University of Toronto Medical Journal, February 1991

56 Pages·1991·6.8 MB·English

by  Medical Society of the University of Toronto

Yin today’s highly competitive pharmaceutical
industry, Novopharm is committed to the
production of high quality pharmaceuticals.
Highly skilled and dedicated professionals utilize
the latest scientific technology to develop and
manufacture the high quality products which are
representative of Novopharm’s standard of
excellence.
We never compromise when it comes to our guiding
nciple... quality above all.
That’s one reason why more prescriptions are filled
with the Novopharm brand than any other brand in
Canada.
\ ■
Q novopharm ltd.
1290 Ellesmere Road, Scarborough, Ontario M1P 2Y1
[phone]
Number One in Canada in
Prescriptions Dispensed*
PAAB
CCPP
‘Data on file.
University of Toronto
MEDICAL JOURNAL
Established in 1923, An Undergraduate Publication Volume 68 - N92, February 1991
Table of Contents
7 PLASTIC SURGERY
Facial Reanimation: The Surgical Management of Facial Palsy
Ariel A. Watitman, 9T2., Ronald M. Zuker, M.D.. F.R.C.S. (C),
F.A.C.S.
14 BASIC SCIENCE
The Role of Oncogenes in Determining Primary Radioresistance
and Secondary Metastatic Spread
R.G. Bristow. MSc.. 9T2. F.S. Pardo. M.D., M.A., S.D. Young,
Ph. D„ 9T3, R.P. Hill. Ph. D.
P. 22 22 FEATURE ARTICLE
Functional Neuroimaging: Technetium 99m Hf.yamethyl-
Propyleneamine Oxime and Single Photon Emission Computed
Tomography in the Differential Diagnosis of Dementia
Dae-Gyun Chung, 9T2, Masanori Ichise, M.D., F.R.C.P. (C)
28 ONCOLOGY
Bone Metastasis: Radiotherapy for Effective Palliation of Pain
Christopher C. Leighton, 9T2, Colvin D. Springer. M.B.,
F.R.C.P. (C)
32 ORTHOPAEDIC SURGERY
The Principles of Osteochondral Allografts
Mohammed N. Mahomed , 9T2
cdcAgg^
37 BIOMEDICAL ETHICS
P. 32
Euthanasia: On Intending Death
Andrew Pierre, 9T3
41 NEWS AND VIEWS
The 1990 Gairdner Foundation International Awards
Paul Ellis. M.Sc., 9T2, JoAnn Majerovich, 9T2, Lily Angelov,
9T2
45 IMPRESSIONS
Ophthalmology in India
Richard Hudson Johnston, 9T2
Lookout Within Our Borders
Jean Chamberlain, 9T1
48 QUICK DIAGNOSIS
Elisabeth Van-Bussel, B.Sc., 9T2, Anna Day, M.D., F.R.C.P. (C)
52 BOOK REVIEWS
P.37
Volume 68 - N2 2, February 1991 3
Editorial Editorial Staff
Mark Bradley Noss
Shanthi Vasudevan Editors-in-Chief
Mark Bradley Noss, M.Sc., 9T2
Shanthi Vasudevan, Ph.D., 9T2
The first issue of this year's University of Toronto
Associate Editors
Medical Journal was well received. The articles were of
outstanding quality and we welcome articles for future Mohammed N. Mahomed, 9T2
issues in the fields of Basic Science, Clinical Medicine, Corinne Fischer, 9T3
Community Health or any other field of common inter¬
Book Reviews Editor
est to medical students, practioners and the general
Bjug Borgundvaag, Ph.D., 9T2
readership .
Quick Diagnosis Editor
We would like to express our gratitude to Dr. Marvin
Alan Barolet, 9T2
Auerbach who has established an award on behalf of his
brother, the Late Dr. Berney Auerbach, a former editor News and Views
of the U of T Medical Journal. We wish to thank him for
Paul Ellis, M.Sc., 9T2
his generosity and support.
Editorial Board
Despite the inclement weather, the benefit concert
Paul E. Bemick, B.Sc., 9T2
was a success. We are very gratetul to Mrs.
Nicoletta Bonafede B.Sc., 9T2
Ranganathan, Dept, of Music, Queen's University, Dr.
Ronny Kafiluddi, B.Sc., D.R.S., Ph.D., 9T3
Kallury Rao, Dept, of Chemistry, University of Toronto
Ubendranauth Kalicharren, B.Sc., 9T3
and Meera Krishnan for their splendid performance. We
Joel A. Kirsh, B.A.Sc., M.Sc., 9T2
would also like to thank all those people who donated
Mitesh Mehta, 9T1
their time and money for such a worthy cause.
