Transcranial Sonographic Assessment of the Third Ventricle in Neuro-ICU Patients to Detect Hydrocephalus: A Diagnostic Reliability Pilot Study

BACKGROUND: Transcranial sonography is a point of care tool recommended in intensive care units (ICU) to monitor brain injured patients. OBJECTIVE: To assess feasibility and reliability of the third ventricle (V3) diameter measurement using transcranial sonography (TCS) compared to brain computedtomography (CT), the gold standard measurement, and to measure the TCS learning curve. METHODS: prospective study, in a 16-bed neurological ICU in an academic hospital. We included consecutive brain injured adult patient, who required a brain CT and TCS monitoring. V3 diameter was blindly measured by TCS and CT. MAIN OUTCOME MEASURES: V3 diameter measured by TCS and CT: Intra-class correlation coefficient (ICC) and Bland-Altman plot were used to assess the reliability and agreement between V3 measurements. Diagnosis performance of the V3 diameter using TCS to detect hydrocephalus was measured. Absolute difference between V3 measurement by residents and experts was measured consecutively to assess the learning curve. RESULTS: Among the 100 patients included in the study, V3 diameter could be assessed in 87 patients from at least one side of the skull. Both temporal windows were available in 70 patients. The ICC between V3 diameter measured by TCS and CT was 0.90 [95% Confidence-Interval 0.84-0.93] on the right side, and 0.92 [0.880.95] on the left side. In Bland-Altman analysis, mean difference, standard deviation, 95% limits of agreement were 0.36, 1.52, -2.71 to 3.45 mm, respectively, on the right side; 0.25, 1.47, -2.71 to 3.21 mm, respectively, on the left side. Among the 35 patients with hydrocephalus, V3 diameters could be measured by TCS in 31 patients from at least one side. Hydrocephalus was respectively excluded, confirmed, or inconclusive using TCS in 40, 29 and 31% of the 87 assessable patients. After 5 measurements, every resident reached a satisfactory measurement compared to the expert operator, defined by a mean absolute difference < 1 mm. CONCLUSION: TCS allows rapid, simple and reliable V3 diameter measurement compared with the gold standard in neuro-ICU patients. Aside from sparing irradiating procedures and transfers to the radiology department, it may especially increase close patient monitoring to detect clinically occult hydrocephalus earlier. Further studies are needed to measure potential clinical benefit. TRIAL REGISTRATION: ClinicalTrials.gov ID: NCT02830269. Registered 17 July 2016, https://www.clinicaltrials.gov/ct2/show/NCT02830269?term=NCT02830269&draw=2&rank=1