Modifications in the surgical correction of trigonocephaly

The use of a single-piece bone flap for cranial reshaping in anterior craniosynostosis patients: clinical experience and a description of a novel technique

Background

Craniosynostosis is known as premature closure of one or more of the cranial sutures. Anterior craniosynostosis involves anterior plagiocephaly and trigonocephaly. One of the issues in anterior craniosynostosis skull reshaping is maintaining an aesthetically pleasing forehead curve. Therefore, in this article, we demonstrate our novel technique to use a single-piece bone flap for cranial reshaping of the anterior mold in patients diagnosed with anterior craniosynostosis. A retrospective record review of patients who underwent single piece bone flap cranial reshaping for correction of unicoronal synostosis (UCS) and metopic synostosis (MS) at an Academic Institute in Riyadh, Saudi Arabia, between 2018 and 2020, was conducted.

Results

Six non-syndromic consecutive patients were included. Three of the patients had MS. The mean age at surgery was 11.16 months (range, 6–19 months). The average OR time was 315 min (range, 263–368 min). The average intraoperative blood loss was 225 ml (range, 100–400 ml). All patients had achieved acceptable functional and aesthetic results.

Conclusion

Our novel technique is an innovative and efficient reconstructive technique to simultaneously address MS and UCS and minimize intraoperative bleeding and surgery time. However, more studies with more cases are required.

Part 1: Surgical Correction in 231 Trigonocephaly Patients - The Alder Hey Experience

ABSTRACT

Isolated metopic synostosis presents with a range of severity, from a palpable ridge as the sole presenting feature to a constellation of features resulting in trigonocephaly. At our unit, patients on the moderate to severe end of the phenotypic spectrum of trigonocephaly are offered fronto-orbital advancement and remodeling. The authors present our series of trigonocephaly patients who have undergone surgical correction. From January 2000 to January 2020, the authors operated on 231 patients with trigonocephaly. The average age at surgery was 18 months, with an average follow-up of 77.4 months. Seventy-nine percent of patients had no comorbidity. Ten percent of patients sustained a dural tear with no long-term consequences. The total early complication rate was 12.1%. The most common early complications were wound infection and wound dehiscence at 7.4% and 3.9% respectively. The total reoperation rate was 6.5%. The introduction of infection prevention and control measures over the 2 decades at our unit reduced the reoperation rate to 1.1%. The most common late complication was temporal recession in 20.8% of patients, none of whom required aesthetic correction. The recurrence rate of a metopic ridge was 2.3% with no patients requiring further surgery. None of our patients required calvarial remodeling for raised intracranial pressure after the primary fronto-orbital advancement and remodeling. There were no life-threatening complications or mortalities in our cohort. The authors present recommendations which include an infection control care bundle, cessation of surgical drains, and practice adjustments to reduce risks of infection and risk of requiring further calvarial remodelling for raised intracranial pressure.

A new approach of crenellated fronto-orbital advancement for the management of trigonocephaly: Technical note

Trigonocephaly is a craniosynostosis characterized by a premature fusion of the metopic suture associating a characteristic triangular head shape, with a frontal medial crest and hypotelorism. Various techniques have been described for its surgical treatment which is usually performed during the first year of life. However, there might be cases with a late referral, after the age of one year. One of the technical issues with a fronto-orbital advancement surgery in a child over one year of age is that there is a significant risk of persistent residual bone defects. This article describes a surgical technique of crenellated fronto-orbital advancement for correcting trigonocephaly in children over one year of age, allowing to reduce residual bone defects.

Anthropometric Outcomes following Fronto-Orbital Advancement for Metopic Synostosis

BACKGROUND

The authors' purpose is to present changes in anthropometric fronto-orbital dimensions after surgical correction of metopic synostosis.

METHODS

The authors retrospectively analyzed craniometric dimensions in older patients with metopic synostosis corrected by fronto-orbital advancement performed by the senior author (J.B.M.). Preoperative and postoperative linear measures (frontal breadth, cranial width, and intercanthal distance) were taken by direct anthropometry. Interdacryon distance and width of the bandeau were also recorded intraoperatively, before and after widening. Follow-up anthropometric values were compared to age- and sex-matched normative data and standard (z) scores were calculated.

