Table 2.

Differential diagnosis of NDPH.

Item	Presence of:	Consider Other Conditions:
Headache History	Previous history of primary headache Absence of trigger factor	Worsening of primary headache
	Excessive use of drugs for the attacks	Considering MOH
	Head or neck trauma	Headache secondary to trauma
	Worsening with Valsalva, or changes in posture	Altered CSF pressure
	Pain lasting 15 to 180 min	Cluster headache
	Pain lasting 2 to 30 min	Paroxysmal hemicrania
Neurological Exam	Focal sign Altered consciousness	Secondary cause of headache (i.e., vascular disorders, altered CSF pressure, neoplasia, CNS infections)
General examination	Fever	Secondary cause of headache (i.e., CSN infections)
	Prominent cranial parasympathetic autonomic features	TACs
Fundus oculi	Papilledema	Idiopathic intracranial hypertension Other secondary causes of headache.
Drug Response	Indomethacin *	Hemicrania Continua

MOH: Medication Overuse Headache; CSN: central nervous system; TACs: Trigeminal Autonomic Cephalalgias; CSF: Cerebrospinal fluid. * The indomethacin dosage necessary for successful treatment ranges from 25 to 300 mg per day, with an average of 100 mg per day. The beneficial effects appear within two days (range, one to five days). On discontinuation, headache reappears in about three days (range, 1 to 14 days).