A patient presents to the emergency department after an assault with a bat to his chest. Pulmonary contusion can lead to death due to which of the following mechanisms?

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.

Rationale:

A. Concussion presents with a range of neurologic symptoms including headache, dizziness, confusion, drowsiness, nausea, vomiting, and visual disturbances. These are key indicators for clinical assessment.

B. Concussions are typically diagnosed clinically through history and neurologic examination. CT scans are often normal and are used primarily to rule out more serious brain injuries, such as intracranial hemorrhage or skull fractures, rather than to confirm a concussion.

C. Concussions usually result from a blunt impact or rapid acceleration-deceleration of the head, causing transient brain dysfunction. Common mechanisms include falls, sports injuries, motor vehicle collisions, and assaults.

D. Concussions are generally classified based on severity: mild (brief confusion, no loss of consciousness) or classic (loss of consciousness lasting less than 6 hours and post-traumatic amnesia less than 24 hours).

E. Most concussions are mild to moderate and resolve with rest and monitoring. Severe traumatic brain injury is a distinct condition involving structural brain damage, prolonged loss of consciousness, or significant neurologic deficits.

F. Patients with concussion should be monitored for any worsening symptoms, such as repeated vomiting, severe headache, increasing confusion, slurred speech, or neurologic deficits, which may indicate a more serious injury requiring immediate medical attention.