RESULTS

Sixteen patients met the inclusion criteria. Syndromic diagnosis was documented in five of 16 patients. Average age at the last postoperative evaluation was 8.9 ± 3.8 years (range, 4 to 16 years). Mean frontal width z-scores decreased postoperatively from 0.82 to -0.32 (p = 0.007), indicating diminished growth in this dimension. The last measured frontal width strongly correlated with the breadth of the bandeau after surgical correction but not with preoperative values. Postoperative mean cranial width diminished significantly to a more normal value. Mean intercanthal distance was normal preoperatively and remained so but was significantly greater in syndromic than in nonsyndromic cases.

CONCLUSIONS

Frontal growth rate is diminished in the coronal plane after fronto-orbital advancement. The authors recommend primary techniques to overcorrect the width of the bandeau and frontal region, including zygomaticosphenoid osteotomies and interpositional cranial bone grafts to advance/widen the lateral orbital rim. Continued evaluation is required to assess whether overcorrection results in normal frontotemporal shape and breadth at skeletal maturity.

Does the Use of Particulate Bone Graft Increase the Incidence of Postoperative Infection in Surgery for Craniosynostosis?

Objective

The use of particulate bone graft (PBG) has become an accepted technique for filling cranial defects created during cranial vault expansion for craniosynostosis. However, the use of PBG may be a risk factor for postoperative infection. The aim of this study was to compare the rate of postoperative infection in patients who received particulate bone graft (PBG+) with that in patients who did not (PBG–).

Design

An Institutional Review Board–approved, retrospective, cohort study of consecutive patients was performed. Twenty-seven consecutive patients in the PBG– group were compared with 21 consecutive patients in the PBG+ group. The two cohorts were assessed for incidence of surgical-site infection.

Results

Statistical analysis was performed using the Fisher exact probability test. Surgical site infection occurred in none of the PBG– patients (0%) versus one of the PBG+ patients (4.76%). This difference in infection rates between the two cohorts was not statistically significant ( P = .4375).

Conclusions

Although there may be concern that PBG could serve as a facilitative medium for bacterial growth, this study demonstrates no statistically significant increase in infection rates with its use. Particulate bone grafting of cranial defects resulting from cranial vault expansion in craniosynostosis remains a useful and valuable technique.

Trigonocephaly: A simple modified technique

Trigonocephaly is the premature fusion of the metopic suture leading to deformation of anterior calvarium causing keel shaped deformity of forehead. In most cases, surgical correction is for aesthetic and psychosocial reasons. Various techniques have been described. Here we describe a technique, which is simple to perform with good postoperative results. Metopic suture is excised, one side is reconstructed in finger clasping manner to fit in an expanded area, and the other side is transected and simply molded, and all these fixed with nonabsorbable suture. Supraorbital horizontal bar is mobilized on either side anteriorly and fixed with titanium plate and screws.

The shell technique: bilateral fronto-orbital reshaping in trigonocephaly

The shell technique, used in the Pediatric Neurosurgical Department at the Catholic University, Rome, since the 1990s for the correction of trigonocephaly, is associated to a significant reduction in surgical time and intraoperative blood loss as compared to other procedures, while allowing an adequate remodelling of the bifrontal bone by means of multiple radial osteotomies. The technique does not necessitate the creation of a supraorbital bar, as the supraorbital ridges are modified in situ, further reducing the operative blood loss. In spite of reduced surgical time and manipulation, this procedure ensures aesthetic and functional results comparable to more extensive and complex cranial vault reshaping procedures. The main limitation of this technique is related to the surgical timing, as better results are obtained between 3 and 9 months of age, when the skull bone is still ductile to work with, thus allowing it to be remodelled by greenstick fractures. Moreover, in this age group, the cranial defects that result from the enlargement of the frontal bone flap by means of radial cuts and from the anterior displacement of its lateral portions may benefit from the more effective bone regeneration which characterizes younger children as compared to their older counterparts. A small number of cases showing either persistent hypotelorism or temporal depression have been observed in the post-operative period, although these residual deformities probably depend on a more extensive involvement of the cranial base in the synostotic process in these patients than on the procedure itself.

