Extended resection for seizure control of pure motor strip focal cortical dysplasia during awake craniotomy: illustrative case

Abstract

Background: Focal cortical dysplasias (FCD) represent highly intrinsically epileptogenic lesions that require complete resection for seizure control. Resection of pure motor strip FCD can be challenging. Effective control of postoperative seizures is crucial and extending the boundaries of resection in an eloquent zone remains controversial.

Observations: The authors report a 52-year-old right-handed male with refractory epilepsy. The seizure phenotype was a focal crisis with preserved awareness and a clonic motor onset of right-hemibody. Epilepsy surgery protocol demonstrated a left pure motor strip FCD and a full-awake resective procedure with motor brain mapping was performed. Further resection of surgical boundaries monitoring function along intraoperative motor tasks with no direct electrical stimulation corroborated by intraoperative-neuromonitorization was completed as the final part of the surgery. In the follow-up period of 3-years, the patient has an Engel-IB seizure-control with mild distal lower limb palsy and no gate compromise.

Lessons: This report represents one of the few cases with pure motor strip FCD resection. In a scenario similar to this case, the authors consider that this variation can be useful to improve seizure control and the quality of life of these patients by extending the resection of a more extensive epileptogenic zone minimizing functional damage.

Keywords: awake craniotomy; brain mapping; epilepsy surgery; focal cortical dysplasia.

FIG. 1.

Presurgical neuroimaging findings. A: fMRI, hyperdensity signal in left precentral gyrus corresponding with a FCD (white arrow) adjacent to left hand motor area. B and C: Coronal and sagittal flair-weighted MRI showing a cortical hyperintense image in the bottom of precentral sulcus corresponding to the FCD (white arrow). D: Pyramidal tract (yellow arrow) close to FCD (white arrow). Postsurgical neuroimaging findings. E and F: Sagittal and coronal T1-weighted MRI showing the area of FCD resection (white arrow). G: fMRI 1 year after surgery. FCD resection area (white arrow) adjacent to the left-hand motor region is observed. H and I: Axial diffusion-weighted MRI, 1 year after surgery. No evidence of infarcts adjacent to the FCD resection area (yellow arrows). J and K: Histopathological findings, hematoxylin-eosin staining, showing type II FCD (microscopic heterotopia outside of cortical layer I).

FIG. 2.

A: Ad hoc MTD. MTD was manufactured with acrylic to be compatible with fMRI scans. B and C: Upper limb motor function. MTD was planned to perform a continuum medial rotation-cubital deviation movement of the upper limb that combines the qualitative monitoring of distal and proximal muscles in a short period and allows early detection of subtle motion compromise.