Conditions of the external ear

Congenital anomalies

Congenital anomalies can range from total absence of the ear through to mild cosmetic deformities such as tiny accessory auricles or skin tags. External ear anomalies can be isolated or may be associated with middle ear deformity. The external and middle ear originate from the first and second branchial arches, whereas the cochlea is of neuroectodermal origin. This means that an individual may have no pinna or ear canal but a normal cochlea may well be present. In these circumstances, sound can be transmitted from a hearing aid connected to an osteo integrated peg that is screwed into the mastoid bone. (Tab 40.1)

Children who have a significant deformity of the pinna (microtia) can be helped with osteointegrated implants to which a prosthetic ear is connected (Fig. 40.3). The ear can be unclipped prior to playing violent sport (e.g. rugby) and this unsettles the opposition. Preauricular sinuses are a common congenital abnormality and occasionally need excising because of recurrent infections and discharge. The sinus usually ends near the external canal but occasionally the track is very extensive and is closely related to the facial nerve, which makes life exciting.

Prominent ears are a common deformity which usually results from the absence of the antihelix curve. Various car­tilage scoring methods are available to correct this deformity.

Trauma

Trauma often affects the external ear. A haematoma of the pinna occurs when blood collects between the pen­chondrium and the cartilage. The cartilage receives its blood supply from the perichondrial layer and will die if the haematoma is not evacuated (cauliflower ear). An extensive excision, under general anaesthetic, with a pressure dressing and antibiotic cover is recommended (see Fig. 40.4).

Foreign bodies in the ear canal need to be treated with the greatest respect. If an object is not simply removed at the first attempt, it is better to do it with the aid of a microscope and general anaesthesia. An active 2-year-old with a bead in the ear can be a formidable opponent (Fig. 40.5).

Inflammatory disorders

Inflammatory disorders of the external ear are extremely common. Otitis externa frequently presents to general prac­tice and to ear, nose and throat (ENT) surgeons. There is generalised inflammation of the skin of the external auditory meatus. It can occur as an acute episode or can run a more chronic course. The cause is often multifactorial but includes general skin disorders, such as psoriasis and eczema, and trauma. Common pathogens are pseudomonas and staphylococcus bacteria, and amongst fungi, candida and aspergillus. Once the skin of the ear canal becomes soggy and oedematous, skin migration stops and debris collects in the ear canal which acts as a substrate for the pathogens. The hallmark of acute otitis externa is severe pain (evidently on a par with childbirth). Unlike otitis media, movement of the pinna elicits pain. The condition is often bilateral.

The initial treatment is with topical antibiotics and steroid ear drops, together with analgesia. If this fails meticulous removal of the debris with the aid of an operating micro­scope is required. Regular cleaning of the canal, together with topical steroids, needs to be continued until normal skin migration resumes. If fungal infection is present it can easily be recognised by the presence of hyphae and spores within the canal (Fig. 40.6). Fungal infection causes irritation and itch, and the treatment is meticulous removal of the fungus and any debris, as well as stopping any concurrent antibiotics.

Systemic antibiotics are rarely required for otitis externa but should be used if cellulitis of the pinna occurs (Fig. 40.7).

Necrotising otitis externa is a rare but very important con­dition. It presents as a severe, persistent, unilateral otitis externa in an immunocompromised individual, for example it is important to think of the diagnosis in an elderly diabetic. Osteomyelitis of the skull base occurs and usually the infect­ing organism is Pseudomonas aeruginosa. Several cranial nerves (VII, IX and X) may be destroyed by the progressing infection. Intensive systemic antibiotic treatment is required and the disease process is monitored by high-resolution imaging.

A furuncle of the external ear is an infection of a hair follicle and is due to a staphylococcal infection. Moving the pinna causes extreme pain. Local treatment of the ear canal (oto-wick and steroid drops) together with systemic antibiotic therapy is required.

Neoplasms

  Benign neoplasms

Benign neoplasms of the external ear are common if osteomas are included. These arise from the bone of the ear canal in individuals who have done a lot of swimming in cold water. No treatment is required unless they obstruct the migration of skin out of the canal. Other benign tumours include papillomas and adenomas.

Malignant primary tumours

Malignant primary tumours of the external ear are either basal cell or squamous cell carcinomas (Fig. 40.8). Both may present as ulcerating or crusting lesions which grow slowly and may be ignored by elderly patients. Squamous cell carci­nomas may metastasise to the parotid and/or neck nodes and need radical surgical clearance. The ear canal may be invaded by tumours from the parotid and postnasal space carcinoma which ‘creep’ up the eustachian tube. All resectable malig­nant tumours of the ear are treated primarily with surgery with or without the addition of radiation therapy.

The external ear

  Otitis externa responds to topical medication

   Unilateral otitis externa in a diabetic may be fatal

Auricular haematoma needs a robust incision, drainage and pressure dressing

Think osteo integration for congenital malformations