Amita Patnaik 9T2
Owen Prowse, 9T4
This issue features articles which will be of interest to
Nicola Richmond, 9T2
our diverse readership. The feature article on functional
Line Vautour, 9T2
neuroimaging describes advances in SPECT imaging.
This new imaging technique demonstrates tremendous Secretary
potential in the diagnosis of dementia. This issue also
Mrs. Audrey Randall
includes articles on the role of oncogenes in the
Treasurer
radioresistence of primary tumours, the effects of radio-
therapy in relieving pain caused by bone metastasis, the Cheryl Jaigobin, 9T2
principles of osteochondral allografts and facial reani-
Advertising Director
mation. Also published in this issue is the runner-up
Bjug Borgundvaag, Ph.D., 9T2
essay of the first annual Biomedical Ethics Essay Com-
petition. This article addresses the issue of euthanasia. Art Director
We are proud to include coverage of the 1990 Gairdner
Rick Kogucki, B.Sc., B.Sc. B.M.C., 9T1
Awards. We feel that this adds a new dimension to the
Biomedical Communications
Journal. The Quick Diagnosis features rapid interpre-
tation of arterial blood gases and pulmonary function Dianne Drummond, B.A., B.Sc. B.M.C., 9T2
tests. Marc Gosselin, B.Sc. B.M.C., 9T2
Chantal Lichaa, B.A., B.Sc. B.M.C., 9T2
Again, we wish to remind our readers that several
Luba Magdenko, B.A., B.Sc. B.M.C., 9T2
prizes are available for the best articles published.
Gino Maulucci, B.Sc., B.Sc. B.M.C., 9T2
Please see inside for details.
Heather Milne, B.Sc. B.M.C., 9T2
Cynthia Stolovitz, M.D., B.Sc. B.M.C., 9T2
Finally, we would appreciate feedback from our
Nicholas Woolridge, B.F.A., B.Sc.B.M.C., 9T2
readers. Please send us your comments, thoughts and/or
Faculty Consulting Advisor
impressions for our ‘Letters to the Editor’ section.
Dr. Catherine G. Chalin
4 University of Toronto Medical Journal
Patrons
The .Journal Staff and the Medical Society wish to thank the following patrons for their generous support:
Dr. Susan Abbey Dr. Stanley Fenton Dr. Peter Lee Dr. Kenneth Reed
Dr. Sharon M. Abel Dr. J. Fleming Dr. Lawrence Leiter Dr. Robert N. Richards
Dr. Arnold Aberman Dr. R. Fleming Dr. Nicholas Leyland Dr. Robin Richards
Dr. Paul Adam Dr. I. Fettes Dr. Samuel Librach Dr. Kenneth Robb
Mrs. E.J. Akesson Dr. Frank J. Foley Dr. Samuel V. Lichtenstein Dr. Fred Rosen
Dr. Peter W. Alberti Dr. Michael Ford Dr. H. Lavina Lickley Dr. Irving Rosen
Dr. Gerald J. Alexander Dr. W.C.F. Forder Mr. Sidney Liswood Dr. Irving E. Rosen
Dr. E.C. Allen Dr. Rodney Fowler Dr. H. Little Dr. John Ross
Dr. Douglas Alton Dr. W.H. Francombe Dr. Walter M. Little Dr. Lome E. Rotstein
Dr. Dominick Amato Dr. Arnis Freiberg Dr. Lynn Loach Dr. Cheryl Rowe
Dr. Aubie Angel Dr. Norman E. Fremes Dr. Konstantin R. Loewig Dr. R.L. Ruderman
Dr. Crawford Anglin Dr. Gorden Froggatt Dr. Donald Low Dr. Peter Runmey
Dr. Sylvia Asa Dr. A. E. M. Geisler Dr. Mark Lowrey Dr. Fred Saibil
Dr. Mary Jane Ashley Drs. Richard & Joan Gladstone Dr. Frederick Lowy Dr. Tomas A. Salerno
Mr. W. A. Backley Dr. Wilton R. Glenney Dr. John Lundon Dr. Irving Salit
Dr. Michael Baida Dr. David Goldberg Dr. Allan Luxton Dr. Robert B. Salter
Dr Michael A. Baker Dr. Melvyn Goldberg Dr. Ross Mackay Dr. Mahender Sarin
Dr. B. Balshin Dr. Michael R. Goldberg Dr. Susan Mackinnon Dr. Thomas Shaw-Stiffel
Dr. Eric J. Barker Dr. Barry Goldlist Dr. J. L. Madigan Dr. Neil Shear
