[Neurofibromatosis type 1: more frequent and severe then usually thought]

To study prevalence of clinical features among Brazilian patients diagnosed with neurofibromatosis type 1(NF1), comparing these features with international data to evaluate the severity and visibility of the disease and quantify less frequent manifestations such as short stature, macrocephaly, muscle strength, voice abnormalities and oral motor disorders.

183 patients diagnosed with NF1, attended at the Neurofibromatosis Outpatient Reference Center, were evaluated for clinical manifestations and complications of NF1. Severity and visibility were verified using the Riccardi and Ablon scales respectively. Voice abnormalities and oral motor disorders were quantified using the Vox-Metria software and maximal voluntary muscle strength (MVMS) was quantified using a handgrip dynamometer.

Clinical manifestations of NF1 observed were comparable to those described in literature. However, more then 50% of patients presented severity and visibility classified as moderate and severe. The incidence of macrocephaly and short stature was higher among the Brazilian patients. Voice abnormalities and oral motor disorders were quantified for the first time, with hoarseness and oral motor disorders observed in more then 60% the patients. Maximal voluntary muscle strength was found to be reduced in 67% of patients.

The main clinical features of these patients are similar to those reported in previous studies. More then one-half of the patients presented moderate and severe levels of NF1 (severity and visibility), including short stature, macrocephaly, voice abnormalities and oral motor disorders and decreased muscle strength. These results are in disagreement with the traditional concept that NF1 is a benign disease and also disclosed some clinical aspects not previously reported.