Congenital Abnormalities of the Ear

7/28/2019 Congenital Abnormalities of the Ear.

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6.1.1 CONGENITAL ABNORMALITIES OF THE EAR

Embryology

External ear starts to form in 4th week

By 6th week = 3 anterior hillocks from 1st branchial arch, + 3 from 2nd

branchial arch Between the 2 lie the 1st brachial cleft externally and 1st pharyngeal pouch

internally.

1st brachial cleft Ext auditory meatus

Lower anterior hillock tragus

Middle ant hillock crus of helix

Upper ant hillock major part of helix

Lower post hillock lobule and lower helix

Middle post hillock antitragus

Upper post hillock antihelix

Initially the ear is sited in the lower neck region but as the mandible

develops they ascend to the side of the head at the level of the eyes.

Last printed 3/05/2006 21:13:00 a5/p5 - 1 /var/www/apps/conversion/tmp/scratch_3/139859979.doc


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Blood supply

Post auricular artery br of external carotid, runs up in sulcus behind ear,supplies post skin and lobule.

Superficial temporal artery terminal br of ext carotid. Runs up in front ofear auriculotemporal nerve.

Occipital artery dominant supply to the posterior ear in 10% of people.

Nerve Supply

Great auricular (not Greater - there is no such nerve) Sensation to innerand outer aspects of lower half of ear

Auriculotemporal(V3) Sensation to outer aspect of the superior half

Lesser occipital Sensation to inner aspect of superior half

Auricular branch of Vagus (Arnolds or Aldermans nerve) Sensory toconchal fossa + ext auditory meatus

o Stimulation of nerve cold then warm water to conchal fossainduces vagal-induced vomit.

o (Also prev know as Aldermans nerve as Anglo-saxon nobles put

cold water in their ears to induce vomiting so they could eat more!)

Regional Block



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Classification of Congenital Ear Deformities

Tanzer1975 classified auricular deformities

Type 1 = anotiaType 2 = microtia with atresia of the external

auditory meatusType 2B = microtia without atresia of EAM

Type 3 = Hypoplasia of the middle-third of the earType 4

Type 4A Constricted ear lop/cup/pixieType 4B = CryptotiaType 4C = Hypoplasia of the entire upper-third of the ear

Type 5 = Prominent Ear

(Stahls Ear Extra Crus)

Nagata Classification Lobule Type, Concha Type & Small Concha Type of Microtia andAnotia

Anotia

= total absence of the ear

Incidence = 1 in 6000 Western world, 1 in 4000 Japan, 1 in 1000 NavajoIndians

Male-to-female ratio is 2.5:1. Microtia typically is unilateral rather thanbilateral (unilateral-to-bilateral ratio of 4:1). The right ear is affected more

frequently than the left ear (right-to-left ratio of 3:2).



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Associations with Hypoplastic conditions

Treacher Collins (bilateral anotia usually)

Hemifacial Microsomia (usually unilateral anotia) - Goldenhars Syndrome (Hemifacial + Eye)


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Congenital Abnormalities of the Ear