Facial Danger Zones - Avoiding Nerve Injury in Facial Plastic Surgery

April 1, 2018 | Author: ramarchiori | Category: Lip, Forehead, Anatomical Terms Of Location, Human Head And Neck, Face
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Facial Danger Zones FmiuCPhtic Surgey

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Facial Danger Zones Avoiding Nerve Injury in ~ a c i a~l l h r t i Surgery c

Brooke R. Secliel, M.D. Chairman Department of Plastic and Reconstructive Surgery Lahey Clinic Medical Center Burlington, Massachusetts Assistant Professor of Surgery Harvard Medical School Boston, Massachusetts

ILLUSTRATOR

Anne Beard Greene

Quahty Medical Publishing, Inc. St. Louis, Missouri

1994

Copyrrght O 1994 by Quality Medical Publishing, Inc. All rights reserved. Reproduction of the material herein in any form requires the written permission of the publisher. Printed in the United States of America. PUBLISHER

Karen Berger

PROJECTW A G E R

Carolita Deter

PRODUCTION

Susan Trail

BOOK DEIW

Susan Trail

COYER D ~ I C ~ N Diane M. Beasley

Quality Medical Publishing, Inc. 11970 Borrnan Drive, Suite 222 St. Louis, Missouri 63146 LIBRARY OF CONGRESS CATALOGING-tb-PUBLICKlTONDATA

Seckel, Brooke R. Facial danger zones : avoiding nerve injury in Eacial plastic surgery / Brooke R Seckel ;illustrator, Anne Greene.

p. Un. Indudes bibliographical references and index. ISBN 0-942219-59-7 1.Faceljfc-Complications-Prwention-Atlases. 2. Facial nerveWounds and injurie-Prevention-Atlases. I. Title. RD119.5.F33S43 1994 617.5'20592-dc20

93-39123

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my d e Debbie my daughter Laura and my son Tommy who are my ultimate joy in life

Preface This book is the outgrowth ofan invitation by A Lee Delion, M.D., to partidpak in a panel discussion entided ?Don't h e Your Nerve" held at athe 1992 Annual Scientific Meeting of the American Society of

Plastic and Reco~~~mcdve Surgeons in Washinpn, D.C. I was asked to speak on nerve injuries in aesthetic plastic surgery. A review of the literam sdmulad fkther interat and ultimately led to cadaver dissectiom in the hbramry and exploration in the operating xocrm in preparation for the panel. I b e p to review not only nave injuries but aIso the anatomic loations of the most mceptible n m regions and analyx dissection techniques to avoid injuries. Because I b e bard certification in neurology as well as plastic s-xy, it is not u n d that 1 am asked to*evaluatepatients by my plastic surgery colleagues when facial nerve injury accm in h e course ofrhfidecm y surgery. I had not seen such a facial nerve i n j q ptient for some time when, w i d i n the span of 1 month, I was asked to consult on three patients who had suffered ficial m e injury during rhytideaomy. Fortunately, d-iefirst patient had a neuropraxic marginal mandibular injury; however, the next two patients had buccd and qgu-

matic branch injuries, the first two injuries of

this type I had ever seen following rhytidectomy. Interestingly, both-of patients offered the information that they had had "composite" face lifts.When I spoke with

their surgeons, it became apparent that both had performed extensive midface correction using sub-submuscular aponeurotic system dissection in the cheek area. These latter two cases, followed by telephone consultation on a third similar case, suggested that perhaps the newer, more extended fice-lift techniques were resulting in more facial newe injuries. This convinced me that this subject should be brought to the attention of a wider audience. I therefore approached Karen Berger with the idea of publishing a small atlas on what I term "facial danger zones." I have organized the book by arbitrarily assigning numbers in the order in which I enter the various danger zones in the course of face-Mi surgery; that is to say, the first danger zone I see during dissec~onis danger zone one followed by two, three, four, five, six, and seven.

