Sialidosis is a rare autosomal recessive hereditary disease caused by NEU1 gene mutations. A 25-year-old woman developed generalized tonic-clonic seizures since teenage, followed by progressive visional decline and limb myoclonus. Her sister had similar presentations. Both patients were products of a consanguineous marriage. Electroencephalography (EEG) revealed extensive paroxysmal spiky beta brush. Somatosensory evoked potentials (SEP) after stimulation of median nerves demonstrated giant SEP and C-reflex support the cortical origin of myoclonus. Genetic tests confirmed that both sisters carried the known pathogenic homozygous mutation of c.544A > G in exon 3 of the NEU1 gene. The diagnosis of sialidosis type 1 was then made. This suggests that neurophysiological abnormalities, especially spiky beta brush on EEG, might facilitate the early diagnosis of sialidosis type 1.
Keywords: NEU1 gene; Sialidosis type 1; electroencephalography.