A Posterior-Anterior Cephalometric Study of Skull Symmetry in Patients With Neurofibromatosis Type 1.

BACKGROUND/AIM: Neurofibromatosis type 1 (NF1) is a tumor predisposition syndrome. Bone findings make a significant contribution to the clinical diagnosis of NF1. It has been suggested that there are characteristic skeletal features of the NF1 patients' skull that cause a specific 'NF1 facies'. To test this thesis, skull examinations were carried out on NF1 patients. PATIENTS AND METHODS: The posteroanterior (PA) cephalograms of 76 patients with NF1 were analyzed using defined measuring points. Patients with confirmed facial plexiform neurofibromas (PNF) were excluded from the study. A special interest of the investigation was the symmetry of the measuring points defined as the distance to the median sagittal plane. RESULTS: NF1 patients have a slightly larger distance to the Z-plane than controls at the zygomatic arch and mastoid measurement points (p=0.027 and 0.028, respectively). In contrast, the distances of the juga and antegonion measurement points from the horizontal reference plane are larger in the control group (p=0.002 and 0.480, respectively). The transverse development of the midface at the level of the zygomatic arch showed no differences from the control group (p=0.841). The transverse diameter of the skull at the mastoid and juga measurement points is smaller in the NF1 group compared to the control group (p=0.010 and 0.002, respectively). There is a statistically significant left-right (LR) asymmetry of the distances to the median sagittal plane in favor of the left side in the patient group (p=0.002 to 0.037). However, the numerical deviations from the control group are small overall. CONCLUSION: Considering the natural, biological deviations of cephalometric measurements of the individual from idealized geometric norms, the facial skeleton of NF1 patients is symmetrically developed. It is unlikely that the calculated LR asymmetry of the patients has a visible effect. In comparison to cephalometric values of a normal population, no characteristic facial skeleton of the NF1 patient in the PA projection of the skull can be derived from these findings. Clear asymmetries of the facial skeleton should give rise to further diagnosis to clarify the suspicion of facial PNF.

Relationships of Reference Points, Planes and Skull Symmetry on Posterior-anterior Cephalograms in Healthy Young Adults.

BACKGROUND: Radiological cephalometry is an important diagnostic tool for analyzing the shape and proportions of the skull. Standardized teleradiography of the skull in posterior-anterior (PA) projection provides orientation data on the symmetry and vertical relations of the skull. The comparison of individual findings with normal values places high demands on the selection of a control group. The aim of this study was to characterize a group to be used as a standard for cephalometric comparisons. PATIENTS AND METHODS: PA teleradiographs of 23 healthy young adults were analyzed. Distances from reference measuring points to the median sagittal plane and the orbital horizontal plane were made. All individuals showed ideal occlusion. None of the participants had been subjected to orthodontic therapy or craniomaxillofacial surgery. RESULTS: The measurement results showed a high degree of lateral symmetry of the skeletal reference points and planes. Comparison of the vertical reference lines confirmed the symmetrical constitution of the facial skeleton. CONCLUSION: The study group is suitable for comparison with the cephalometric evaluations of other study groups.

Microdont Developing Outside the Alveolar Process and Within Oral Diffuse and Plexiform Neurofibroma in Neurofibromatosis Type 1.

BACKGROUND/AIM: Numerical aberrations of permanent dentition and dystopic tooth eruption are part of the phenotype of the tumor predisposition syndrome neurofibromatosis type 1 (NF1). In these cases, surplus tooth germs usually develop in the alveolar processes of the jaw. This report attests to the dystopic development of a dysplastic supernumerary tooth in NF1 arising outside the jaw. CASE REPORT: The 8-year-old male patient developed a microdont outside the bone and above the occlusal plane of the retained maxillary right second molar. The supernumerary tooth was completely embedded in oral soft tissue. Hyperplastic oral soft tissue in the molar region and microdont were excised. Specimen of the mucosa surrounding the teeth was interspersed with diffuse and plexiform neurofibroma. The retained upper right first molar emerged spontaneously within a few months after surgery. The upper right second molar did not change position. CONCLUSION: Odontogenesis can take place within tumorous oral mucosa in NF1. Surgical removal of the tumorous mucous membrane facilitates tooth eruption in some cases.

