Final answer:
Difficulty swallowing is a sign that brainstem involvement occurred during the surgical procedure.
Step-by-step explanation:
The sign that would indicate brainstem involvement during the surgical procedure is Difficulty swallowing. The brainstem is responsible for controlling various functions including swallowing. Damage or involvement of the brainstem can cause difficulty in swallowing. This sign should be monitored by the nurse to ensure appropriate care for the child.