Fig. 40.1
Preparation for transcranial orbital osteotomy . (a) The coronal incision to the upper face involves a stair-step incision preceded by blocking suture placement to minimize blood loss. The plane of dissection is above the temporalis muscle and between the galea and periosteum. (b) At the level of the supraorbital rims, the plane of dissection goes from subgaleal to subperiosteal at which point the upper orbits may be degloved, providing wide exposure to this region. In preparation for a craniotomy, the temporalis muscle is reflected out of its temporal fossa. (c, d) Following burr hole placement, the frontal bone flap is removed. The frontal lobes are reflected from the anterior cranial fossa in an extradural plane, providing access to the orbital roof, nasoethmoid region, and medial and lateral orbital walls. (e) A burr hole in the temporal region provides access for clearing of the middle cranial fossa to facilitate transcranial orbital osteotomy
Once the coronal incision is made, the coronal flap is turned forward. At the superior orbital rim region, the subperiosteal plane is entered and further dissection performed. The dissection is carried over the rim into the orbit, and in this plane a complete superior orbital degloving is performed (Fig. 40.1b). The lateral canthal attachment and the lateral canthal soft tissue mass should be identified and a suture placed for fixation at the termination of the procedure. Both temporal muscles are dissected in a subtemporal plane out of their respective temporal fossae. At this point in the operation, the neurosurgeon performs a unilateral or bifrontal craniotomy with a clearing of the anterior cranial fossa and middle fossa to allow the brain to be safely retracted and the orbital osteotomies completed (Fig. 40.1c, d). Great care must be taken in the midline to avoid tearing of the dura in the cribriform area. Frequently, access to the middle cranial fossa requires a temporal burr hole to facilitate dissection (Figure 40.1e).
If exposure to the inferior orbit is required, either a transconjunctival approach with a lateral canthotomy or a subciliary incision can be made. These incisions, described elsewhere in this text (see Chap. 38), are carried down to the inferior orbital rim where the periosteum is incised and a subperiosteal orbital floor dissection is completed. The dissection will link laterally with the dissection from above. Medially, care must be taken to avoid injury to the medial canthal tendon and nasolacrimal system. Most often, surgery of the medial orbit can be accomplished by osteotomy of the canthal bearing segment of the bone and appropriate repositioning. If this cannot be performed, the medial canthal tendon should be disinserted from its attachment for later reattachment with a transnasal suspension wire. However, this should be avoided, if at all possible, due to the intricate detail and aesthetics of this region. In such circumstances, although we do not routinely prophylactically intubate the nasal lacrimal system, this can be considered.
Once the surgical procedures are completed, the wound is closed. The lateral canthus is resuspended through small drill holes in the lateral orbital rim. The temporalis muscle is resuspended with a combination of sutures to small drill holes in the bone or to wires or plates. Closure of the subciliary wound can be performed with a single running nonabsorbable suture or fine interrupted dissolving sutures. The coronal incision is typically closed with a deep suture to the galea and a fast-absorbing plain gut suture to the skin.
During procedures on the superior orbit, it is almost always necessary to cut and remove the bone. As mentioned previously, the bone can be safely removed en bloc and then manipulated ex vivo. Manipulation of the bone is frequently done by a partial osteotomy and bending with reinforcement with wires or small microplates [19, 20] (Fig. 40.2). In those instances in which the bone must be removed for pathological conditions, bone grafts are necessary. In the young patient, the bone can frequently be partially osteotomized and bent, while in the older patients, this may not be possible and a complete osteotomy is required. Following replacement, the manipulated bones or bone grafts are fixed in position. Most often, this takes the form of wire suture with micro- and miniplates reserved for those situations where structural stability dictates otherwise. In the infant patient, such wires and plates may passively translocate to an intracranial position with growth [21]. We have seen no instances of problems from these [22], but in children below the age of 8–10, we prefer resorbable suture and absorbable plates and screws. In older patients, titanium plates and screws can be used without these considerations.
