Posterior Quadrant Disconnection Research Articles

Total posterior quadrant disconnection for drug‐resistant epilepsy in children

AbstractObjectiveTo assess seizure outcomes, prognostic factors, and developmental changes in children undergoing total posterior quadrant disconnection (PQD) for drug‐resistant epilepsy (DRE).MethodsWe conducted a retrospective analysis of the clinical data of children with DRE who underwent total PQD surgery. The study focused on Engel's classification for seizure outcomes, exploring correlation of preoperative data and surgical effectiveness, and predictors of seizure prognosis. It involved a comparative analysis of developmental levels pre‐ and 3 months postoperatively using Griffiths Mental Development Scales‐China (GMDS‐C), and the correlation between clinical characteristics and GMDS‐C results.ResultsOut of 61 pediatric patients, 70.5% showed no seizure recurrence postoperatively. In the univariate analysis, interictal electroencephalogram (EEG), magnetic resonance imaging (MRI), fluorodeoxyglucose positron emission tomography (FDG‐PET), and acute postoperative seizure (APOS) were significantly related to surgical prognosis. In multivariate analysis, interictal EEG and APOS were identified as predictors of seizure prognosis. Survival analysis indicated significant associations between MRI, interictal EEG, FDG‐PET, APOS and postoperative seizure occurrence. Preoperative GMDS‐C levels were significantly correlated with epilepsy duration, seizure frequency, interictal EEG, and FDG‐PET. GMDS‐C scores improved postoperatively, while developmental quotients remained stable.SignificanceFor patients with structural abnormalities in the entire posterior quadrant, thorough preoperative assessment and timely total PQD surgery can effectively control seizures without causing neurological development deterioration. APOS and interictal EEG abnormalities beyond the posterior quadrant are predictors for seizure prognosis but should not be deemed contraindications for surgery.Plain Language SummaryDue to lack of analysis on pediatric total PQD cases, 61 pediatric patients who underwent total PQD surgery were retrospectively enrolled. Seizure and development results were collected and analyzed as dependent variables. The study found that 70.5% of patients were seizure‐free and showed development improvement, with no deaths or severe complications reported. Prognosis predictors included APOS and interictal EEG abnormalities beyond the posterior quadrant.

Posterior Quadrant Disconnection Procedure for Intractable Epilepsy: A Case Series of 5 Young Pediatric Patients.

Posterior quadrant disconnection (PQD) has been described as a treatment for patients with refractory posterior quadrant subhemispheric epilepsy. Surgical outcomes are difficult to interpret because of limited literature. To provide insight regarding the operative technique and postsurgical seizure freedom in young pediatric patients who underwent surgical disconnection for the treatment of posterior quadrant subhemispheric epilepsy at our institution. The authors retrospectively analyzed a series of 5 patients who underwent PQD between 2019 and 2021. Charts were reviewed for preoperative workup including noninvasive/invasive testing, operative reports, and postoperative follow-up data which included degree of seizure freedom, completion of disconnection, and complications. Five patients were included in this series. The median age at seizure onset was 12 months (range 3-24 months), and the median age at surgery was 36 months (range 22-72 months). Histopathology confirmed focal cortical dysplasia in 3 of 5 patients (2 patients with type IB; 1 with type IIID). The average length of follow-up after surgery was 16.8 months (range 12-24 months). All patients underwent complete disconnection of the posterior quadrant without complications. Four of 5 patients (80%) had Engel score of I, while the remaining patient had an Engel score of IIB. Our early results demonstrate that complete PQD can be successful at providing excellent seizure freedom and functional outcomes in carefully selected young pediatric patients who have concordant seizure semiology, noninvasive/invasive testing, and imaging findings with primary seizure onset zone within the ipsilateral posterior quadrant. Meticulous surgical planning and thorough understanding of the surgical anatomy and technique are critical to achieving complete disconnection.

Feasibility of Tailored Unilateral Disconnection vs Callosotomy for Refractory Epilepsy in Patients with Bilateral Parieto-Occipital Gliosis Following Perinatal Insult.

