SOURCE: Dept. of Otolaryngology, UTMB, Grand Rounds
DATE: May 1, 1996
RESIDENT PHYSICIAN: Ramtin Kassir
FACULTY: Karen A. Calhoun, M.D.
SERIES EDITOR: Francis B. Quinn, Jr., M.D.
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"This material was prepared by resident physicians in partial fulfillment of
educational requirements established for the Postgraduate Training Program of
the UTMB Department of Otolaryngology/Head and Neck Surgery and was not intended
for clinical use in its present form. It was prepared for the purpose of stimulating
group discussion in a conference setting. No warranties, either express or implied,
are made with respect to its accuracy, completeness, or timeliness. The material
does not necessarily reflect the current or past opinions of members of the UTMB
faculty and should not be used for purposes of diagnosis or treatment without
consulting appropriate literature sources and informed professional opinion."
The auricle and the external auditory canal are derived from the first and
second branchial arches. These arches differentiate into the six auricular
hillocks, three from the first arch and three from the second. By the sixth
week of embryologic development, these hillocks have fused to form the
auricle of the ear. Abnormalities in this developmental sequence result in
deformities of the external ear. Microtia results when the deformed ear is
too small. Various classification systems exist for microtia; the scheme
described by Aguilar and Jahrsdoerfer include:
Grade I - normal ear
Grade II- some of the auricular framework is present,
but there are obvious deformities
Grade III- peanut ear deformity, which
In the adult the ideal auricle is approximately 5.5-7.5 cm high and about
half as wide. It attaches on the lateral aspect of the head between
horizontal lines drawn from the nasal spine and the superior aspect of the
orbit. Normally the ear protrudes 30 degrees from the mastoid, and ideally
inclines approximately 20 degrees posterior from the vertical.
The normal contours of the ear are created largely by the underlying elastic
cartilage and include: helix - a ridge of cartilage that forms the superior
and posterior rim of the auricle, and continues anteriorly as the crus of the
helix and extends inferiorly to join the lobule antihelix- a Y shaped
cartilage of major support that extends from the antitragus inferiorly,
widening superiorly into a superior and inferior crus triangular fossa- the
area formed between the inferior and superior antihelical crura scapha - the
area formed posterior to the superior antihelical crus concha - the large
central concavity of the lateral surface of the ear, bounded by the
antitragus and the inferior crus of the antihelix. The helical crus divides
the concha into a concha cymba superiorly and a concha cavum inferiorly.
Careful preoperative planning is essential in repair of microtia. Correction
should usually begin at about age 6, especially for unilateral cases. At
this age the child has not been exposed to cruel teasing and there is
sufficient cartilage for framework fabrication. Furthermore, the child at
this age is aware of the problem, wants it resolved, and is able to manage
the necessary postoperative care. Forty five percent of patients in a series
by Brent underwent reconstruction between the ages of five and seven. The
size of the opposite normal ear can influence the timing of repair; if the
other ear is large and the child is small, the surgery may have to be
postponed for several years. Bilateral microtia and atresia cases may be
started at an earlier age, but according to Brent beginning surgery prior to
age 51/2 creates technical handicaps and poor patient cooperation.
Preoperative photographs are essential. In cases of microtia with atresia,
radiologic exam (CT scan) prior to surgery provides useful information to the
surgical team. To completely assess middle ear development, axial and
coronal planes are necessary. If normal sensorineural function has been
established preoperatively, the otologist can then assess middle and inner
ear development and plan the third stage of the reconstruction. Auricular
reconstruction is performed before the atresia repair as this ensures a
virgin field without scars and compromised blood flow for the implanted
auricular framework. Also, the cosmetic result is limited if the auricle has
to be reconstructed around a bony canal drilled in the temporal bone.
Method of Repair
Autogenous cartilage is best since it has withstood the test of time.
Irradiated cartilage reabsorbs; silastic tends to extrude with time and does
not withstand trauma. In cases of congenital microtia and concomitant
atresia, the surgical team should consist of the plastic surgeon and the
At birth the size of the ear is roughly 3/4 of normal and reaches full adult
size by age 14. It has been shown by Tanzer that sculpted rib cartilage
grows and keeps pace with the normal earís growth. Therefore it is not
necessary to construct the graft any larger than the normal ear, rather, it
should be made the same size or slightly smaller.
First Stage ( Framework fabrication and insertion)
A film pattern is traced from the normal ear and reversed to plan the new
framework. In unilateral microtia, the position of the vestige from the
lateral canthus is approximately the same as the normal earís helical root
from the lateral canthus. If the patient has a low hairline, then it can
either be adjusted after the reconstruction is completed or a smaller
framework can be made and the opposite normal ear reduced.
