A preauricular sinus is a congenital malformation that manifests as an external small opening in the preauricular region. It has been variably termed preauricular pit, preauricular fistula, preauricular tract, and preauricular cyst.

Preauricular sinuses have an estimated incidence of 0.1–0.9 % in the United States, 0.47 % in Hungary, 0.9 % in England, 2.5 % in Taiwan, and as high as 4–10 % in some parts of Africa [8–13].

The most accepted theory attributes the development of a preauricular sinus to incomplete or defective fusion of the six hillocks of His [10].

The preauricular sinus has been described as part of a number of syndromes, most commonly branchio-oto-renal (BOR) syndrome [14, 15]. Others include brancho-oto-costal syndrome [16], cat eye syndrome [17], Waardenburg’s syndrome [18], and trisomy 22 [19, 20].

Some studies have found an association between hearing loss (conductive and sensorineural) in newborn infants with isolated preauricular tags and pits. This incidence has been reported as high as 15–30 % [21]. Interestingly, the hearing loss may evolve after a few years. However, many studies have found no statistically significant associated hearing loss with isolated preauricular sinuses and tags compared to control groups [10, 22]. The incidence of external or middle ear anomalies does not appear to be higher in patients with an isolated preauricular sinus. Conversely, individuals with congenital branchial cleft anomalies may have a higher incidence of concomitant preauricular sinus, reported as high as 60 % in the literature [23]. It is well known that patients with syndromic preauricular sinuses may have associated hearing loss as part of the clinical spectrum [24, 25].

Studies have shown an association between preauricular sinus and renal structural abnormalities. The percentage of children with isolated preauricular sinus and associated major renal structural abnormalities is reported to be 2.2–4.3 % [14, 26]. A prospective study of over 32,000 live births suggested a slightly increased risk (odds ratio 1.3) of renal anomalies in children with ear anomalies [21].

Over 50 % of cases overall are unilateral [27], although some studies have found the incidence of bilateral lesions to be 25–50 % of cases [9]. They occur more commonly on the right side [8, 10]. They are frequently noted during routine physical examination as a small pit adjacent to the external ear, usually located at the anterior margin of the ascending limb of the helix, although the opening has also been reported along the posterosuperior margin of the helix, the tragus, or the lobule [8, 28]. The extent of the depth of the pit may vary, and can be shallow, limited to the visible portion of the pit, or may form a sinus tract that can extend to a variable depth or branch or follow a tortuous course. A preauricular sinus may also result in the formation of a subcutaneous cyst. These cysts are intimately related to the tragal cartilage and the anterior crus of the helix, whereby they are always adherent to the perichondrium of the auricular cartilage [29]. Unlike the tract of first branchial arch anomalies, a preauricular sinus tract is lateral and superior to the facial nerve and parotid gland.

Patients may present with discharge from the sinus either as a result of desquamating epithelial debris or infection. The latter may manifest with erythema, swelling, pain, and discharge. The most common culture pathogens implicated in infection are Staphylococcal species and, less commonly, Proteus, Streptococcus, and Peptococcus species [9].

A preauricular sinus can be inherited or can occur sporadically. Most cases are sporadic. Bilateral cases are more likely to be inherited [9]. When inherited, the pattern is of incomplete autosomal dominance with reduced (around 85 %) penetrance [27, 30]. Research studies have mapped a possible locus for congenital preauricular fistula to chromosome 8q11.1–q13.3 [31].

Most patients are asymptomatic, and a sinus pit in a typical site is highly suggestive of the diagnosis (Fig. 2.3). A thorough history and head and neck examination are mandatory in all cases, seeking evidence of associated anomalies that may lead to the diagnosis of a syndromic etiology. Assessment of bilateral involvement, facial nerve function, and external ear development is important.

Assessment of a child with a preauricular sinus, pit, or tag entails a thorough head and neck examination as well as systems review to elicit any obvious syndromal association. Assessment of the auricle as well as otomicroscopic examination of the external auditory canal and tympanic membrane are carried out to assess for any concomitant outer ear malformations.

