Abnormal Magnetic Resonance Imaging Findings in a Case of Acute Disseminated Encephalomyelitis
Objective:
To report a case of acute disseminated encephalomyelitis (ADEM) with non-classic MRI findings, diagnosed by autopsy.
Background:
ADEM is an immune-mediated demyelinating disorder of the central nervous system characterized by encephalopathy and polyfocal neurologic deficits. Typical MRI findings include multifocal areas of increased signal intensity on FLAIR/T2-weighted images with extensive perifocal edema and contrast enhancement.
Design/Methods:
Case report.
Results:
This is a 34-year-old female who presented with encephalopathy following one week of headaches, generalized weakness, malaise, fever, and vomiting. On initial examination, patient was disoriented, had minimal verbal output and had poor concentration. Two days after admission, she became plegic in her lower extremities. MRI of the brain revealed multiple small ill-definedT2/FLAIR-hyperintense and T1-hypointense lesions scattered throughout the subcortical white matter, splenium, cerebellar hemispheres and brainstem. These lesions demonstrated restricted diffusion and did not enhance. These findings were most consistent with multiple acute infarctions and patient was treated for shower emboli versus infectious/inflammatory vasculitis with anti-platelets. Despite treatment, patient rapidly deteriorated over the course of a week and lost brainstem reflexes. Repeat MRI demonstrated an increase in the number of acute embolic type infarcts in the cerebral hemispheres, cerebellum and deep gray and white matter structures without associated hemorrhage or enhancement. The extent of brain injury was deemed non-survivable and patient was terminally extubated. Autopsy revealed an acute macrophage-mediated multifocal demyelinating process, consistent with ADEM.
Conclusions:
This patient had imaging findings that were atypical of ADEM, including T1-hypointensities, involvement of the corpus callosum, diffusion restriction and lack of enhancement. Literature review revealed that diffusion restriction may occur in the acute phase; lesions may not enhance as areas of demyelination may evolve over weeks; and lesions can involve the supra- and infratentorial white matter as well as grey matter structures. A familiarity with atypical imaging in ADEM may lend to earlier diagnosis and treatment.