What is a common sign of severe head injury?

Dilated pupils are a common sign of severe head injury due to increased intracranial pressure, which can occur as a result of traumatic brain injury, bleeding within the skull, or swelling of brain tissue. This condition affects the cranial nerves responsible for pupil size and reaction. When the brain is injured, particularly in areas that control vision and pupil response, the pupils may become dilated and non-reactive to light. This can serve as a critical indicator of the severity of the head injury and the need for immediate medical attention.

In contrast, increased heart rate, hyperactive reflexes, and normal blood pressure do not specifically indicate severe head injury. While they may be associated with various medical conditions or stress responses, they lack the direct connection to the pathophysiology of severe head trauma that dilated pupils signify. Understanding symptoms like this is crucial for properly assessing and managing potential head injuries in trauma situations.