The necessity of performing a renal ultrasound in patients with an isolated preauricular sinus has been controversial. Some authors have recommended that renal ultrasounds be performed on all patients with isolated preauricular sinuses [14], although this view is not shared by others [28]. Compelling arguments for attaining a renal ultrasound include the low cost and risk associated with the test as well as the significant clinical implications of a detected renal anomaly. Wang et al. [21], based on a retrospective review of 42 children with external ear anomalies who had undergone renal ultrasound in two genetics medical centers between 1981 and 2000, suggested that renal ultrasound should only be performed on patients with a preauricular sinus and one or more of the following:

Routine audiometric testing in patients with an isolated preauricular sinus has also been controversial. Most of the conducted studies constituted small patient cohorts. Moreover, confounding factors, including otitis media with effusion in the young age group, make data interpretation difficult. There has been no definitive evidence that hearing assessment should be carried out in the routine evaluation of the newborn with an isolated preauricular sinus, at least no more so in these children than in those without preauricular pits.

Management of an acutely infected preauricular sinus entails administration of appropriate antibiotics active against the causative pathogen. In the case when an abscess is present, incision and drainage are commonly undertaken. This can however result in scarring that may make subsequent definitive surgical excision of the sinus more challenging. Coatesworth et al. [32] have described a technique for drainage of a preauricular abscess using a lacrimal probe, in an attempt to minimize trauma to the underlying sinus, potentially reducing the impact of fibrosis on subsequent surgical excision if needed.

Management of recurrent or persistent preauricular sinus infections usually requires surgical excision of the sinus and its tract, preferably at a time of quiescence. Various surgical techniques have been described, with the primary surgical goal of obtaining complete excision to reduce the risk of recurrence. In reviewing the literature, recurrence rates have been reported between 0 and 42 % [33, 34]. The classic approach to surgical excision involves an elliptical skin incision with removal of the skin and sinus opening and medial dissection of the sinus tract. Wide local excision in the form of a radical supra-auricular approach has also been described [34]. This approach involves a postauricular extension of the elliptical incision around the sinus opening, with subsequent medical dissection to the temporalis fascia and continued over the cartilage of the anterior helix. Tissue superficial to the temporalis fascia is removed together with the preauricular sinus as well as a portion of the cartilage or perichondrium of the helix at the base of the sinus. Studies have shown that the supra-auricular approach has a lower recurrence rate compared with simple sinus and tract excision (3.7–5 % vs. 32–42 %, respectively) [35, 36].

Currie et al. [33] carried out a retrospective review over a period of 8 years to assess risk factors that influenced recurrence rates following surgical excision of preauricular sinuses. Factors found to reduce the risk of recurrence were the use of the supra-auricular approach with clearance down to the temporalis fascia, avoidance of sinus rupture, and closure of wound dead space. To facilitate complete surgical excision, many techniques have been employed to aid in the visualization of the sinus tract and its branches. These include preoperative sonographic imaging, preoperative sinograms, intraoperative methylene blue injection, and the use of a lacrimal probe [37, 38]. These have proven to be of variable benefit, and their use is mostly dictated by surgeon preference.

Congenital aural atresia (CAA) refers to a spectrum that involves varying degrees of failure of development of the EAC.

The prevalence rates reported for CAA have been variable, reasons for which include variable registration systems and lack of a standardized definition and diagnosis [39]. Furthermore, CAA is often associated with microtia; accurately capturing CAA data from this overlapping dataset has been difficult. According to the Swedish Board of Welfare statistics, the frequency of isolated EAC malformations in 1980 was reported as 0.92 per 10,000 live births.

Failure of canalization of the EAC canal during the seventh gestational month results in membranous and/or bony CAA. The etiology of CAA, as with microtia, is multifactorial. A number of factors have been implicated in the pathogenesis, including teratogens, vascular insults, and genetic aberrations [40, 41].

Microtia is commonly associated with CAA, and the degree of auricular malformation usually correlates with the degree of CAA as well as the middle ear deformity. However, even though segments of the auricle, EAC, and ossicular chain originate from the same pharyngeal arches, they are from different segments of neural crest cells and evolve at different times in embryonic development. As such, a severe microtia with accompanying CAA is not always accompanied by a disruption in the development of the ossicular chain or middle ear cavity. Likewise, cases of a normal auricle with CAA or, albeit rarely, of microtia with normal EAC and middle ear cavity have been reported [42]. Given the separate embryologic origin of the inner ear, the incidence of inner ear abnormalities is relatively low in patients who have CAA (about 8 %) [43]. CAA has been reported in patients with chromosomal anomalies, especially terminal deletions at chromosome 18q23. A study by Veltman et al. found that atresia occurs in approximately 66 % of all patients who have a terminal deletion of 18q [44].

