GCS 15: when mild TBI isn't so mild

The present study characterizes patients with the mildest of mild traumatic brain injury (TBI), as defined by a Glasgow coma score (GCS) of 15.

This is an IRB approved observational cohort study of adult patients who presented to the emergency department of a Level-1 trauma center, with the primary diagnosis of TBI and a GCS score of 15 on arrival. Data collected included demographic variables such as age, gender, race, mechanisms of injury, signs and symptoms including associated vomiting, seizures, loss of consciousness (LOC), alteration of consciousness (AOC), and post-traumatic amnesia (PTA).Pre- hospital GCS, Emergency Department (ED) GCS, and results of brain CT scans were also collected as well as patient centered outcomes including hospital or intensive care unit (ICU) admission, neurosurgical intervention, and in hospital death. Data were stored in REDCap (Research Electronic Data Capture), a secure, web- based application. Descriptive and inferential analysis was done using JMP 14.0 for the Mac.

Univariate predictors of hospital admission included LOC, AOC, and PTA, all p < 0.0001. Patients admitted to ICU were significantly more likely to be on an antiplatelet or anticoagulant (P < 0.0001), have experienced PTA (p = 0.0025), LOC (p < 0.0001), or have an abnormal brain CT (p < 0.0001). Patients who died in the hospital were significantly more likely to be on an antiplatelet or anticoagulant (P = 0.0005. All who died in the hospital had intracranial hemorrhage on ED head CT, despite having presented to the ED with GCS of 15. Patients were also significantly more likely to have had vomiting (p < 0.0001). Patients who underwent neurosurgical intervention were significantly more likely to be male (P = 0.0203), to be on an antiplatelet or anticoagulant (P = < 0.0001) likely to have suffered their TBI from a fall (P = 0.0349), and experienced vomiting afterwards (P = 0.0193).

This study underscores: 1) the importance of neuroimaging in all patients with TBI, including those with a GCS 15. Fully 10% of our cohort was not imaged. Extrapolating, these would represent 2.5% bleeds, and 1.47% fractures. 2) The limitations of GCS in classifying TBI, as patients with even the mildest of mild TBI have a high frequency of gross CT abnormalities.