Short mandible, maxilla and cranial base are common in patients with neurofibromatosis 1

Sphenoid Bone Pneumatisation on Lateral Cephalograms of Patients With Neurofibromatosis Type 1

BACKGROUND/AIM

Neurofibromatosis type 1 (NF1) is an autosomal dominant hereditary disease that causes tumors and many developmental disorders, e.g., cranial dysplasia. The purpose of this retrospective study was to analyse the pneumatisation of the sphenoid bone in NF1.

PATIENTS AND METHODS

The anonymised lateral cephalograms of 166 NF1 patients and 166 age- and sex-matched controls were examined for anterior-posterior sphenoid pneumatisation. The patient group analysis considered whether the patients had been affected by a facial plexiform neurofibroma (FPNF).

RESULTS

Sphenoid pneumatisation was significantly lower in NF1 patients than in controls [odds ratio (OR)=0.184; 95%CI=0.11-0.32; p<0.001]. A FPNF statistically significantly reduced sinus formation in patients (OR=0.38; p=0.002).

CONCLUSION

The condition 'NF1' has an effect on sphenoid pneumatisation. The findings are relevant for planning surgical procedures in this region and confirm current concepts to evaluate NF1 as a histogenesis control gene. The examination technique and basis of calculation presented here are easy-to-use and low-irradiation exposure instruments for screening for differences in sphenoid bone pneumatisation in defined populations.

Evaluation of the dimensions, morphology, and position of the mandibular condyles in individuals with neurofibromatosis 1: a case-control study

OBJECTIVES

The aim of this study was to evaluate the mandibular condyles of neurofibromatosis 1 (NF1) individuals without facial plexiform neurofibroma using cone beam computed tomography images.

MATERIALS AND METHODS

Eighty cone beam computed tomography scans (160 mandibular condyles) were analyzed: 40 from NF1 individuals (study group) and 40 from individuals without NF1 (control group). The anteroposterior and mediolateral dimensions, height, and volume of the mandibular condyles were measured. The mandibular condyles were classified according to their morphology: healthy (absence of morphological changes), with flattening (loss of rounded contour of at least one of the surfaces), with erosion (loss of continuity of the cortical bone), with osteophyte (exophytic formation of the condyle surface), and with sclerosis (any increase in the cortical thickness in the load-bearing areas). Furthermore, the position of the mandibular condyles in relation to the joint fossa in an anteroposterior view was classified as anterior, concentric, or posterior.

RESULTS

The study group had a higher anteroposterior dimension of the mandibular condyles compared with the control group (p < 0.05). There were no differences in condylar morphology and position between both groups (p > 0.05). The morphological alterations were not associated with sex or age in any group evaluated (p > 0.05). For both groups, the concentric position was the most common. For the study group, there was a significant difference in the condylar position between the sides (p < 0.05).

CONCLUSIONS

NF1 individuals without facial plexiform neurofibroma present a high prevalence of condyles with a large anteroposterior dimension and asymmetric position in the joint fossa. However, no morphological and volumetric changes were observed in the mandibular condyles of them.

CLINICAL RELEVANCE

The knowledge of the TMJ alterations in individuals with NF1 is important to establish an evaluation protocol, which would allow early intervention if indicated.

Non-Oncological Neuroradiological Manifestations in NF1 and Their Clinical Implications

Simple Summary

Central nervous system involvement (CNS) is a common finding in Neurofibromatosis type 1 (NF1). Beside tumor-related manifestations, NF1 is also characterized by a wide spectrum of CNS alterations with variable impacts on functioning and life quality. Here, we propose an overview of non-oncological neuroradiological findings in NF1, with an insight on pathophysiological and embryological clues for a better understanding of the development of these specific alterations.

Abstract

Neurofibromatosis type 1 (NF1), the most frequent phakomatosis and one of the most common inherited tumor predisposition syndromes, is characterized by several manifestations that pervasively involve central and peripheral nervous system structures. The disorder is due to mutations in the NF1 gene, which encodes for the ubiquitous tumor suppressor protein neurofibromin; neurofibromin is highly expressed in neural crest derived tissues, where it plays a crucial role in regulating cell proliferation, differentiation, and structural organization. This review article aims to provide an overview on NF1 non-neoplastic manifestations of neuroradiological interest, involving both the central nervous system and spine. We also briefly review the most recent MRI functional findings in NF1.

