Predicting the Risk of Uncal Herniation Based on Brain CT in Patients with Traumatic Brain Injury: A Novel Ratio

Abstract We hypothesized that individuals with smaller tentorial hiatus may be at higher risk of uncal herniation, especially in the setting of traumatic brain injury (TBI). However, currently there is no way of predicting which individuals are at increased risk of uncal herniation from the head computed tomography (CT) done at admission in patients with head injury. The aim of the study was to assess the usefulness and reliability of a new ratio (inter-clinoidal distance to inter-tentorial distance [ICD/ITD] ratio) in predicting individuals at higher risk of uncal herniation on head CT. This was a prospective study done in our department over 2 months (August to October 2024). The brains of all patients with severe TBI (Glasgow coma scale [GCS] <9) who were admitted under neurosurgery and died in-hospital were removed during autopsy to see for uncal herniation. The head CT scans at admission of these patients were also evaluated and the ICD/ITD ratio was calculated for all. A total of 17 patients with severe TBI died during the study period and autopsy was performed on them. Of these, 12 did not show signs of any uncal herniation. Five patients had uncal herniation. The average ICD/ITD ratio was 0.97 ± 0.08 in patients without uncal herniation as compared to an average ICD/ITD ratio of 1.67 ± 0.42 in patients with uncal herniation Our method provides a simple and practical way to assess the tentorial hiatus on the head CT using the novel ICD/ITD ratio. An ICD/ITD ratio above 1.2 indicates higher risk of uncal herniation in patients with TBI.