Applied Clinical Anatomy and Development

The external ear includes the auricle and auditory canal ( ▶ Fig. 6.1 a). The anterior and posterior surfaces of the auricle are characterized by a typical relief ( ▶ Fig. 6.1 a, b) with a long axis of 62 to 64 mm (in the adult) and an inclination of 15 to 25 degrees. The distance between the anterior helical rim and the mastoid is less than 20 mm ( ▶ Fig. 6.23c). The auricle consists of elastic cartilage (1.0–3.0 mm), enveloped within thick skin and firmly attached to the perichondrium, apart from the lobule which is free of cartilage. The posterior surface has an additional layer of fat between the skin and perichondrium. The auricle develops from the mesenchymal hillocks 1, 2, and 3, arising from the first “branchial arch” and the mesenchymal hillocks 4, 5, and 6 of the second “branchial arch.” The auditory canal develops from the first branchial cleft ( ▶ Fig. 6.2). ¹

The auricle migrates from an anterocaudal position to a posterocranial position.

The auricle reaches 85% of its final length by the age of 6 years.

6.3 Acquired Disorders of the External Ear

6.3.1 Furuncle (Otitis Externa Circumscripta)

This is typically caused by a Staphylococcal infection of the hair follicle in the skin of the cartilaginous ear canal.

Diagnosis is made by finding a discrete red swelling of the ear canal with ear pain and tenderness, made worse by gently pulling or pressing the pinna or tragus.

Treatment is with antibiotic and steroid dressings changed daily. Incision and drainage under general anesthesia may be necessary, and in recurrent cases, it is wise to check the child for diabetes mellitus or immune dysfunction.

6.3.2 Swimmer’s Ear (Otitis Externa Diffusa)

This may be caused by traumatization of macerated skin of the ear canal. Other factors include infection of cerumen after cleaning, use of hearing aids, and contamination of the ear canal with materials from water. Bacterial and/or fungal infection may supervene with Pseudomonas aeruginosa (54%), Staphylococcus epidermidis (9.1%), S. aureus (1.0%), Proteus, Candida species, or Aspergillus. The skin is red, edematous, and desquamated. The child may complain of itching, pain, and discharge. He/she may be mildly hearing impaired due to accumulated debris in the ear canal and, in severe cases, may be febrile and unwell. (See ▶ Fig. 6.3.)

Treatment is by meticulous cleaning of the ear (not always easy or possible in a child), adequate analgesia, and topical antimicrobial therapy, ideally with a local steroid, for up to a maximum of 2 weeks to avoid sensitization or mycosis. We recommend ciprofloxacin 0.3% and dexamethasone 0.1% as sterile otic suspension. A soft cotton or small pressed sponge, self-expanding ² and soaked with antibiotic–steroid solution (based on culture results: Methicillin-resistant S. aureus 60%, clindamycin 33% resistance rate, increased resistance after long-time therapy), may be useful, with antimycotic therapy if necessary. ³

6.3.3 Eczematous Otitis

This occurs with atopic eczema, seborrheic dermatitis, psoriasis, neurodermatitis, and purulent or chronic otitis externa (dermatological diagnoses) ( ▶ Fig. 6.4). Treatment is directed at the dermatological condition, with attention to aural toilet as needed. In susceptible children, it is important to avoid sprays and irritant shampoos.

6.3.4 Bullous Myringitis (Otitis Externa Bullosa Hemorrhagica)

This is caused by a viral infection (e.g., influenza). Pain is often severe.

Hemorrhagic bullae involve the tympanic membrane, skin, and medial canal, so the effects of otitis media and otitis externa are combined. The child may have a conductive deafness. Treatment is expectant with attention to pain control and draining the blebs.

6.3.5 Erysipelas (Auricular Cellulitis)

This is an acute infection with streptococcus in the ear region ( ▶ Fig. 6.5). It is characterized by a raised intensely red edematous eruption of the skin. The child complains of pain, high temperature, and increasingly bad general condition as the infection spreads into the skin of the face. It is distinguished from dermatitis as the child with erysipelas is usually systemically unwell, and from perichondritis, where the lobule is free of infection. Treatment is with antibiotics (penicillin), modified as needed by culture and sensitivity result, and analgesics.

6.3.6 Chronic External Otitis

This is characterized by debris and pus but seldom occurs in children. ⁴ There may be granulations on the tympanic membrane or the skin of the ear canal. Treatment is as for otitis externa diffusa, with management of acute exacerbations as they occur.

Chronic fungal infection may need antimycotic agents.

6.3.7 Perichondritis

This is covered later in the chapter (see section on Complications of Surgery to the Pinna; see also ▶ Table 6.3) See ▶ Fig. 6.6.

6.4 Trauma

The exposed position of the auricle predisposes it to a large number of different injuries. The cartilage is dependent upon nutrition from its surrounding tissues (a “bradytrophic” structure), so shearing forces can cause devascularization and necrosis.

