EARLY VEP AND ERG EVIDENCE OF VISUAL DYSFUNCTION IN AUTOSOMAL RECESSIVE OSTEOPETROSIS

Autosomal recessive (AR) osteopetrosis has a rapid course and manifest s in the first months of life. Visual loss occurs because of optic ner ve compromise, and more rarefy retinal dysfunction (which may be a par t of a primary neurodegeneration). The only curative treatment current ly available is bone marrow transplantation (BMT). It has been suggest ed that BMT is contraindicated if AR osteopetrosis is associated with a primary neurodegeneration. Visual impairment tends to be irreversibl e after BMT. The young age of the patients makes reliable, objective t ests of visual function especially important. We have reviewed the fla sh electroretinograms (ERGs) and flash and pattern visual evoked poten tials (VEPs) recorded without sedation from 15 patients with AR osteop etrosis, 11 of whom were recorded longitudinally The most frequent, ea rly indication of visual dysfunction was a delay in the pattern or fla sh VEP latency. This first affects the pattern reversal VEP to small c hecks. importantly this often preceded fundal changes of optic disc pa llor, and evidence of optic nerve compression on neuroimaging. Only tw o patients had ERG evidence of retinal dysfunction affecting both rods and cones. One of these patients had a distinctive fundal appearance, but did not have evidence of associated neuronal degenerative disease . The other patient was lost to follow-up. In the patients reviewed in this study successful BMT and optic nerve decompression did not resul t in VEP improvement. Fundoscopy, VEP and ERG testing are indicated wh en the diagnosis of AR osteopetrosis is suspected and provide a useful means of monitoring visual involvement.