Concurrent bilateral temporal lobe pathology and unilateral oligodendroglioma in a dog with status epilepticus.

An eight-year-old female spayed boxer was presented in acute convulsive status epilepticus (SE). Blood gas analysis and serum biochemistry revealed mild metabolic acidosis [pH 7·3, reference interval (RI) 7·35 to 7·45, bicarbonate 13 mmol/L, RI 18 to 24] and mild azotaemia (creatinine 203 μmol/L, RI 35 to 106). The complete blood count and the cerebrospinal fluid analysis were unremarkable. Brain magnetic resonance imaging (MRI) showed bilateral T2 and FLAIR hyperintensity of both temporal lobes, more severely on the left side, and mildly enlarged lateral ventricles (Fig 1). There was no contrast enhancement present. According to the World Health Organisation animal grading system (Koestner and others 1999) histopathological examination revealed oligodendroglioma (Fig 2A) in the left temporal and piriform lobes accompanied by status spongiosus, capillary proliferation, disseminated microbleeding, gliosis and neuronal necroses in adjacent structures. Moderate oedema and gliosis was evident in the right hippocampus and temporal lobe (Fig 2B). According to Young and others (2011), cortical thickening and peripheral localisation may be suggestive for oligodendrogliomas; however, the main MRI-diagnosis in the present case was suggestive of bilateral temporal lobe oedema. MRI and histopathological examination of canine and feline patients with acute seizures have produced similar findings in the piriform and temporal lobes (Melemma and others 1999, Mariani and others 2001, Vanhaesebrouck and others 2012). SE may cause brain damage through a variety of mechanisms such as excitotoxic effects, hypoxia, lactic acidosis and ischaemia. Some neurons of the temporal lobe are known to be highly vulnerable to SE (Sommer 1880). With the present case, the authors would like to emphasise that seizure-induced temporal lobe changes can mask the primary pathology even when high-field (1·5 T) MRI is used. For better diagnosis it is recommended to repeat the imaging after the decrease of seizureinduced changes.