Clarification of the characteristics of biphasic encephalopathy in children

Abstract

Objectives: To clarify the characteristics of biphasic encephalopathy, and to determine if we can differentiate biphasic encephalopathy from monophasic encephalopathy before the second phase.
Methods: Characteristics of children diagnosed with biphasic encephalopathy were retrospectively investigated from April 2007 to August 2009. (2) The maximum value of lactate dehydrogenase (LDH), fibrin/fibrinogen degradation products (FDP), and D-dimer concentration was compared in 10 children with biphasic encephalopathy, 26 children in the monophasic encephalopathy group, and 10 children with febrile convulsion or epilepsy until third day.
Results: (1) Thirty-six patients were diagnosed with encephalopathy; among them, 10 (28%) had biphasic encephalopathy. Twenty-two cases had seizure onset in status epilepticus; among them, 8 patients (36%) had biphasic encephalopathy. In all cases, the first symptoms were generalized tonic-clonic seizures. In 8 cases, the seizure was prolonged (more than thirty minutes); in 2 cases, the seizure resolved within thirty minutes. The median time of second seizure occurrence or consciousness deterioration was 5 days (4-8 days). Intracranial pressure was managed using the intracranial pressure sensor and treatment was carried out by administering steroid pulse therapy and/or hypothermia therapy. Aggressive treatment was administered to 2 of 10 patients upon the first seizure, but the occurrence of a second phase was not prevented in all 10 patients. All children survived. One child had no neurological sequelae, 5 children had mild, and 4 children had severe neurological sequelae. (2) For LDH, a significant difference was found between the febrile convulsion or epilepsy group and encephalopathy (p=0.017 and 0.002, respectively), and for FDP and D-dimer, a significant difference were found between the febrile convulsion or epilepsy group and the biphasic encephalopathy group (p=0.018 and 0.033, respectively). No markers detected a difference between monophasic encephalopathy and biphasic encephalopathy before the second phase.
Conclusion: There are frequent poor outcomes among children with encephalopathy in whom convulsions and loss of consciousness recur after a transient improvement following an initial seizure. We cannot differentiate biphasic encephalopathy from monophasic encephalopathy before the second phase. After convulsions in children, we need to consider the possibility of biphasic neurological symptoms.