Fig. 40.2
Bone bending . The osteotomized segment can be manipulated ex vivo by creating small kerf cuts on the inner surface (see inset). This allows forceful bending held in position by wires or suture as illustrated also in the inset. In the very young patient, bony bending can frequently be performed without partial osteotomy using specialized bone bending forceps
If bone grafts are required, they can come from several sources. In the patient less than 1 year of age, strips of bone can be taken from the posterior aspect of the frontal bone flap. Infants of this age generally always regenerate this bone gap from the underlying dura. In the older child and adult, when this does not occur, alternative bone sources must be used. Cranial bone can be taken, harvested as strips from the posterior outer calvarial surface using a combination of burrs and osteotomes (Fig. 40.3a–d). Alternatively, the frontal bone flap can be split with the bone taken from the inner surface to preserve the integrity and contour of the outer cortex (Fig. 40.3e). Bone grafts from the cranial region are preferred, because they have an improved survival when used in the craniofacial region, involve no additional operative sites, and are associated with little morbidity if done properly [23, 24]. However, when additional bone is needed, rib or iliac bone can be utilized.
Fig. 40.3
Bone harvesting . (a) The initial stage in cranial bone harvest for the outer cortical surface involves cutting a series of parallel channels through the cortical bone into the diploic space. (b, c) After the initial channels are cut, a contouring burr (b) is used to bevel the edge of the bone to allow insertion of a straight osteotome (c). (d)The osteotome and mallet can then be used to harvest uniform strips of outer cortical bone. (e) An alternative method when a craniotomy has been completed is to use the oscillating saw and osteotomes to split inner from outer cortex. This allows the bone flap to be replaced without any visible deformity and provides a large source of bone
Bone substitutes are a controversial area. Although a great deal of effort is now underway to develop good bone substitutes and bioceramics, at present autogenous bone remains the material of choice [24]. Alloplastic materials in general should be avoided. The increased risk of infection when operating near the paranasal sinuses, the long-term effects of alloplasts, and their lack growth potential all argue against their use.
There are other approaches to the craniofacial skeleton. The ophthalmologist is not likely to be involved in these cases but should be familiar with them. The midface is frequently approached by a combination of intraoral upper buccal sulcus incisions with or without midfacial degloving (Fig. 40.4) and the standard lower lid incision. The lower face or mandible can be approached with a combination of intraoral lower buccal sulcus incisions and strategically placed cervical incisions.
Fig. 40.4
Midface exposure. In addition to transpalpebral incisions, midface exposure is facilitated by the gingival buccal incision. After first incising the mucosa (a) a subperiosteal dissection can be used to expose the alveolus, the nose, and the lower malar midface structures (b)
The Management of Specific Craniofacial Disorders
Rare Craniofacial Clefts
Although the rare craniofacial clefts were initially classified into centric and acentric [10], the experience of Tessier [25, 26] dictated a separate approach. Based on his clinical experience, the orbit is used as a center of reference along with the midline, and clefts radiating around the orbit are numbered based on their position (Fig. 40.5). A horizontal line drawn through the mid-axis of the orbit separates facial clefts below from orbital clefts above. Typically, a cleft that involves both the face and cranium is a craniofacial cleft. These clefts are numbered from 1 to 14, and it is usual for combination clefts to add to a total of 14 (i.e., cranial cleft 10 is usually associated with facial cleft 4). It should be stressed that the clefts may present as true through and through clefts of both bone and soft tissues or may be represented merely by furrows in each. Additionally, clefts in the medial region may be associated with either tissue deficiency or tissue excess [26]. Facial clefts are not usually associated with genetic transmission, with the exception of the Treacher Collins syndrome (mandibulofacial dysostosis), which can be considered a true clefting phenomenon.
Fig. 40.5
The Tessier classification of rare craniofacial clefts. As mentioned in the text, a horizontal line drawn through the mid-axis of the orbits separates facial clefts below from orbital clefts above with a numbering system beginning in the midline and progressing counter-clockwise around the orbit like the spokes of a wheel. (a) Soft tissue cleft positions. (b) Bony cleft positions
The principles in the management of these clefts are not dissimilar to those of the management of the more common cleft of the lip and palate. The bony deformity is addressed by appropriate osteotomy and repositioning of segments, with or without the addition of bone grafts, while the soft tissue is managed by a combination of mucosal flaps for lining and skin flaps for skin closure [25–29]. In each of the latter cases, this is accomplished by the use of local rotation flaps, Z-plasties, or the like (Fig. 40.6). These maneuvers reposition malpositioned structures such as the lips, eyelids, and brows to their normal position. The median and paramedian clefts may be associated with hypertelorism and are discussed separately. It is beyond the scope of this discussion to give examples of each type of Tessier cleft, but specific examples are included in Fig. 40.7. Although surgery for these disorders is frequently done in infancy and early childhood, disruption of the growth matrix by the clefting process and by surgery necessitates frequent review of the condition with adjunctive procedures undertaken as required.
