1. ASNR 2015 Isolated Cerebellar Leptomeningeal Involvement
as an Atypical Radiological Presentation of
Herpes Simplex Virus Infection
B Zeydan1, E Ure2, M Asik3, A Elmali1, S Saip1, Z Hasiloglu2
1Istanbul University, Cerrahpasa School of Medicine, Department of Neurology, Istanbul, Turkey
2Istanbul University, Cerrahpasa School of Medicine, Department of Radiology, Istanbul, Turkey
3Istanbul Medeniyet University, Department of Radiology, Istanbul, Turkey
Presentation number: EP-28
Submission number:1441

2. Disclosure
No Disclosures

3. Background
Herpes simplex virus 1 is one of the most common causative agents of sporadic viral encephalitis.
Clinical features of Herpes simplex virus-1 encephalitis (HSV1-E) involve fever, headache, behavioral abnormalities, seizures and focal neurologic deficits, especially difficulty in word finding (Karen 2014).

4. Purpose
We aimed to present a case with a subacute neurological disease and atypical radiological features consisting of isolated cerebellar leptomeningeal involvement where herpes simplex virus-1 (HSV1) was detected as the etiological agent.

5. Materials & Methods
Twenty-nine year-old female patient was admitted due to speech and walking difficulties.
She had a history of balance problems and progressive speech deterioration.

6. Materials & Methods
She was awake and oriented, could carry out complex cognitive tasks, but was agitated. Meningeal irritation signs were not present.
Her muscle strength was normal, deep tendon reflexes were brisk and Babinski's sign was positive on the left side.
She had bilateral dysmetria, ataxia and dysarthria, which supported cerebellar involvement.

7. Results
Cranial computer tomography and diffusion-weighted magnetic resonance imaging (DWI-MRI) were normal.
Cranial gadolinium-MRI revealed global leptomeningeal contrast enhancement of cerebellar folia, but the cerebral neural parenchyma, especially lateral and inferior temporal lobes characteristic for HSV- 1 encephalitis (HSV1-E) were spared.

8. Results
All parameters of cerebrospinal fluid (CSF) were normal with one exception, positivity for HSV1-PCR.
Her condition started to improve within days with acyclovir treatment. Neuroimaging showed marked regression of cerebellar leptomeningeal contrast enhancement.
HSV1-PCR became negative and HSV1-IgG was positive in recurrent CSF examination.

9. Magnetic Resonance Imaging Findings
Figure 1
Figure 2
Cranial MRI revealed isolated leptomeningeal contrast enhancement of cerebellar folia, on axial (Fig 1) and coronal (Fig 2) T1 plane with gadolinium.

10. Magnetic Resonance Imaging Findings
Figure 3
Figure 4
Cranial MRI showed regression of cerebellar leptomeningeal contrast enhancement under antiviral treatment, on axial (Fig 3) and coronal (Fig 4) T1 plane with gadolinium.

11. Conclusion
Clinical features of HSV1-E involve fever, headache, behavioral abnormalities, seizures and neurologic deficits. The characteristic localization of HSV1-E is temporal lobe and insula.
Fluid attenuated inversion recovery (FLAIR), DWI and T2-weighted images of MRI mostly reveal hyperintense lesions in temporal lobes.

12. Conclusion
Although temporal lobe involvement is suggestive of herpes encephalitis in a patient with encephalitis signs and periodic lateralized epileptiform discharges on electroencephalogram, characteristics of the disease were not detected in our case and especially the cranial MRI was atypical.
But CSF HSV1-PCR positivity, and dramatic response to antiviral treatment supported our diagnosis.
So, HSV1 may be a very rare, but possible etiologic agent in isolated cerebellar leptomeningeal involvement.

13. References
1. Karen L. Roos. Encephalitis. In: Jose Biller and Jose M. Ferro, eds. Handbook of Clinical Neurology, Vol. 121 (3rd series) Neurologic Aspects of Systemic Disease Part III. 1st ed. Elsevier; p
2. Hassan H, Thomas B, Iyer RS. Insights from a rare clinical presentation of herpes simplex encephalitis: adding to the catatonic dilemma? Neurologist 2011:17:114-6.