Neurofibromatosis Type 1: Ocular Electrophysiological and Perimetric Anomalies

Abstract

Introduction

Neurofibromatosis type 1 (NF1) is a multisystemic disease caused by the mutation of Nf1 gene located on chromosome 17q11.2. The mutation determines the loss of function of the protein neurofibromin with consequent uncontrolled cellular proliferation. Patients are characterized by a wide range of dermatological, neurological, and ophthalmological symptoms.

Purpose

The aim of the study was to evaluate, through pattern visual evoked potentials (p-VEPs) and frequency doubling technology (FDT) Matrix perimetry, the objective and psychophysical functionality of the optic pathways in a group of NF1 patient.

Methods

The study group consisted of 26 patients affected by NF1 and 17 healthy controls. Each patient underwent a complete ophthalmological examination, p-VEPs with the evaluation of amplitude and latency of the P100 wave, and FDT perimetry, with the evaluation of central sensitivity (CS), mean deviation (MD), pattern standard deviation (PSD) and glaucoma hemifield test (GHT).

Results

NF1 patients showed a statistically significant alteration in the transmission of visual impulse. P-VEPs results highlighted a reduced amplitude and an increased latency of the P100 wave, suggesting an involvement of the visual pathway. Visual field analysis showed a significant reduction in all the observed parameters as well (CS, MD, PSD, and GHT).

Conclusion

The present study showed, in NF1 patients, a qualitative and quantitative alteration in the conduction of stimuli through the visual pathways. The observed alterations are present, although, only at a subclinical level. None of the patients included in the study showed any manifest visual deficit nor had any concomitant pathology that might have affected the outcome of the study. In conclusion, electrophysiological exams and computer perimetry may take part, alongside a wider array of exams, in the differential diagnosis and later monitoring of NF1.

Keywords:

• electrophysiologic testing
• frequency doubling technology Matrix perimetry
• FDT
• neurofibromatosis type 1
• optic glioma
• pattern visual evoked potentials

Abbreviations

p-VEPs, pattern visual evoked potentials; FDT, frequency doubling technology; CS, central sensitivity; MD, mean deviation; PSD, pattern standard deviation; GHT, glaucoma hemifield test; NF1, Neurofibromatosis type 1.

Ethical Approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.

Informed Consent

Informed consent was obtained from all individual participants included in the study.

Disclosure

All authors certify that they have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus, membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent licensing arrangements), or non-financial interest (such as personal or professional relationships, affiliations, knowledge or beliefs) in the subject matter or materials discussed in this manuscript.

Additional information

Funding

No funding was received for this research.