Dr. Jack Barkin Dr. Irvin Gollish Dr. Aaron Malkin Dr. Michael Shier
Dr. Marshall Barkin Dr. M.K. Gospodarowicz Dr. Dina Gorden Malkin Dr. Jerry Shime
Dr. Colin Bayliss Dr. Robin Gray Dr. Dina Gordon Malkin Dr. Barry H. Shrott
Dr. Lindsay A. Belch Dr. Paul Greig Dr. Constantine Mallin Dr. Jack Shuber
Dr. Susan Belo Dr. David Greyson Dr. O. J. Mandel Dr. K. H Shumak
Dr. Sam Berger Dr. Allan E. Gross Dr. Jaanus Marley Dr. Brian N. Silver
Dr. John A. Beswick Dr. Michael L. Guinness Dr. Joseph Marotta Dr. Malcolm Silver
Dr. H. Birman Dr. Abraham L. Halpem Dr. Ana Marquez-Julio Dr. Bernard Silverman
Dr. Sonia D. Bot Dr. Arthur Ham Dr. A. Bruce Marshall Dr. Louis Siminovitch
Dr. L. Boxall Dr. Mary Hannah Dr. Ray Martin Dr. Carlton G. Smith
Dr. J. L. Brayley Dr. Walter J. Hannah Dr. B. Massouda Dr. J. Donald Smith
Dr. Irvin Broder The Hannah Institute Dr. R.C. Mavjee Dr. G. Snell
Dr. Charles B. Brown Dr. Gordon D. Hardacre Dr. Steven McCabe Dr. Kenneth W. Sniderman
Dr. P.J. Brueckner Dr. Ian Harrington Dr. Nancy McKee Dr. Glasier Somerville
Dr. Martin Buckspan Dr. John Hart Dr. James B J. Mckendry Dr. P. A. Spear
Dr. Patricia Burrows Dr. Bart Harvey Dr. David Mcneely Dr. Russell Springate
Dr. Brian Butler Dr. Robert Haslam Dr. D. T. Mcneely Dr. John C. Stears
Dr. David S. Byers Dr. Elizabeth Heathcote Dr. Rosemary Meier Dr. Donald A. Stewart
Dr. Doreen Campbell Dr. Roberte Hegele Dr. Charles Merrill Dr. Margaret Stoicheff
Dr. Lorie Cappe Dr. Murray Herst Dr. Peter Mingie Dr. Robert Stone
Dr. A. Cecutti Dr. R. C. Hicks Dr. Kenneth Money Dr. & Mrs. I. Strashin
Dr. Abraham Chaiton Dr. Robert Hilliard Dr. K. Moore Dr. Albert C. Strickler
Dr. Catherine G. Chalin Dr. Sophie Hafstader Dr. Brian Morris Dr. Charles Tator
Dr. Israel Chambi Dr. Richard Holloway Dr. Heather Morris Dr. John Taylor
Dr. Morris Charendoff Dr. Richard Holtby Dr. Rebeka Moscarello Dr. Ron Taylor
Dr. Pamela Chart Dr. Stephen Holzapfe! MSH-OTL Associates Dr. Marvin Tile
Dr. Davy Cheng Dr. W. J Horsey Dr. Paul J. Muller Dr. George X. Trimble
Dr. Albert Cheske Dr. Robert Howard Dr. James F. Murray Dr. Graham Trope
Dr. Yuet Cheung Dr. Michael Howcroft Dr. Salim Naqvi Dr. William S. Tucker
Mrs. Mary Chipman Dr. Shao-Nan Huang Dr. John Nazareth Prof. Gerald Turner
Dr. A. F. Colantonio Dr. Alan Hudson Dr. Hugh R C. Norman Dr. David Uden
Connaught Laboratories Limited Dr. Robin Humphreys Obstetrics & Gynaecology Dept., Dr. Lome Umemoto
Dr. John Connolly Dr. Gordon Hunter St. Michael’s Hospital Dr. Martin G. Unger
Dr. J.J. Connon Dr. M. Hutcheon Dr. Richard Ogilvie Dr. Gerald Llrbach
Dr. S.J. Coombs Dr. R.H. Hyland Dr. Dimitrios Oreopoulos Dr. Joan M. Vale
Dr. Donald Cowan Dr. F. de la Iglesia Otolaryngology Assoc., TGH Dr. Marica Varga
Dr. William Crysdale Dr. M. Ip Dr. David Ouchterlony Dr. Hillar Vellend
Dr. Donald Currie Dr. Robert W. Jackson Dr. Howard J. Ovens Dr. Paul Walfish
Dr. Iyabo 0. Daramola Dr. D. G. Jagdeo Dr. Titus Owolabi Dr. Christopher Wallace
Dr. Derek A. Davidson Dr. Christopher Jamieson Dr. Harry Palter Dr. Gary Webb
Dr. Mervyn Deitel Dr. D. Anna Jarvis Dr. Fred Papsin Dr. Robert K. Weber
Dr. G.O. De villa Dr. Michael Jewett Dr. H. Pasternak Dr. Peter Webster
Dr. H. Roslyn Devlin Dr. Maridene Johnston Dr. Robert Patten Dr. Victor Weinberg
Dr. S. P. Dhiman Dr. Donald Jones Dr. Alexander Patterson Dr. Solomon Weinstock
