Introduction: Previous studies suggest a correlation of interhemispheric sensorimotor networks with recovery from supplementary motor area (SMA) syndrome. In the present study, we examined the hypothesis that interhemispheric connectivity of the primary motor cortex in one hemisphere with the contralateral SMA may be important in the recovery from SMA syndrome. Further, we hypothesized that motor cortical fiber connectivity with the SMA is related to the severity of SMA syndrome.
Methods: We recruited 11 patients with tumors involving the unilateral SMA region, without involvement of the primary motor area retrospectively. Pre-operative diffusion tensor imaging tractography (DTT) was used to examine the fiber tracts (NFidx) connecting the contralateral SMA area with the ipsilateral primary motor area via the corpus callosum. Complete neurological examination was performed for all patients in the pre- and post-operative periods. All patients were divided 2 groups: those that recovered from SMA syndrome within 7 days (early recovery group), and those recovered in more than 8 days (late recovery group). Differences between the 2 groups were assessed using the Student t test and the chi-squared test.
Results: All patients showed transient post-operative motor deficits because of SMA syndrome. Tractography data revealed NFidx from the contralateral SMA area to the ipsilateral primary motor area via the corpus callosum. The mean tumor volume (Early 27.87 versus Late 50.91; p = 0.028) and mean NFidx (Early 8923.16 versus Late 4726.4; p = 0.002) were significantly different between the 2 groups. Fisher’s exact test showed a significant difference in days of recovery from SMA syndrome between patients with an NFidx >8000 and those with NFidx <8000.
Conclusions: DTT may be useful for predicting the speed of recovery from SMA syndrome. To our knowledge, this is the first DTT study to identify interhemispheric connectivity of SMA in patients with brain tumors.
Patient Care: Predicting of recovery from SMA contributes to the better quality of postoperative rehabilitation and the better counseling how will postoperative neurological deficit go.
Learning Objectives: These findings will be useful for future prediction of recovery from SMA syndrome, and suggest a relationship between cortical fiber connections of the SMA and the degree of deficit in SMA syndrome.