6.4.1 Penetrating Trauma

Some piercings even in the region of the helix cause inflammation associated with granulation tissue ( ▶ Fig. 6.7). This can lead to loss of the auricle by perichondritis.

6.4.2 Chemical Burns

Acid burns result in superficial coagulation necrosis, whereas alkali produces deeper more penetrating injuries.

The ear should be immediately cleaned with clear water with application of sterile, cool compresses, and steroid ointments. Later treatment may involve surgical removal of necrotic tissue and reconstruction at a later stage. ^{5,​ 6}

6.4.3 Thermal Injuries (Burns)

These are frequently caused by hot liquids (scalding) but are sometimes due to exposure to flames, for example, gas explosions or firework injuries.

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  First-degree burns are caused by short exposure giving rise to painful erythema, tissue swelling, and superficial defects. Management is by cooling, local ointments, and analgesia. Complete recovery is usually observed within a few days.

  
  
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  Second-degree (partial-thickness) burns involve the superficial layer of skin and the dermis. Therapy is as for first-degree burns, with spontaneous healing expected within 14 days.

  
  
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  Third-degree (full-thickness) burns are caused by open fire or electrical burns, lead to tissue destruction and necrosis (even cartilage), and may be complicated by extensive tissue infection and deformity, requiring later reconstructive surgery. ⁶ Therefore, we need cartilage protection by a cooling sterile dressing. These children benefit from interdisciplinary cooperation (e.g., management on a burns unit) and tetanus prophylaxis.

6.4.4 Otohematoma and Otoseroma

Hematomas or seromas ( ▶ Fig. 6.8) develop between the cartilage and the nutrient skin–perichondrium layer. They are caused by tangential shearing movement due to blunt trauma, typically during sports without protective headgear. Approximately 80% of them are found on the superior aspect of the auricle.

Treatment involves drainage to remove the fluid, with secure apposition of the skin–perichondrium flap, otherwise the fluid will refill. This can be brought about by an anterior incision in the antihelical or conchal fold ( ▶ Fig. 6.8), with removal of clotted blood and granulation tissue, and mild compression with mattress sutures for 1 week.

6.4.5 Partial and Total Avulsion

Road traffic accidents are the cause in more than 40% of cases, and domestic accidents are the cause in over 30%. Although there will inevitably be overlaps when attempting to classify the defects, we still regard classification as worthwhile for didactic reasons ( ▶ Fig. 6.9, ▶ Table 6.1).

Partial defects and partial and total loss will be reconstructed with different methods in a one- or multistage technique, with cartilage of the contra-lateral auricle or rib cartilage. With modern surgical techniques, we are able to get satisfying results ( ▶ Fig. 6.10, ▶ Fig. 6.11). ⁵

Reimplantation of the auricle as a composite graft only takes when small parts are amputated. Larger parts will become necrotic and must be reconstructed with cartilage and skin of the surrounding area ( ▶ Fig. 6.10). ⁵

6.5 Congenital Disorders of the External Ear

Approximately half of the malformations in the head and neck are in the region of the ear. Brent ⁷ reports one auricular malformation in approximately 6,000 neonates. Abnormalities may be isolated or may be part of an inherited syndrome such as Franceschetti’s or Goldenhar’s syndrome. Exogenous factors are presumed to be the cause of the malformation in approximately 10% cases. These include maternal toxins such as thalidomide, alcohol, maternal rubella, and other viral infections. ⁸

6.5.1 Auricular Appendages

These are thought to be due to excess of the mandibular arch (first branchial or pharyngeal arch) formations along the edge of the first branchial (pharyngeal) cleft ( ▶ Fig. 6.12). ^{9,​ 10} They include minor skin tags and accessory auricles. In the presence of normally developed ears, appendages are best excised in the relaxed skin tension lines.

6.5.2 Fistulas and Sinuses

Congenital auricular fistulas, preauricular fistulas, and sinuses are formed by entrapped remnants of epithelium found in similar locations to those described for auricular appendages ( ▶ Fig. 6.12, ▶ Fig. 6.13, ▶ Fig. 6.14). If they have no tendency to recurrent inflammation, they may not require treatment. They may, especially if the orifice is below the tragus, be intimately associated with the facial nerve and surgery can be very challenging (see ▶ 12). ¹¹

6.5.3 Auricular Dysplasias

Classification of auricular dysplasias is shown in ▶ Table 6.2 and ▶ Fig. 6.15.

Arrested development or failures of differentiation of parts of the auricular primordium or the pharyngeal cleft can result in various types of malformation of the external ear ( ▶ Fig. 6.2 and ▶ Fig. 6.15). The most severe manifestation is anotia or complete absence of the external ear (grade III microtia). Lower grade microtia represents a less severe deformity where some of the components of the ear are present, but they are rudimentary and often greatly malformed. The different types of auricular malformations are related to embryological maldevelopment in the region of the mesenchymal hillocks 1 to 6 ( ▶ Fig. 6.2). ¹² Malformations represent an aesthetic impairment that can produce “a significant psychosocial burden during the development of the personality.” ¹³

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