Sphenoid Wing Dysplasia in the Absence of Neurofibromatosis: Diagnosis and Management of a Novel Phenotype

Congenital sphenoid wing dysplasia is one of the major diagnostic criteria for neurofibromatosis type 1, and is often considered pathognomonic for the disease. Between 5% and 12% of neurofibromatosis type 1 cases have evidence of sphenoid wing dysplasia. Sequelae of this deficiency include slow expansion of the middle temporal fossa and progressive herniation of the temporal lobe into the orbital cavity, resulting in pulsatile exophthalmos. Herein, we report a patient with greater sphenoid wing agenesis and middle temporal fossa enlargement requiring transcranial orbital reconstruction in the absence of neurofibromatosis. To our knowledge, this represents a novel craniofacial phenotype of sphenoid wing agenesis in the absence of neurofibromatosis previously not described in the literature.

Craniofacial bone alterations in patients with neurofibromatosis type 1

Osseous manifestations of neurofibromatosis 1 (NF-1) occur in a minority of the affected subjects but may be because of significant clinical impairment. Typically, they involve the long bones, commonly the tibia and the fibula, the vertebrae, and the sphenoid wing. The pathogenesis of NF-1 focal osseous lesions and its possible relationships with other osseous NF-1 anomalies leading to short stature are still unknown, though it is likely that they depend on a common mechanism acting in a specific subgroup of NF-1 patients. Indeed, NF-1 gene product, neurofibromin, is expressed in all the cells that participate to bone growth: osteoblasts, osteoclasts, chondrocytes, fibroblasts, and vascular endothelial cells. Absent or low content of neurofibromin may be responsible for the osseous manifestations associated to NF-1. Among the focal NF-1 osseous anomalies, the agenesis of the sphenoid wing is of a particular interest to the neurosurgeon because of its progressive course that can be counteracted only by a surgical intervention. The sphenoid wing agenesis is regarded as a dysplasia, which is a primary bone pathology. However, its clinical progression is related to a variety of causes, commonly the development of an intraorbital plexiform neurofibroma or the extracranial protrusion of temporal lobe parenchyma and its coverings. Thus, the cranial bone defect resulting by the primary bone dysplasia is progressively accentuated by the orbit remodeling caused by the necessity of accommodating the mass effect exerted by the growing tumor or the progression of the herniated intracranial content. The aim of this paper is to review the neurosurgical and craniofacial surgical modalities to prevent the further progression of the disease by "reconstructing" the normal relationship of the orbit and the skull.

Intrauterine maxillary development and maxillary dental arch biometry: a fetal cadaver study

INTRODUCTION

This study's goal was to determine normal maxillary development on fetal cadavers.

MATERIALS AND METHODS

This study was carried out on 45 fetuses aged between the 17th - 40th weeks of gestation (24 male, 21 female). The distance between the widest left and right points of the maxillary dental arch (MDA) on the transverse plane, the distance of the papilla incisiva (PI) to the widest left and right points of the maxillary dental arch (MDAW), and the PI and posterior nasal spine (PNS) were measured. The average arch forms of the MDA were created according to trimester groups using the MATLAB program. The one-way ANOVA test was used to make a comparison between trimester groups, and ANOVA followed by post hoc analysis using the Bonferroni test was applied for comparisons. Pearson's correlation analysis was used for correlation analysis.

RESULTS

The data in the present study did not differ between genders. In the comparison between trimester groups, we did not find any difference between the 3rd trimester and full-term groups only in the PI-MDAW measurement. Other parameters increased with age. In the correlation analysis, the measurement values by age showed a strong positive correlation. The MDAW exhibited the best correlation with age (r_week = 0.919). When the average MDA forms created using the MATLAB program were evaluated, it was observed that the PI-MDAW of the average MDA in the 3rd trimester and full-term intersected.

