5.3.10\ Corticectomy

5.3.10.1\ Discussion

Corticectomy is performed to eliminate seizure foci and consists of resecting the neocortex in the region of an epileptogenic focus with sparring of the underlying white matter. The result can be appreciated on imaging, in which the bare white matter is surrounded by cerebrospinal fluid (Fig. 5.51).

Incomplete excision is the main predictor of poor surgical outcome, and reoperation may be appropriate for selected patients with intractable partial epilepsy who fail to respond to initial surgery. Comparison with the preoperative imaging is helpful, since the residual foci of cortical dysplasia can be subtle. Functional MRI and highresolution sequences are particularly useful in planning additional surgery, since the eloquent areas can be delineated (Fig. 5.52).

a

b

Fig. 5.52  Residual lesions after corticectomy. The patient is a right-handed white male with a long-standing history of intractable epilepsy secondary to a cortical dysplasia in the superior frontal region. Preoperative fMRI (a) shows a left frontal lobe cortical dysplasia (arrow).

Postoperative fMRI (b) obtained after lesionectomy for excision of the epileptogenic focus shows small foci of residual cortical dysplasia (arrows) adjacent to the surgical cavity. However, the eloquent zones (colored areas) have been preserved

5.3.11\ Selective Epilepsy

Disconnection Surgery

and Quadrantectomy

5.3.11.1\ Discussion

The propagation of seizures associated with a diffusely abnormal quadrant of the brain can be impeded by selective disconnection of the underlying white matter tracts, as opposed to resection

a

of entire regions of brain. Depending on the nature of the seizure focus, this can be accomplished via minimally invasive thermal ablation procedures for disrupting very focal white matter tracts (Fig. 5.53) or quadrantectomy for transecting wider areas of tissue, such as temporoparietooccipital disconnection for motor-sparing epilepsy surgery (Fig. 5.54). The disconnection foci or tracts can be readily depicted on postoperative MRI, if needed.

b

Fig. 5.53  Selective frontal lobe disconnection via radiofrequency ablation. Axial inversion recovery T1-weighted (a) and T2-weighted (b) MR images show the lesions

(encircled) created in the right forceps minor in a patient with intractable epilepsy related to Sturge-Weber syndrome with a diffusely atrophic anterior right frontal lobe