Multiple subpial transections: outcome and complications in 20 patients who did not undergo resection

Ultrasound-Navigated Multiple Hippocampal Transections: An Anatomical Study

BACKGROUND

 Multiple hippocampal transection (MHT) is a surgical technique used for the treatment of drug-resistant mesial temporal lobe epilepsy in situations where standard procedures would pose a high risk for memory deterioration. During MHT, the longitudinal fibers of the hippocampus, implicated in epilepsy spreading, are interrupted, while the transverse memory circuits are spared. The extent of MHT is governed by intraoperative electrocorticography; abolition of epileptic discharges serves as an end point to terminate the transection. In other words, the aim of MHT is not the anatomical completeness of hippocampal transection. In contrast, we hypothesize that only the complete transection of hippocampal cross-section is needed to durably terminate epilepsy, avoiding possible postoperative reorganization of longitudinal pathways. Here, we report an anatomical study designed to evaluate the feasibility of complete transection of hippocampus with the aid of ultrasound neuronavigation and we propose new instruments to reach this goal.

METHODS

 Five cadaveric brains were analyzed in this study. MHT was performed on both sides of each brain either with or without ultrasound neuronavigation. The percentage of transected cross-section of the hippocampus was measured using magnetic resonance imaging (MRI) and both sides were compared.

RESULTS

 The ultrasound-guided MHTs were more likely to achieve complete hippocampal transection compared with the nonnavigated MHT transection (73 vs 58%; p < 0.01). Our study also allowed us to propose specialized transectors to minimize invasivity of this procedure.

CONCLUSION

 Completeness of MHT can be better reached with the aid of an ultrasound neuronavigation system; modified instruments for this procedure were also designed.

Surgical approaches to refractory central lobule epilepsy: a systematic review on the role of resection, ablation, and stimulation in the contemporary era

OBJECTIVE

Epilepsy originating from the central lobule (i.e., the primary sensorimotor cortex) is a challenging entity to treat given its involvement of eloquent cortex. The objective of this study was to review available evidence on treatment options for central lobule epilepsy.

METHODS

A comprehensive literature search (PubMed/Medline, EMBASE, and Scopus) was conducted for studies (1990 to date) investigating postoperative outcomes for central lobule epilepsy. The primary and secondary endpoints were seizure freedom at last follow-up and postoperative neurological deficit, respectively. The following procedures were included: open resection, multiple subpial transections (MSTs), laser and radiofrequency ablation, deep brain stimulation (DBS), responsive neurostimulation (RNS), and continuous subthreshold cortical stimulation (CSCS).

RESULTS

A total of 52 studies and 504 patients were analyzed. Most evidence was based on open resection, yielding a total of 400 patients (24 studies), of whom 62% achieved seizure freedom at a mean follow-up of 48 months. A new or worsened motor deficit occurred in 44% (permanent in 19%). Forty-six patients underwent MSTs, of whom 16% achieved seizure freedom and 30% had a neurological deficit (permanent in 12%). There were 6 laser ablation cases (cavernomas in 50%) with seizure freedom in 4 patients and 1 patient with temporary motor deficit. There were 5 radiofrequency ablation cases, with 1 patient achieving seizure freedom, 2 patients each with Engel class III and IV outcomes, and 2 patients with motor deficit. The mean seizure frequency reduction at the last follow-up was 79% for RNS (28 patients), 90% for CSCS (15 patients), and 73% for DBS (4 patients). There were no cases of temporary or permanent neurological deficit in the CSCS or DBS group.

CONCLUSIONS

This review highlights the safety and efficacy profile of resection, ablation, and stimulation for refractory central lobe epilepsy. Resection of localized regions of epilepsy onset zones results in good rates of seizure freedom (62%); however, nearly 20% of patients had permanent motor deficits. The authors hope that this review will be useful to providers and patients when tailoring decision-making for this intricate pathology.

Palliative Epilepsy Surgery Procedures in Children

Surgical treatment of epilepsy typically focuses on identification of a seizure focus with subsequent resection and/or disconnection to "cure" the patient's epilepsy and achieve seizure freedom. Palliative epilepsy surgery modalities are efficacious in improving seizure frequency, severity, and quality of life. In this paper, we review palliative epilepsy surgical options for children: vagus nerve stimulation, responsive neurostimulation, deep brain stimulation, hemispherotomy, corpus callosotomy, lobectomy and/or lesionectomy and multiple subpial transection. Reoperation after surgical resection should also be considered. If curative resection is not a viable option for seizure freedom, these methods should be considered with equal emphasis and urgency in the treatment of drug-resistant epilepsy.

Multiple Subpial Transections for Medically Refractory Epilepsy: A Disaggregated Review of Patient-Level Data

BACKGROUND

Multiple subpial transections (MST) are a treatment for seizure foci in nonresectable eloquent areas.

