Posterior quadrant disconnection surgery for Sturge-Weber syndrome

Disconnection Methods in the Surgical Treatment of Epilepsy

Disconnection procedures in epilepsy surgery have become an important tool for the management of multifocal drug-resistant epilepsy. In this chapter, we will review their indications, describe the technical procedures, and review outcome data in the literature. Among the curative approaches, anterior quadrant disconnection, posterior quadrant (PQ) disconnection, and functional hemispherectomy can be performed for patients whose epileptic focus resides in one hemisphere or one quadrant. Seizure freedom rates from these procedures range from 50 to 81% for anterior quadrant disconnections, 50 to 92% for PQ disconnections, and 43 to 93% for hemispherectomy. Although typically performed in the pediatric population, data suggest that carefully selected adult patients could also benefit from a disconnection procedure. Of the palliative approaches, corpus callosotomy has been shown to be effective for drop attacks, resulting in significant improvement in seizure frequency, severity, and quality of life. Minimally invasive alternatives to standard open corpus callosotomies with laser interstitial thermal therapy (LITT) have been proposed. Overall, surgical disconnection procedures are an effective way of treating multifocal epilepsy, with good outcomes that can improve the quality of life for these patients.

Epilepsy surgery in patients with Sturge-Weber Syndrome

Sturge-Weber Syndrome (SWS) is a neurovascular condition caused by a mutation in the GNAQ gene. The most common neurological manifestations of SWS are epilepsy, developmental delay, and stroke-like episodes. Seizures are often the first neurological symptom, and most patients have drug-resistant epilepsy. Predictors for unfavorable epilepsy outcomes and the need for ASM polytherapy included age of onset, bilateral brain involvement, extensive unilateral hemispheric disease, and a positive family history of epilepsy. The surgical approach to SWS is challenging due to the associated abnormal vasculature and potential complications. Hemispherotomy is associated with high seizure freedom rates and ASM discontinuation, but resective surgery may be an efficient alternative in well-selected patients. Complete seizure control is the ultimate goal of epilepsy surgery; however, reducing seizure severity and frequency may help improve cognitive outcome and quality of life.

Total posterior quadrant disconnection for drug-resistant epilepsy in children

OBJECTIVE

To assess seizure outcomes, prognostic factors, and developmental changes in children undergoing total posterior quadrant disconnection (PQD) for drug-resistant epilepsy (DRE).

METHODS

We 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.

RESULTS

Out 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.

SIGNIFICANCE

For 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 SUMMARY

Due 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.

Disconnection Surgery in Pediatric Epilepsy: A Single Center's Experience With 185 Cases

BACKGROUND AND OBJECTIVES

Lobar and multilobar disconnections have gradually become common surgical methods in pediatric epilepsy surgery in recent years. However, the surgical procedures, postoperative epilepsy outcomes, and complications reported by each center are quite different. To review and analyze the clinical data from lobar disconnection in treating intractable pediatric epilepsy and study the characteristics, surgical outcomes, and safety of different disconnection surgeries.

METHODS

This was a retrospective analysis of 185 children with intractable epilepsy who underwent various lobar disconnections at the Pediatric Epilepsy Center, Peking University First Hospital. Clinical information was grouped according to their characteristics. The differences in the abovementioned characteristics among the different lobar disconnections were summarized, and risk factors affecting the surgical outcome and postsurgical complications were explored.

RESULTS

Among the 185 patients, 149 patients (80.5%) achieved seizure freedom with a follow-up of 2.1 years. There were 145 patients (78.4%) with malformations of cortical development (MCD). The seizure onset time (median 6 months, P = .001) and surgery time (median 34 months, P = .000) of the MCD group were smaller. Differences were found in etiology, resection of the insular lobe and epilepsy outcome among different disconnection approaches. Both parieto-occipital disconnection ( P = .038, odds ratio = 8.126) and MRI abnormalities larger than the disconnection extent ( P = .030, odds ratio = 2.670) affected the epilepsy outcome. Early postoperative complications were observed in 43 patients (23.3%), and long-term postoperative complications were observed in 5 patients (2.7%).