Fig. 40.6
Repair of Tessier #4 cleft. (a) Multiple Z-plasties are designed to increase vertical length and to fill the defect with skin–muscle flaps. In this instance, three Z-plasties are utilized. (b) Flap A is really a transposition-type flap, which also raises the medial canthal angle. The alar base is rotated down with flaps B and C transposed. Flaps D and E complete the third Z-plasty, assisting in lip reconstruction. The cleft lip is repaired much like an eyelid coloboma by excising the edges and carefully matching the appropriate anatomic landmarks on each side
Fig. 40.7
Examples of rare craniofacial clefts. (a) Tessier No. 0 cleft; (b) bilateral Tessier No. 3–11 clefts; (c) left-sided Tessier No. 3–11 or 4–10 cleft; (d) left-sided Tessier No. 4 or 5 cleft and right-sided Tessier No. 7 cleft
As one might imagine, any clefting phenomenon that involves the orbit may lead to a significant disruption of the ocular adnexa. Clefts in or near the medial canthus may lead to medial canthal dystopia in either a horizontal or vertical dimension. Also, lateral canthal abnormalities of position may be seen. Since the nasolacrimal system occupies a key position in the medial facial region, disruption of this structure by clefts of this region is common. For these severe canthal dystopias, refixation by separation of the canthal tendon from bone and wiring may be in order. Alternatively, segmental osteotomy of the medial orbital wall with the canthal attachment intact may be undertaken. The nasolacrimal system can be addressed by any of the current techniques available, including intubation and stenting or complete reconstruction. This topic is covered elsewhere (see Chaps. 26, 27, 28, 29, and 30).
Treacher Collins Syndrome
Treacher Collins syndrome , or mandibulofacial dysostosis [30, 31], is justifiably classified as a syndrome involving clefts 6, 7, and 8 of the Tessier system. This condition affects 1 in 50,000 live births is inherited as an autosomal-dominant disorder with variable penetrance often involving genetic mutations in, but not limited to TCOF1, POLR1D, and POLR1C [32, 33]. Manifestations of this disorder involve both the bone and soft tissue. Bony deformities (Fig. 40.8) are characterized by poorly developed or deficient inferior and lateral orbital rims, frequently with a bony cleft and absent or hypoplastic zygomas. The maxilla and mandible typically are vertically deficient posteriorly with a resultant anterior deficiency and open bite deformity. In concert with this bony deficiency, the ocular adnexa are characterized by downward sloping of the palpebral fissure and inferior displacement of the lateral canthus with colobomata and pseudocolobomata of the lids and malar midface soft tissue deficiency (Fig. 40.9). Patients typically have ear deformities, varying from complete microtia to a minimally deformed pinna [34].
Fig. 40.8
Treacher Collins syndrome . (a) Schematic representation of the bony deformity of mandibulofacial dysostosis (Treacher Collins syndrome). Note the absent zygomatic arch and malar eminence, absence of the lateral orbital wall, hypoplastic posterior mandible, and anterior open bite deformity. (b) Three-dimensional image of patient with Treacher Collins syndrome showing anatomy similar to that of Fig. 40.8a
Fig. 40.9
The typical appearance of the patient with Treacher Collins syndrome. (a) Lateral facial clefts or soft tissue deficiency that overlies hypoplastic malar bones. Also shown are the downsloping palpebral fissures with pseudo-colobomata of the lower eyelids; (b) a diminutive mandible and microtia are also present
Principles in the management of this condition involve both the bony and soft tissue deformity. Although, conceptually, Treacher Collins syndrome seems easy to manage, the soft tissue deficiencies make the results of therapy disappointing in many circumstances. For the bony deficiency, bone grafts to the lateral orbit and malar midface area via a transcoronal extracranial approach are appropriate [35] (Fig. 40.10). The soft tissue deficiency, however, contributes to a high rate of resorption for these bone grafts, and they frequently need to be repeated. Vascularized cranial bone grafts have been utilized with some improved success [36], but the extra time and effort involved in their harvest and their limitations of position make them infrequently the first choice. Our experience dictates that initial bone grafting may best be followed in adolescence by repeat bone grafting or by the use of synthetics (e.g., silicone elastomer, polytetrafluorethylene) to augment the malar region once basal bone continuity is established.
