Magnetic resonance imaging of cerebral cortical necrosis (polioencephalomalacia) in a dog

A 3-year-old neutered female mixed breed dog was examined because or severe , generalized seizure activity, tetraparesis. and encephalopathic signs. Ce rebrospinal fluid (CSF) evaluation was unremarkable except for a mild incre ase in protein. Serum and CSF titers for infectious diseases were negative. Magnetic resonance (MR) imaging examination of the brain was performed and lesions were found within the cerebral gray matter of the temporal and par ietal lobes. The lesions had increased signal intensity on T1, T2, and prot on density-weighted images. There was mild inhomogeneous enhancement follow ing intravenous contrast medium administration. Neurologic status improved and the seizures were well controlled, but the dog never regained normal me ntation and euthanasia was performed 10 weeks after initial evaluation. At necropsy, severe cerebral cortical necrosis was found in the regions corres ponding to the lesions seen on MR imaging examination. Large numbers of fat -containing macrophages (gitter cells) were found within these areas, and a re thought to be responsible for the characteristic hyperintensity seen on the MR images.