CONCLUSION

The most common etiology of epilepsy in children undergoing lobar disconnection is MCD, whose onset and operative ages are the youngest. Disconnection surgery obtained good seizure outcomes in the treatment of pediatric epilepsy with a low incidence of long-term complications. With advances in presurgical evaluation, disconnection surgery will play a more important role in young children with intractable epilepsy.

Proper Therapy Selection Improves Epilepsy Outcomes in Patients With Multilobar Sturge-Weber Syndrome

BACKGROUND

Hemispherectomy is an optimal treatment for patients with Sturge-Weber syndrome (SWS) affecting the whole hemisphere; however, a consensus has not been reached regarding therapeutic choices for those with involvement of two to three lobes. In this study, we compared seizure and cognitive outcomes between medical and surgical treatment groups in patients with multilobar involvement.

METHODS

We evaluated 50 patients with multilobar involvement. Surgical indications included (1) antiepileptic drug (AED)-resistant seizures; (2) developmental delay; and (3) cortical atrophy. Twenty-nine patients were classified in the medical treatment group (MTG), and 21 patients were in the surgical treatment group (STG). Seizure type and frequency, SWS electroencephalography score (SWS-EEGS), and pretherapeutic and posttherapeutic SWS neurological scores (SWS-NS) were compared between groups. Median ages at the initial evaluation of the MTG and STG were 4 and 2 years, and at the final evaluation were 13 and 17 years, respectively.

RESULTS

The STG had a higher incidence (76.2%) of focal to bilateral tonic-clonic seizures and status epilepticus, although no difference in SWS-EEGS. Seizure and cognitive subcategories of SWS-NS at initial evaluation were worse in the STG (P = 0.025 and P = 0.007). The seizure subcategory in MTG and STG improved after therapy (P = 0.002 and P = 0.001). Cognition was maintained in MTG and improved in STG (P = 0.002). The seizure-free rates in MTG and STG were 58.6% and 85.7%, respectively.

CONCLUSIONS

Appropriate therapeutic choices improved seizure outcomes. Although patients who required surgery had more severe epilepsy and cognitive impairment, surgery improved both.

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

BACKGROUND

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.

OBJECTIVE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

Characteristics, surgical outcomes, and influential factors of epilepsy in Sturge-Weber syndrome

Few studies have reported the clinical presentation, surgical treatment, outcomes and influential factors for patients with epilepsy and Sturge-Weber syndrome. This large-scale retrospective study continuously enrolled 132 patients with Sturge-Weber syndrome and epilepsy from January 2008 to December 2018 at our hospital to analyse their characteristics. Among these patients, 90 underwent epilepsy surgery, and their postoperative 2-year follow-up seizure, cognitive and motor functional outcomes were assessed and analysed. Univariable and multivariable logistic analyses were conducted to explore the influential factors. Among the patients with Sturge-Weber syndrome for whom characteristics were analysed (n = 132), 76.52% of patients had their first epileptic seizures within their first year of life. The risk factors for cognitive decline were seizure history ≥ 2 years [adjusted odds ratio (aOR) = 3.829, 95% confidence interval (CI): 1.810-9.021, P = 0.008)], bilateral leptomeningeal angiomas (aOR = 3.173, 95% CI: 1.970-48.194, P = 0.013), age at onset <1 year (aOR = 2.903, 95% CI: 1.230-6.514, P = 0.013), brain calcification (aOR = 2.375, 95% CI: 1.396-5.201, P = 0.021) and left leptomeningeal angiomas (aOR = 2.228, 95% CI: 1.351-32.571, P = 0.030). Of the patients who underwent epilepsy surgery (n = 90), 44 were subject to focal resection, and 46 underwent hemisphere surgery (19 anatomical hemispherectomies and 27 modified hemispherotomies). A postoperative seizure-free status, favourable cognitive outcomes, and favourable motor outcomes were achieved in 83.33%, 44.44% and 43.33% of surgical patients, respectively. The modified hemispherotomy group had similar surgical outcomes, less intraoperative blood loss and shorter postoperative hospital stays than the anatomical hemispherectomy group. Regarding seizure outcomes, full resection (aOR = 11.115, 95% CI: 1.260-98.067, P = 0.020) and age at surgery < 2 years (aOR = 6.040, 95% CI: 1.444-73.367, P = 0.031) were positive influential factors for focal resection. Age at surgery < 2 years (aOR = 15.053, 95% CI: 1.050-215.899, P = 0.036) and infrequent seizures (aOR = 8.426, 95% CI: 1.086-87.442, P = 0.042; monthly versus weekly) were positive influential factors for hemisphere surgery. In conclusion, epilepsy surgery resulted in a good postoperative seizure-free rate and favourable cognitive and motor functional outcomes and showed acceptable safety for patients with epilepsy and Sturge-Weber syndrome. Modified hemispherotomy is a less invasive and safer type of hemisphere surgery than traditional anatomic hemispherectomy with similar surgical outcomes. Early surgery may be helpful to achieve better seizure outcomes and cognitive protection, while the risk of surgery for young children should also be considered.

