
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sigmoid sinuses to reach internal jugular veins
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what do blood vessels in general travel through in the brain
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subarachnoid space, then send penetrating branches inward through pia
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cells lining the ventricles
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ependymal cells
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what are the walls of the third ventricle formed by
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thalamus and hypothalamus
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how do the lateral ventricles communicate with the 3rd ventricle
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interventricular forament of Monro
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how does the 3rd ventricle communicate with the 4th ventricle
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cerebral aqueduct traveling through midbrain
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roof and floor of the 4th ventricle
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cerebellum and pons/medulla
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foramena that CSF leaves from 4th ventricle
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lateral foramina of Luschka and midline foramen of Magendie
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total CSF volume in an adult and production
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150 cc; 20 cc/hour or 500 cc/day
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cisterns within subarachnoid space
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perimesencephalic (ambient, quadrigeminal, interpeduncular), prepontine, cisterna, and lumbar
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where is the ambient cistern
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lateral to midbrain
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where is the quadrigeminal cistern
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posterior to the midbrain; quad from the four bumps of superior and inferior colliculi
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interpeduncular cistern/fossa location
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ventral surface of midbrain btwn cerebral peduncles
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what CN exits the midbrain through the interpeduncular fossa
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CN III
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what is located in the prepontine cistern
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basilar artery and CN VI
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what substances can readily cross the cell membranes of blood-brain and blood-CSF barriers
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lipid soluble, inculding CO2 and O2
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how large are arachnoid vilus cells bulk transport abilities
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large enough to engulf entire RBCs
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circumventricular organs
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blood-brain barrier interupted allowing brain to respond to changes in chemical milieu of remainder of body
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where are circumventricular organs located
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median eminence and neurohypophysis - regulate and release pituitary hormones; also subfornical organ, pineal, subcommissural organ, area postrema, and organum vasculosum
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where is the area postrema
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caudal wall of 4th ventricle in medulla; aka chemoactic trigger zone
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what may be the fxn of organum vasculosum and lamina terminalis
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neuroendocrine fxns
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what fxn may the subfornical organ have
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fluid balance regulation
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what can disrupt the blood-brain barrier
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brain tumors, infections, and others
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vasogenic edema
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excessive extracellular fluid
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cytotoxic edema
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fluid accumulation within cells
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innervation of the dura
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supratentorial dura by CN V; posterior fossa CN X (and some by CN IX and 1st 3 cervical nerves
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firtification scotoma
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characteristic region of visual loss bordered by zigzagging lines resembling the walls of a fort; may be part of migrain aura
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complicated migraine
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accompanied by a variety of transient neurologic deficits like senory phenomenon, motor deficits, visual loss, brainstem findings in basilar migraine, impaired eye movements in opthalmoplegic migraine
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what should be ruled out if sudden explosive headache occurs
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subarachnoid hemorrhage via CT scan
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what affect does low CSF have on headache
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headache worse standing up than laying down
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increased intracranial P and headache
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worse laying down during night
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pseudotumor cerebri
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headache and elevated ICPs with no mass lesion
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temporal arteritis aka giant cell arteritis
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vasculitis affects temporal arteries and other vessels (enlarged and firm)
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how is temporal arteritis diagnosed
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erythrocyte sedimentation rate (ESR) and tempoeral artery biopsy
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when should meningitis be suspected and immediately tested for and treated
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headache with fever or meningeal irritation like stiff neck and sensitivity to light
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how do intracranial masses cause neurologic symptoms and signs
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1) compression and destruction of adjacent regions 2) intracranial P increase 3) displace nervous system structures - herniation
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mass effect
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any distortion of normal brain geometry due to mass lesion
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cerebral perfussion P
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mean arterial P minus ICP
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projectile vomiting
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occurs suddenly and without much nausea
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signs of elevated ICP
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headache, decreased alertness and attention, nausea and vomiting, papilledema
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how quickly does papilledema dvlp
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several days and is often not present in an acute setting
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what can diplopia result from
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downward traction on CN VI
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Cushing's triad
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hypertension, bradycardia, and irregular respirations; sign of increased ICP
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normal adult ICP
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less than 20 cm water or less than 15 mm Hg (torr)
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what should cerebral perfusion P be kept above
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50 mm Hg
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transtentorial herniation
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herniation of medial temporal lobe, especially uncus
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uncal herniation clinical triad
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blown pupil, hemiplegia, coma
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what causes a blown pupil
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compression of CN 3, usually ipsilateral to the lesion
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what causes hemiplegia
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compression of cerebral peduncles
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Kernohan's phenomenon
