The surgical management of congenital pre-auricular sinus

Patrick Chapman

E.N.T. Depurmmt. St. Peter:$ Hqml, Chertur,: Sunw KTlh OP_’ 11;. K ,

(Received January 2 1 st. 198 I ) (Accepted July 27th. I98 I )

Summary

The gross anatomy of pre-auricular sinuses is discussed and illustrated. Previously

described methods to aid complete excision are discussed and a new surgical

approach which facilitates the total excision of a pre-auricular sinus is recorded. Knowledge of the sometimes extensive nature of a pre-auricular sinus with both

pre-auricular and post-auricular tracts is necessary to obtain complete excision. The technique described allows extensive subcutaneous exposure of the sinus, excision of

skin where necessary and also primary closure.

Introduction

The aetiology, incidence and sites of the cutaneous orifices of congenital pre-

auricular sinuses are well described [ 1,2]. It is usually stated that complete excision is

the correct management of a pre-auricular sinus although little is written about the

gross anatomy of the sinuses. This paper describes the anatomy of pre-auricular

sinuses and discusses some techniques used to facilitate complete excision of the sinus which include pre-operative X-ray sinography [ 171, peroperative injection of

the sinus with methylene blue [9] and the use of the operating microscope [ 11. It was found that these techniques were either unnecessary or unsatisfactory and a new and

simple technique of ensuring complete excision of the sinus is described.

Material

The paper is based on the experience drawn from a personal series of 6 patients treated during a period of two years. Two patients underwent bilateral operations and there were no recurrences in a follow-up period of two years or more. The chnical histories of each case are summarized in Table I.

01~5-5X7h/X2,/(X)00-0000/$02.75 C 1982 Elsevier Biomedical Press

TA

BL

E

I

CL

INIC

AL

H

IST

OR

IES

OF

TH

E

6 PA

TIE

NS

OF

TH

E

PRE

SEN

T

ST

UD

Y

Patie

nt

Sex

Age

E

ar

Dur

atio

n E

xten

t Pr

evio

us

Follo

w-u

p

of

sym

ptom

s of

si

nus

surg

ery

peri

od

1 F

36

righ

t 3

mon

ths

exte

nsiv

e in

cise

d 27

m

onth

s

2 F

17

both

3

year

s ex

tens

ive

none

42

m

onth

s

3 M

26

le

ft

som

e ye

ars

exte

nsiv

e pr

evio

us

exci

sion

41

m

onth

s

4 M

12

ri

ght

3 ye

ars

exte

nsiv

e no

ne

29

mon

ths

5 M

8

both

si

nce

birt

h ex

tens

ive

none

40

m

onth

s

6 F

26

left

5

year

s ex

tens

ive

none

24

m

onth

s

The symptoms experienced were those of intermittent purulent discharge from the sinus frequently associated with a tender painful pre-auricular swelling. One patient had undergone incision and drainage of a pre-auricular abscess prior to referral. Patient 3 in Table1 had undergone an operation by another surgeon one year previously who had used the methylene blue dye injection technique to assist sinus localization. At the revision operation it was clear that the previous surgery had only partially resected the pre-auricular sinus and 4 tracts of the sinus remained in situ. No complications of the procedure were experienced in the cases reported.

Anatomy

Auricular sinuses and pre-auricular sinuses usually occur alone and they are infrequently associated with accessory auricular tags and abnormalities of the pinna. The possible sites for the cutaneous orifice of auricular sinuses have been reported by Congdon [2] but a majority open in the pre-auricular region as indicated in Fig. 1. Auricular and juxta-auricular sinuses are of variable size [2] but in all the patients reported here the ‘pre-auricular sinus’ consisted of a sinus sac with a number of tracts projecting from it extending in anterior and posterior directions. (Fig. 2) In the two bilateral operations there was a close correlation between the shape and extent of the sinuses on the two sides. Sinus tracts extending anteriorly were common; an important finding in all the ears that underwent operation was that of a relatively

Fig. I. Illustrates a typical pm-auricular sinus. The continuous line ‘i’ indicates the incision used and the

arrow indicates an elipse surrounding the common site for a cutaneous orifice of the sinus.

Fig. 2. Illustrates the tracts radiating from the sinus body. I. a commonly found post-auricular extension:

2, tract connected to the antihelix; 3. tract connected to the external cartilagenous meatus: 4. tracts

radiating anteriorly. The arrow indicates the sinus body.

large tract running posteriorly towards the mastoid process. Fig. 3 illustrates an abscess of such a tract in a patient that had a congenital auricular tag, a congenital auricular sinus and a normal middle ear cleft. In 4 of the ears there was a tract running posteriorly and medially where in 3 patients the tract connected with the anterior cartilagenous wall of the external auditory meatus and in the fourth patient the tract opened into the lumen of the external auditory meatus. In 4 of the ears there was also a connection to the cartilage of the antihelix.