Fig. 40.10
Schematic of bony reconstruction of the malar orbitozygomatic complex in Treacher Collins syndrome. Bone grafts are placed to recapitulate the normal zygomatic eminence, arch, and lateral orbital walls
The soft tissue deficiencies and malpositions demand special expertise. These techniques are described elsewhere in this text and consist of lateral canthopexy, Z-plasty of the coloboma, cheek flap advancement, and upper lid to lower lid pennant switch or transposition flaps [37]. They are frequently performed as secondary procedures by the oculoplastic surgeon once the initial bony correction has been completed (see Chap. 21).
The lower face deformities also demand attention. A combination of maxillary and midface osteotomies to level and advance the occlusion is required in the most severe cases. In the less mildly affected patient, a combination of orthodontic correction and advancement genioplasty may be all that are required. The technique of distraction osteogenesis of the mandible [38], in which the mandible is cut and gradually elongated as new bone forms, has proven application to the child of intermediate age with a moderate to severe deformity (Fig. 40.11) [39].
Fig. 40.11
Distraction osteogenesis . Management of the hypoplastic mandible in Treacher Collins syndrome by distraction osteogenesis. (a, b) Preoperative views. (c) Intraoperative view demonstrating distractor prior to placement. (d) Following distractor placement through a transoral approach. The distractor activator exits through the skin inframandibular position. (e) A-P cephalogram of the skull before distraction is initiated. (f) Following activation of the distractor, lengthening of the posterior mandible is observed. (g) Postoperative view of the patient showing significant elongation of the posterior mandible
Craniosynostosis
Craniosynostosis occurs when one or more cranial vault or cranial base sutures undergo premature fusion [40, 41]. The function of a suture is to allow passive expansion of the skull and face during growth of the brain, eye, facial muscles, teeth, and sinuses. These seams allow passive growth to go unimpeded. In general, once growth is complete, sutures may fuse and become nonfunctional [42]. This occurs at a variable time in life for each suture, the earliest suture to fuse being the metopic suture, which fuses at approximately age 7 months. If these sutures close prematurely, brain, orbital, or midface growth is prevented. Virchow first noted that skull deformities are caused not only by an inhibition of growth at right angles to the prematurely closed suture but by compensatory growth in the cranium where sutures remain patient [40].
The craniosynostoses are broken down into two broad categories, the syndromic and nonsyndromic groups. Syndromic synostoses are those in which one or more cranial vault and base closures are associated with other dysmorphic features. The most common syndromic synostoses include Apert syndrome, Crouzon syndrome, Pfeiffer syndrome, and Saethre–Chotzen syndrome.
In addition to the syndromic synostoses, there is a large group of nonsyndromic premature suture closures. These are classified based on the resultant skull shape after the premature suture closure occurs.
The first attempts at correction of these deformities were made over 100 years ago when linear craniectomies or removal of the synostosed suture was performed [43, 44]. Although this allowed room for subsequent brain growth, the sutures frequently resynostosed and deformity recurred. Additionally, such simple synostectomies did not improve an already established facial deformity [4]. In 1967 Paul Tessier described his technique for a transcranial approach to the orbit, midface, and vault by osteotomy and repositioning in the treatment of these deformities [1, 2]. A wide variety of technical refinements occurred over the subsequent decades. The most frequent reason for referral to the craniofacial team is dysmorphic craniofacial appearance in an infant or young child. The need for surgery and the timing of surgery for craniofacial dysostosis is based in part on optimizing the cosmetic goals of the proposed surgery and in part on concern that premature closure of the cranial sutures may constrict brain growth [45]. The volume of the brain nearly triples in the first year of life [46], and brain growth continues until about 8 years of age when the sutures normally begin to close. If multiple sutures are closed before brain growth is complete, the result may be mental retardation, headaches, papilledema, and optic atrophy. Ideally, cranial decompressive surgery is done very early in life, when the facial bones are soft and the cosmetic goals of surgery cannot yet be fully achieved. It is the task of the neurosurgeon on the craniofacial team to assess the need for early surgery, even if this commits the child to multiple procedures.