Patients with perinatal hypoxia (PH) and drug-refractory epilepsy (DRE) often have bilateral parieto-occipital gliosis. Surgical management of such patients is a dilemma. To identify preoperative determinants for unilateral disconnection vs callosotomy, and analyze the surgical outcome in such patients. This was a retrospective analysis of patients with DRE and history of PH, with MRI abnormalities restricted to bilateral posterior quadrants. Preoperative semiology, epilepsy duration and seizure frequency were recorded. Based on the concordance between the results of non-invasive tests, patients underwent either posterior quadrant disconnection (PQD) or corpus callosotomy (CC). Preoperative variables were analyzed and corelated to the postoperative seizure freedom. Fourteen patients were identified, 6 underwent PQD and 8 underwent CC. At follow up of 39.17 ± 23.75 months, 66.66% of patients (4/6) in the PQD subgroup had an ILAE Class I outcome. While none in the CC group attained seizure freedom, 87.5% (7/8) had more than 50% reduction in seizure frequency (follow up: 42 ± 27.31 months). Patients with a poor outcome had significantly greater seizure frequency (P = 0.05) and history of drop attacks (P = 0.04) in both the groups. Magnetoencephalography (MEG) accurately localized the epileptogenic zone in all of the patients with good outcome (P = 0.015). Concordance with single photon emission tomography (SPECT) was also a predictor of favorable outcome (P = 0.041). A history of drop attacks with high seizure frequency is associated with poor postoperative seizure outcome. Unilateral PQD is feasible and leads to superior seizure-free outcomes, even in cases with widespread and bilateral imaging and electrical abnormalities, provided the other preoperative investigations are concordant in localizing the epileptogenic zone.

Commentary: Completion Posterior Quadrant Disconnection After Failed Temporal Lobectomy: 2-Dimensional Operative Video.

Singh, Rohin BS*; Bendok, Bernard R. MD‡,§,‖; Zimmerman, Richard S. MD‡ Author Information

Completion Posterior Quadrant Disconnection After Failed Temporal Lobectomy: 2-Dimensional Operative Video

Epilepsy is a chronic seizure disorder that affects about 1% of the global population.1 When seizure freedom cannot be obtained solely through antiseizure medicines (ASMs), the condition is termed medically refractory epilepsy (MRE).2,3 Though posterior quadrant disconnection (PQD) is underutilized in our experience, it is a highly effective surgical procedure for MRE restricted to the temporal, parietal, and/or occipital lobes.4-12 In this operative video, we demonstrate a right-sided completion PQD following failed temporal lobectomy in an 8-yr-old female with focal MRE. We review technical nuances, including (1) extension/revision of prior scalp incision, (2) placement of subdural strip for the identification of phase reversal and central sulcus, (3) disconnection of parietal and occipital lobes, (4) extension of the corticectomy to the pia overlying the falcotentorial junction and into the prior temporal lobectomy defect, and (5) posterior disconnection of the corpus callosum. Postoperatively, the patient experienced subtle left-arm weakness and central fever, both of which resolved. An external ventricular drain (EVD) was placed in the ventricle/operative cavity and left for 3 to 4 d until the draining cerebrospinal fluid (CSF) cleared. As of 3-mo follow-up, she has been seizure-free without complications. In summary, PQD is a safe and effective treatment option for MRE that can be utilized not only as an initial operation but also after failed surgery. Appropriate patient consent was obtained to perform this procedure and present this clinical case and surgical video for academic purposes. Image at 4:00 licensed under CC BY-2.5, 2006, modified from http://upload.wikimedia.org/wikipedia/commons/7/70/Lateral_head_skull.jpg (flipped and rotated). Image at 4:42, Public Domain: Gray H. Anatomy of the Human Body. 1918. Bartleby.com, https://commons.wikimedia.org/wiki/File:Lobes_of_the_brain_NL.svg; flipped, modified. Image at 6:42, Public Domain: House EL, Pansky B. A Functional Approach to Neuroanatomy. 1960. McGraw-Hill Book Company; https://upload.wikimedia.wikipedia.commons/5/52/Lawrence_1960_2.3.png; modified.

