Ventricular and Vascular System Stephens Test #2 Flashcards
Which ventricles are frequently enlarged in hydrocephalus?
Lateral
What foramen would a choroid plexus ependymoma obstruct?
Interventricular foramen of Monroe, which connects the lateral ventricles to the third
What would a midbrain tumor such as an astrocytoma disrupt?
CSF flow from third ventricle through the cerebral aquaduct into the fourth ventricle resulting in hypertrophied lateral ventricles
What is Syringomyelia?
The central canal enlarges and develops its own cavity called syrinx. It causes patients to have bilateral anesthesia of shoulders and upper limbs
Where are choroid plexuses located and what is the significance?
Located on floors of lateral and roof of third and fourth ventricles. They produce CSF
Describe the composition of CSF.
similar to blood ultrafiltrate with higher concentrations of sodium, chloride, and magnesium. Lower concentrations of potassium and calcium and glucose and protein
Presence of greater than ___ RBC’s or lymphocytes is abnormal?
six
What is normal CSF pressure and amounts?
100-200 mm of water and 20-25 ml in ventricles and 140 ml in the system
How does transient hydrocephalus occur with SAH?
The arachnoid villi can become temporarily blocked with a sub arachnoid hemorrhage and cause increase in pressurer
Describe flow of CSF
From ventricular system to subarachnoid space to the venous system via venous lacunae
How does hydrocephaly differ in infants/young children vs adults?
Infants and young children have fontanelles or unfused sutures while adults have fused sutures. The fused sutures do not allow for the head to expand therefore pressure builds intracranially. With infants and young children their heads expand due to the lack of fusion of the sutures.
What is external hydrocephalus?
Excessive accumulation of CSF in subarachnoid space with enlargement of that space by compression of CNS. can be supratentorial, infratentorial or both
What is supratentorial external hydrocephalus?
most commonly associated with senile atrophy of the cortex as seen with alzheimers
What is infratentorial external hydrocephalus?
seen in combo with communicating hydrocephalus
What is internal/noncommunicating hydrocephalus?
CSF doesn’t drain into subarachnoid space due to obstruction of intraventricular foramen, cerebral aqueduct, and medial and lateral foramina. Results in dilation of ventricles proximal to obstruction with.
What is communicating hydrocephalus?
Combo of infratentorial external and internal hydrocephalus. Due to adhesions and fibrosis in the subarachnoid spaces, cerebral edema or uncal herniation the space btw tentorial notch and midbrain can be obstructed. CSF can freely move through ventricular system, but cannot circulate over cerebrum to be reabsorbed at arachnoid villi next to and in the superior sagittal sinus
What supplies most of the blood to the brain?
ICA and then vertebral
How long does it take for a person to become unconscious if blood flow is interupted?
5-20 seconds