Ear Anomalies: Types, Causes, and Correction

• Auricular defects can lead to psychosocial issues, potentially improved by surgical correction.
• Congenital external ear abnormalities are prevalent, displaying different presentations, from total absence to minor irregularities.
• External ear anomalies are classified by cause, stemming from mechanical events affecting fetal growth or developmental errors.
• Deformations/disruptions retain tissue components, while malformations have components that are absent.
• Anomalies include size, position, anatomical components variations and named conditions like cryptotia and Stahl's ear.
• Acquired defects presentations vary, typically from trauma, burns, or tumor removal.
• Correction aims to create an aesthetically pleasing ear by restoring features, structure, position, and proportion.
• Ear reconstruction is complex due to its framework and soft-tissue envelope resulting in various reconstructive methods for defects like microtia.
• Auricular reconstruction developed through experience and technique appreciation to create a lasting, pleasing ear.
• Advancements are ongoing as surgeons innovate and improve current techniques.
• The chapter is divided into sections covering epidemiology, anatomy, embryology, history, congenital deformities, microtia reconstruction, and acquired deformities.
• Prominent ear reconstruction is discussed elsewhere.

History of microtia and ear reconstruction

• Sushruta, often regarded as the pioneer in the field of plastic surgery, made significant contributions to medical literature, particularly with his detailed descriptions of surgical techniques. His work, particularly regarding ear lobe reconstruction using local flaps, illustrates early understanding of tissue manipulation and the importance of functional and aesthetic restoration in surgical practices dating back to 600 BCE.
• Aelius Galen reconstructed traumatic ear defects for gladiators in the second and third centuries CE.
• Gaspare Tagliocozzi restored defective ears in the sixteenth century.
• Johan Friedrich Diefenbach developed reconstruction techniques for the middle third of the ear and corrected prominent ears centuries.
• Harold Gilles pioneered face reconstructive methods, forming the base for ear reconstructive surgeons.
• Radford Tanzer popularized autologous reconstruction utilizing costochondral cartilage.
• Tanzer's multistage involved usable remnant tissue repositioning/attention paid to the lobule, and cartilage framework contouring from ribs.
• The third stage consisted of construct elevation/superior, posterior and conchal wall construction divided into three sub-stages.
• Burt Brent advanced microtia reconstruction using autologous cartilage in four stages.
• Satoru Nagata refined Tanzer and Brent's method into a two-stage process, paying attention to the incision pattern/coverage over the tragus.
• Françoise Firmin transitioned from Brent's technique which included a classification system for incisions, frameworks, and elevation.
• Fisher and Kasrai, trained with Nagata, modified his technique, reducing reconstruction to a single stage.
• Autologous reconstruction is standard in microtia repair.
• Alloplastic options were trialed to eliminate donor sites and perform earlier interventions.
• Cronin was the first to use silicone in 1966.
• Cronin and Ascough noted TPF was necessary to reduce extrusion in 1978.
• Porous polyethylene is the most successful alloplastic material; it was first used in 1983 with a TPF flap.
• Reinisch reduced extrusion rates down to 7% by refining the technique.

Epidemiology

• Microtia/anotia, which refers to the underdevelopment or absence of the outer ear, has a reported birth prevalence that falls within a wide range, estimated to be between 1 in 3000 and 1 in 20,000. This variation can be attributed to different regional demographics and genetic backgrounds, emphasizing the need for regional studies to understand the specific prevalence in different populations.
• The condition occurs significantly more in males than females, with studies indicating an incidence increase of 20-40% in males. The male-to-female ratio can vary, with some studies establishing an average of 2:1, highlighting a potential genetic or environmental factor that predisposes male fetuses to develop this condition.
• Statistically, a substantial majority of microtia cases are unilateral, meaning they affect only one ear, with rates ranging from 77% to 93%. Furthermore, these unilateral cases are more frequently seen on the right side, occurring in approximately 60% of cases. This lateral preference raises questions about possible prenatal influences that might contribute to this asymmetry.
• In association with other congenital syndromes, microtia is found in 20-60% of affected individuals. The likelihood of bilateral microtia is notably higher when there are additional anatomical abnormalities, suggesting a complex interplay of genetic factors that may affect ear development and associated structures.
• Among patients with craniofacial microsomia (CFM), an estimated 65% also present with microtia. Similarly, 60-80% of individuals diagnosed with Treacher Collins syndrome (TCS), which is characterized by facial bone and soft tissue malformations, are affected by microtia as well, indicating a strong association between these syndromes and ear anomalies.
• The presence of external ear malformations typically signifies the need for comprehensive evaluations of middle and inner ear structures, as these can have implications for hearing and overall auditory function. Health professionals often recommend thorough examinations to ascertain the extent of ear development and any potential complications.
• Aural atresia, defined as the absence or closure of the ear canal, is one of the most common conditions associated with microtia. This condition can adversely affect auditory capacity and is critical for health professionals to consider during diagnosis and treatment.
• Research indicates that about 23% of individuals presenting with aural atresia and microtia might exhibit further complications such as inner ear abnormalities, which can significantly impact one's hearing abilities and necessitate early intervention.
• The prevalence of cryptotia, a lesser-known ear condition characterized by a partially buried auricle, has been reported to be as high as 1 in 400, suggesting that this condition might be more common than previously understood.
• The prevalence of Stahl's ear, often characterized by a pointed or "elfin" appearance due to abnormal cartilage formation, is still largely unknown; however, it has been reported to occur at rates as high as 8% in certain populations in Japan, emphasizing the need for broader epidemiological studies.
• A constricted ear, also known as "microtia type 4," has an estimated prevalence ranging from 1 in 1000 to 1 in 2000. This condition can create various functional issues, further emphasizing the importance of awareness and early clinical intervention.

