Photic sneeze reflex

Photic sneeze reflex (also whimsically called ACHOO, a backronymfor 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 humanswith more common occurrence in Caucasiansthan other human races. The condition is passed along geneticallyas an autosomal dominanttrait.

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 nervesignals in the trigeminal nervenucleus. 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 nervetriggers the trigeminal nerve, and this causes the photic sneeze reflex. Another theory suggests that tears leaking into the nose through the nasolacrimal ductare 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.

The photic sneeze reflex is considered a risk factor to combatpilots: people suffering from photic sneeze reflex may not fly combat aircraft.

References

• 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 photic response to bright light. Is it a cause of accidents?" The Guthrie Journal, 1995, 64(3):104-105
• Semes LP, Amos JF, Waterbor JW. "The Photic Sneeze Response: Descriptive Report of a Clinic Population." Journal of American Optometry Association June 1995, 66(6):372-377 [On-line], PMID 7673597
• Breitenbach, R.A, "The Photic Sneeze Reflex as a Risk Factor to Combat Pilots." Military Medicine, December 1993, 158:806-809, PMID 8108024.

External links

• OMIM100820
• MadSci article on the photic sneeze reflex
• Scientific American notes on the photic sneeze reflex
• Annotated biography on medical journals on the photic sneeze reflex
• The Straight Dope on photic sneeze reflex
• The Naked Scientists discussing the photic sneeze reflexde:Photischer Niesreflex

es:Reflejo de estornudo por luz brillante

This article is licensed under the GNU Free Documentation License.
It uses material from the http://en.wikipedia.org/wiki/Photic+sneeze+reflex Wikipedia article Photic sneeze reflex.