Ch 1: Clinical Correlates pg 20-25 Flashcards
what is clinically important about the dural venous sinuses?
most of the cerebral venous blood collects in the dural sinuses and drains into the internal jugular veins
also the site of resorption of CSF from subarachnoid space through arachnoid granulations that protrude into sinuses
how can skull trauma cause a subdural hematoma?
can cause shearing of bridging veins (cerebral veins that drain into dural sinuses and transverse the subdural space)–>venous blood may accumulate in the subdural space–>subdural hematoma
how will a subdural hematoma look on a CT scan?
crescent-shaped hematoma
- venous blood supply is slowly accumulating
how can skull trauma cause an epidural hematoma?
may lacerate a middle meningeal artery
what will a hematoma caused by a lacerated middle meningeal artery look like?
biconvex, lens-shaped epidural hematoma
an epidural or subdural hematoma can compress part of the brain and cause….
tentorial herniation, tonsillar herniation, or subfalcine herniation
what is a tentorial herniation and what symptoms may be seen?
- uncus (medial part of temporal lobe) herniates through the tentorial notch of the dura and compresses the brainstem
- PCA may also be compressed
- contralateral hemiparesis, dilated/blown pupil (compression of CN III), deterioration of cardiovascular and respiratory functions (–>coma)
what is kernohan’s phenomenon?
brainstem is compressed against opposite side of the tentorial notch–>hemiparesis that is ipsilateral to the herniation (85% have compressed ocular nerve compression)
what is tonsilar herniation ad what symptoms may be seen?
- tonsil of cerebellum herniates inferiorly toward the foramen magnum and compresses the medulla
- respiratory compromise and death
what is subfalcine herniation?
cingulate gyrus herniates medially under the falx cerebri (fold of meningeal dura in the interhemispheric sulcus) and may compress an ACA
what connects the lateral ventricles to the third ventricles?
interventricular foramen of Monro
what connects the third ventricles to the 4th ventricles?
cerebral aqueduct
where do CSF exit the ventricles?
only the 4th ventricle contains openings where CSF can exit and enter the subarachnoid space
what is hydrocephalus?
increase in the volume of CSF–>dilation of 1 or more ventricles
what causes a communicating hydrocephalus?
impaired adsorption of CSF at the arachnoid granulations or a tumor in the subarachnoid space that impedes CSF flow–>inc volume of CSF in ventricles and subarachnoid space
what causes a normal pressure hydrocephalus? who is it most commonly found in? what symp are seen?
form of communicating hydrocephalus that is common in elderly and also caused by impaired adsorption–>chronically enlarged ventricles
mental decline, urinary incontinence, abnormal gait (wacky, wet, wobbly)=apraxic gait (no weakness but patient shuffles)
what causes noncommunicating hydrocephalus? where in the ventricular system does it commonly occur?
obstruction to CSF flow inside the ventricular system
- common in cerebral aqueduct of infants
- also intraventricular foramen or 4th ventricles foramens
what is hydrocephalus ex cavuo?
increase in ventricular size and an increase in the volume of CSF secondary to a pathological loss of brain tissue
in MS and inflammatory CNS disease, what chemical composition changes are seen in CSF?
oligoclonal immunoglobulin bands are detected
in acute bacterial infections and meningeal tumors what chemical composition changes are seen in CSF?
decrease in glucose concentration
in patients with bacterial meningitis, what changes in the CSF are seen?
WBC elevated (>4000/mm^3)
in patients with subarachnoid hemorrhage or bloody lumbar puncture, what changes in CSF are seen?
RBC present
what can increase intracranial CSF pressure?
- space occupying lesion in skull or vertebral canal such as tumors, hematomas, or hemorhages from vascular disease/trauma, abcesses and AVMs
- CSF 200-600 mm H2O
what are signs of increased intracranial pressure?
- headaches, mental status changes with altered level of consciousness, papilledema, projectile vomiting
- Cushing’s triad: hypertension, bradycardia, irregular respirations
