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Earwax

2007 Schools Wikipedia Selection. Related subjects: Health and medicine

   Wet-type human earwax on a cotton swab.
   Enlarge
   Wet-type human earwax on a cotton swab.

   Earwax, also known by the medical term cerumen, is a yellowish, waxy
   substance secreted in the ear canal of humans and many other mammals.
   It plays an important role in the human ear canal, assisting in
   cleaning and lubrication, and also provides some protection from
   bacteria, fungus, and insects. A comprehensive review of the physiology
   and pathophysiology of cerumen can be found in Roeser and Ballachanda.
   Excess or impacted cerumen can press against the eardrum and/or occlude
   the external auditory canal and impair hearing.

Production, composition, and different types

   Cerumen is produced in the outer third of the cartilaginous portion of
   the human ear canal. It is a mixture of viscous secretions from
   sebaceous glands and less-viscous ones from modified apocrine sweat
   glands. The primary components of earwax are the final products in the
   HMG-CoA reductase pathway, namely, squalene, lanosterol, and
   cholesterol.

   Two distinct genetically determined types of earwax are distinguished
   -- the wet type, which is dominant; and the dry type, which is
   recessive. Asians and Native Americans are more likely to have the dry
   type of cerumen (grey and flaky), whereas Caucasians and Africans are
   more likely to have the wet type (honey-brown to dark-brown and moist).
   Cerumen type has been used by anthropologists to track human migratory
   patterns, such as those of the Inuit.

   The difference in cerumen type has been tracked to a single base change
   (an SNP) in a gene known as " ATP-binding cassette C11 gene". In
   addition to affecting cerumen type, this mutation also reduces sweat
   production. The researchers conjecture that the reduction in sweat was
   beneficial to the ancestors of East Asians and Native Americans who are
   thought to have lived in cold climates.

Function

   Wet-type earwax fluoresces weakly under ultraviolet light.
   Enlarge
   Wet-type earwax fluoresces weakly under ultraviolet light.

Cleaning

   Cleaning of the ear canal occurs as a result of the "conveyor belt"
   process of epithelial migration, aided by jaw movement. Cells formed in
   the centre of the tympanic membrane migrate outwards from the umbo (at
   a rate equivalent to that of fingernail growth) to the walls of the ear
   canal, and accelerate towards the entrance of the ear canal. The
   cerumen in the canal is also carried outwards, taking with it any dirt,
   dust, and particulate matter that may have gathered in the canal. Jaw
   movement assists this process by dislodging debris attached to the
   walls of the ear canal, increasing the likelihood of its extrusion.

Lubrication

   Lubrication prevents desiccation and itching of the skin within the ear
   canal (known as asteatosis). The lubricative properties arise from the
   high lipid content of the sebum produced by the sebaceous glands. In
   wet-type cerumen at least, these lipids include cholesterol, squalene,
   and many long-chain fatty acids and alcohols.

Antibacterial and antifungal roles

   While studies conducted up until the 1960s found little evidence
   supporting an antibacterial role for cerumen, more recent studies have
   found that cerumen has a bactericidal effect on some strains of
   bacteria. Cerumen has been found to be effective in reducing the
   viability of a wide range of bacteria (sometimes by up to 99%),
   including Haemophilus influenzae, Staphylococcus aureus, and many
   variants of Escherichia coli. The growth of two fungi commonly present
   in otomycosis was also significantly inhibited by human cerumen. These
   antimicrobial properties are due principally to the presence of
   saturated fatty acids, lysozyme and, especially, to the relatively low
   pH of cerumen (typically around 6.1 in normal individuals).

Removal

   Excessive cerumen may impede the passage of sound in the ear canal,
   causing conductive hearing loss. It is also estimated to be the cause
   of 60 - 80% of hearing aid repairs. As mentioned above, movement of the
   jaw helps the ears' natural cleaning process, so chewing gum and
   talking can both help. If this is insufficient, the most common method
   of cerumen removal by general practitioners is syringing (used by 95%
   of GPs). A curette method is more likely to be used by otologists and
   ENTs when the ear canal is partially occluded and the material is not
   adhering to the skin of the ear canal.

Cerumenolysis

   It is usually necessary to soften wax before its removal. This process
   is referred to as cerumenolysis, and is achieved using a solution known
   as a cerumenolytic agent which is introduced into the ear canal. The
   most common home-remedy for this purpose is olive oil. Other
   commercially available and common cerumenolytics include:
     * [under multiple brand names] Carbamide peroxide (6.5%) and
       glycerine
     * Sodium bicarbonate B.P.C. (sodium bicarbonate and glycerine)
     * Various organic liquids ( glycerol, almond oil, mineral oil, baby
       oil)
     * Cerumol ( arachis oil, turpentine and dichlorobenzene)
     * Cerumenex ( Triethanolamine, polypeptides and oleate-condensate)
     * Exterol, Otex (UK brand name) ( urea, hydrogen peroxide and
       glycerine)
     * Docusate, an active ingredient found in laxatives

   A cerumenolytic should be used 2-3 times daily for 3-5 days prior to
   the cerumen extraction. Although most commercially available
   cerumenolytics available in the U.S. are identical, containing
   carbamide peroxide (6.5%) and glycerine, a 10% solution of sodium
   bicarbonate was found to be a more effective cerumenolytic than several
   commercially-available solutions (Cerumenex, Auralgan) and numerous
   organic liquids, including glycerine, olive oil, and alcohol.
   Additionally, 1 mL of docusate was also found to be a more effective
   cerumenolytic than several commercially-available solutions (Cerumenex,
   Debrox) . Docusate may be extracted from liquid preparations of
   laxatives, such as Colace.

