Page 566 - First Aid for the USMLE Step 1 2020, Thirtieth edition [MedicalBooksVN.com]_Neat
P. 566
522 SecTioN iii Neurology aNd Special SeNSeS ` neurology—PAthology Neurology aNd Special SeNSeS ` neurology—PAthology
Hydrocephalus CSF volume ventricular dilation +/− ICP.
Communicating
Communicating CSF absorption by arachnoid granulations (eg, arachnoid scarring post-meningitis) ICP,
hydrocephalus papilledema, herniation.
Normal pressure Affects the elderly; idiopathic; CSF pressure elevated only episodically; does not result in increased
hydrocephalus subarachnoid space volume. Expansion of ventricles A distorts the fibers of the corona radiata
triad of urinary incontinence, gait apraxia (magnetic gait), and cognitive dysfunction. “Wet,
wobbly, and wacky.” Symptoms potentially reversible with CSF drainage via lumbar puncture or
shunt placement.
Noncommunicating (obstructive)
Noncommunicating Caused by structural blockage of CSF circulation within ventricular system (eg, stenosis of
hydrocephalus aqueduct of Sylvius, colloid cyst blocking foramen of Monro, tumor B ).
Hydrocephalus mimics
Ex vacuo Appearance of CSF on imaging C , but is actually due to brain tissue and neuronal atrophy
ventriculomegaly (eg, Alzheimer disease, advanced HIV, Pick disease, Huntington disease). ICP is normal; NPH
triad is not seen.
A B C
FAS1_2019_12-Neurol.indd 522 11/8/19 7:39 AM
