Cranium, ventricles, & meninges Flashcards
The blood-CSF barrier is formed by
Choroid epithelial cells
Usual cause of subdural hematoma
Rupture of bridging veins, which are particularly vulnerable to shear injury
The middle meningeal artery runs through the
Epidural space
The blood-brain barrier is made up of
Capillary endothelial cells
Consequences of early hydrocephalus on brain development
Stretch or destroy CC; affects WM tracts, esp. projection fibers near midline; disrupt myelination, resulting in decreased cortical mantel; decreased brain mass, thinning of posterior brain regions; multiple surgeries to correct shunt
Radiological appearance of epidural hematoma
Lens-shaped biconvex hematoma, usually does not spread past cranial sutures where dura is attached to the skull
Mild central herniation can lead to traction on which cranial nerve?
CN VI, producing lateral rectus palsy
Normal intracranial pressure
Meninges, from inside to outside
Pia, arachnoid, dura
Tentorium cerebelli
Tentlike sheet of dura that covers the upper surface of the cerebellum
Cisterns
Widening of subarachnoid space to form large CSF lesions
Symptoms of increased CSF
Headache worse lying down, altered mental status (irritability, depressed alertness & attention), nausea/vomitting, papilledema, visual loss, diplopia
CSF enters the subarachnoid space via
Lateral foramina of Luschka & midline foramen of Magendie
Subarachnoid space
CSF-filled space between the arachnoid & pia; major arteries of the brain travel through this space
Falx cerebri
Separates the 2 cerebral hemispheres
What is the normal adult volume of CSF?
150cc, 500cc produced per day
Choroid plexus
Epithelial tissue in ventricular system that secretes CSF; found in the lateral ventricles & the roof of the 3rd & 4th ventricles
The bridging veins run through the
Subdural space
What type of herniation can cause infarcts in the ACA territory?
Subfalcine herination
Xanthochromia
CSF discoloration due to presence of blood for 1+ day; associated with subarachnoid hemorrhage
Most common cause of epidural hematoma
Rupture of the middle meningeal artery due to fracture of the temporal bone by head trauma
Arachnoid layer
Adheres to inner surface of dura
The cervicomedullary junction occurs at the level of the
Foramen magnum
What type of herniation is associated with compression of the medulla
Tonsillar herniation Leads to respiratory arrest, BP instability, death
Radiological appearance of subarachnoid hemorrhage
Blood tracks down into sulci following contours of the pia
Pia mater
Adheres closely to the surface of the brain & surrounds the initial portion of each blood vessel as it penetrates the brain surface
Hydrocephalus can result from
Increased production/decreased absorption of CSF Blockage of one of the normal outflow pathways of the ventricular system
Kernohan’s phenomenon
As midbrain is pushed to side by uncus in uncal herniation, it is pushed away from the side of the mass. The side opposite the mass then becomes compressed against the tentorial notch, leading to ipsilateral hemiplegia.
What is the most common cause of lobar hemorrhage?
Amyloid angiopathy
Tentorium cerebelli
Covers the upper surface of the cerebellum
Pseudotumor cerebri
Elevated ICP/edema without mass lesion
Leptomeninges
Pia & arachnoid
Neuropsych effects of hydrocephalus in children
PIQ< language problems with rapid retrieval of info, automaticity, language discourse, cocktail party speech Deficits in both verbal & visual memory, exec deficits
Communicating hydrocephalus
Excess CSF due to either bad absorption or over production
Colloid cyst
Benign neoplasm composed of epithelial cells surrounded by a capsule & filled with a gelatinous substance; commonly arise from the roof of the 3rd ventricle
Ventriculostomy
Establishes free communication between the floor of the 3rd ventricle & the underlying interpeduncular cistern
Hypertensive hemorrhages are most common in what areas of the brain?
BG, thalamus, cerebellum, pons
Is vasospasm more common in traumatic or nontraumatic subarachnoid hemorrhage?
Nontraumatic
Symptoms of chronic subdural hematoma
HA, cognitive impairment, unsteady gait
Cerebral aqueduct/Aqueduct of Sylvius
Canal draining CSF from 3rd to the 4th ventricles through the midbrain; common site of obstruction causing childhood hydrocephalus
What pattern of IQ performance is typically observed in children with early-onset hydrocephalus?
VIQ>PIQ
Calvaria/calvarium
Upper dome-like portion of the skull
Risk factors of pseudotumor cerebri
Female, adolescent, obesity, menstrual abnormalities
Clinical triad of uncal herniation
Blown pupil (compression of CN III), HP (compression of cerebral peduncles), coma (distortion of midbrain RF)
What is the most common cause of nontraumatic subarachnoid hemorrhage?
Rupture of arterial aneurysms (75-80%)
The anterior, middle, & posterior fossa contain which brain structures?
Anterior - frontal lobe Middle - temporal lobe Posterior - cerebellum & brainstem
Radiological appearance of subdural hematoma
Crescent-shaped
Which brain region is most often affected by hydrocephalus?
Posterior regions
Obstructive hydrocephalus
Obstruction of CSF drainage from the lateral & 3rd venricles; commonly seen with brainstem tumor or posterior fossa tumor; can result from congenital stenosis of aqueduct of Sylvius
What 3 ways is hydrocephalus classified?
Complicated or noncomplicated Communicating or noncommunicating Congential or postnatal
Cushing’s triad
HTN, bradycardia, irregular respiration
Most common cause of perinatal & postnatal hydrocephalus (besides spina bifida)
Intraventricular hemorrhage
Vasogenic vs cytotoxic edema
Vasogenic: excessive extracellular fluid Cytotoxic: excessive intracellular fluid within brain cells caused by cellular damage
Cocktail party syndrome (CPS)
Communication style characterized by excessive verbiage that lacks clarity, organization, & relevance (often seen in childhood hydrocephalus)
In what areas is the blood-brain barrier broken?
Pituitary gland (entry of chemicals that influence hormones), pineal gland (entry of chemicals that affect day-night cycles), area postrema (entry of toxic substances that induce vomiting
Two layers of the dura
Periosteal & meningeal
Children with prenatal obstructive hydrocephalus are more prone to exhibit difficulties with
Visuospatial & visuomotor abilities
How is increased CSF/ICP treated?
Steroids, mannitol, hyperventilation (vasoconstriction), shunt, external ventricular drain
Dura mater
Outermost meningeal layer
Alterations in the amount of CSF may reflect
Nervous system impairment (bacterial meningitis, myelitis, MS, SAH) or germ cell proteins
Symptoms of nontraumatic subarachnoid hemorrhage
Sudden catastrophic HA, meningeal irritation, CN & other focal deficits, impaired consciousness
Symptoms of pseudotumor cerebri
Generalized, bilateral headache, bilateral VI palsy, visual deficits due to swelling of optic disk
Falx cerebri
Suspended from roof of cranium, separates left & right hemispheres
