Operative posterior disconnection in epilepsy surgery: Experience with 29 patients

Abstract

Objective It has been suggested that multilobar epilepsies caused by lesions restricted to the posterior cerebral quadrant (ie, the parietal, temporal, and occipital lobes) can be treated successfully by a procedure termed posterior disconnection. The objective of the present paper was to identify determinants of the epileptological outcome following posterior disconnection surgery. Methods The authors retrospectively analyzed a series of 29 consecutive patients undergoing posterior disconnection surgery between 2005 and 2017 for the treatment of refractory posterior quadrantic epilepsy. Specifically, all presurgical and postoperative magnetic resonance (MR) studies were reviewed to identify cases with an incomplete disconnection, or the presence of a more widespread pathology involving the whole hemisphere rather than only its posterior quadrant. In addition, we reevaluated all presurgical video–electroencephalography (EEG) reports. Results Seizure‐free (International League Against Epilepsy [ILAE] 1) after surgery were 3/3 patients with EEG findings restricted to the posterior quadrant, 0/7 patients who had propagation of epileptic activity to the contralateral frontal lobe, and 11/19 (57.9%) who showed propagation to ipsilateral frontal and/or contralateral posterior. Eleven of 13 (84.6%) patients with purely posterior quadrantic magnetic resonance imaging (MRI) findings (as retrospectively diagnosed by neuroimaging) vs 3/16 (18.8%) cases with additional subtle abnormalities outside the posterior quadrant became seizure‐free (P = .001). Eleven of 16 (68.8%) patients with complete disconnections were seizure‐free vs only 3/13 (23.0%) cases with leftover temporal lobe tissue with contact to the insula (P = .025, both Fisher's exact test). Significance A posterior disconnection is a technically demanding but very effective operation for posterior quadrantic epilepsy. Good epileptologic outcomes require not only that the epileptogenic lesion does not extend beyond the confines of the disconnected cerebral volume but also the absence of subtle MRI abnormalities, more widespread than the clear‐cut lesion of the posterior quadrant. Hemispheric or contralateral (particularly frontal) propagation of the epileptic activity may also indicate the presence of a hemispheric rather than posterior quadrantic pathology.

Posterior Quadrant Disconnection for Childhood Onset Sub-Hemispheric Posterior Head Region Epilepsy: Indications in an Indian Cohort and Outcome

“…At the later stages of the procedure, while performing the medial temporo-pareito-occipital disconnection, neuronavigation helps orient the disconnection in relation to falx as the location of falx does not change much with the brain shift. Kalbhenn et al [7] utilized cortical motor-evoked potential monitoring and a combined mapping and suction device for continuous subcortical direct stimulation to identify the motor pathways during surgery. It is imperative to utilize these adjuncts, so that the risk of hemiplegia is minimized following PQD.…”

“…However, very few studies have reported on the outcomes of posterior quadrant disconnection (PQD), a procedure utilized in conditions where the seizure focus is identified in the posterior head region. Kalbhenn et al [7] commented in 2019 that the literature contained only 6 reports describing ≥10 patients who underwent posterior disconnection surgery.…”

Neurochirurgische Operationsmöglichkeiten bei posteriorer Epilepsie

“…Wurden früher für hauptsächlich große TPO-Mehrlappen Resektionen durchgeführt [14], haben sich in den letzten Jahren minimal-invasive Diskonnektionen durchgesetzt [15][16][17][18] Diese Entwicklung ist mit der Umstellung der Hemisphärektomie (Entfernung der Hemisphäre bis auf die Stammganglien) in Richtung Hemisphärotomie (nur Diskonnektion der Hemisphäre) bei Hemisphärenpathologien mit therapierefraktärer multifokaler unilateraler Epilepsie vergleichbar [19,20].…”

“…Diese gute Erfolgsrate konnte in einer retrospektiven Serie aus dem Klinikum Bethel (Kalbhenn et al 2019) an Patienten mit reiner TPO-Epilepsie bestätigt werden (84,6 % ILAE 1-Outcome) [16]. Dabei handelte es sich auch größtenteils um Kinder.…”

Frontal disconnection surgery for drug‐resistant epilepsy: Outcome in a series of 16 patients

“…Current disconnection surgeries for DRE include functional hemispheric disconnection, corpus callosotomy, temporal disconnection, and posterior quadrant disconnection. Posterior quadrant disconnection was reported in few clinical series 10,14‐20 . We have come across only two surgical series in the literature involving temporal disconnection 11,21 .…”