Article
Epilepsy, hippocampal sclerosis and amygdalar atrophy as remote complications of H1N1-influenza-associated encephalopathy in an adult
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Published: | August 25, 2015 |
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A number of clinical cases of H1N1 influenza associated encephalitis (H1N1-IAE) have been reported in the pediatric literature, but very few cases have been described in adults, and none describe neuropathologic features. A wide range of neurological complications were previously reported among survivors of H1N1-IAE, including altered mental status, febrile seizures, ophthalmoparesis, quadriparesis, delayed Parkinsonism, encephalitis lethargica and many more subtle neurologic changes. The neuropathological findings of H1N1-IAE are limited to autopsies from cases of acute fatal encephalopathy. Most of the described neuropathological findings in H1N1-IAE are acute to subacute morphologic changes, including edema, inflammation, necrosis, fibrin thrombi, endothelial injury, hemorrhage, neuronal loss, gliosis, and axonal injury. The patient was an ICU nurse with H1N1-IAE during the H1N1 pneumonia epidemic of 2009, resulting in intractable temporal lobe epilepsy. Imaging revealed atrophy of hippocampus, amygdala and temporal lobe. The patient had an anterior temporal lobectomy and the specimen showed marked hippocampal neuronal loss and reactive gliosis, suggestive of hippocampal sclerosis. Sections from right temporal lobe and amygdala revealed extensive gliosis and some perivascular lymphocytic cuffing. Prior experimental studies in animal models of H1N1-IAE have demonstrated inflammatory reactions and morphologic changes. The clinical, radiological and neuropathological findings in this patient are compatible with hippocampal sclerosis and amygdalar atrophy as remote complications of H1N1-IAE.
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