Controversies in the Management of Craniosynostosis

Richard A. Hopper; Gerald A. Grant; Richard G. Ellenbogen

doi:10.1055/s-2002-35250

Seminars in Neurosurgery, Table of Contents

Seminars in Neurosurgery 2002; 13(1): 081-096
DOI: 10.1055/s-2002-35250

Controversies in the Management of Craniosynostosis

Richard A. Hopper¹ , Gerald A. Grant² , Richard G. Ellenbogen²

¹Division of Craniofacial, Plastic and Reconstructive Surgery, Children's Hospital and Regional Medical Center and Department of Plastic and Reconstructive Surgery, University of Washington School of Medicine, Seattle, Washington
²Division of Neurological Surgery, Children's Hospital and Regional Medical Center, Department of Neurological Surgery, University of Washington School of Medicine, Seattle, Washington

Abstract

ABSTRACT

This article updates the general neurosurgeon on the current issues and controversies in craniofacial surgery. Topics discussed include differential diagnosis of posterior plagiocephaly, timing of craniosynostosis surgery, technical advances, intracranial pressure in craniosynostosis, and new technologies.

In the past decade, lambdoid synostosis has been overdiagnosed as a surgically treatable form of posterior plagiocephaly. Careful clinical examination can distinguish true lambdoid synostosis, which is rare, from nonsynostotic, deformational plagiocephaly which is much more common. The more common deformational plagiocephaly does not require surgical treatment.

Early surgery for craniosynostosis offers the benefit of secondary skull base improvements, by using the growing brain to mold the calvarium. There is also a decreased risk of persistent bone defects. These benefits must be balanced against data suggesting lower recurrence rates of suture closure with later or delayed surgery. There is also a growing trend in craniofacial centers toward more aggressive cranial remodeling with ancillary techniques to optimize the postoperative esthetic result. Endoscopic craniectomy is an exception to this rule, but in many cases this evolving technique requires intensive postoperative molding.

Bioresorbable plates and hydroxyapatite cements have a distinct role in craniofacial surgery; however, further analysis is required to understand the potential complications and appropriate indications for these new technologies.

KEYWORDS

Craniosynostosis - posterior plagiocephaly - deformational plagiocephaly - hydrocephalus - intracranial pressure - bioresorbable plates - bone substitutes

