- Email: [email protected]
Cosmetic concerns in pediatric craniofacial surgery
Neurosurg Clin N Am 13 (2002) 505–513
Cosmetic concerns in pediatric craniofacial surgery Deepak Narayan, MD, John. A. Persing, MD* Section of Plastic Surgery, 330, Cedar Street, Boardman Building-330, New Haven, CT 06520, USA
This article highlights the technical details of the authors’ techniques in the surgical management of craniosynostosis. The role of orthotic devices vis-a vis positional plagiocephaly and postsurgical molding is discussed. A method of avoiding temporal hollowing in cranioplasty is presented. This article focuses on various technical aspects of pediatric craniofacial surgery that we have used in practice to optimize the cosmetic quality of the outcome. Craniosynostosis surgery The correction of premature sutural closure is performed primarily for two reasons: normalization of the skull deformity and reduction of intracranial pressure. Renier [1] and Thompson et al [2]. The procedure adopted depends on the suture that is fused, the age of the patient, and the associated anomalies present. Highlights of the techniques used for the various forms of craniosynostosis in our practice are presented below. Sagittal synostosis Sagittal synostosis remains the most commonly encountered form of craniosynostosis. The simplest form of surgical treatment for this disorder is the strip or linear craniectomy, where the prematurely fused suture is excised in the hope that once the restrictive force is released, the brain will expand and the skull will then mold itself into a more normal shape. In terms of the degree of correction obtained, the results of this procedure are * Corresponding author. E-mail address: [email protected] (J.A. Persing).
suboptimal compared with those of the more comprehensive cranioplasty procedures [3]. There may still be a place for the strip craniectomy, however, in the mild and early forms of sagittal synostosis. The procedure’s primary appeal rests on its simplicity and, in some cases, effectiveness, particularly if coupled with a skull molding cap. The advantages of this approach lie in the smaller scar and potentially lesser blood loss, which have to be balanced against a less complete correction and the need for prolonged (approximately 1 year) use of a skull molding cap. For most cases of more advanced sagittal synostosis, the cardinal features of our cranioplasty technique are (1) release of sutural stenosis, (2) remodeling of cranial bone, (3) active reduction of the abnormally long dimension of the skull, and (4) active expansion of abnormally narrow areas [4]. The technique we currently favor in children less than 1 year of age is a modification of the p procedure originally described by Jane and Persing [4]. The patient is placed in a modified prone position [5], which allows easy access to the anterior and posterior skull. A frontal craniotomy is performed with the cephalad osteotomy posterior to the hairline, followed by separate parietal and parieto-occipital osteotomies. The squamous part of the temporal bone is out-fractured along with the overlying temporalis. The frontal and occipital bossing is reduced by radial osteotomies, and the parietal bone is remodeled in a similar fashion to produce a more convex form. The anteroposterior (AP) dimensions are reduced by 1 to 1.5 cm by removal of a segment of bone in the midline, and the frontal bone is attached to the supraorbital rim with removal of triangular wedges of bone laterally to allow posterior tilting of the forehead (Fig. 1).
1042-3680/02/$ - see front matter Ó 2002, Elsevier Science (USA). All rights reserved. PII: S 1 0 4 2 - 3 6 8 0 ( 0 2 ) 0 0 0 2 2 - 0
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D. Narayan, J.A. Persing / Neurosurg Clin N Am 13 (2002) 505–513
Fig. 1. Sagittal synostosis: operative detail. (Top panel) (1) Frontal craniotomy and osteotomy, (2) parietal osteotomy, (3) occipital osteotomy, and (4) temporal bone out-fracture. (Lower panel) Fixation of radially osteotomized segments and reduction of anteroposterior diameter. Note removal of triangular wedge of bone. (Modified from Cohen MM, MacLean RE, editors. Craniosynostosis—diagnosis, evaluation and management. 2nd edition. New York: Oxford University Press; 2000:215; with permission.)
The ‘‘brittleness’’ of the bones in children older than 1 year of age prevents remodeling as described previously. In such instances, we have modified the approach described by Marchac and Renier [6], wherein serial osteotomies are performed anteriorly to posteriorly, with the most basal frontal osteotomy being performed at the height of the forehead, followed by serial posterior frontoparietal and parieto-occipital osteotomies (Fig. 2) [4], with a reversal of the midparietal and posterior frontal bone if required. Kerfs (Fig. 3) are placed on the inner surface of the bone seg-
Fig. 2. Sagittal synostosis (late treatment). (From Cohen MM, MacLean RE, editors. Craniosynostosis— diagnosis, evaluation and management. 2nd edition. New York: Oxford University Press; 2000:215; with permission.)
ments to allow for remodeling. Although the illustrations depict the use of sutures (wires), we now use absorbable plating systems, which are particularly useful in decreasing the length of the skull and achieving a wider biparietal diameter. Metopic synostosis The metopic suture is the first to fuse in the normal calvarium. Premature fusion of the metopic
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Fig. 3. Placement of kerfs. (From Persing JA, Edgerton MT, Jane JA, editors. Scientific foundations and surgical treatment of craniosynostosis. Baltimore: Williams & Wilkins; 1989:164–5; with permission.)
suture results in trigonocephaly and hypotelorism. The three anatomic features that mark this condition are deficiency of the projection of the lateral orbital rims, recession of the lateral frontal bone, and narrowing of the squamous part of the temporal bone. Because a wide range of acceptable appearances may result from this process, operative intervention requires careful judgment. A prominent metopic ridge, for instance, in the absence of the other hallmarks of metopic synostosis can merely be burred down to restore a normal contour. Our approach to more evident trigonocephaly involves bilateral orbital rim osteotomies as well as a bifrontal osteotomy performed to the level of the hairline (Fig. 4). Temporalis myo-osseous flaps are raised, and these are advanced to support the repositioned orbital rims and provide more fullness in the temporal squamous area. The bifrontal graft is remodeled using radial osteotomies and Tessier rib benders.