CAA is more commonly unilateral (70–90 %) [45]. When bilateral, the deformity on either side can vary in complexity. For unknown reasons, males are affected more commonly than females, at a 2.5:1 ratio. In addition, the right ear is more commonly involved (~60 %) [46]. CAA is more often bony than membranous, and it can be complete or incomplete. The latter may result in a stenotic cartilaginous canal laterally, with a medial osseous canal of normal caliber and a normal TM.

Several classifications have been proposed based on various parameters including clinical, radiological, surgical, and histopathological findings. A commonly used classification of CAA is that described by Weerda [47], which categorizes these malformations into three types (Table 2.1).

Altmann was the first to describe a histopathological classification correlating the severity of CAA [48] (Table 2.2). He divided three categories: mildly, moderately, and severely malformed types. Many authors have since modified this classification system, further subclassifying type II based on the surgical findings and functional outcome [49] (Table 2.3).

Schuknecht described a classification system (types A–D) based on a combination of high-resolution computed tomography (CT) scan and surgical findings (Table 2.4) (Fig. 2.4a–d).

CAA is typically evident on initial neonatal examination. The presence of microtia may draw attention to a possible associated CAA. In many countries and in all states within the United States, universal newborn hearing screening is mandatory. This has enhanced the early identification of children with more subtle presentations of CAA (e.g., unilateral CAA) who might not have been diagnosed until later in life.

In the absence of other major congenital malformations, it is most important to evaluate the status of the child’s hearing. Even if the contralateral ear is normal on newborn screening, a diagnostic auditory brainstem response (ABR) test is typically recommended in order to assure that the child has at least one normal hearing ear for access to sound and speech. Aside from audiometric assessment, any patient with CAA in whom surgical repair is contemplated should undergo high-resolution CT scanning of the temporal bones (Fig. 2.5).

In cases of unilateral CAA, hearing is typically normal in the contralateral ear [50]. Some syndromes, such as Goldenhar syndrome or hemifacial microsomia, present an important exception to this, because the uninvolved ear may demonstrate a conductive, sensorineural, or mixed hearing loss. CAA typically results in conductive hearing loss (CHL) in 80–90 % of the cases with the remaining patients demonstrating a sensorineural hearing loss (SNHL) component [5]. The CHL is typically in the moderate hearing loss range of 40–60 dB.

Current literature suggests that there are many benefits to binaural stimulation, and children with a unilateral hearing loss are at a greater risk of delayed language development, attention-deficit disorders, and poor school performance. As such, patients with unilateral CAA are currently managed with various rehabilitative options, including a hearing aid, assistive listening devices, as well as surgical correction of the atresia. In patients with complete CAA who opt to use a hearing amplification device, a bone-conduction hearing aid must be used, while in cases of incomplete CAA, an air-conduction hearing aid is also an option, but can be problematic due to difficulties in effectively fitting a stenotic ear canal. In the classroom setting, an FM system can also be an extremely effective option for children with CAA and unilateral hearing loss.

In bilateral CAA, the degree of hearing loss is usually significant enough to cause delay in speech and language acquisition and overall psychological development. It is recommended that the medical and audiologic evaluation and management of infants with CAA should follow the American Academy of Pediatrics 1–3–6 newborn hearing loss guidelines: screen by 1 month, diagnose by 3 months, and begin intervention by 6 months of age.

