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MRI and diffusion MRI in nonparaneoplastic limbic encephalitis
1Department of Radiology, Ege University Hospital, 35100 Bornova, Izmir, Turkey. rnsener@hotmail.com
Abstract:
This paper reports an 65-year-old woman with nonparaneoplastic limbic encephalitis. On MRI and diffusion MRI, diffuse and symmetrical, bilateral high-signal lesions were evident in the medial temporal lobes. The affected areas were hyperintense on b= 1000 s/mm(2) (heavily diffusion-weighted or true diffusion) images, a pattern similar to cytotoxic edema. However, apparent diffusion coefficient (ADC) values read directly from corresponding ADC maps at each temporal lobe were within normal limits: 0.96 and 0.97 x 10 x (-3) mm(2)/s, respectively, excluding cytotoxic edema. The changes were shown to be resolved on a 9-month follow-up MRI.
Insights
This study details a case of nonparaneoplastic limbic encephalitis in a 65-year-old woman. Despite MRI findings mimicking cytotoxic edema in the medial temporal lobes, normal apparent diffusion coefficient values excluded this diagnosis, with lesions resolving over time.
Area of Science:
- Neurology
- Radiology
- Neuroimaging
Background:
- Nonparaneoplastic limbic encephalitis is a rare autoimmune disorder affecting the medial temporal lobes.
- Distinguishing limbic encephalitis from other conditions with similar imaging findings is crucial for accurate diagnosis and treatment.
Observation:
- A 65-year-old woman presented with symptoms suggestive of limbic encephalitis.
- Magnetic resonance imaging (MRI) revealed diffuse, symmetrical, bilateral high-signal lesions in the medial temporal lobes.
- These lesions were hyperintense on heavily diffusion-weighted imaging (b=1000 s/mm²), mimicking cytotoxic edema.
Findings:
- Apparent diffusion coefficient (ADC) values in the affected temporal lobes were within normal limits (0.96 and 0.97 x 10⁻³ mm²/s).
- Normal ADC values excluded cytotoxic edema as the cause of the observed MRI signal changes.
- Follow-up MRI at 9 months demonstrated complete resolution of the medial temporal lobe lesions.
Implications:
- This case highlights the importance of integrating diffusion-weighted imaging (DWI) and ADC values for accurate interpretation of medial temporal lobe lesions.
- The findings suggest that nonparaneoplastic limbic encephalitis can present with DWI hyperintensity without true cytotoxic edema.
- Understanding these imaging nuances aids in differentiating limbic encephalitis from conditions like stroke or infection, guiding appropriate clinical management.