Characterization of early onset neurofibromatosis type 2.

Neurofibromatosis type 2 (NF2) is an autosomal dominant multiple neoplasia syndrome of the central nervous system. The aim of the present study was to characterize the clinical course of early onset NF2. The specific Japanese disease registry for NF2 in 2010 was analyzed retrospectively. The male:female ratio for the 312 patients identified in the database was 1:1.29. The median age at onset was 25years (range 2-76years), with 31.3% of patients exhibiting symptoms at <20years of age. Patients with an age at onset of <20years were found to have more frequent spinal cord and extravestibular cranial nerve involvement, cutaneous signs, and convulsions than patients with a later age at onset. Of patients younger than 18years of age, half did not exhibit hearing problems; in contrast, they frequently had other cranial nerve schwannomas, cranial meningioma, spinal cord tumors, and subcutaneous schwannoma. There were weak but significant positive correlations between symptomatic periods and disability scores in patients with an age of onset of ⩾20years (R=0.225; P<0.01) and those with an earlier age of onset (R=0.306; P<0.01). Although there were no significant differences in disability scores between genders or patients with an age at onset of <20 versus ⩾20years, patients with an earlier age at onset had significantly higher disability scores for spinal symptoms than patients with an age at onset of ⩾20years. Atypical extravestibular presentation is common in early onset NF2, with more prominent spinal symptoms.