出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2013/12/03 22:59:22」(JST)
| Ice-cream headache | |
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| Classification and external resources | |
The trigeminal nerve, shown in yellow, conducts signals from dilating blood vessels in the palate to the brain, which interprets the pain as coming from the forehead.
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| ICD-10 | G44.8021 (ICD-10NA) |
An ice-cream headache, also known as brain freeze, cold-stimulus headache,[1] or its given scientific name sphenopalatine ganglioneuralgia (meaning "nerve pain of the sphenopalatine ganglion"-and is also considered a misnomer since the pain nerves have nothing to do with the sphenopalatine/pterygopalatine ganglion, but travel along the trigeminal nerves described below), is a form of brief cranial pain or headache commonly associated with consumption (particularly quick consumption) of cold beverages or foods such as ice cream and ice pops. It is caused by having something cold touch the roof of the mouth (palate), and is believed to result from a nerve response causing rapid constriction and swelling of blood vessels[2] or a "referring" of pain from the roof of the mouth to the head.[3][4] The rate of intake for cold foods has been studied as a contributing factor.[5][6]
The term ice-cream headache has been in use since at least 31 January 1937, contained in a journal entry by Rebecca Timbres published in the 1939 book We didn't ask Utopia: a Quaker family in Soviet Russia.[7] The first published use of the term brain freeze, as it pertains to cold-induced headaches, was on 27 May 1991.[8]
"Ice cream headaches" result from quickly eating or drinking very cold substances. It is commonly experienced when applying ice-cream (or similar) to the roof of the mouth (palate) or when swallowing it.[9] Typically, the headache appears in about 10 seconds and lasts about 20 seconds, though some people experience much longer lapses of pain; the pain seems to relate to the same side of the head, as the cold substance was applied to the palate, or to both sides of the head in the case of swallowing.[9] The most effective way to prevent it is to consume the cold food or liquid at a slower rate. Keeping it in one's mouth long enough for the palate to become used to the temperature is also an effective preventative.
An ice cream headache is the direct result of the rapid cooling and rewarming of the capillaries in the sinuses. A similar but painless blood vessel response causes the face to appear "flushed" after being outside on a cold day. In both instances, the cold temperature causes the capillaries in the sinuses to constrict and then experience extreme rebound dilation as they warm up again.[10]
In the palate, this dilation is sensed by nearby pain receptors, which then send signals back to the brain via the trigeminal nerve, one of the major nerves of the facial area. This nerve also senses facial pain, so as the neural signals are conducted the brain interprets the pain as coming from the forehead—the same "referred pain" phenomenon seen in heart attacks. Brain-freeze pain may last from a few seconds to a few minutes. Research suggests that the same vascular mechanism and nerve implicated in "brain freeze" cause the aura (sensory disturbance) and pulsatile (throbbing pain) phases of migraines.[11]
It is possible to suffer from an ice-cream headache in both hot and cold weather, because the effect relies upon the temperature of the food being consumed rather than that of the environment.
Another theory into the cause of ice-cream headaches is explained by increased blood flow to the brain through the anterior cerebral artery, which supplies oxygenated blood to most medial portions of the frontal lobes and superior medial parietal lobes. This increase in blood volume and resulting increase in size in this artery is thought to bring on the pain associated with an ice-cream headache.
When the anterior cerebral artery constricts, reining in the response to this increased blood volume, the pain disappears. The dilation, then quick constriction, of this blood vessel may be a type of self-defense for the brain.
This inflow of blood cannot be cleared as quickly as it is coming in during the ice-cream headache, so the blood flow could raise the pressure inside the skull and induce pain that way. As the intracranial pressure and temperature in the brain rise the blood vessel contracts, and the pressure in the brain is reduced before reaching dangerous levels.[12]
To relieve pain, some doctors suggest pressing the tongue against the roof of the mouth to warm the area[13] or tilting the head back for about 10 seconds. Another method to relieve ice cream headaches is to drink a liquid that has a higher temperature than the substance that caused the ice cream headache. Some people report relief by breathing in through the mouth and out through the nose, thus passing warm air through the nasal passages.
The phenomenon is common enough to have been the subject of research published in the British Medical Journal and Scientific American.[10][11] A study conducted by Maya Kaczorowski demonstrated a higher incidence of sphenopalatine ganglioneuralgia in subjects consuming the ice cream sample in less than 30 seconds vs. those who consumed slowly, with no time limit (27.3% and 12.5% respectively). However, Kaczorowski was ultimately not able to draw a clear connection between the speed of consumption and incidence of sphenopalatine ganglioneuralgia.[14]
The International Classification of Headache Disorders (ICHD) code is 13.11.2 and International Statistical Classification of Diseases and Related Health Problems ICD-10NA code is G44.8021, "Headache attributed to ingestion or inhalation of a cold stimulus".[15]
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| リンク元 | 「アイスクリーム頭痛」 |
| 関連記事 | 「cream」「icing」「ice」 |