Full Text

References

REFERENCES

1 Gibson E, Fleming N, Fleming D. Sudden infant death syndrome rates subsequent to the American Academy of Pediatrics supine sleep position. Med Care . 1998; 36 938-942
2 Turk A E, McCarthy J G, Thorne C H. The ``back to sleep campaign'' and deformational plagiocephaly: is there cause for concern?. J Craniofac Surg . 1996; 7 12-18
3 Argenta L C, David L R, Wilson J A. An increase in infant cranial deformity with supine sleeping position. J Craniofac Surg . 1996; 7 5-11
4 Unkind cut: some physicians do unnecessary surgery on heads of infants when they remove lopsided skull when a corrective band is all that is needed: at fault, sleeping position. Wall Street Journal February 23, . 1996: A1
5 The epidemic that wasn't…scare faded under flare of scrutiny. Denver Post October 29, . 1995: A1
6 Bruneteau R J, Mulliken J B. Frontal plagiocephaly: synostotic, compensational, or deformational. Plast Reconstr Surg . 1992; 89 21-31
7 Rekate H L. Occipital plagiocephaly: a critical review of the literature. J Neurosurg . 1998; 89 24-30
8 Singer S, Bower C, Southall P. Craniosynostosis in Western Australia, 1980-1994; a population-based study. Am J Med Genet . 1999; 83 382-387
9 Huang M H, Gruss J S, Clarren S K. The differential diagnosis of posterior plagiocephaly: true lambdoid synostosis versus positional molding. Plast Reconstr Surg . 1996; 98 765-774
10 Muakkassa K F, Hoffman H J, Hinton D R. Lambdoid synostosis, II: Review of cases managed at The Hospital for Sick Children, 1972-1982. J Neurosurg . 1984; 61 340-347
11 McComb J G. Treatment of functional lambdoid synostosis. Neurosurg Clin North Am . 1991; 2 665-672
12 Jimenez D F, Barone C M, Argamaso R V. Asterion region synostosis. Cleft Palate Craniofac J . 1994; 31 136-141
13 Hinton D R, Becker L E, Muakkassa K F. Lambdoid synostosis, I: The lambdoid suture: normal development and pathology of ``synostosis''. J Neurosurg . 1984; 61 333-339
14 Dias M S, Klein D M, Backstrom J W. Occipital plagiocephaly: deformation or lambdoid synostosis?. <~>I: Morphometric analysis and results of unilateral lambdoid craniectomy. Pediatr Neurosurg . 1996; 24 61-68
15 Mulliken J B, Vander Woude L D, Hansen M. Analysis of posterior plagiocephaly: deformational versus synostotic. Plast Reconstr Surg . 1999; 103 371-380
16 David D J, Menard R M. Occipital plagiocephaly. Br J Plast Surg . 2000; 53 367-377
17 Vles J S, Colla C, Weber J W. Helmet versus nonhelmet treatment in nonsynostotic positional posterior plagiocephaly. J Craniofac Surg . 2000; 11 572-574
18 Kelly K M, Littlefield T R, Pomatto J K. Importance of early recognition and treatment of deformational plagiocephaly with orthotic cranioplasty. Cleft Palate Craniofac J . 1999; 36 127-130
19 Cohen Jr M M. Lambdoid synostosis is an overdiagnosed condition. Am J Med Genet . 1996; 61 98-99
20 Cohen Jr M M. Sutural biology and the correlates of craniosynostosis. Am J Med Genet . 1993; 47 581-616
21 Huang M H, Mouradian W E, Cohen S R. The differential diagnosis of abnormal head shapes: separating craniosynostosis from positional deformities and normal variants. Cleft Palate Craniofac J . 1998; 35 204-211
22 Kapp-Simon K A. Mental development in infants with nonsyndromic craniosynostosis with and without cranial release and reconstruction. Plast Reconstr Surg . 1994; 94 408-410
23 Kapp-Simon K A. Mental development and learning disorders in children with single suture craniosynostosis. Cleft Palate Craniofac J . 1998; 35 197-203
24 Sidoti Jr J E, Marsh J L, Marty-Grames L. Long-term studies of metopic synostosis: frequency of cognitive impairment and behavioral disturbances. Plast Reconstr Surg . 1996; 97 276-281
25 Speltz M L, Morton K, Goodell E W. Psychological functioning of children with craniofacial anomalies and their mothers: follow-up from late infancy to school entry. Cleft Palate Craniofac J . 1993; 30 482-489
26 Baum J D, Searls D. Head shape and size of preterm low-birthweight infants. Dev Med Child Neurol . 1971; 13 576-581