OBJECTIVE

To systematically review patient-level data regarding MST.

METHODS

Studies describing patient-level data for MST procedures were extracted from the Medline and PubMed databases, yielding a synthetic cohort of 212 patients from 34 studies. Data regarding seizure outcome, patient demographics, seizure type, surgery type, and complications were extracted and analyzed.

RESULTS

Seizure freedom was achieved in 55.2% of patients undergoing MST combined with resection, and 23.9% of patients undergoing MST alone. Significant predictors for seizure freedom were a temporal lobe focus (odds ratio 4.9; 95% confidence interval 1.71, 14.3) and resection of portions of the focus, when feasible (odds ratio 3.88; 95% confidence interval 2.02, 7.45). Complications were frequent, with transient mono- or hemiparesis affecting 19.8% of patients, transient dysphasia 12.3%, and permanent paresis or dysphasia in 6.6% and 1.9% of patients, respectively.

CONCLUSION

MST is an effective treatment for refractory epilepsy in eloquent cortex, with greater chances of seizure freedom when portions of the focus are resected in tandem with MST. The reported rates of seizure freedom with MST are higher than those of existing neuromodulatory therapies, such as vagus nerve stimulation, deep brain stimulation, and responsive neurostimulation, though these latter therapies are supported by randomized-controlled trials, while MST is not. The reported complication rate of MST is higher than that of resection and neuromodulatory therapies. MST remains a viable option for the treatment of eloquent foci, provided a careful risk-benefit analysis is conducted.

A brief history of cortical functional localization and its relevance to neurosurgery

Modern cortical mapping is a cornerstone for safe supratentorial glioma resection in eloquent brain and allows maximal resection with improved functional outcomes. The unlocking of brain functionality through close observation and eventually via cortical stimulation has a fascinating history and was made possible by contributions from early physician-philosophers and neurosurgery’s founding fathers. Without an understanding of brain function and functional localization, none of today’s modern cortical mapping would be possible.

In Vivo Femtosecond Laser Subsurface Cortical Microtransections Attenuate Acute Rat Focal Seizures

Recent evidence shows that seizures propagate primarily through supragranular cortical layers. To selectively modify these circuits, we developed a new technique using tightly focused, femtosecond infrared laser pulses to make as small as ~100 µm-wide subsurface cortical incisions surrounding an epileptic focus. We use this "laser scalpel" to produce subsurface cortical incisions selectively to supragranular layers surrounding an epileptic focus in an acute rodent seizure model. Compared with sham animals, these microtransections completely blocked seizure initiation and propagation in 1/3 of all animals. In the remaining animals, seizure frequency was reduced by 2/3 and seizure propagation reduced by 1/3. In those seizures that still propagated, it was delayed and reduced in amplitude. When the recording electrode was inside the partially isolated cube and the seizure focus was on the outside, the results were even more striking. In spite of these microtransections, somatosensory responses to tail stimulation were maintained but with reduced amplitude. Our data show that just a single enclosing wall of laser cuts limited to supragranular layers led to a significant reduction in seizure initiation and propagation with preserved cortical function. Modification of this concept may be a useful treatment for human epilepsy.

Surgery for epilepsy in the primary motor cortex: A critical review

Surgical resection of the epileptogenic zone within the frontal lobe can be a very effective treatment for medically refractory epilepsy originating from this area. While much of the frontal lobe consists of highly eloquent tissue, surgery is not necessarily contraindicated as long as the epileptogenic zone is well-localized and the tissue resected is limited. Resection of the primary motor cortex was described by Victor Horsley in the 19th century and was used frequently in the early 20th century for a variety of neurological disorders including epilepsy; improvements in surgical techniques and mapping has led to a resurgence of its use in the past few decades. Although many surgeons are hesitant to resect tissue adjacent to the primary hand area based on fears of new motor deficits, there is extensive evidence that focal resections are well-tolerated over the long-term with residual weakness that is fairly mild: some patients experience postoperative weakness, including hemiparesis, but a stereotypical recovery of strength from proximal to distal muscles occurs over months, and only one quarter will have a permanent neurologic deficit, usually consisting of difficulty with fine motor movements. The main alternative to surgical resection is subpial transection, characterized by a small decrease in postoperative deficits and significantly worse seizure outcomes. The treatment of patients with seizures originating from this region requires a solid understanding of the structural and functional anatomy of the frontal lobe.

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.

