A nurse is teaching the parents of a 12-year-old patient who was diagnosed with a concussion after a fall. Which of the following signs and symptoms should the parents report immediately if observed?

A concussion is a mild traumatic brain injury resulting from rapid acceleration-deceleration forces causing neuronal dysfunction, impaired cerebral glucose metabolism, and transient disruption of cortical and brainstem regulation. Deterioration after head injury may indicate evolving intracranial hemorrhage or increased intracranial pressure (ICP) requiring urgent escalation. Rationale: A. Vision 20/25 is within normal functional visual acuity limits for a 12-year-old. It does not indicate neurological deterioration or increased ICP. This finding is stable and does not require urgent reporting in post-concussion monitoring. B. Slight bruising on the forehead reflects superficial soft tissue trauma from the initial impact. It does not indicate intracranial injury progression. External bruising alone without neurological decline is not an emergency warning sign. C. Occasional yawning may reflect fatigue or post-concussive tiredness due to transient cerebral dysfunction. It is nonspecific and not independently associated with increased ICP or neurological deterioration requiring urgent intervention. D. Short-term memory loss is a common expected post-concussion symptom due to temporary disruption of hippocampal function. While it should be monitored, it is not an acute red flag unless it is worsening or accompanied by other neurologic signs. E. Nausea and vomiting are critical warning signs of rising intracranial pressure or possible intracranial bleeding. They suggest worsening cerebral edema or brain irritation and require immediate medical evaluation and escalation of care. F. Blurred vision indicates possible increased intracranial pressure or cranial nerve involvement affecting visual pathways. This is a neurological red flag suggesting potential deterioration of brain function and requires urgent assessment and prompt intervention.