27 Vollmer D G, Jane J A, Park T S. Variants of sagittal synostosis: strategies for surgical correction. J Neurosurg . 1984; 61 557-562
28 Boop F A, Shewmake K, Chadduck W M. Synostectomy versus complex cranioplasty for the treatment of sagittal synostosis. Childs Nerv Syst . 1996; 12 371-375
29 Williams J K, Ellenbogen R G, Gruss J S. State of the art in craniofacial surgery: nonsyndromic craniosynostosis. Cleft Palate Craniofac J . 1999; 36 471-485
30 Panchal J, Marsh J L, Park T S. Sagittal craniosynostosis outcome assessment for two methods and timings of intervention. Plast Reconstr Surg . 1999; 103 1574-1584
31 Marsh J L, Jenny A, Galic M. Surgical management of sagittal synostosis: a quantitative evaluation of two techniques. Neurosurg Clin N Am . 1991; 2 629-640
32 Prevot M, Renier D, Marchac D. Lack of ossification after cranioplasty for craniosynostosis: a review of relevant factors in 592 consecutive patients. J Craniofac Surg . 1993; 4 247-254
33 Sutton L N, Barlett S P, Duhaime A C. Total cranial vault reconstruction for the older child with scaphocephaly. Pediatr Neurosurg . 1993; 19 63-72
34 Sloan G M, Wells K C, Raffel C. Surgical treatment of craniosynostosis: outcome analysis of 250 consecutive patients. Pediatrics . 1997; 100 E2
35 McCarthy J G, Glasberg S B, Cutting C B. Twenty-year experience with early surgery for craniosynostosis, I: Isolated craniofacial synostosis-results and unsolved problems. Plast Reconstr Surg . 1995; 96 272-283
36 Collmann H, Sorensen N, Krauss J. Consensus: trigonocephaly. Childs Nerv Syst . 1996; 12 664-668
37 Whitaker L A, Bartlett S P, Schut L. Craniosynostosis: an analysis of the timing, treatment, and complications in 164 consecutive patients. Plast Reconstr Surg . 1987; 80 195-212
38 Wall S A, Goldin J H, Hockley A D. Fronto-orbital reoperation in craniosynostosis. Br J Plast Surg . 1994; 47 180-184
39 Fearon J A, Kolar J C, Munro I R. Trigonocephaly-associated hypotelorism: is treatment necessary?. Plast Reconstr Surg . 1996; 97 503-509
40 Denis D, Genitori L, Conrath J. Ocular findings in children operated on for plagiocephaly and trigonocephaly. Childs Nerv Syst . 1996; 12 683-689
41 Williams J K, Cohen S R, Burstein F D. A longitudinal, statistical study of reoperation rates in craniosynostosis. Plast Reconstr Surg . 1997; 100 305-310
42 DiRocco C, Caldarelli M, Ceddia A. [Craniostenosis: analysis of 161 cases surgically treated during the first year of life]. Minerva Pediatr . 1989; 41 393-404
43 Marsh J L, Vannier M W. Cranial base changes following surgical treatment of craniosynostosis. Cleft Palate J . 1986; S9-S18
44 Perlyn C A, Marsh J L, Pilgram T K. Plasticity of the endocranial base in nonsyndromic craniosynostosis. Plast Reconstr Surg . 2001; 108 294-301
45 McCarthy J G, Glasberg S B, Cutting C B. Twenty-year experience with early surgery for craniosynostosis, II: The craniofacial synostosis syndromes and pansynostosis-results and unsolved problems. Plast Reconstr Surg . 1995; 96 284-295
46 Bruce D A. Consensus: craniofacial synostoses: Apert and Crouzon syndromes. Childs Nerv Syst . 1996; 12 734-736
47 Renier D, Lajeunie E, Arnaud E. Management of craniosynostoses. Childs Nerv Syst . 2000; 16 645-658
48 Posnick J C, Ruiz R L. The craniofacial dysostosis syndromes: current surgical thinking and future directions. Cleft Palate Craniofac J . 2000; 37 433
49 Tuite G F, Chong W K, Evanson J. The effectiveness of papilledema as an indicator of raised intracranial pressure in children with craniosynostosis. Neurosurg . 1996; 38 272-278
50 Gobiet W, Stahl E W, Bock W J, Grote W. Direct measurements of ICP in cases of craniosynostosis as a diagnostic aid for operation. In: Becks JWF, Bosch DA, Brock M, eds. Intracranial pressure Vol 3. Berlin, Heidelberg, New York: Springer 1976: 336-339
51 Van Effenterre R, Houtteville J P, Philippon J. Interet de la mesure de la pression intra-cranienne dans les craniostenoses decouvertes agres l'age d'un an. Neurochirurgie . 1976; 22 59-67