Coronal synostosis Coronal synostosis may present with unilateral or bilateral fusion of the sutures. The clinical features of unilateral coronal synostosis are distinct from the bilateral form and are described individually, because each of these features needs to be addressed separately. In unilateral coronal synostosis, on the side of the fused coronal suture:
1. The frontal and parietal bones are flattened. 2. The orbital rim is recessed, and the mediolateral width of the orbit is smaller than the opposite side. 3. The temporal squamous bone is protuberant. 4. The ear is anteriorly displaced. 5. The contralateral frontal bone is unduly prominent. 6. The orbital rim is depressed inferiorly compared with the orbital rim on the fused side. Additional findings include mandibular asymmetry (mandibular midline deviated to the side opposite the synostosis) and deviation of the nasal radix to the ipsilateral side. These are usually minor and rarely require surgical correction. Surgical correction involves performing a coronal incision in the supraperiosteal plane to the orbital rims, at which level the dissection is continued in a subperiosteal plane intraorbitally. The patent coronal suture at the fontanelle on the contralateral side is used as access for a craniotomy. A bifrontoparietal craniotomy with radial osteotomies is performed in children less than 1 year of age. In children 1 year of age or older, the deformed frontal bone on the affected side may be replaced by parietal bone graft harvested by a separate biparietal osteotomy, followed by trimming of the greater wing of the sphenoid on the side of the affected suture. The orbital rims are reshaped with burrs to attain a normal form. Internal support for the newly fashioned orbital rim is provided for by a
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Fig. 4. Metopic synostosis. (Top panel) Frontoparietal osteotomy and burring down of metopic prominence. (Lower panel) Fixation to orbital rim. (From Persing JA, Edgerton MT, Jane JA, editors. Scientific foundations and surgical treatment of craniosynostosis. Baltimore: Williams & Wilkins; 1989:164–5; with permission.)
separate bone graft—the bowstring procedure. The composite temporalis myo-osseous flap (see below) is used to prevent temporal hollowing after the orbital rims are attached to the midline and laterally at the frontozygomatic suture (Fig. 5). Molding of bone in older children is done using kerfs on the endocranial surface of the skull. In patients with localized residual defects or in patients who are not desirous of extensive surgery, we have used methylmethacrylate or a bone paste to reconstruct the defects. Bilateral coronal synostosis The turricephalic skull resulting from bilateral coronal synostosis can present in either a nonsyndromic or syndromic form, where it may be associated with craniofacial syndromes such as
Apert’s, Crouzon’s, or Pfeiffer’s. A modified prone position is used to provide simultaneous access to the anterior and posterior skull. Cervical spine films and, in the case of craniofacial syndromes, MRI are obtained to determine cervical spine instability and the presence of an Arnold-Chiari malformation, respectively. The presence of these conditions dictates the use of a staged cranioplasty technique. The key features of the one-stage operative procedure are illustrated in Fig. 6. A bifrontal craniotomy is performed at the level of the forehead. A disk of bone is left attached to the vertex of the skull with two parietal struts as shown. Separate parietal craniotomies are also carried out. Occipital barrel stave osteotomies are performed and out-fractured to increase the AP dimensions. The orbital rims are replaced after contouring with the temporal flap,
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Fig. 5. Coronal synostosis. (Top panel) Frontoparietal osteotomy. (Middle panel) Radial osteotomy and remolding. (Lower panel) Fixation of osteotomized fragments. (From Persing JA, Edgerton MT, Jane JA, editors. Scientific foundations and surgical treatment of craniosynostosis. Baltimore: Williams & Wilkins; 1989:164–5; with permission.)
holding it in position. The height of the skull is reduced between 1 and 2 cm depending on the correction required by cinching the basal and parietal bones together (see Fig. 6, lower panel), and forehead projection is reduced by posterior migration/ movement of parietal struts.
Prevention of temporal hollowing Orbital rim advancement in coronal and metopic synostosis, although enhancing periorbital esthetics, commonly creates an unattractive temporal depression. Various methods are used
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temporal hollowing based on the creation of a temporalis myo-osseous flap [7]. A brief description of our technique is given below (Fig. 7). A burr hole is placed superior to the superior temporal line, giving access to the epidural space, and a bifrontal craniotomy is performed. The temporalis muscle is then minimally dissected off the posterior portion of the zygomatic process of the frontal bone (0.5–1 cm) to allow access to osteotomize the lateral orbital roof. With epidural dissection and the orbital rim removal completed, the most posterior aspect of the temporalis muscle is divided. The division is done in line with the orientation of the muscle fibers superior and posterior to the pinna. A vertical osteotomy is performed anterior to this line. One limb of a Gigli’s wire saw or Midas Rex bit is placed in the osteotomy site in the posterior squamous portion of the temporal bone. Another is placed in the osteotomy site in the region of the pterion. The squamous temporal bone and its overlying temporalis muscle are elevated out of the temporal fossa with a saw cut of the squamous temporal bone, yielding a myoosseous flap. The temporal fossa is then cleared of the remaining temporalis muscle, and the superior portion of the greater wing of the sphenoid is trimmed for easier inset of the flap. For patients with metopic synostosis, the remaining basolateral sphenoid wing is split sagittally. Barrel stave osteotomies and lateral fractures of the temporal and lateral sphenoid bones are performed to increase projection locally. In coronal synostosis, the posterior bone segments undergo in-fracture to decrease projection. Fig. 6. Bilateral coronal synostosis. A biparieto-occipital bone graft is developed posteriorly with a bone bridge between the two hemicrania located below the level of the torcula. The remaining occipital bone undergoes barrel stave osteotomy. (From Cohen MM, MacLean RE, editors. Craniosynostosis—diagnosis, evaluation and management. 2nd edition. New York: Oxford University Press; 2000:215; with permission.)
