chapter 16 AQ1 Craniosynostosis Jeffrey Weinzweig, MD / Stephen B. Baker, MD, DDS / Mitchel Seruya, MD AQ2 PATIENT EVALUATION AND SELECTION Surgical intervention is indicated in craniosynostosis Craniosynostosis is defi ned as the premature closure of both for the correction of calvarial contour deformities a cranial suture which causes abnormal calvarial growth. and the prevention of psychosocial dysfunction, intrac- Virchow’s law states that skull growth is arrested in the ranial hypertension, and/or mental retardation. Studies direction perpendicular to the fused suture and expanded have shown that the presence of intracranial hypertension at the sites of unaffected sutures, leading to characteris- is dependent on the number of affected sutures, ranging tic calvarial deformations. 1 This condition can be classi- from approximately 14% for single-suture synostosis to 2 – 3 fi ed into simple (single suture) versus complex (multiple approximately 47% in multisuture synostosis. Sutural sutures) and nonsyndromic versus syndromic subtypes release in simple craniosynostosis has been advised due to ( Tables 16-1 and 16-2 ). the concerns regarding increased intracranial pressure as Preoperative assessment for craniosynostosis includes a well as the mild but signifi cant developmental delay in the detailed medical history, physical examination, and radio- aging child. Patients with complex synostoses present with graphic imaging. Medical history should elicit skull irregu- increased severity of physical and neurological symptoms; larities, associated syndromes, family history of calvarial therefore, surgical intervention is even more imperative. deformities, and symptoms of intracranial hypertension (headache/vomiting, developmental changes, irritability, PATIENT PREPARATION and oculomotor paresis). Physical examination should Preoperative considerations include the optimal type and evaluate for characteristic calvarial shapes and asymme- timing of surgical correction for craniosynostosis. A broad tries, premature closure of the anterior fontanelle (normally range of surgical options exist in the armamentarium of open until 12–18 months of age), perisutural ridging, and contemporary craniofacial surgical reconstruction, all with signs of intracranial hypertension (papilledema, supraor- the primary objective of releasing the affected suture(s) bital retrusion, severe towering (turricephaly), and severe to permit normalization of skull growth in the setting frontal/occipital bossing). Head circumferences, cranial of accelerated cerebral growth. An open craniofacial indices, and anthropometric measurements should be approach remains the mainstay of therapy, relying on wide documented. scalp dissection, extensive calvarial osteotomies, and skull Radiological investigation may be necessary to corrobo- reconfi guration that is individually tailored to each cranial rate the diagnosis and/or rule out any associated intrac- vault deformity. 4 To address concerns regarding incision ranial abnormalities. Computed tomography remains the length, operative blood loss, and length of stay for open most sensitive barometer of bony fusion and may provide craniofacial procedures, minimally invasive techniques evidence for elevated intracranial pressure, as noted by ero- have been proposed. These techniques include endoscopic sion of the inner calvarial table (“copper-beaten” appear- sutural release, 5 spring-assisted cranioplasty, 6 and distrac- ance also referred to as “thumb printing”) (Figure 16-1 ). tion osteogenesis. 7 CT imaging and MRI are also helpful in evaluating the The optimal surgical age has been a source of contention, underlying brain for structural or functional abnormalities, given its differential effects on intraoperative hemodynam- including hydrocephalus, holoprosencephaly, cortical dys- ics, postoperative cranial growth, and subsequent mental plasias, and Chiari malformations. SSerletti_Ch16_galley.indderletti_Ch16_galley.indd 1 112/15/112/15/11 77:41:18:41:18 PPMM 2 • CHAPTER 16 development. While the literature is inconclusive regard- and suggests a role for the cranial base in metopic suture ing the appropriate timing for correction of craniosynosto- fusion. sis, the majority of craniofacial surgeons operate between Whereas a metopic notch describes the endocranial 3 and 12 months of age. Surgical age is also dependent on fi nding on axial CT images in patients with metopic synos- the type of surgical approach employed. Minimally inva- tosis, a corresponding three-dimensional groove is found sive techniques, which rely on dynamic cranial vault altera- on the endocranial surface of the actual skull that extends tion during rapid calvarial growth, are generally performed from the nasion to the anterior fontanelle in these