52 Reiner D, Sainte-Rose C, Marchac D, Hirsch J-F. Intracranial pressure in craniostenosis. J Neurosurg . 1982; 57 370-377
53 Whittle I R, Johnston I H, Besser M. Intracranial pressure changes in craniosynostosis. Surg Neur . 1984; 21 367-372
54 Gault D T, Reiner D, Marchac D, Jones B. Intracranial pressure and intracranial volume in children with craniosynostosis. Plast Reconst Surg . 1991; 90 377-381
55 Fok H, Jones B M, Gault D G, Andar U, Hayward R. Relationship between intracranial pressure and intracranial volume in craniosynostosis. Br J Plast Surg . 1992; 45 394-397
56 Thompson D NP, Malcolm G P, Jones B M, Harkness W J, Hayward R D. Intracranial pressure in single suture craniosynostosis. Ped Neurosurg . 1995; 22 235-240
57 Thompson D NP, Harkness W, Jones B, Gonsalez S, Andar U, Hayward R. Subdural intracranial pressure monitoring in craniosynostosis: its role in surgical management. Childs Nerv Syst . 1995; 11 269-275
58 Thompson D N, Harkness W, Jones B M, Hayward R D. Aetiology of herniation of the hindbrain in craniosynostosis: an investigation incorporating intracranial pressure monitoring and magnetic resonance imaging. Pediatr Neurosurg . 1997; 26 288-295
59 David L R, Genecov D G, Camastra A A, Wilson J A, Argenta L C. Positron emission tomography studies confirm the need for early surgical intervention in patients with single-suture craniosynostosis. J Craniofacial Surg . 1999; 10 38-42
60 Arnaud E, Reiner D, Marchac D. Prognosis for mental function in scaphocephaly. J Neurosurg . 1995; 83 476-479
61 Gewalli F, Guimaraes-Ferreira J P, Sahlin P. Mental development after modified pi procedure: dynamic cranioplasty for sagittal synostosis. Ann Plast Surg . 2001; 46 415-420
62 Hudgins R J, Cohen S R, Burstein F D, Boydston W R. Multiple suture synostosis and increased intracranial pressure following repair of single suture, nonsyndromal craniosynostosis. Cleft Palate Craniofac J . 1998; 35 167-172
63 Pollack I F, Losken H W, Biglan A W. Incidence of increased intracranial pressure after early surgical treatment of syndromic craniosynostosis. Pediatr Neurosurg . 1996; 24 202-209
64 Guimaraes-Ferreira J, Gewalli F, David L. Clinical outcome of the modified pi-plasty procedure for sagittal synostosis. J Craniofac Surg . 2001; 12 218-224
65 McComb J G. Occipital reduction-biparietal widening technique for correction of sagittal synostosis. Pediatr Neurosurg . 1994; 20 99-106
66 Epstein N, Epstein F, Newman G. Total vertex craniectomy for the treatment of scaphocephaly. Childs Brain . 1982; 9 309-316
67 Maugans T A, McComb J G, Levy M L. Surgical management of sagittal synostosis: a comparative analysis of strip craniectomy and calvarial vault remodeling. Pediatr Neurosurg . 1997; 27 137-148
68 Hoffman H J. Editorial comment. Child Nerv Syst . 1996; 12 375
69 Jimenez D F, Barone C M. Endoscopic craniectomy for early surgical correction of sagittal craniosynostosis. J Neurosurg . 1998; 88 77-81
70 Barone C M, Jimenez D F. Endoscopic craniectomy for early correction of craniosynostosis. Plast Reconstr Surg . 1999; 104 1965-1973
71 Johnson J O, Jimenez D F, Barone C M. Blood loss after endoscopic strip craniectomy for craniosynostosis. J Neurosurg Anesthesiol . 2000; 12 60
72 Jimenez D F. Endoscopic craniosynostosis reconstruction. New York: Craniofacial surgery: the new millenium 2001
73 Hoffman H J, Mohr G. Lateral canthal advancement of the supraorbital margin: a new corrective technique in the treatment of coronal synostosis. J Neurosurg . 1976; 45 376-381
74 Machado H R, Hoffman H J. Long-term results after lateral canthal advancement for unilateral coronal synostosis. J Neurosurg . 1992; 76 401-406
75 Hoffman H J. Procedure of lateral canthal advancement for the treatment of coronal synostosis. Childs Nerv Syst . 1996; 12 678-682
76 Hansen M, Mulliken J B. Frontal plagiocephaly: diagnosis and treatment. Clin Plast Surg . 1994; 21 543-553
77 Whitaker L A, Bartlett S P. The craniofacial dysostoses: guidelines for management of the symmetric and asymmetric deformities. Clin Plast Surg . 1987; 14 73-81
