Unicoronal Synostosis Research Articles

Late Results After Unicoronal Craniosynostosis Correction

The authors report nine patients with unicoronal synostosis who were treated with the same surgical protocol and who now have reached skeletal maturity. These patients all underwent surgery at the Australian Craniofacial Unit during a 2-year period by one of two craniofacial surgeons and one of two neurosurgeons. The operative procedure in all of these cases was the same technique, in which there was unilateral advancement of the affected side. No cases required reoperation; however, one case subsequently required revision of the coronal scar, and two cases required strabismus correction. All cases were reviewed to evaluate patient results by the clinical staff; recent photographs at skeletal maturity also were reviewed. Two patients had adult computed tomography scans available for skeletal assessment, and one additional patient had undergone serial computed tomography scans during childhood. The patients also completed an anonymous questionnaire to ascertain their assessment of their appearance. The results of the clinical and radiologic assessments and questionnaire suggest that the operative procedure undertaken in these cases has produced satisfactory results in the long term, with few individuals requiring (or even considering) additional surgery, despite some persistent asymmetry.

820 Endoscope-assisted Fronto-orbital and Cranial Osteotomies

INTRODUCTION: An operative approach has been developed that incorporates fronto-orbital and cranial osteotomies to achieve immediate correction using specially designed bioresorbable plates and screws. Postoperative helmet/band therapy may be eliminated or its duration shortened using these techniques. METHODS: Forty-two patients (age, 2 to 8 mo) with sagittal (n = 25), metopic (n = 11), unicoronal (n = 5), or lambdoidal synostosis (n = 1) underwent endoscopic craniosynostosis repair with complex osteotomies performed through two or three small incisions in the scalp and/or upper eyelids. Suturectomy was performed in concert with wedge osteotomies, outfracture of parietal plates, reduction of cranial length, and stabilization with resorbable plates and screws for patients with sagittal synostosis, whereas unilateral or bilateral fronto-orbital advancement was performed for children with unilateral coronal (UCS) and metopic synostosis, respectively. Specially designed bioresorbable plates were used for fixation when appropriate. RESULTS: Follow-up has ranged from 1 month to 2 years. One patient developed bleeding in the recovery room that required transfusion. One patient with UCS required conversion to the open procedure. One patient with UCS will require reoperation. All patients were discharged by hospital Day 3. Two patients with sagittal synostosis had a small protrusion on the vertex of the cranium despite postoperative helmet therapy. Satisfactory to excellent aesthetic results were obtained in the remaining cases. In five of the children, helmets were not used. The others were placed in postoperative helmets for 6 to 12 weeks. CONCLUSION: Preliminary results are encouraging. More follow-up is necessary to determine selection criteria and critically evaluate outcomes. With more experience and refinement of instrumentation, minimally invasive repair will become an important tool in surgical management of craniosynostosis.

Plagiocephaly: morphometry of skull base asymmetry.

The aim of this study was to perform a morphometric analysis of the skull base to understand the mechanism of asymmetry between malformational and deformational plagiocephaly. Since 1988, we have carried out 102 CT scans with three-dimensional reconstruction of the endocranial side of the skull base. There were 20 cases of malformational plagiocephaly, consisting of 18 unicoronal synostoses (UCS) and two unilambdoid synostoses (ULS), and 82 cases of plagiocephaly without synostosis, made up of 60 cases of frontal plagiocephaly (FP) and 22 of occipital plagiocephaly (OP). The skull base asymmetry was analyzed in three ways: (1) the hemibases and the cranial fossa angles were compared with each other; (2) the structural asymmetry of the chondrocranium was calculated; and (3) the architectural asymmetry was measured in relation to the medio-labyrinthine plane. The skull base asymmetry of malformational plagiocephaly was located in the anterior and middle cranial fossae for UCS and in the posterior and middle cranial fossae for ULS. The asymmetry was the result of a localized structural anomaly of the chondrocranium. The asymmetry of deformational plagiocephaly corresponded to a distortion in relation to the medio-labyrinthine plane while the chondrocranium remained symmetric. The skull base asymmetry of malformational plagiocephaly is secondary to a localized malformation of the chondrocranium, and that of the deformational plagiocephaly is secondary to an architectural deformation.

