Equis ISSN 2398-2977

Hydrocephalus

Synonym(s): Hydrocephalus internus congenitus Hydranzephalia

Contributor(s): Graham Munroe, Jonathan Pycock, Katrin Schmallenbach

Introduction

  • Abnormal increase in quantity of cerebrospinal fluid (CSF) in the brain.
  • Most commonly seen in neonatal foals (congenital), although may be acquired in the older animal.
  • Signs: grossly domed skull (neonate), may be other defects.
  • Diagnosis: clinical signs.
  • Treatment: none.
  • Prognosis: grave.

Pathogenesis

Etiology

  • Congenital or acquired.
  • Cause unknown: possibly hypoplasia or obstruction of the conducting and/or absorbing channels for CSF in the ventricles and/or subarachnoid space.
  • Possible genetic predisposition but mode of inheritance has not yet been determined.

Pathophysiology

  • Increased CSF volume within the ventricular system (internal hydrocephalus) or subarachnoid space (external hydrocephalus).
  • Obstruction/hypoplasia of the CSF conducting channels between the ventricles (site of CSF production) and the subarachnoid space (site of CSF absorption)    →   fluid accumulation in the ventricles and/or subarachnoid space   →    increased intracranial pressure.
  • Increased intracranial pressure (hypertensive hydrocephalus)    →   deformation of skull in neonates.
  • Increased intracranial pressure    →   pressure-induced attenuation of cerebral white matter.
  • Can also be acquired in young foals following brain infections (viral/bacterial), eg bacterial meningoencephalitis, or as part of the cerebral hemorrhage found in neonatal maladjustment syndrome   Foal: neonatal maladjustment syndrome  .
  • Can occur in older animals secondary to traumatic or infectious inflammation, eg granulomatous ependymitis with equine infectious anemia   Equine infectious anemia (EIA)  or space-occupying lesions, eg neoplasia, abscess.
  • Possibly linked with cerebral malformation   Cerebellum: hypoplasia  .
  • Normotensive hydrocephalus may result from CSF passively expanding to fill the space normally occupied by brain tissue following CNS diseases such as viral encephalitis   Equine viral encephalitides  , neonatal maladjustment syndrome   Foal: neonatal maladjustment syndrome  or brain trauma   CNS: brain trauma  which causes cerebral destruction.
  • Fetal cranial enlargement may   →    dystocia in the mare   Reproduction: dystocia  .

Diagnosis

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Treatment

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Outcomes

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Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Boerma S, Back W & Sloet van Oldruitenborgh-Oosterbaan M M (2012)The Friesian horse breed: A clinical challenge to the equine veterinarian?Equine Vet Educ24(2), 66-71 VetMedResource.
  • Maulet B E B, Bestbier M, Jose-Cunilleras E, Scrine J A & Murray R (2008)Magnetic resonance imaging of a cholesterol granuloma and hydrocephalus in a horse.Equine Vet Educ20(2), 74-79 VetMedResource.
  • Welchli R O & Ehrensperger F (1988)Two related cases of cerebellar abnormality in equine fetuses associated with hydrops of fetal membranes.Vet Rec123(20), 513-514 PubMed.
  • Carbery J T (1979)A case of equine hydrocephalus.N Z Vet27(8), 158 PubMed.

Other sources of information

  • Hahn C N, Mayhew I G & Mackay R J (1999)Diseases of the Forebrain.In:Equine Medicine & Surgery. 5th edn Eds: Colahan P T, Mayhew I G, Merritt A M & Moore J N. Mosby, Missouri. pp 904-905. ISBN: 0 8151 1743 4.


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