78 Genitori L, Zanon N, Denis D. The skull base in plagiocephaly. Childs Nerv Syst . 1994; 10 217-223
79 Marsh J L, Gado M H, Vannier M W. Osseous anatomy of unilateral coronal synostosis. Cleft Palate J . 1986; 23 87-100
80 Jane J A, Park T S, Zide B M. Alternative techniques in the treatment of unilateral coronal synostosis. J Neurosurg . 1984; 61 550-556
81 Muhling J, Reuther J, Sorensen N. Problems with lateral canthal advancement. Childs Nerv Syst . 1986; 2 287-289
82 Bartlett S P, Whitaker L A, Marchac D. The operative treatment of isolated craniofacial dysostosis (plagiocephaly): a comparison of the unilateral and bilateral techniques. Plast Reconstr Surg . 1990; 85 677-683
83 Sgouros S, Goldin J H, Hockley A D. Surgery for unilateral coronal synostosis (plagiocephaly): unilateral or bilateral correction?. J Craniofac Surg . 1996; 7 284-289
84 Laurent J P, Balasubramaniam C, Stal S. Early surgical management of coronal synostosis. Clin Plast Surg . 1990; 17 183-187
85 Polley J W, Charbel F T, Kim D. Nonsyndromal craniosynostosis: longitudinal outcome following cranio-orbital reconstruction in infancy. Plast Reconstr Surg . 1998; 102 619-632
86 Posnick J C. Unilateral coronal synostosis (anterior plagiocephaly): current clinical perspectives. Ann Plast Surg . 1996; 36 430-447
87 Marchac D, Renier D. [The ``floating forehead'': early treatment of craniofacial stenosis]. Ann Chir Plast . 1979; 24 121-126
88 McCarthy J G, Coccaro P J, Eptstein F. Early skeletal release in the infant with craniofacial dysostosis: the role of the sphenozygomatic suture. Plast Reconstr Surg . 1978; 62 335-346
89 Persing J A, Jane J A, Park T S. Floating C-shaped orbital osteotomy for orbital rim advancement in craniosynostosis: preliminary report. J Neurosurg . 1990; 72 22-26
90 Marsh J L, Schwartz H G. The surgical correction of coronal and metopic craniosynostoses. J Neurosurg . 1983; 59 245-251
91 Sadove A M, Kalsbeck J E, Eppley B L. Modifications in the surgical correction of trigonocephaly. Plast Reconstr Surg . 1990; 85 853-858
92 Jackson I T, Costanzo C, Marsh W R. Orbital expansion in plagiocephaly. Br J Plast Surg . 1988; 41 16-19
93 Habal M B. A specialist's view of the new technology: the absorbable plating system. J Craniofac Surg . 1997; 8 83
94 Eppley B L. Resorbable biotechnology for craniomaxillofacial surgery. J Craniofac Surg . 1997; 8 85-86
95 Goldberg D S, Bartlett S, Yu J C. Critical review of microfixation in pediatric craniofacial surgery. J Craniofac Surg . 1995; 6 301-307
96 New York: Craniofacial surgery: the new millenium, 2001 .
97 International Society of Craniofacial Surgery. Nineteenth International Congress, 2001 Visby, Gotland, Sweden
98 Imola M J, Hamlar D D, Shao W. Resorbable plate fixation in pediatric craniofacial surgery: long-term outcome. Arch Facial Plast Surg . 2001; 3 79-90
99 Kumar A V, Staffenberg D A, Petronio J A. Bioabsorbable plates and screws in pediatric craniofacial surgery: a review of 22 cases. J Craniofac Surg . 1997; 8 97-99
100 Kurpad S N, Goldstein J A, Cohen A R. Bioresorbable fixation for congenital pediatric craniofacial surgery: a 2-year follow-up. Pediatr Neurosurg . 2000; 33 306-310
101 Eppley B L, Sadove A M, Havlik R J. Resorbable plate fixation in pediatric craniofacial surgery. Plast Reconstr Surg . 1997; 100 1-7
102 Cohen S R, Holmes R E. Internal Le Fort III distraction with biodegradable devices. J Craniofac Surg . 2001; 12 264-272
103 Eppley B L. Potential for guided bone regeneration and bone graft fixation with resorbable membranes in pediatric craniofacial surgery. J Craniofac Surg . 1997; 8 127-128
104 Cohen S R, Holmes R E, Amis P. Internal craniofacial distraction with biodegradable devices: early stabilization and protected bone regeneration. J Craniofac Surg . 2000; 11 354-366
105 Burstein F D. Bone substitutes. Cleft Palate Craniofac J . 2000; 37 1-4
106 Costantino P D, Friedman C D, Jones K. Hydroxyapatite cement, I: Basic chemistry and histologic properties. Arch Otolaryngol Head Neck Surg . 1991; 117 379-384