Neurocranial suture autotransplantation and periosteal dura stripping to provide a passive growth site in craniosynostosis – a case report

Aim: The behaviour of a neurocranial suture autograft in a plagiocephalic infant is described. Patient and methods: In a 7-month-old girl, born with right-sided unicoronal synostosis, part of the left-sided unicoronal suture was transplanted to the right-sided synostosectomy site. Also, in the pathological area, the periosteal ‘layer’ of the dura was surgically removed. The suture autotransplantation was integrated into the classical concept of radical remodelling, planned in a computer design environment. Growth of the suture was monitored by CT. Results: Suture patency and osseous growth within the autograft could be demonstrated over a 1-year period. Conclusion: Neurocranial suture autotransplantation together with the prohibition of fusion-inducing dural signals seems to be a promising technique in the treatment of certain premature synostoses. This warrants a prospective clinical trial.

Changes in orbital volume during childhood in cases of craniosynostosis.

Controversy remains concerning the timing of frontoorbital advancement (FOA) surgery performed for craniosynostosis. Reduced orbital volume and degree of exorbitism are often cited as reasons for early surgical intervention. To date, however, little attention has been given to orbital volume and its changes during the first few years of life as an indicator of orbital growth in children with craniosynostosis. Knowledge of orbital volume and growth patterns in individuals with craniosynostosis and those with normal cranial structures will enable surgeons to refine both the type and timing of surgical intervention required, thus obtaining the optimum outcome for their patients. Using the procedure of segmentation, orbital volumes in 50 children with various forms of craniosynostosis were measured on preoperative computerized tomography scans. Changes in average volume that occur with increasing age were calculated and compared with a model of normal orbital volume growth. At presentation the children with craniosynostosis ranged in age from 1 to 29 months, with 82% of them within the 1st year of life. Several interesting observations emerged from this study. Excluding patients with unilateral coronal synostosis, there was no difference between orbital volumes measured on the right and left sides, allowing mean orbital volume measurements to be used for comparative purposes. Although children with craniosynostosis begin life with significantly smaller orbital volumes, overall normal mean volumes for both sexes are attained by 13 months of age, with volumes approaching normal by 6 months of age in male infants and by 8 months of age in female infants. Changes in orbital volume associated with age generally appear to be similar in most forms of craniosynostosis. There appears to be no significant difference in changes in orbital volume between children with syndromic or nonsyndromic forms of bicoronal synostosis. Orbital volume is significantly reduced on the ipsilateral affected side in cases of unicoronal synostosis in comparison with the contalateral side, but it is not significantly lower than that of normal. Finally, FOA surgery appears to restore normal growth of orbital volume. The results of this study indicate that the underlying mechanism leading to craniosynostosis and restriction of orbital volume "burns out" and begins to lose its major effects within the first few months of life. It would appear that FOA surgery should be delayed until the end of the second half of the 1st year of life, thus maximizing the effects of accelerated normal orbital growth and reducing the risks of relapse.

Clinical characteristics of patients with unicoronal synostosis and mutations of fibroblast growth factor receptor 3: a preliminary report.

Clinical teaching dictates that isolated unicoronal synostosis is sporadic in occurrence and is possibly related to intrauterine constraint. Despite this, isolated reports document a familial occurrence. It has previously been recognized that there may be a familial pattern of inheritance. Recently, mutations in fibroblast growth factor receptors (FGFRs) have been implicated in several syndromic craniosynostoses. At the authors' institution, mutations in FGFR3, located at chromosome 4p16, have been found to cause coronal synostosis. Two cases of unicoronal synostosis were found to have the same Pro250Arg missense mutation in FGFR3. This finding suggested that all patients with a diagnosis of unicoronal synostosis be screened for the FGFR3 mutation. Between January and December of 1996, patients with a diagnosis of plagiocephaly at the Children's Hospital of Philadelphia were evaluated for the FGFR3 mutation. Thirty-seven patients with unicoronal synostosis had mutational studies. Two additional patients were known to have the FGFR3 mutation at the onset of the study. Of the 37 patients screened, four were found to have the FGFR3 mutation, for a total of six patients with both unicoronal synostosis and the FGFR3 mutation. All patients with unicoronal synostosis were evaluated for facial dysmorphology and operative outcome. The six patients with the FGFR3 mutation had more severe cranial dysmorphology and were more likely to need surgical revision than those without the FGFR3 mutation. The occurrence of the FGFR3 mutation among patients with unicoronal synostosis provides evidence for a genetic basis of certain forms of plagiocephaly. The clinical, radiologic, and molecular findings will be an important addition to the surgical management and counseling of patients with unicoronal synostosis.

