Two cases of SMA syndrome after neurosurgical injury to the frontal aslant tract

Supplementary motor area (SMA) syndrome is characterised by transient disturbance in volitional movement and speech production which classically occurs after injury to the medial premotor area. We present two cases of SMA syndrome following isolated surgical injury to the frontal aslant tract (FAT) with the SMA intact. The first case occurred after resection of a left frontal operculum tumour. The second case occurred after a transcortical approach to a ventricular neurocytoma. The clinical picture and fMRI activation patterns during recovery were typical for SMA syndrome and support the theory that the FAT is a critical bundle in the SMA complex function. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00701-022-05466-6.