Congenital malformations of the external and middle ear often occur simultaneously. The former results from underdevelopment of the first and second branchial arches and the first branchial groove. The latter is associated with underdevelopment of the first pharyngeal pouch, which can lead to malformations of the tympanic cavity, eustachian tube, and even the mastoid. Clinically, they are commonly referred to as congenital microtia.
Clinical manifestations
The Marx classification is commonly used for categorizing external ear malformations:
- Type I: Mild deformity with a slightly smaller auricle, but structures clearly recognizable
- Type II: Moderate deformity with a smaller auricle and partial retention of structures
- Type III: Severe deformity with only partial auricular cartilage and lobule remaining
- Type IV: Anotia (absence of the ear)
Figure 1 Marx classification of external ear malformations
The Jahrsdoerfer scoring system is currently the standard for scoring middle ear malformations. It uses a 10-point grading system based on high-resolution temporal bone CT scans and otological examinations. The stapes' morphology and function receive 2 points, while the development of the external auditory canal, vestibular window, tympanic cavity, facial nerve, malleus-incus complex, incus-stapes connection, mastoid air cells, and cochlear window each receive 1 point.
Figure 2 Jahrsdoerfer scoring on temporal bone CT
1, External auditory canal; 2, Malleus-incus complex; 3, Incus-stapes connection; 4, Stapes; 5, Vestibular window; 6, Cochlear window; 7, Facial nerve; 8, Tympanic cavity; 9, Mastoid air cells
Diagnosis
A preliminary diagnosis can be established based on the presence of ear malformations at birth. Hearing tests are necessary to determine the nature of hearing loss. Conductive hearing loss is an indication for surgery. Thin-slice CT or spiral CT scans of the temporal bone can assess mastoid pneumatization, middle ear cavities, ossicular malformations, and external auditory canal atresia, providing a basis for malformation grading and surgical treatment.
Treatment
For unilateral malformations with normal hearing in the opposite ear, surgery is typically performed at 6-8 years of age.
Unilateral external auditory canal atresia with infectious fistula or cholesteatoma formation may require earlier surgery based on specific circumstances.
Bilateral malformations with moderate or severe conductive hearing loss should undergo surgery on the less severely affected ear as early as possible (generally after 2 years of age) to improve hearing and promote speech and intellectual development. Alternatively, a soft band bone conduction hearing aid can be worn until surgery.
Management of congenital auricular and middle ear malformations involves reconstructive surgery of the malformed auricle, as well as hearing restoration and rehabilitation.
Common techniques for total auricular reconstruction include:
- Staged ear reconstruction using autologous rib cartilage
- One-stage ear reconstruction with a superficial temporal fascia flap
- Staged or simultaneous ear reconstruction with skin expansion in the mastoid area
Patients with congenital auricular and middle ear malformations, accompanied by external auditory canal atresia or stenosis, and conductive hearing loss, require surgical hearing restoration. There are two main approaches:
- External auditory canaloplasty and tympanoplasty
- Artificial auditory implants, including bone-anchored hearing aids, vibrant soundbridge, and bonebridge
Patients with Jahrsdoerfer scores above 6 may be candidates for external auditory canaloplasty, while scores of 5 or below are not recommended for surgery. For unilateral external auditory canal atresia or stenosis with severe sensorineural hearing loss in the opposite ear, and for patients with bilateral atresia or stenosis who are unsuitable or unwilling to undergo surgery, bone conduction hearing aids can be implanted or worn.