If surgical correction is contemplated, preoperative CT scanning provides valuable information to help in the decision-making process. In 1992, Jahrsdoerfer et al. [51] proposed a CT grading system for CAA that was shown to correlate with postoperative hearing outcomes (Table 2.5). With respect to surgical management of unilateral CAA, the risks of atresia repair should be carefully discussed with the family and weighed against the alternatives of a bone- or air-conduction hearing aid or implantation of a bone-anchored hearing aid. CAA repair carries the risks of canal restenosis, facial nerve injury, sensorineural hearing loss, and postoperative chronic otorrhea. The degree of audiometric improvement is also somewhat unpredictable following atresia surgery. Delaying surgery until after adolescence, when patients can share in their own decision-making process, is advocated by some otologic surgeons. The goal of surgery in patients with bilateral CAA is to restore sufficient hearing such that amplification is no longer needed. This typically translates to a hearing threshold of 25 dB or better. The choice of which ear to operate on is based on imaging evaluation rather than audiometric assessment. Using the Jahrsdoerfer CT grading system, in cases of unilateral CAA, a good surgical candidate scores 8 or more points. In bilateral CAA, the better ear (higher score) is chosen for repair first. With proper patient selection in cases of aural atresia, it is possible to achieve a hearing level of 25 dB or better in 50–70 % of patients. If microtia is present, its repair is first carried out as the child approaches school age (typically 5 years of age). CAA repair follows thereafter at about 6–7 years of age.

The risk of cholesteatoma development with CAA is about 4–7 % [40]. A CT scan of the temporal bones should routinely be obtained around 4 years of age. It is not recommended that a CT scan be obtained at an earlier age, as it would have to be repeated closer to the time of surgery given the ongoing growth and maturity of the temporal bone. Furthermore, the risk of cholesteatoma development under 3 years of age is minimal. This approach further minimizes unnecessary radiation exposure in the pediatric population. If cholesteatoma does exist, surgery is planned, in the form of either canal and middle ear surgery if the CT scan is favorable or canaloplasty alone.

Microtia describes a spectrum of malformations that span a wide range of clinical presentations that can affect the size, orientation, position, and morphology of the auricle. Complete absence of the auricle can also occur (anotia).

In Europe, a prevalence of 1.07 in 10,000 births for microtia and anotia was found in the period of 1980–2003 [39]. Jahrsdoerfer reported a prevalence of 1 in 5,800 births based on the Health Department statistics of the City of New York for a 10-year period (1952–1962) [52].

The etiology of microtia is often multifactorial. Only 15 % of patients have a positive family history. In a minority of patients, a genetic or an environmental cause can be found; in these cases, microtia is usually part of a specific pattern of multiple congenital anomalies.

Microtia is commonly associated with CAA, and the degree of auricular deformity correlates with the degree of middle ear deformity and conductive hearing loss. Microtia occurs in association with several single-gene disorders, such as Treacher Collins syndrome, as well as chromosomal syndromes, such as trisomy 18. It is frequently associated with the oculoauriculovertebral dysplasia spectrum of congenital anomalies, including Goldenhar–Gorlin syndrome [53]. Furthermore, microtia is a component of isotretinoin and thalidomide teratogenicity and can be part of fetal alcohol syndrome and maternal diabetes embryopathy [33]. Women with four or more pregnancies are at increased risk for having a child with microtia, especially its most severe form (anotia) [54].

As with CAA, microtia occurs more often on the right and in males. The occurrence of microtia is more common in Japanese, Hispanic, and Native American populations, but less common in the black and Caucasian populations [1, 6, 55].

Many classification systems have been proposed and modified over the years. In essence, all of the classification systems classify a normal or near-normal auricle as Grade I, with increasing grades signifying increasing deformity. Commonly used classification systems include the De la Cruz and Weerda classification systems. The De la Cruz classification divides malformations into minor and major categories (Table 2.6). In 1988, Weerda compiled all the classification systems into one scheme that is useful for clinical grading as well as basic management principles (Table 2.7) (Fig. 2.6a–c).

Microtia is evident on initial neonatal assessment. A thorough physical examination is important to accurately describe the auricular deformity, determine the status of the EAC, and assess for any associated malformations (preauricular pits/sinuses, cervical cysts, or sinuses), craniofacial malformations (ocular, zygomatic, mandibular, palatal abnormalities), as well as other organ systems. This information will be helpful in determining a possible syndromic etiology. Microtia, as with CAA, is recognized by the American Academy of Pediatrics as a high-risk factor for congenital hearing loss. It is paramount that the hearing status of a neonate with a diagnosis of microtia be promptly determined. With bilateral microtia, early referral for audiologic evaluation is critical so that proper bone-conduction hearing aid use can be implemented. With unilateral microtia, a diagnostic ABR test is typically recommended to ensure that the child has at least one normal hearing ear. If there is associated CAA and surgical correction is contemplated, a preoperative CT scan is recommended.