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.

Dynamic tractography-based localization of spike sources and animation of spike propagations

OBJECTIVE

This study was undertaken to build and validate a novel dynamic tractography-based model for localizing interictal spike sources and visualizing monosynaptic spike propagations through the white matter.

METHODS

This cross-sectional study investigated 1900 spike events recorded in 19 patients with drug-resistant temporal lobe epilepsy (TLE) who underwent extraoperative intracranial electroencephalography (iEEG) and resective surgery. Twelve patients had mesial TLE (mTLE) without a magnetic resonance imaging-visible mass lesion. The remaining seven had a mass lesion in the temporal lobe neocortex. We identified the leading and lagging sites, defined as those initially and subsequently (but within ≤50 ms) showing spike-related augmentation of broadband iEEG activity. In each patient, we estimated the sources of 100 spike discharges using the latencies at given electrode sites and diffusion-weighted imaging-based streamline length measures. We determined whether the spatial relationship between the estimated spike sources and resection was associated with postoperative seizure outcomes. We generated videos presenting the spatiotemporal change of spike-related fiber activation sites by estimating the propagation velocity using the streamline length and spike latency measures.

RESULTS

The spike propagation velocity from the source was 1.03 mm/ms on average (95% confidence interval = .91-1.15) across 133 tracts noted in the 19 patients. The estimated spike sources in mTLE patients with International League Against Epilepsy Class 1 outcome were more likely to be in the resected area (83.9% vs. 72.3%, φ = .137, p < .001) and in the medial temporal lobe region (80.5% vs. 72.5%, φ = .090, p = .002) than those associated with the Class ≥2 outcomes. The resulting video successfully animated spike propagations, which were confined within the temporal lobe in mTLE but involved extratemporal lobe areas in lesional TLE.

SIGNIFICANCE

We have, for the first time, provided dynamic tractography visualizing the spatiotemporal profiles of rapid propagations of interictal spikes through the white matter. Dynamic tractography has the potential to serve as a unique epilepsy biomarker.

Total and partial posterior quadrant disconnection for medically refractory epilepsy: A systematic review

PURPOSE

Posterior quadrant disconnection (PQD) is a surgical procedure for medically refractory epilepsy (MRE) involving diffuse regions of the temporo-parieto-occipital lobes. We sought to compare factors and efficacy according to PQD extent.

METHODS

We performed a systematic review of the literature reporting the use of PQD since 2004. We analyzed various characteristics of pooled cases, including the role of preoperative studies in patient selection, intraoperative techniques, and outcomes.

RESULTS

Our review of 137 patients from nine studies revealed 66% undergoing total PQD and 34% undergoing partial PQD. Interictal electroencephalography (EEG) findings were predominantly characterized as lateralized for total PQD (56%) and localized within the ipsilateral posterior quadrant in patients undergoing partial PQD (53%). Metabolic functional studies [positron emission tomography (PET) or ictal single-photon emission computed tomography (SPECT)] played a role in surgical decision-making in 42% of patients who underwent total PQD. Wada and/or functional magnetic resonance imaging (fMRI) was more often utilized for partial PQD (22%) than total PQD (3%) as was intracranial electroencephalography (icEEG) (30% versus 13%, respectively). Overall, 75% of total PQD patients achieved seizure freedom [defined as Engel I or International League Against Epilepsy (ILAE) Class 1 outcome] in comparison to 63% of partial PQD patients (p = .078). New visual field deficits were seen in 12% and new or worsened hemiparesis in 6%. For patients in either cohort, concordance of interictal and ictal EEG findings was found to be predictive of seizure freedom (p = .048).

