Identification of skull base sutures and craniofacial anomalies in children with craniosynostosis: utility of multidetector CT

Impact of Sonic Hedgehog-dependent sphenoid bone defect on craniofacial growth

OBJECTIVES

The main objective of this study was to evaluate how an apparently minor anomaly of the sphenoid bone, observed in a haploinsufficient mouse model for Sonic Hedgehog (Shh), affects the growth of the adult craniofacial region. This study aims to provide valuable information to orthodontists when making decisions regarding individuals carrying SHH mutation.

MATERIALS AND METHODS

The skulls of embryonic, juvenile and adult mice of two genotypes (Shh heterozygous and wild type) were examined and measured using landmark-based linear dimensions. Additionally, we analysed the clinical characteristics of a group of patients and their relatives with SHH gene mutations.

RESULTS

In the viable Shh+/ - mouse model, bred on a C57BL/6J background, we noted the presence of a persistent foramen at the midline of the basisphenoid bone. This particular anomaly was attributed to the existence of an ectopic pituitary gland. We discovered that this anomaly led to premature closure of the intrasphenoidal synchondrosis and contributed to craniofacial deformities in adult mice, including a longitudinally shortened skull base. This developmental anomaly is reminiscent of that commonly observed in human holoprosencephaly, a disorder resulting from a deficiency in SHH activity. However, sphenoid morphogenesis is not currently monitored in individuals carrying SHH mutations.

CONCLUSION

Haploinsufficiency of Shh leads to isolated craniofacial skeletal hypoplasia in adult mouse. This finding highlights the importance of radiographic monitoring of the skull base in all individuals with SHH gene mutations.

Association of cranial base suture/synchondrosis fusion with severity of increased intracranial pressure in Crouzon syndrome

This study investigated how the fusion states of the cranial base is related to the degree of increased intracranial pressure (ICP) in patients with Crouzon syndrome. This retrospective cohort study enrolled patients who were diagnosed with Crouzon syndrome between May 2007 and April 2022. We categorized the patients into three groups: A, B, and C, according to the severity of increased ICP and the number of cranial vault remodeling procedures for corrective operation. The preoperative fusion states of the cranial base sutures/synchondroses were examined using facial bone computed tomography and compared between groups. Overall, 22 patients were included in Groups A, B, and C, including 8, 7, and 7 patients, respectively. The preoperative average grades of the total cranial base suture/synchondrosis fusion appeared to significantly increase with severity, except for the frontoethmoidal suture, which showed the opposite tendency. In the subgroup analysis, frontosphenoidal, sphenoparietal, sphenosquamosal, parietomastoid, and occipitomastoid suture and petro-occipital synchondrosis were associated with earlier fusion in the more severe group. Premature closure of the cranial base sutures/synchodroses seems to be associated with increased ICP severity in patients with Crouzon syndrome. Precise evaluation of minor sutures/synchondroses at the first visit might help build subsequent operative plans and predict disease prognosis.

Minor Suture Fusion is Associated With Chiari Malformation in Nonsyndromic Craniosynostosis

Here, we focused on the association between minor suture fusion and Chiari malformation (CM) occurrence in nonsyndromic craniosynostosis (NSC), and evaluated how the minor suture affects the posterior cranial fossa by measuring the posterior fossa deflection angle (PFA). In this retrospective study, the clinical records of 137 patients who underwent surgery for NSC at Aichi Children's Health and Medical Center between April 2010 and May 2022 were analyzed. Clinical data from Aichi Developmental Disability Center Central Hospital was collected for 23 patients as the external validation set. Among the 137 patients, 123 were diagnosed with NSC and the remaining 14 with syndromic craniosynostosis. Of the 123 NSC patients, 23 patients presented with CM. Multivariate analysis showed that occipito-mastoid fusion was the only significant risk factor for CM ( P =0.0218). Within the NSC group, CM patients had a significantly increased PFA (6.33±8.10 deg) compared with those without CM (2.76±3.29 deg, P =0.0487). Nonsyndromic craniosynostosis patients with occipito-mastoid suture fusion had a significantly increased PFA (6.50±7.60 deg) compared with those without occipito-mastoid fusion (2.60±3.23 deg, P =0.0164). In the validation cohort, occipito-mastoid suture fusion was validated as an independent risk factor for CM in univariate analysis. Minor suture fusion may cause CM associated with NSC. Chiari malformation could develop due to an increased PFA due to minor suture fusion, which causes growth disturbance in the affected side and compensatory dilation in the contralateral side within the posterior cranial fossa.