When harvesting the rib cartilage, a chest incision is made on the side
opposite the microtia. The first free floating rib is used for the helix and
the synchondrosis of ribs 6 and 7 for the framework body. The framework is
made slightly smaller (especially inferiorly) to accomodate the overlying
skin and the future lobule. The triangular fossa and scapha are marked and
carved using a No. 5 Paget gouge and a 15-C blade. All framework details are
exaggerated, especially if the overlying skin is thick. The outer
perichondrium on the framework body is preserved to allow nourishment from
surrounding tissues. The outer perichondrium of the helical cartilage is
trimmed to encourage warping in the proper direction. This is then sewed to
the framework using mattress sutures of 4-0 nylon with the knots buried. A
small preauricular incision is then made and the vestigial cartilage removed;
the pocket is undermined to the extent that the framework may be inserted
under tension free conditions. Brent advocates placing silicone drains
beneath and posterior to the framework. Postoperatively, no pressure
dressings are used and the drains are left in for 3-4 days.
Second Stage (Lobule transposition)
This stage involves lobule transposition and is performed several months
after the framework is inserted. The lobule remnant is raised as an
inferiorly based flap by incising around it; an incision is also made at the
proposed superior inset margin. To avoid excessive protrusion of the lobule,
the superior posterior incision on the back of the ear should be made fairly
high. The vestigial tissue is excised from the fossa triangularis at this
time. If no lobule exists, then one is created from the framework and
defined later when the ear is lifted from the head.
Third Stage (Atresia repair)
Once normal sensorineural function has been established, the decision to
operate depends primarily on the degree of middle ear development, as
reflected by the size of the tympanum and status of the ossicles. The facial
nerve usually has an anomolous course in aural atresia and it is monitored
intraoperatively; failure to identify it clearly on CT preoperatively is not
a contraindication to surgery. The ideal surgical candidate is one whose
mastoid and middle ear size are at least two thirds of the normal size and if
all three ossicles, although deformed, can be identified. Furthermore, CT
should demonstrate the round and oval windows and a near normal or normal
course of the facial nerve. Minimal criteria are presence of an ossicular
mass and a middle ear of at least one-half normal size. Ideal candidates are
selected for unilateral atresia cases; minimal criteria may be used in
bilateral atresia cases.
The two basic techniques used are the mastoid and the anterior approach. In
the mastoid approach, the sinodural angle is identified and followed to the
antrum. The atretic bone is removed after the facial recess is opened and
the I-S joint is separated. In the anterior approach, drilling is confined
to an area bound by the TMJ anteriorly, the middle cranial fossa dura
superiorly, and the mastoid air cells posteriorly. The problems of a large
mastoid cavity are thus avoided and there is less surgical manipulation in
the mastoid segment of the facial nerve. Once the atretic bone is removed, a
fascia graft is placed over the mobilized ossicular chain. Hearing results
are usually better if the chain is left intact instead of using interposition
prostheses. A meatoplasty is then performed and aligned with the bony canal.
Finally, the bony canal is skin grafted and stabilized with antibiotic
Stage four (Tragal reconstruction)
A composite chondrocutaneous graft is harvested from the normal earís conchal
bowl and applied beneath a tragal flap developed by means of a J-shaped
incision. The donor site is skin grafted if primary closure caused
distortion of the normal ear. To accentuate conchal depth beneath the tragal
flap, excess soft tissues in the bowl are excised.
Stage five (Auricular elevation)
An incision is made posterior to the auricular margin and the ear is elevated
while preserving connective tissue on both the cartilaginous undersurface and
the bony floor. The postauricular scalp is undermined and advanced to the
sulcus to decrease the area to be skin grafted. These grafts are harvested
from the lateral hip or buttocks areas and applied to the back of the ear and
The most common complication that can occur from stage I is atelectasis.
Pneumothorax, pneumomediastinum, pleural tear occur much less frequently. If
the framework is inserted under tension, necrosis of the overlying skin can
occur; hematoma and/or infection may lead to chondritis with subsequent graft
loss. Furthermore, malposition of the framework may occur and the
possibility of keloid formation always exists.
Brent, B. Auricular Repair with Autogenous Rib Cartilage Grafts: Two Decades
of Experience with 600 Cases. Plast. Reconstr. Surg. Sept 1992, 355-374.
Aguilar, EA III. Major Congenital Malformations of the Auricle. In Head and
Neck Surgery-Otolaryngology, edited by Byron J. Bailey, pp 1535-41.
Lambert, PR. Congenital Aural Atresia. In Head and Neck
Surgery-Otolaryngology, edited by Byron J. Bailey, pp 1579-1591.
Tanzer, RC. Microtia: A Long Term Follow-up of 44 Reconstructed Auricles.
Plast. Reconstr. Surg. 61: 161, 1978.