to counteract this deformity, including filling the hollow with bone chips and posterior detachment of the temporalis muscle to rotate it anteriorly either unfolded or folded over itself to add additional bulk to obliterate the hollow. Although these techniques may prevent hollowing to some degree initially, the long-term results are unsatisfactory. We have described a technical innovation that provides a reliable method for the prevention of
Lambdoid synostosis The increased incidence of deformational plagiocephaly (see below) has caused considerable confusion in the diagnosis of lambdoid synostosis. Typically, unilateral lambdoid synostosis is characterized by a flattening of the ipsilateral parietal occiput asymmetry at the base of the skull and posterior and inferior displacement of the ipsilateral ear. Radiologically, a deviation of the foramen magnum to the affected side and premature fusion of the lambdoid suture are demonstrable. Rarely, it may mimic the deformational plagiocephaly skull pattern but differs in that it is progressive and nonremitting despite conservative methods, such as physical therapy and skull molding helmet use. The parieto-occiput is removed as a single unit with a coronal suture, providing access. The major
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Fig. 7. Prevention of temporal hollowing. (1) Burr hole made at superior temporal line, (2) bifrontal craniotomy is performed, (3) temporalis fascia is detached from posterolateral orbital rim, (4) orbital rim is elevated and advanced, (5) osteotomy in the greater wing of the sphenoid is deepened in the sagittal plane with a sagittal saw, (6) temporalis muscle fibers are divided in a plane parallel to their orientation, (7) osteotomy of squamous part of temporal bone is performed, (8) Gigli saw osteotomy preserves temporalis attachment to bone, (9) musculo-osseous flap is reflected laterally, (10) 2–3 mm of squamous temporal bone is removed by rongeur to allow anterior rotation of bone without overlap, (11) barrel staves are fractured laterally in the anterior squamous temporal region and medially in the posterior region (in coronal synostosis), (12) musculo-osseous flap is attached anteriorly, (13) musculo-osseous flap is attached to the advanced orbital rim, and (14) musculo-osseous flap is attached to the reshaped frontal bone. (From Cohen MM, MacLean RE, editors. Craniosynostosis—diagnosis, evaluation and management. 2nd edition. New York: Oxford University Press; 2000:215; with permission.)
venous structures, such as the torcula and sagittal and transverse sinuses, make this a particularly tedious dissection. Radial osteotomies are performed on the piece removed, whereas barrel stave osteotomies are performed on the calvarium basal to the parieto-occiput. Contralateral to the fused suture, the staves are fractured inward, whereas, ipsilaterally, they are fractured outward. Bilateral lambdoid synostosis is vanishingly rare in isolation from craniofacial syndromes.
Correction of positional molding Positional or deformational plagiocephaly is a term that is applied to an abnormal head shape in an infant that develops as a result of positional molding of the cranium unrelated to premature sutural fusion. A variety of factors have been implicated in the development of this deformity, including a restrictive intrauterine environment, birth trauma, torticollis, cervical anomalies,
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sleepingposition, lackof full mineralization, neurologic factors, or a combination of these factors [8]. In 1992, the American Academy of Pediatrics [9] issued a recommendation that infants be positioned to sleep either on their back or sides to reduce the risk of sudden infant death syndrome (SIDS). Subsequently, multiple centers noted an increase in craniofacial deformities of nonsynostotic origin, although this had a beneficial effect in reducing the number of deaths related to SIDS. Supine positioning is to be condemned, but frequent position changes in the earliest stages of life may reduce the likelihood of skull deformities. Appropriate management of positional deformities, once formed, include simple repositioning of the infant, avoidance of prolonged periods of rest in one position, exercises to increase the range of movement of the neck, and the use of orthotic devices. Planned cranial deformation has been used for centuries by various cultures. Literature describing the therapeutic effect of orthotic devices is available [8,10,11]; however, a criticism leveled against published studies is that they lack appropriate controls. In other words, it is not known whether simple repositioning and exercising of the infant alone can produce the results achieved with the use of orthotic devices. The general impression is that properly designed and applied devices are more effective and rapid in reducing skull deformities, however. Potential risks to health associated with this type of device include (1) skin irritation, breakdown, and subsequent infection; (2) head and neck trauma caused by alteration of the functional center of the mass of the head; (3) impairment of brain growth and development from mechanical restriction of cranial growth; (4) eye trauma caused by mechanical failure or poor fit; and (5) contact dermatitis [12]. We believe that helmets have a role, particularly in the severely deformed skull, in patients who have the condition when exercises are either ineffective or not followed, in patients with gastric reflux precluding prone positioning even while supervised, and in older infants ([9 months of age) and those with significant facial deformity.