Ultrasonography as first line imaging for the diagnosis of positional plagiocephaly

BACKGROUND

In the last years, numerous studies evaluated different tools for the diagnosis of positional plagiocephaly (PP). The purpose of this study was to evaluate ultrasonography (US) as a first line screening test of lambdoid sutural patency in child with PP and to compare our results with the literature.

METHODS

All consecutive patients who referred to our Institute from January 2016 to October 2017 with the suspicion of PP, were included in the study and performed US examination of the lambdoid sutures. A 3-6-month clinical follow-up was performed by a pediatric neurosurgeon or a pediatrician to confirm the diagnosis of PP.

RESULTS

Thirty-five children performed US examination and in all cases the diagnosis of PP was confirmed. No cases of anticipated suture fusion were examined during this period. The concordance between US findings and clinical exam follow-up was 100%.

CONCLUSIONS

Ultrasonography of the lambdoid sutures represents an ideal first-line screening test and reliable alternative to other diagnostic techniques for lambdoid sutural patency in child with PP, being radiation free, fast and cheap.

Postoperative computed tomography imaging of pediatric patients with craniosynostosis: radiation dose and image quality comparison between multi-slice computed tomography and O-arm cone-beam computed tomography

BACKGROUND

When postoperative multi-slice computed tomography (MSCT) imaging of patients with craniosynostosis is used, it is usually performed a few days after surgery in a radiology department. This requires additional anesthesia for the patient. Recently, intraoperative mobile cone-beam CT (CBCT) devices have gained popularity for orthopedic and neurosurgical procedures, which allows postoperative CT imaging in the operating room.

OBJECTIVE

This single-center retrospective study compared radiation dose and image quality of postoperative imaging performed using conventional MSCT scanners and O-arm CBCT.

MATERIALS AND METHODS

A total of 104 pediatric syndromic and non-syndromic patients who were operated on because of single- or multiple-suture craniosynostosis were included in this study. The mean volumetric CT dose index (CTDIvol) and dose-length product (DLP) values of optimized craniosynostosis CT examinations (58 MSCT and 46 CBCT) were compared. Two surgeons evaluated the subjective image quality.

RESULTS

CBCT resulted in significantly lower CTDIvol (up to 14%) and DLP (up to 33%) compared to MSCT. Multi-slice CT image quality was considered superior to CBCT scans. However, all scans were considered to be of sufficient quality for diagnosis.

CONCLUSION

The O-arm device allowed for an immediate postoperative CBCT examination in the operating theater using the same anesthesia induction. Radiation exposure was lower in CBCT compared to MSCT scans, thus further encouraging the use of O-arms. Cone-beam CT imaging with an O-arm is a feasible method for postoperative craniosynostosis imaging, yielding less anesthesia to patients, lower health costs and the possibility to immediately evaluate results of the surgical operation.

Fusion of Lateral Calvarial Sutures on Volume-Rendered Computed Tomography Reconstructions in Patients With Known Craniosynostosis

INTRODUCTION

After treating a child with familial sagittal craniosynostosis, clinocephaly, and bilateral parietomastoid/posterior squamosal suture fusion, the authors wondered if major-suture synostosis and clinocephaly were associated with abnormal fusion of minor lateral calvarial sutures.

METHODS

The authors reviewed all preoperative volume-rendered head computed tomography reconstructions performed for craniosynostosis at their institution from 2010 through 2014 and determined whether the sphenoparietal, squamosal, and parietomastoid sutures were open, partially fused, or fused. The authors determined whether any sutures were abnormally fused based upon a previous study from their center, in which abnormal fusion was defined as either 1 of 3 abnormal fusion patterns or abnormally-early fusion. The authors then determined the rate of abnormal fusion of these sutures and whether abnormal fusion was associated with (1) major-suture craniosynostosis, (2) type of craniosynostosis (sutures involved; single-suture versus multisuture; syndromic versus nonsyndromic), and (3) clinocephaly.