Dr. Bernard Dickens Dr. Albin T. Jousse Dr. Thomas A. Patterson Dr. Richard D. Weisel
Dr. John Dirks Dr. Alexander Kennedy Dr. Gordon A. Pengelly Dr. Sheila Weitzman
Dr. Robert Disenhouse Dr. Donald W. Killinger Dr. A. C. Percheson Dr. Catharine Whiteside
Dr. Sarma Dittakavi Dr. Max Kleinman Dr. Richard G. Perrin Dr. E. Douglas Wigle
Divisions of O.T. and P.T. Dr. Amira Klip Dr. Mel Petersiel Dr. Robert Wilkinson
Dr. Sheila K. Doyle Dr. Irvine A. Korman Dr. Anne M. Phillips Dr. D.R Wilson
Dr. James Dubbin Dr. Colin Kovacs Dr. D.G. Pond Dr. Jonathan Wilson
Dr. James Duffin Dr. Stephen Kraft Dr. Peter Y. Poon Ms. Dorothy Wylie
Dr. Stuart Z. Dyment Dr. V. Kurdyak Dr. Annette Poon-Toye Dr. Dennis Xuereb
Dr. Gerald Edelist Dr. Richard Lamon Dr. Jeffrey Posnick Dr. James Yao
Dr. John F. Edmonds Dr. Bernard Langer Dr. Kathleen Pritchard Dr. Douglas E. Yates
Dr. Michael England Dr. Edward Lansdown Dr. Kenneth Prit/ker Dr. Shery Zener
Family and Community Medicine, SHC Dr. Catherine Y. Lau Dr. John Provan Dr. Maria Zorzitto
Dr. Stan Feinberg Mr. Joseph Lavoie Dr. Ian Quirt Dr Ronald Zuker
Dr. Ronald Fenton Dr. D. Lawee Dr. Anita Rachlis
Volume 68 - Ng 2, February 1991 5
University of Toronto
MEDICAL JOURNAL
Room 2141, Medical Sciences Building, Toronto, Canada, M5S 1A8 [phone]
Dear Reader,
Thank you for responding to our letter in the first issue. New information
has come to light to help us understand that we did not qualify for a Federal
Sales Tax Exemption. Therefore, we need to raise approximately $8,000.00 to
pay outstanding taxes. We apologize for any misunderstanding generated by
our first letter, but the problem remains just as crucial for the Journal.
In order for the Medical Journal to survive, your monetary assistance is
urgently requested. Any financial assistance on your part would be greatly
appreciated. Thanking you in advance, we remain
Respectfully yours
/^7—--
Shanthi Vasudevan and Mark Bradley Noss
Editors-in-Chief
6 University of Toronto Medical Journal
Plastic Surgery
Facial Reanimation: The Surgical Management of Facial Palsy
ARIEL A. WAITZMAN, 9T2 and RONALD M. ZUKER, M.D., F.R.C.S.(C)., F.A.C.S.*
*Associate Professor, Department of Surgery, University of Toronto; Head, Division of Plastic Surgery,
The Hospital for Sick Children, Toronto, Canada.
ABSTRACT ABSTRAIT
Patients with facial paralysis may present with a variety of Des patients avec une paralysie faciale peuvent se presenter avec
aesthetic and functional problems. In this review the etiol¬ une variete de problemes esthetiques et fonctionnels. Dans cet
ogy and diagnosis of facial nerve palsy, and indications for article, 1'etiologie et la diagnose d'une paralvsie au nerf facial sont
various treatment methods along with an outline of each discutees. Les indications pour differentes methodes de traite-
ment sont decrites avec un apercu de chaque procedure chirurgi-
surgical procedure are discussed. Emphasis is put upon
cale. L’emphase est mise sur les nouvelles techniques
the newer microneurovascular techniques. The use of free
microneurovasculaires. L’utilisation de transferts de muscles
vascularized muscle transplants allows for facial symme¬
libres et vascularises permet
try at rest, a balanced
une sy metric du visage au re¬
smile, and spontaneous fa¬
pos, un sourire equilibre ainsi
cial expression with emo¬
qu’une expression faciale
tion.
spontanee avec emotion.
