A Rare Cause of Chronic Headache that May Be Misdiagnosed as Migraine: Chronic Carbon Monoxide Poisoning Migren ile Karişabilen Nadir bir Kronik Baş Ağrisi Nedeni: Kronik Karbon Monoksit Zehirlenmesi

SUMMARY Differential diagnosis of primary headache disorders can be challenging for physicians. Although the association of headache with acute carbon monoxide intoxication is very well-defined, in refrac tory nonspecific headaches associated with chronic low dose ex posure to carbon monoxide, CO intoxication is usually overlooked, mostly due to vague symptoms. Herein we present a 15-year-old female patient with chronic carbon monoxide poisoning who was undergoing two years of follow-up care for migraines. Chronic carbon monoxide intoxication may mimic the episodic nature and familial predisposition of migraine attacks. Normal carboxyhemoglobin levels do not exclude the diagnosis, and smoking is a confounding factor. In emergency rooms, patients presenting with headaches had higher levels of carboxyhemoglobin, but, as far as we know, there have been no studies investigating carboxyhemoglobin levels in migraine patients. Chronic carbon monoxide poisoning should be suspected in migraine patients, especially if the attacks occur during winter months.