Acute headache in the emergency department.

In the acute setting, the primary objective is to decide whether the headache is primary, secondary but benign (for example a headache associated with a cold), or secondary to a potentially life-threatening cause (subarachnoid hemorrhage (SAH), bacterial meningitis, intracranial hypertension). The cornerstone of headache diagnosis is the interview with the patient, followed by a thorough physical examination. These two first clinical steps determine the need for investigation, immediate with inpatient care or on an outpatient basis, and the treatment to recommend, acutely and for future attacks in the case of primary headache. The indication for referral to a neurologist for long-term follow-up is assessed. Headaches can be separated into four groups: (1) recent onset and thunderclap; (2) recent onset with progressive installation: (3) well known to the patient and episodic (attacks with headache-free periods, as in episodic migraine or cluster headache); and (4) chronic daily headaches (more than 3 months, more than 15 days of headache per month). Headaches with a recent onset and judged unusual or worrisome by the patient (even one with frequent headaches) must raise the suspicion of a secondary cause and need to be investigated. Headaches that continue for months or years are more often primary, but secondary causes need to be ruled out in certain cases.