Photic sneeze reflex

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-->Photic sneeze reflex (also referred to as sun sneezing, photogenic sneezing, or whimsically called ACHOO, a backronym for Autosomal dominant Compelling Helio-Ophthalmic Outburst) is a medical condition by which people exposed to bright light sneeze. It has been suggested that the photic sneeze reflex occurs only after someone has been adapted to the dark for at least five minutes, although this is not certain, and is not uniform amongst people with the photic sneeze reflex. The photic sneeze reflex can also cause one to sneeze many times consecutively. The condition occurs in 17% to 25% of humans with more common occurrence in Caucasians than other human races. The condition is passed along genetically as an autosomal dominant trait.

The first mention of the phenomenon is probably in the later work attributed to Aristotle (Problems, book XXXIII).

The probable cause is a congenital malfunction in nerve signals in the trigeminal nerve nucleus. The fifth cranial nerve, called the trigeminal nerve, is apparently responsible for sneezes. Research suggests that some people have an association between this nerve and the nerve that transmits visual impulses to the brain. Overstimulation of the optic nerve triggers the trigeminal nerve, and this causes the photic sneeze reflex. Another theory suggests that tears leaking into the nose through the nasolacrimal duct are a cause of the photic sneeze reflex. The speed of the reflex seems to favour the first theory, as it happens much too quickly for tears to be generated and drain into the nose. In addition this sneeze reflex can be brought on by a sudden inhaling of cold air or a strong flavor such as a strong mint gum. This implies an overstimulation of any nerve close to the trigeminal nerve can cause the sneeze reflex.

References

Beckman L, Nordenson I. "Individual differences with respect to the sneezing reflex: an inherited physiological trait in man?." Hum Hered. 1983, 33(6):390-1, PMID 6674114.
Breitenbach RA, "The photic sneeze reflex as a risk factor to combat pilots." Mil Med. Dec 1993, 158:806-9, PMID 8108024.
Collie WR, Pagon RA, Hall JG, Shokeir MH. "ACHOO syndrome (autosomal dominant compelling helio-ophthalmic outburst syndrome)." Birth Defects Orig Artic Ser. 1978, 14(6B):361-3, PMID 728575.
Deshmukh N. "Sneezing response to bright light. Is it a cause of accidents?" The Guthrie Journal. 1995, 64(3):104-5.
Everett HC. "Sneezing in response to light." Neurology. 1964, 14:483-90, PMID 14144120.
Forrester JM. "Sneezing on exposure to bright light as an inherited response." Hum Hered. 1985, 35:113-4, PMID 3988295.
Morris HH 3rd. "ACHOO syndrome: prevalence and inheritance." Clev Clin J Med. 1987, 54:431-3, PMID 3665024.
Peroutka SJ, Peroutka LA. "Autosomal dominant transmission of the 'photic sneeze reflex.'" N Engl J Med. Mar 1 1984, 310(9):599-600, PMID 6694722.
Semes LP, Amos JF, Waterbor JW. "The photic sneeze response: descriptive report of a clinic population." J Am Optom Assoc. June 1995, 66(6):372-7, PMID 7673597.
Whitman BW, Packer RJ. "The photic sneeze reflex: literature review and discussion." Neurology. May 1993, 43(5):868-71, PMID 8492938.

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