Abstract
Purpose: :
Pantothenate Kinase-Associated Neurodegeneration (PKAN) is a rare autosomal recessive degenerate extrapyramidal motor disorder with a spectrum of neurologic abnormalities and progressive dementia. Few published studies have reported pigmentary retinopathy, optic atrophy, neuro-ophthalmic motility disorders and electroretinographic (ERG) abnormalities. No study to date has examined electro-oculographic (EOG) and visual evoked potential (VEP) deficiencies correlating to pigmentary retinopathy and optic atrophy with genetically confirmed mutations in the PANK2 gene.
Methods: :
Retrospective observational case report
Results: :
A 9 year old boy with severe motor and verbal dyspraxia, dysarthria and motor planning difficulties presented with nyctalopia and recurrent falls. Dilated fundoscopy revealed mild bilateral optic disc temporal pallor with attenuated retinal vessels and subtle pigmentary retinopathy. EOG demonstrated markedly reduced light rise amplitude (R-478um; L-500.5um) with reduced Arden ratio (R-1.37; L-1.31; 98%CI). ERG showed abnormal scotopic responses with rod ERG, maximal rod-cone ERG and oscillatory potentials were essentially flat. Photopic responses showed reduced amplitudes and prolonged latencies for both a- and b-waves. Flicker ERGs and pattern ERGs were also abnormal. In small check VEP, the principal component is delayed (latency 120ms) and broadened (width 88-90ms; 98%CI). T2 MRI imaging revealed a characteristic ‘eye of tiger’ sign. Two mutations in the PANK2 gene were identified; 1112-1114delGAG mutation in exon 5 and 1352_A(G451E) mutation in exon 7.
Keywords: genetics • electrophysiology: clinical • optic nerve