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countralateral corticospinal tract compressed due to uncal herniation of midbrain being pushed against opposite side of tentorial notch, ipsilateral loss since tracts haven't crossed yet
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central herniatin
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central downward displacement of brainstem; can cause traction of CN VI
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tonsillar herniation
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herniation of cerebellar tonsils downward through the foramen magnum
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subfalcine herniation
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cingulate gyrus and other brain structures herniate under falx cerebri
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what infarcts can occur due to subfalcine herniation
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anterior cerebral artery infarcts
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what infarcts can occur due to uncal herniation
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posterior cerebral artery herniation
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concussion
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reversible impairment of neurological fa=xn after minutes to hours following head injury
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postconcussive syndrome
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headaches, lethargy, mental dullness, and other symptoms up to several months after accident
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severe head trauma causes brain injury via what mechanisms
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1) diffuse axonal shear injury 2) petechial hemorrhages 3) intracranial hemorrhages 4) cerebral contusion 5) penetrating trauma 6) cerebral edema
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types of intracranial hemorrhage
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1) epidural (EDH) 2) subdural (SDH) 3) subarachnoid (SAH 4) intracerebral or intraparenchymal (ICH)
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epidural hematoma usual cause
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rupture of middle meningeal artery due to fracture of temporal bone by head trauma
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epidural hemorrhage image on CT
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lens-shaped convexity that doesn't spread past cranial sutures
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subdural hematoma usual cause
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rupture of bridging veins which are vulnerable to shear injury as they cross from arachnoid into dura
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subdural image on CT
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crescent-shaped hematoma over large area
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chronic subdural hematoma
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generally in elderly; slow oozing, blood collects over weeks/months
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acute subdural hematoma
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high impact velocity, generally occurs with subarachnoid and brain contusion
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age and denseness of subdural hemotoma on imaging
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new - hyperdense blood; 1-2 weeks isodense clot liquification; 3-4 weeks hypodense complete liquification; hematocrit effect - denser on bottom
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subarachnoid hemorrhage image on CT
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track down into the sulci following contrours of pia
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subarachnoid hemorrhage general cause
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nontraumatic and traumatic
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nontraumatic subarachnoid hemorrhage
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presents with worsening catastrophic headache; generally due to ruptured aneurysm, less often from AV malformation
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where do most saccular/berry aneurysms occur
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anterior circulation (carotids)- Anterior communicating 30%, posterior comm 25%, MCA 20%, vertebrobasilar system 15%
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what can an unruptured Pcomm aneurysm arising from the internal carotid cause
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painful 3rd nerve palsy
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why is it important to NOT use contrast when checking for aneurysm
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subarachnoid blood and contrast material both appear white on the scan, making small hemorrhages difficult to see
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LP and aneurysms
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only done if CT negative
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where do contusions occur
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side of impact (coup) and opposite side of impact (contrcoup) due to rebound
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cause of intracerebral or intraparenchymal (ICH) nontraumatically
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hypertension, brain tumors, secondary hemorrhage after ischemic infarction, cascular malformation, blood coagulation abnormalities, infectsions, veddel fragility due to amyloid, etc
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what does hypertensice hemorrhage tend to involve
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small penetrating blood vessels (basal ganglia, thalamus, cerebellum, then pons)
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lobar hemorrhage
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bleeding involves occipital, parietal, temporal, or frontal lobe; mast common is due to amyloid angiopathy
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vascular malformation categories
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1) AV malformations 2) cavernous malformations 3) capillary telangiectasias 4) venous angiomas
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AV malformations
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abnormal direct connections btwn arteries and veins
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cavernous malformations
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abnormally dilated vascular cavities lines by only one layer of vascular endothelium
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capillary tangiectasias
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small regions of abnormally dilated capillaries that rarely give rise to hemorrhage; usually incidental finding
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extracranial hemorrhage
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within ear, subcutaneous tissues
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cephalohematoma
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bleeding btwn skull and external periosteum in newborns
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subgaleal hemorrhage aka goose egg
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loose space btwn external periosteum and galea aponeurotica
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what can cause excess CSF
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overproduction, blockage, or slow reabsorption
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what can cause excess production of CSF
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rare, generally via tumor like choroid plexus papilloma
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clinical dividions of hydrocephalus
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communicating and noncommunicating
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in mild or slowly dvlping cases of hydrocephalus what is seen
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only a sixth nerve palsy may be seen
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how can hydrocephalus affect gait
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compress descending white matter trats from frontal lobes causing things like magnetic gait
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Parinaud's syndrome
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limited vertical gaze caused by dilation of the suprapineal recess of the posterior 3rd ventricle pushing down on the collicular plate of midbrain
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external ventricular drain
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fluid from lateral ventricles is drained into a bag outside the head
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ventriculoperitoneal shunt
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shunt tube passing from lateral ventricle out of skull, tunneled under skin to peritoneal cavity
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normal-pressure hydrocephalus
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chronically dilated ventricles
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clinical triad in normal-P hydrocephalus
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gait difficulties, urinary incontinence, and mental decline
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hydrocephalus ex vacuo
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excess CSF in region of brain tissue lost as result of stroke, surgery, atrophy, trauma, or other insult