RESULTS

In 97 included children, minor lateral sutures were abnormally fused in 8, or 8.2%, which was significantly higher than in children without craniosynostosis from our earlier study. Abnormal minor lateral suture fusion was not associated with the type of single-suture synostosis or with multisuture synostosis but was associated with syndromic synostosis. Four of 8 children with abnormal minor lateral suture fusion had multisuture synostosis and 6 had syndromic synostosis. Lateral sutures were abnormally fused in 1 of 4 subjects with clinocephaly, which was not significant.

CONCLUSION

Abnormal minor lateral calvarial suture fusion is significantly associated with major-suture craniosynostosis, especially syndromic synostosis.

CT-based radiomics modeling for skull dysmorphology severity and surgical outcome prediction in children with isolated sagittal synostosis: a hypothesis-generating study

Purpose

To investigate the potentialities of radiomic analysis and develop radiomic models to predict the skull dysmorphology severity and post-surgical outcome in children with isolated sagittal synostosis (ISS).

Materials and methods

Preoperative high-resolution CT scans of infants with ISS treated with surgical correction were retrospectively reviewed. The sagittal suture (ROI_entire) and its sections (ROI_anterior/central/posterior) were segmented. Radiomic features extracted from ROI_entire were correlated to the scaphocephalic severity, while radiomic features extracted from ROI_anterior/central/posterior were correlated to the post-surgical outcome. Logistic regression models were built from selected radiomic features and validated to predict the scaphocephalic severity and post-surgical outcome.

Results

A total of 105 patients were enrolled in this study. The kurtosis was obtained from the feature selection process for both scaphocephalic severity and post-surgical outcome prediction. The model predicting the scaphocephalic severity had an area under the curve (AUC) of the receiver operating characteristic of 0.71 and a positive predictive value of 0.83 for the testing set. The model built for the post-surgical outcome showed an AUC (95% CI) of 0.75 (0.61;0.88) and a negative predictive value (95% CI) of 0.95 (0.84;0.99).

Conclusion

Our results suggest that radiomics could be useful in quantifying tissue microarchitecture along the mid-suture space and potentially provide relevant biological information about the sutural ossification processes to predict the onset of skull deformities and stratify post-surgical outcome.

Morphology of the Occipital Bones and Foramen Magnum Resulting From Premature Minor Suture Fusion in Crouzon Syndrome

To identify skull-base growth patterns in Crouzon syndrome, we hypothesized premature minor suture fusion restricts occipital bone development, secondarily limiting foramen magnum expansion.

Skull-base suture closure degree and cephalometric measurements were retrospectively studied using preoperative computed tomography (CT) scans and multiple linear regression analysis.

Evaluation of multi-institutional CT images and 3D reconstructions from Wake Forest's Craniofacial Imaging Database (WFCID).

Sixty preoperative patients with Crouzon syndrome under 12 years-old were selected from WFCID. The control group included 60 age- and sex-matched patients without craniosynostosis or prior craniofacial surgery.

None.

2D and 3D cephalometric measurements.

3D volumetric evaluation of the basioccipital, exo-occipital, and supraoccipital bones revealed decreased growth in Crouzon syndrome, attributed solely to premature minor suture fusion. Spheno-occipital (β = -398.75; P < .05) and petrous-occipital (β = -727.5; P < .001) suture fusion reduced growth of the basioccipital bone; lambdoid suture (β = -14 723.1; P < .001) and occipitomastoid synchondrosis (β = -16 419.3; P < .001) fusion reduced growth of the supraoccipital bone; and petrous-occipital suture (β = -673.3; P < .001), anterior intraoccipital synchondrosis (β = -368.47; P < .05), and posterior intraoccipital synchondrosis (β = -6261.42; P < .01) fusion reduced growth of the exo-occipital bone. Foramen magnum morphology is restricted in Crouzon syndrome but not directly caused by early suture fusion.

Premature minor suture fusion restricts the volume of developing occipital bones providing a plausible mechanism for observed foramen magnum anomalies.

Pediatric craniosynostosis computed tomography: an institutional experience in reducing radiation dose while maintaining diagnostic image quality

BACKGROUND

Children with craniosynostosis may undergo multiple computed tomography (CT) examinations for diagnosis and post-treatment follow-up, resulting in cumulative radiation exposure.

