Browsing by Subject "HYPSARRHYTHMIA"

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  • Nevalainen, Päivi; Metsäranta, Marjo; Toiviainen-Salo, Sanna; Marchi, Viviana; Mikkonen, Kirsi; Vanhatalo, Sampsa; Lauronen, Leena (2020)
    Purpose: To evaluate the accuracy of hypoxic ischemic encephalopathy (HIE) grade, and neonatal neurophysiological and neuroimaging measures for predicting development of infantile spasms syndrome (IS) or other postneonatal, infantile onset epilepsy after perinatal HIE. Methods: We examined a population-based cohort of 92 consequent infants with moderate-to-severe HIE. The HIE grade and neonatal neuroimaging (MRI) and neurophysiology (EEG and somatosensory evoked potentials, SEPs) findings were compared to the development of IS or other epilepsy within the first year of life. Results: Out of 74 surviving infants with follow-up information, five developed IS and one developed a focal onset epilepsy. They all had recovered from severe HIE. All survivors with inactive neonatal EEG (recorded within the first few postnatal days, n = 4) or the most severe type of brain injury in MRI (n = 3) developed epilepsy (positive predictive value, PPV 100 %). Bilaterally absent SEPs had 100 % sensitivity and 75 % PPV for epilepsy. A combination of absent SEPs and a poor MRI finding (combined deep and cortical gray matter injury) resulted in higher PPV (86 %) without lowering sensitivity (100 %). Follow-up EEGs showed recurrent epileptiform activity already between 1- and 2-months age in those that developed epilepsy, distinguishing them from those surviving without epilepsy. Conclusions: Poor neonatal neuroimaging and neurophysiological findings provide accurate prediction for development of infantile onset epilepsy after HIE. Of the neonates with severe HIE, the ones with severe neonatal MRI and neurophysiological abnormalities need frequent follow-up, including repeated EEGs, for early detection of IS.
  • Anttonen, Anna-Kaisa; Laari, Anni; Kousi, Maria; Yang, Yawei J.; Jääskeläinen, Tiina; Somer, Mirja; Siintola, Eija; Jakkula, Eveliina; Muona, Mikko; Tegelberg, Saara; Lönnqvist, Tuula; Pihko, Helena; Valanne, Leena; Paetau, Anders; Lun, Melody P.; Hästbacka, Johanna; Kopra, Outi; Joensuu, Tarja; Katsanis, Nicholas; Lehtinen, Maria K.; Palvimo, Jorma J.; Lehesjoki, Anna-Elina (2017)
    Progressive encephalopathy with oedema, hypsarrhythmia, and optic atrophy (PEHO) syndrome is an early childhood onset, severe autosomal recessive encephalopathy characterized by extreme cerebellar atrophy due to almost total granule neuron loss. By combining homozygosity mapping in Finnish families with Sanger sequencing of positional candidate genes and with exome sequencing a homozygous missense substitution of leucine for serine at codon 31 in ZNHIT3 was identified as the primary cause of PEHO syndrome. ZNHIT3 encodes a nuclear zinc finger protein previously implicated in transcriptional regulation and in small nucleolar ribonucleoprotein particle assembly and thus possibly to pre-ribosomal RNA processing. The identified mutation affects a highly conserved amino acid residue in the zinc finger domain of ZNHIT3. Both knockdown and genome editing of znhit3 in zebrafish embryos recapitulate the patients' cerebellar defects, microcephaly and oedema. These phenotypes are rescued by wild-type, but not mutant human ZNHIT3 mRNA, suggesting that the patient missense substitution causes disease through a loss-of-function mechanism. Transfection of cell lines with ZNHIT3 expression vectors showed that the PEHO syndrome mutant protein is unstable. Immunohistochemical analysis of mouse cerebellar tissue demonstrated ZNHIT3 to be expressed in proliferating granule cell precursors, in proliferating and post-mitotic granule cells, and in Purkinje cells. Knockdown of Znhit3 in cultured mouse granule neurons and ex vivo cerebellar slices indicate that ZNHIT3 is indispensable for granule neuron survival and migration, consistent with the zebrafish findings and patient neuropathology. These results suggest that loss-of-function of a nuclear regulator protein underlies PEHO syndrome and imply that establishment of its spatiotemporal interaction targets will be the basis for developing therapeutic approaches and for improved understanding of cerebellar development.