Olfactory vector hypothesis for encephalitis lethargica.

Viruses have long been implicated in the pathogenesis of classical encephalitis lethargica, which was first described by Constantin von Economo in 1917. In this article, I propose the hypothesis that an airborne virus travels along the olfactory conduit to infect the olfactory bulb; this local infection or induced neuroinflammation, in turn, retrogradely targets certain neuronal populations with sleep-wake regulatory functions in the hypothalamus and midbrain, leading to the development of wakeful inactivity, a hallmark clinical feature of the disease. Furthermore, the olfactory vector hypothesis may also explain the pathomechanism of the debilitating complication of the disease, i.e., postencephalitic parkinsonism, in terms of a recently discovered nigro-olfactory projection.

Can fever treat epileptic encephalopathies?

PURPOSE: To describe resistant epileptic encephalopathies that significantly improved after an acute febrile episode (FE). METHODS: We reviewed the clinical history of patients with daily pharmacoresistant seizures referred to the Saint-Vincent de Paul Hospital in the last 5 years. Four patients experienced seizure arrest in relation with a febrile episode. RESULTS: The four patients suffered from epileptic encephalopathy. Three were symptomatic, one cryptogenic. They presented spasms and atypical absences, beginning after the age of 1 year. All seizures stopped at the onset of fever, and significant EEG improvement was observed. The seizure-free period ranged from 2 to 24 months. DISCUSSION AND CONCLUSION: The close link between the occurrence of FE and the disappearance of seizures and EEG improvement, contrasting with the previous pharmacoresistance of this epileptic encephalopathy, supports a non fortuitous association. Several mechanisms could explain this phenomenon, including viral etiology, hyperthermia, inflammatory-immune reaction and ACTH release. Better understanding this phenomenon could open new therapeutic perspectives.

Influenza A-associated encephalopathy with bilateral thalamic necrosis in Japan.

Two cases of acute encephalopathy in young children clearly showed evidence of influenza A virus infection and bilateral thalamic lesions. Influenza-associated encephalopathy with bilateral thalamic lesions has mostly been reported in Japan; it differs from Reye's syndrome in several respects. Other factors in addition to influenza virus infection may have contributed to the etiology of encephalopathy in our case patients.

Influenza A virus encephalopathy with symmetrical thalamic lesions.

UNLABELLED: During an epidemic of influenza A infection in Japan, a 7-year-old boy was admitted to our hospital because of high fever, convulsions, coma, and liver dysfunction on the 2nd day of a cold-like illness. His serum CPK was markedly elevated, but there was no hyperammonaemia or hypoglycaemia. His CSF showed an increased protein level, but the cell count and glucose level were normal. CT and MRI of the brain showed symmetrical thalamic lesions, and he was diagnosed with acute necrotizing encephalopathy in childhood. He had a significant increased in antibodies to influenza A H1N1 in serum and CSF, but the CSF was negative for influenza virus using virus isolation and a polymerase chain reaction assay. CONCLUSION: Antibody production without detectable levels of influenza virus in cerebrospinal fluid suggests that virus infection occurred, but the virus did not replicate in sufficient numbers in his central nervous system. The thalamic lesion, the hallmark of acute necrotizing encephalopathy in childhood, may be initiated by a local virus infection and develop with subsequent local changes such as breakdown of the blood-brain barrier and the extravasation of blood.

Hemiballismus associated with Influenza A infection.

A case of 2-year and 3-month-old boy developing right hemiballismus and transient selective unilateral involvement in the left thalamus on MRI during Influenza A infection is reported. Hemiballismus is an extremely rare neurological complication and, to our knowledge, this is the first case showing hemiballismus during Influenza A infection.