OBJECTIVE

To reduce the risks associated with radiation exposure, we evaluated the compliance, radiation dose reduction and clinical image quality of a lower-dose CT protocol for pediatric craniosynostosis implemented at our institution.

MATERIALS AND METHODS

The standard of care at our institution was modified to replace pediatric head CT protocols with a lower-dose CT protocol utilizing 100 kV, 5 mAs and iterative reconstruction. Study-ordered, protocol-utilized and radiation-dose indices were collected for studies performed with routine pediatric brain protocols (n=22) and with the lower-dose CT protocol (n=135). Two pediatric neuroradiologists evaluated image quality in a subset (n=50) of the lower-dose CT studies by scoring visualization of cranial structures, confidence of diagnosis and the need for more radiation dose.

RESULTS

During the 30-month period, the lower-dose CT protocol had high compliance, with 2/137 studies performed with routine brain protocols. With the lower-dose CT protocol, volume CT dose index (CTDI_vol) was 1.1 mGy for all patients (0-9 years old) and effective dose ranged from 0.06 to 0.22 mSv, comparable to a 4-view skull radiography examination. CTDI_vol was reduced by 98% and effective dose was reduced up to 67-fold. Confidence in diagnosing craniosynostosis was high and more radiation dose was considered unnecessary in all studies (n=50) by both radiologists.

CONCLUSION

Replacing the routine pediatric brain CT protocol with a lower-dose CT craniosynostosis protocol substantially reduced radiation exposure without compromising image quality or diagnostic confidence.

Physiologic Timeline of Cranial-Base Suture and Synchondrosis Closure

BACKGROUND

Fusion of cranial-base sutures/synchondroses presents a clinical conundrum, given their often unclear "normal" timing of closure. This study investigates the physiologic fusion timelines of cranial-base sutures/synchondroses.

METHODS

Twenty-three age intervals were analyzed in subjects aged 0 to 18 years. For each age interval, 10 head computed tomographic scans of healthy subjects were assessed. Thirteen cranial-base sutures/synchondroses were evaluated for patency. Partial closure in greater than or equal to 50 percent of subjects and complete bilateral closure in less than 50 percent of subjects defined the fusion "midpoint." Factor analysis identified clusters of related fusion patterns.

RESULTS

Two hundred thirty scans met inclusion criteria. The sutures' fusion midpoints and completion ages, respectively, were as follows: frontoethmoidal, 0 to 2 months and 4 years; frontosphenoidal, 6 to 8 months and 12 years; and sphenoparietal, 6 to 8 months and 4 years. Sphenosquamosal, sphenopetrosal, parietosquamosal, and parietomastoid sutures reached the midpoint at 6 to 8 months, 8 years, 9 to 11 months, and 12 years, respectively, but rarely completed fusion. The occipitomastoid suture partially closed in less than or equal to 30 percent of subjects. The synchondroses' fusion midpoints and completion ages, respectively, were as follows: sphenoethmoidal, 3 to 5 months and 5 years; spheno-occipital, 9 years and 17 years; anterior intraoccipital, 4 years and 10 years; and posterior intraoccipital, 18 to 23 months and 4 years. The petro-occipital synchondrosis reached the midpoint at 11 years and completely fused in less than 50 percent of subjects. Order of fusion of the sutures, but not the synchondroses, followed the anterior-to-posterior direction. Factor analysis suggested three separate fusion patterns.

CONCLUSIONS

The fusion timelines of cranial-base sutures/synchondroses may help providers interpret computed tomographic data of patients with head-shape abnormalities. Future work should elucidate the mechanisms and sequelae of cranial-base suture fusion that deviates from normal timelines.

Venous anomalies in hypoplastic posterior fossa: unsolved questions

INTRODUCTION

Anomalous intracranial venous anatomy is described in patients with syndromic craniosynostosis and is of significant importance when it comes to surgical morbidity. However, it is still controversial its origin, type of circulation in each syndrome, how it behaves over time, when it can be interrupted and wether it needs to be studied. The purpose of this paper is to discuss these issues by reviewing the literature.