CONCLUSIONS

This study provides a basis for a better understanding of fetal maxillary growth processes and can be useful to standardize the detection of malformations or intrauterine growth restrictions.

[Maxillofacial manifestations in children and adolescents with neurofibromatosis 1]

The aim of the study was to summarize literature data on oral and maxillofacial manifestations of neurofibromatosis I (NFI) and to analyze clinical case in with dentist had the leading role in proper diagnosis of the disease. Literature review showed main oral alterations in NFI to be: neurofibroma formation seen in 8-14% of children and adolescents, dysplastic «orthodontic» phenotype with shortened mandible, maxilla and sphenoid bones; radiologic signs including alveolar nerve canal and mental foramen widening in almost one third of patients; lesions of cranial nerves (mainly trigeminal, facial and glossopharyngeal), with non-specific paralysis clinic. These symptoms, however, develop gradually throughout the life and may be evident only in late adolescents. The most pathagnomic sigh is café-au-lait spots as they present in 95% of children at birth. The described clinical case demonstrates the difficulties in diagnostic of NFI in children in the absence of mutilating plexiform neurofibromas. The disease provoked significant functional disorders in maxillofacial area which resulted not only in lower quality of life but also mimicked iatrogenic complications of routine dental treatment.

Novel Three-Dimensional Morphometry to Reassess Orbit Deformities Associated With Orbital-Periorbital Plexiform Neurofibroma

BACKGROUND

Orbit deformities are usually found in neurofibromatosis type 1 patients, especially those with orbital-periorbital plexiform neurofibroma (OPPN). Unfortunately, current morphometry is complicated and, in some cases, cannot be performed on the deformed orbit due to the destruction of landmarks. Herein, we present a novel 3-dimensional (3D) morphometry for these orbital measurements.

METHODS

We retrospectively reviewed 29 patients with OPPN, and another 29 disseminated cutaneous neurofibroma patients served as controls. All patients had undergone craniofacial computed tomography and 3D reconstruction. New morphometry was used to measure the area of the orbital rim (OR) and superior orbital fissure (SOF).

RESULTS

For the 29 patients with OPPN, the area of the OR at the affected side was 14.18 ± 3.50 cm, while the OR at the nonaffected side was 12.32 ± 1.38 cm. In addition, the area of the SOF at the affected side was 5.37 ± 5.75 cm, while that at the nonaffected side was 1.27 ± 1.03 cm. The OR and SOF at the affected side are more likely to become enlarged compared with those at the nonaffected side. Among the 29 patients with OPPN, the novel morphometry could be performed in 19 cases (65.5%) that cannot be measured by previous morphometry.

CONCLUSION

The novel morphometry is convenient and reproducible, which optimizes its application in pathologic cases, especially those involving deformed orbits.

Craniofacial and oral alterations in patients with Neurofibromatosis 1

ABTSRACT

Neurofibromatosis type 1 (NF1) is one of the most common inherited syndromes. The literature on craniofacial alterations associated with NF1 has been limited and partially contradictory. This review is based on literature search and the results of the clinical study "Craniofacial and Oral Alterations and Speech in patients with Neurofibromatosis 1", carried out at the University of Turku and Turku University Hospital, Finland in 2006-2012. By the end of 2012, a total of 110 NF1 patients, 54 female and 56 male patients, were examined.A part of our results confirms pre-existing understanding, a part is contradictory to previous considerations based mainly on case reports, and some are entirely novel. Specifically, our results confirmed that enlargement the mandibular canal is the most common abnormality of the mandible in patients with NF1. It should be noted, however, that this finding does not require treatment. Caries was not a major problem. In fact, it was less frequent in NF1 patients compared to reference population. These findings abrogate some previous perceptions. Novel findings of our project include periapical cemental dysplasia in females; short jaws, a finding which usually does not affect bite; and immunohistological analysis of oral mucosal abnormalities. Pioneering study on speech showed that various deviations were very common: As many as 94% of the participants showed some alterations.To conclude, the awareness of craniofacial alterations common in NF1would help avoiding unnecessary and even harmful involvement, e.g. of periapical cemental dysplasia or enlarged mandibular canal which do not require treatment.