Out of respect for the privacy of the patients and their referring physicians, I decided against using photographs of patients with

Preface

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facial nerve injuries. Anne Greene's drawings depict the clinical findings in such detail that one can easily diagnose a dinical injury from the illustrations reproduced in the book. Finally, major advances in the surgical techniques for facid aging have occurred in the past 10 years, especially with the recent evolution of techniques to correct midface aging. Such improvements, however, come at the expense of safety in my opinion. Although optimal results are desirable, these

newer advanced techniques require that

particular attention be paid to the peripheral nerve anatomy of the face. We as plastic surgeons must, as always, keep our patient's safety as our first and foremost consideration. Careful attention to the facial danger zones will serve all those who perform the newer techniques and particularly the residents and young plastic surgeons who wiU extend and improve on these observations. Emoh R GchI, X D .

As all who write are keenly aware, the publishing of a book is possible only with the help of many people. The fact that the author's name appears on the cover of the book in no way implies entire responsibility for its contents. Such is the case with this book, for many people have worked hard to bring it to fruition. For the past 12 years Anne Beard Greene has translated my thoughts and words into pictures. Her superb artistic contribution represents a major portion ofthis book. Not only is Anne a skilled medical artist, she is also a learned anatomist and neuroscientist who carefully and fastidiously researches her drawings. She is not content to accept my word as to the location of a nerve or vessel, but she insists on viewing the disseaion and checking the literature herself. Time and again Anne has been an invaluable colleague in all of my publishing efforts. I owe a great debt to my predecessors on the surgical s t a f f of the Lahey Clinic who have set the high standards that challenge all of us who are fortunate enough m practice surgery here. Their legacy includes the superb editorial, medical photography, and medical art departments under the direction of Polly Zarolow, Rich Chevalier, and Jim

MiLlerick, respectively. These departments are a major cornerstone on which the reputation of Lahey Clinic is built. I gratefully acknowledge the permission of Lahey Clinic to use the copyrighted artwork in this volume. I am truly blessed to have a warm, caring, and competent staff. Without: them, I could not possibly maintain a busy practice and residency &g program in addition to performing research and writing. My research and training coordinator, Christine Antonellis, has spent innumerable hours helping me write and rewrite, always with enthusiasm and a bright smile. My secretary, Kerry Duprez; physician assistant, Lorim Herrick; nurse, Lori Watson; assistant, Sloan Shaunessy; and administrator, Christine White, keep my practice running smoothly and provide skillful and supportive patient care. Dimitria ChakaIisj my former scrub nurse and currently the director of our plastic surgery research laboratory, handles much of the administrative and technical details in running our research program. My very competent:and able surgical assistant, Lisa Pappalardo, ensures that: operations run smoothly. Without the expert assistance of these people, time would not permit other interests such as writing. My residents,

Dr. Patricia Eby and Dr. Bill Holmes, have been of immeasurable help in performing cadaver dissections to clarify many of the anatomic points discussed in this book. I a m indebted and feel most fortunate to have the assistance of these professionals. Karen Berger and the staff at Quality Medical Publishing, pardcularIy Carolita Deter, Susan Trail, Cindy Lia, Mary Stueck, Linda Kocher, and Diane Beasley, have

brought this book to publication in a most expeditious fashion and have been delightful to work with. I am most impressed by their competence, professionalism, and high standards.

Obviously, without the love and supprt of my wife Debbie and children Laura and Tommy, I would not have had the energy, enthusiasm, and peace of mind to devote myself fully to this project.

Contents Introduction ........................................................... 1 Facial Danger Zone 1 ................................................ - 4

2 ....................................... .........12 3 ...............................................

18

7 ...............................................

44

Condusion ................................................................

48

References ...............................................................

49

ndex ......................................................................... 51

With today's more aggressive and deeper facial dissection in h e course of face-lift surgery,'-" the peripheral nerves of the face are more often exposed, lie doser to the plane of dissection, and in my opinion are more likely to be injured. Injury to one of the major facial nerve branches creates a catastrophic an$ occasionally irreversible facial deformity. Even patients who do recover muscle function following injury are often left with permanent i n v o l u n q muscle twitching or distortion of the facies by contractwe and shortening of partially denervated muscles. Additionally, interruption of one of the major sensory nerves in the face can result in permanent disability secondary to numbness or, worse, intractable dysesthesia and pain. Thus a keen and thorough understanding of the location of these nerves is of paramount importance if injury is to be avoided.

