Intracranial arachnoid cyst

14 Intracranial arachnoid cyst


Haematology and biochemistry were normal. Post-prandial serum bile acid measurement is a sensitive detector of liver dysfunction and disruption of enterohepatic circulation from a portosystemic shunt. The bile acid stimulation test in this dog was normal. Lack of response to treatment for a suspected portosystemic shunt (PSS) helped to rule out this disease as a probable cause of the clinical signs. The neurological deficits on examination rule out a psychological cause for the circling. Cerebral malformation or inflammation is most likely at that age.

Encephalitis was a possibility. Canine distemper may cause neurological signs in the immunocompromised (e.g. young or unvaccinated) dog several weeks after infection. This acute CNS inflammation results from direct viral injury. Those able to contain the infection and avoid acute inflammation may go on to develop neurological signs later in life. A chronic encephalitis results and is caused by an inflammatory response and subsequent demyelination. Distemper may produce acute encephalitis 1–2 weeks after immunization, with a modified live virus (MLV) vaccine. Neurological signs are variable. Myoclonus is a common sequela.

Necrotizing encephalitis in the Yorkshire terrier typically appears between 1 and 10 years of age, resulting in cerebral and brainstem signs which worsen over several months. The signs in this case appeared to be static. The dog had been vaccinated and had not travelled outside the UK.

MRI of the head found a quadrigeminal cistern arachnoid cyst and enlargement of the lateral and third ventricles. The enlarged cistern may have compressed the midbrain aqueduct, causing secondary dilation of the third and lateral ventricles. CSF cell count, cytology and total protein level were normal.

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Sep 3, 2016 | Posted by in SMALL ANIMAL | Comments Off on Intracranial arachnoid cyst

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