Value of preoperative imaging in the diagnostics of isolated metopic suture synostosis: a risk-benefit analysis

Radiographic evaluation including plain radiographies and computed tomographic (CT) scans are considered as a necessary tool for diagnosis of craniosynostosis. As recently concerns about harmful effects of ionising radiation in children have been raised, some authors have suggested the use of magnetic resonance imaging (MRI) as a helpful alternative in preoperative imaging of patients with isolated metopic synostosis. Besides confirming the diagnosis of trigonocephaly, MRI is the superior technique for the evaluation of underlying brain anomalies. However, if the benefit of preoperative imaging justifies possible side effects is still discussed controversially. Hence, this study investigated the value of preoperative imaging for the diagnosis of isolated synostosis of the metopic suture compared to a sole clinical examination. In a series of 63 cases with isolated metopic craniosynostosis operated at the Department of Oral and Maxillofacial Surgery, 48 (76.2%) patients received additional radiography or MRI investigation, while in 15 (23.8%) patients the diagnosis was based on clinical examinations only. In all patients, diagnosis was confirmed intra-operatively by a fused metopic suture. CT scans with three-dimensional reconstruction (12.5%) or plain radiographs (39.6%) did not provide any additional benefit for the diagnosis or the surgical treatment. In 23 patients (47.9%), MRI showed the typical soft-tissue alterations like triangular brain deformation in the frontal area. Besides these findings, no brain or other underlying anomalies were diagnosed which had required any additional treatment. The incidence of underlying brain abnormalities in isolated metopic synostosis seemed not to be different from that of the general population. As the characteristic clinical manifestations were sufficient for an accurate diagnosis of isolated metopic synostosis, and with respect to the biological effects of ionising radiation and risks of sedation especially in infants, preoperative imaging should be reduced to a minimum.

Metopic synostosis

Premature closure of the metopic suture results in a growth restriction of the frontal bones, which leads to a skull malformation known as trigonocephaly. Over the course of recent decades, its incidence has been rising, currently making it the second most common type of craniosynostosis. Treatment consists of a cranioplasty, usually preformed before the age of 1 year. Metopic synostosis is linked with an increased level of neurodevelopmental delays. Theories on the etiology of these delays range from a reduced volume of the anterior cranial fossa to intrinsic malformations of the brain. This paper aims to provide an overview of this entity by giving an update on the epidemiology, etiology, evolution of treatment, follow-up, and neurodevelopment of metopic synostosis.

Surgical treatment of trigonocephaly: technique and long-term results in 48 cases

OBJECT

The authors present their experience in the surgical treatment of metopic synostosis by orbital bandeau remodeling and frontal bone rotation. The pitfalls and advantages of the surgical technique are discussed, along with the long-term clinical results in 48 consecutive cases.

METHODS

Forty-eight consecutive patients in whom trigonocephaly was diagnosed between 1990 and 2009 were treated with frontal bone rotation and frontoorbital bandeau remodeling. Of these patients, 38 (79%) were boys and 10 (21%) were girls. The age at the time of surgical treatment ranged between 4 and 42 months (mean ± SD 11.4 ± 8.7 months). The average follow-up period was 5.5 ± 4.2 years (range 5 months-19 years). The preoperative and latest postoperative photographs of the patients were evaluated for the following features: 1) shape of the forehead; 2) hypotelorism; and 3) temporal depression. Scores of 0, 1, or 2 were assigned for each item: 0 was normal, 1 meant moderate deformity, and 2 denoted severe deformity.

RESULTS

In the early postoperative period, no complications were documented. The average hospitalization period was 4 days. Follow-up radiographs or 3D CT scans were obtained at regular intervals. The mean preoperative scores for the evaluated items were 1.38 ± 0.49 for the shape of the forehead, 1.33 ± 0.48 for hypotelorism, and 1.7 ± 0.46 for the temporal depression. The mean postoperative scores were 0.06 ± 0.24 for the shape of the forehead, 0.21 ± 0.4 for hypotelorism, and 0.67 ± 0.48 for the temporal depression. Overall, the total preoperative score dropped from 4.4 to 0.93 postoperatively (p < 0.05). All the patients were contented with the cosmetic results.

CONCLUSIONS

Early detection and treatment of metopic suture synostosis has a significant, favorable influence on the outcomes. Good understanding of the structural abnormality and the pathophysiological mechanisms of the possible complications is very important for performing proper surgical reconstruction.

Fronto-orbital advancement using an en bloc frontal bone craniectomy

BACKGROUND

Fronto-orbital advancement is a procedure commonly performed in craniofacial centers for coronal and metopic suture synostosis. Several variations of the technique have been reported.

OBJECTIVE

To describe our modifications to the anterior cranioplasty procedure and the results of our surgical series.

