Radiographic markers of clinical outcomes after endoscopic third ventriculostomy with choroid plexus cauterization: cerebrospinal fluid turbulence and choroid plexus visualization
Authors: Pindrik Jonathan , Rocque Brandon G. , Arynchyna Anastasia A. , Johnston James M. , Rozzelle Curtis J. 
Published: May 2016

OBJECTIVE
Endoscopic third ventriculostomy (ETV) with choroid plexus (CP) cauterization (CPC) represents a viable treatment option for congenital hydrocephalus in infants younger than 2 years. Imaging studies complement clinical data in the evaluation of treatment success or failure. The objectives of this study were to investigate novel radiographic markers—cerebrospinal fluid (CSF) turbulence and CP visualization—and their ability to reflect or predict clinical outcomes following ETV/CPC.

METHODS
Hydrocephalic patients younger than 2 years who were initially treated by ETV/CPC at the senior authors' institution between March 2013 and February 2014 were retrospectively reviewed. Clinical data, as well as the visualization of CSF turbulence and CP on pre- and postoperative fast-sequence MRI, were recorded. Radiographic images were reviewed by a blinded observer based on specific criteria for the visualization of CSF turbulence and CP. Data were collected and analyzed using descriptive statistics, including Fisher's exact test for comparisons. The research team obtained appropriate institutional review board approval for this study, without the need for informed consent.

RESULTS
Among the 32 patients (53% male and 47% female) studied, 18 of 32 (56%) responded favorably to initial or repeat ETV/CPC, with 13 of 32 (41%) patients requiring 1 surgery. Of the 19 (59%) patients whose initial ETV/CPC failed, 8 of 19 (42%) patients underwent repeat ETV/CPC, with 5 of 8 (63%) patients responding favorably. Radiographic CSF turbulence appeared more frequently following ETV/CPC failure than after ETV/CPC success (55% vs 18%, respectively; p = 0.02). The sensitivity and specificity of CSF turbulence as a radiographic marker for ETV/CPC failure were 80% and 58%, respectively. The radiographic depiction of CP disappearance following ETV/CPC from pre- to postoperative imaging occurred in 20 of 30 patients (67%). Among the patients who responded unsuccessfully to ETV/CPC and ultimately required secondary shunt insertion, 71% (10 of 14 patients) demonstrated CP persistence on postoperative imaging. In contrast, 6% (1 of 18) of patients who were treated successfully by ETV/CPC demonstrated the presence of CP on follow-up imaging. This difference reached statistical significance (p = 0.0001). The visualization of CP persistence despite ETV/CPC reflected treatment failure with 91% sensitivity and 81% specificity. The sensitivity of either or both radiographic markers to suggest ETV/CPC failure was 77%, while their specificity (both markers absent, thereby indicating ETV/CPC success) was 81%.

CONCLUSIONS
Radiographic markers correlate with clinical outcomes following the treatment of infantile hydrocephalus with ETV/CPC. Specifically, CSF turbulence may indicate ongoing pathological CSF flow dynamics, while CP absence following ETV/CPC may predict shunt independence. Future studies that incorporate prospective review and formal intra- and interobserver reliability estimates may help corroborate the utility of these radiographic markers.