Syringing

   Once the cerumen has been softened, it may be removed from the ear
   canal by irrigation. Ear syringing techniques are described in great
   detail by Wilson & Roeser, and Blake et al., who advise pulling the
   external ear up and back, and aiming the nozzle of the syringe slightly
   upwards and backwards so that the water flows as a cascade along the
   roof of the canal. The irrigation solution flows out of the canal along
   its floor, taking wax and debris with it. The solution used to irrigate
   the ear canal is usually water, normal saline, sodium bicarbonate
   solution, or a solution of water and vinegar to help prevent secondary
   infection.

   Patients generally prefer the irrigation solution to be warmed to body
   temperature, as dizziness is a common side effect of syringing with
   fluids that are colder or warmer than body temperature. Sharp et al.
   recommend 37 °C, while Blake et al. recommend using water at 38 °C, one
   degree above body temperature, and stress that this should be checked
   with a thermometer.

Curette method

   The earwax is removed through the use of an ear pick, which physically
   dislodges the earwax and scoops it out of the ear canal. In the west,
   use of a curette or ear pick is often only done in the hands of health
   professionals and practiced in cases of serious blockage in the ear.
   However curetting earwax using an ear pick is common in East Asia and
   often done at home and also serves as an act to foster a sense of
   intimacy. As the earwax of most East Asians is of the dry type, it is
   extremely easy to remove all earwax via light scraping with an ear
   pick.

Hazards

   A postal survey of British general practitioners found that only 19%
   always performed the procedure themselves – many delegated the task to
   practice nurses, some of whom had received no instruction. This is
   problematic, as while the removal of cerumen is a commonplace
   procedure, it is not without risk. Irrigation can be performed at home
   with proper equipment as long as the person is careful not to irrigate
   too hard. All other methods should only be carried out by individuals
   who have been sufficiently educated and trained in the procedure.

   Bull advised physicians: "After removal of wax, inspect thoroughly to
   make sure none remains. This advice might seem superfluous, but is
   frequently ignored." This was confirmed by Sharp et al., who, in a
   survey of 320 general practitioners, found that only 68% of doctors
   bothered to inspect the canal after the syringing procedure to check
   that the wax was removed. As a result, failure to remove the wax from
   the canal made up approximately 30% of the complications associated
   with the procedure. Other complications included otitis externa, pain,
   vertigo, tinnitus, and perforation of the ear drum. Based on this
   (single) study, a rate of major complications in 1/1000 ears syringed
   was suggested.

   Claims arising from ear syringing mishaps account for about 25% of the
   total claims received by New Zealand's Accident Compensation
   Corporation ENT Medical Misadventure Committee. While high, this is not
   surprising, as ear syringing is an extremely common procedure. Grossan
   suggested that approximately 150,000 ears are irrigated each week in
   the United States, and about 40,000 per week in the United Kingdom.
   Extrapolating from data obtained in Edinburgh, Sharp et al. place this
   figure much higher, estimating that approximately 7000 ears are
   syringed per 100,000 population per annum. In the New Zealand claims
   mentioned above, perforation of the tympanic membrane was by far the
   most common injury resulting in significant disability.

   A syringe should be used to gently stream water into the ear. For
   children the rate and speed should be lower. After irrigating, tip the
   head to allow the water to drain. Irrigation may need to be repeated
   several times. If the water stream hurts then the flow should be
   slower. It is better to irrigate too gently for a long period than
   irrigate too forcefully attempting to remove wax quickly. This
   procedure can be done at home in the shower using a self-use ear
   irrigation syringe with a right angle tip. After the wax is removed,
   the ear can be dried tipping the head then gently pulling the ear
   upwards to straighten the ear canal. If this does not remove enough
   water, the ear can be dried with a hair dryer set on low.

   It is generally advised not to use cotton swabs ( Q-Tips or cotton
   buds) as these will likely push the wax further down the ear canal and,
   if used carelessly, perforate the eardrum. Also, the cotton head may
   fall off becoming lodged in the ear canal. Cotton swabs should be used
   only to clean the external ear.

Alternative practices

Ear candling

   Ear candling, a folk medicine practice, is also used to remove ear wax
   and is claimed to improve ear health. It involves placing a hollow
   candle in the ear canal and lighting it; the rising hot air is believed
   to pull out the toxins and wax. An earwax-like substance does indeed
   collect inside the ear candle as it burns - even if it is only placed
   in a clean, dry drinking glass. Ear candles are a fringe remedy in
   North America and Europe; skeptics argue its claimed benefits are not
   supported by scientific evidence. Ear candles can also drip hot melted
   candle wax inside a person's ear; if the hot wax lands on the eardrum,
   it can cause great pain and possible hearing damage. Seely, Quigley and
   Langman reported that, in a survey of 122 ENT physicians, 21 ear
   injuries were reported due to ear candling . Ernst, in a review of the
   literature, finds that ear candling has no real effect on earwax
   removal, and poses a danger of ear injuries. He concludes that ear
   candling is "a triumph of ignorance over science".

Earwax in whales

   Many species of whale have an annual buildup of earwax, adding one,
   two, or four layers (depending upon the species) each year. Similar to
   the incremental dating method of dendrochronology for trees, the number
   of layers can be counted to determine the age of the whale after its
   death.

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