Outcome analysis for correction of single suture craniosynostosis using resorbable fixation.

A retrospective review was performed on 63 patients at Childrens Healthcare of Atlanta at Scottish Rite who underwent correction of single-suture craniosynostosis using a resorbable fixation system. Included in the series were 24 patients with metopic synostosis, 15 with sagittal synostosis, and 24 with unicoronal synostosis. The average age at operation was 22.7 months (range: 2.8 months-18 years), and mean follow-up time was 30.7 months (range: 7.1-10 years). Reoperation equal to or exceeding the magnitude of the original procedure occurred in 4.76% of the patients. This was comparable to the reoperation rate observed at our institution using traditional fixation systems. Minor complications related to the use of resorbable plates were also identified, and the final outcome for single-suture synostosis was favorable. Results suggest that resorbable plates and screws are as effective as titanium-based systems in the treatment of single-suture synostosis.

Plasticity of the endocranial base in nonsyndromic craniosynostosis.

Limited in vivo data exist on the dysmorphology of the cranial base in nonsyndromic craniosynostosis. Few studies have documented the effect of calvarial surgery for synostosis on endocranial morphology. Previous work has suggested that the dysmorphology of the endocranial base is diagnostically specific for metopic, sagittal, and unicoronal sutures. The purpose of this study was to further evaluate the endocranial base in infants with nonsyndromic craniosynostosis by testing the hypothesis that the dysmorphology is, to some degree, a secondary deformation rather than a primary malformation. Three questions were addressed: (1) Can individuals reliably identify affected suture-specific endocranial-base morphology using standard templates? (2) Does calvarial surgery in infancy for craniosynostosis affect the perception of endocranial-base morphology? and (3) Does calvarial surgery in infancy for nonsyndromic craniosynostosis normalize the endocranial base?In this study, three-dimensional volumetric reconstructions from archived computed tomography digital data were processed using the ANALYZE imaging software. Dysmorphology was assessed by nine independent, blinded skilled observers who reviewed two separate sets of images of endocranial bases. Both sets contained images from the same patients: one set contained preoperative images, and the other contained images of the endocranial base 1 year after calvarial surgery. Observers were asked to sort each set into four suture-specific diagnostic groups: normal, unicoronal, metopic, and sagittal. Each set contained 10 patients with unicoronal synostosis, 10 with metopic synostosis, 10 with sagittal synostosis, and four normal patients. Seventy-eight percent of the total number of preoperative images were correctly sorted into the suture-specific diagnostic group, whereas only 55 percent of the total number of postoperative images were correctly matched. With regard to the individual sutures, the results were as follows (data are presented as preoperative accuracy versus postoperative accuracy): metopic, 76 percent versus 44 percent; sagittal, 58 percent versus 34 percent; unicoronal, 100 percent versus 79 percent; and normal, 83 percent versus 72 percent. Although 36 of 306 total images per group (12 percent) actually represented normal patients, the observers called 72 of 306 normal (24 percent) in the preoperative set versus 110 of 306 normal (36 percent) in the postoperative set. In conclusion, (1) the endocranial dysmorphology of nonsyndromic craniosynostosis is recognizably specific to the affected suture; (2) calvarial surgery for nonsyndromic craniosynostosis normalizes the endocranial base qualitatively with regard to the diminished ability of raters to identify the primary pathology; and (3) the documented postoperative changes in endocranial base morphology after calvarial surgery for nonsyndromic craniosynostosis in infancy indicates that a major component of that dysmorphology is a secondary deformity rather than a primary malformation.

Perioperative transcranial Doppler US to evaluate intracranial compliance in young children undergoing craniosynostosis repair surgery.

