The supplementary motor area syndrome: a neurosurgical review.

The supplementary motor area (SMA) syndrome is a frequently encountered clinical phenomenon associated with surgery of the dorsomedial prefrontal lobe. The region has a known motor sequencing function and the dominant pre-SMA specifically is associated with more complex language functions; the SMA is furthermore incorporated in the negative motor network. The SMA has a rich interconnectivity with other cortical regions and subcortical structures using the frontal aslant tract (FAT) and the frontostriatal tract (FST). The development of the SMA syndrome is positively correlated with the extent of resection of the SMA region, especially its medial side. This may be due to interruption of the nearby callosal association fibres as the contralateral SMA has a particular important function in brain plasticity after SMA surgery. The syndrome is characterized by a profound decrease in interhemispheric connectivity of the motor network hubs. Clinical improvement is related to increasing connectivity between the contralateral SMA region and the ipsilateral motor hubs. Overall, most patients know a full recovery of the SMA syndrome, however a minority of patients might continue to suffer from mild motor and speech dysfunction. Rarely, no recovery of neurological function after SMA region resection is reported.

Preoperative fMRI in tumour surgery.

Minimally invasive resection of brain tumours aims at removing as much pathological tissue as possible while preserving essential brain functions. Therefore, the precise spatial relationship between the lesion and adjacent functionally essential brain parenchyma needs to be known. Functional magnetic resonance imaging (fMRI) is increasingly being used for this purpose because of its non-invasiveness, its relatively high spatial resolution and the preoperative availability of the results. In this review, the goals of fMRI at various key points during the management of patients with a brain tumour are discussed. Further, several practical aspects associated with fMRI for motor and language functioning are summarised, and the validation of the fMRI results with standard invasive mapping techniques is addressed. Next, several important pitfalls and limitations that warrant careful interpretations of the fMRI results are highlighted. Finally, two important future perspectives of presurgical fMRI are emphasised.