Hydrocephalus

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Domestic shorthair kitten with congenital hydrocephalus. Note the obvious domed skull

Hydrocephalus is a rare neurological disease of cats characterized by an increase in the volume of cerebrospinal fluid (CSF).

The cerebral ventricles in the brain are cavities filled with cerebrospinal fluid (CSF). The deformation of the ventricular system is related to diseases such as hydrocephalus and edema but may also occur as the result of a space occupying lesion. Together with the compression of the white matter adjacent to the ventricles, these diseases can cause serious neurological problems including cognitive impairment and even death[1].

There are two forms of hydrocephalus in cats:

  • Compensatory hydrocephalus - due to loss of normal parenchyma - e.g. cerebral atrophy secondary to an infarct, hypoplasia or atrophy associated with feline panleukopenia
  • Obstructive hydrocephalus - congenital or acquired - interference with CSF circulation due to mesencephalic aqueductal stenosis, quadrigeminal arachnoid cysts[2][3], meningoencephalocoele (seen with use of griseofulvin during pregnancy), syringmyelia formation[4], or a failure of arachnoid villi development - usually FIP, Cryptococcus spp meningoencephalitis, lymphoma, choanal atresia[5], etc[6].

Congenital obstructive hydrocephalus is often associated with an abnormal dome shaped cranium that includes an enlarged cranial cavity and a thin calvaria with open sutures. The bony orbits are also enlarged and the eyeballs exhibit a ventroalateral strabismus probably as a consequence of the orbital malformation rather than compression of the oculomotor nerves.

Clinical symptoms in affected cats usually relate to disturbances of the prosencephalon (forebrain), including behavioral changes, ataxia, mental depression, blindness and seizures[7]. As the disease progresses, the cat becomes progressively moribund.

Hydrocephalus is thought to play a role in the development of hypodypsic hypernatremia in cats[8].

Hydrocephalus may be confirmed by radiographic demonstration of enlarged lateral ventricles. Plain radiography will often reveal a homogenous ground glass appearance throughout the cranial cavity. Cranial sutures and/or open fontanelles may be evident after the normal age for closure and skull ossification. Ultrasonography may be performed through open fontanelles[9], CT, or MRI are the most useful diagnostic aids[10].

Collection of CSF for analysis is usually not performed since it may precipitate brain herniation due to the presence of increased intracranial pressure.

A differential diagnosis would include craniosynostosis.

The management of hydrocephalus depends upon establishing the cause. Many cases are not amenable to treatment.

A ventriculoperitoneal shunt has been used to treat cats with hydrocephalus[11]. Common complications include catheter blockage and sepsis.

Dexamethasone, administered at an oral dose of 1 mg/kg daily, has been used empirically with some success.

Medical therapy can provide temporary relief but definitive treatment usually involves placement of a ventriculoperitoneal shunt[12].

References

  1. Liu F et al (2009) Model-based estimation of ventricular deformation in the cat brain. Med Image Comput Comput Assist Interv 12(2):308-315
  2. Lowrie M et al (2009) Quadrigeminal cyst management by cystoperitoneal shunt in a 4-year-old Persian cat. J Feline Med Surg 11(8):711-713
  3. Reed S et al (2009) Quadrigeminal arachnoid cysts in a kitten and a dog. J Vet Diagn Invest 21(5):707-710
  4. Okada M et al (2009) MRI of secondary cervical syringomyelia in four cats. J Vet Med Sci 71(8):1069-1073
  5. Azarpeykan S et al (2013) Choanal atresia in a cat. N Z Vet J Jan 7
  6. Barnett, KC & Crispin, SM (2002) Feline Ophthalmology: An atlas & text. WB Saunders, London
  7. de Lahunta A, Cummings J. (1965) The clinical and electroencephalographic features of hydrocephalus in three dogs. J Am Vet Med Assoc 146:954-964
  8. Dow SW, Fettman MJ, LeCouteur RA, et al (1987) Hypodipsic hypernatremia and associated myopathy in a hydrocephalic cat with transient hypopituitarism. J Am Vet Med Assoc 191:217-221
  9. Rivers WJ, Walter PA. (1992) Hydrocephalus in the dog: utility of ultrasonography as an alternate diagnostic imaging technique. J Am Anim Hosp Assoc 28:333-343
  10. Karkkainen M. (1995) Low- and high-field strength magnetic resonance imaging to evaluate the brain in one normal dog and two dogs with central nervous system disease. Vet Radiol Ultrasound 36:528-532
  11. Ori J, Yamaguchi T, Komiya M, et al (1997) Two cases of feline hydrocephalus treated by ventriculoperitoneal shunt. J Jap Vet Med Assoc 50:599-602
  12. Thomas WB (2010) Hydrocephalus in dogs and cats. Vet Clin North Am Small Anim Pract 40(1):143-159