Embryology

• Ear development starts with the otic placode at 3 weeks gestation including/the external canal at 4 weeks.
• Six ectodermal thickenings known as auricular hillocks develop, beginning at 5 weeks of gestation.
• Hillocks 1-3 are derived from the first branchial arch, and hillocks 4-6 from the second.
• There is controversy regarding correlations with the exact embryologic-anatomic regions.
• The auricle moves from an antero-caudal to postero-cranial position during development.
• The hillocks fuse together to form the auricle.

Growth

• Ear growth trajectory is important for determining the timing of reconstruction.
• Ear length/width reach near adult size by 5 years, width reaching adult size earlier than length.
• Ear width reaches maturation at 6/7 years in females/males respectively.
• Length reaches maturation at 12/13 years in females/males respectively.

Anatomy

• The text covers external anatomy, anthropometrics, cartilage, vasculature, musculature, ligaments, and innervation.

External Anatomy

• The auricle is composed of parts like the helix, scapha, concha, tragus, and lobule.
• The helix begins at the helical root separating the cymba and cavum and merges the lobule.
• The antihelix parallels the helix, separated by the scapha with the lower third projecting as the antitragus forming the triangular fossa.
• The meatus of the external ear canal opens into the cavum concha, hidden anterolaterally by the tragus.
• The lobule lacks cartilage and attachment with the cheek varies.
• The space between the auricle and head is the retroauricular sulcus.

Anthropometrics

• Adult ear height ranges from 5.5–7.5cm and width from 3-4.5cm, with an axis of 20-30° from the vertical.
• The width is 50-60% of height.
• The anterior extends 6.5-7.5cm posterior to the lateral orbital rim, the superior border protruding 1.5-2cm laterally.
• The lower border is at the level of the columella.
• Posterolateral ear projection at the helical root is 21-25° and the conchoscaphal angle is typically around 90°.
• The Frankfort plane is when the infraorbital rim and porion happen.
• The distance from the most anterior aspect of the helix to the lateral eyebrow approximates the height of the ear.

Cartilage

• The framework is made up of the cartilage framework of the normal adult.
• The lobule consists of skin and subcutaneous tissue, unlike other regions of the ear.
• Elastic, fibrocartilage, and hyaline are types of cartilage.
• The elastic cartilage has material properties different than rib hyaline cartilage.
• Alloplastic materials have differing material properties to ear cartilage.

Vasculature

• The blood supply is the posterior auricular and superficial temporal arteries.
• The PAA is the main source vessel to the ear.
• The STA commonly has superior, middle, and inferior anterior auricular branches.
• The PAA emerges posteriorly with branches to the concha, antitragus, and antihelix.
• The STA and PAA anastomose over the helical rim.

Musculature/ligaments/skin

• The auricle has extrinsic (anchor ear to the place) and intrinsic (support framework of the ear) muscular systems.
• The extrinsic includes anterior, superior, and posterior auricularis muscles.
• The intrinsic Includes the major helical, minor helical, tragal and antitragal muscles anteriorly and the auricular oblique and transverse muscles posteriorly.

Innervation

• The auricle is supplied by cranial (auriculotemporal nerve and vagus nerve) and spinal (great auricular and lesser occipital nerves) nerves.
• Important to know the auricular muscle innervation, in order to prevent injury to facial nerve trunks.
• Facial nerve is 6.9mm away from the "pointer" on tragus and is usually medial, inferior, and anterior to the pointer

Etiology

• Environmental and genetic factors play a role in microtia development. The risk factors: maternal illness, maternal diabetes, low birthweight, maternal parity, multiple births, advanced maternal age, Hispanic ethnicity, and high altitude.
• Medications like retinoids are also risk factors for Microtia, thalidomide, and mycophenolate.
• Neural crest cell disruption is a leading cause and genetic factors have been linked.

Congenital ear anomalies excluding microtia

• Contour irregularities can be classified as separate from microtia and proportions or abnormalities can occur.
• Cryptotia, constricted, and Stahl's ear are discuss here. Otoplasty is discussed elsewhere.

Ear molding

• Used to correct deformational anomalies if the appearance can be corrected by gentle manipulation.
• Molding most effective when initiated in the first 6 weeks of age.
• Treatment length should be estimated on age at presentation equation.

Cryptotia

• The absence of the superior portion of the auriculo-temporal sulcus, along with an upper pole that is interred in the skin in the location.
• Can lead to difficulty with eyewear.
• Early treatment of cryptotia is nonsurgical; it include distracting and pulling the ear to use splints and tape.
• Moderate to severe cryptotia requires recreation of the superior sulcus with grafts or local skin flaps.

Stahl's ear

• Characterized by a third crus accessory and flattening or deformity.
• Opportunity for treatment best with ear molding early due to better outcomes.
• Surgical methods can be divided into: cartilage-sparing or cutting techniques.

Constricted ear

• Tanzer classifies as an impression that the helical rim is tightened by a purse string with 3 groups defining treatment.
• Chul Park's algorithm classification involves amount of cupping/lidding as well as cartilage strength, and amount shortage.