CONCLUSION

Both total and partial PQD represent effective alternatives for managing patients with MRE whose seizure onset zone (SOZ) involves a diffuse region within the posterior quadrant. While PET and/or SPECT frequently aided in the decision to proceed with total PQD, patients who underwent a tailored, partial multilobar resection were more likely to undergo Wada and/or fMRI testing as well as stage I icEEG studies.

Extent of Leptomeningeal Capillary Malformation is Associated With Severity of Epilepsy in Sturge-Weber Syndrome

BACKGROUND

Individuals with Sturge-Weber syndrome (SWS) often expereince intractable epilepsy and cognitive decline. We hypothesized that the extent of the leptomeningeal capillary malformation (LCM) may correlate with the severity of neurological impairment due to SWS. We tested the hypothesis in a cross-sectional study of seizure severity and electroencephalographic (EEG) findings and a retrospective cohort study for surgical indications related to the extent of the LCM.

METHODS

We enrolled 112 patients and classified them according to LCM distribution: (1) bilateral, (2) hemispheric, (3) multilobar, and (4) single lobe. Age at seizure onset, seizure semiology and frequency, and EEG findings were compared. Surgical indications were evaluated for each group by Fisher exact test, and predictors for surgery were evaluated by univariate and multivariate analyses. Therapeutic efficacy was evaluated by the SWS-Neurological Score (SWS-NS).

RESULTS

The bilateral and hemispheric groups had early seizure onset (4.0 months old and 3.0 months old), frequent seizures (88.9% and 80.6% had more than one per month), focal-to-bilateral tonic-clonic seizures (88.9% and 74.2%), and status epilepticus (100% and 87.1%). The groups' EEG findings did not differ substantially. Surgical indications were present in 77.8% of the bilateral, 88.1% of the hemispheric, and 46.8% of the multilobar groups. Seizure more than once per month was a predictor of surgical treatment. Seizure subscore improved postoperatively in the hemispheric and multilobar groups. Even after surgical treatment, the bilateral and hemispheric groups exhibited higher SWS-NSs than members of the other groups.

CONCLUSION

Our study demonstrated a strong association between extensive LCM and epilepsy severity. Surgical intervention improved seizure outcome in patients with SWS with large LCMs.

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.

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

OBJECTIVE

To evaluate the effectiveness of frontal disconnection surgery in seizure control and related consequences in a consecutive patient series.

METHODS

We conducted a retrospective analysis of patients who underwent frontal disconnection surgery for drug-resistant epilepsy (DRE). Baseline epilepsy characteristics, detailed presurgical evaluation including epileptogenic zone (EZ) localization, magnetic resonance imaging (MRI) detection of epileptogenic lesion, and pathological findings were reviewed. Patients were followed postoperatively for seizure outcome at 1 year.

RESULTS

A total of 16 patients were identified (six children and 10 adults). Most patients had a childhood onset of DRE with a median duration of epilepsy of 6.5 years (interquartile range 3.5-17.5 years) before surgery. In 10 (62.5%) patients, the EZ was localized to the frontal lobe, while in six patients, the EZ involved also adjacent lobes or consisted of multiple foci. In 10 (62.5%) patients, an epileptogenic lesion was detected on presurgical MRI, four of which (40%) had all MRI abnormalities confined to the frontal lobe. Two-thirds of the patients (11/16; 68.8%) underwent isolated frontal disconnection procedure, while remaining patients had frontal disconnection combined with resection of an adjacent lobe. Of the 12 patients in whom biopsy was taken from the disconnected frontal lobe, six (50%) had pathology-proven focal cortical dysplasia. We observed surgical-related complications in three (18.8%) cases, neurological deficits in other three (18.8%) patients, and worsening cognitive abilities in one (6.3%) patient. Overall, eight (50%) patients became completely seizure-free (ILAE 1) at one-year follow-up.

