Fluorine-18-FDG evaluation of crossed cerebellar diaschisis in head injury

This study investigates the phenomenon of crossed cerebellar diaschisis in head injury patients. Methods: We visually compared fluorine-18-fluorodeoxyglucose (FDG)-PET images to radiograph computed tomography or magnetic resonance images in 19 patients with head injury. Results: We found that of 68 focal unilateral lesions, 40% were associated with contralateral cerebellar hypometabolism and 19% were associated with ipsilateral cerebellar hypometabolism. Of supratentorial, extraparenchymal lesions (n = 20), 45% were associated with contralateral cerebellar hypometabolism, whereas 15% had ipsilateral cerebellar hypometabolism. Intraparenchymal lesions were associated with contralateral cerebellar hypometabolism in 38% of the patients and with ipsilateral cerebellar hypometabolism in 21% of the patients. Of the cortical lesions that were the patients' most severe injury, 69% were associated with contralateral cerebellar hypometabolism, whereas only 8% were associated with ipsilateral cerebellar hypometabolism. In patients with focal supratentorial lesions alone, 50% of all focal lesions were associated with contralateral cerebellar hypometabolism and 13% had ipsilateral hypometabolism. Of patients with both focal and diffuse brain injuries, 27% of the focal lesions had contralateral cerebellar hypometabolism and 27% had ipsilateral cerebellar hypometabolism to the most severe focal injury. Conclusion: Crossed cerebellar diaschisis is seen more often in patients with focal cortical or extraparenchymal injuries and is not seen in patients with multiple or diffuse brain injuries. Furthermore, this predominance is more pronounced with lesions of the greatest severity.