Introductw n

Facial Danger Zone

continued

I have arbitrarily divided the face into seven facial danger zones based on known anatomic locations of the branches of the peripheral nerves of the face and the sites where they are most susceptible to injury in the course of facial dissection (Figs. A and B). Each of these facial danger zones will be discussed individually with regard to the nerve and consequence of injury, the anatomic borders of the facial danger zone, and the techniques for safe surgical dissection. Although the branching patterns of the nerves, particularly of the facial nerve, may vary from individual to indrvidual, only the most common patterns are shown in this text; the boundaries of the danger zones include these variations. Relationship

Sign of Zonal Injury

Laation

Nerve

to SMAS

6.5 un below external auditory

Great auricular

Posterior to

Numbness of inferior two thirds of ear and adjacent cheek and neck

Temporal branch of facial

Beneath

Paralysis of forehead

Midmandble 2 cm posterior to oral commissure

Marginal mandbular branch of facial

Beneath

Paralysis of lower lip

Triangle formed by connecting dots on malar eminence, posk-

Zygomatic and

Beneath

Paralysis of upper lip and cheek

rior border of mandibular angle, and oral cornmissure

facial

Superior orbital rim above midpupil

Supraorbital and suprandear

Anterior to

Numbness of forehead, upper eyelid, nasal dorsum, scalp

1an below inferior orbital rim below midpupil

lnfraorbitd

Anterior to

Numbness of side of upper nose, cheek, upper lip, lower eyelid

Midmandible below second premolar

Mmtd

Anterior M

Numbness of half of lower lip and chin

canal

Below a line drawn from 0.5 cm below m a p to 2 cm above lateral eyebrow and above

zYgoma

SMAS = submuscular aponeurotic system.

buccal branches of

F&*a External topographic outlines of rhe seven facial danger zones.

Underlying nerves running through each facial danger zone after the slun and SMAS layer have beea removed.

IS, Newe and

Consequence of Injury

1 includes the area in which the great auricular nerve emerges from beneath the sternocleidomastoid muscle, becomes more superficial, and is thus most susceptible to injury. Permanent injury to this nerve results in numbness of or,in the case of a neuroma, painfuI dysesthesia of the lower two thirds of the ear and adjacent neck and cheek skin (Fig. 1A). Another unusual but troublesome syndrome is that caused by compression of the nerve by a nonabsorbable suture used to plicate the platysma-SMAS to the mastoid fascia. This can result in painfuI dysesthesia of the ear, which can be induced by tapping the nerve at the point of compression.

Facial danger zone 1 injury. Shaded areas represent sensory loss or dysesthesia following injury to the great auricular nerve.

Anatomic Location

Facial danger zone 1 (Fig. 1B) is best located by first identifying the point described by McICinney and ICatrana.I4 The patient's head is turned to the opposite side, the stemodeidomastoid muscle is palpated, and a straight line is dropped from the caudal edge of the external auditory canal to a point 6.5 cm below on the midpoint of the muscle belly. I arbitrarily define zone 1 as the area described by a circle with a radius of 3 cm drawn around this point that includes the point of emergence of the great auricular nerve from beneath the sternocleidomastoid muscle at 9 cm below the external auditory canal (Fig. 1C). The lesser occipital nerve emerges higher and stays dong the posterior edge of the muscle belly.

Facial danger zone 1 is centered around a point in the middle ofthe sternocleidomastoid musde M y 6.5 an below the mudal edge of the external auditorv canal.

n radius of 3 cm is wed to include the point ofemergence of the nerve from benmth the sternodeidomasmid muscle, whlch is found 9 un below the exremal auditory canal.