SIGNIFICANCE

Frontal disconnection surgery for DRE can result in seizure freedom in certain patients, especially when the EZ is strictly limited to the ipsilateral frontal region, and the MRI shows an epileptogenic lesion that is purely frontal in location. Frontal lobe disconnection procedure is safe and has a limited complication rate. However, further studies with larger patient population will yield more significance.

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.

Tailored multilobar disconnective epilepsy surgery in the posterior quadrant

OBJECTIVE

Surgical treatment of drug-resistant epilepsy originating from the posterior quadrant (PQ) of the brain often requires large multilobar resections, and disconnective techniques have been advocated to limit the risks associated with extensive tissue removal. Few previous studies have described a tailored temporoparietooccipital (TPO) disconnective approach; only small series with short postoperative follow-ups have been reported. The aim of the present study was to present a tailored approach to multilobar PQ disconnections (MPQDs) for epilepsy and to provide details about selection of patients, presurgical investigations, surgical technique, treatment safety profile, and seizure and cognitive outcome in a large, single-center series of patients with a long-term follow-up.

METHODS

In this retrospective longitudinal study, the authors searched their prospectively collected database for patients who underwent MPQD for drug-resistant epilepsy in the period of 2005-2017. Tailored MPQDs were a posteriori grouped as follows: type I (classic full TPO disconnection), type II (partial TPO disconnection), type III (full temporooccipital [TO] disconnection), and type IV (partial TO disconnection), according to the disconnection plane in the occipitoparietal area. A bivariate statistical analysis was carried out to identify possible predictors of seizure outcome (Engel class I vs classes II-IV) among several presurgical, surgical, and postsurgical variables. Preoperative and postoperative cognitive profiles were also collected and evaluated.

RESULTS

Forty-two consecutive patients (29 males, 24 children) met the inclusion criteria. According to the presurgical evaluation (including stereo-electroencephalography in 13 cases), 12 (28.6%), 24 (57.1%), 2 (4.8%), and 4 (9.5%) patients received a type I, II, III, or IV MPQD, respectively. After a mean follow-up of 80.6 months, 76.2% patients were in Engel class I at last contact; at 6 months and 2 and 5 years postoperatively, Engel class I was recorded in 80.9%, 74.5%, and 73.5% of cases, respectively. Factors significantly associated with seizure freedom were the occipital pattern of seizure semiology and the absence of bilateral interictal epileptiform abnormalities at the EEG (p = 0.02). Severe complications occurred in 4.8% of the patients. The available neuropsychological data revealed postsurgical improvement in verbal domains, whereas nonunivocal outcomes were recorded in the other functions.

CONCLUSIONS

The presented data indicate that the use of careful anatomo-electro-clinical criteria in the presurgical evaluation allows for customizing the extent of surgical disconnections in PQ epilepsies, with excellent results on seizures and an acceptable safety profile.

A case report of a pregnant woman with Sturge-Weber syndrome

A 23-year-old pregnant woman presented with headache and paroxysmal spasm of the right limb. She was born with a port-wine birthmark around the left eye frame. Magnetic resonance imaging revealed evidence of atrophy, calcification and vascular malformation in the left cerebral hemisphere. She was diagnosed with Sturge-Weber syndrome. She gave birth to a child without a port-wine birthmark through a caesarean section and her headache eased without surgical intervention of the intracranial vessel hyperplasia. This case suggests that pregnant women with SWS can deliver safely.

Anatomic Understanding of Subtotal Hemispherotomy Using Cadaveric Brain, 3-Dimensional Simulation Models, and Intraoperative Photographs

BACKGROUND

When the epileptogenic foci skip the motor area, the epilepsy can be cured by surgery while preserving the motor function. This surgery has been reported as subtotal hemispherectomy. The disconnective variant of this surgery, subtotal hemispherotomy, is described.

OBJECTIVE

To demonstrate each step clearly, a cadaveric brain, 3-dimensional reconstruction and simulation model, and intraoperative photographs were used.

METHODS

A formalin-fixed cadaveric brain was dissected to show each step of this surgery. For the 3-dimensional model, several brain structures were reconstructed from preoperative images, and the surgery was simulated. Intraoperative photographs and postoperative magnetic resonance images were taken from the representative cases.

