What is the sensitivity of shunt series and head CT for detecting cerebrospinal fluid shunt malfunction?

Shunt series - 30%

Head CT - 61%

Lower than I expected. Suggests that patients presenting with a history and physical suggestive of possible shunt malfunction need specialty consultation despite normal imaging studies.

Source

Mater, A. "Test characteristics of neuroimaging in the emergency department evaluation of children for cerebrospinal fluid shunt malfunction." CJEM 1 Marc 2008.