Final answer:
The most appropriate nursing action for a patient recovering from intracranial surgery and complaining of a severe headache is to assess vital signs and neurologic status, administer pain medication, and provide comfort measures.
Step-by-step explanation:
The most appropriate nursing action for a patient recovering from intracranial surgery and complaining of a severe headache is to assess the patient's vital signs and neurologic status, administer pain medication as ordered, and provide comfort measures. It is important to monitor the patient closely for any signs of increased intracranial pressure, such as changes in level of consciousness, pupil size and reactivity, or motor function. If the headache persists or worsens, the nurse should notify the healthcare provider for further evaluation and possible intervention.