To determine whether measurements with transcranial Doppler ultrasonography (US) of resistive indexes (RIs) of basal cerebral arteries with pressure provocation can be used to identify infants and children with craniosynostosis who have abnormal intracranial compliance and to study the effects of surgery on compliance. Transcranial Doppler US was performed through the temporal squama, fontanels, and existing skull defects prior to and immediately following cranioplasty. Twenty-four studies were performed in six patients with multisuture synostosis, and 61 studies were performed in 26 patients with single-suture synostosis. Study findings were compared with those of 23 control subjects and were characterized as normal or abnormal on the basis of age-specific normal criteria for RI. In multisuture synostosis, results of six of the nine preoperative transcranial Doppler US studies were abnormal. During postoperative follow-up, three recurrences requiring reoperation occurred, one of which was detected with abnormal transcranial Doppler US findings. In single-suture synostosis, results of seven of the 26 preoperative transcranial Doppler US studies were abnormal, and all occurred in young infants with sagittal and unicoronal synostosis. Immediate effects of surgery were variable. All patients with sagittal synostosis had a significant immediate postoperative increase in RI, which normalized during postoperative follow-up. There was no significant difference in RI between patients with successfully treated craniosynostosis and control subjects. Transcranial Doppler US can be used to identify patients with craniosynostosis with decreased intracranial compliance, and it is a suitable noninvasive test to monitor the effects of surgery on compliance.

Presurgical finite element analysis from routine computed tomography studies for craniofacial distraction: II. An engineering prediction model for gradual correction of asymmetric skull deformities.

Finite element analysis from routine computed tomography studies (CT/FEA) allows clinicians to predict the mechanical and anatomic consequences of specific distraction systems before human application. A realistic three-dimensional CT/FEA engineering model of an actual plagiocephalic infant with unicoronal synostosis was developed using 4215 parabolic triangular shell elements and intracranial pressure conditions ranging from 10 to 20 mmHg. The completed finite element analysis model was used to predict the anatomic outcome of multiaxial distraction delivered by hypothetical patterns of rod and node distraction units. The predictions for the various patterns of distraction units were also compared quantitatively with respect to force, stress, strain, and intracranial volume. Best anatomic corrections were achieved with bilateral patterns of distraction units that simultaneously elongated the ipsilateral cranium and shortened the contralateral cranium. Greatest strain levels were experienced within the osteotomy callus, greatest stress levels at the appliance anchorage sites, and the greatest rod force at the ipsilateral lower coronal position.

A rabbit model of human familial, nonsyndromic unicoronal suture synostosis. II. Intracranial contents, intracranial volume, and intracranial pressure.

This two-part study reviews data from a recently developed colony of New Zealand white rabbits with familial, nonsyndromic unilateral coronal suture synostosis, and this second part presents neuropathological findings and age-related changes in intracranial volume (ICV) and intracranial pressure (ICP) in 106 normal rabbits and 56 craniosynostotic rabbits from this colony. Brain morphology and anteroposterior length were described in 44 rabbit fetuses and perinates (27 normal; 17 synostosed). Middle meningeal artery patterns were qualitatively assessed from 2-D PCC MRI VENC scans and endocranial tracings from 15, 126-day-old rabbits (8 normal, 7 rabbits with unicoronal synostosis). Brain metabolism was evaluated by assessing 18F-FDG uptake with high-resolution PET scanning in 7, 25-day-old rabbits (3 normal, 4 with unicoronal or bicoronal synostosis). Intracranial contents and ICV were assessed using 3-D CT scanning of the skulls of 30 rabbits (20 normal,10 with unicoronal synostosis) at 42 and 126 days of age. Serial ICP data were collected from 66 rabbits (49 normal; 17 with unicoronal synostosis) at 25 and 42 days of age. ICP was assessed in the epidural space using a Codman NeuroMonitor microsensor transducer. Results revealed that cerebral cortex morphology was similar between normal and synostosed fetuses around the time of synostosis. Significantly (P<0.05) decreased A-P cerebral hemisphere growth rates and asymmetrical cortical remodeling were noted with increasing age in synostotic rabbits. In addition, rabbits with unicoronal suture synostosis exhibited asymmetrical middle meningeal artery patterns, decreased and asymmetrical brain metabolism, a "beaten-copper" intracranial appearance, significantly (P<0.05) decreased ICV, and significantly (P<0.01) elevated ICP compared with normal control rabbits. The advantages and disadvantages of these rabbits as a model for human familial, nonsyndromic unicoronal suture synostosis are discussed, especially in light of recent clinical neuropathological, ICV, and ICP findings recorded in human craniosynostotic studies.

A rabbit model of human familial, nonsyndromic unicoronal suture synostosis. I. Synostotic onset, pathology, and sutural growth patterns.

