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  • Updated 05.19.2023
  • Released 04.19.2000
  • Expires For CME 05.19.2026




Progressive encephalopathy with edema, hypsarrhythmia, and optic atrophy (PEHO) syndrome was first described in Finland, but several patients have been reported from other European and non-European countries. The main features of this autosomal recessive disorder are infantile spasms, severe hypotonia with absence of developmental milestones, blindness, subcutaneous edema of hands and feet, and characteristic dysmorphic features. Data suggest the presence of one major locus in Finnish families with this disorder. In this article, the author describes the main clinical diagnostic findings, emphasizing early progressive brain atrophy, which starts in the cerebellum and brainstem.

Key points

• PEHO is a neurodegenerative disorder with early infantile onset.

• PEHO and PEHO-like syndrome are clinically and genetically diverse entities.

• PEHO and PEHO-like syndrome may be phenotypic endpoints of many severe genetic encephalopathies.

• The inheritance of PEHO in familial cases is autosomal recessive, although most PEHO-spectrum patients represent sporadic cases.

• PEHO was named according to the main clinical findings: progressive encephalopathy with edema, hypsarrhythmia, and optic atrophy.

• Severe hypotonia, blindness, and edema of the face and limbs are typical signs.

• Early brain atrophy, starting in the cerebellum, is the most distinguishing diagnostic feature.

Historical note and terminology

Progressive encephalopathy with edema, hypsarrhythmia, and optic atrophy (PEHO) is a progressive infantile brain disorder, first identified by Salonen and colleagues in 14 patients from 11 Finnish families (37). The combination of profound mental retardation with epilepsy, absence of developmental milestones, severe hypotonia with hyperreflexia, transient or persistent subcutaneous edema, and blindness, together with characteristic dysmorphic features, allowed recognition of these patients. It was named according to the main clinical findings (Progressive encephalopathy with Edema, Hypsarrhythmia, and Optic atrophy), and diagnostic clinical criteria were described by Somer (40). It is one of the rare Mendelian syndromes with infantile spasms. Haltia and Somer found uniform neuropathological changes with severe neuronal loss in the inner granular layer of the cerebellum in postmortem studies of eight patients (Haltia and 40). Neuropathologically, the disorder was referred to as "infantile cerebello-optic atrophy."

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