Surgical Dissection

After the postauricular incision is made, it is helpfill to begin the dissection superficially, just deep to the subcutaneous fat, which is thin and superficial to the deep cervical fascia and the sternocleidomastoid muscle. The nerve is posterior to and superficial to the platysmaSMAS at this point (Fig. 1D).When the ear Iobule is pulled forward, one or two tiny postauricular branches of the great auricular nerve can often be seen (Fig. 1E). Identification of these branches helps establish the proper plane for dissection inferiorly over the deep cervical fascia and the sternocleidomastoid muscle.

Temporal Ban& nf racl-r Y ,

.'

Note that the great auricular nerve is posterior to and not protected by the platysrna-SMAS layer through most of its course.

Postauricular Branches of Great Auricular N.

'

External Jugular U

/

Stsrnocleldomaatold M.

I

During dissection, pdmg on the ear lobule anteriorly reveals small terminal p ~ u r i c d a branches r of the great auricular nerve and provides an important due to the proper plane of &ssection in this area.

Suyicd%section continued

Another useful anatomic relationship is the external jugular vein and the great auricular nerve. When the neck flap is dissected off the sternocleidomastoid and platysma muscles, the location of the external jugular vein is observed by first noting its location on the skin surface and watching for a blue shadow anterior to the sternocleidomastoid muscle beneath the skin flap. The great auricular nerve will be 0.5 to 1 cm pos~eriorto the vein at the point where the vein comes into view during dissection (see Fig. 1E). When the pIatysrna-SMAS layer is plicated or suz-ured to the mastoid fascia, the newe should not be compressed by the suture. Rather the platysma-SMAS must cover and protect: the nerve (Fig. IF). Direct contact between suture and nerve can create a painful compressive neuropathy of the great auricular newe . Hamra11J2does not include plication sutures behind the ear lobule in his composite rhytldectomy technique. He tightens the platysma-SMAS in the cheek anterior to the nerve and by excision and repair of the platysma bands. Thus, if his technique is followed meticulously, there should be no risk of compression of the great auricular nerve by suture plication (Fig. 1G).

F-• 1F When the platysma-SMAS layer is plicated to the mastoid fascia behind the ear, it must be folded over the nerve and the suture must not \ touch or compress the nerve.

Fb. 1s When the platysrna-SMAS is plicated in the chgek and anterior neck, elirmnating the need for posterior plication over the mastoid area, a possible compmsive n w ropathy of the great auricular nerve is avoided.

Facial Danger Zone 2 B e Neme

and Consequence of Injuy

Facial danger zone 2 includes the area where the temporal branch of the facial nerve runs under the ternporoparietd fascia-SMAS Iayer>15 having emerged from beneath the parotid gland at the level of the zygoma on its way to innervate the frontalis muscle in the forehead. Injury to the temporal branch results in paralysis of the frontalis muscle. Typically, orbidaris oculi function is spared following temporal branch injury as the muscle receives dual innervation in the form of a second nerve supply coming from the zygomatic branches inferiorly. Clinically, the involved side of the forehead becomes paralyzed, with resultant ptosis of the brow, asymmetry of the eyebrows, and an asymmetric lack of animation on that side of the forehead (Fig. 2A).

Zone 2

Temporal Branch ol Faci I N.

P

Facial danger zone 2 injury. The right temporal branch of the facial nerve is damaged, resulting in paralysis of the right frontah muscle that creates a characteristic facies with unilateral brow ptosis and asymmetric lack of animation of the involved side of the forehead.

Facid danger zone 2 is best localized by drawing a line from a point 0.5 an below the t r a p to a point 2 cm above the lateral eyebrow.16,17 A second line is drawn along the zygoma to the lateral orbital rim. A third line is then dropped from the point above the eyebrow through the lateral end of the eyebrow to the zygoma. These three lines define a triangle (Figs. 2B and 2C) in which the temporal branch ofthe facial nerve lies on the undersurface of the temporoparietai fascia-SMAS layer and is more likely to be injured.

Facial danger zone 2 is outlined by drawing a h e 0.5 m below the t r a p to a point 2 crn above the lateral eyebrow, drawing a second line on the zygoma to the lateral orbital rim, and connecting these two lines with a third line.