Resorbable materials The use of resorbable plates in the fixation of the craniofacial skeleton represents a major advance in the field, particularly in the pediatric
age group. The advantages are inherent in the biodegradability of the product. Concerns about long-term visibility of the plates in thin skinned individuals, malpositioned implants, or the effects of intracranial migration are mitigated. The plates are generally thicker than their metal counterparts and are therefore more easily palpable in the early postoperative stages. A representative series describing the use of bioresorbable fixation in pediatric craniofacial surgery is that described by Kurpad et al [13]. The first bioabsorbable fixation system for the craniofacial skeleton approved by the US Food and Drug Administration was the Lorenz Lactosorb system (Walter Lorenz, Jacksonville, FL) [14–16]. The material used, Lactosorb, is a copolymer of L-lactic acid (which is slowly absorbed, thus providing strength) and glycolic acid (which is rapidly absorbed) at a ratio of 82:18. This, being substantially amorphous, has marked advantages in terms of long-term stability and degradation compared with implants made of the pure forms of its component chemicals. Clinical complications, such as pronounced fibrous encapsulation, sterile abscess and sinus formation, and bone osteolysis, have been reported for the homopolymers. One of the few studies showing a reaction to a copolymer (sinus formation) involved polyglactin 910, a copolymer with an almost inverse ratio of polylactic acid and polygalactic acid compared with Lactosorb. In vivo, the material has been histologically demonstrated to be eliminated by approximately 1 year. Implants of another bioabsorbable product, MacroPore (Macropore Biosurgery, San Diego, CA), are manufactured from medical grade 100% amorphous 70:30 poly(Llactide-co-D,L-lactide). This is produced from a mixture of 70% L-lactide and 30% DL-lactide, which retains approximately 70% of its initial strength after 9 months and approximately 50% after 12 months, converts into carbon dioxide and water by the process of bulk hydrolysis, and resorbs completely in approximately 18 to 36 months. The use of bioabsorbable materials has now extended to the construction of distraction devices. Cohen and Holmes [17] describe their experience with biodegradable mesh Macropore as a substitution for metallic fixation plates. In discussing distraction in a 4-year-old with Crouzon’s syndrome, the clinical results achieved by this device are equivalent to those achieved by the metal counterpart with the added advantage of permitting internal distraction without the need for complete removal of the fixation device.
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Our experience with distraction devices for midface advancement has been favorable to date. We have obtained 30 mm of midface advancement using these devices.
[8]
[9]
References [1] Renier D. Intracranial pressure in craniosynostosis: pre and postoperative recordings—correlation with functional results. In: Persing J, Edgerton M, Jane J, editors. Scientific foundations and surgical treatment of craniosynostosis. Baltimore: Williams & Wilkins; 1989. p. 263–9. [2] Thompson DNP, Malcom GP, Jones BM, et al. Intracranial pressure in single suture craniosynostosis. Pediatr Neurosurg 1995;22:235–40. [3] Panchal J, Marsh JL, Park TS, et al. Sagittal craniosynostosis outcome assessment for two methods and timings of intervention. Plast Reconstr Surg 1999;103:1574–84. [4] Jane JA, Persing J. Neurosurgical treatment of craniosynostosis. In: Cohen MM, MacLean RE, editors. Craniosynostosis—diagnosis, evaluation and management. New York: Oxford University Press; 2000. p. 209–27. [5] Park TS, Haworth CS, Jane JA, et al. Modified prone position for cranial remodeling in children with craniofacial dysmorphism. Neurosurgery 1985;16: 212–4. [6] Marchac D, Renier M. Craniofacial surgery in craniosynostosis. Boston: Little Brown & Company; 1982. [7] Persing JA, Mayer PL, Spinelli HM, et al. Prevention of temporal hollowing after fronto orbital
[10]
[11]
[12] [13]
[14]
[15] [16]
[17]
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advancement for craniosynostosis. J Craniofac Surg 1994;5:271–4. Ripley CE, Pomatto J, Beals SP, et al. Treatment of positional plagiocephaly with dynamic orthotic cranioplasty. J Craniofac Surg 1994;5:150–9. Anonymous. American Academy of Pediatrics task force on infant positioning and SIDS. Pediatrics 1992;89:1120–6. Kelly KM, Littlefield TR, Pomatto JK, et al. Importance of early recognition and treatment of deformational plagiocephaly with orthotic cranioplasty: cleft palate. Craniofac J 1997;36:127–30. Kelly KM, Littlefield TR, Pomatto JK, et al. Cranial growth unrestricted during treatment of deformational plagiocephaly. Pediatr Neurosurg 1999;30: 193–9. Federal Register, vol. 63, no. 146. 21CFR, part 882, July 1998. Kurpad SN, Goldstein JA, Cohen AR. Bioresorbable fixation for congenital pediatric craniofacial surgery. Pediatr Neurosurg 2000;33:306–10. Pietrzak WS, Verstynen ML, Sarver DR. Bioabsorbable fixation devices: status for the craniomaxillofacial surgeon. J Craniofac Surg 1997;8:92–6. Pietrzak WS. Critical concepts of absorbable internal fixation. J Craniofac Surg 2000;11:335–41. Rubin PJ, Yaremchuk MJ. Complications and toxicities of implantable biomaterials used in facial reconstructive and aesthetic surgery. A comprehensive review of the literature. Plast Reconstr Surg 1997;100:1336–53. Cohen SR, Holmes RE. Internal LeFort III distraction with biodegradable devices. J Craniofac Surg 2001;12:264–72.
