Neurofibromatosis 2 leads to choroidal hyperfluorescence in fluorescein angiography

Neurofibromatosis 2 leads to higher incidence of strabismological and neuro-ophthalmological disorders

PURPOSE

Ophthalmic features of neurofibromatosis 2 (NF2) include juvenile cataract, retinal hamartomas and tumours of the cranial nerves. We hypothesize that these tumours lead to strabismological and neuro-ophthalmological symptoms, including palsies of cranial nerves III, IV and VI, nystagmus and gaze palsies.

METHODS

We carried out a retrospective review of 73 patients with known genotype. They underwent ophthalmic, neuro-ophthalmological and strabismological examination. Statistical analysis was performed by calculating odds ratios and their 95% confidence intervals.

RESULTS

Mean best corrected visual acuity was 0.85. Strabismus was found in 38 of 73 patients (52%). A deviation based on a cranial nerve palsy was found in 16 patients (22%) and three had supranuclear palsies. Eleven of 73 patients had a nystagmus, mostly caused by peripheral-vestibular disturbance. Binocular single vision was normal in 41 (58%), subnormal in six (8%) and not present in 24 (34%) patients. The average refractive error was - 0.57 D. Myopia of >or= 0.5 D was present in 47 (33%) eyes and hyperopia of >or= 2.0 D was measured in 11 (8%) eyes. In the subgroup analysis of NF2 mutation types, the relative risk for cranial nerve palsies and negative stereopsis was statistically significantly increased for the nonsense mutation group. The mosaicism group had a statistically significant decreased relative risk for concomitant squint, as did patients with unfound mutations for strabismus and poor stereopsis.

CONCLUSIONS

The present study is, to our knowledge, the first to examine a larger collection of NF2 patients for strabismological and neuro-ophthalmological lesions. Compared with the normal population, our sample showed a higher amount of strabismus, refractive errors and an increased incidence of vestibular nystagmus.

Molecular studies of vestibular schwannomas: a review

PURPOSE OF REVIEW

To summarize advances in understanding the molecular biology of vestibular schwannomas over the past year.

RECENT FINDINGS

The role of the neurofibromatosis type 2 protein, denoted as merlin or schwannomin, in embryonic development, cellular adherence, and in cell proliferation has become better elucidated in the past year. Likewise, the role of merlin in Schwann cell-axon interaction has been studied. Additionally, two comprehensive analyses of the spectrum of human neurofibromatosis type 2 mutations have been compiled which make up a valuable resource in understanding critical regions of the neurofibromatosis type 2 gene. Neurofibromatosis type 2 screening guidelines for young patients with solitary vestibular schwannomas have been published. The role of electromagnetic radiation via cellular and portable telephones as a predisposing factor to vestibular schwannoma formation has also been the topic of several studies. Based on increased knowledge of the pathways in which merlin functions and the available transgenic and xenograft mouse models, preliminary data regarding directed pharmacotherapy are also summarized.

SUMMARY

With increased knowledge of the pathologic mechanisms and interacting proteins associated with merlin, the research community is poised to begin trials of targeted interventions in vitro and in the current mouse models.