The skull base in NF1 phenotypes on lateral cephalograms.

Neurofibromatosis type 1 (NF1) influences skeletal growth processes. We investigated the effect of the disease and associated neurogenic craniofacial tumors on the skull base. We examined skull base parameters on lateral cephalograms in patients with (N = 74) facial plexiform neurofibroma (FPNF) and 92 without and the same number of age- and sex-matched controls. The measurements were analyzed for mean differences and certain parameters (sex, age (< or ≥ 18 years), tumor type). The application of the skull base angle as a diagnostic parameter was explored. We found statistically significant elongation of the anterior and a shortening of the posterior skull base, as well as an increase of the skull base angle in NF1 patients compared with controls. The effect sizes of comparisons varied in strength. The effect of tumor type in NF1 patients on the parameter was revealed in adults. NF1 and especially FPNF affect the development of the skull base. The changes in the posterior skull base may indicate the beginning of a continuum of posterior skull base dysplasia, as has been repeatedly described in NF1. However, differences in the measurements were small. The skull base relationships do not provide a skeletal basis defining a proposed pathognomonic NF1 facies.