INTRODUCTION
and the chorda tympani (sali¬
Paralysis of the facial
vation and taste). The facial
nerve (CN VII) presents a spe¬
nerve exits the skull via the
cial challenge to reconstruc¬
stylomastoid foramen and di¬
tive surgeons. Affected indi¬
vides into its terminal
viduals suffer from both aes¬
branches between the super¬
thetic and functional impair¬
ficial and deep components
ments. Often these deficits
of the parotid gland'-4.
lead to problems in social in¬
teraction, and the develop¬ There are five main termi¬
ment of concurrent psycho¬ nal branches of the facial
logical difficulties1. nerve (temporal, zygomatic,
ANATOMY OF THE buccal, mandibular, and cer¬
FACIAL NERVE vical). When examined by
topical organization, the fa¬
The facial nerve consists of
cial nerve has three main ar¬
3 main components: motor
eas of innervation, each rep¬
supply to the muscles of facial
resented by a separate nerve
expression, visceral efferents
fascicle. Fascicle 1 (perioral)
(parasympathetic) to the sali¬
innervates the orbicularis
vary glands (except the pa¬
oris, fascicle 2 the orbicularis oculi, and fascicle 3 (mimetic) in¬
rotid), and visceral afferents (taste) from the anterior two thirds of
nervates all other muscles of facial expression'. This, however, is
the tongue2. The motor nucleus lies in the lower pons. The axons
an oversimplification of the facial nerve organization. The facial
originating in this nucleus encircle the abducens nucleus and then
exit the brain stem at the lateral aspect of the cerebellopontine nerve has been found to communicate by more than 32 branches
angle. Visceral afferent and efferent fibers terminate and arise in with the 5th, 8th, 9th, and 10th cranial nerves, the otic ganglion,
the nucleus/tractus solitarius and superior salivary nucleus re¬ and sympathetic fibers6.
spectively, and accompany the facial nerve as the nervus
FACIAL PALSY
intermedius. Running adjacent to the vestibulocochlear nerve,
Facial nerve paralysis leads to reduced or absent voluntary and
the facial nerve enters the internal auditory meatus. Some of the
spontaneous facial movements, a lack of resting tone of the facial
parasympathetic fibers enter the greater petrosal nerve to eventu¬
ally innervate the lacrimal gland. The facial nerve then passes muscles, and functional difficulties. These deficits may be accen¬
through the facial canal, branching to form the nerve to stapedius tuated by a relative hyperactivity of the contralateral normal
Volume 68 - NQ 2, February 1991 7
inflammatory-immune disorder, characterized by a viral
notional and aesthetic reconstruction is usually
prodrome causing changes in taste, pain around the ear, and
three regions; the forehead, the eye, and the
numbness in the face and tongue. Sixty percent of patients expe¬
nal problems resulting from lack of tone about the
rience an upper respiratory tract infection or gastroenteritis one to
rneal exposure, leading to irritation, injury and ex-
three weeks before the palsy occurs. A primary disorder of the
c\ ssi\ scai ing. Corneal ulceration and scarring may occur, even¬
sensory fibers causing edema and compression of the motor axons
tual iy leading to blindness. Oral functional difficulties include
in the facial canal is thought to be responsible for the paralysis.
Seventy to 85% of patients with this condition fully recover within
.
Table 11 Etiologies of Facial Paralysis about 4-8 weeks, while approximately 15% go on to severe degen¬
eration". Other lesions of the facial nerve, which usually heal
Congenital Idiopathic (isolated), Moebius syndrome, dys¬ well with minimal permanent deficit, are neurapraxic injuries
trophia myotonica, Bell's Melkersson's syn¬ (nerve compression with temporary interruption of axoplasmic
drome, hemifacial microsomia.
flow), and a cleanly divided nerve which is repaired directly. Of
those patients requiring reconstruction for facial palsy at the Hos¬
Traumatic Basal skull fractures, middle ear injury, facial
pital for Sick Children and Toronto General Hospital, the most
injury, altitude paralysis, forceps delivery,
common etiology was congenital, followed by post traumatic and
molding trauma at birth.