METHODS

A literature search was performed using the PubMed database with a focus on papers including detailed descriptions of the venous outflow in complex and syndromic craniosynostosis. Search details used were the following: ("veins"[MeSH Terms] OR "veins"[All Fields] OR "venous"[All Fields]) AND ("abnormalities"[Subheading] OR "abnormalities"[All Fields] OR "anomalies"[All Fields]) AND syndromic[All Fields] AND ("craniosynostoses" [MeSH Terms] OR "craniosynostoses"[All Fields] OR "craniosynostosis"[All Fields]). Studies that exposed details of venous anomalies found in syndromic or complex craniosynostosis were selected.

RESULTS

Of a total of 211 articles found, 11 were selected for this review. Of these, 5 were case reports, 5 retrospective studies, and only 1 prospective study. From the 6 series of cases presented, 5 discussed the relationship between jugular foramen stenosis (JFS) and collateral venous drainage. The authors discuss data from the literature for each leading question presented: 1-collateral circulation: is it an intrinsic trouble, a consequence of stenosis of the cranial base foramina or related to raised intracranial pressure (ICP)?; 2-what venous anomalies should we search for, and what is the best exam to study them?; 3-collateral circulation changes with time?; 4-can neurosurgeons interrupt the collateral circulation?; 5-should we study all complex types of craniosynostosis?

CONCLUSION

The importance of the study of the venous outflow in patients with complex craniosynostosis is evident in the literature. The real relationship between intracranial hypertension, hypoplastic skull base foramen, Chiari I malformation, hydrocephalus, and venous collateral circulation remains unknown. Prospective studies focusing on molecular biology analysis will possibly solve all of these leading questions.

Computer tomography-based quantitative analysis of the orbital proptosis severity in infants with syndromic craniosynostosis: case-control study

PURPOSE

Evaluation of orbital proptosis and sutural synostosis pattern along the coronal ring in craniofaciosynostosis patients with or without fibroblastic growth factor receptor 2 (FGFR2) mutation.

METHODS

High-resolution computer tomography was used to assess, in children with or without FGFR2 mutation, the early synostotic involvement of the "major" and "minor" sutures/synchondroses of the coronal arch along with the following orbital parameters: interorbital angle, bone orbital cavity volume, globe volume, ventral globe volume, ventral globe index.

RESULTS

Infants with FGFR2 mutation showed an increased number of closed minor sutures/synchondroses along the posterior coronal branch while both groups showed a comparable synostotic involvement of the minor sutures of the anterior coronal branch. FGFR2 infants with posterior coronal branch synostotic involvement showed a higher degree of proptosis due to both reduced bony cavity volume and increased globe volume (p<0.05).

CONCLUSIONS

Our data show that FGFR2 mutation together with posterior coronal branch synostotic involvement has a synergic effect in causing a more severe degree of orbital proptosis.

A comparison of 2- and 3-dimensional mandibular superimposition techniques against Björk's structural superimposition method

INTRODUCTION

The purpose of this research was to compare mandibular growth rotation relative to the cranial base in different vertical facial patterns on the basis of multiple 2-dimensional (2D) and 3-dimensional (3D) superimposition methods.

METHODS

Cone-beam computed tomography (CBCT) images taken at a mean interval of 54.8 ± 16.8 months were assessed from a sample of 70 growing patients. Three mandibular superimposition methods were compared against Björk's structural method: (1) a 2D landmark method (2D-M1), (2) a voxel-based 3D method based on a previously reported method (3D-M1), and (3) a voxel-based 3D method incorporating symphyseal structures as references (3D-M2). After superimposition, the relative change in cranial base lines as depicted in sagittal views were measured for true mandibular rotation. Agreement between methods was assessed with Lin's concordance correlation coefficient, Bland-Altman's limits of agreement, and the Bradley-Blackwood test.

RESULTS

Lin's concordance correlation coefficients ranged between 0.924 for the 2D-M1 method, 0.695 for the 3D-M1 method, and 0.965 for the 3D-M2 method. Bland-Altman limits of agreement were wide for all but the 3D-M2 method. Finally, the Bradley-Blackwood test of equality of means and variances was significant in all except the 3D-M2 method.

CONCLUSIONS

For time intervals between CBCT volume acquisitions >3 years, the use of the 2D-M1 and 3D-M1 methods is not recommended. There was a high concordance between the 3D-M2 method and Björk's structural method when assessing mandibular growth rotation using relative changes in cranial base lines. The high concordance was displayed across all vertical facial types and for all time differences between first and second CBCT data acquisitions.