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

Background: Posterior quadrant disconnection (PQD) is an under-utilized surgical technique in the management of refractory epilepsy. There is a dearth of data pertinent to post-PQD seizure outcomes. Methods: This retrospective study analyzed patients with drug-resistant childhood-onset epilepsy who underwent PQD at our center from 2009 to 2018. The clinical, imaging, and electrophysiological data were reviewed. The seizure outcome was noted from the latest follow-up in all patients. Results: Fifteen patients underwent PQD, with a mean age at onset of epilepsy of 3.3 ± 4.6 years. All patients had seizure onset in childhood with focal onset of seizures, and in addition, 5 had multiple seizure types. All cases underwent presurgical workup with MRI, video-EEG, psychometry, while PET/MEG was done if required. Engel Ia and ILAE I outcomes were considered to be favorable. The histology of the specimen showed 9 patients (60%) had gliosis, 4 (26.7%) had focal cortical dysplasia (FCD), while 1 patient had nodular heterotopia and another had polymicrogyria-pachygyria complex. Postoperative follow-up was available in 14 cases. One patient was lost to follow-up. Mean follow-up duration for the cohort was 45 + 24 months. At last, follow-up (n = 14), 66.7% (10 cases) had favorable outcome (Engel Ia). At the end of 1-year follow-up, up to 73% (n = 11) of the patients were seizure-free. Four patients developed transient hemiparesis after surgery which improved completely by 3–6 months. Conclusions: Gliosis was more common etiology requiring PQD in our series than Western series, where FCD was more common. PQD is a safe and effective surgical modality in childhood-onset epilepsy with posterior head region epileptogenic focus.

Phase-amplitude coupling of interictal fast activities modulated by slow waves on scalp EEG and its correlation with seizure outcomes of disconnection surgery in children with intractable nonlesional epileptic spasms.

Epileptic spasms (ESs) are classified as focal, generalized, or unknown onset ESs. The classification of ESs and surgery in patients without lesions apparent on MRI is challenging. Total corpus callosotomy (TCC) is a surgical option for diagnosis of the lateralization and possible treatment for ESs. This study investigated phase-amplitude coupling (PAC) of fast activity modulated by slow waves on scalp electroencephalography (EEG) to evaluate the strength of the modulation index (MI) before and after disconnection surgery in children with intractable nonlesional ESs. The authors hypothesize that a decreased MI due to surgery correlates with good seizure outcomes. The authors studied 10 children with ESs without lesions on MRI who underwent disconnection surgeries. Scalp EEG was obtained before and after surgery. The authors collected 20 epochs of 3 minutes each during non-rapid eye movement sleep. The MI of the gamma (30-70 Hz) amplitude and delta (0.5-4 Hz) phase was obtained in each electrode. MIs for each electrode were averaged in 4 brain areas (left/right, anterior/posterior quadrants) and evaluated to determine the correlation with seizure outcomes. The median age at first surgery was 2.3 years (range 10 months-9.1 years). Two patients with focal onset ESs underwent anterior quadrant disconnection (AQD). TCC alone was performed in 5 patients with generalized or unknown onset ESs. Two patients achieved seizure freedom. Three patients had residual generalized onset ESs. Disconnection surgeries in addition to TCC consisted of TCC + posterior quadrant disconnection (PQD) (1 patient); TCC + AQD + PQD (1 patient); and TCC + AQD + hemispherotomy (1 patient). Seven patients became seizure free with a mean follow-up period of 28 months (range 5-54 months). After TCC, MIs in 4 quadrants were significantly lower in the 2 seizure-free patients than in the 6 patients with residual ESs (p < 0.001). After all 15 disconnection surgeries in 10 patients, MIs in the 13 target quadrants for each disconnection surgery that resulted in freedom from seizures were significantly lower than in the 26 target quadrants in patients with residual ESs (p < 0.001). In children with nonlesional ESs, PAC for scalp EEG before and after disconnection surgery may be a surrogate marker for control of ESs. The MI may indicate epileptogenic neuronal modulation of the interhemispheric corpus callosum and intrahemispheric subcortical network for ESs. TCC may be a therapeutic option to disconnect the interhemispheric modulation of epileptic networks.

Postoperative persistent fever may be a risk factor for hydrocephalus in hemispherical disconnection surgery

IntroductionHemispherical disconnection surgery such as hemispherotomy or posterior quadrant disconnection (PQD) surgery sometimes induces hydrocephalus. We postulated that some risk factors for postoperative hydrocephalus can be managed perioperatively. The purpose of this study was to clarify and statistically analyze perioperative risk factors for postoperative progressive hydrocephalus. MethodsWe reviewed patients who underwent hemispherotomy or PQD. We compared patients with and without progressive hydrocephalus with multivariate and univariate logistic regression analysis to identify risk factors for hydrocephalus. ResultsTwenty-four patients underwent hemispherectomy or PQD (age: 25 days–45 years old, mean: 13.3 years, median: 8 years, standard deviation: 13.9 years, 14 males). Among them, five patients (21%) required hydrocephalus treatment. Persistent fever was a risk factor for progressive hydrocephalus (multivariate analysis: p = 0.024, univariate analysis: p < 0.001). ConclusionPostoperative persistent fever may be a manageable risk factor for postoperative hydrocephalus in hemispherotomy and PQD surgery.