RESULTS

Temporo-parieto-occipital disconnection is performed to disconnect these lobes and the insula, limbic system, and splenium of the corpus callosum. The postcentral sulcus is the anterior border of the disconnection. Next, prefrontal disconnection is performed to disconnect the frontal lobe and the insula, frontal lobe and basal ganglia, and the anterior part of the corpus callosum. The precentral sulcus is the posterior border of the disconnection. Finally, corpus callosotomy of the central part is performed. After these steps, subtotal hemispherotomy, with preservation of the pre- and postcentral gyrus, is achieved. The 3-dimensional model clearly shows the anatomic relationships between deep brain structures. In the representative cases, postoperative motor deterioration was transient or none, and seizure-free status was achieved after surgery.

CONCLUSION

Subtotal hemispherotomy is generally difficult because of the complicated anatomy and narrow and deep surgical corridors. Combined use of these methods facilitates a clearer understanding of this surgery.

Seizure and cognitive outcomes of posterior quadrantic disconnection: a series of 12 pediatric patients

Purpose: To evaluate surgical outcomes and cognitive improvements after posterior quadrantic disconnection (PQD) in children who had medically intractable epilepsy and to compare the various characteristics between the acquired group and the developmental group.Method: Between 2015 and 2017, we retrospectively enrolled all pediatric patients who underwent PQD. We used image post-processing techniques for preoperative evaluation. Seizure outcomes and postoperative cognitive improvements were analysed. The patients were divided into the acquired group and the developmental group depending on the pathology; we then compared groups regarding age at onset, surgery, history, and seizure and cognitive outcomes.Results: A total of 12 pediatric patients were enrolled, including 7 acquired patients and 5 developmental patients. After a median 28.9-month follow-up, 11 (91.7%) of 12 patients were seizure free. The image post-processing facilitated a better visualization on preoperative evaluation and helped with detection of the epileptogenic zone. There were significant linear relationships between improvements in IQ and operative age (R²=0.527, p = 0.007) and IQ and epileptic history (R²=0.696, p = 0.001). The median age at seizure onset was 4.86 ± 2.12 years in the acquired group and 2.40 ± 1.14 years in the developmental group (t = 2.344, p = 0.028). Epileptic histories, seizure outcomes and cognitive outcomes were not significantly different between groups.Conclusion: Posterior quadrantic disconnection is an effective epilepsy surgery in selected patients. The use of image post-processing is important for preoperative evaluation. The age at seizure onset and surgery in malformation of cortical development (MCD) patients was earlier; however, the seizure outcome was no better than in acquired pathology patients. Early surgery did not change seizure outcomes but improved cognition.

Operative posterior disconnection in epilepsy surgery: Experience with 29 patients

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.

Neurosurgical approaches to pediatric epilepsy: Indications, techniques, and outcomes of common surgical procedures

Epilepsy is a common pediatric neurological condition, and approximately one-third of children with epilepsy are refractory to medical management. For these children neurosurgery may be indicated, but operative success is dependent on complete delineation of the epileptogenic zone. In this review, surgical techniques for pediatric epilepsy are considered. First, potentially-curative operations are discussed and broadly divided into resections and disconnections. Then, two palliative approaches to seizure control are reviewed. Finally, future neurosurgical approaches to epilepsy are considered.

Posterior Quadrant Disconnection: A Fiber Dissection Study

BACKGROUND

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.

OBJECTIVE

To describe this procedure and relevant white matter tracts with a specific emphasis on the extent of callosotomy in an anatomic study.

METHODS

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).

RESULTS

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.

CONCLUSION

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.

