Crossed Cerebellar Diaschisis: Risk Factors and Prognostic Value in Medically Intractable Epilepsy by 18F-FDG PET/CT
Abstract Purpose Crossed cerebellar diaschisis (CCD) has been widely studied in hemispheric stroke but is less characterized in epilepsy. In this study, we used 18F-FDG positron emission tomography (PET)/computed tomography (CT) to investigate the risk factors for CCD and its prognostic value for intractable epilepsy. Methods One hundred medically intractable epilepsy patients pathologically diagnosed with focal cortical dysplasia (FCD) postoperatively were included and classified into two groups: CCD+ and CCD-. All patients underwent 18F-FDG PET/CT preoperatively. PET/CT images were analysed qualitatively by visual assessment and semi-quantitatively using the absolute asymmetry index (|AI|). Clinical factors, including age, sex, body mass index (BMI), age at seizure onset, epilepsy duration, seizure type, epilepsy severity, electroencephalography(EEG) and brain magnetic resonance imaging (MRI), were retrospectively assessed from medical records. Follow-up outcomes were evaluated according to the Engel classification at 3, 6, 12, 24 and 36 months postoperatively.Results Of the 100 patients, 77 (77%) were classified as CCD-, and 23 (23%) were classified as CCD+. CCD+ patients had a higher number of lobes involved on PET (3.61±2.16 vs 2.26±1.01, P<0.001) and more cases of occipital hypometabolism (21.74% vs 5.19%, P=0.03) than CCD- patients. CCD- patients showed more negative MRI results than CCD+ patients (P=0.02). Patients with a poor prognosis had more cases of parietal hypometabolism on PET (P=0.02). At 12 months postoperatively, 71%(29/41) of CCD- patients and 31%(4/13) of CCD+ patients presented a favourable prognosis (P=0.02). Significant differences in the average |AI| values in the posterior frontal and anterior temporal lobes were found between CCD+ and CCD- patients (P<0.05), but no significant correlation of the |AI| between supratentorial regions and the contralateral cerebellum was identified in CCD+ patients. Conclusion The number of lobes involved on PET, structural anomalies on MRI, the lesion location on PET, the |AI| values in the posterior frontal and anterior temporal lobes may be predisposing factors for CCD. CCD occurrence may help predict the prognosis of FCD patients at 12 months postoperatively, and parietal hypometabolism on PET may indicate a poor prognosis.