A case with relapsing episodes of weakness and seizures.
During the initial visit, magnetic resonance (MR) images were obtained (Figure 1). Over the course of the next year, the patient presented to the hospital six times for additional symptoms including weakness, slurred speech, and seizures. During this period, brain biopsy, serology tests, and MR spectroscopy were performed confirming the initial diagnosis. Moreover, multiple MR images were performed showing progression and relapsing (Figure 2).
Multiphasic Acute Disseminated Encephalomyelitis (ADEM) IMAGING FINDINGS
Figure 1. MR: axial fluid attenuated inversion recovery (FLAIR) (A), sagittal FLAIR (B), axial T1 (C), and axial T2 (D) images showing large globular lesions in the deep white matter consistent with demyelinating processes seen in ADEM. Figure 2 (A) demonstrates on MR spectroscopy elevated choline peak (arrow) indicating myelin breakdown products, lactate doublet (arrowhead) and myo-inositol peak (asterisk) which can be seen in demyelinating disorders such as ADEM; Axial FLAIR images during relapses at four months (B) and two years (C) after the initial diagnosis of ADEM showing new demyelinating lesions during each relapse. Follow up axial FLAIR image (D) at two years showing partial resolution of previous lesions.
Acute disseminated encephalomyelitis (ADEM) is an inflammatory demyelinating disorder of the central nervous system (CNS) predominantly affecting the white matter of brain and spinal cord. (1) The disease is seen in all age groups, but is more common in pediatric patients with a mean age of presentation ranging from 5-8 years. (1) ADEM is typically monophasic, though relapses have been described in literature occurring at a rate of 5.5-21 percent. The term "multiphasic disseminated encephalomyelitis" (MDEM) can be used to refer to relapses of the same acute monophasic immune process. (1,2) MDEM involves a polysymptomatic presentation and is characterized by new clinical events of ADEM involving new anatomic areas of the CNS at least three months after the onset of the initial presentation of ADEM. Additionally, the diagnosis of MDEM is confirmed by neuroimaging and neurologic examination. (3) The pathogenesis of ADEM/MDEM is unclear, but is associated with reported antecedent viral infection or immunization in 70-77 percent of patients with a mean latency of 13 days (range 2-31 days). (1,2,4)
Clinically, patients typically present with fever, headache, nausea, and meningeal signs. (4) Following hours or days, the symptoms progress to any combination of pyramidal symptoms (60-95%), acute hemiplegia (76%), ataxia (18-65%), cranial nerve palsies (22-45%), visual loss (7-23%), seizures (13-35%), spinal cord signs (24%), impairment of speech (5-21%), and hemiparesthesia (23%). (1,4) The severity of disease can range from irritability, headache, and somnolence, to coma and respiratory failure, with a fatality rate of 10-15 percent.1, (5) Differential diagnosis of ADEM/MDEM includes several inflammatory and non-inflammatory disorders with similar clinical and radiologic presentation. Multiple sclerosis (MS) is highly suspicious in patients with MDEM. (1,3) Other similar entities include neurosarcoidosis, vasculitis, progressive multifocal leukoencephalopathy, gliomatosis cerebri, CNS lymphoma and posterior reversible encephalopathy syndrome. (3) Differentiating ADEM from alternative entities is important due to prognostic and treatment differences. Treatment of ADEM may include corticosteroid therapy, intravenous immunoglobulin G and plasmapheresis. (1,3)
In computed tomography (CT), ADEM patients may have hypodense lesions in the cerebral white matter with iodinated contrast enhancement. These lesions typically increase in severity as the disease progresses. (5) In MR imaging, ADEM brain lesions are large, lobular, and found in deep white matter. These lesions are typically hyperintense in T2-weighted sequences, hypointense in T1-weighted images, and are enhanced with gadolinium. (5) By contrast, MS lesions are usually located in periventricular white matter. (2) Follow-up imaging of ADEM/MDEM patients has shown complete lesion resolution in 37 percent of patients, partial resolution in 53 percent of patients, and no significant change in 10 percent. While new lesions may be seen in both relapsing patients and asymptomatic patients, no complete resolution of previous lesions is seen in relapsing patients. (2)
David Liu, BS; Juan S. Gomez, MD; Enrique Palacios, MD; Jeremy B. Nguyen, MD; and Harold R. Neitzschman, MD, (Section Editor)
(1.) Tenembaum S, Chitnis T, Ness J, et al. Acute disseminated encephalomyelitis. Neurol. 2007;68: 23-36.
(2.) Dale RC, de Soussa C, Chong WK, et al. Acute disseminated encephalomyelitis, multiphasic disseminated encephalomyelitis and multiple sclerosis in children. Brain 2000;123:2407-2422.
(3.) Wingerchuck DM, Weinshenker BG. Acute disseminated encephalomyelitis, transverse Myelitis, and neuromyelitis optica. Am Ac Neurol. 2013;19:944-967.
(4.) Schwarz S, Mohr A, Kanauth M, et al. Acute disseminated encephalomyelitis: a follow-up study of 40 adult patients. Neurol. 2001;56:1313-1318.
(5.) Wender, Mieczyslaw. Acute disseminated encephalomyelitis (ADEM). J Neuroimmunol. 2011; 23:92-99.
(6.) Bizzi, Alberto, et al. Quantitative proton MR spectroscopic imaging in acute disseminated encephalomyelitis. Am J Neuroradiol.2001; 22:1125-1130.
Dr. Gomez is a medical doctor from Bogota, Columbia; Mr. Liu is a medical student at Tulane University Health Sciences Center in New Orleans, LA; Dr. Palacios is a professor of radiology and Dr. Nguyen is an assistant clinical professor of radiology at the Tulane University Health Sciences Center in New Orleans, LA; Dr. Neitzschman is a professor of radiology and the Chairman of the Department of Radiology at the Tulane University Health Sciences Center in New Orleans, LA. Mr. Olivares is the digital imaging specialist and graphic designer for the Department of Radiology at the Tulane University Health Sciences Center in New Orleans, LA.
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|Title Annotation:||Radiology Case of the Month|
|Author:||Liu, David; Gomez, Juan S.; Palacios, Enrique; Nguyen, Jeremy B.; Neitzschman, Harold R.|
|Publication:||The Journal of the Louisiana State Medical Society|
|Article Type:||Clinical report|
|Date:||May 1, 2015|
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