= DE MORSIER SYNDROME

[Georges de Morsier (1894–1982), professor of neurology and director of the neurological clinic of the university of Geneva, Switzerland]

= rare anterior midline anomaly with

1. Hypoplasia of optic nerves
2. Hypoplasia / absence of septum pellucidum

• Often considered a mild form of lobar holoprosencephaly

Cause: insult between 5–7^th week of GA; M÷F = 1÷3

Associated with: schizencephaly (50%)

• hypothalamic hypopituitarism (66%):
  diabetes insipidus (in 50%), growth retardation (← deficient secretion of growth hormone + thyroid stimulating hormone)
• diminished visual acuity (hypoplasia of optic discs), nystagmus, occasionally hypotelorism; seizures, hypotonia
• small optic canals
• hypoplasia of optic nerves + chiasm + infundibulum
• dilatation of chiasmatic + suprasellar cisterns
• fused dilated boxlike frontal horns squared off dorsally + pointing inferiorly
• bulbous dilatation of anterior recess of 3^rd ventricle
• hypoplastic / absent septum pellucidum
• thin corpus callosum