Complete prefrontal lobe isolation surgery for recurrent epilepsy: A case report

Epileptogenic focus resection is less effective for the treatment of frontal lobe epilepsy compared with temporal lobe epilepsy. However, there is currently a lack of effective therapeutic options for patients with frontal lobe epilepsy who are unsuitable for epileptogenic focus resection (such patients with epileptogenic foci in one frontal lobe in which the precise epileptic foci cannot be determined), or who experience recurrent epilepsy following epileptogenic focus resection. The present study reports a patient with frontal lobe epilepsy who underwent successful frontal lobe isolation surgery following a previous unsuccessful epileptogenic focus resection surgery. To ensure complete isolation of the prefrontal lobe, the surgery included division of the anterior commissure and the anterior part of the corpus callosum. The patient was followed-up for 16 months. Although the follow-up electroencephalogram presented a number of sharp waves on the affected side, the patient did not experience any seizures. The results suggest that prefrontal lobe isolation is an effective method of treating frontal lobe epilepsy, as division of the anterior commissure and the anterior part of the corpus callosum ensures disconnection of the prefrontal lobe from other regions of the brain.

Analysis of Epileptic Discharges from Implanted Subdural Electrodes in Patients with Sturge-Weber Syndrome

OBJECTIVE

Almost two-thirds of patients with Sturge-Weber syndrome (SWS) have epilepsy, and half of them require surgery for it. However, it is well known that scalp electroencephalography (EEG) does not demonstrate unequivocal epileptic discharges in patients with SWS. Therefore, we analyzed interictal and ictal discharges from intracranial subdural EEG recordings in patients treated surgically for SWS to elucidate epileptogenicity in this disorder.

METHODS

Five intractable epileptic patients with SWS who were implanted with subdural electrodes for presurgical evaluation were enrolled in this study. We examined the following seizure parameters: seizure onset zone (SOZ), propagation speed of seizure discharges, and seizure duration by visual inspection. Additionally, power spectrogram analysis on some frequency bands at SOZ was performed from 60 s before the visually detected seizure onset using the EEG Complex Demodulation Method (CDM).

RESULTS

We obtained 21 seizures from five patients for evaluation, and all seizures initiated from the cortex under the leptomeningeal angioma. Most of the patients presented with motionless staring and respiratory distress as seizure symptoms. The average seizure propagation speed and duration were 3.1 ± 3.6 cm/min and 19.4 ± 33.6 min, respectively. Significant power spectrogram changes at the SOZ were detected at 10-30 Hz from 15 s before seizure onset, and at 30-80 Hz from 5 s before seizure onset.

SIGNIFICANCE

In patients with SWS, seizures initiate from the cortex under the leptomeningeal angioma, and seizure propagation is slow and persists for a longer period. CDM indicated beta to low gamma-ranged seizure discharges starting from shortly before the visually detected seizure onset. Our ECoG findings indicate that ischemia is a principal mechanism underlying ictogenesis and epileptogenesis in SWS.

Mosaic Neurocutaneous Disorders and Their Causes

Neurocutaneous disorders are a heterogeneous group of conditions (mainly) affecting the skin [with pigmentary/vascular abnormalities and/or cutaneous tumours] and the central and peripheral nervous system [with congenital abnormalities and/or tumours]. In a number of such disorders, the skin abnormalities can assume a mosaic patterning (usually arranged in archetypical patterns). Alternating segments of affected and unaffected skin or segmentally arranged patterns of abnormal skin often mirror similar phenomena occurring in extra-cutaneous organs/tissues [eg, eye, bone, heart/vessels, lung, kidney and gut]. In some neurocutaneous syndromes the abnormal mosaic patterning involve mainly the skin and the nervous system configuring a (true) mosaic neurocutaneous disorder; or an ordinary trait of a neurocutaneous disorder is sometimes superimposed by a pronounced linear or otherwise segmental involvement; or, lastly, a neurocutaneous disorder can occur solely in a mosaic pattern. Recently, the molecular genetic and cellular bases of an increasing number of neurocutaneous disorders have been unravelled, shedding light on the interplays between common intra- and extra-neuronal signalling pathways encompassing receptor-protein and protein-to-protein cascades (eg, RAS, MAPK, mTOR, PI3K/AKT and GNAQ pathways), which are often responsible of the mosaic distribution of cutaneous and extra-cutaneous features. In this article we will focus on the well known, and less defined mosaic neurocutaneous phenotypes and their related molecular/genetic bases, including the mosaic neurofibromatoses and their related forms (ie, spinal neurofibromatosis and schwannomatosis); Legius syndrome; segmental arrangements in tuberous sclerosis; Sturge-Weber and Klippel-Trenaunay syndromes; microcephaly/megalencephaly-capillary malformation; blue rubber bleb nevus syndrome; Wyburn-Mason syndrome; mixed vascular nevus syndrome; PHACE syndrome; Incontinentia pigmenti; pigmentary mosaicism of the Ito type; neurocutaneous melanosis; cutis tricolor; speckled lentiginous syndrome; epidermal nevus syndromes; Becker's nevus syndrome; phacomatosis pigmentovascularis and pigmentokeratotica; Proteus syndrome; and encephalocraniocutaneous lipomatosis.

