Itching of the ear is one of the most common complaints of patients. Itch is usually because of common causes like an allergy or infection (e.g., fungus), but some forms of ear itch may occur with inflammation or infection. This review examines the many types and causes of ear itch and the corresponding treatment.
PATHOGENESIS OF EAR ITCH
Itch from the ear canal is transmitted by special nerve fibers called C-fibers. The sensation of the skin of the ear canal follows this approximate general pattern: on the floor and posterior wall, where the innervation is through the auricular branch of the vagus (Arnold nerve); on the roof and anterior wall, where the innervation is through the auriculotemporal nerve arising from the mandibular branch of the trigeminal nerve; and the posterior ear canal, which is innervated by the facial nerve. The auricle also has contributing fibers from the cervical spine. The itch receptors for pruritoceptive itch are nerve endings that contain receptors for H1 and H4 (triggered by histamine), PAR2 (triggered by tryptase, kallikreins, cockroach, dust mites, etc.), IL-31R (for IL-31), LTB4 receptor (for LTB4), NK1 receptor (for substance P), and TRPV1 expression.
There are four types of itch:
- Pruritoceptive itch, which is initiated in the skin from a primary source of inflammation, infection, or growth.
- Neuropathic itch, initiated in the peripheral or central nervous system without cutaneous inflammation. It is defined as a sensation of itch without a pruritogenic stimuli.
- Neurogenic itch, which is initiated in the brain or spinal cord without nerve damage and leads to epidermal cytokine responses.
- Psychogenic itch, initiated in the brain due to psychiatric illness.
Psychogenic pruritus does not interfere with sleep, while most other itchy conditions affect sleep. Clinicians must suspect infestations when more than one family member complains of itch for it can be seen in infants more commonly than adults. If you notice bleeding upon examination of the ear canal, suspect eczema, irritant, or lichen simplex chronicus from a repetitive itch-scratch cycle. Although outer ear itch can develop from any of the above four etiologies, the most common cause of ear itch is pruritoceptive itch.
INFLAMMATORY CAUSE OF EAR ITCH
The initiating factors underlying chronic itching of the external ear canal are mainly inflammatory in nature. The inflammatory causes of ear itch are either external or internal. External causes are more common, like contact dermatitis, irritant dermatitis, infectious dermatitis, or dermatitis from a primary malignancy. Chronic inflammation also happens due to exogenous agents, such as contact allergy to hair care products. Other agents include nickel from tragus piercings and polishes or plastic materials used in hearing aids or ear plugs. For patients who experience ear itching as a reaction to their hearing aid mold, we recommend spreading a thin coat of Vaseline around the hearing aid before placing it into the ear. If itching is occasional, ask the patient to use hydrocortisone 1% ointment around the hearing aid. If the itching is severe, ask the patient to have the mold material changed to something less allergenic.
Infectious agents can induce ear itch, especially among diabetic patients. The moisture in the medial canal due to the use of hearing aids, Bluetooth ear phones, or ear plugs can break down the skin barrier and make the skin more susceptible to irritation. Internal causes of inflammation include skin eruptions, such as seborrheic dermatitis (dandruff), psoriasis, and eczema. For patients with dandruff, flaky skin can be seen through otoscopy. Often, the same flaky rash can be seen between the patient's eyebrows, around the nose, and on the scalp. Psoriasis occurs as silvery plate-like scales that can be seen in the ear canal, on the scalp, face, elbows, and knees.1 Many therapeutic approaches have emerged in the past few years to treat psoriasis in a whole new way.2
TREATMENT FOR PRURITOCEPTIVE ITCH
The first step to treating ear itch is to establish a healthy skin barrier by reducing the skin pH with a diluted vinegar rinse three times daily for 10 days (10:1 sterile water to white vinegar mixture) or a 9:1 isopropyl alcohol (70%) to vinegar mixture. Next, calm the inflammation using an over-the-counter 1% hydrocortisone cream three times daily for one to two weeks. Instruct the patient not to use any cotton-tipped applicator in the ear, and avoid soap and haircare products from going into the ear. We also ask patients to apply a thin coat of mineral oil in the ear canal three times a week.
If the itch is due to allergies, whether local or seasonal, then consider recommending an over-the-counter antihistamine, such as cetirizine 10 mg to be take once daily at night. If these treatments do not help, consider referring the patient to both an otolaryngologist and a dermatologist. Topical fluocinolone in almond oil can also be used for this condition, although we usually recommend mineral oil, which is more affordable. For overly dry ear canals devoid of cerumen, instruct the patient to put one drop of oil once a week in the ear. For significant itching, topical hydrocortisone 1% or triamcinolone 0.1% can be applied as needed. Highly potent steroid ointments (e.g., clobetasol [Temovate], betamethasone-augmented [Diprolene]) should be avoided to keep the ear canal's thin skin from getting even thinner.
