Korean J Radiol.  2001 Jun;2(2):68-74. 10.3348/kjr.2001.2.2.68.

Unusual Acute Encephalitis Involving the Thalamus: Imaging Features

• Kim SS
• Chang KH
• Kim KW
• Han MH
• Park SH
• Nam HW
• Choi KH
• Cho WH

• KMID: 754107
• DOI: http://doi.org/10.3348/kjr.2001.2.2.68

Abstract

OBJECTIVE
To describe the brain CT and MR imaging findings of unusual acute encephalitis involving the thalamus. MATERIALS AND METHODS: We retrospectively reviewed the medical records and CT and/or MR imaging findings of six patients with acute encephalitis involving the thalamus. CT (n=6) and MR imaging (n=6) were performed during the acute and/or convalescent stage of the illness. RESULTS: Brain CT showed brain swelling (n=2), low attenuation of both thalami (n=1) or normal findings (n=3). Initial MR imaging indicated that in all patients the thalamus was involved either bilaterally (n=5) or unilaterally (n=1). Lesions were also present in the midbrain (n=5), medial temporal lobe (n=4), pons (n=3), both hippocampi (n=3) the insular cortex (n=2), medulla (n=2), lateral temporal lobe cortex (n=1), both cingulate gyri (n=1), both basal ganglia (n=1), and the left hemispheric cortex (n=1). CONCLUSION: These CT or MR imaging findings of acute encephalitis of unknown etiology were similar to a combination of those of Japanese encephalitis and herpes simplex encephalitis. In order to document the specific causative agents which lead to the appearance of these imaging features, further investigation is required.

Keyword

Brain, CT; Brain, infection; Brain, MR; Encephalitis; Viruses

MeSH Terms

Acute Disease
Adult
Encephalitis/cerebrospinal fluid/*pathology/*radiography
Female
Human
*Magnetic Resonance Imaging
Male
Retrospective Studies
Thalamus/*pathology/*radiography
*Tomography, X-Ray Computed

Figure

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  Fig. 1 Case 1. A 40-year-old woman who presented with fever, chill and altered mentality. A-D. T2-weighted (A, B) and T1-weighted (C, D) images obtained 8 days after the onset of illness show abnormal hyperintensity and hypointensity in both thalami (large black arrows), the left hippocampus (small black arrow), and the medial area of the left temporal lobe (open white arrow). E-F. Follow-up T2-weighted images obtained 11 days after onset show marked enlargement of both thalamic lesions and the development of new lesions in the right hippocampus (white arrow) and brain stem.

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  Fig. 2 Case 5: A 32-year-old man who presented with fever and disorientation. A. CT obtained 3 days after the onset of illness reveals subtle diffuse brain swelling. B-D. T2-weighted images (B, C) obtained 6 days after onset reveal abnormal hyperintensity in both thalami (large black arrows), the left hippocampus (white arrow) and medial area of the left temporal lobe (small black arrow). Gd-enhanced T1-weighted image (D) shows no abnormal thalamic enhancement but subtle corticovascular enhancement. E-G. Follow-up T2-weighted images obtained 18 days after onset show the enlargement of previous lesions and development of new lesions in both basal ganglia, both insular cortices, both substantia nigra (white solid arrows), the lateral cortex of the left temporal lobe (black arrows), the right hippocampus (white open arrows) and the medial area of the right temporal lobe. H, I. Follow-up T2-weighted images obtained 48 days after onset show decreased size of previous lesions. Periventricular white matter abnormality around both frontal horns and diffuse brain atrophy are noticed.

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