Hydrocephalus

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Sections available in full article Introduction, Presenting signs, Acute presentation, Age predisposition, Breed predisposition, Cost considerations, Special risks (e.g. anesthetic), Pathogenesis, Etiology, Predisposing factors, Pathophysiology, Timecourse (incubation, duration), Diagnosis, Client history, Clinical signs, Diagnostic investigation, Confirmation of diagnosis, Gross autopsy findings, Histopathology findings, Differential diagnosis, Treatment, Standard treatment, Monitoring, Sequelae, Prognosis, Expected response to treatment, Reasons for treatment failure, Sources, Publications, Vetstream contributor(s),
Contributors Dr Rodney Bagley DVM DipACVIM

Introduction

  • Cause : may be congenital or acquired Hydrocephalus: congenital.
  • Typically seen in brachycephalic breeds.
  • Signs : paresis, blindness and seizures in puppies.
  • Diagnosis : ultrasound, advanced imaging.
  • Treatment : surgical shunting, anticonvulsants, corticosteroids.

Diagnosis

Clinical signs

  • Clinical signs of hydrocephalus reflect the anatomical level of disease involvement.
  • Forebrain, vestibular, and cerebellar signs are most common.
  • Severity of clinical signs is not necessarily dependent upon the degree of ventricular dilation, but rather on a host of concurrent abnormalities including the underlying disease process, associated intracranial pressure changes, intraventricular hemorrhage, and the acuity of ventricular obstruction.
  • In young dogs prior to ossification of the cranial sutures, hydrocephalus may contribute to abnormalities of skull development such as:
    • A thinning of the bone structure.
    • A dome-shaped or bossed appearance to the head.
    • Persistent fontanelles.
  • A ventral and/or lateral strabismus has been noted in humans and animals with hydrocephalus. This may be referred to as the "setting-sun sign". Confusion remains as to the underlying reason for this clinical findings. Some have suggested that this appearance is associated with the skull deformity and distortion of the orbits. Others suggest that because this abnormality can be improved with shunting on the lateral and third ventricles that this strabismus is associated with pressure on the mesencephalic tegmentum.
  • As the forebrain structures are often involved with hydrocephalus, alterations in awareness and cognition are common.

Diagnosis

Differential diagnosis

  • Portosystemic shunts Portosystemic shunt.
  • Trauma.
  • In young dogs (<1 year of age), other considerations for intracranial disease include:
    • Encephalitis Encephalitis.
    • Other congenital brain defects.
    • Inherited degenerative diseases, eg abiotrophies and storage diseases Storage disease.
  • In middle-aged to older dogs:
    • Brain tumors Brain: neoplasia.
    • Encephalitis Encephalitis.

Sequelae

Prognosis

  • If the clinical signs are adequately controlled, prognosis may be good.
  • If there is no resolution of the profound neurological deficits, the disease may be terminal.

Expected response to treatment

  • Improving clinical demeanor.
  • Medical treatment will only provide temporary relief of signs.

Reasons for treatment failure

  • Medical management unlikely to be successful in long-term.
  • Undershunting due to blockage or disconnection of catheter.
  • Complications associated with shunt, eg infection.

Sources

Publications

Refereed papers

  • Hudson J A, Simpson S T, Buxton D F, Cartee R E et al(1990) Ultrasonographic diagnosis of canine hydrocephalus. Vet Rad 31 , 50-58.
  • Spaulding K A & Sharp N J H (1990) Ultrasonographic imaging of the lateral cerebral ventricles in the dog. Vet Rad 31 , 59-64.
  • Hudson J A, Cartee R E, Simpson S T & Buxton D F (1989) Ultrasonographic anatomy of the canine brain. Vet Rad 30 , 13-21.
  • Simpson S T & Reed R B (1987) Manometric values for normal cerebrospinal fluid pressure in dogs. JAAHA 23 , 629-632.
  • Kay N D, Holliday T A, Hornof W J & Gomez J (1986) Diagnosis and management of an atypical case of canine hydrocephalus, using computed tomography, ventriculoperitoneal shunting, and nuclear scintigraphy. JAVMA 188 , 423-426.
  • Whittle I R, Johnston I H & Besser M (1985) Intracranial pressure changes in arrested hydrocephalus. J Neurosurg 62 , 77-82.
  • Rosenberg G A, Saland L & Kyner W T (1983) Pathophysiology of periventricular tissue changes with raised CSF pressure. J Neurosurg 59 , 606-611.
  • Klemm W R & Hall C L (1971) Electrocephalograms of anesthetized dogs with hydrocephalus. Am J Vet Res 32 , 1859-1864.
  • Gage E D (1970) Surgical treatment of canine hydrocephalus. JAVMA 157 , 1729-1740.
  • Few A B (1966) The diagnosis and surgical treatment of canine hydrocephalus. JAVMA 149 , 286-293.
  • deLahunta A & Cummings J F (1965) The clinical and electroencephalographic features of hydrocephalus in three dogs. JAVMA 146 , 954-964.
  • Rivers W J & Walter P A Hydrocephalus in the dog - Utility of ultrasonography as an alternative diagnostic imaging technique.

Other sources of information

  • Greenberg M S (1991) Treatment of Hydrocephalus. In: Handbook of Neurosurgery. Lakeland, FL, Greenberg Graphics. pp 200-218.
  • Adams R D & Victor M (1989) Disturbance of cerebrospinal fluid circulation, including hydrocephalus and meningeal reactions. In: Principle of Neurology. 4th edn, New York: McGraw Hill. pp 501-515.
  • Simpson S T (1989) Hydrocephalus. In: Kirk R W (ed): Current Veterinary Therapy X. Philadelphia, W B Saunders. pp 842-847.
  • Simpson S T & Reed R B (1987) Cerebrospinal fluid pressure in dogs -Technique, normal values and meaning. Proceeding 5th ACVIM. pp 275-276.
  • deLahunta A (1983) In: Veterinary Neuroanatomy and Clinical Neurology. 2nd edn, Philadelphia: W B Saunders.

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