Poswillo has stated, "The more severe anomalies of the calvaria, such as plagiocephaly, Crouzon [syndrome], and Apert syndrome still defy explanation, in the absence of an appropriate animal system to study" (p. 207). This two-part study reviews data from a recently developed colony of New Zealand white rabbits with familial, nonsyndromic unilateral coronal suture synostosis. Part 1 presents pathological findings and compensatory sutural growth data from 109 normal rabbits and 82 craniosynostotic rabbits from this colony. Synostotic foci, onset, and progression were described in the calvariae from 102 staged (fetal days 21, 25, 27, 33; term = 30 days) fetuses (39 normal, 63 synostosed). Calvarial suture growth patterns from 10 to 126 days of age were assessed from serial radiographs obtained from 89 rabbits (70 normal rabbits and 19 rabbits with unicoronal suture synostosis) with amalgam bone marker implants. Perinatal results revealed that by fetal day 25 the synostotic focal point in synostotic rabbits consistently originated from the endocortical surface of the calvaria in the middle of the coronal suture at a presumed high-tension, interdigitating zone. Histological analysis revealed hyperostotic osteogenic fronts on the affected side compared with the unaffected side. Postnatal sutural growth data revealed a predictable pattern of plagiocephaly (contralateral coronal sutures growing more than ipsilateral sutures and ipsilateral frontonasal and anterior lambdoidal sutures growing more than contralateral sutures), which resulted in early cranial vault deformities and a double "S" shape torquing towards the affected side. The advantages and disadvantages of these rabbits as a model for human familial, nonsyndromic unicoronal suture synostosis are discussed, especially in light of recent cytokine and genetic findings from human craniosynostotic studies.

Identification of a genetic cause for isolated unilateral coronal synostosis: A unique mutation in the fibroblast growth factor receptor 3

To determine whether the autosomal dominant fibroblast growth factor receptor 3 (FGFR3) Pro250Arg mutation causes anterior plagiocephaly, patients with either apparently sporadic unicoronal synostosis ( N = 37) or other forms of anterior plagiocephaly ( N = 10) were studied for this mutation. Of 37 patients with unicoronal synostosis, 4 tested positive for the Pro250Arg mutation in FGFR3, and 33 were negative for this mutation. In three mutation positive patients with full parental studies, a parent with an extremely mild phenotype was found to carry the same mutation. None of the 6 patients with nonsynostotic plagiocephaly and none of the 4 patients with additional suture synostosis had the FGFR3 mutation. Because it is impossible to predict the FGFR3 Pro250Arg mutation status based on clinical examination alone, all patients with unicoronal synostosis should be tested for it. To assess their recurrence risk, all parents of mutation positive patients should be tested regardless of their clinical findings, because the phenotype can be extremely variable and without craniosynostosis. (J Pediatr 1998;132:714-6.)

Upper airway obstruction and raised intracranial pressure in children with craniosynostosis.

In children with craniosynostosis, raised intracranial pressure (ICP) and upper airway obstruction (UAO) are both common features. However, potential interactions between UAO and ICP during sleep are poorly understood. The aim of the present study was to compare the levels of ICP during sleep between a group of patients with syndromic craniosynostosis (with facial involvement and consequent UAO) and a group of control patients with isolated unicoronal synostosis (with no facial involvement and normal upper airways). Polygraphic cardiorespiratory sleep studies with continuous monitoring of ICP were performed during unsedated sleep in 13 children with syndromic craniosynostosis and 7 control patients with isolated unicoronal synostosis only. In the syndromic group, UAO was present in 11 out of 13 patients, with 8 out of 13 having frank obstructive sleep apnoea. In contrast, none of the control patients showed signs of UAO during sleep. There was no evidence of central apnoeas in any of the patients studied. Clinical histories taken from parents tended to underestimate the severity of the respiratory problems. Elevated ICP was seen in 10 of the 13 syndromic patients, with borderline raised ICP in the remaining three cases. In contrast, raised ICP was seen in only 3 of the 7 control patients, with borderline raised levels in 2 of the 7. For both patient groups, ICP was higher during active sleep compared to quiet sleep. Multiple regression analysis showed that ICP during active sleep was dependent upon disease severity (unicoronal/ multiple synostosis) and to the baseline ICP level during quiet sleep. Both raised ICP and airway obstruction were more apparent during active sleep. There was a significant correlation between severity of UAO and increased ICP in active sleep. We conclude that obstructive respiratory problems are frequent in the syndromic patients, and can be severe in a large proportion of cases; intracranial hypertension is also frequent in this group. Further studies are required to investigate the possibility of a causal relationship between upper airway obstruction and raised intracranial pressure.

