PMC9868960_01
MR brain on hospital day 1 revealed symmetric bilateral globus pallidus lesions that exhibited T1 and T2 rim hyperintensities (A, B) and contrast enhancement (F) engulfing a T1 and T2 hypointense necrotic core (A, B). Subtle diffusion restriction of the corona radiata was also demonstrated (C, D), along with several punctate areas of susceptibility signal loss in the supratentorial white matter indicative of microhemorrhages (E). Repeat imaging on hospital day 20 revealed significant progression in diffusion restriction (I) with ADC correlate (J) now extensively involving the supratentorial white matter. The globus pallidus lesions and microhemorrhages remained largely unchanged (G, H, K, L).
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F1
T1- and T2-weighted imaging (Figures 1A,B,F). There was diffusion restriction in the left corona radiata (Figure 1C), together with diffuse foci of susceptibility loss throughout the supratentorial white matter (Figure 1E). T2-FLAIR hyperintensity (Figure 1I). The globus pallidus lesions and microhemorrhages were unchanged (Figures 1G, H, L, K).
FDG-PET scan on hospital day 16 revealed decreased focal uptake in both globus pallidus, diffuse supratentorial hypometabolism with relatively increased tracer uptake in both anteromedial temporal lobes, including the hippocampal formations, parahippocampal gyrus, and amygdala, findings that have been described in limbic encephalitis (A-C).
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F2
The mild hypermetabolism of both anteromedial temporal lobes suggested possible inflammatory mechanisms (Figure 2), and the patient was accordingly treated with IV methylprednisolone 1 g/day for 7 days and plasmapheresis for seven sessions.
Timeline.
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F3
T2 hyperintensities. The chronicity of events is shown in Figure 3.