Subpial transection surgery for epilepsy

BACKGROUND

Nearly 30% of patients with epilepsy continue to have seizures despite using several antiepileptic drugs (AEDs). Such patients are regarded as having refractory, or uncontrolled, epilepsy. While there is no universally accepted definition of uncontrolled, or medically refractory, epilepsy, for the purposes of this review we will consider seizures as drug resistant if they have failed to respond to a minimum of two AEDs. Specialists consider that early surgical intervention may prevent seizures at a younger age, which in turn may improve the intellectual and social status of children. Many types of surgery are available for treating refractory epilepsy; one such procedure is known as subpial transection.

OBJECTIVES

To assess the effects of subpial transection for focal-onset seizures and generalised tonic-clonic seizures in children and adults.

SEARCH METHODS

For the latest update we searched the following databases on 7 August 2018: the Cochrane Register of Studies (CRS Web), which includes the Cochrane Epilepsy Group Specialized Register and the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid, 1946 to August 06, 2018), ClinicalTrials.gov, and the WHO International Clinical Trials Registry Platform (ICTRP). We imposed no language restrictions.

SELECTION CRITERIA

We considered all randomised and quasi-randomised parallel-group studies, whether blinded or non-blinded.

DATA COLLECTION AND ANALYSIS

Two review authors (BK and SR) independently screened trials identified by the search. The same two review authors planned to independently assess the methodological quality of studies. Had we identified studies for inclusion, one review author would have extracted the data, and the other would have verified the data.

MAIN RESULTS

We found no relevant studies.

AUTHORS' CONCLUSIONS

We found no evidence to support or refute the use of subpial transection surgery for patients with medically refractory epilepsy. Well-designed randomised controlled trials are needed to guide clinical practice.

Subpial transection surgery for epilepsy

BACKGROUND

Nearly 30% of patients with epilepsy continue to have seizures in spite of using several antiepileptic drug (AED) regimens. Such patients are regarded as having refractory, or uncontrolled, epilepsy. No definition of uncontrolled, or medically refractory, epilepsy has been universally accepted, but for the purposes of this review, we will consider seizures as drug resistant if they have failed to respond to a minimum of two AEDs. It is believed that early surgical intervention may prevent seizures at a younger age, which, in turn, may improve the intellectual and social status of children. Many types of surgery are available for treatment of refractory epilepsy; one such procedure is known as subpial transection.

OBJECTIVES

To determine the benefits and adverse effects of subpial transection for partial-onset seizures and generalised tonic-clonic seizures in children and adults.

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialised Register (29 June 2015), the Cochrane Central Register of Controlled Trials (CENTRAL; May 2015, Issue 5) and MEDLINE (1946 to 29 June 2015). We imposed no language restrictions.

SELECTION CRITERIA

We considered all randomised and quasi-randomised parallel-group studies, whether blinded or non-blinded.

DATA COLLECTION AND ANALYSIS

Two review authors (BK and SR) independently screened trials identified by the search. The same two review authors planned to independently assess the methodological quality of studies. When studies were identified for inclusion, one review author would have extracted the data, and the other would have verified the data.

MAIN RESULTS

We found no relevant studies.

AUTHORS' CONCLUSIONS

We found no evidence to support or refute use of subpial transection surgery for patients with medically refractory epilepsy. Well-designed randomised controlled trials are needed to guide clinical practice.

Outcome of bipolar electrocoagulation with lesionectomy in the treatment of epilepsy involving eloquent areas

BACKGROUND/AIMS

We have demonstrated previously that bipolar electrocoagulation on functional cortex (BCFC) is a safe and effective approach for epilepsy involving eloquent areas. Here, we report the results of BCFC with lesionectomy for patients with epileptogenic foci partially overlapping eloquent areas.

METHODS

Forty patients who had been treated with lesionectomy with BCFC were retrospectively reviewed with regard to seizure outcome and neurological deficits. Ten similar patients who had received lesionectomy with multiple subpial transections (MST) were examined as a control group.

RESULTS

In the lesionectomy group with BCFC, Engel class I was achieved in 18 (45%) patients, class II in 8 (20%) patients, class III in 8 (20%) patients and class IV in 6 (15%) patients. Five (12.5%) patients developed mild hemiparesis and 1 (2.5%) patient mild sensory dysphasia. In the lesionectomy group with MST, Engel class I was achieved in 3 (30%) patients, class II in 2 (20%) patients, class III in 3 (30%) patients and class IV in 2 (20%) patients. Two (20%) patients developed mild hemiparesis and 1 (10%) patient moderate hemiparesis. All these complications recovered within 1-12 months.

CONCLUSIONS

Compared with MST, the outcome of BCFC with lesionectomy is similar. But since MST leads to mechanical injury, while BCFC causes thermal injury, the complications of BCFC seem less severe.

