Persistent coagulopathy after gunshot traumatic brain injury: the importance of INR and the SPIN score

Introduction Penetrating ballistic brain injury (gunshot traumatic brain injury or GTBI) is associated with a high mortality. Admission Glascow Coma Scale (GCS), injury severity score and neurological findings, cardiopulmonary instability, coagulopathy and radiological finding such as bullet trajectory and mass effect are shown to predict survival after GTBI. We aimed to examine the dynamics of the observed coagulopathy and its association with outcome. Methods In this single-centered retrospective cohort study, we examined 88 patients with GTBI between 2015 and 2021. Variables analyzed include patient age; temperature, hemodynamic and respiratory variables, admission Glasgow Coma Scale (GCS); injury severity score (ISS); head abbreviated injury scale (AIS); Marshall, Rotterdam, SPIN and Baylor scores, and laboratory data including PTT, INR and platelet count. Receiver operating characteristic analysis was conducted to evaluate the performance of the predictive models. Results The average age of our sample was 28.5 years and a majority were male subjects (92%). Fifty-four (62%) of the patients survived to discharge. The GCS score, as well as the motor, verbal, and eye-opening sub-scores were higher in survivors (P < 0.001). As was expected, radiologic findings including the Marshall and Rotterdam Scores were also associated with survival (P < 0.001). Although the ISS and Head AIS scores were higher (P < 0.001), extracranial injuries were not more prevalent in non-survivors (P= 0.567). Non-survivors had lower platelet counts and elevated PTT and INR (P < 0.001) on admission. PTT normalized within 24 h but INR continued to increase in non-survivors. SPIN score, which includes INR, was a better predictor for mortality than Rotterdam, Marshall, and Baylor etc. Conclusion Progressively increasing INR after GTBI is associated with poor outcome and may indicate consumption coagulopathy from activation of the extrinsic pathway of coagulation and metabolic derangements that are triggered and sustained by the brain injury. The SPIN score, which incorporates INR as a major survival score component, outperforms other available prediction models for predicting outcome after GTBI.