Posterior-Anterior Cephalometric Study of Neurofibromatosis Type 1 Patients With Facial Plexiform Neurofibroma: Analysis of Skeletal Symmetry Concerning Midfacial and Skull Base Reference Points (Zygomatic Arch, Mastoid, and Juga).

Abstract

Neurofibromatosis type 1 (NF1) is an autosomal dominant tumor predisposition syndrome that is also characterized by skeletal abnormalities. In the cranial region, skeletal dysplasia is observed that is associated with a characteristic peripheral nerve sheath tumor, the plexiform neurofibroma (PNF). The aim of the study was to determine PNF-associated skeletal asymmetries of the mid-skull and skull base as an indicator of local tumor development. The distances of the zygomatic arch, mastoid, and juga measurement points from the interorbital horizontal plane and median sagittal plane were examined on anterior-posterior cephalograms of 168 NF1 patients (females: 82, males: 86) and compared with the findings of a control group. A distinction was made as to whether the patients had developed a facial PNF. The distances of the measurement points from the reference planes differed between the patient and control group (p<0.05). Within the NF1 patients, differences between certain distances were noted when comparing patients with PNF and without PNF (p<0.05). In PNF patients, discrete changes in the skull contour were also detectable on the non-affected side (p<0.05). The caudal measurement point of the skull base showed no changes in the group comparison. The individually very variable facial PNF in NF1 is associated with deformations and misalignments of midfacial bones that follow a pattern quantifiable with cephalometric analysis.