Syndromic retinitis pigmentosa: ERG and phenotypic changes

Purpose: Our aim was to review the phenotype and extent of ERG changes in syndromic RP (SRP). Patients and methods: A retrospective review of charts of 82 patients seen over the last 20 years with SRP was carried out. Clinical data were compared with changes in ERG. Full-field ERGs comprised selective rod-driven, maximal dark-adapted mixed responses, and isolated cone-driven signals. Occasionally, ERGS were recorded under brief general anaesthesia. ERG changes were classified as normal, reduced or extinguished. Results: Syndromic RP was diagnosed for the following entities: Usher (45 patients), Laurence-Moon-Bardet-Biedl (LMBB, 17 patients), Kearns-Sayre (10), Batten (6), Refsum (3), Senior-Loken (1). ERG changes varied in every subgroup and were therefore not specific for the syndromes. Conclusion: There was wide variation of clinical presentation in SRP, much as seen in isolated RP, often without obvious ophthalmoscopic changes. ERG testing is a prerequisite for differential diagnosis as well as for early detection of multiple handicaps.