OBJECTIVE: Acute disseminated encephalomyelitis (ADEM) is a rare acute inflammatory-demyelinating disease of central nervous system (CNS) that is triggered by viral infection and vaccination. It causes various symptoms of CNS or spinal cord such as consciousness disorder, visual disturbance, dysfunction of bladder and bowel. we report a case that had poor imaging findings and had difficulty in diagnosis to emphasise that a certain number of ADEM cases have delayed the appearance of imaging findings.
CASE: 14-year-old girl. About 2 weeks after administration of the 3rd Japanese encephalitis vaccine, she had fever and urinary retention. She was hospitalized on the 7th disease day. Suspecting ADEM, head and lumbar spine MRI was performed no abnormal findings. Cerebrospinal fluid examination showed mononuclear cell-dominated cell number increase and we diagnosed as Meningitis-Retention Syndrome. When treatment was started with fluid replacement, acyclovir, urinary retention symptoms tended to improve, however fever continued. Although head MRIs were performed a few times, no abnormal findings were found. Double vision, extraocular muscle paralysis and a tendency toward somnolence were observed from the 21st disease day. We clinically diagnosed as ADEM, and methylprednisolone pulse therapy was taken on the 24th disease day. Those symptoms were improved dramatically and immediately, we did 2 courses of pulse therapy. A high-signal lesion was found in the white matter on the head MRI FLAIR image performed on the 36th disease day, and we diagnosed as ADEM. She was discharged on the 38th disease day without relapse or sequelae.
CONCLUSION: In this case, because the appearance of imaging findings was late on the 36th disease day, it was difficult to diagnose. A certain number of ADEM reports have delayed the appearance of imaging findings, it is important to keep this disease in mind to start treatment immediately.