Cosmetic concerns in pediatric craniofacial surgery Deepak Narayan, MD, John. A. Persing, MD* Section of Plastic Surgery, 330, Cedar Street, Boardman Building-330, New Haven, CT 06520, USA
This article highlights the technical details of the authors’ techniques in the surgical management of craniosynostosis. The role of orthotic devices vis-a vis positional plagiocephaly and postsurgical molding is discussed. A method of avoiding temporal hollowing in cranioplasty is presented. This article focuses on various technical aspects of pediatric craniofacial surgery that we have used in practice to optimize the cosmetic quality of the outcome. Craniosynostosis surgery The correction of premature sutural closure is performed primarily for two reasons: normalization of the skull deformity and reduction of intracranial pressure. Renier [1] and Thompson et al [2]. The procedure adopted depends on the suture that is fused, the age of the patient, and the associated anomalies present. Highlights of the techniques used for the various forms of craniosynostosis in our practice are presented below. Sagittal synostosis Sagittal synostosis remains the most commonly encountered form of craniosynostosis. The simplest form of surgical treatment for this disorder is the strip or linear craniectomy, where the prematurely fused suture is excised in the hope that once the restrictive force is released, the brain will expand and the skull will then mold itself into a more normal shape. In terms of the degree of correction obtained, the results of this procedure are * Corresponding author. E-mail address: [email protected] (J.A. Persing).
suboptimal compared with those of the more comprehensive cranioplasty procedures [3]. There may still be a place for the strip craniectomy, however, in the mild and early forms of sagittal synostosis. The procedure’s primary appeal rests on its simplicity and, in some cases, effectiveness, particularly if coupled with a skull molding cap. The advantages of this approach lie in the smaller scar and potentially lesser blood loss, which have to be balanced against a less complete correction and the need for prolonged (approximately 1 year) use of a skull molding cap. For most cases of more advanced sagittal synostosis, the cardinal features of our cranioplasty technique are (1) release of sutural stenosis, (2) remodeling of cranial bone, (3) active reduction of the abnormally long dimension of the skull, and (4) active expansion of abnormally narrow areas [4]. The technique we currently favor in children less than 1 year of age is a modification of the p procedure originally described by Jane and Persing [4]. The patient is placed in a modified prone position [5], which allows easy access to the anterior and posterior skull. A frontal craniotomy is performed with the cephalad osteotomy posterior to the hairline, followed by separate parietal and parieto-occipital osteotomies. The squamous part of the temporal bone is out-fractured along with the overlying temporalis. The frontal and occipital bossing is reduced by radial osteotomies, and the parietal bone is remodeled in a similar fashion to produce a more convex form. The anteroposterior (AP) dimensions are reduced by 1 to 1.5 cm by removal of a segment of bone in the midline, and the frontal bone is attached to the supraorbital rim with removal of triangular wedges of bone laterally to allow posterior tilting of the forehead (Fig. 1).
1042-3680/02/$ - see front matter Ó 2002, Elsevier Science (USA). All rights reserved. PII: S 1 0 4 2 - 3 6 8 0 ( 0 2 ) 0 0 0 2 2 - 0
506
D. Narayan, J.A. Persing / Neurosurg Clin N Am 13 (2002) 505–513
Fig. 1. Sagittal synostosis: operative detail. (Top panel) (1) Frontal craniotomy and osteotomy, (2) parietal osteotomy, (3) occipital osteotomy, and (4) temporal bone out-fracture. (Lower panel) Fixation of radially osteotomized segments and reduction of anteroposterior diameter. Note removal of triangular wedge of bone. (Modified from Cohen MM, MacLean RE, editors. Craniosynostosis—diagnosis, evaluation and management. 2nd edition. New York: Oxford University Press; 2000:215; with permission.)
The ‘‘brittleness’’ of the bones in children older than 1 year of age prevents remodeling as described previously. In such instances, we have modified the approach described by Marchac and Renier [6], wherein serial osteotomies are performed anteriorly to posteriorly, with the most basal frontal osteotomy being performed at the height of the forehead, followed by serial posterior frontoparietal and parieto-occipital osteotomies (Fig. 2) [4], with a reversal of the midparietal and posterior frontal bone if required. Kerfs (Fig. 3) are placed on the inner surface of the bone seg-
Fig. 2. Sagittal synostosis (late treatment). (From Cohen MM, MacLean RE, editors. Craniosynostosis— diagnosis, evaluation and management. 2nd edition. New York: Oxford University Press; 2000:215; with permission.)
ments to allow for remodeling. Although the illustrations depict the use of sutures (wires), we now use absorbable plating systems, which are particularly useful in decreasing the length of the skull and achieving a wider biparietal diameter. Metopic synostosis The metopic suture is the first to fuse in the normal calvarium. Premature fusion of the metopic
D. Narayan, J.A. Persing / Neurosurg Clin N Am 13 (2002) 505–513
507
Fig. 3. Placement of kerfs. (From Persing JA, Edgerton MT, Jane JA, editors. Scientific foundations and surgical treatment of craniosynostosis. Baltimore: Williams & Wilkins; 1989:164–5; with permission.)
suture results in trigonocephaly and hypotelorism. The three anatomic features that mark this condition are deficiency of the projection of the lateral orbital rims, recession of the lateral frontal bone, and narrowing of the squamous part of the temporal bone. Because a wide range of acceptable appearances may result from this process, operative intervention requires careful judgment. A prominent metopic ridge, for instance, in the absence of the other hallmarks of metopic synostosis can merely be burred down to restore a normal contour. Our approach to more evident trigonocephaly involves bilateral orbital rim osteotomies as well as a bifrontal osteotomy performed to the level of the hairline (Fig. 4). Temporalis myo-osseous flaps are raised, and these are advanced to support the repositioned orbital rims and provide more fullness in the temporal squamous area. The bifrontal graft is remodeled using radial osteotomies and Tessier rib benders.
