We studied 26 patients with a single supratentorial infarction using 99mTc-HMPAO SPECT and MRI to investigate the phenomenon of crossed-cerebellar diaschisis (CCD).
Methods: From the total single-photon emission counts obtained from each cerebellar hemisphere, the percent difference between the contralateral (CCH) and ipsilateral (ICH) cerebellar hemispheres [delta %cbll = (CCH-ICH)/ ICH x 100] was calculated. Both SPECT (SVD) and MRI volume deficit (MVD) were measured to examine their relationship with CCD.
Results: A CCD was observed in 12 of the 26 patients (46%) with cerebral infarction. There was no significant correlation between SVD and delta %cbll or MVD and delta %cbll in the patients with cerebral infarction. There were no significant differences in SVD and MVD between the patients with and without CCD. The frequency of CCD was significantly higher in the patients whose infarctions were in the frontoparietal lobes or the deep middle cerebral artery territory, including the basal ganglia and internal capsule (11/19) than in the patients whose infarctions were in other regions (1/7) (p = 0.048). The severely hemiparetic patients had a higher frequency of CCD and lower delta %cbll than the patients with milder or no hemiparesis (frequency, 5/5 compared with 6/18, p = 0.008; delta %cbll, -21.4% +/- 3.8% compared with -8.3% +/- 11.1%, p = 0.018). However, CCD also occurred in 5 of the 14 patients without hemiparesis and was not seen in 5 of the 12 hemiparetic patients. None of the patients with CCD demonstrated the apparent clinical signs of cerebellar dysfunction.
Conclusion: The location rather than the extent and severity of the lesion may be the major determinant for the occurrence and magnitude of CCD in patients with cerebral infarction. Our results also support the notion that CCD is a consequence of the interruption of the corticopontocerebellar pathway at the supratentorial level.