This article includes discussion of headache attributed to disorder of homeostasis, headache associated with decompression illness, headache associated with dialysis, headache associated with hypercapnia, headache associated with hypoglycemia, headache associated with arterial hypertension, cardiac cephalalgia, high altitude headache, and hypoxic headache. The foregoing terms may include synonyms, similar disorders, variations in usage, and abbreviations.
Homeostasis refers to the concept that organisms must adjust to external stimuli so that internal conditions remain stable. Multiple medical problems that upset this equilibrium may cause headache. This updated article on headaches attributed to disorders of homeostasis reviews both medical conditions, such as arterial hypertension or hypothyroidism, and external factors, such as high altitude or fasting, which commonly produce headache. Among the updates are evidence-based treatments for high altitude headache, new insights into life-threatening disorders such as autonomic dysreflexia and cardiac cephalalgia, and a review of newly classified disorders such as airplane and space headache.
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• Dexamethasone, analgesics, and preventive acetazolamide are among the effective treatments for high altitude headache.
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• Hypertensive encephalopathy may trigger headache in association with arterial hypertension (> 180/120 mm Hg), especially in those with pheochromocytoma.
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• Autonomic dysreflexia, often triggered by bladder or bowel problems, may trigger severe headache, tachycardia, hypertension, coma, and death if untreated.
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• Fasting is a trigger for migraine, even in the absence of hypoglycemia. Preemptive frovatriptan may prevent migraine triggered by fasting.
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• Myocardial ischemia may trigger migraine-like headache, usually aggravated by exercise and relieved by treatment of angina.
Historical note and terminology
Headache attributed to a disorder of homeostasis as defined by classification from the International Headache Society (44) includes headaches that occur during a metabolic disturbance and disappear after normalization of the metabolic state. The major disorders of homeostasis known to cause headache include hypoxia and/or hypercapnia, hemodialysis, arterial hypertension, hypothyroidism, fasting, and cardiac cephalalgia.
This review does not consider headaches attributed to inflammatory or autoimmune disorders, infection, vascular disorders, seizures, increased or low cerebrospinal fluid pressure, and headache related to substances that may cause headache or withdrawal.