METHODS

Using our craniofacial database, we retrospectively analyzed the records of all patients undergoing fronto-orbital advancement for craniosynostosis. The same team of neurosurgeons and plastic surgeons performed all procedures. Demographic data, operative time, blood loss, length of stay, and clinical outcome were analyzed.

RESULTS

Of 248 patients treated for craniosynostosis, a total of 70 patients underwent fronto-orbital advancement. Nineteen presented with metopic, 26 with unilateral coronal, 17 with bilateral coronal, and 8 with multiple synostosis. Median age at surgery was 6.5 months. Mean operative time was 210 minutes; mean blood loss was 167 mL; and length of stay was 4.5 days. A positive correlation was found between operative time and blood loss (r = 0.1, P < .01) and age at surgery and blood loss (r = 0.3, P < .0001). There was a minor morbidity rate of 2.9%. A good reconstruction was obtained in all patients using our en bloc fronto-orbital advancement without any midline osteotomies at a mean follow-up of 15 months.

CONCLUSION

A team approach and the application of a standardized surgical technique should make it safer to operate in young children, shorten the surgical time, and lead to a reduction in blood loss. Reconstructing the frontal bone as an entire unit yielded excellent correction for coronal and metopic synostosis.

Spring-Assisted Correction of Hypotelorism in Metopic Synostosis

BACKGROUND

Metopic synostosis, apart from the pointed forehead, typically is characterized by hypotelorism with egg-shaped orbits on cephalography and the frontoorbital axis parallel or even converging superiorly. The frontoorbital axis angle is a novel parameter for analyzing and describing the orientation of the orbits. Current methods of surgery often result in undercorrection of the almost ever-present hypotelorism. The present study was performed to analyze a new technique, capable in this respect, using steel wire springs in conjunction with a cranioplasty.

METHODS

A retrospective study of 23 metopic synostosis patients operated on between 1999 and 2004 was conducted. A strip midline craniectomy and frontal reshaping were combined with the insertion of a steel wire spring across the midline craniectomy, forcing lateral displacement of the orbits. Preoperative and postoperative follow-up cephalograms were obtained, and the bony medial interorbital distance was measured and compared with the bony medial interorbital distance of a control group. Perioperative data and complications were noted.

RESULTS

Preoperative mean bony interorbital distance was 10.6 mm (range, 7.7 to 13.2 mm). It increased to 15.7 mm (range, 10.4 to 22 mm) at 1.5 months postoperatively and to 16.2 mm (range, 10.9 to 24.5 mm) 5 months postoperatively. Results as judged clinically ranged from little effect to a definitive overcorrection. The frontoorbital axis was improved in every case. Average frontoorbital axis was -4 degrees (range, -33 to 23 degrees) preoperatively and 28 degrees (range, 11 to 46 degrees) postoperatively.

CONCLUSION

It was concluded that a spring used together with a cranioplasty is a powerful tool for the correction of both hypotelorism and orbital shape in trigonocephaly.

Dynamic Spring Mediated Cranioplasty in an Experimental Model With Resorbable Foot Plates

Craniofacial surgery continues to be progressive in its approach to maximize function and aesthetic appearance while minimizing risks and complications. Dynamic springs are one way to minimize invasiveness while achieving favorable results. The purpose of this study was to show the safety and efficacy of dynamic springs with resorbable foot plates for treatment of metopic suture abnormalities in a swine model. The study population consisted of twelve 20 kg Chester swine. The swine were divided into two treatment groups: four in the sham surgery group and eight in the stainless steel spring group. Postoperative analysis consisted of evaluation of the skull growth over time and integrity of the foot plates and underlying dura. The swine, killed at 8 weeks, were examined for spring location in the foot plates, ease of removal of the spring, and postmortem histologic analysis of the bone growth. No morbidity or mortality occurred in the immediate perioperative period secondary to the surgery. Postmortem histologic analysis revealed no infections or complications related to the surgery. Statistical analysis using a mixed linear model with an unstructured variance-covariance matrix was fit. In conclusion, this study confirms the efficacy and safety of the spring-mediated cranioplasty at the metopic suture with use of resorbable foot plates in a swine model.