The sinus and its tracts lie in the subplatysmal plane immediately superficial to the parotid gland and temporalis fascia lying in close relationship with the

Fig. 3. Illustrates an abscess in a sinus tract which lies over the mastoid process. The arrow indicates the

cutaneous orifice of the auricular pit.

superficial temporal artery. Tracts of the sinus may lie close to the facial nerve in two regions. The trunk of the facial nerve may be damaged whilst resecting a tract which runs posteriorly and medially to its connection with the cartilagenous external auditory meatus. Branches of the facial nerve may be damaged whilst resecting tracts which run anteriorly and extend beyond the border of the parotid gland.

Embryologically the ear develops from 6 primary ear tubercles, 3 being on each of the first and second branchial arches. The tragus and part of the helix originate from those tubercles on the first arch whilst the rest of the pinna is derived from the tubercles of the second arch. Opinions vary [2,14] on the embryological development of an auricular sinus but the intertubercular hypothesis of His [7] is the most acceptable description of the development to date. The sinus is described as developing from a groove between 2 of the 6 primary ear tubercles and results from incomplete fusion of the tubercles in the early stages of development.

Surgical Procedure

The operation is performed under general anaesthesia and a strip of scalp is shaved in the temporal region to facilitate performing the incision illustrated in Fig. 1. The incision commences in the temporal region, runs caudally in front of the pinna excising the cutaneous orifice of the pre-auricular sinus extending to a level in front of the ear lobule. Exposure of the sinus is achieved by dissecting down to temporalis fascia superiorly, and extending this plane of dissection in an inferior direction until the upper border of the sinus sac is exposed. The deep surface of the sinus is dissected from from the temporalis fascia and the parotid gland (Fig. 4).

Fig. 4. Illustrates the upper border of the pre-auricular sinus lying on temporalis fascia and the sinus

being dissected on the deep surface from above.

20

Commencing superiorly each tract of the sinus may then be individually followed to its termination and the sinus fully excised. The superficial temporal artery will need to be dissected free and preserved or be ligated. Haemastasis is obtained, the skin flap replaced and the skin is closed in layers using a redivac suction drain.

If it was necessary to excise a significant amount of facial skin with the sinus, primary skin closure is possible as skin mobilisation occurs during the anterior dissection of the sinus tracts and this may be extended if necessary, as in rhytidec- tomy, to allow primary closure. Haematoma formation is the most significant postoperative problem. No complications occurred in the small series reported but the proximity of the facial nerve is discussed later.

Discussion

Pre-auricular sinuses are inherited as an incompletely dominant autosomal gene with variable penetrance. [3,4,14] The association between pre-auricular sinuses and other abnormalities is well reported [4,6,8,10,1 l] and the author has treated a patient with Marfan’s syndrome situs inversus and bilateral pre-auricular sinuses.

Commonly pre-auricular sinuses occur unassociated with other abnormalities. Some pre-auricular sinuses remain asymptomatic throughout life and these may represent the smaller pits sometimes described [2]. All the sinuses excised as reported in this paper had been symptomatic and were large requiring an extensive dissection. Any infection was treated and sterilized pre-operatively.

The method of excision described gives good cosmetic results with an incision planned to excise the cutaneous sinus orifice but is otherwise similar to that used for rhytidectomy although it is not usually necessary to extend the incision below the lobule of the ear. The great advantage of the procedure described is the excellent exposure obtained. The key to the dissection is the cephalic approach to the sinus permitting dissection on deep and superficial surfaces of the sinus both anterior and posterior to the pinna, thus demonstrating the sinus and the sinus tracts radiating from the sinus. The reported incidence of recurrence occurring after resecting pre-auricular sinuses is high [ 12,13,15,16] and probably results from using a limited pre-auricular incision which does not extend sufficiently into the temporal region to permit demonstration of the superior border of the sinus with its uppermost anterior and posterior tracts from above. In consequence either the anterior or posterior border of the sinus sac is first dissected free and a number of sinus tracts will be divided from the main body of the sinus before the deep surface of the sinus is exposed thus leaving sinus remnants in situ which give rise to recurrence as had occurred in Case 3 reported in this paper.

It is felt that the technique of methylene blue injection [9] to demonstrate the anatomy of the sinus to be resected may be satisfactory for an uncomplicated sinus, but once infection has occurred it is likely that adhesions will develop and filling of the sinus may then be incomplete. For this reason it is felt to be an unreliable technique to ensure total excision of a pre-auricular sinus. Whilst performing the operative technique described in this paper it has not been necessary to use the

operating microscope, although if, in the sites previously described, proximity of the

facial nerve is feared use of the operating microscope may be helpful.

Wide skin excision followed by grafting or healing by secondary intention has sometimes been necessary in the treatment of recurrent pre-auricular sinuses [ 161 as

has the use of sclerosing material [5]. It is felt that the approach described in this

paper will obviate the necessity for such techniques. The primary pathology of a pre-auricular sinus lies in a subcutaneous plane and an extensive subcutaneous

dissection is facilitated by this approach. Furthermore, if skin excision is necessary

primary closure of the wound may be obtained as in rhytidectomy.

Acknowledgments

I am indebted to Mr. Robert Pracey, with whom this technique was developed at the Royal National Throat Nose and Ear Hospital, for permitting me to report on his patients. I am also grateful to Miss G. Short for her line drawings, to St. Mary’s

Hospital Praed Street, London, W.2. for photographic prints and to Miss Wooding

for typing the manuscript.

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