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|Classification and external resources|
Wet-type human earwax
|Classification and external resources|
Wet-type human earwax
Earwax, also known by the medical term cerumen, is a yellowish waxy substance secreted in the ear canal of humans and other mammals. It protects the skin of the human ear canal, assists in cleaning and lubrication, and also provides some protection from bacteria, fungi, insects and water. Excess or impacted cerumen can press against the eardrum and/or occlude (block) the external auditory canal or hearing aids, potentially hindering hearing.
Excessive earwax may impede the passage of sound in the ear canal, causing conductive hearing loss. Hearing aids may be associated with increased earwax impaction. It is also estimated to be the cause of 60–80% of hearing aid faults.
Cerumen is produced in the outer third of the cartilaginous portion of the 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 shed layers of skin, with 60% of the earwax consisting of keratin, 12–20% saturated and unsaturated long-chain fatty acids, alcohols, squalene and 6–9% cholesterol.
There are two distinct genetically determined types of earwax: the wet type, which is dominant, and the dry type, which is recessive. While Asians and Native Americans are more likely to have the dry type of cerumen (gray and flaky), African and European people 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. In Japan, wet-type earwax is more prevalent among the Ainu, in contrast to that country's Yamato majority. The consistency of wet type earwax is due to the higher concentration of lipid and pigment granules (50% lipid) in the substance than the dry type (30% lipid).[verification needed]
A specific gene has been identified that determines whether people have wet or dry earwax. The difference in cerumen type has been tracked to a single base change (a single nucleotide polymorphism) in a gene known as "ATP-binding cassette C11 gene". Dry-type individuals are homozygous for adenine whereas wet-type requires at least one guanine. Wet-type earwax is associated with armpit odor, which is increased by sweat production. The researchers conjecture that the reduction in sweat or body odor was beneficial to the ancestors of East Asians and Native Americans who are thought to have lived in cold climates.
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 comparable to that of fingernail growth) to the walls of the ear canal, and move 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 expulsion.
Lubrication prevents desiccation, itching, and burning 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.
While studies conducted up until the 1960s found little evidence supporting antibacterial activity for cerumen, more recent studies have found that cerumen has a bactericidal effect on some strains of bacteria. Cerumen has been found to reduce the viability of a wide range of bacteria, including Haemophilus influenzae, Staphylococcus aureus, and many variants of Escherichia coli, sometimes by as much as 99%. 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 slight acidity of cerumen (pH typically around 6.1 in normal individuals).
Movement of the jaw helps the ears' natural cleaning process. The American Academy of Otolaryngology discourages earwax removal unless excess earwax is causing health problems. While a number of methods of earwax removal are effective, their benefits as compared to each other is not yet determined. A number of softeners are effective; however, if this is not sufficient, the most common method of cerumen removal is syringing with warm water. A curette method is more likely to be used by otolaryngologists when the ear canal is partially occluded and the material is not adhering to the skin of the ear canal. Cotton swabs, on the other hand, push most of the earwax farther into the ear canal and remove only a small portion of the top layer of wax that happens to adhere to the fibres of the swab.
This process is referred to as cerumenolysis. A review of studies found that topical preparations for the removal of earwax may be better than no treatment, and there may not be much difference between types, including water and olive oil. However, there were not enough studies to draw firm conclusions, and the evidence on irrigation and manual removal is equivocal.
Commercially or commonly available cerumenolytics include:
A cerumenolytic should be used 2–3 times daily for 3–5 days prior to the cerumen extraction.
Once the cerumen has been softened, it may be removed from the ear canal by irrigation, but the evidence on this practice is equivocal. This may be effectively accomplished with a spray type ear washer, commonly used in the medical setting or at home, or with a bulb syringe at home. 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 warm 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 ear washing or 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. Any other temperature may cause vertigo, just as used when testing the caloric reflex test.
A syringe or spray type ear washer should be used to gently stream water into the ear. For children the rate and speed should be lower. After irrigating, the head is tipped 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 an ear irrigation syringe with a right angle tip. After the wax is removed, the ear can be dried by tipping the head and gently pulling the ear upwards to straighten the ear canal.
Earwax can be removed with an ear pick/curette, which physically dislodges the earwax and scoops it out of the ear canal. In the west, use of ear picks is usually only done by health professionals; a modified curette having a safety stop to prevent deep insertion for self-use is available. Curetting earwax using an ear pick was common in ancient Europe and still practiced in East Asia. Since the earwax of most Asians is of the dry type, it is extremely easily removed by light scraping with an ear pick, as it simply falls out in large pieces or dry flakes.
It is generally advised not to use cotton swabs (Q-Tips or cotton buds), as doing so will likely push the wax farther down the ear canal, and if used carelessly, perforate the eardrum. Abrasion of the ear canal, particularly after water has entered from swimming or bathing, can lead to ear infection. Also, the cotton head may fall off and become lodged in the ear canal. Cotton swabs should be used only to clean the external ear.
Ear candling, also called ear coning or thermal-auricular therapy, is an alternative medicine practice claimed to improve general health and well-being by lighting one end of a hollow candle and placing the other end in the ear canal. According to medical researchers, it is both dangerous and ineffective. Advocates say that the dark residue that shows after the procedure is extracted earwax, proving the efficacy of the procedure. Studies have shown that in fact the same residue is left whether or not the candle (which is made of cotton fabric and beeswax and leaves a residue after burning) is inserted into an ear. This means that the wax residue is derived from the candle itself and not the ear. The color of the candle wax deliberately matches the light brown-colored wax of the human ear, making the distinction between the two more difficult for a layperson. Because the candle itself is a hollow tube, some of the hot burnt wax can drop down inside the candle, into the ear canal, potentially rupturing the eardrum. The American Academy of Otolaryngology states that ear candles are not a safe option for removing ear wax, and that no controlled studies or scientific evidence support their use for ear wax removal. The Food and Drug Administration has successfully taken several regulatory actions against the sale and distribution of ear candles since 1996, including seizing ear candle products and ordering injunctions.
Home "ear vacs" were ineffective at removing ear-wax, especially when compared to a Jobson-Horne probe.
A postal survey of British general practitioners found that only 19% always performed cerumen removal themselves. It is problematic as the removal of cerumen is not without risk, and physicians and nurses often have inadequate training for removal. 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 trained in the procedure.
The author 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 inspected the ear canal after syringing 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 (swimmer's ear), which involves inflammation or bacterial infection of the external acoustic meatus, as well as pain, vertigo, tinnitus, and perforation of the ear drum. Based on this 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.
When a man is becoming dull of hearing, which happens most often after prolonged headaches, in the first place, the ear itself should be inspected: for there will be found either a crust such as comes upon the surface of ulcerations, or concretions of wax. If a crust, hot oil is poured in, or verdigris mixed with honey or leek juice or a little soda in honey wine. And when the crust has been separated from the ulceration, the ear is irrigated with tepid water, to make it easier for the crusts now disengaged to be withdrawn by the ear scoop. If it be wax, and if it be soft, it can be extracted in the same way by the ear scoop; but if hard, vinegar containing a little soda is introduced; and when the wax has softened, the ear is washed out and cleared as above. ... Further, the ear should be syringed with castoreum mixed with vinegar and laurel oil and the juice of young radish rind, or with cucumber juice, mixed with crushed rose leaves. The dropping in of the juice of unripe grapes mixed with rose oil is also fairly efficacious against deafness.
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