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.

Supernumerary teeth of permanent dentition in patients with neurofibromatosis type 1.

PURPOSE: The purpose of the study was the investigation of supernumerary teeth (ST) in the permanent dentition of patients with neurofibromatosis type 1 (NF1). MATERIAL AND METHODS: The panoramic radiographs of 200 NF1 patients were analysed for ST. The potential impact of certain neurogenic facial tumours on the measured variable was investigated separately. The results were compared to dental findings in panoramic radiographs of 200 age- and sex-matched controls. RESULTS: The total number of ST in all individuals was 23 in 12 patients (3% of total population). However, all ST had developed in the group of NF1 patients (6%), (p = 0.0004). ST were particularly common distal to the molar region. Although ST occur in the region of facial plexiform neurofibroma, the numerical aberrations of the dentition are independent of specific type of facial nerve sheath tumour. CONCLUSION: The unusual accumulation of ST in the terminal sections of molar development could be an indicator of preferred points of developmental disorder, in which the genetic predisposition of the patient is involved. Reviewing the results of other NF1 patient collectives is desirable.

Non-odontogenic Intraosseous Radiolucent Lesions of the Mandibular Body Are Rare Findings on Panoramic Views of Patients With Neurofibromatosis Type 1.

BACKGROUND/AIM: The purpose of the study was to investigate whether non-odontogenic intraosseous translucent lesions of mandibular body are depicted on radiographs of patients with neurofibromatosis type 1 (NF1). MATERIALS AND METHODS: The panoramic radiographs of 179 NF1 patients were analysed for translucent lesions of the mandibular body that were of intraosseous, non-odontogenic origin. The results were compared to findings obtained in panoramic radiographs of age- and sex-matched controls. RESULTS: Only three patients showed intraosseous translucent lesions. These were always unilocular findings. There were no statistically significant differences between the groups (p=0.248). CONCLUSION: Intraosseous neurofibroma of the jaw is a very rare finding in NF1 patients compared to oral neurofibromas. Accurate and exact diagnosis should be made in the case of such findings because malignant tumours in the jaw area can arise in rare cases in NF1 patients. Plain radiology findings cannot clearly indicate the type and biology of the lesion.

Sella turcica measurements on lateral cephalograms of patients with neurofibromatosis type 1.

The aim of this study was to measure line segments and areas of sella turcica on lateral cephalograms with respect to the clinical diagnosis of facial phenotype of patients with neurofibromatosis type 1 (NF1). Special attention was given to correlate the measured values with certain tumour types that are typical for this disease. Material and methods: Lateral cephalograms of 194 individuals were investigated. Patients with NF1 were further divided according to the detection and topography of facial plexiform neurofibromas (PNF) taking into account the distribution pattern of the trigeminal nerve. All patients with PNF showed unilateral tumour localisation. Patients without any facial PNF constituted a separate group. Healthy volunteers with ideal occlusion and no history of any intervention in the maxillofacial region served as a control group. The following items were determined on the radiographs: sella entrance, sella width, sella depths, sella diagonal, and sella area. Results: Patients with PNF of the first and second trigeminal nerve branch or affected in all branches showed highly statistically significant enlarged sella tucica measurement values. On the other hand, patients with PNF restricted to one branch only or simultaneously in the second and third branches showed measurement values that were not different to those obtained in NF1 patients devoid of facial PNF. The latter group also showed no difference of sella turcica parameters obtained in the control group. Conclusion: This study provides evidence for the association of a certain NF1 phenotype with distinct skeletal alterations of the skull base, shown here using the example of the representation of the sella turcica in the lateral radiograph. These findings are also relevant in the discussion of NF1 as a disease of bones and in the assessment of brain development in NF1. Both items are discussed in relationship to a facial plexiform neurofibroma. Furthermore, the knowledge of this association of findings provides the clinician with relevant information in the planning of skull base procedures in these patients.

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.