Acute Disseminated Encephalomyelitis Presenting as Rhombencephalitis: An Atypical Case Presentation

Abstract

Acute disseminated encephalomyelitis (ADEM) is a demyelinating and inflammatorycondition of the central nervous system, occurring predominantly in white matter. ADEM involving the rhombencephalon without affecting the white matter is veryrare. Here, we present an unusual case of ADEM involving only the rhombencephalonin a 4-year-old Asian girl. The patient complained of pain in the right lowerextremities, general weakness, ataxia, and dysarthria. The initial brain CT showedsubtle ill-defined low-density lesions in the pons and medulla. On brain MRI, T2high signal intensity (T2-HSI) lesions with mild swelling were present in the pons,both middle cerebellar peduncles, and the anterior medulla. The initial diagnosiswas viral encephalitis involving the rhombencephalon. Curiously, a cerebrospinalfluid (CSF) study revealed no cellularity, and negative viral marker findings. Threeweeks later, follow up brain MRI showed that the extent of the T2-HSI lesions in thebrain stem had decreased. After reinvestigation, it was found that she had a priorhistory of upper respiratory infection. In this case, we report the very rare case of apatient showing isolated involvement of the rhombencephalon in ADEM, mimickingviral rhombencephalitis on CT and MR imaging. ADEM can involve unusual sitessuch as the rhombencephalon in isolation, without involvement of the white matteror deep gray matter and, therefore, should be considered even when it appears inunusual anatomical areas. Thorough history taking is important for making a correctdiagnosis.