neoplastic. Bell’s palsy and other post infectious lesions were in
the minority7. The incidence of congenital facial palsy is thought
Infectious Otitis externa, otitis media, mumps, mastoid¬
to be 0.9/100013.
itis, chickenpox, herpes zoster oticus, enceph¬
alitis, poliomyelitis, leprosy, mononucleosis, DIAGNOSIS
influenza, malaria, syphilis, sarcoidosis, Cox-
The diagnosis of facial palsy is relatively simple. However, the
sackie virus, Bell's palsy.
resultant facial paralysis is only a symptom, and it is imperative
Metabolic Diabetes mellitus, hyperthyroidism. that the underlying disease process be identified. A proper history
and physical examination are essential. The site of the lesion can
Neurologic Stroke, multiple sclerosis, myasthenia gravis, often be determined by testing the end organs of branches of the
Guillian-Barre syndrome. facial nerve. Alterations in taste, hearing, and salivation are useful
clues, and may be elicited using special tests during the physical
Neoplastic Cholesteatoma, 7th nerve tumor, glomus jugu- exam. If necessary, the lesion can be precisely located using
lare, leukemia, meningioma, teratoma, he¬
electrodiagnostic tests including electromyography and nerve
mangioblastoma, carcinoma, hemanigioma of
conduction studies, tomography, CT scanning, or MRI714. A
eardrum, hydradenoma of external canal, os¬
summary of the different anatomic sites of a lesion, the signs
teopetrosis, schwannoma, sarcoma.
produced, and the differential diagnosis is presented in Table 2411.
Special procedures such as CT or MRI are often warranted to rule
Toxic Thalidomide, tetanus, diphtheria.
out a tumor as the cause of a facial palsy.
Iatrogenic Parotid surgery, mastoid surgery, post tonsil¬ TREATMENT
lectomy and adenoidectomy, mandibular block
Numerous approaches have been developed for the treatment
anaesthesia, intracranial procedures.
of facial paralysis. Techniques for reconstruction may be divided
into static and dynamic procedures. The static procedures may
drooling and pocketing of food in the buccal cavity7 8. Both the achieve symmetry at rest and improve functional deficits. They
aesthetic and functional impairments may vary tremendously in do not, however, promote facial movement, and therefore are
severity and location.
generally used in cases where a rapid functional improvement is
needed, or the rehabilitative potential is low7. Methods such as
The ideal reconstruction of facial paralysis would achieve fa¬
blepharoplasties, tarsorrhaphies, cartilage grafting, and fascia lata
cial symmetry at rest, separate and selective function of the vari¬
slings may be particularly useful for treating a paralytic lower lid
ous muscle groups, spontaneous and appropriate mimetic (facial
ectropion8. For example, in patients with a paralyzed orbicularis
expression) function, no loss of important motor functions (ie.
oculi muscle, the continual pull of gravity draws the atonic lower
from donor sites), and rapid restoration of tone and motion4. Un¬
lid into a progressively sagging position. The patient becomes
fortunately no single procedure can alleviate all the components of
unable to fully close the eye, and the altered tear flow mechanics
a facial palsy, and all present treatment strategies achieve less than
cause accumulation of tears in the middle of the lower lid, which
optimal results10.
then roll onto the cheek8. Static procedures may also be employed
ETIOLOGY OF FACIAL NERVE PALSY
about the mouth. Slings made of synthetic materials like marlex,
As presented in fable I, there are many etiological mecha¬ teflon or dacron, and autogenous materials like fascia lata or
nisms that may cause facial paralysis41112. The most common dermis, may be used to suspend the corner of the commissure of
form of facial paralysis is a Bell’s palsy, with an incidence of 23/ the mouth. Rhytidectomies (facelift procedures) also have some
100,000 per year13. Bell’s palsy is most likely due to a viral- applications in this respect6-7.