Decayed, missing, and restored teeth in patients with Neurofibromatosis Type 1

Background

NF1 is a relatively frequently occurring autosomal dominant inherited disease. There are conflicting reports about oral health status in NF1. The aim of this study was to analyze the dental status of patients with neurofibromatosis type 1 (NF1).

Material and Methods

Radiographs of 179 patients with NF1 were analyzed for decayed, missing, and filled teeth (DMFT) in a cross-sectional, retrospective study. The results were compared to age- and sex-matched controls of individuals not affected by NF1. The NF1 group was differentiated for facial tumor type and localization.

Results

Missing teeth were more frequently registered in the NF1 group. On the other hand, decayed teeth were more frequent in the reference group. However, these findings had to be interpreted with caution, because the type and localization of the facial tumor affected the measured values.

Conclusions

Dental health in terms of DMFT differed between NF1 patients and the control group. The presented results indicate the need for special care in dentistry in NF1 patients in order to preserve dental health, particularly in individuals affected with certain types of facial tumors.

Key words:DMFT index, neurofibromatosis type 1, plexiform neurofibroma, oral health.

Craniomaxillofacial morphology alterations in children, adolescents and adults with neurofibromatosis 1: A cone beam computed tomography analysis of a Brazilian sample

BACKGROUND

Oral manifestations are common in neurofibromatosis 1 (NF1), and include jaws and teeth alterations. Our aim was to investigate the craniomaxillofacial morphology of Brazilian children, adolescents and adults with NF1 using cone beam computed tomography.

MATERIAL AND METHODS

This study was conducted with 36 Brazilian individuals with NF1 with ages ranging from 4 to 75. The participants were submitted to anamnesis, extra and intraoral exam and cephalometric analysis using cone beam computed tomography. Height of the NF1 individuals was compared to the length of jaws and skull base. The results of the cephalometric measurements of the NF1 group were compared with a control group paired by age, gender and skin color.

RESULTS

Individuals with NF1 had lower maxillary length (p<0.0001), lower mandibular length (p<0.0001), lower skull base length (p<0.0001). In children and adolescents, the mandible was more posteriorly positioned (p=0.01), when compared with the control group. There was no association between jaws and skull base length with the height of the individuals with NF1.

CONCLUSIONS

Brazilian children, adolescents and adults with NF1 have short mandible, maxilla and skull base. Moreover, children and adolescents present mandibular retrusion.

Supernumerary Molars and Wisdom Tooth Shape Alterations in Patients with Neurofibromatosis Type 1

Objectives

The purpose of the present study was the systematic investigation of numerical and morphological aberrations of teeth in the wisdom teeth region in neurofibromatosis type 1 patients.

Material and Methods

The panoramic radiographs of 179 patients were analysed for supernumerary molars and dysplastic wisdom teeth with special reference to facial tumour type. The results were compared to radiographic findings obtained in panoramic radiographs of age- and sex-matched controls.

Results

The total number of dysplastic or supernumerary molars was 21 (17 individuals, 4.75%) and predominantly a finding of the maxilla (maxilla: 15, mandible: 1, maxilla and mandible: 1). Differences of dental findings between neurofibromatosis type 1 (NF1) patients (n = 15) and the control group (n = 2) were statistically significant (P < 0.01). All individuals with supernumerary molars were diagnosed as being affected with NF1. This difference achieved statistical significance when it was considered that the event may occur at least once per quadrant, and thus the individual potentially needs to be considered four times (P = 0.0038).

Conclusions

This investigation revealed that supernumerary molars and aberrations in wisdom tooth form are more common in patients than in age- and sex-matched controls. There is no association between these findings and a specific feature of the disease, id est facial manifestation of a trigeminal nerve sheath tumour (plexiform neurofibroma). The cause of this phenomenon is unknown. A review of these dental findings on other neurofibromatosis type 1 study groups should be attempted.