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where are CNS tumors located in adults and kids
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adults: 70% supratentorial and 30% infratentorial; kids: 70% posterior fossa and 30% supratentorially
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tumors commonly associated with seizures
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oligodendrogliomas and meningiomas
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menginiomas arise from
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arachnoid villus cells; grow slow, appear as homogeneous enhancing areas arising from meningeal layers; associated with breast cancer
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pituitary adenomas
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can compress optic chiasm
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lymphoma arises from
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B lymphocytes and commonly involved regions adjacent to ventricles
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most common brain tumors of kids in posterior fossa
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astrocytoma, medulloblastoma, and ependymoma
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paraneoplastic syndromes
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remote effects on brain/CNS from cancer of the body; most common in small cell cancinoma, breast cancer, and ovarian cancer
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infectious meningitis
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infection of CSF in suarachnoid space caused by viruses, bacteria, fungi, or parasites
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features of meningeal irritation
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headache, lethargy, sensitivity to light and noise, fever, nuchal rigidity
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nuchal rigidity
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neck muscles contract involuntarily resulting in resistance to active or passive neck flexion, accompanied by neck pain
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acute bacterial meningitis
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CSF high WBC count with polymorphonuclear predominance, high protein, low glucose
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brain abscess
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expanding intracranial mass lesion, like a tumor, but with a more rapid course; bacterial infection
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epidural abscess in spinal cord presenting symptoms
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back pain, fever, elevated WBC count, signs of nerve root or spinal cord compression
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subdural empyema cause
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collection of pus in subdural space generally from extension of infection in nasal sinus or ear
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tuberculous meningitis cause
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inflammatory response in basal cisterns of brain
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Pott's disease
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involvement of epidural space and vertebral bones
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two most important spirochete infections in the nervous system
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neurosyphilis and Lyme disease
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aseptic meningitis cause
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can be due to meningeal involvement associated with CN palsies (especially optic, facial, and vestibulocochlear)
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meningovascular syphilis
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chronic meningeal involvment causes arteritis that results in diffuse white matter infarcts
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CSF in viral meningitis
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elevated WBC count, lymphocytic predominance, normal or mildly elevated protein, normal glucose (polymorphonuclear predominance may be present in early stages)
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viral encephalitis
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involve brain parenchyma
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herpes simplex
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most common cause of viral encephalitis, tropism for limbic cortex
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subacute sclerosing panencephalitis
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delayed, slowly progressive fatal encephalitis; measles can cause
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transverse myelitis
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inflammatory response in the spinal cord
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AIDS dementia complex
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most common neurologic manifestation of HIV
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highly active antiretroviral therapy (HAART)
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azidothymidine (AZT) plus 3TC plus protease inhibitor
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Progressive multifocal leukoencephalopathy (PML)
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caused by a papovavirus called JC virus and results in gradual demyelination of the brain; usually leads to death within 3 to 6 months
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what should be suspected in all HIV-pos patients with chronic headache
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cryptococcal meningitis (fungal infection); antigen must be checked in CSF for diagnosis
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most common cause of intracranial mass lesions in HIV positive patients
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toxoplasmosis
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second most common cause of inteacranial mass lesions in HIV positive patients
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primary central nervous system lymphoma (B cell lymphoma); diagnosed via biopsy of CSF PCR for epstein-barr virus
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cysticercosis cause
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ingestion of eggs of pork tapeworm
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cysticercosis effects
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forms multiple small cysts in muscles, eyes, and CNS; seizures common result along with headache, nausea, vomiting, lymphocytic meningitis, and focal deficits
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what occurs after cysticercosis organisms die
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leave 1-3 mm calcifications scattered throughout brain (brain sand)
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what fungus occasionally spreads from the nasal passages to the orbital apex causing apex syndrome
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aspergillus
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mucormycosis
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fungal infection mainly of diabetics in rhinocerebral from and involves the orbital apex
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what can exacerbate fungal infections
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steroids
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what are the main 2 fungi that infect brain parenchyma
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aspergillus and candidia; accompanied by intense inflammatory response
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prion pathology
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diffuse degeneration of brain and spinal cord with multiple vacuoles resulting in spongyform appearance
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presenting features of Creutzfeldt-Jakob disease
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rapidly progressive dementia, exaggerated startle response, myoclonus, visual distortions, ataxia
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what can impaired coagulation cause if a LP is performed
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iatrogenic spinal epidural hematoma, which can compress cauda equina
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what does the needle pass through in an LP
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subcutaneous tissues, ligaments of spinal column, dura, and arachnoid mater
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how can traumatic tap be distinguished from pathological subarachnoid hemorrhage
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1) number of RBC decreases from 1st to last tubes in traumatic tap 2) when cnetrifuges, supernatant may have yellowish or xanthochromic appearance as result of hemorrhage , none in traumatic tap
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when is a pterional craniotomy performed
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anterior circulation and basilar tip aneurysms, cavernous sinus, and suprasellar tumors
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suboccipital craniotomy is used with what structures
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cerebellopontine angle, vertebral artery, brainstem, lower cranial nerves
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