PURPOSE: A patency at the cochlear basal turn (CBTP) can lead to an abrupt leakage of CSF, known as intraoperative CSF gusher. To date, there is no established technique for predicting an intraoperative CSF gusher. We aim to establish the prevalence, width and anatomical variation of CBTP in patients with and without hearing loss as well as to estimate its association between intraoperative CSF gusher. METHODS: A retrospective review of high-resolution CT images and medical records from 165 pediatric patients (330 ears) was conducted (57 males/108 females). Patients were grouped based on audiometry results: a hearing loss group and healthy controls. The presence and size of CBTP was assessed using multiplanar reconstruction techniques. The incidence of intraoperative CSF gusher was recorded and correlated with the width of CBTP. RESULTS: Cochlear basal turn patency was found in 44.2% of ears without significant differences between both groups (p = 0.06). Intraoperative CSF gusher occurred in 5.1% of cases, more frequently in ears with inner ear malformations (27.3%). A CBTP larger than 0.75 mm did not predict intraoperative CSF gusher (p = 0.55). Enlarged vestibular aqueduct was significantly the more common malformation in patients with intraoperative CSF gusher (p <
0.01). CONCLUSION: Intraoperative CSF gusher highlights the need for reliable imaging predictors. Yet, CBTP alone does not predict this phenomenon, indicating other contributing factors beyond known imaging findings.