Dados do Trabalho

Título

Development of hippocampal sclerosis after posterior reversible encephalopathy syndrome

Apresentação do caso

Case presentation: A 18-year-old man was evaluated for surgical treatment of pharmacoresistant epilepsy. At age six he was diagnosed with acute myeloid leukemia after severe anemia, fever, and frequent vomiting. Three years later he underwent conditioning chemotherapy with fludarabine, cyclophosmide, steroids, and total body irradiation, followed by an allogeneic bone marrow transplant from umbilical cord blood. Ten days after transplantation, he presented a skin rash on the face and upper body. A cerebrospinal fluid PCR revealed human herpes virus type 6 (HHV-6) infection, treated with acyclovir. Five days later, he had a sudden hypertensive symptoms, followed by low blood saturation, dizziness, and mental confusion, evolving to a five minutes tonic-clonic seizure. Seizure was aborted with 15 mg/kg venous hydantal. An MRI exam evidenced hyperintense corticosubcortical lesions in the bilateral parietal lobes, which reverted 30 days after symptoms’ onset without any neurological deficits, thus compatible with a posterior reversible encephalopathy syndrome (PRES). However, at age 11 he started presenting weekly to daily episodes of behavioral arrest, staring, oromastigatory automatisms, and ictal aphasia, sometimes evolving with cephalic version to the right, upper and lower limb hypertonia and bladder release. Seizures were resistant to oxcarbazepine and clobazam. Brain MRI showed left hippocampal atrophy, without other brain abnormalities. Video-EEG monitoring revealed frequent left anterior temporal focal spikes beginning at the same topology, and the neuropsychological test showed mild deficits in verbal memory, suggesting left temporal lobe involvement. He underwent left amygdalohippocampectomy and has been seizure free since surgery, with a current follow-up of six months. The histopathological evaluation revealed a type 1 hippocampal sclerosis (HS) without signs of viral inclusions.

Discussão

Discussion: HS type 1 is the most frequent etiology of adult-onset temporal lobe epilepsy. Although the most frequent etiologies for HS are prolonged seizures, hypertensive encephalopathy may have led to hippocampal damage by vascular mechanisms. While we cannot exclude that HS may have resulted from the HHV6 viral infection, the lack of viral inclusions suggests PRES as the etiology of HS and chronic TLE within four years.

Comentários finais

Concluding remarks: This indicates a triggering role of PRES in the development of hippocampal sclerosis.