8 University of Toronto Medical Journal
Table 2.1 Diagnosis of Facial Paralysis
Level of Lesion Investigations Signs Diagnosis
Supranuclear CNS exam, CT, MRI Good tone, intact upper face, Trauma, CVA
spontaneous smiling,
neurological deficits
Nuclear (Pons) CNS EXAM, CT, MRI 6th & 7th cranial nerves involved, Vascular or neoplastic
corticospinal tract signs POLIOMYELITIS, MULTIPLE
SCLEROSIS, ENCEPHALITIS
Cerebello¬ CNS exam, CT, MRI 5th, 8th, 9th, 1 0th & 11 th cranial Meningioma, neurinoma
pontine ANGLE NERVE INVOLVEMENT, ALTERED CHOLESTEATOMA, FRACTURE,
TASTE, LACRIMATION OR SALIVATION. ARACHNOID CYST
Geniculate ganglion Tear test, CT, MRI Facial paralysis, hyperacusis, Herpes zoster oticus,
ALTERED TASTE, LACRIMATION, OR FRACTURE, CHOLESTEATOMA,
SALIVATION Bell's Palsy, AVM,
neurinoma Meningioma
Tympano¬ Stapedial reflex, taste, Facial paralysis, altered taste or Bell's palsy, fracture,
mastoid SALIVATION SALIVATION, INTACT LACRIMATION CHOLESTEATOMA, INFECTION
Extracranial Facial movement Facial paralysis, intact taste and Trauma, tumor, parotid
SALIVATION, |AW DEVIATION TO NORMAL CARCINOMA, PHARYNGEAL
SIDE CARCINOMA
Dynamic procedures always supersede other treatment op¬ ral supportive structures, muscular atrophy, and the loss of a cer¬
tions if applicable. These techniques range in complexity from tain percentage of central nuclei6.
simple partially dynamic procedures to assist eye closure, such as
surgical implantation of metal springs, gold weights, or magnets If the proximal stump of the facial nerve is not available, a
into the eye lids, to intricate microsurgical approaches816'18. cross-facial nerve graft is indicated. This technique was first
demonstrated by Smith with limited success10. Anderl18 modified
Early direct repair of an interrupted facial nerve is the treat¬
this approach using multiple grafts and a two stage procedure,
ment of choice. Distortion of the neuromuscular architecture and
with better results. In the first stage, sural nerve grafts are
attrition of mimetic muscles are minimized, resulting in an opti¬
anastomosed to branches of the facial nerve on the normal side.
mal outcome6’7,9. If a gap exists between the proximal and distal
The grafts are then tunnelled across the face using small incisions,
ends of the nerve, or if a tensionless repair is not possible, an
and the distal ends are banked on the paralysed side of the face.
interpositional nerve graft should be performed. The first suc¬
cessful facial nerve graft was reported by Bunnell in 192719. Four to six months later, a distal anastomoses is performed to
However, few were attempted until 1950, when trauma victims attach the grafts to the peripheral branches of the paralyzed facial
from World War II and patients undergoing radical resections for nerve18. The peripheral distribution of the donor facial nerve is
parotid gland tumors sparked interest in facial nerve grafting20. important. If properly selected, several small branches of the
The sural nerve is usually used as the donor graft. It is a long donor facial nerve can be sacrificed without disturbing the func¬
nerve with few branches along the major part of its course. Expo¬ tion of the normal side. This is due to the abundant nerve supply
sure and removal of the nerve from the donor site is relatively to the facial muscles and the extensive interfascicular ramifica¬
simple, and the patient experiences minimal functional loss21. tions of the facial nerve, which provides for coverage of the sacri¬
Both intra and extra-cranial grafting are possible, therefore a ficed axons by the remaining branches18. The facial nerve has
wide variety of lesions may be bypassed22. The use of the proxi¬ excellent regeneration potential, although the results of a cross¬
mal segment for axonal input, and the peripheral segment of the facial nerve graft never achieve the quality of an ipsilateral re-
facial nerve for directing the regenerating axons, usually provides jt has been the experience of the senior author and
pair18-23-24.
a good result. Typically some deficits will be present after heal¬ others10, that although it may provide some tone about the eye, a
ing. General weakness, tightness, and slight spasticity, along cross-facial nerve graft alone does not provide enough innerva¬
with decreased coordination, synkinesis, discrepancies in sponta¬ tion power to produce a satisfactory smile. Therefore, to recon¬
neous expression, and some regional atrophy are all possible struct a smile, the cross-facial nerve graft is followed by a free
complications. These deficiencies may be due to reduction or muscle transplant. Other authors have used cross-facial nerve
misdirection of axon growth, effects of scar tissue about the neu¬
grafts as an isolated procedure, and are satisfied with the results18.
Volume 68 - N- 2, February 1991 9
morbidity may be a problem (eg. chewing difficulties)25. The
voluntary movement gained is often inadequate, resulting in an
asymmetrical smile.
FREE MUSCLE TRANSPLANTS
The concept of free muscle grafting for the treatment of facial
paralysis was introduced by Thompson in 197128. Free composite
grafts, which have been selectively denervated two weeks prior,
are used. The grafts are sutured into place on the paralyzed side of
the face. Reinnervation occurs by the process of neurotization
(growth of new axons into the muscle) through intact underlying
muscle. The lack of vascular reanastomosis requires the graft size
to be very small. This greatly limits the value of this procedure,
since the contractile force necessary for facial movement cannot
be obtained28-29.