Posterior Quadrant Disconnection for Sub-Hemispheric Drug Refractory Epilepsy

The posterior quadratic epilepsy (PQE) is a form of a multilobar epilepsy, involving the temporal-parietal and occipital lobes. Basically, epilepsies with localized networks to the posterior temporal, posterior parietal, and occipital lobes can benefit from this type of surgery. Gliosis due to perinatal insult and cortical dysplasis and angiomas in Sturge Weber syndrome involving the PQ have often been cited in the literature as the etiology for PQE. However, before considering surgery, it is important to localize the epileptogenic focus through a complete pre operative work up involving; EEG (Electro-Encephalo-Graphy), video EEG, single photon emission computed tomography (SPECT), positron emission tomography (PET), and magneto encephalography (MEG). Historically, these pathologies were dealt with multi-lobar resections, which were associated with high morbidity and mortality, owing to blood loss, especially in young children, hydrocephalus, and hemosiderosis. Based on the theory of networks involved in epileptogenesis, the concept of disconnection in epilepsy surgery was introduced. Delalande and colleagues, described the technique of hemispheric disconnection (functional hemispherectomy) for pathologies like: hemimegalencephaly, rasmussens encephalitis involving the entire hemisphere. The technique has evolved with time, moving towards minimally invasive endoscopic vertical hemispherotomy, described by Chandra and colleagues.[1],[2] The posterior quadrant disconnection (PQD) evolved as a tailored disconnection on similar lines as hemispherotomy, for managing refractory epilepsy arising from the posterior quadrant.[3] The technique and principles involved in the PQD surgery are similar to the those of peri-insular hemispherotomy and has been described in the literature by few authors.[3],[4],[5],[6] The technique of performing PQD will be described here in a step-wise fashion with illustrations supplemented by a surgical video.

Anatomic Understanding of Posterior Quadrant Disconnection from Cadaveric Brain, 3D Reconstruction and Simulation Model, and Intraoperative Photographs

Posterior quadrant disconnection is a surgery for refractory unilateral temporoparieto-occipital epilepsy to limit propagation of epileptic discharges. As incomplete disconnection can lead to residual seizures, detailed procedures are presented using a cadaveric brain, three-dimensional (3D) reconstruction and simulation models, and intraoperative photographs. A formalin-fixed adult cadaveric brain was dissected to show each step in posterior quadrant disconnection. Using 3D preoperative planning software, we reconstructed 3D models of operative views from computed tomography and magnetic resonance imaging. Intraoperative photographs were taken from the case of a 7-year-old girl with temporoparieto-occipital epilepsy. Frontotemporoparietal craniotomy was performed. The Sylvian fissure was widely dissected, and the insular cortex was exposed. The temporal stem was disconnected along the inferior peri-insular sulcus. The disconnection was extended from the limen insulae to the atrium of the lateral ventricle. The fibers between the head of the hippocampus and the amygdala were disconnected. The parietal lobe was disconnected along the postcentral sulcus, and the disconnection was connected to the atrium of the lateral ventricle. At the medial surface of the parietal lobe, the disconnection was continued to the corpus callosum. The splenium of the corpus callosum was disconnected via the medial wall of the lateral ventricle. The fornix was divided in the atrium of the lateral ventricle. After these steps, disconnection of the unilateral tempoparieto-occipital lobe was achieved while preserving the arteries and veins. Inclusion of views from cadaveric brain, 3D reconstruction and simulation models, and intraoperative photographs facilitates a clearer anatomic understanding of posterior quadrant disconnection.

A case of posterior quadrant disconnection for post-subdural empyema epilepsy -focal cortical dysplasia might be the underlying cause of refractory epilepsy-

Abstract Introduction Intracranial subdural empyema (ISDE) can cause drug-resistant epilepsy. We attempted to cure post-ISDE refractory epilepsy by operative surgery and assessed the neuropathological findings. Patient and method A 23-year-old right-handed man with refractory epilepsy had ISDE on the right temporal and occipital areas at 14 years old. He underwent ISDE drainage operation at the time. A week after the infection, he developed epileptic seizure, which consisted of epigastric sensation, followed by loss of awareness with gelastic seizure. This type of seizure occurred around five times a day. He underwent right posterior disconnection and the temporal lobe was submitted to histopathological examination. Result The patient has remained seizure-free for more than 3 months. Histopathological diagnosis showed focal cortical dysplasia (FCD) type IB. Conclusion We cured post-ISDE refractory epilepsy by posterior quadrant disconnection. Epileptogenicity of FCD might be triggered by ISDE.