Trigonocephaly: surgical considerations and long term evaluation

Trigonocephaly accounts for approximately 10% of all craniosynostosis. Severe trigonocephaly results in a triangular-shaped forehead, superior-lateral orbital depression, hypotelorism, and compensatory occipital-parietal calvarial changes. Radiographic findings include ovoid orbits with parallel medial borders, thickened keel-shaped frontal bone, small ethmoid sinuses, and a short anterior cranial fossa with pitched sphenoid wings. Our experience with 50 infantile cases of severe nonsyndromic trigonocephaly patients treated from 1987 to 2005 is clinically reviewed to assess long-term growth based on a standardized operative technique. The average age of the patients at surgery was 6 months and the mean follow-up was 12 years. Our complication rate was 2%; the reoperative rate was 12%. The use of resorbable rigid plate fixation combined with alloplastic augmentation has improved the cosmetic outcome in patients treated since 1996 and reduced the reoperative rate.

Pitfalls for the pediatrician: positional molding or craniosynostosis?

Abnormal head morphology is common among infants and often leads parents to ask their pediatricians for guidance. While the vast majority of such children development and prevent adverse neurobehavioral sequelae secondary to increased intracranial pressure or impaired cerebral growth. The coordination of a multidisciplinary team in the setting of a center experienced in the management of craniosynostosis will assure the best possible results for each patient.

Surgical correction of metopic synostosis

BACKGROUND

Premature closure of the metopic suture results in deformation of the anterior portion of the calvarium, which can vary from mild to severe. In mild forms, there is only prominent ridging of the metopic suture; more severe forms result in a marked narrowing of the frontal and temporal regions that in turn affects the supraorbital rims and produces hypotelorism.

METHODS

The authors retrospectively reviewed 39 consecutive cases of metopic synostosis treated over a 12-year period.

RESULTS

The average age at referral was 5 months, with surgery performed at an average age of 7.5 months. Fifteen infants had other congenital anomalies, with eight having synostosis of other sutures. Follow-up ranged from 7 months to 6 years, with an average of 29 months. In three mild cases, burring of the metopic ridge was performed with excellent aesthetic results in all cases. The other 36 patients had significant deformity of the supraorbital ridges and temporal regions, with obvious hypotelorism for over 50% of the time. In these cases, the patients underwent craniofacial reconstruction to normalize their appearance. In addition, the lateral aspect of the sphenoid ridges, including the orbital roof and lateral orbital wall to the infraorbital fissure, was removed to free the cranial base. The average blood loss was under 400 ml and the average hospital stay was 3.6 days. Results were considered good to excellent in all except three cases, which had recurrence of a prominent metopic ridge; two required a second operation after 6 months for burring of this ridge, whereas the third was treated conservatively with an orthotic headband.

CONCLUSION

Mild forms of metopic synostosis can be successfully treated with burring of the metopic ridge alone. Severe forms require craniofacial reconstruction and may be associated with other congenital abnormalities, additional synostosis, and developmental delay. In all cases, the operative procedure must be tailored to the nature and severity of the deformity.

Surgical treatment of trigonocephalies and associated hypoteleorbitism

Premature closure of metopic suture is a relatively uncommon form of craniosyostosis with an estimated incidence of 0,3 per 1000 live births, comprising about 7% of surgical craniosynostosis referred to craniofacial centers. A broad phenotypical spectrum spreads from minor metopic ridges to severe trigonocephaly with pterional indentation supraorbital bar retrusion, temporal and parietal compensating bossings and hypotelorism. Most of the cases arise spontaneously although autosomal dominant inheritance has been described and association with cromosomal abnormalities and different syndromes has been widely reported. Surgical correction has been attempted with good cosmetic results using several variations of the standard frontoorbitary advance. However there is still a number of questions to be solved in relation to this entity, mainly on its pathogenesis, but also on its development, natural history and treatment. Direct surgical approach to associated hypotelorism is a matter of argument when considering the reestablishment of normal interorbitary distances. We have conducted a retrospective analysis of our serie consisting of twenty-eight cases of trigonocephalies. Surgical correction of hypotelorism was attempted in eleven cases while the resting seven children remained "not treated". The objective was to review the functional outcome and cosmetic results comparing the different techniques applied to the frontal bone and to observe evolution of the hypoteleorbitism after the treatment with or without osteotomies and grafting of the nasoethmoidal area.