Coronal synostosis Coronal synostosis may present with unilateral or bilateral fusion of the sutures. The clinical features of unilateral coronal synostosis are distinct from the bilateral form and are described individually, because each of these features needs to be addressed separately. In unilateral coronal synostosis, on the side of the fused coronal suture:
1. The frontal and parietal bones are flattened. 2. The orbital rim is recessed, and the mediolateral width of the orbit is smaller than the opposite side. 3. The temporal squamous bone is protuberant. 4. The ear is anteriorly displaced. 5. The contralateral frontal bone is unduly prominent. 6. The orbital rim is depressed inferiorly compared with the orbital rim on the fused side. Additional findings include mandibular asymmetry (mandibular midline deviated to the side opposite the synostosis) and deviation of the nasal radix to the ipsilateral side. These are usually minor and rarely require surgical correction. Surgical correction involves performing a coronal incision in the supraperiosteal plane to the orbital rims, at which level the dissection is continued in a subperiosteal plane intraorbitally. The patent coronal suture at the fontanelle on the contralateral side is used as access for a craniotomy. A bifrontoparietal craniotomy with radial osteotomies is performed in children less than 1 year of age. In children 1 year of age or older, the deformed frontal bone on the affected side may be replaced by parietal bone graft harvested by a separate biparietal osteotomy, followed by trimming of the greater wing of the sphenoid on the side of the affected suture. The orbital rims are reshaped with burrs to attain a normal form. Internal support for the newly fashioned orbital rim is provided for by a
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Fig. 4. Metopic synostosis. (Top panel) Frontoparietal osteotomy and burring down of metopic prominence. (Lower panel) Fixation to orbital rim. (From Persing JA, Edgerton MT, Jane JA, editors. Scientific foundations and surgical treatment of craniosynostosis. Baltimore: Williams & Wilkins; 1989:164–5; with permission.)
separate bone graft—the bowstring procedure. The composite temporalis myo-osseous flap (see below) is used to prevent temporal hollowing after the orbital rims are attached to the midline and laterally at the frontozygomatic suture (Fig. 5). Molding of bone in older children is done using kerfs on the endocranial surface of the skull. In patients with localized residual defects or in patients who are not desirous of extensive surgery, we have used methylmethacrylate or a bone paste to reconstruct the defects. Bilateral coronal synostosis The turricephalic skull resulting from bilateral coronal synostosis can present in either a nonsyndromic or syndromic form, where it may be associated with craniofacial syndromes such as
Apert’s, Crouzon’s, or Pfeiffer’s. A modified prone position is used to provide simultaneous access to the anterior and posterior skull. Cervical spine films and, in the case of craniofacial syndromes, MRI are obtained to determine cervical spine instability and the presence of an Arnold-Chiari malformation, respectively. The presence of these conditions dictates the use of a staged cranioplasty technique. The key features of the one-stage operative procedure are illustrated in Fig. 6. A bifrontal craniotomy is performed at the level of the forehead. A disk of bone is left attached to the vertex of the skull with two parietal struts as shown. Separate parietal craniotomies are also carried out. Occipital barrel stave osteotomies are performed and out-fractured to increase the AP dimensions. The orbital rims are replaced after contouring with the temporal flap,
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Fig. 5. Coronal synostosis. (Top panel) Frontoparietal osteotomy. (Middle panel) Radial osteotomy and remolding. (Lower panel) Fixation of osteotomized fragments. (From Persing JA, Edgerton MT, Jane JA, editors. Scientific foundations and surgical treatment of craniosynostosis. Baltimore: Williams & Wilkins; 1989:164–5; with permission.)
holding it in position. The height of the skull is reduced between 1 and 2 cm depending on the correction required by cinching the basal and parietal bones together (see Fig. 6, lower panel), and forehead projection is reduced by posterior migration/ movement of parietal struts.
Prevention of temporal hollowing Orbital rim advancement in coronal and metopic synostosis, although enhancing periorbital esthetics, commonly creates an unattractive temporal depression. Various methods are used
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temporal hollowing based on the creation of a temporalis myo-osseous flap [7]. A brief description of our technique is given below (Fig. 7). A burr hole is placed superior to the superior temporal line, giving access to the epidural space, and a bifrontal craniotomy is performed. The temporalis muscle is then minimally dissected off the posterior portion of the zygomatic process of the frontal bone (0.5–1 cm) to allow access to osteotomize the lateral orbital roof. With epidural dissection and the orbital rim removal completed, the most posterior aspect of the temporalis muscle is divided. The division is done in line with the orientation of the muscle fibers superior and posterior to the pinna. A vertical osteotomy is performed anterior to this line. One limb of a Gigli’s wire saw or Midas Rex bit is placed in the osteotomy site in the posterior squamous portion of the temporal bone. Another is placed in the osteotomy site in the region of the pterion. The squamous temporal bone and its overlying temporalis muscle are elevated out of the temporal fossa with a saw cut of the squamous temporal bone, yielding a myoosseous flap. The temporal fossa is then cleared of the remaining temporalis muscle, and the superior portion of the greater wing of the sphenoid is trimmed for easier inset of the flap. For patients with metopic synostosis, the remaining basolateral sphenoid wing is split sagittally. Barrel stave osteotomies and lateral fractures of the temporal and lateral sphenoid bones are performed to increase projection locally. In coronal synostosis, the posterior bone segments undergo in-fracture to decrease projection. Fig. 6. Bilateral coronal synostosis. A biparieto-occipital bone graft is developed posteriorly with a bone bridge between the two hemicrania located below the level of the torcula. The remaining occipital bone undergoes barrel stave osteotomy. (From Cohen MM, MacLean RE, editors. Craniosynostosis—diagnosis, evaluation and management. 2nd edition. New York: Oxford University Press; 2000:215; with permission.)
