Objective: Multiple subpial transection (MST) is a surgical technique mainly used when epileptiform activity arises from eloquent or functional brain cortex. In the medical literature, there are relatively few studies reporting the efficacy and safety of this procedure in adults and in children. We review the scientific rationale, the indications, and the results of this procedure.
Methods: Neuroanatomic studies show that the basic functional cortical unit is arranged vertically, and epileptic activity spreads horizontally. Minimal cortical unit is essential for maintenance of cortical activity. Vertical incisions in the cortex interrupt transverse synaptic connections, preventing seizure propagation while preserving the vertical column subserving neuronal function. In the past, it has been difficult to assess the efficacy of MSTs per se, as they have usually been performed together with cortical resection or lesionectomy. After MSTs, studies show that 33-46% of treated children are in Engel class I or II. The permanent complication rate is low with no permanent language or motor disabilities.
Conclusions: MST is a safe procedure with unclear specific efficacy. It has been used mainly in conjunction with cortical resection or lesionectomy, when the eloquent cortex is involved in the seizure activity. Further prospective studies are needed to define the role of MST in epilepsy surgery.