Trigonocephaly in rabbits with familial interfrontal suture synostosis: the multiple effects of premature single-suture fusion

Previous studies from our laboratory have characterized the craniofacial morphology and growth patterns of an inbred strain of rabbits with autosomal dominant coronal suture synostosis. A number of rabbit perinates from this colony have been collected sporadically over a 5-year period with premature interfrontal suture synostosis. The present study describes the very early onset of craniofacial dysmorphology of these rabbits and compares them to similar-aged normal control rabbits. A total of 40 perinatal New Zealand White rabbits were used in the present study. Twenty-one comprised the sample with interfrontal suture synostosis and ranged in age from 27 to 38 days postconception (term = 31 days) with a mean age of 33.53 days (+/-2.84 days). Nineteen rabbits served as age-matched, normal controls (mean age = 33.05 days +/-2.79 days). Lateral and dorsoventral radiographs were collected from each rabbit. The radiographs were traced, computer digitized, and 12 craniofacial measurements, angles, and indices were obtained. Mean measures were compared using an unpaired Student's t-test. All synostosed rabbits were stillborn or died shortly after birth. Grossly, these rabbits exhibited extreme frontal bossing, trigonocephaly with sagittal keeling, and midfacial shortening. No somatic anomalies were noted. Radiographically, rabbits with interfrontal suture synostosis had significantly (P < 0.05) narrower bifrontal widths, shorter cranial vault lengths, kyphotic cranial base angles, and different cranial vault indices (shapes) compared to controls. Results reveal severe and early pathological and compensatory cranial vault changes associated with premature interfrontal suture synostosis in this rabbit model. The 100% mortality rate noted in this condition may be related to the inheritance of a lethal genetic mutation or to neural compression from reduced intracranial volume. Results are discussed in light of current pathogenic hypotheses for human infants with premature metopic suture synostosis.

Evaluation of a surgical technique for trigonocephaly

Clinically diagnosed trigonocephaly have been treated by a standard surgical technique developed at Göteborg University Craniofacial Unit. To evaluate the technique we designed a study to include both subjective and objective assessments. Of 30 patients operated on between 1988-1997, 15 patients with at least three years postoperative follow-up have been included. An evaluation of the surgical outcome of the bitemporal width, the forehead contour, and the intercanthal distance was made both subjectively using a visual analogue scale (VAS) and objectively with analyses of cephalograms taken preoperatively and postoperatively at 3 and 5 years of age. For the subjective evaluation a control group of 10 randomly selected children from a Child Welfare Centre were selected. For the objective evaluation the control group consisted of cephalograms from children born with cleft lip and palate who were matched regarding sex and age. Both cephalometric analysis and subjective studies of the outcome indicated improvement. When the forehead contour was investigated the number of patients who had been improved or corrected completely was higher when evaluated subjectively. When interorbital distance on cephalograms and intercanthal distance scores on VAS were evaluated, again the subjective study indicated improvement in more subjects.

Three-dimensional morphological analysis of isolated metopic synostosis

Morphological differences were quantified in three-dimensions among individuals with untreated isolated metopic synostosis and between those individuals and similar aged-matched normal dry skulls to test two hypotheses: first, that the dysmorphology is a self-correcting condition; and second, that a lack of vertical growth of the skull produces this dysmorphology. Three-dimensional (3D) coordinates were recorded for 22 craniofacial landmarks from CT scans of 15 metopic patients, ranging from 5- to 32-months-old, and of four normal dry skulls, ranging in age from 6- to 36-months-old. The patient population was diagnosed with isolated metopic synostosis at The Johns Hopkins Medical Institutions in Baltimore, Maryland or Children's Hospital in St. Louis, Missouri. Comparisons between the metopic age groups indicate that the trigonocephalic phenotype worsens through time. Between 5 and 14 months, the neurocranium displays an increase in vertical growth. This was followed by a lack of vertical growth between 14 and 32 months. The face displays a lack of vertical growth from 5 to 14 months and an increase in vertical growth after 14 months. Comparisons between the metopic age groups and the normal skulls indicate that the trigonocephalic head is taller superoinferiorly and longer anteroposteriorly. Relative to the normal phenotype, the inferior temporal region in the metopic phenotype is narrow. These findings enabled the rejection of both hypotheses and localized form differences between normal and metopic phenotypes. Based on these results, we suggest that the trigonocephalic phenotype worsens with age and the amount of vertical growth that produces the trigonocephalic phenotype varies throughout growth with respect to location within the skull and age.

