A 10-year-old boy is brought to the emergency department via ambulance after he was involved in a motor vehicle collision. The patient is unconscious on arrival. Glasgow Coma Scale (GCS) score is 8. CT scan does not show any specific lesion. The patient remains unconscious for the next 7 hours. Based on these findings, which of the following is the most likely diagnosis?

Rationale: A. Epidural hematomas often present with a “lucid interval,” where the patient initially loses consciousness, briefly regains it, and then deteriorates rapidly. CT imaging typically shows a biconvex (lens-shaped) hematoma. In this case, CT was normal, and the patient remained unconscious, making epidural hematoma less likely. B. Subarachnoid hemorrhage usually presents with sudden severe headache, nausea, vomiting, and neurological deficits. CT scans are generally positive in acute cases. The absence of CT findings and persistent unconsciousness make this diagnosis unlikely. C. Subdural hematomas can present with delayed symptoms, but they are usually visible on CT imaging as crescent-shaped lesions. A normal CT scan reduces the likelihood of an acute subdural hematoma. D. Diffuse axonal injury (DAI) results from shearing forces during high-velocity trauma, causing widespread damage to axons. DAI often leads to prolonged unconsciousness without specific findings on initial CT scans. The patient’s persistent coma, GCS ≤8, and normal CT are classic features of DAI. MRI may later reveal axonal injury not visible on CT.