CASE 5324 Published on 20.03.2008
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Acute subarachnoid hemorrhage as presentation of herpes simplex encephalitis

Section

Neuroradiology

Case Type

Clinical Cases

Authors

Canyigit M, Yavuz K, OGUZ KK. Hacettepe University, Faculty of Medicine Department of Radiology Sihhiye 06100, Ankara, Turkey Corresponding author: Oguz KK, Hacettepe University, Department of Radiology, Ankara, Turkey 06100. e-mail: karlioguz@yahoo.com Phone:+90 3123051188 FAX:+90 312 3112145

Connected authors
Patient

8 years, male

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Clinical History
An 8-year-old male patient with 49, XXXXY syndrome was referred to the radiology department as he had two focal seizures in the last 3-days and a 1-week history of headache in left temporal region.
Imaging Findings
An 8-year-old male patient with 49, XXXXY syndrome was seizure-free since he was given a diagnosis of epilepsy and was put on an antiepileptic therapy at age 5. He was referred to the radiology department as he had two focal seizures in the last 3-days and a 1-week history of headache in left temporal region. Fever for one week under antibiotic therapy, weakness were achieved in the history. No significant change was observed in his mental status. Physical examination revealed hypertrophy of the tonsils, hyperemia of the oropharynx, nuchal rigidity and mucocutaneous eruptions at the tip of the nose. Cranial CT and MR imaging with a 3T MR scanner was performed.
Discussion
Cranial CT examination showed acute hemorrhage at left temporal lobe. Associated cortical thickening with hypodensity and sulcal effacement suggestive of edema or ischemia at left temporal lobe were observed (Fig 1). MR imaging showed acute-early subacute hemorrhage in the left medial temporal lobe, left Sylvian fissure and in both lateral ventricles. Cortical swelling and hyperintensity on T2-WI as well as profound meningeal and cortical enhancement predominantly on the left temporal lobe on postcontrast T1-WI was present. Meningeal enhancement was diffuse over the cerebral hemispheres and cortical involvement was extensive in the left cerebral hemisphere including posterior parietal and occipital lobes (Fig 2A, B). DWI revealed mild increased cortical intensity that is attributable to T2-shine through effect. Calculated ADC values were 1.15 x 10-3, 1.03 x 10-3, 0.86 x 10-3 mm2/sn in the left temporal lobe from anterior to posterior and were 0.96 x 10-3, 0.90 x 10-3, 0.86 x 10-3 mm2/sn correspondingly in the contralateral normal appearing parenchyma. Accordingly, anteromedial temporal lobe showed restricted diffusion (0.54 x 10-3 mm2/sn, contralateral 0.91 x 10-3 mm2/sn) resulting from blood both in the parenchyma and subarachnoid space, while other affected areas had increased diffusion consistent with vasogenic edema (Fig 3A, B). Decreased caliber of the left distal ICA shown by MR imaging (Fig 4). An arachnoid cyst in the interpedincular cistern was observed in the patient incidentally (Fig 2A). Hemorrhagic temporal lobe lesions in the appropriate clinical setting is highly suggestive of HSE; however, although consistently present at pathological specimens, hemorrhage is infrequently seen by imaging, especially CT (1). Analysis of CSF obtained from a non-traumatic tap reveals excessive red blood cells (>500/mm3) besides pleocytosis in approximately 20% of patients with acute encephalitis. Typically associated with necrotizing and hemorrhagic encephalitis (2). Apart from necrotizing nature of the disease, possibly accompanying vasculitis as with varicella zoster might have caused SAH. Manifestation of circumferentially symmetrical narrowing of the left distal ICA by MR studies could give a support for infectious vasculitis in this case (3). It is consistently shown that MR imaging is more sensitive than CT for detection of cerebral lesions of HSE (2, 4). HSE in children and adults could be hemorrhagic with initial findings restricted to the medial and inferior temporal lobes. Imaging often displays unilateral findings, with a spread to contralateral side not infrequently. Involved areas appear hypointense on T1-WI and hyperintense on T2-WI on MR imaging unless hemorrhage accompanies (2). Recently, DWI proved to be superior to ‘conventional’ images, providing more information on affected brain tissue, and especially in cases with restricted water molecular motion. Showing the type of the edema (cytotoxic vs. vasogenic) in HSE by calculation of ADC values has been found important as it might have a prognostic value on the clinical outcome (4, 5). In a study by Sener RN, the cases which DWI showed predominantly cytotoxic edema were in severe clinical condition, while others had a better outcome following prompt therapy (4).
Differential Diagnosis List
Herpes Simplex encephalitis
Final Diagnosis
Herpes Simplex encephalitis
Case information
URL: https://www.eurorad.org/case/5324
DOI: 10.1594/EURORAD/CASE.5324
ISSN: 1563-4086
Figure 1

Figure 1

Figure 1
Noncontrast CT scan shows acute temporal sulcal, parenchymal and Sylvian blood and temporal cortical swelling and hypodensity on two consecutive slices.
Figure 2

Figure 2

Figure 2
Axial T2-weighted TSE image demonstrates extensive temporal cortical swelling and hyperintensity as well as acute subarachnoid and parenchymal hemorrhage. Please note layering blood at the dependent region of the lateral ventricle (arrow) and associated arachnoid cyst separating optic tracts (arrowhead).
Figure 2
On postcontrast coronal T1-weighted spin-echo images, left temporoccipital parenchymal (thin arrows) and diffuse meningeal enhancement on both cerebral hemispheres are seen.
Figure 3

Figure 3

Figure 3
On DWI, affected cortices are of increased intensity compared with contralateral parenchyma which is greatly due to T2-shine through effect.
Figure 3
Involved areas have increased ADC values except a small anterior and medial area with acute hemorrhage shown by other imaging techniques.
Figure 4

Figure 4

Figure 4
Coronal T2-weighted TSE image demostrate decreased caliber of the left cavernous internal carotid artery (arrow).