Severe Cloverleaf Skull Deformity in c.1061C>G (p.Ser354Cys) Mutated Fibroblast Growth Factor Receptor 2 Gene in Crouzon Syndrome

ABSTRACT

Cloverleaf skull deformity (CSD), or Kleeblattschädel, is a condition with severe and unpatterned multisuture craniosynostosis, resulting in a trilobar-shaped skull. This deformity mainly comprises a cranio-orbito-facial malformation that leads to a spectrum of multidisciplinary issues. Several syndromes are associated with CSD, such as Crouzon syndrome (CS). Here, we report the case of an infant with CS and the pathogenic c.1061C>G (p.Ser354Cys) variant of the fibroblast growth factor receptor 2 (FGFR2) gene. The child presented with the severe form of CSD despite having a normal, mid-trimester, sonographic scan.

Squamous suture obliteration: frequency and investigation of the associated skull morphology

This study aimed to investigate the frequency of squamous suture (SqS) obliteration, to estimate the involvement of the major calvarial sutures and those surrounding the temporal squama, and to inspect the neuro- and basicranium for deformities. A series of 211 dry skulls of contemporary adult males were macroscopically observed. The skulls with closed SqS were scanned using an industrial µCT system. Digital morphometry of the skulls with obliterated SqS was performed by recording the 3D coordinates of anatomic landmarks and calculation of linear distances, angles and indices. Obliteration of SqS was observed in 3 (1.42%) skulls. One skull showed bilateral SqS obliteration. The other two cases were unilateral, one right-sided and one left-sided. SqS obliteration seems to be co-ordinated with the closure of the parietomastoid suture, partially related to the closure of the occipitomastoid, sphenoparietal and sphenofrontal sutures, and independent from the closure of the sphenosquamosal suture and the major calvarial sutures. No severe disproportions in the skull configuration were observed in the three investigated cases. The major differences in the complimentary hemicrania concern the parietal and occipital parts of the skull vault. Dorsum sellae erosion, an indicator for raised intracranial pressure, was observed in all three cases.

A systematic quantitative morpho-volumetric analysis in infants with sagittal craniosynostosis and relationship with the severity of scaphocephalic deformity

PURPOSE

Among patients with isolated sagittal synostosis (ISS), the head shape varies considerably in relation to the severity of the abnormality. This study aimed to quantify skull base morphometry and intracranial volume to investigate their relationships with the severity of scaphocephaly.

METHODS

We studied 66 infants with ISS identifying three groups according to the morphological severity of cranial deformity (group I: mild deformity; group II: moderate deformity; group III: severe deformity), by combining two scaphocephaly severity indices as descriptors of the relation of three morphological measurements (length, width and height) We perform a quantitative analysis using high-resolution CT images calculating following parameters: cranial fossae dimensions, supratentorial (ICV) and infratentorial (PCFV) cranial volume, supratentorial (WBV) and infratentorial (PCFBV) brain volume, ICV/WBV, PCFV/PCFBV, supratentorial and infratentorial cerebrospinal fluid (CSF).

RESULTS

In all subgroups, anterior and middle skull base lengths were increased, while posterior hemifossae lengths were unchanged. In mild subgroup, ICV/WBV was significantly different and ICV, WBV and CSF supratentorial volume increased (p < 0.05). In moderate and severe subgroups, FCPV/FCPBV was significantly different and CSF infratentorial volume was reduced (p < 0.05); FCPBV was increased only in the severe subgroup (p < 0.05).

CONCLUSION

This morpho-volumetric study provides new insights in understanding the compensatory changes occurring in infants at different stages of scaphocephaly severity. In particular, our study suggests that patients with severe deformity might have an earlier depletion of reserve mechanisms with a reduced compliance of the overall skull during encephalic growth and these patients might require early surgical cranial expansion.

CT Imaging Findings after Craniosynostosis Reconstructive Surgery

Several surgical options are available for treating the different types of craniosynostosis, including fronto-orbital advancement and remodeling, total or subtotal cranial vault remodeling, barrel stave osteotomy with cranial remodeling, endoscopic suturectomy, monobloc advancement and cranioplasty, and revision cranioplasty. High-resolution, low-dose CT with 3D reconstructed images and volumetric analysis can be useful for evaluating the craniofacial skeleton following surgery. The various types of craniosynostosis surgery and corresponding imaging findings are reviewed in this article.