Patients with single-suture craniosynostosis are generally believed not to suffer brain constriction, regardless of the severity of the deformity, except in a minority of patients. Thus, timing of surgery for isolated sagittal, lambdoid, metopic, and unilateral coronal synostosis is usually determined by cosmetic goals alone. This concept has been challenged. Patients with single-suture synostosis have been studied using invasive intracranial pressure (ICP) monitoring, and ICP was found to be elevated in 8% of children with unilateral coronal synostosis, 25% of children with sagittal synostosis, and 33% of patients with metopic synostosis [47]. This may reflect the difficulty in determining which sutures are functionally closed, since cases of presumed unisutural craniosynostosis may actually have multiple closed sutures. In most cases, sagittal and coronal synostoses are surgically treated before 1 year of age anyway, and elevated ICP is rarely a concern. Syndromic craniofacial dysostosis such as Crouzon syndrome and Apert syndrome are often associated with premature closure of multiple sutures, and there is concern that brain constriction may occur without early surgery. Even in the absence of overt signs and symptoms of intracranial hypertension, the theoretical possibility exists that foreshortening of the anterior cranium may cause underdevelopment of the frontal lobes resulting in neuropsychological problems. Apert syndrome and to a lesser extent Crouzon syndrome are associated with mental deficiency, but it is unclear to what extent this is due to brain constriction or multifactorial genetic factors.
Surprisingly, few data are available to relate ICP to craniofacial syndromes, but the number of patients experiencing elevated ICP may be greater than initially presumed [48]. Marchac and colleagues reported that 20% of children with craniosynostosis have elevated ICP as determined by monitoring [49]. They recommend that frontal suture release be carried out for brachycephaly at age 2–4 months, with formal orbitofrontal advancement at a later stage.
For most other craniofacial syndromes, including plagiocephaly, surgery can be delayed until age 6–12 months [50]. The cloverleaf deformity (Kleeblattschädel) is a special case. This clinical picture of trilobar skull triphyllocephaly arises from either Crouzon or Apert syndromes and implies pancraniosynostosis with severe brain constriction. Surgery is undertaken in early infancy and consists of removal of most of the cranial vault in one or two stages [51, 53]. When this is done early enough, the bone will reform with functional sutures, and the children may have normal neurocognitive development. Orbitofrontal advancement is usually required at a later stage. In severe cases, venous obstruction may lead to intracranial hypertension and hydrocephalus and hindbrain herniation [52, 53].
Children with complex multisutural craniofacial syndromes must be monitored for delayed intracranial hypertension, even if early decompressive surgery has been performed [54]. Raised ICP is considered in patients with bulging fontanelle, progressive frontal bone protrusion or turricephaly, headaches, irritability, and vomiting. Examination for papilledema has been considered the most reliable screening test, and it appears to be quite sensitive in children older than 8 years but relatively insensitive in younger children [49]. Patients with suspected intracranial hypertension should be evaluated with CT scan with bone windows or MRI scans of the head to look for hydrocephalus and shunted if appropriate. Patients with persistent headaches and normal-sized ventricles are candidates for cranial expansion if papilledema is present or scans reveal obliteration of basal cisterns. Patients without papilledema and in whom sutures are closed radiographically may be appropriate for invasive ICP monitoring with a fiber-optic device. The normal limit of resting ICP is poorly defined, but some authors have used 15 mmHg as a cutoff [55].