Systematic review of the efficacy in seizure control and safety of neuronavigation in epilepsy surgery: The need for well-designed prospective studies

PURPOSE

To evaluate the efficacy of surgery with neuronavigation compared to conventional neurosurgical treatment of epilepsy in terms of safety and seizure outcomes and to assess the quality of the evidence base of neuronavigation in this clinical context.

METHOD

Systematic review using the electronic databases of Cochrane, CRD, PubMed, Embase, SciELO and LILACS in Portuguese, English and Spanish. The [MeSH] terms included "epilepsy" and "neuronavigation".

ELIGIBILITY CRITERIA

Studies assessing surgery with neuronavigation for the surgical treatment of epilepsy or brain injuries associated with epileptic seizures.

RESULTS

We identified 28 original articles. All articles yielded scientific evidence of low quality. Outcome data presented in the articles identified was heterogeneous and did not amount to compelling evidence that epilepsy surgery with neuronavigation produces higher rates of seizure control, a reduced need for reoperations, or lower rates of complications or postoperative neurological deficits.

CONCLUSION

We were unable to find any publications providing convincing evidence that neuronavigation improves outcomes of epilepsy surgery. Whilst this does not mean that neuronavigation cannot improve neurosurgical outcomes in this clinical setting, well-designed research studies evaluating the role of neuronavigation are urgently needed.

Epilepsy surgery for pediatric epilepsy: optimal timing of surgical intervention

Pediatric epilepsy has a wide variety of etiology and severity. A recent epidemiological study suggested that surgery might be indicated in as many as 5% of the pediatric epilepsy population. Now, we know that effective epilepsy surgery can result in seizure freedom and improvement of psychomotor development. Seizure control is the most effective way to improve patients neurologically and psychologically. In this review, we look over the recent evidence related to pediatric epilepsy surgery, and try to establish the optimal surgical timing for patients with intractable epilepsy. Appropriate surgical timing depends on the etiology and natural history of the epilepsy to be treated. The most common etiology of pediatric intractable epilepsy patients is malformation of cortical development (MCD) and early surgery is recommended for them. Patients operated on earlier than 12 months of age tended to improve their psychomotor development compared to those operated on later. Recent progress in neuroimaging and electrophysiological studies provide the possibility of very early diagnosis and comprehensive surgical management even at an age before 12 months. Epilepsy surgery is the only solution for patients with MCD or other congenital diseases associated with intractable epilepsy, therefore physicians should aim at an early and precise diagnosis and predicting the future damage, consider a surgical solution within an optimal timing.

Epilepsy surgery: current status and ongoing challenges

This article reviews the current status of surgical treatment of epilepsy and introduces the ongoing challenges. Seizure outcome of resective surgery for focal seizures associated with focal lesions is satisfactory. Particularly for mesial temporal lobe epilepsy, surgical treatment should be considered from the earlier stage of the disease. Meanwhile, surgical outcome in nonlesional extratemporal lobe epilepsy is still to be improved using various approaches. Disconnective surgeries reduce surgical complications of extensive resections while achieving equivalent or better seizure outcomes. Multiple subpial transection is still being modified expecting a better outcome by transection to the vertical cortices along the sulci- and multi-directional transection from a single entry point. Hippocampal transection is expected to preserve memory function while interrupting the abnormal epileptic synchronization. Proper selection or combination of subdural and depth electrodes and a wide-band analysis of electroencephalography may improve the accurate localization of epileptogenic region. Patients for whom curative resective surgery is not indicated because of generalized or bilateral multiple nature of their epilepsies, neuromodulation therapies are options of treatment which palliate their seizures.