Human Herpesvirus 6–Associated Encephalopathy in a Child with Dravet Syndrome

Abstract

Dravet syndrome presents with generalized and unilateral clonic or clonic–tonic seizures that occur during the first year of life, followed by severe epilepsy. Prolonged seizures are often provoked by fever and usually followed by recovery of the previous condition. We describe the case of a 13-month-old girl with Dravet syndrome who experienced severe neurological sequelae as a result of human herpesvirus 6–associated encephalopathy. Biphasic clinical course was observed, with fever and prolonged seizures at onset and late seizures refractory against antiepileptic agents. Serum concentrations of proinflammatory cytokines and matrix metalloproteinase-9, which have been associated with development of acute encephalopathy, were not markedly increased in this patient, suggesting that these molecules were not the main causes of neuronal damage in this patient. Instead, seizure susceptibility due to SCN1A mutation may have contributed to acute encephalopathy in our patient.

Keywords

Dravet syndrome - human herpesvirus 6 - encephalopathy

• References

• 1 Dravet C, Bureau M, Oguni H, Fukuyama Y, Cokar O. Severe myoclonic epilepsy in infancy (Dravet syndrome). In: Roger J, Bureau M, Dravet C, Genton P, Tassinari CA, Wolf P, , eds. Epileptic Syndromes in Infancy, Childhood and Adolescence, 4th ed. London: John Libbey Eutotext Ltd.; 2005: 89-113
• 2 Nagasawa T, Kimura I, Abe Y, Oka A. HHV-6 encephalopathy with cluster of convulsions during eruptive stage. Pediatr Neurol 2007; 36 (1) 61-63
• 3 Okumura A, Uematsu M, Imataka G , et al. Acute encephalopathy in children with Dravet syndrome. Epilepsia 2012; 53 (1) 79-86
• 4 Oguni H, Hayashi K, Awaya Y, Fukuyama Y, Osawa M. Severe myoclonic epilepsy in infants—a review based on the Tokyo Women's Medical University series of 84 cases. Brain Dev 2001; 23 (7) 736-748
• 5 Chipaux M, Villeneuve N, Sabouraud P , et al. Unusual consequences of status epilepticus in Dravet syndrome. Seizure 2010; 19 (3) 190-194
• 6 Christophe C, Fonteyne C, Ziereisen F , et al. Value of MR imaging of the brain in children with hypoxic coma. AJNR Am J Neuroradiol 2002; 23 (4) 716-723
• 7 Ichiyama T, Morishima T, Kajimoto M, Matsushige T, Matsubara T, Furukawa S. Matrix metalloproteinase-9 and tissue inhibitors of metalloproteinases 1 in influenza-associated encephalopathy. Pediatr Infect Dis J 2007; 26 (6) 542-544
• 8 Ichiyama T, Ito Y, Kubota M, Yamazaki T, Nakamura K, Furukawa S. Serum and cerebrospinal fluid levels of cytokines in acute encephalopathy associated with human herpesvirus-6 infection. Brain Dev 2009; 31 (10) 731-738
• 9 Ichiyama T. Acute encephalopathy/encephalitis in childhood: a relatively common and potentially devastating clinical syndrome. Brain Dev 2010; 32 (6) 433-434
• 10 Mizuguchi M, Yamanouchi H, Ichiyama T, Shiomi M. Acute encephalopathy associated with influenza and other viral infections. Acta Neurol Scand 2007; 115 (4, Suppl) 45-56
• 11 Takanashi J, Oba H, Barkovich AJ , et al. Diffusion MRI abnormalities after prolonged febrile seizures with encephalopathy. Neurology 2006; 66 (9) 1304-1309 , discussion 1291
• 12 Ogiwara I, Miyamoto H, Morita N , et al. Nav1.1 localizes to axons of parvalbumin-positive inhibitory interneurons: a circuit basis for epileptic seizures in mice carrying an Scn1a gene mutation. J Neurosci 2007; 27 (22) 5903-5914
• 13 Suga S, Suzuki K, Ihira M , et al. Clinical characteristics of febrile convulsions during primary HHV-6 infection. Arch Dis Child 2000; 82 (1) 62-66
• 14 Hoshino A, Saitoh M, Oka A , et al. Epidemiology of acute encephalopathy in Japan, with emphasis on the association of viruses and syndromes. Brain Dev 2012; 34 (5) 337-343