For example, a person with signs of hyposalivation may not complain of xerostomia. Conversely a person who reports experiencing xerostomia may not show signs of reduced salivary secretions (subjective xerostomia). In the latter scenario, there are often other oral symptoms suggestive of oral dysesthesia ("burning mouth syndrome"). Some symptoms outside the mouth may occur together with xerostomia. These include:

Xerophthalmia (dry eyes). Inability to cry. Blurred vision. Photophobia (light intolerance). Dryness of other mucosae, e.g., nasal, laryngeal, and/or genital. Burning sensation. Itching or grittiness. Dysphonia (voice changes).There may also be other systemic signs and symptoms if there is an underlying cause such as Sjögrens syndrome, for example, joint pain due to associated rheumatoid arthritis. Cause
The differential of hyposalivation significantly overlaps with that of xerostomia. A reduction in saliva production to about 50% of the normal unstimulated level will usually result in the sensation of dry mouth. Altered saliva composition may also be responsible for xerostomia. Physiologic
Salivary flow rate is decreased during sleep, which may lead to a transient sensation of dry mouth upon waking. This disappears with eating or drinking or with oral hygiene. When associated with halitosis, this is sometimes termed "morning breath". Dry mouth is also a common sensation during periods of anxiety, probably owing to enhanced sympathetic drive. Dehydration is known to cause hyposalivation, the result of the body trying to conserve fluid. Physiologic age-related changes in salivary gland tissues may lead to a modest reduction in salivary output and partially explain the increased prevalence of xerostomia in older people.
It was believed to work via "letting evil spirits escape". William Harvey recommended trepanation as a treatment for migraines in the 17th century.While many treatments for migraine have been attempted, it was not until 1868 that use of a substance which eventually turned out to be effective began. This substance was the fungus ergot from which ergotamine was isolated in 1918. Methysergide was developed in 1959 and the first triptan, sumatriptan, was developed in 1988. During the 20th century with better study-design, effective preventive measures were found and confirmed. Society and culture
Migraine is a significant source of both medical costs and lost productivity. It has been estimated that migraine is the most costly neurological disorder in the European Community, costing more than €27 billion per year. In the United States, direct costs have been estimated at $17 billion, while indirect costs — such as missed or decreased ability to work — is estimated at $15 billion. Nearly a tenth of the direct cost is due to the cost of triptans. In those who do attend work during a migraine attack, effectiveness is decreased by around a third. Negative impacts also frequently occur for a persons family. Research
Potential prevention mechanisms
Transcranial magnetic stimulation shows promise as does transcutaneous supraorbital nerve stimulation. There is preliminary evidence that a ketogenic diet may help prevent episodic and long-term migraine.