to counteract this deformity, including filling the hollow with bone chips and posterior detachment of the temporalis muscle to rotate it anteriorly either unfolded or folded over itself to add additional bulk to obliterate the hollow. Although these techniques may prevent hollowing to some degree initially, the long-term results are unsatisfactory. We have described a technical innovation that provides a reliable method for the prevention of
Lambdoid synostosis The increased incidence of deformational plagiocephaly (see below) has caused considerable confusion in the diagnosis of lambdoid synostosis. Typically, unilateral lambdoid synostosis is characterized by a flattening of the ipsilateral parietal occiput asymmetry at the base of the skull and posterior and inferior displacement of the ipsilateral ear. Radiologically, a deviation of the foramen magnum to the affected side and premature fusion of the lambdoid suture are demonstrable. Rarely, it may mimic the deformational plagiocephaly skull pattern but differs in that it is progressive and nonremitting despite conservative methods, such as physical therapy and skull molding helmet use. The parieto-occiput is removed as a single unit with a coronal suture, providing access. The major
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Fig. 7. Prevention of temporal hollowing. (1) Burr hole made at superior temporal line, (2) bifrontal craniotomy is performed, (3) temporalis fascia is detached from posterolateral orbital rim, (4) orbital rim is elevated and advanced, (5) osteotomy in the greater wing of the sphenoid is deepened in the sagittal plane with a sagittal saw, (6) temporalis muscle fibers are divided in a plane parallel to their orientation, (7) osteotomy of squamous part of temporal bone is performed, (8) Gigli saw osteotomy preserves temporalis attachment to bone, (9) musculo-osseous flap is reflected laterally, (10) 2–3 mm of squamous temporal bone is removed by rongeur to allow anterior rotation of bone without overlap, (11) barrel staves are fractured laterally in the anterior squamous temporal region and medially in the posterior region (in coronal synostosis), (12) musculo-osseous flap is attached anteriorly, (13) musculo-osseous flap is attached to the advanced orbital rim, and (14) musculo-osseous flap is attached to the reshaped frontal bone. (From Cohen MM, MacLean RE, editors. Craniosynostosis—diagnosis, evaluation and management. 2nd edition. New York: Oxford University Press; 2000:215; with permission.)
venous structures, such as the torcula and sagittal and transverse sinuses, make this a particularly tedious dissection. Radial osteotomies are performed on the piece removed, whereas barrel stave osteotomies are performed on the calvarium basal to the parieto-occiput. Contralateral to the fused suture, the staves are fractured inward, whereas, ipsilaterally, they are fractured outward. Bilateral lambdoid synostosis is vanishingly rare in isolation from craniofacial syndromes.
Correction of positional molding Positional or deformational plagiocephaly is a term that is applied to an abnormal head shape in an infant that develops as a result of positional molding of the cranium unrelated to premature sutural fusion. A variety of factors have been implicated in the development of this deformity, including a restrictive intrauterine environment, birth trauma, torticollis, cervical anomalies,
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sleepingposition, lackof full mineralization, neurologic factors, or a combination of these factors [8]. In 1992, the American Academy of Pediatrics [9] issued a recommendation that infants be positioned to sleep either on their back or sides to reduce the risk of sudden infant death syndrome (SIDS). Subsequently, multiple centers noted an increase in craniofacial deformities of nonsynostotic origin, although this had a beneficial effect in reducing the number of deaths related to SIDS. Supine positioning is to be condemned, but frequent position changes in the earliest stages of life may reduce the likelihood of skull deformities. Appropriate management of positional deformities, once formed, include simple repositioning of the infant, avoidance of prolonged periods of rest in one position, exercises to increase the range of movement of the neck, and the use of orthotic devices. Planned cranial deformation has been used for centuries by various cultures. Literature describing the therapeutic effect of orthotic devices is available [8,10,11]; however, a criticism leveled against published studies is that they lack appropriate controls. In other words, it is not known whether simple repositioning and exercising of the infant alone can produce the results achieved with the use of orthotic devices. The general impression is that properly designed and applied devices are more effective and rapid in reducing skull deformities, however. Potential risks to health associated with this type of device include (1) skin irritation, breakdown, and subsequent infection; (2) head and neck trauma caused by alteration of the functional center of the mass of the head; (3) impairment of brain growth and development from mechanical restriction of cranial growth; (4) eye trauma caused by mechanical failure or poor fit; and (5) contact dermatitis [12]. We believe that helmets have a role, particularly in the severely deformed skull, in patients who have the condition when exercises are either ineffective or not followed, in patients with gastric reflux precluding prone positioning even while supervised, and in older infants ([9 months of age) and those with significant facial deformity.
