Abstracts

The mechanisms underlying the Hemiconvulsion-Hemiplegia-Epilepsy (HHE) are unclear. The current proposed pathogenic mechanism is a neuronal injury induce by venous thrombosis and/or hypoxia. Previous abnormalities of the brain were suggested as underlying mechanism. We report a patient with HHE who presented acutely. Unfortunately, the patient died. With the data of neuroimaging and neuropathological studies, we discuss the possible pathophysiology of the HHE and possible therapeutic implications A 17-months-old girl with 2 days history of fever and treatment with acetaminophen presented a prolonged status epilepticus. She had no particular medical history. The day of her referral, she was found by her mother to be unresponsive and having left hemiconvulsion. The patient was found in the morning ( 6 hours without surveillance). She was given diazepam, phenytoin, phenobarbital and thiopental who permitted to stop the seizure. She was intubated and transferred in pediatric intensive care unit. Initial EEG showed right predominant periodic spikes and slow spikes (1 Hz). Routine laboratory investigations and CSF analysis were normal. Cranial CT the day of admission revealed neither edema nor abnormal tissue densities. At day 2, a right hemiplegia was noted. The EEG revealed right pseudoperiodic spike-wave complexes. MRI performed 5 days after admission displayed an abnormally high signal in the right hemispheric white matter in the diffusion-weighted and T2-weighted images. At day 5, EEG was characterized by a progressive decrease of cortical activity. At day 6, the patient presented a decrease of blood pressure, an areactive coma without bulbar reflexes. The EEG confirmed the cerebral dead. A neuropathological study was performed (immunochemistery, ultrastuctural analysis) The neuropathological studies confirmed a right homogenous hemispheric edema. There were neither thrombus nor cellular inflammatory response. There was no malformation in limbic or cortical structures. We observed axonal damages in the right thalamus The abnormalities in diffusion-weighted imaging indicate cytotoxic edema of the epileptic hemisphere confirmed by the neuropathological studies. The neuropathological studies suggest that the edema is responsible of neuronal death. In HHE, we suggest cell damages induce by edema as possible pathophysiological mechanism. The thalamic dysfunction induced by cell damages can be responsible of an disrutpion of thalamo-cortical circuit and can play a role in the latter epilepsy. In acute presentation, the use of anti-edema therapy should be discuss to prevent the cell injury.
The neuropathological studies will be presented in details.