Children with severe hydrocephalus may acquire secondary craniosynostosis. With a functioning shunt, the head may have no stimulus for growth for several months until the brain expands to fill the calvarium, and the sutures may close because there is no driving force to keep them patent. These patients may show signs or symptoms of increased ICP with functioning shunts and small ventricles and tend to have frequent shunt malfunction. They may present with frequent headaches or with isolated papilledema and visual loss [56], underscoring the importance of routine ophthalmological care of these patients. The diagnosis is made by either skull films or 3-D CT scanning of the cranium to evaluate patency of the sutures and to look for the “copper-beaten” appearance of the skull. The surgical correction usually requires a major reconstruction of the cranial vault [57], including bifrontal expansion and orbital advancement or posterior vault distraction [58].
Patients with craniofacial syndromes may have accompanying brain malformations as well. It is important to identify the likelihood of developmental delay, so that the family may be counseled and reasonable choices can be presented regarding the appropriateness of cosmetic surgery. Patients with isolated sagittal, lambdoidal, and unilateral coronal synostosis are presumed to have normal developmental potential, and brain imaging is not required in most cases. Craniofacial syndromes may be divided into “nonsyndromic forms”, in which premature closure of a cranial suture is the sole manifestation of the condition, and “syndromic forms”, in which craniosynostosis is part of a more widespread complex, often with a defined inheritance pattern.
Nonsyndromic Synostoses
Approximately 85% of patients with craniosynostosis are nonsyndromic [59]. Premature closing of the sagittal suture (Fig. 40.12) is one of the most common forms of nonsyndromic synostosis. It is more common in male infants and is easily diagnosed by observing the classic scaphocephalic appearance of the head with frontal bossing. The orbits are not involved. There is no associated mental retardation, and raised intracranial pressure is infrequent (<25%), even in untreated cases. The diagnosis is established by clinical examination, and radiographic evaluation is not necessary in routine cases. A variety of surgical procedures have been described, all of which are successful in treating the deformity if carried out in the first 6 months of life [64]. The older child requires a total calvarial reconstruction, which is a formidable procedure [57].
Fig. 40.12
Sagittal craniosynostosis . (a, b) Premature closure of the sagittal suture disallows transverse growth and results in compensatory anterior–posterior growth leading to the typical scaphocephalic head shape. (c) A-P and lateral photograph of a child with established scaphocephaly
Lambdoid synostosis is quite rare and results in unilateral or bilateral flattening of the occiput accompanied by a palpable ridge over the lambdoid suture. A far more common cause of occipital flattening and cranial asymmetry is positional molding, or positional plagiocephaly . Infants are often encouraged to sleep on their backs, and if the child has a degree of torticollis, the infant will acquire a parallelogram configuration to the skull when viewed from above, with anterior displacement of the ear on the side of the flat occiput (Fig. 40.13). In severe cases, the frontal region will bulge on the opposite side. Increased intracranial pressure and developmental delay do not accompany either isolated lambdoid synostosis or positional molding, and treatment is directed at the deformity. In most cases, the condition spontaneously improves or responds to physical therapy for torticollis and positional devices that encourage the child to sleep on the opposite side. In more severe cases, a custom-fitted molding helmet may be utilized, but its utility is limited to the first 12 months of life. A CT scan with 3-D bone reconstructions may demonstrate cases of true lambdoid synostosis. Surgery is considered for children with marked deformity that has not improved sufficiently with conservative measures by 10 months to a year of age.
Fig. 40.13
Positional plagiocephaly . (a) Flattening of the right frontotemporal and left occipitoparietal region with compensatory expansion of the skull in the right occipital and left frontal position. (b) Superior view; from above; this does not represent a true craniosynostosis, but deformational change
Unilateral coronal synostosis (Fig. 40.14) is second only to sagittal synostosis as a form of single-suture closure. The appearance is characteristic (Fig. 40.15), with forehead flattening and supraorbital retrusion on the affected side. The orbit may also be elevated with a widened palpebral fissure while the ipsilateral cheek is flattened. The anterior–posterior (AP) skull radiograph or 3-D CT reconstruction will demonstrate the “harlequin” eye, corresponding to the clinically evident elevation of the superolateral orbital wall (Fig. 40.15c). Occasionally, it may be difficult to distinguish unilateral coronal synostosis from positional molding in early infancy. A period of observation may be helpful, since molding will often spontaneously improve, whereas true synostosis will not. Radiographic evaluation is helpful in doubtful cases. Raised intracranial pressure, hydrocephalus, and developmental delay are unusual in cases of unilateral coronal synostosis.