Quantitative approach to the posterior cranial fossa and craniocervical junction in asymptomatic children with achondroplasia

PURPOSE

We propose an magnetic resonance imaging (MRI)-based quantitative morphovolumetric approach to the posterior cranial fossa (PCF) and craniocervical junction (CCJ) changes in achondroplastic patients investigating possible associations with ventriculomegaly and medullary compression.

METHODS

We analyzed MRI of 13 achondroplastic children not treated by surgery. 3D FSPGR T1-weighted images were used to analyze (1) PCF synchondroses; (2) PCF volume (PCFV), PCF brain volume (PCFBV), PCFV/PCFBV ratio, cerebellar volume, cerebrospinal fluid (CSF) spaces volume, and IV ventricle volume; (3) PCF (clivus, supraocciput, exocciput lengths, tentorial angle) and CCJ (AP and LL diameters of foramen magnum (FM)) morphometry; (4) measurements of FM and jugular foramina (JF) areas; and (5) supratentorial ventricular volume.

RESULTS

All patients showed synostosis of spheno-occipital synchondroses, eight showed synostosis of intra-occipital synchondroses, nine showed CCJ impingement on the cervical cord but only three had cervical myelopathy. Compared to controls, clivus and exocciput lengths, LL and AP diameters of FM, FM area and JF area were significantly reduced, supraocciput length, tentorial angle, PCFV, PCFBV, cerebellar volume, supratentorial ventricular system volume were significantly increased. A correlation was found between clivus length and supratentorial ventricular volume, premature closure of intra-occipital synchondroses and FM area while a trend was found between FM area and supraocciput length.

CONCLUSION

Our analysis demonstrates a relationship between the shortening of the clivus and the ventriculomegaly. On the other hand the premature closure of PCF synchondroses, the shape, and the growth direction of supraocciput bone contribute to reduce the FM area, causing in some patients medullary compression.

Effectiveness of screening for craniosynostosis with ultrasound: a retrospective review

BACKGROUND

Minimizing the ionizing radiation dose to children is fundamental to pediatric radiology. The most widely accepted imaging examination for evaluating craniosynostosis is computed tomography (CT) of the head, an examination that involves ionizing radiation.

OBJECTIVE

To determine if sonography of the cranial sutures is an adequate screening examination for the diagnosis of craniosynostosis in patients with abnormal skull shape.

MATERIALS AND METHODS

A retrospective review of all cranial suture ultrasound (US) examinations performed during the course of a 3-year period (July 2012 - September 2015) was undertaken. Results were compared with clinical follow-up and/or head CT to evaluate the accuracy of this modality as a screening tool to determine the presence or absence of craniosynostosis. Fifty-two sonographic exams were adequate for inclusion.

RESULTS

Forty-five of the examinations did not reveal synostosis. In each of these instances, follow-up physical exam findings and/or CT imaging confirmed that no abnormal premature suture closure was present. US findings demonstrated synostosis in seven cases. CT exam or operative reports of these cases confirmed all seven findings of premature suture closure. Statistical analysis demonstrated a sensitivity of 100% (95% confidence interval [CI]: 56.1-100.0%), a specificity of 100% (95% CI: 90.2-100.0%), and a negative predictive value of 100% (95% CI: 90.2-100.0%).

CONCLUSION

Cranial US is a reliable screening tool to rule out craniosynostosis in patients with abnormal head shape.

Quantitative analysis of craniofacial dysmorphology in infants with anterior synostotic plagiocephaly

PURPOSE

The study aimed to identify premature synostosis of "major" and "minor" sutures of the coronal sutural arch and splanchnocranium sutures to evaluate the relationship between craniofacial dysmorphology and the sutural pattern in children with anterior plagiocephaly.

METHODS

A quantitative analysis of the skull base and facial changes was performed on preoperative high-resolution CT images in 18 children with anterior synostotic plagiocephaly and compared with imaging findings in 18 age-matched healthy subjects.