New medications that help inflammatory itching are now available or in the pipeline. Topical calcineurin inhibitors like pimecrolimus 1% cream have shown efficacy in treating itching of the external auditory canal.3 The most promising treatment is crisaborole 2% ointment, which blocks phosphohdiesterase type 4 and is FDA-approved for eczema. Next is dupilumab, which is a biologic injection that blocks IL-4 and helps manage itch due to atopic dermatitis. Nemolizumab blocks IL-31 and the itch in cases of severe atopic dermatitis. This drug may be important in addressing recalcitrant ear itch since it treats both inflammatory and non-inflammatory itching by affecting the root mediator of itch.4
INFECTIOUS CAUSE OF EAR ITCH
Individuals that over-clean their ear canals can remove the protective cerumen and hence increase the pH of the canal, which increases the likelihood of fungal and bacterial infections. Diabetics are known to have cerumen of higher pH, which contributes to their susceptibility to otitis externa. However, diabetics are more prone to saprophytic fungi that only grow on the cerumen and do not cause infection, i.e., ear canal skin infection.
In acute fungal otitis externa, which is not due to saprophytic fungi, itching is common. In fact, itching is the primary distinguishing symptom between fungal and bacterial acute otitis externa. The symptoms of itching in otitis externa is mainly due to the body's immune reaction once fungi have compromised the skin barrier. Ear itching in fungal otitis externa is treated by cleaning the canal debris and keratin, followed by acidification using boric acid powder. Applying nystatin-triamcinolone ointment helps give patients immediate relief. This procedure can be repeated every three days until the problem clears up. Using a mixture of alcohol and vinegar, the patient can irrigate the ear canal using a syringe three times a day for two to three days after placing the ointment in the canal. Strict dry ear precautions should be observed for a few weeks after the infection fully resolves.
INFESTATION AND FOREIGN BODY
Foreign bodies, whether they are insects that crawl into the ear canal or objects that are intentionally or unintentionally placed into the ear canal, can cause itchy sensations. A Japanese study showed that older adults were more likely than children to get a foreign body in the ear canal, especially during summer months.5 However, others have found that children 10 years and younger make up the majority of cases involving foreign bodies in the ear.6 Rare infestation with mites have been reported, although it might accompany symptoms of otalgia and otorrhea.7 Cevik, et al., showed that Demodex mite was found in 5.8 percent of cases of persistent itchy ear canals, while the normal control tested positive in two percent of individuals.8 Some patients develop itching in the ear canal due to hairs in the ear canal with ends on the tympanic membrane, causing itching sensations and irritation of the tympanic membrane. Some patients may experience hearing rubbing sounds as well. In-clinic removal or at-home irrigation with an alcohol and vinegar mixture (as previously mentioned) will help relieve the itchy sensation.
GROWTH CAUSE OF ITCH
Although growths mostly cause pain in the ear canal, some can present with itching. Bala, et al., described a 42-year-old woman with ear itch and pain in the ear canal that turned out to be an external auditory canal cholesteatoma.9 Seborrheic keratosis is a warty-like growth that can present in the ear canal with itching. Treatment requires removal of the growth.10 A recent case report on apocrine hidrocystoma of the external auditory canal noted that the mass presented with itching. After the third recurrence, nystatin triamcinolone ointment helped reduce the size of the mass and severity of the itching sensation.11
ITCHY EAR SYNDROME
Itchy ear syndrome was described by Shenoy, et al., in a group of patients with chronic external auditory canal itch but without any inflammation upon biopsy.12 This group of non-inflammatory chronic itch most likely represents a non-pruritoceptive etiology. The patients most likely had a neuropathic or psychogenic itch. Yilmaz, et al., conducted a case-controlled study involving 100 patients with isolated external auditory canal itch, and found that 43 percent of the participants had type D personalities, i.e., have anxiety and/or depression. Notably, only 15 percent of the controls met the criteria for a type D personality.13 Therefore, in assessing a patient with external auditory itching, the individual's anxiety levels should also be taken into consideration. In such cases, without proper anxiolysis, the itch will not be topically controllable.
It is also important to visualize the tympanic membrane. If it is intact, this 10-day course is recommended: Flush the ear canal using a baby nasal syringe pointed upwards in the ear canal and a solution of 9:1 of 70% isopropyl alcohol and vinegar, performed three times daily. This will lower the pH of the epidermis and reestablish a healthy barrier. However, if the tympanic membrane is compromised, clotrimazole solution, which is safe for the middle ear, should be used three times daily. For an in-clinic option, the physician can use a compound of boric acid powder and fill the canal with nystatin/triamcinolone cream to reduce the itch. This also allows for in-clinic suction after a few days.
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