Fig. 40.14
Unicoronal synostosis . (a, b) The deformity of unicoronal synostosis resulting in ipsilateral frontotemporal orbital retrusion often associated with a compensatory transverse bulge on the ipsilateral side. (c) Note that, in early cases, symmetry of the malar region is frequently preserved as seen from above
Fig. 40.15
Unicoronal synostosis . (a, b) Left unicoronal synostosis seen in frontal projection and from above. Note the upward, outward slant, and widening of the palpebral fissures, deviation of the nasal root to the affected side, and absence of retrusion of the subjacent zygoma. (c) Three-dimensional image of a right unicoronal synostosis showing a fused coronal suture and the typical harlequin deformity to the orbit, which corresponds to those findings observed clinically
A procedure has been described that can be accomplished in early infancy in which the lateral orbital roof is greenstick fractured and the frontal bone is advanced [65]. At our institution, however, most patients undergo formal craniofacial reconstruction at 6–12 months of age when the orbit has sufficiently ossified to permit a rigid reconstruction. The procedure consists of bicoronal scalp incision and a unilateral frontal craniotomy on the affected side (Fig. 40.16a). In severe cases in which the opposite frontal area has severe compensatory bossing, a bilateral frontal craniotomy is preferred with or without bilateral osteotomy of the supraorbital bar [66]. Osteotomies of the orbital roof and frontozygomatic process are carried out, and the lateral orbital bar is advanced and rigidly secured with wire and microplates. The frontal bone is then also advanced and secured (Fig. 40.16b). The cosmetic result is usually satisfactory, with good to excellent results after 3 years expected in 89% of cases [66] (Fig. 40.17).
Fig. 40.16
Craniotomy and unilateral osteotomy . (a) Burr holes and lines of incision for craniotomy and unilateral osteotomy of the orbits. (b) Following ex vivo bending and manipulating, the osteotomized orbital segment is replaced in an anteriorly advanced position and fixated to stable basal bone. Replacement of the craniotomy following forceful bending completes the bony repair. In the infant, the small, bony gaps left posteriorly are filled with bone scraping harvested from the inner table of the frontal bone and will reossify
Fig. 40.17
Unicoronal synostosis , correction, and follow-up. (a) Preoperative frontal view showing patient with right unicoronal synostosis. Note the widened palpebral fissure with the superiorly and laterally displaced orbital roof and rim with temporal hollowing. The forehead on the affected side is flattened and blends into the orbital deformity. (b) Following unilateral fronto-orbital advancement and repositioning, the patient is seen 6 months postoperatively. Note improved symmetry in forehead, orbit, and palpebral fissure dimensions. (c) Same patient as shown in (a) and (b) seen 6 years postoperatively. In this case, normalization of the craniofacial skeleton in infancy has led to improved fronto-orbital growth on the affected side so that symmetry is maintained
Premature closure of the metopic suture (Fig. 40.18) results in keel-like narrowing of the frontal area (trigonocephaly), a pinched-in appearance of the lateral orbital and temporal regions, and often hypotelorism. Imaging studies will demonstrate the keel (Fig. 40.19) and aid in assessing the degree of true bony hypotelorism, which may be difficult to evaluate by simply observing the child, especially if there are accompanying epicanthal folds. Although increased intracranial pressure is uncommon, developmental delay may occur with trigonocephaly , due to coexisting midline brain anomalies, such as holoprosencephaly. In the absence of significant hypotelorism, surgery consists of bifrontal craniotomy , bilateral out-fracturing of the frontal bones leaving the midline bone affixed to the midline dura, and drilling of the midline keel of a bone [67]. The operation may be performed easily between 6 weeks and 6 months of age. When significant hypotelorism is noted or if there is significant retrusion of the lateral orbits, surgery is delayed until 6 months of age or older, so that midline osteotomies of the cranial base can be accomplished and the orbits can be moved laterally and anteriorly with interposition bone grafts to widen both the forehead and supraorbital bar [68, 69] (Fig. 40.20).