RESULTS

All patients had patent splanchnocranium sutures. Fifteen out of 18 children showed early and isolated synostosis of the unicoronal suture (the major suture of the coronal ring) and were classified in groups II and III according to the classification scheme of anterior synostotic plagiocephaly based on the severity of craniofacial dysmorphology. Premature fusion of the unilateral coronal suture in groups II and III caused a marked asymmetry and reduced growth of the anterior and middle fossae on the synostotic side and a secondary varying severity in terms of asymmetric growth of the facial complex. Although both groups showed anterior displacement of the mandibular articulation on the synostotic side, group II showed only maxillary asymmetry, while group III showed maxillary and mandibular asymmetry.

CONCLUSIONS

In anterior synostotic plagiocephaly, the severity of skull base changes and asymmetric growth of the facial complex is not caused by skull base sutural synostotic involvement but is probably related to the different timing of unilateral coronal suture closure.

Craniosynostosis : Updates in Radiologic Diagnosis

The purpose of this article is to review imaging findings and to discuss the optimal imaging methods for craniosynostosis. The discussion of imaging findings are focused on ultrasonography, plain radiography, magnetic resonance imaging and computed tomography with 3-dimensional reconstruction. We suggest a strategy for imaging work-up for the diagnosis, treatment planning and follow-up to minimize or avoid ionized radiation exposure to children by reviewing the current literature.

Role of "major" and "minor" lambdoid arch sutures in posterior cranial fossa changes: mechanism of cerebellar tonsillar herniation in infants with multisutural craniosynostosis

PURPOSE

This study aimed to explain the functional role of lambdoid arch sutures in the development of cerebellar tonsillar herniation. Posterior cranial fossa (PCF) changes were investigated in infants with premature synostosis of the major and minor sutures of the lambdoid arch without premature synostosis of the PCF synchondroses.

METHODS

Morphometric and volumetric PCF measurements were performed on preoperative high-resolution CT studies in 12 infants with multisutural craniosynostosis involving the lambdoid arch and compared with those of 12 age-matched healthy subjects.

RESULTS

All 12 patients had hypoplasia of PCF bone structures and normal volumes of the PCF and neural structures. PCF hypoplasia was related to exocciput length in infants with isolated involvement of major sutures, while it was related to posterior skull base hemifossae in infants with isolated involvement of minor lambdoid arch sutures. Foramen magnum AP diameter was reduced in babies with major suture involvement and tonsillar herniation, while foramen magnum AP and LL diameters were reduced in babies with minor suture involvement without tonsillar herniation. Right and left jugular foramen (JF) areas differed in all infants; however, the area of the smaller JF was significantly reduced only in infants with involvement of minor lambdoid arch sutures.

CONCLUSION

Hypoplasia of PCF bone structures due to sutural synostosis of the lambdoid arch is a required predisposing but not sufficient factor for the development of cerebellar tonsillar herniation through the foramen magnum. Normal PCF volume and foramen magnum anatomy may partly explain the development of cerebellar tonsil herniation in infants with lambdoid arch synostosis.

Limiting CT radiation dose in children with craniosynostosis: phantom study using model-based iterative reconstruction

BACKGROUND

Medical professionals need to exercise particular caution when developing CT scanning protocols for children who require multiple CT studies, such as those with craniosynostosis.

OBJECTIVE

To evaluate the utility of ultra-low-dose CT protocols with model-based iterative reconstruction techniques for craniosynostosis imaging.

MATERIALS AND METHODS

We scanned two pediatric anthropomorphic phantoms with a 64-slice CT scanner using different low-dose protocols for craniosynostosis. We measured organ doses in the head region with metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters. Numerical simulations served to estimate organ and effective doses. We objectively and subjectively evaluated the quality of images produced by adaptive statistical iterative reconstruction (ASiR) 30%, ASiR 50% and Veo (all by GE Healthcare, Waukesha, WI). Image noise and contrast were determined for different tissues.

RESULTS

Mean organ dose with the newborn phantom was decreased up to 83% compared to the routine protocol when using ultra-low-dose scanning settings. Similarly, for the 5-year phantom the greatest radiation dose reduction was 88%. The numerical simulations supported the findings with MOSFET measurements. The image quality remained adequate with Veo reconstruction, even at the lowest dose level.

CONCLUSION

Craniosynostosis CT with model-based iterative reconstruction could be performed with a 20-μSv effective dose, corresponding to the radiation exposure of plain skull radiography, without compromising required image quality.