A lateral cephalometry study of patients with neurofibromatosis type 1

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.

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.

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.

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.