55 years old hypertensive female patient with mild fever, focal seizures, headache, delirium, and disturbed level of conciousness.
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- Left anterior and mesial temporal cortical and subcortical as well as left insular and peri-sylvian area of T1 hypo intensity & T2/FLAIR hyperintensity. The lesion is characteristically sparing the left putamen. The lesion shows cytotoxic brain edema with compression of the left lateral ventricle's temporal horn and effacement of the related cortical sulci.
- A small right mesial temporal focus of hyperintense T2/FALIR signal is noted as well.
- Multiple bilateral deep white matter corona radiata and centrum semiovale demyelinating foci with high T2/FLAIR signal are seen; indicative of chronic small vessel disease.
The above described radiological findings are impressive of Herpes simplex encephalitis. The mortality from HSV is high, so commencement of treatment with antiviral drugs (acyclovir) is recommended without delay with the typical radiological findings in the right clinical settings. Moreover, Herpes simplex encephalitis presenting with normal CSF analysis is reported!
The main diiferential diagnosis is:
- MCA infarct: usually involves the basal ganglia (PUTAMEN).
- Limbic encephalitis: paraneoplastic syndrome with non-CNS 1ry malignant tumor; classically small cell carcinoma of the lung. HSV encephalitis in a cancer patient is a big dilemma!
- Gliomatosis cerebri: ill-defined T2 hyerintense lesion involving two or more lobes of the brain with diffuse enlargement of the affected brain. Minimal mass effect and enhancement. Clinical symptoms are usually diconcordant with the radiological manifestations with usually little symptoms. MR spectroscopy may be a problem solving in some cases.
- 1- Hatipoglu HG, Sakman B, Yuksel E. Magnetic resonance and diffusion-weighted imaging findings of herpes simplex encephalitis. Herpes. 2009;15 (1): 13-7. Pubmed citation
- 2- Jiang Y, Tang L, Gao P et-al. Delayed MRI findings in Herpes simplex encephalitis. Can J Neurol Sci. 2011;38 (1): 155-7. Pubmed citation
- 3- Shian WJ, Chi CS. Magnetic resonance imaging of herpes simplex encephalitis. Zhonghua Min Guo Xiao Er Ke Yi Xue Hui Za Zhi. 1996;37 (1): 22-6. Pubmed citation