Update on 13 Syndromes Affecting Craniofacial and Dental Structures

Care of individuals with syndromes affecting craniofacial and dental structures are mostly treated by an interdisciplinary team from early childhood on. In addition to medical and dental specialists that have a vivid interest in these syndromes and for whom these syndromes are of evident interest, experts of scientific background-like molecular and developmental geneticists, but also computational biologists and bioinformaticians-, become more frequently involved in the refined diagnostic and etiological processes of these patients. Early diagnosis is often crucial for the effective treatment of functional and developmental aspects. However, not all syndromes can be clinically identified early, especially in cases of absence of known family history. Moreover, the treatment of these patients is often complicated because of insufficient medical knowledge, and because of the dental and craniofacial developmental variations. The role of the team is crucial for the prevention, proper function, and craniofacial development which is often combined with orthognathic surgery. Although the existing literature does not provide considerable insight into this topic, this descriptive review aims to provide tools for the interdisciplinary team by giving an update on the genetics and general features, and the oral and craniofacial manifestations for early diagnosis. Clinical phenotyping together with genetic data and pathway information will ultimately pave the way for preventive strategies and therapeutic options in the future. This will improve the prognosis for better functional and aesthetic outcome for these patients and lead to a better quality of life, not only for the patients themselves but also for their families. The aim of this review is to promote interdisciplinary interaction and mutual understanding among all specialists involved in the diagnosis and therapeutic guidance of patients with these syndromal conditions in order to provide optimal personalized care in an integrated approach.

A lateral cephalometry study of patients with neurofibromatosis type 1

PURPOSE

Neurofibromatosis type 1 (NF1) is an autosomal dominant transmitted tumour suppressor syndrome and also a bone disease. Osseous dysplasia affecting the craniofacial region is characteristic of NF1. The aim of this study was to analyse the lateral cephalograms of NF1 patients in comparison to individuals who were not affected by this condition in order to describe the skeletal phenotype of NF1 in more detail.

MATERIALS AND METHODS

The study comprises the lateral cephalograms of 172 patients with established NF1 diagnoses (female = 85, male = 87). NF1 patients were distinguished by radiological and/or histological findings of the facial region suggestive of plexiform neurofibroma (PNF) or disseminated cutaneous NF (DNF). The analysed radiographs of a collection of 29 healthy volunteers with ideal occlusion served as controls. The focus of this analysis was cephalometrically defined angles.

RESULTS

Cephalometric analyses of patients with DNF did not differ from those of controls for the vast majority of parameters. However, the measurement results of patients with PNF differed significantly from those of healthy volunteers and patients with DNF. The number of trigeminal nerve branches affected in PNF patients had an effect on the measurement results.

CONCLUSION

Lateral cephalograms revealed no significant alteration of the facial skeleton in NF1 patients as compared to controls. Indeed, the stigma of a so-called 'NF1 facies' cannot be derived from the cephalometric findings presented. Notably, a wide range of deviating readings were recorded for individuals with facial PNF. Clinicians who treat patients with NF1 should be aware of deviations from cephalometric standards on lateral cephalograms in NF1 patients, especially when craniofacial surgical procedures are planned. Some of these findings, particularly asymmetries of the facial skeleton, could be indicators of an associated PNF.

Fetal and neonatal maxillary ontogeny in extant humans and the utility of prenatal maxillary morphology in predicting ancestral affiliation

OBJECTIVES

The midface of extant Homo sapiens is known to undergo shape changes through fetal and neo-natal ontogeny; however, little work has been done to quantify these shape changes. Further, while midfacial traits which vary in frequency between populations of extant humans are presumed to develop prenatally, patterns of population-specific variation maxillary shape across ontogeny are not well documented. Only one study of fetal ontogeny which included specific discussion of the midface has taken a three-dimensional geometric morphometric approach, and that study was limited to one population (Japanese). The present research project seeks to augment our understanding of fetal maxillary growth patterns, most especially in terms of intraspecific variation.

