Cerebral glucose metabolism basis of prognostic differences between paraneoplastic and non-paraneoplastic anti-GABABR
Guangjuan Mao1, Binbin Nie1, Tianhao Zhang1
1Beijing Engineering Research Center of Radiographic Techniques and Equipment, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China; School of Nuclear Science and Technology, University of Chinese Academy of Sciences, Beijing 100049, China.
Background:
Approximately 50%-60% of anti-gamma-aminobutyric acid B receptor (anti-GABABR) encephalitis are associated with malignancy. Paraneoplastic anti-GABABR encephalitis patients have poorer prognosis than non-paraneoplastic cases. This study aimed to explore distinct cerebral metabolism patterns and network topologies that may underlie prognostic differences in paraneoplastic and non-paraneoplastic anti-GABABR encephalitis, using 18F-fluorodeoxyglucose positron emission tomography (18F-FDG PET) imaging.
Methods:
We retrospectively analyzed FDG PET images from 20 healthy controls, and 20 anti-GABABR encephalitis patients, including 7 patients with malignancy (paraneoplastic subgroup) and 13 patients without malignancy (non-paraneoplastic subgroup). Prognosis outcomes were assessed by comparing modified Rankin Scale scores at hospitalization and discharge between two patient subgroups. We employed voxel-wise statistical parametric mapping to identify cerebral metabolism patterns in each patient subgroup compared with controls. Graph theory analysis was utilized to evaluate topological parameters of metabolism network.
Results:
The non-paraneoplastic subgroup showed significantly greater prognosis outcomes than the paraneoplastic subgroup. Both patient subgroups exhibited a similar hypermetabolism pattern in limbic system. However, paraneoplastic subgroup demonstrated more extensive hypometabolism across parieto-occipital regions. Furthermore, Paraneoplastic subgroup exhibited significantly higher assortativity than non-paraneoplastic subgroup and healthy controls, whereas no such difference was observed between non-paraneoplastic subgroup and controls.
Conclusion:
Compared with non-paraneoplastic subgroup, paraneoplastic subgroup exhibited more widespread hypometabolism patterns, and disruption of metabolic network stability measured by higher assortativity. These distinct metabolic characteristics may underlie prognosis differences in paraneoplastic and non-paraneoplastic cases. These findings may inform more effective treatment strategies, thereby improving the clinical management of anti-GABABR encephalitis.
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