107 Costantino P D, Friedman C D, Jones K. Experimental hydroxyapatite cement cranioplasty. Plast Reconstr Surg . 1992; 90 174-185
108 Burstein F D, Cohen S R, Hudgins R. The use of hydroxyapatite cement in secondary craniofacial reconstruction. Plast Reconstr Surg . 1999; 104 1270-1275
109 Costantino P D, Chaplin J M, Wolpoe M E. Applications of fast-setting hydroxyapatite cement: cranioplasty. Otolaryngol Head Neck Surg . 2000; 123 409-412
110 Kurashina K, Kurita H, Hirano M. In vivo study of calcium phosphate cements: implantation of an alpha-tricalcium phosphate/dicalcium phosphate dibasic/tetracalcium phosphate monoxide cement paste. Biomaterials . 1997; 18 539-543
111 Kamerer D B, Hirsch B E, Snyderman C H. Hydroxyapatite cement: a new method for achieving watertight closure in transtemporal surgery. Am J Otol . 1994; 15 47-49
112 Maniker A, Cantrell S, Vaicys C. Failure of hydroxyapatite cement to set in repair of a cranial defect: case report. Neurosurgery . 1998; 43 953-954
113 Genecov D G, Kremer M, Salyer K E. Norian compatibility with bioresorbable plating materials: an animal model. Nineteenth International Congress of the International Society of Craniofacial Surgery, 2001, Visby, Sweden
114 Lykins C L, Friedman C D, Costantino P D. Hydroxyapatite cement in craniofacial skeletal reconstruction and its effects on the developing craniofacial skeleton. Arch Otolaryngol Head Neck Surg . 1998; 124 153-159
115 Gosain A K. Hydroxyapatite cement paste cranioplasty for the treatment of temporal hollowing after cranial vault remodeling in a growing child. J Craniofac Surg . 1997; 8 506-511
116 Aronson J, Shen X. Experimental healing of distraction osteogenesis comparing metaphyseal with diaphyseal sites. Clin Orthop . 1994; 301 25-30
117 Ilizarov G A, Deviatov A A. [Surgical lengthening of the shin with simultaneous correction of deformities]. Ortop Travmatol Protez . 1969; 30 32-37
118 Ilizarov G A. Clinical application of the tension-stress effect for limb lengthening. Clin Orthop . 1990; 250 8-26
119 McCarthy J G, Schreiber J, Karp N. Lengthening the human mandible by gradual distraction. Plast Reconstr Surg . 1992; 89 1-8
120 Rachmiel A, Potparic Z, Jackson I T. Midface advancement by gradual distraction. Br J Plast Surg . 1993; 46 201-207
121 Glat P M, Staffenberg D A, Karp N S. Multidimensional distraction osteogenesis: the canine zygoma. Plast Reconstr Surg . 1994; 94 753-758
122 Baird C, Fewings P, Manepalli A. Cranial vault expansion: a comparison of magnetic coupled distraction to traditional surgical repositioning. Pediatr Neurosurg . 2000; 33 2-6
123 Pittman T, Rinehart G C, Hagen R. Cranial vault moulding by the transcutaneous activation of implanted magnets. Pediatr Neurosurg . 1997; 27 78-83
124 Rinehart G, Forget T, Zografakis J. Cranial vault expansion using transcutaneously activated magnetic implants. Pediatr Neurosurg . 1998; 28 293-299
125 Tschakaloff A, Losken H W, Mooney M P. Internal calvarial bone distraction in rabbits with experimental coronal suture immobilization. J Craniofac Surg . 1994; 5 318-326
126 Persing J A, Babler W J, Nagorsky M J. Skull expansion in experimental craniosynostosis. Plast Reconstr Surg . 1986; 78 594-603
127 Lauritzen C, Friede H, Elander A. Dynamic cranioplasty for brachycephaly. Plast Reconstr Surg . 1996; 98 7-14
128 Sugawara Y, Hirabayashi S, Sakurai A. Gradual cranial vault expansion for the treatment of craniofacial synostosis: a preliminary report. Ann Plast Surg . 1998; 40 554-565
129 Lauritzen C, Sugawara Y, Kocabalkan O. Spring mediated dynamic craniofacial reshaping: case report. Scand J Plast Reconstr Surg Hand Surg . 1998; 32 331-338
130 Kobayashi S, Honda T, Saitoh A. Unilateral coronal synostosis treated by internal forehead distraction. J Craniofac Surg . 1999; 10 467-471
131 Matsumoto K, Nakanishi H, Seike T. Application of the distraction technique to scaphocephaly. J Craniofac Surg . 2000; 11 172-176