Development of plagiocephaly in rabbits with unicoronal synostosis.

Human unicoronal synostosis results in plagiocephaly of the cranial vault due to predictable compensatory growth patterns of the contralateral coronal, sagittal, and ipsilateral squamosal sutures. The present study describes the development of plagiocephaly and tests compensatory growth predictions in a naturally occurring rabbit model of uncorrected unicoronal synostosis. Cranial vault and sutural growth data were collected from serial x-ray films in 70 normal rabbits and 19 rabbits with congenital unicoronal synostosis from 1.5 to 18 weeks of age. One-way analysis of variance results revealed that rabbits with unicoronal synostosis had significant (p < 0.05) growth inhibition at both coronal sutures and the contralateral frontonasal suture and a significantly wider (p < 0.05) cranial vault compared to controls. Paired Student's t-tests between affected and unaffected sides of the vault in rabbits with synostosis revealed significant (p < 0.05) asymmetry, with ipsilateral coronal sutures growing less than contralateral ones. Gross qualitative examination of the adult brains revealed severe asymmetry and anteroposterior reduction on the ipsilateral side. These results demonstrate that this congenital rabbit model effectively simulates human cranial vault growth predictions from unicoronal synostosis and produces a plagiocephalic morphology.

Mandibular dysmorphology in unicoronal synostosis and plagiocephaly without synostosis.

Patients with unicoronal synostosis (UCS) or plagiocephaly without synostosis (PWS) have distinctive skull dysmorphologies. Associated mandibular dymorphologies have been suspected but not quantified. This study was performed to test the hypothesis that discrete mandibular dysmorphology exists in both UCS and PWS. All patients at a tertiary referral center at a medical school-affiliated children's hospital with confirmed diagnosis of UCS or PWS with adequate pretreatment CT data were included in the study population, which population was comprised of 20 UCS, 23 PWS, and 8 normal infants. Each patient had a head CT scan using 2-mm slices. 3-D images were created using Analyze, a biomedical imaging program. The mandibles were isolated, and the coordinates of 8 landmarks were sampled from each mandible by a single investigator: a single volume value was measured, and 9 linear distances and 4 angles were calculated. Corresponding measurements from each hemimandible were expressed as ratios of ipsilateral/contralateral side. In UCS, the affected side was defined as the side ipsilateral to the synostosis; In PWS, the affected side was defined as the side ipsilateral to the occipital flattening. The results from both groups were t tested for statistical significance. For UCS, statistically significant (p < .001) findings included: ipsilateral hemimandibular volume 5% smaller than contralateral; affected hemimandibular body length 1.9% shorter; affected gonial angle 2.6% more acute; affected coronoid process tilted anteriorly 2.5%; and distances from condylion and tip of the coronoid process to the chin landmarks 4% shorter on the affected side. For PWS, significant findings included: affected hemimandibular volume 3.8% larger; ramal height 3.5% shorter; mandibular body length 3% longer; and coronoid process tilted anteriorly by 2.3% on the affected side. In the UCS/PWS comparison, findings included: affected hemimandibular volume in UCS 8.7% less; affected gonial angle in UCS 3% more acute; affected mandibular corpus length in UCS 5% shorter; distances from the condylion and the tip of the coronoid process to the chin landmarks 4% shorter on the affected side in UCS. The hypothesized presence of diagnosis specific mandibular dysmorphology in UCS and PWS is confirmed. This analysis forms the baseline for study of the effects of unperturbed growth or therapeutic interventions upon the dentoskeletal dysmorphology of these anomalies.