F&. 2C Course of the temporal branch of the facial nerve above the zygoma.

The temporal branch of the facial nerve emerges from beneath the parotid gland to run on the undersurface of the temporoparietal fascia-SMAS layer. Thus dissection may be carried out deep to the temporoparieta1 fascia-SMAS layer or judiciously subcutaneously above his layer but not immediately beneath the ternporoparietal fascia-SMAS layer. Safe dissection in facial danger zone 2 requires that the surgeon develop a ccmesotemporalis,"as described by Marino.18 This plane is developed by dissecting the subtemporoparietal fascia-SMAS layer from the scalp toward the supraorbital rim down to the level of the zygoma and hssecting the supra-SMAS layer subcutaneously in the cheek from the mandibular ramus up to the zygoma (Fig. 2D). The point at which these two planes meet reveals the SMAS layer, or mesotemporalis, in which the temporal branch of the facial nerve resides and this branch can, on occasion, be seen running just inferior to the frontal branch of the superficial tempord artery. Exposure and identification of the mesotemporalis will help avoid injury to this nerve. In subperiosteal rhytidectomy or other procedures in which tissues are to be elevated from their attachment to the zygoma, the superficial layer of the deep temporal fascia can be incised to enter the superficial temporal fat pad within this space, and dissection can proceed inferiorly and anteriorly with less chance of injuring the frontal b r a n ~ h ~(Fig. y ~ ~2E). ~

&

Surgical exposure of the mesotemporalls conraining the temporal branch of the facial nerve during the course of rhytidectomy and coronal brow lift. The scissors are deep to the superficial layer of the deep temporal fascia, a safe plane for anterior dissection beneath the temporal branch. The supeficial temporal fat pad is a useful landmark in determining the proper

plant.9

LOO^^ Arsolar Tisaus

'smporo-parietal Famcla (SM~S) ssp Temporal Fascia: Supsrficlal Lever ~tmp Layer rontal Branch 01 Supsrficisl Temporal A

ramporal Branch of Facial N.

I

-2ygomatic

Arch

Cross section through facial danger zone 2 showing the temporal branch of the facial nerve and the frontal branches of the superficial ternpod artery on the undersurface of the ternproparid fmiaSMAS layer. Note the superficial temporal fat pad beneath the superficial layer of the deep temporal fascia. Thls plane can be dissected to elevate the SMAS off the zygoma without injuring the tmnp0rd branch of the faaal nerve.

Facia6 Dander Zone 3 17ie Neme and Consequence of Injury

Facial danger zone 3 includes the marginal mandibular branch of the facial nerve at a point in its course where it is most vulnerable anteriorly as the platysrnaSMAS layer thins and the nerve courses superiorly to innervate the depressor [email protected] oris rnu~cle.~~J~ Injury to this nerve creates a noticeable and extremely distressing deformity, especially when the patient smiles. During grimacing the denervated depressor an& oris muscle cannot pull the corner of the mouth and lower lip down, resdting in an inability to show the lower teeth on the affected side (Flg. 3A). At rest the tone in the normally innervated zygomaticus muscles is unopposed because the denervated depressor angdi oris muscle lacks tone, and the corner of the mouth is p d e d up so that at rest the lower lip rides high over the teeth in a unilateral "pout. "

rMarginal

Zone 3

/

Mandibular Branch of Faclal N.

This patient, who has a right marginal mandibular branch injury, is grimacing in an attempt to show the lower teeth. The right lower lip rides up over the lower teeth and cannot be pulled down. Be certain the patient is not contracting the plarysma muscle, whch in some cases assists the depressor an& oris musde in pulling the lip inferiorly.

anatomic Location

Facial danger zone 3 is best described by drawing a point on the middle of the mandibular body 2 cm posterior to the oral cornrnissure and drawing a circle with a radius of 2 crn around this pointz1J2(Fig. 3B). This process defines a circular area, facial danger zone 3, in which the platysma-SMAS thins, exposing the marginal mandibular branch to injury. The anterior facial artery and vein also cross this zone and are susceptible to injury (Fig. 3C).

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