MATERIALS AND METHODS

Three-dimensional coordinate landmark data were collected on the right maxillae of 102 fetal and neo-natal individuals from three groups (Euro-American, African-American, "Mixed Ancestry").

RESULTS

Shape changes were seen mainly in the lateral wall of the piriform aperture, the anterior nasal spine, and the subnasal alveolar region. The greatest difference across age groups (second trimester, third trimester, neonates) was between the second and third trimester. Euro-Americans and African-Americans clustered by population and differences in midfacial morphology related to ancestry could be discerned as early as the second trimester (p = .002), indicating that population variation in maxillary morphology appears very early in ontogeny.

DISCUSSION

The midface is a critical region of the skull for assessing ancestry and these results indicate that maxillary morphology may be useful for estimating ancestry for prenatal individuals as young as the second trimester.

Cephalometry in adults and children with neurofibromatosis type 1: Implications for the pathogenesis of sphenoid wing dysplasia and the "NF1 facies"

BACKGROUND

Neurofibromatosis type 1 (NF1) is a common, autosomal dominant tumor-predisposition disorder that arises secondary to mutations in the tumor suppressor gene NF1. Cephalometry is an inexpensive, readily available and non-invasive technique that is under-utilized in studying the NF1 craniofacial phenotype. An analysis of NF1 cephalometry was first published by Heervä et al. in 2011. We expand here on that first investigation with a larger cohort of adult and pediatric patients affected with NF1 and sought objective insight into the NF1 facies, said to feature hypertelorism and a broad nasal base, from cephalometric analysis.

METHODS

We obtained cephalograms from 101 patients with NF1 (78 adults and 23 children) from two NF1 protocols at the National Institutes of Health. Each subject had an age-, gender- and ethnicity-matched control. We used Dolphin software to make the cephalometric measurements. We assessed the normality of differences between paired samples using the Shapiro-Wilk test and evaluated the significance of mean differences using paired t-tests and adjusted for multiple testing. We explored the relationship between the cephalometric measurements and height, head circumference and interpupillary distance.

RESULTS

In this dataset of American whites with NF1, we confirmed in a modestly larger sample many of the findings found by Heerva et al. in an NF1 Finnish cohort. We found a shorter maxilla, mandible, cranial base, (especially anteriorly, p = 0.0001) and diminished facial height in adults, but not children, with NF1. Only one adult exhibited hypertelorism.

CONCLUSIONS

The cephalometric differences in adults arise in part from cranial base shortening and thus result in a shorter face, mid-face hypoplasia, reduced facial projection, smaller jaw, and increased braincase globularity. In addition, we suggest that NF1 sphenoid bone shortening, a common event, is consistent with an intrinsic NF1 bone cell defect, which renders the bone more vulnerable to a random "second hit" in NF1, leading to sphenoid wing dysplasia, a rare event.

Maxillary dental arch biometry: assessment with fetal MR imaging

OBJECTIVE

To define normal growth of the fetal maxillary dental arch using magnetic resonance imaging.

METHOD

Four hundred twenty-four consecutive fetuses (18 to 37 weeks) with a morphologically normal anatomy or only minor malformations, not affecting bone growth and face anatomy were included. On axial T2-weighted images the dental arch length and width were measured. The measurements were correlated with gestational age and the biparietal diameter (BPD) of the fetal head using correlation and regression analysis.

RESULTS

A linear growth relationship was observed between the dental arch length and gestational age (r = 0.86; p = < 0.0001; y = -1.85 + 0.75 × gestational age) and the dental arch width and gestational age (r = 0.92; p = < 0.0001; y = -2.19 + 1.05 × gestational age). A significant correlation was found between the dental arch length and the BPD (r = 0.903; p = < 0.0001) and the dental arch width and the BPD (r = 0.927; p = < 0.0001). The interobserver variability showed good agreement for the dental arch length (intraclass coefficient 0.981; r = 0.963) and width (intraclass coefficient 0.987; r = 0.974), respectively.

CONCLUSION

We present a nomogram for the in utero assessment of the fetal dental arch. These data may help in the early detection of abnormal dental arch development.