Abstract
Abstract: :
Purpose: LHON is a maternally inherited mithocondrial disease characterized by bilateral, usually sequential, rapid loss of central vision which prevalently affects young males. The purpose of this study was to investigate electrophysiologically a small cohort of members from an extensive Brazilian family affected by LHON. Methods: Pattern-reversal visual evoked potentials (PVEP), and full-field electroretinogram (ERG) were performed on 4 members from a newly discovered extensive Brazilian family with the 11778 mtDNA point mutation LHON: a 14 years-old recently affected, his unaffected mother and her two affected brothers. In these three affected members, visual acuity ranged from 20/250 to HM, visual fields showed a variable caeco-central defect and severe dyschromatopsia was detected by FM-100 test. The unaffected female had normal findings for visual acuity, visual fields and color discrimination. Results: Severely prolonged P100 latencies (peak times 130-137 ms) and decreased N75-P100 peak amplitudes were found in pattern-reversal VEPs for 2 affected members, with the remaining showing non-detectable responses. Normal VEP responses were found in the carrier female. Both rod and cone ERG responses were normal in 2 affected members. However, the mother and son showed reduced peak-to-peak amplitude for both single-flash cone response and 30 Hz flicker with normal b-wave implicit times. Conclusion: Optic nerve function, evaluated by PVEP, was severely reduced in LHON affected members and normal in the carrier female. However, reduced ERG cone responses suggest that LHON can also affect retinal elements, even preceding fundus changes. Follow-up studies will help to better understand functional outcomes in these patients.
Keywords: 393 electrophysiology: clinical • 486 neuro-ophthalmology: diagnosis • 395 electroretinography: clinical