hydrocephaly – unilateral

hydrocephaly – unilateral


this refers to unilateral cerebral ventriculomegaly which arises secondary to functional or congenital obstruction of the foramen of monro, impeding effective passage of cerebrospinal fluid (csf) from the affected lateral ventricle. hydrocephaly ex vacuo, secondary to parenchymal degeneration, is to be considered as a manifestation of porencephaly. congenital obstruction is caused by stenosis, atresia, or more rarely agenesis of monro’s foramen; functional obstruction may be seen secondary to intraventricular haemorrhage or intracranial tumours which directly affect the patency of the foramen. the condition is not common, and only a handful of cases have been described prenatally.


this diagnosis has only been reported in the third trimester. the principal sonographic finding is unilateral dilatation of the cerebral ventricles (lateral atrial diameter greater than 12mm; dependency of the choroid should also be appreciated). the unilateral nature can only be confirmed by careful inspection of the contralateral ventricle, which should retain normal dimensions. this may be difficult to visualize if the affected ventricle is furthest away in the transverse plane, as reverberation artefact may preclude effective assessment of the nearside ventricle. coronal views may therefore be helpful; in the third trimester, vaginal scanning should be useful in this respect. the remainder of the ventricular system should also appear normal. ipsilateral cortical thinning and midline shift secondary to pronounced ventriculomegaly has been reported, as has frontal encephalocele; the condition does not appear to be associated with any syndromic or remote abnormalities, possibly reflecting the localised nature of the lesion. for these reasons, karyotyping would not appear mandatory.

differential diagnosis

unilateral porencephaly may also present with similar sonographic findings, and may indeed represent a form of hydrocephaly ex vacuo, but the presence of appreciable midline shift will indicate the diagnosis of unilateral hydrocephaly. a large arachnoid cyst may also present with a unilateral intracranial cystic mass with midline shift, but dependent choroid will not be evident within it.

sonographic features

unilateral cerebral ventriculomegaly.

normal dimensions of contralateral cerebral ventricle, 3rd and 4th ventricles.

ipsilateral cortical thinning.

midline shift.

associated syndromes

  • aminopterin
  • aminopterin-likeamniocentesis
  • aniridia-renal anomalies
  • anophthalmia-abnormal nares
  • anophthalmia-cleft lip/palate
  • aqueduct stenosis-basilar impression
  • basal cell nevus
  • beemer: dense bones
  • bijlsma: aqueduct stenosis
  • bone fragility-proptosis
  • campomelia-aankyloglossia
  • cataract-ossified pinnae
  • centromere instability-immunodeficiency
  • cerebroarthrodigital
  • charge association
  • chromosome
  • ciliary akinesia/dyskinesia
  • clefting-corneal opacity
  • crouzon
  • daish: tall stature-joint hypermobility
  • de hauwere: iris dysplasia
  • epidermal nevus syndrome
  • fine: ocular anomalies-cleft palate-asymmetry
  • fraser: cryptophthalmos
  • goldenhar
  • habel: microstomia-hydrocephalus
  • hajdu-cheney
  • hanhart: hypoglossia-hypodactyly
  • heptacarpo-octatarso-dactyly
  • hydrocephalus-endocardial fibroelastosis-cataracts
  • hydrocephalus-proliferative vasculopathy
  • hydrolethalus
  • jeune thoracic dysplasia
  • masa
  • mulibrey nanism
  • neurocutaneous melanosis
  • neurofibromatosis
  • ochoa: urofacial syndrome
  • osteogenesis imperfecta, lethal type
  • osteoglophonic dwarfism
  • oto-palato-digital ii
  • palmer-pagon: hydrocephalus-low umbilicus
  • petersí-plus
  • pfeiffer: synostosis-deafness
  • pseudomarfanismrenal cysts
  • rhizomelic chondrodysplasia-thrombocytopenia
  • rogers: anophthalmia
  • schinzel-giedion: dwarfism
  • sengers: obesity-hypogenitalism
  • thakker-donnai
  • tibial aplasia-ectrodactyly
  • trigonocephaly
  • van biervliet: thoracic dystrophy
  • vater
  • vacterl
  • waaler: costovertebral dysplasi
  • -warburg
  • weaver: craniosynostosis
  • winter: thoracic dysplasia
  • winter-wigglesworth: cerebro-renal
  • x linked-unusual facies-callosal agenesis


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