A 36 year old male presents to your ED with headache and vomiting. He has a VP shunt in place. What on physical exam would suggest distal obstruction of the VP shunt? 

1. Overlying erythema

2. Inability to depress reservoir 

3. Delayed refilling of the reservoir

4. No refilling of the reservoir

B. Inability to depress reservoir 

VP shunts are placed to drain CSF when there is either excessive production or obstruction. There are many types that exist, however in general the shunt connects a ventricle to the peritoneum, with a reservoir and valve. When examining a patient with a VP shunt it is important to examine the shunt. Overlying erythema (choice A), may indicate shunt infection. Inability to depress the reservoir (choice B), indicates that there is an obstruction distal to the reservoir. No or slow refill (choice C and D) indicates that there is a more proximal obstruction to the reservoir.

If the patient begins to develop symptoms of life threatening increased ICP, an emergent shunt tap is indicated during which you sterilely insert a butterfly into the reservoir and slowly withdraw CSF (see youtube video below).

https://www.youtube.com/watch?v=PiKc_MFp_4E 

References:

Ladde J. Central nervous system procedures and devices. In: Tintinalli J, ed. Tintinalli’s Emergency Medicine. 7th ed. New York City, NY: McGraw-Hill; 2011:1180–1183.

Schlosser, H., Crawack, H., Miethke, C., Knitter, T., Zeiner, A., & Sprung, C. (2016). An improved reservoir for the flushing test to diagnose shunt insufficiency, Neurosurgical Focus FOC, 41(3), E14. Retrieved Aug 11, 2021, from https://thejns.org/focus/view/journals/neurosurg-focus/41/3/article-pE14.xml