Mandibular Dysmorphology in Unicoronal Synostosis and Plagiocephaly without Synostosis

Mandibular Dysmorphology in Unicoronal Synostosis and Plagiocephaly without Synostosis

A Prospective Study of the Relationship Between Strabismus and Head Posture in Patients with Frontal Plagiocephaly

A prospective study was performed on 16 unoperated patients with frontal plagiocephaly to characterize the relationship between strabismus and abnormal head posture. Serial eye examinations were performed preoperatively and for 24 to 46 months following fronto-orbital advancement. In 14 patients (88 percent), preoperative clinical examination and CT scan indicated coronal plagiocephaly (synostotic); unicoronal synostosis was documented during fronto-orbital advancement in all these patients. Ten patients had abnormal head posture on preoperative examination, 9 of whom had strabismus at some time during the study. These 9 patients all had unicoronal synostosis with ipsilateral strabismus and a contralateral head tilt. All had eye muscle findings consistent with superior oblique paresis, although in 2 patients these signs first developed following fronto-orbital advancement. Strabismus resolved spontaneously in 2 patients between 2 and 8 months following fronto-orbital advancement; the remaining 7 patients underwent extraocular muscle surgery following fronto-orbital advancement, with early resolution of strabismus in all cases. The head tilt resolved or improved significantly in all 9 patients following resolution of the strabismus. Two patients had recurrent superior oblique paresis following surgical correction, necessitating secondary strabismus surgery. The present study indicates that extraocular muscle dysfunction is the major cause of abnormal head posture in patients with coronal plagiocephaly and emphasizes the need for long-term ophthalmologic surveillance in these patients.

Plagiocephaly: differential diagnosis based on endocranial morphology.

Plagiocephaly is a descriptive term that connotes an asymmetrically oblique or twisted head. Such cranial dysmorphology has a number of etiologies, the most common of which are unicoronal synostosis, unilambdoid synostosis, and plagiocephaly without synostosis. Use of the term plagiocephaly in the literature is often ambiguous in that at times it is used inclusively for all etiologies while at other times it is used exclusively as a synonym for unicoronal synostosis. Although differentiation by physical examination among unicoronal synostosis, unilambdoid synostosis, and plagiocephaly without synostosis usually is possible for an experienced observer, inexperienced observers often have difficulty making an anatomically accurate diagnosis even with the assistance of conventional skull radiographs. High-resolution CT scans, including three-dimensional osseous surface re-formations, have become a standard element in the evaluation of craniofacial anomalies in many centers. We hypothesized that the three major etiologies of plagiocephaly could be unambiguously differentiated by means of endocranial three-dimensional CT osseous surface re-formations. Archival pretreatment CT data on 15 unicoronal synostosis, 4 unilambdoid synostosis, and 15 plagiocephaly without synostosis patients were reviewed to define, qualitatively and quantitatively, the characteristics of the endocranial base morphologies for each group; in addition to visual dysmorphology specific to each group, there was a statistically significant difference in the angle of deviation from the midlines of the anterior and posterior cranial fossae among unicoronal synostosis, unilambdoid synostosis, and plagiocephaly without synostosis. Four radiologists experienced in reading images of craniofacial anomalies were oriented to the group characteristics and then instructed to perform differential diagnosis for each of the 34 patients using only the endocranial three-dimensional CT images. The raters were blind to all other clinical and diagnostic information. The raters correctly diagnosed unicoronal synostosis. Errors were made in differentiation of unilambdoid synostosis and plagiocephaly without synostosis. These errors resulted from the raters' reliance on image inspection rather than quantitation of anteroposterior fossae midline angulation. Such quantitation unambiguously differentiated between unilambdoid synostosis and plagiocephaly without synostosis in the "error" cases. The endocranial base dysmorphology of patients with plagiocephaly is etiology-specific for unicoronal synostosis, unilambdoid synostosis, and plagiocephaly without synostosis. Three-dimensional CT endocranial base images can assist differential diagnosis of plagiocephaly.

Genetic study of nonsyndromic coronal craniosynostosis

From a series of 1265 individuals with different craniosynostoses hospitalized between 1976 and 1993, 260 probands with nonsyndromic unilateral (181) or bilateral (79) coronal synostosis were analysed. The prevalence of craniosynostoses was estimated as 1 in 2100 children. In the group of coronal synostosis, family history was obtained on 192 probands in 180 pedigrees. The male:female ratio was 1:2. The average paternal age was 32.7 +/- 6.4 years, which is significantly higher than normal. In 26 of the 180 pedigrees, a high degree of familial aggregation was observed, giving a 14.4% figure of familial cases. The bicoronal synostoses were significantly more often familial than the unicoronal synostoses. Segregation analysis of these families leads to the conclusion that coronal synostosis is transmitted as a dominant disorder with 0.60 penetrance and 61% of sporadic cases.