patients. at an earlier age than open surgical correction. Weinzweig termed this clinical fi nding the metopic groove , Given the senior authors’ extensive experience with an anatomic abnormality that can reliably be found in open craniofacial reconstruction for craniosynostosis, sur- patients with metopic synostosis ( Figure 16-3 ). gical considerations, operative steps, and outcomes shall be In general, the goals of surgery are the normalization described for this type of surgical approach in the accom- of the forehead with reconstitution of a normal supraor- panying sections. In preparation for open craniosynostosis bital rim when necessary. Individuals presenting solely surgery, measures for ensuring adequate blood resuscita- with a prominent midline keel may be best served by sim- tion should be undertaken. These include obtaining a ple contouring of the frontal bone or by removal of the blood type and cross, autologous blood donation, and/or frontal bone fl ap followed by reconfi guration. Conversely, allogenic blood direct donation from a family member. patients with signifi cant trigonocephaly and hypotelorism Parents should be instructed that open craniosynostosis will require a fronto-orbital reconstruction, recontouring surgery is performed under general anesthesia. For most the frontal bone, and laterally expanding the orbits, often types of open craniosynostosis surgeries, patients are with cranial bone graft placed in the midline of the frontal placed in the supine position to facilitate calvarial expo- bandeau at the level of the nasion. sure. However, if the posterior vault is being addressed, as The essentials of fronto-orbital reconstruction involve in a lambdoidal synostosis or some sagittal synostoses, the a standard “stealth” (zig-zag) coronal incision, providing patient is ideally placed in the prone position. In the prone for adequate exposure of the fronto-orbital region while position, care must be taken to ensure adequate protection minimizing any postoperative scar. Perioperative antibiot- of the globes, facilitated by bilateral tarsorrhaphies and ics and steroids are given prior to the start of surgery. The periorbital cushioning. incision is infi ltrated with 0.5% lidocaine and 1:400,000 A plating system is used by most surgeons to main- parts epinephrine to minimize intraoperative bleeding. tain the proper position of the osteotomized bone seg- The frontal and temporal regions are dissected in the sub- ments after they have been placed in the desired position. galeal plane and care is taken to preserve the periosteum Historically, titanium was used but fell out of favor when on the surface of the bone, which helps minimize blood it was noted that the plates translocated with continued loss and may be used to stabilize osteotomized bony seg- calvarial growth. Resorbable plates eliminate the prob- ments. The dissection is taken down to the level of the lems associated with translocation. They maintain strength periorbital tissues, with caution taken to avoid any injury across the osteotomy long enough for the bone to heal but to the underlying globes. Following exposure of the frontal are resorbed by the body after several years. Most surgeons and orbital regions, the frontal bone is removed, providing today employ some type of resorbable fi xation for cranial access to the intracranial compartment. The supraorbital vault remodeling. rim is then removed in one piece to facilitate reconstruc- tion of the previously triangular-shaped supraorbital bar. TECHNIQUE Care is taken to remove suffi cient bone in the region of the sphenoid bone to allow for growth at the midface Metopic Synostosis (Trigonocephaly) and orbits. If the orbits require correction of hypotelor- ism, it will be necessary to displace the lateral walls of the Metopic synostosis is marked by a variable degree of phe- orbit as well as to split the midline and interpose a cal- notypic severity, ranging from mild ridging to the formation varial bone graft. Reconfi guration of the supraorbital bar of a triangular shaped head (trigonocephaly) or prominent often requires a midline osteotomy to facilitate a fl attened “keel” forehead with or without hypotelorism. Although forehead with additional partial-thickness bone cuts at the an endocranial ridge is not commonly seen in patients with lateral (pterional) angle to promote normalization of the metopic synostosis, an endocranial notch can be observed lateral supraorbital angle. The supraorbital reconfi gura- on axial CT images and is virtually diagnostic of prema- tion is maintained by the utilization of intervening bone ture suture fusion. Weinzweig termed this radiographic grafts as well as resorbable hardware. Following placement fi nding the metopic notch , a morphologic abnormality