Arterial spin labeling perfusion imaging demonstrates cerebral hyperperfusion in anti-NMDAR encephalitis

Abstract

Anti-N-methyl-d-aspartate receptor encephalitis is an increasingly recognized autoimmune disorder that results in substantial morbidity, prolonged hospital stays, and even death. The diagnosis is often delayed or unrecognized entirely as a result of absent or only subtle initial magnetic resonance imaging findings and a nonspecific clinical syndrome. The discovery of early imaging findings in this disease may help clinicians to more aggressively treat this autoimmune encephalitis and to potentially lessen morbidity and mortality. We report a novel case of anti-N-methyl-d-aspartate receptor encephalitis characterized by early evidence of increased cerebral perfusion on arterial spin labeling perfusion imaging, a finding that preceded laboratory diagnosis and conventional magnetic resonance imaging abnormalities. Further investigation is needed to firmly establish the pathologic basis of this finding.

Keywords: ASL perfusion; Anti-NMDAR encephalitis; MRI.

Fig. 1

Initial brain magnetic resonance imaging arterial spin labeling perfusion images. Focally increased CBF is seen in the right temporoparietal region (red arrows). There is also apparent increased CBF in the paramedian right frontal lobe, but to a lesser extent (blue arrows). CBF, cerebral blood flow; GM, gray matter; WM, white matter.

Fig. 2

First follow-up brain magnetic resonance imaging arterial spin labeling perfusion study obtained on hospital day 10. Diffusely increased CBF is now present in both cerebral hemispheres and involves the bilateral basal ganglia. CBF, cerebral blood flow; GM, gray matter; WM, white matter.

Fig. 3

Magnetic resonance imaging findings on hospital day 38. Diffusion weighted imaging (left) demonstrates restricted diffusion (confirmed on apparent diffusion coefficient map—not shown) in the caudate nuclei, in the right putamen, and in the bilateral posterior thalami (the red arrows suggest cytotoxic edema). Coronal T2-weighted-fluid-attenuated inversion recovery (upper right) and axial T2-weighted imaging (bottom right) show high signal in the bilateral basal ganglia and in the thalami caused by edema.

Fig. 4

Arterial spin labeling perfusion imaging on hospital day 38. Persistent and diffuse markedly increased cerebral cortical blood flow is noted throughout the brain, worsened from the prior examination. CBF, cerebral blood flow; GM, gray matter; WM, white matter.