Management of microtia is commonly a multidisciplinary approach. If other congenital anomalies are present, either in association with a syndrome or as isolated findings, consultation from the appropriate services is indicated. From an otologic perspective, one must initially determine what type of auditory habilitation is required and feasible. Patients with microtia associated with CAA follow the algorithm previously discussed under CAA, as auditory habilitation of the associated CHL takes precedence in these cases. If surgery is contemplated, microtia repair is undertaken at approximately 5–6 years of age, with atresia repair following at approximately 6–7 years.

Using the Weerda classification, first-degree dysplasia encompasses many common and frequently isolated auricular malformations, including macrotia, protruding ears, and cup ear deformity. Reconstruction normally does not require the use of additional skin or cartilage. Instead, many otoplastic techniques have been described that attempt to achieve some auricular reduction. These techniques for the most part involve manipulation of the cartilage framework by using sutures or by cutting, abrading, or scoring. Examples of the former include the Mustarde and the Furnas techniques. Examples of the cartilage-cutting techniques include the Converse, Farrior, and Pitanguy techniques. These techniques make use of the observation that cut cartilage bends away from its cut side. Cartilage cutting is useful for manipulating cartilage that is stiff and thick but can cause scarring, irregularities along the cut edges, and a diminished auricle size. They are also generally more difficult to undertake and require an experienced surgeon for their maximal benefit and utilization.

Second-degree dysplasia, or atypical microtia, has most of the auricular structural components recognizable; there is however distinct tissue deficiency that necessitates the transposition of skin and cartilage. The main deficiency often lies in the vertical height of the affected ear. Augmenting this deficiency can be achieved by various techniques depending on the difference in height between the two ears. If the height difference is more than 20 mm, a cartilage graft is considered. Donor sites include the contralateral conchal bowl or a rib graft for large deficiencies. A staged skin graft in these instances is often required and may be advanced from a postauricular donor site.

Reconstruction for third-degree dysplasia (classic microtia) or anotia requires the use of skin and large amounts of cartilage. This is best initiated at the age of about 6 years, especially for unilateral cases, and the best donor tissue is autogenous costal cartilage. By this age, sufficient cartilage is present for the auricular reconstruction, and the patient is more able to cooperate with the necessary postoperative care. The reconstruction is multistaged and incorporates CAA repair.

The tympanomastoid compartment first appears at the 3-week stage as an outpouching of the first pharyngeal pouch (the tubotympanic recess) (Fig. 2.7). This is a stalklike diverticulum, which expands in a lateral direction until it comes in contact with the epithelial lining of the first pharyngeal cleft. The distal part of this diverticulum widens into a saclike structure, which is the primitive tympanic cavity. Expansion of the pouch begins at the inferior aspect of the definitive tympanic cavity and progresses by invasion of the adjacent mesenchyme. By 7 weeks, concomitant growth of the second branchial arch constricts the importation of the tubotympanic recess. The primary tympanic cavity lies lateral to this constriction, while the proximal part of the tubotympanic recess medial to this constriction remains narrow and develops into the Eustachian tube. The distal end of the first pharyngeal pouch buds into four sacci (anticus, posticus, superior, and medius), which expand to progressively pneumatize the middle ear and the epitympanum. Expansion of the sacci envelops the developing ossicles, which remain embedded in mesenchyme until the eighth month, when the surrounding tissue dissolves. The interface between two sacci gives rise to mesentery-like mucosal folds, which transmit blood vessels. Mesenchymal resolution may continue as late as 1 year postnatally (or even later in some rare cases). Persistence of this embryonic connective tissue in the adult may be evident as connective tissue strands draped over the oval and round windows.

By birth, the antrum approximates that of the adult. Mastoid pneumatization is evident as early as 33 weeks gestation and proceeds along well-established tracts. There is considerable variability amongst individuals in the degree and pattern of temporal bone pneumatization, and multiple factors are thought to play a role in this, including heredity, environmental, nutritional, infectious, and anatomic factors relating to the adequacy of ventilation by the Eustachian tube. Overall, the mastoid continues to grow for up to 19 years after birth.

