What is external auditory canal? All about its structure, disorders, and infections

Structure and function
The passageway in the ear that leads from the outer ear to the eardrum is known as the external auditory canal or the external auditory meatus. It acts as a pathway for sound waves to travel from the outer ear to the eardrum. It aids in protecting the middle and inner ear structures (Images: Canva)

Congenital disorders
Congenital disorders like the absence of closure (atresia) of the external canal, which occurs due to the failure of canalization of the ectodermal core. A fistula may also be formed, known as the collaural fistula. Such a fistula may have two openings, one present in the neck and the other in the external canal.

Impacted wax
Impacted wax is made up of secretions of the sebaceous glands, hair, and keratin, along with dirt and secretions by specialised glands in the external auditory canal. Wax usually has a protective function, but it may get impacted against the eardrum. Syringing may help in dealing with this.

Minor lacerations
Minor lacerations may be seen in the skin of the external auditory canal, which often result from injury by Q-tips, hair pins, needles, or even matchsticks. An unskilled instrumentation by the healthcare provider may also cause injury.

Furuncle (localised acute otitis externa)
A furuncle refers to an infection of the hair follicle. The affected person may experience severe pain and tenderness, out of proportion to the size of the furuncle. There may be pain in the ear while chewing, and lymph nodes may be enlarged in the neck.

Diffuse otitis externa
A diffuse inflammation of the meatal skin is known as diffuse otitis externa. It may also spread and involve the pinna of the ear. It is common in hot and humid areas, and often seen in people who swim. Excessive sweating may change the pH of the skin, which favours the growth of pathogens.

Otomycosis
Otomycosis is a fungal infection of the ear canal that occurs due to fungi like Aspergillus niger, A. fumigatus, or Candida albicans. The person may experience intense itching, discomfort, or pain in the ear. The debris may be removed by syringing, suction, or mopping.

Malignant otitis externa
Malignant otitis externa, also known as necrotising otitis externa, shows an inflammation of the external auditory canal caused by an infection with Pseudomonas. This is often seen in elderly people with diabetes or those taking immunosuppressive drugs.

Eczematous otitis externa
Eczematous otitis externa often results from hypersensitivity to infective organisms. Even topical ear drops containing chloramphenicol or neomycin may trigger this condition. It results in intense irritation, vesicle formation, oozing, and crusting.

Neurodermatitis
Neurodermatitis is caused by compulsive scratching of the external auditory canal due to psychological factors. Intense itching is a major complaint, and the raw area left by scratching may get infected. An ear pack and bandages may help prevent scratching. (Disclaimer: This article, including health and fitness advice, only provides generic information. Don’t treat it as a substitute for qualified medical opinion. Always consult a specialist for specific health diagnosis)