Investig Magn Reson Imaging.  2015 Sep;19(3):186-190. 10.13104/imri.2015.19.3.186.

Acute Disseminated Encephalomyelitis Presenting as Rhombencephalitis: An Atypical Case Presentation

• Hwang J
• Lee AL
• Chang KH
• Hong HS

• KMID: 2175614
• DOI: http://doi.org/10.13104/imri.2015.19.3.186

Abstract

Acute disseminated encephalomyelitis (ADEM) is a demyelinating and inflammatory condition of the central nervous system, occurring predominantly in white matter. ADEM involving the rhombencephalon without affecting the white matter is very rare. Here, we present an unusual case of ADEM involving only the rhombencephalon in a 4-year-old Asian girl. The patient complained of pain in the right lower extremities, general weakness, ataxia, and dysarthria. The initial brain CT showed subtle ill-defined low-density lesions in the pons and medulla. On brain MRI, T2 high signal intensity (T2-HSI) lesions with mild swelling were present in the pons, both middle cerebellar peduncles, and the anterior medulla. The initial diagnosis was viral encephalitis involving the rhombencephalon. Curiously, a cerebrospinal fluid (CSF) study revealed no cellularity, and negative viral marker findings. Three weeks later, follow up brain MRI showed that the extent of the T2-HSI lesions in the brain stem had decreased. After reinvestigation, it was found that she had a prior history of upper respiratory infection. In this case, we report the very rare case of a patient showing isolated involvement of the rhombencephalon in ADEM, mimicking viral rhombencephalitis on CT and MR imaging. ADEM can involve unusual sites such as the rhombencephalon in isolation, without involvement of the white matter or deep gray matter and, therefore, should be considered even when it appears in unusual anatomical areas. Thorough history taking is important for making a correct diagnosis.

Keyword

Encephalomyelitis; Acute disseminated; Rhombencephalon; Tomography; X-ray computed; Magnetic resonance imaging

MeSH Terms

Asian Continental Ancestry Group
Ataxia
Biomarkers
Brain
Brain Stem
Central Nervous System
Cerebrospinal Fluid
Child, Preschool
Diagnosis
Dysarthria
Encephalitis, Viral
Encephalomyelitis
Encephalomyelitis, Acute Disseminated*
Female
Follow-Up Studies
Humans
Lower Extremity
Magnetic Resonance Imaging
Pons
Rhombencephalon

Figure

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  Fig. 1 Non-enhanced brain CT axial images (a, b) showing equivocal, ill-defined low-density lesions in the pons and medulla.

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  Fig. 2 Imaging findings of the lesion on brain MRI. (a-c) Axial T2WI showing ill-defined high signal intensity (HSI) with parenchymal swelling in the pons, both middle cerebellar peduncles (arrows), and anterior medulla. (d) Diffusion-weighted imaging showed no diffusion restriction at the sites of the T2-HSI lesions. (e) No definite lesion enhancement is seen on the MR image.

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  Fig. 3 Follow-up MRI scans at 40 days after the onset of clinical symptoms. (a-c) Axial T2-weighted images showing decreased number and extent of T2-HSI in the pons, both middle cerebellar peduncles (arrows), and the medulla.

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