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Brain Bioelectric Activity

Eosinophilic Meningoencephalitis in a Dog

An American Staffordshire terrier, 1yr 8mth, presented with a 4-week history of subacute progressive signs of abnormal behaviour, ataxia on all four limbs, and blindness.

Transverse images show a T2W hyperintense to grey matter, FLAIR hyperintense, T1W iso / hypointense signal bilaterally affecting the submeningeal cortical grey matter. The cerebral sulci appear grossly enlarged with a reduction in the size of the cortical gyri. Following gadolinium administration, there is mild patchy contrast uptake affecting both the pachymeninges and leptomeninges. There is an absent septum pellucidum and the lateral ventricles are moderately enlarged. CSF analysis on this dog revealed marked pleocytosis with 93% eosinophils (see attached top left-sided image courtesy of Idexx laboratory). Infectious titres, including serology and PCR, as well as culture for prototheca were negative.

In reported cases, histopathology was consistent with severe eosinophilic and macrophagic inflammation, resulting in diffuse meningitis and atrophy or necrosis of the cortical grey matter. It is suspected that the migration of eosinophils via the meningeal vasculature into the meninges and cerebral cortex leads to an inflammatory response and neuronal necrosis of the superficial cerebral cortex.

Courtesy  of Koen Santifort, Iris van Soens and Niklas Bergknut from Evidensia Small Animal Hospital Hart van Brabant Waalwijk

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