Resorbable materials The use of resorbable plates in the fixation of the craniofacial skeleton represents a major advance in the field, particularly in the pediatric
age group. The advantages are inherent in the biodegradability of the product. Concerns about long-term visibility of the plates in thin skinned individuals, malpositioned implants, or the effects of intracranial migration are mitigated. The plates are generally thicker than their metal counterparts and are therefore more easily palpable in the early postoperative stages. A representative series describing the use of bioresorbable fixation in pediatric craniofacial surgery is that described by Kurpad et al [13]. The first bioabsorbable fixation system for the craniofacial skeleton approved by the US Food and Drug Administration was the Lorenz Lactosorb system (Walter Lorenz, Jacksonville, FL) [14–16]. The material used, Lactosorb, is a copolymer of L-lactic acid (which is slowly absorbed, thus providing strength) and glycolic acid (which is rapidly absorbed) at a ratio of 82:18. This, being substantially amorphous, has marked advantages in terms of long-term stability and degradation compared with implants made of the pure forms of its component chemicals. Clinical complications, such as pronounced fibrous encapsulation, sterile abscess and sinus formation, and bone osteolysis, have been reported for the homopolymers. One of the few studies showing a reaction to a copolymer (sinus formation) involved polyglactin 910, a copolymer with an almost inverse ratio of polylactic acid and polygalactic acid compared with Lactosorb. In vivo, the material has been histologically demonstrated to be eliminated by approximately 1 year. Implants of another bioabsorbable product, MacroPore (Macropore Biosurgery, San Diego, CA), are manufactured from medical grade 100% amorphous 70:30 poly(Llactide-co-D,L-lactide). This is produced from a mixture of 70% L-lactide and 30% DL-lactide, which retains approximately 70% of its initial strength after 9 months and approximately 50% after 12 months, converts into carbon dioxide and water by the process of bulk hydrolysis, and resorbs completely in approximately 18 to 36 months. The use of bioabsorbable materials has now extended to the construction of distraction devices. Cohen and Holmes [17] describe their experience with biodegradable mesh Macropore as a substitution for metallic fixation plates. In discussing distraction in a 4-year-old with Crouzon’s syndrome, the clinical results achieved by this device are equivalent to those achieved by the metal counterpart with the added advantage of permitting internal distraction without the need for complete removal of the fixation device.
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Our experience with distraction devices for midface advancement has been favorable to date. We have obtained 30 mm of midface advancement using these devices.
[8]
[9]
References [1] Renier D. Intracranial pressure in craniosynostosis: pre and postoperative recordings—correlation with functional results. In: Persing J, Edgerton M, Jane J, editors. Scientific foundations and surgical treatment of craniosynostosis. Baltimore: Williams & Wilkins; 1989. p. 263–9. [2] Thompson DNP, Malcom GP, Jones BM, et al. Intracranial pressure in single suture craniosynostosis. Pediatr Neurosurg 1995;22:235–40. [3] Panchal J, Marsh JL, Park TS, et al. Sagittal craniosynostosis outcome assessment for two methods and timings of intervention. Plast Reconstr Surg 1999;103:1574–84. [4] Jane JA, Persing J. Neurosurgical treatment of craniosynostosis. In: Cohen MM, MacLean RE, editors. Craniosynostosis—diagnosis, evaluation and management. New York: Oxford University Press; 2000. p. 209–27. [5] Park TS, Haworth CS, Jane JA, et al. Modified prone position for cranial remodeling in children with craniofacial dysmorphism. Neurosurgery 1985;16: 212–4. [6] Marchac D, Renier M. Craniofacial surgery in craniosynostosis. Boston: Little Brown & Company; 1982. [7] Persing JA, Mayer PL, Spinelli HM, et al. Prevention of temporal hollowing after fronto orbital
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advancement for craniosynostosis. J Craniofac Surg 1994;5:271–4. Ripley CE, Pomatto J, Beals SP, et al. Treatment of positional plagiocephaly with dynamic orthotic cranioplasty. J Craniofac Surg 1994;5:150–9. Anonymous. American Academy of Pediatrics task force on infant positioning and SIDS. Pediatrics 1992;89:1120–6. Kelly KM, Littlefield TR, Pomatto JK, et al. Importance of early recognition and treatment of deformational plagiocephaly with orthotic cranioplasty: cleft palate. Craniofac J 1997;36:127–30. Kelly KM, Littlefield TR, Pomatto JK, et al. Cranial growth unrestricted during treatment of deformational plagiocephaly. Pediatr Neurosurg 1999;30: 193–9. Federal Register, vol. 63, no. 146. 21CFR, part 882, July 1998. Kurpad SN, Goldstein JA, Cohen AR. Bioresorbable fixation for congenital pediatric craniofacial surgery. Pediatr Neurosurg 2000;33:306–10. Pietrzak WS, Verstynen ML, Sarver DR. Bioabsorbable fixation devices: status for the craniomaxillofacial surgeon. J Craniofac Surg 1997;8:92–6. Pietrzak WS. Critical concepts of absorbable internal fixation. J Craniofac Surg 2000;11:335–41. Rubin PJ, Yaremchuk MJ. Complications and toxicities of implantable biomaterials used in facial reconstructive and aesthetic surgery. A comprehensive review of the literature. Plast Reconstr Surg 1997;100:1336–53. Cohen SR, Holmes RE. Internal LeFort III distraction with biodegradable devices. J Craniofac Surg 2001;12:264–72.