Several classification schemes have been described to define the severity of canal atresia as well as to predict the likelihood of successful hearing restoration surgery. Classification systems can be helpful in choosing appropriate surgical candidates, in counseling patients, and in analyzing and comparing results. The first widely used classification system, descriptive in nature, was proposed in 1955 by Altmann16 (Table 22-2). In 1985 De la Cruz13 proposed a further classification of Altmann groups

II and III into major and minor categories (Table 22-3), proposing that patients with only minor malformations stood a reasonable chance at hearing restorative surgery, whereas patients with major malformations had a low chance of success from

FIGURE 22 —1 Normally developed ear, showing usual course of the facial nerve. I, incus; M, malleus; TMJ, temporal mandibular joint; VII, facial nerve.

FIGURE 22-2 Aberrant anatomy in an atretic ear, with a fused malleus-incus complex as well as anterior and superior displacement of the facial nerve. VII, facial nerve.

Table 22-2 Altmann Classification of Congenital Aural Atresia

Group I (mild)

Group II (moderate)

Group III (severe)

External auditory canal (EAC) is present, although hypoplastic; tympanic bone is hypoplastic, and the tympanic membrane is small; tympanic cavity is normal or hypoplastic

EAC is absent; tympanic cavity is small and its contents are malformed; an atretic plate is present and ossified EAC is absent; the tympanic cavity is missing or severely hypoplastic

Table 22-3 De La Cruz Classification of Congenital Aural Atresia

Minor malformations (candidates for hearing restorative surgery)

Normal mastoid pneumatization Normal oval window

Reasonable oval window-facial nerve relationship Normal inner ear

Major malformations (candidates for bone-anchored hearing aids)

Poor mastoid pneumatization Abnormal or absent oval window Abnormal facial nerve course Inner ear abnormalities

FIGURE 22-2 Aberrant anatomy in an atretic ear, with a fused malleus-incus complex as well as anterior and superior displacement of the facial nerve. VII, facial nerve.

surgery, and were better managed by bone-anchored hearing aids to overcome their conductive hearing loss. Perhaps the most widely used classification system used to qualify patients for potential hearing restorative surgery is one proposed by Jahrsdoerfer et al11 in 1992 (Table 22-4). A 10-point grading system evaluating a variety of middle and external

Table 22-4 Jahrsdoerfer Grading System of Candidacy for Surgery of Congenital Aural Atresia



Stapes present Oval window open Middle ear space Facial nerve normal Malleus-incus complex present Mastoid well pneumatized Incus-stapes connection Round window normal Appearance of external ear Total available points

Rating/Candidacy 10 9 8 7 6

Excellent Very good Good Fair

Marginal Poor ear structures as seen on high-resolution computed tomography (HRCT) scanning is used to predict the likelihood of success of hearing restoration surgery. Patients receiving total scores of 5 or below are not candidates for surgery, whereas patients scoring 6 or higher are considered for surgery.

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