Analysis and treatment of severe trigonocephaly

A retrospective analysis of seven patients with clinically severe trigonocephaly was performed, including a review of preoperative and postoperative computed tomography scans. A method of analyzing the trigonocephalic deformity was developed. This is based on determination of the angular severity of the forehead (110 +/- 4 degrees) and the length of half of the supraorbital bar (40 +/- 3 mm). This central angle was found to be relatively constant in this population. Using simple trigonometric relationships, a rationale for the alternative method of reconstruction used in these patients is presented. This technique is based on transverse expansion of the supraorbital bar, transposition of the lateral orbital rim, expansion of the temporal fossa, and recontouring the orbital aperture. As a separate consideration and step, the bony interorbital distance is widened.

Metopic synostosis: in favour of a "simplified" surgical treatment

Metopic synostosis is a relatively simple form of craniosynostosis, resulting from premature fusion of the metopic suture. In this pathology different degrees of dysmorphia of the anterior cranial fossa and the presence of associated anomalies of the skull might enable specific subgroups to be identified. Since most functional and cosmetic anomalies benefit from early surgical treatment, over the last few years neurosurgeons have been forced to elaborate less drastic, but nonetheless effective, surgical techniques. In the present report we analyze the surgical results obtained in a series of 62 infants with trigonocephaly operated on within their 1st year of life. Patients were subdivided into two groups (group I: 8 patients; group II: 54 patients) according to the specific dysmorphic characteristics of the frontal bone and anterior cranial fossa, and the presence of compensatory deformities affecting the anterior cranial base and temporo-parietal region. All the patients were treated using one of two relatively simple surgical techniques (procedure A: inversion of two hemifrontal bone flaps--48 cases; procedure B: the "shell" operation--14 cases). Both surgical procedures appeared to be effective, allowing adequate functional and cosmetic correction of the cranial deformity. In patients operated on following procedure B surgical time and blood loss were dramatically reduced. Long-term outcomes were satisfactory in all cases, irrespective of the surgical technique used. In the group II patients, however, progressive normalization of the interorbital distance was constantly observed, suggesting a different degree of stenotic involvement at the level of the anterior cranial base in these patients.

Trigonocephaly-associated hypotelorism: is treatment necessary?

This study was designed to examine whether hypotelorism associated with trigonocephaly might be self-correcting. Only patients who required surgical treatment and had undergone preoperative and postoperative anthropometric measurements were included. In no case was any attempt made to correct the hypotelorism surgically. The study sample consisted of 16 patients, of whom 10 underwent preoperative and postoperative computed tomography in addition to anthropometric examinations. The results were compared with sex- and age-matched pooled normal standards, converted to standard Z scores, and analyzed by means of Student's t tests. Both intercanthal and interorbital widths increased significantly postoperatively, with improvements in delta Z scores of 0.445 (p < or = 0.01) and 0.638 (p < or = 0.05). These increases exceeded average growth increments by 1.6 mm for intercanthal width and 1.3 mm for interorbital width. Improvement in the intercanthal widths was significantly greater in the more severely affected children than in those whose conditions were less severe. A greater improvement in interorbital width also was noted in children treated at less than 6 months of age compared with those treated later. The younger the patient at surgery, the greater was the improvement, suggesting that early surgery may somehow release a constraint on interorbital growth.

Long-term studies of metopic synostosis: frequency of cognitive impairment and behavioral disturbances

Although the occurrence of cognitive impairment and behavioral disturbances in patients with metopic synostosis has been described, the incidence of this dysfunction has not been established. The records of 36 consecutive children with metopic synostosis followed at one craniofacial center from 1978 to 1993 were reviewed and parental questionnaires were completed to establish the frequency of mental retardation, learning disabilities, and behavioral problems associated with this synostosis. Documentation of syndromes, abnormal karyotype, and central nervous system anomalies also was done. The study group consisted of 27 males and 9 females. The average age at most recent follow-up was 7 years and 1 month (range 6 months to 22 years). Two patients had chromosomal abnormalities (9p syndrome and trisomy 21). On the basis of CT and MRI scans, intracranial anomalies were identified for only one patient having an absent corpus callosum. Thirty-two of the study patients had adequate information for longitudinal assessment. Twenty patients have normal development without apparent disability. Of these, those of school age are at appropriate grade level. Eight patients have mild to moderate learning disabilities or behavioral problems, including attention deficit/hyperactivity disorder and impaired language development. Four patients have significant mental impairment. Impaired cognitive development was not limited to children with abnormal karyotype or central nervous system anomaly. Cognitive and behavioral abnormalities occur in at least a third of patients with metopic synostosis. The, at times, subtle nature of these abnormalities mandates longitudinal developmental and neurologic evaluation for infants with metopic synostosis.