Advances in microneurovascular surgical techniques have al¬
Figure 1. Free Segmental gracilis transfer with vascular
lowed the development of free vascularized muscle transplants30.
pedicle aligned on patient's face.
These microsurgical procedures are presently considered state of
Nerve transfer procedures have also been described and proven the art for many difficult reconstructive challenges. Free
useful for facial palsies when the facial musculature is adequate. vascularized muscle transplants were first used to replace forearm
Although several cranial nerves have been utilized, the most suc¬ flexors lost either to trauma or Volkmann's ischemic contrac¬
cessful to date is the hypoglossal to facial (CN XII to CN VII) ture30. As techniques developed, applications for footdrop, loss of
transfer, as popularized by Baker and Conley25. Resting tone and forearm and knee extensors, loss of elbow flexors, and facial pa¬
voluntary movement are often adequate, but there can be no spon¬ ralysis were discovered24-28-30 35. The proper choice of a donor
taneous facial expression. Movement of the paralyzed side is usu¬ muscle is imperative. A muscle with the correct amount of viable
ally present 4-6 months after the procedure, but the patient must be bulk for the force of contraction needed, and the proper fiber
retrained to push their tongue against their teeth when facial length for the range of excursion required, is selected. The resting
movement is desired6. The patient's smile often resembles a tone of the transplanted muscle and quality of neurovascular
grimace, due to the mass movement or synkinesis when the anastomoses are important for functional recovery. A muscle
hypoglossal nerve simultaneously stimulates all the muscles7. restored to normal resting length, will have a normal resting tone
The hemiparesis of the tongue may also be problematical. Defi¬ at its new anatomical site12. A meticulous nerve repair, is carried
cits in speech and eating may occur, along with atrophy of the out as close to the transplanted muscle as possible, to minimize the
denervated half tongue, which is severe in 25% of the cases6-26. time needed for muscle reinnervation to occur. Experimental and
clinical evidence demonstrate that three hours of muscle ischemia
If a patient presents within 6-12 months of the onset of facial
is safe, and that up to four hours of ischemia does not affect the
paralysis, then a nerve repair or graft is the treatment of choice.
final outcome of a muscle transplant36. This allows for a careful
However, for a long standing paralysis, with absent, or atrophied
and well planned repositioning and revascularization of the donor
and fibrosed muscles, other reconstructive strategies are re¬
muscle. If all goes well, reinnervation, documented by EMG
quired27. In this situation, muscle transfers, which can provide
studies, may be apparent by as early as 6 weeks12.
functional and aesthetic improvement quickly, and are not as dif¬
ficult to perform surgically as many other procedures, are indi¬ The preferred muscle for facial reanimation at the Hospital for
cated. Muscle transfers using masseter, temporalis, platysma, Sick Children and Toronto General Hospital is currently the
frontalis, and sternocleidomastoid have been performed. gracilis37. Other muscles, such as serratus anterior, latissimus
Masseter and temporalis transfers have been the most successful dorsi, and pectoralis minor are also described as being useful. The
and popular of these procedures6 25. The insertion of the muscle to extensor digitorum brevis, based on the dorsalis pedis vessels, has
be transferred is dissected to a variable extent, and reattached by been used. However the contractile force of this muscle is gener¬
sutures to the area requiring reanimation. Usually the masseter is ally inadequate, and the results are poor10-27. The gracilis has an
used for smile reconstruction, with a new insertion created in the ideal neurovascular pedicle (6-7 cm), based on a central artery,
upper and lower lips and oral commissure. The temporalis may be paired venae comitantes, and the motor nerve to gracilis (a branch
of the obturator nerve). The donor deficit is unnoticeable, and the
used for either perioral or periocular reconstruction. Although
scar at the donor site is well hidden. The muscle itself can be
these procedures provide symmetry at rest and some voluntary
tailored to the correct size and shape needed38.
movement, there are several drawbacks. The origin of the trans¬
ferred muscle is fixed, therefore the muscle cannot be placed ex¬
Congenital facial palsies may be simple or complex. The com¬
actly where needed. The patient must be re-educated to use the
plex forms are part of syndromes, such as hemifacial microsomia
trigeminally innervated muscle for facial gesture by clenching
or Moebius syndrome (severe bilateral facial paralysis). Simple
teeth and moving their mandible. As with nerve transfer proce¬
or isolated cases generally have minimal functional problems,
dures, spontaneous tacial expression is impossible, and donor site with corneal protection and oral competence usually being ad-
10 University of Toronto Medical Journal