What symptom may indicate brain herniation following a head injury?

Loss of the gag reflex can be a significant indicator of brain herniation following a head injury. This symptom suggests impairment of cranial nerve function, specifically the glossopharyngeal and vagus nerves, which are responsible for the reflexive response of gagging. When brain tissue is displaced due to increased intracranial pressure as a result of swelling or mass effect, it can compress vital structures, including those responsible for controlling autonomic reflexes. The gag reflex is crucial for protecting the airway; its loss can indicate the severity of brain injury and may precede further neurological deterioration.

While blurred vision, increased irritability, and severe headache are also concerning symptoms that can occur after a head injury, they do not specifically indicate brain herniation. Blurred vision may arise from various causes, including concussion or increased intracranial pressure but isn't as definitive. Increased irritability can be a general sign of discomfort or distress in young children but lacks specificity for brain herniation. Severe headache is common after head trauma, though it does not directly correlate with brain herniation without additional neurological signs. Thus, loss of the gag reflex serves as a more clear signal of potential herniation due to its direct connection to brainstem function and neurological