Diaschisis in chronic viral encephalitis with Koshevnikov syndrome

Correlation of Asymmetry Indices Measured by Arterial Spin-Labeling MR Imaging and SPECT in Patients with Crossed Cerebellar Diaschisis

BACKGROUND AND PURPOSE

Crossed cerebellar diaschisis, not only a secondary result of supratentorial infarction but also an indicator of clinical outcomes, has frequently been reported on PET and SPECT but has been rarely described with arterial spin-labeling MR imaging. The purpose of this study was to determine the ability of arterial spin-labeling MR imaging to evaluate crossed cerebellar diaschisis compared with that of SPECT. To our knowledge, this is the first study to validate arterial spin-labeling in crossed cerebellar diaschisis by using SPECT as a reference standard.

MATERIALS AND METHODS

This study included 16 patients in whom crossed cerebellar diaschisis was shown on SPECT and 10 control subjects in whom crossed cerebellar diaschisis was not shown on SPECT. During the qualitative analysis, asymmetric cerebellar perfusion on arterial spin-labeling was divided into 1 of the following 3 grades by 2 blinded observers: the affected cerebellum was isointense compared with the unaffected cerebellum (grade I), it was slightly hypointense (grade II), or it was markedly hypointense (grade III). In the quantitative analysis, asymmetry indices were calculated by using SPECT and arterial spin-labeling images. For statistical analysis, κ statistics, the interobserver correlation coefficient, the independent t test, Pearson correlation, and linear regression analysis were used.

RESULTS

Almost all the diagnoses of crossed cerebellar diaschisis on SPECT were noted on arterial spin-labeling in both qualitative and quantitative analyses with good interobserver agreement (κ = 0.961; interobserver correlation coefficient, 0.806). The mean asymmetry index of arterial spin-labeling (26.06 ± 9.00) was significantly larger than that for SPECT (15.28 ± 5.34; P < .001). There was a significant positive correlation between the asymmetry indices obtained for SPECT and those for arterial spin-labeling (r = 0.77 [95% CI, 0.443-0.916]; P < .001). The relationship of asymmetry indices between SPECT and arterial spin-labeling (x, y) was calculated as y = 6.2131 + 1.2986x (R(2) = 0.592; P < .001).

CONCLUSIONS

Arterial spin-labeling can be a noninvasive alternative to SPECT for evaluating crossed cerebellar diaschisis.

Viral encephalitis: neuropsychiatric and neurobehavioral aspects

Viral encephalitis, a condition in which a virus infects the brain and produces an inflammatory response, affects approximately 20,000 individuals per year in the United States. The viral encephalidities include sporadic and epidemic acute viral encephalidities and subacute and chronic/progressive viral encephalitis or encephalomyelitis. In people who survive these conditions, postencephalitic impairments of elemental neurologic, cognitive, emotional, and behavioral function are common. This article will provide a brief overview of the diagnosis and acute management of acute viral infections of the central nervous system. The neurologic and neuropsychiatric features, neuropathologies, and treatments of two of the more common types of acute viral encephalitis in North America--herpes simplex encephalitis and West Nile encephalitis--will be reviewed. The current and future role of psychiatrists and neuropsychiatrists in the care and study of individuals with these conditions will be discussed.

Crossed cerebellar diaschisis in herpes simplex encephalitis

Diaschisis is extremely rare in patients with viral encephalitis. We report the phenomenon of crossed cerebellar diaschisis (CCD) in a 73-year-old man with acute herpes simplex type-1 (HSV-1) encephalitis. The diagnosis of HSV-1 encephalitis was confirmed by detecting HSV-1 deoxyribonucleic acid in the cerebrospinal fluid (CSF). Magnetic resonance images (MRI) showed enhancing lesions at bilateral temporal lobes, insular cortices, and right frontoparietal lobes. Increase signal intensity on T2-weighted images was seen in the mesecephalon. Technetium-99m ethyl cysteinate dimer (99mTc-ECD) single photon emission computed tomography (SPECT) of the brain showed a large area of hypoperfusion in the right frontotemporoparietal lobes. The side-to-side cerebellar count revealed 19% reduction of the radioisotope tracer uptake in the left cerebellum. The phenomenon of CCD was proposed to be due to both anterograde disconnection of the corticopontocerebellar tracts and retrograde deafferentation of dentatothalamocortical projections.