The ossicular chain largely has its origins traced back to the pharyngeal arch apparatus, and studies have established that it is the phylogenetic equivalent of the jaw joint in all nonmammalian jawed vertebrates [56]. In these animals, the jaw joint is established between mesenchymal components of the first and second pharyngeal arches, namely, the quadrate and articular portions. In the typical living reptile, sound is transmitted through the columella auris from a primitive tympanic membrane to the inner ear [57]. During evolution, the jaw joint was modified, and the articulo-quadrate joint evolved to constitute the mammalian middle ear [58]. The articular became the malleus and the quadrate the incus. These ossicles, through their respective contacts with the tympanic membrane and stapes (the phylogenetic homolog of the columella auris), were incorporated into the sound-transmitting apparatus [59, 60].

The first evidence of ossicular development occurs at approximately 4 weeks. An interbranchial mesenchymal bridge appears between the first and second pharyngeal arches. Specifically, the bridge connects the upper end of a part of the first arch (referred to as the mandibular visceral bar) with the central region of the second pharyngeal arch (hyoid) visceral bar. Thus, this condensed mesenchymal bridge consists of both first and second pharyngeal arch elements, which ultimately undergoes cartilaginous differentiation that gives rise to the primordial malleus and incus. As for the stapes, all of its blastula derives from the hyoid visceral bar except for the medial surface of the footplate and the annular ligament, which are of otic capsular (lamina stapedialis) origin. Thus, the ossicles are derived from neural crest mesenchyme of the first and second branchial arches, with the only exception being the medial aspect of the stapes footplate and the annular ligament, which are derived from the mesenchyme of the otic capsule.

Over the following 11 weeks, the ossicles develop and grow as a cartilaginous model of the mandibular and hyoid arches. This process is bone formation from a cartilaginous framework and is referred to as endochondral ossification. The anterior process of the malleus is unique in that it develops by membranous ossification without a cartilaginous model. Although controversy exists as to the exact contribution of each arch to the ossicular chain, it is believed that the head of the malleus as well as the body and short process of the incus are formed from Meckel’s cartilage. Meanwhile, the long process of the incus, handle of the malleus, stapes superstructure, and tympanic surface of the stapes footplate are derived from Reichert’s cartilage. As previously mentioned, the medial surface of the footplate and the annular ligament are of otic capsular origin. Development of the stapes blastema involves progressive encirclement of the stapedial artery. The obturator foramen represents the completed ring left empty after the stapedial artery involutes.

By 15 weeks of gestation, the ossicles have already attained adult size, and the process of endochondral ossification soon begins. This process starts first in the incus, then in the malleus, and finally in the stapes. As the footplate attains adult size, the annular ligament is formed from the developing otic capsule. Paralleling this development, the tensor tympani and stapedius muscles develop. The tensor tympani muscle is innervated by the mandibular branch of the trigeminal nerve, the nerve of the first pharyngeal arch, while the stapedius muscle is innervated by the facial nerve, the nerve of the second pharyngeal arch. By 20 weeks gestation, the ossicles have assumed their adult configuration, and the endochondral bone of the ossicles, as with that of the otic capsule, undergoes little change over the lifetime of the individual. The exception to that is the stapes, which continues to lose bulk from its large structure well into the 32nd week of gestation. The stability of the ossicular bone explains the poor reparative capacity in response to trauma.

Although the ossicles appear during the first half of fetal life, they remain embedded in mesenchyme until the eighth month, when the surrounding tissue dissolves. As the mesenchyme surrounding the ossicles dissolves and the developing tympanic cavity expands, the endodermal epithelial lining of the primitive tympanic cavity then extends along the wall of the newly developing space to the epitympanic space and antrum and envelopes the developing ossicles. The tympanic cavity is now at least twice as large as before. When the ossicles are entirely free of surrounding mesenchyme, the endodermal epithelium connects them in a mesentery-like fashion to the wall of the cavity. The supporting ligaments of the ossicles develop later within these mesenteries.

During late fetal life, the tympanic cavity expands dorsally by vacuolization of surrounding tissue to form the tympanic antrum. After birth, epithelium of the tympanic cavity invades bone of the developing mastoid process, and epithelium-lined air sacs are formed (pneumatization). Later, most of the mastoid air sacs come in contact with the antrum and tympanic cavity.