2596

PATHOLOGICAL AND VIROLOGICAL FINDINGS OF INFLUENZA ASSOCIATED ACUTE ENCEPHALOPATHY IN JAPANESE CHILDREN

Togashi T¹, Matsuzono Y² , Morishima T³ , Narita M⁴

¹Sapporo City General Hospital, Sapporo, Japan

²Matsuzono Pediatric Clinic, Sapporo, Japan

³Nagoya University, Nagoya, Japan

⁴Sapporo JR Hospital, Sapporo, Japan

Objective: To investigate the etiology of acute encephalopathy during influenza epidemics in Japanese children.

Methods: Post-mortem examination was performed pathologically and virologically in two patients with this disease who died with a rapid and fulminant course.

Results: Disseminated edema, vascular damage with subsequent leakage of plasma protein and intravascular formation of thrombus were observed in the upperpart of spinal cord and in the brain stem. Interstitial pneumonia was observed in both cases. Intravascular thrombus formation in the lungs and intestinal destruction were observed in one case. Influenza virus genome, H3, was detected by PCR in a CSF sample of one case and influenza-A specific antigen was detected using a monoclonal antibody against NP polypeptide in the bronchial epithelial cells of another case. Despite the pathological changes in the spinal cord and the brain stem, no virus, no virus antigen, no virus genome have been detected in these materials. Cytokines such as IL-6 and TNF-α were markedly elevated in CSF and serum samples of one case.

Conclusion: These findings strongly suggest the damage of the endothelial cells of systemic vessels and the destruction of the blood-brain barrier with the activation of coagulation system. This must have resulted in the leakage of plasma protein and the intravascular formation of thrombus in the brain, and consequently, the patients with this disease, with or without convultion, fell into coma along with haemorrhagic diathesis.