Developmental disorders of the ear

The outer and middle ear develop separately from the inner ear. Therefore, we can divide congenital ear defects into congenital defects of the outer and middle ear and congenital defects of the inner ear.

Congenital defects of the external and middle ear

Abnomalies of the external and middle ear are related to the maldevelopment of the first gill slit and the first two gill arches . These diseases are manifested by shape deformities of the auricle and ear canal. They can occur together with dysostoses of the lower jaw, zygomatic bone and auditory ossicles .

Congenital malformations of the auricles relate to shape, size and position.

Otapostasis

The most common congenital defect is otapostasis , the so-called standing bolt. It is an inherited, frequent defect of the auricle, the essence of which is the smoothing of the fold of the antihelix. The defect can be corrected surgically (the most suitable time for correction is between 5 and 6 years). The principle is the creation of a new antihelix.

Microcia

Another very common defect is microcia , i.e. reduction of the auricle. The defect can be classified into 3 degrees, in the case of the 2nd and 3rd degrees, the bolt is not only reduced in size, but also deformed in shape.

Anocia

Anocia is the complete failure of the auricle to develop.

Appendices preauriculares

Appendices preauriculares are usually unilateral appendages of the pinna . They mostly have the shape of bumps or pedunculated lobes located in front of the tragus.

Congenital ear fistula

These are canals mainly in the ascending part of the helix, external fistulas are less common, on the neck they are colo-auricular fistulas. Their danger lies in possible secondary infection, so they need to be surgically removed.

Stenosis and atresia of the ear canal

Stenosis is a narrowing of the ear canal. Atresia is a complete closure of the ear canal - the ear canal is completely impassable. Atresia can be both bony and fibrous. It is the cause of conductive hearing loss. Both defects (stenosis and atresia) can be associated with other defects (auricle disorder, middle ear disorder, facial nerve disorder ). The therapy is surgical . It consists in the canalization of the ear canal, or the reconstruction of the middle ear.

Failure to form an antihelix
Antihelix after reconstruction
Detail of MICROTIA (outer ear deformity). Subject is photographer's son Gage, age 8 months at time of photo. Gage exhibits a Level-III microtia (the most common) on his left side, with no ear canal visible from external. Testing has proven aural nerve intact, meaning he can hear on this side. Further testing will be done at a later age to determine surgery possibilities. Right ear is normal.
This newborn with an atretic right ear, is displaying an anomaly included in VACTERL Association. VACTERL association or a nonrandom association of specific newborn abnormalities include to name a few, vertebral dysgenesis, anal defect, cardiac anomalies, tracheoesophageal fistulae, esophageal atresia, radial limb and renal anomalies.

Congenital defects of the inner ear

Anomalies of the inner ear are caused by disorders of otocyst formation . Different types of labyrinth hypoplasia arise due to a disorder in the development of the otocyst.

The Mondini Anomaly

A normal snail has 2.5 turns. In the case of Mondini's anomaly , the cochlea has only 1 turn and there is a pathological communication between the scala vestibuli and the scala tympani with simultaneous expansion of the saccus and ductus endolymphaticus .
Hearing impairment varies in extent.
Diagnosis is mainly based on CT .

Complex congenital disabilities

Treacher- collins syndrome front view

The ear is often affected within specific syndromes. The best known is the so-called Treacher-Collins syndrome .

Treacher-Collins syndrome

It is an AD disease. Mental development is not affected in this syndrome. Typically found here:

antimongoloid position of eye slits with coloboma,
hypoplasia of cheekbones and mandible ("bird profile"),
malformation of the ear,
macrostomia,
high floor.

Links

Zdroj

References

KLOZAR, Jan, et al. Speciální otorinolaryngologie. 1. edition. Praha : Galén, 2005. pp. 224. ISBN 80-7262-346-X.

Kategorie:Otorhinolaryngology Kategorie:Pediatrics Kategorie:Genetics