Posterior Quadrant Disconnection: A Fiber Dissection Study.

Posterior quadrant disconnection can be highly effective in the surgical treatment of selected cases of refractory epilepsy. The technique aims to deafferent extensive areas of epileptogenic posterior cortex from the rest of the brain by isolating the temporoparietooccipital cortex. To describe this procedure and relevant white matter tracts with a specific emphasis on the extent of callosotomy in an anatomic study. Twenty hemispheres were dissected according to Klingler's fiber dissection technique illustrating the peri-insular (temporal stem, superior longitudinal fasciculus, corona radiata) and mesial disconnection (mesiotemporal cortex, cingulum, and corpus callosum). Extensive white matter tract disconnection is obtained after posterior quadrant disconnection. Callosal fibers connecting the anterior most part of the parietal cortex invariably ran through the isthmus of the corpus callosum and need to be disconnected, while frontal lobe connections including the corticospinal tract and the anterior two-thirds of the corpus callosum are spared during the procedure. Our findings suggest the involvement of both the splenium and the isthmus in interhemispheric propagation in posterior cortex epilepsies. Sectioning the total extent of the posterior one-third of the corpus callosum might therefore be necessary to achieve optimal outcomes in posterior quadrant epilepsy surgery.

Posterior quadrant disconnection surgery for Sturge‐Weber syndrome

Some patients with Sturge-Weber syndrome (SWS) need epilepsy surgery for adequate seizure control and prevention of psychomotor deterioration. The majority of patients with SWS have leptomeningeal angioma located over the temporal, parietal, and occipital lobes. We applied posterior quadrant disconnection surgery for this type of SWS with intractable seizure. We evaluated the efficacy of this procedure in seizure control and psychomotor development. Ten patients who were surgically treated using the posterior quadrantectomy (PQT) were enrolled in this study. Surgical outcome was analyzed as seizure-free or not at 2 years after surgery. Psychomotor development was evaluated by the scores of mental developmental index (MDI) and psychomotor developmental index (PDI) in the Bayley Scales of Infant Development II preoperatively, and at 6 and 12 months after the PQT. Eight of 10 patients were seizure-free. Patients without complete elimination of the angiomatous areas had residual seizures. Average MDI and PDI scores before the surgery were 64.8 and 71.6, respectively. Scores of MDI at 6 and 12 months after the PQT in seizure-free patients were 80.5 and 84.5, respectively (p < 0.01). PDI scores at these postoperative intervals were 87.3 and 86.4, respectively (p < 0.05). Patients with residual seizures did not improve in either MDI or PDI. The PQT achieved good seizure control and improved psychomotor development in patients with SWS. The complete deafferentation of angiomatous areas is required for seizure-free results and psychomotor developmental improvement.

Posterior quadrantic disconnection maintains the activity of isolated temporal-parietal-occipital nerve tissue: neuroprotective measures in the surgical treatment of epilepsy.

Posterior quadrantic disconnection maintains the activity of isolated temporal-parietal-occipital nerve tissue: neuroprotective measures in the surgical treatment of epilepsy.

Posterior quadrant disconnection for refractory epilepsy: A case series.

Objective:To analyze the surgical outcome and safety of posterior quadrant disconnection in medically refractory epilepsy arising from the posterior head region from a level IV tertiary care center over a period of three years.Materials and Methods:Seven consecutive patients who underwent posterior quadrant disconnection for refractory epilepsy were analyzed.Results:We analyzed the data of seven (n = 7) consecutive posterior quadrant epilepsy patients who underwent posterior quadrant disconnection with a mean age of 8.5 years over the last three years of which 4 were male and 3 females. All patients underwent extensive pre-surgical evaluation including detailed history, examination, prolonged video EEG recordings, neuropsychological testing, MRI brain, DTI, PET scan (n = 6), fMRI (n = 4), WADA test (n = 1) and invasive recording (n = 1), Of seven patients four had left sided pathology and three had right sided pathology. All patients except one underwent pure disconnection and one underwent partial resection.Conclusion:Posterior quadrant disconnection is effective surgical procedure for medically refractory epilepsy arising from the posterior quadrant in carefully selected patients without morbidity or functional disability across various age groups especially in children. In our series, all seven patient had good seizure outcome and none had functional disabilities.