Objective:

NA

Background:

Diffuse axonal injury (DAI) is a form of traumatic brain injury resulting from shearing forces, classically associated with prolonged coma, poor prognosis, and characteristic MRI findings. Grade III DAI, involving the brainstem, is particularly linked to severe and often irreversible neurologic dysfunction. However, fat embolism syndrome (FES)—a condition characterized by fat droplet embolization following trauma or orthopedic injury—can present with similar neurologic findings and imaging features, creating diagnostic uncertainty with critical management implications.

Design/Methods:

NA

Results:

A healthy 23-year-old male presented after a high-speed motorcycle crash with long bone fractures and a Glasgow Coma Scale (GCS) of 14. He was alert, oriented, and interactive in the emergency department and remained neurologically intact through early hospitalization. Roughly 28 hours post-admission, he acutely developed altered mental status, gaze deviation, and hemodynamic instability requiring vasopressors and intubation. MRI brain revealed punctate diffusion restriction and FLAIR hyperintensities at the gray-white junction and brainstem—concerning for Grade III DAI. However, this was discordant with his previously intact mentation. Over the subsequent days, he developed anemia, thrombocytopenia, and pulmonary embolism. The clinical triad of respiratory compromise, neurologic symptoms, and hematologic abnormalities raised concern for FES. With supportive care and orthopedic surgery, the patient improved neurologically, was extubated on hospital day 8, and discharged to inpatient rehabilitation at near-baseline function.

Conclusions:

This case illustrates how FES can mimic severe DAI both clinically and radiographically. Early improvement followed by neurologic decline is atypical for Grade III DAI but consistent with evolving FES. In trauma patients with high-risk fractures and atypical neuroimaging correlations, FES should remain on the differential—even without a petechial rash. Recognizing this distinction can drastically alter prognosis and guide appropriate clinical decision-making.