Cognitive and epilepsy outcomes after epilepsy surgery caused by focal cortical dysplasia in children: early intervention maybe better

BACKGROUND

Focal cortical dysplasia (FCD) is a specific malformation of cortical development harboring intrinsic epileptogenicity, and most of the patients develop drug-resistant epilepsy in early childhood. The detrimental effects of early and frequent seizures on cognitive function in children are significant clinical issues. In this study, we evaluate the effects of early surgical intervention of FCD on epilepsy outcome and cognitive development.

METHODS

From 2006 to 2013, 30 children younger than 18 years old underwent resective surgery for FCDs at Taipei Veterans General Hospital. The mean age at surgery was 10.0 years (range 1.7 to 17.6 years). There were 21 boys and 9 girls. In this retrospective clinical study, seizure outcome, cognitive function, and quality of life were evaluated. To evaluate the effects to outcomes on early interventions, the patients were categorized into four groups according to age of seizure onset, duration of seizure before surgery, and severity of cognitive deficits.

RESULTS

Eleven of 22 (50 %) patients demonstrated developmental delay preoperatively. The Engel seizure outcome achievements were class I in 21 (70 %), class II in 2 (7 %), class III in 6 (20 %), and class IV in 1 (3 %) patients. The locations of FCDs resected were in the frontal lobe in 18 cases, temporal lobe in 7, parietal lobe in 2, and in bilobes including frontoparietal lobe in 2 and parieto-occipital lobes in 1. Eight cases that had FCDs involved in the rolandic cortex presented hemiparesis before surgical resection. Motor function in four of them improved after operation. The histopathological types of FCDs were type Ia in 1, type Ib in 7, type IIa in 7, type IIb in 12, and type III in 3 patients. FCDs were completely resected in 20 patients. Eighteen (90 %) of them were seizure free (p < 0.001) with three patients that received more than one surgery to accomplish complete resection. The patients who had early seizure onset, no significant cognitive function deficit, and early surgical intervention with complete resection in less than 2 years of seizure duration showed best outcomes on seizure control, cognitive function, and quality of life.

CONCLUSION

Delay in cognitive development and poor quality of life is common in children treated for FCDs. Early surgical intervention and complete resection of the lesion help for a better seizure control, cognitive function development, and quality of life. FCDs involved eloquent cortex may not prohibit complete resection for better outcomes.

Surgery for childhood epilepsy

Approximately 60% of all patients with epilepsy suffer from focal epilepsy syndromes. In about 15% of these patients, the seizures are not adequately controlled with antiepileptic drugs; such patients are potential candidates for surgical treatment and the major proportion is in the pediatric group (18 years old or less). Epilepsy surgery in children who have been carefully chosen can result in either seizure freedom or a marked (>90%) reduction in seizures in approximately two-thirds of children with intractable seizures. Advances in structural and functional neuroimaging, neurosurgery, and neuroanaesthesia have improved the outcomes of surgery for children with intractable epilepsy. Early surgery improves the quality of life and cognitive and developmental outcome and allows the child to lead a normal life. Surgically remediable epilepsies should be identified early and include temporal lobe epilepsy with hippocampal sclerosis, lesional temporal and extratemporal epilepsy, hemispherical epilepsy, and gelastic epilepsy with hypothalamic hamartoma. These syndromes have both acquired and congenital etiologies and can be treated by resective or disconnective surgery. Palliative procedures are performed in children with diffuse and multifocal epilepsies who are not candidates for resective surgery. The palliative procedures include corpus callosotomy and vagal nerve stimulation while deep brain stimulation in epilepsy is still under evaluation. For children with "surgically remediable epilepsy," surgery should be offered as a procedure of choice rather than as a treatment of last resort.

Patients with refractory epilepsy treated using a modified multiple subpial transection technique

BACKGROUND

: Multiple subpial transection (MST) is a potential surgical treatment for patients with epileptogenic foci located in cortical areas with higher functions. As neurosurgical teams have become more experienced with MST, the original technique has adapted.

OBJECTIVE

: To report our 6-year experience with a modified MST technique.

METHODS

: The population included 62 consecutive patients with medically refractory epilepsy treated by MST, with a follow-up period ranging from 2 to 9 years. MST was performed on gyri under neuronavigation and guided by intraoperative electrocorticography. We performed radiating MST from a single cortical entry point. The MST technique was described according to the number of transections performed and the Brodmann areas (BAs) involved. Any MST-related complications were registered and followed up. Clinical outcome was described in terms of seizure suppression or reduction according to the Engel modified classification.

RESULTS

: Twelve patients underwent MST alone (MSTa), and 50 had MST with another procedure. The main MST sites were BA 4 (61%) and 3, 1, 2 (58%); in 22% of cases, MST was performed in BA 44, 22, 39, and 40. Permanent neurological deficits were observed in 4 (6.4%) patients; 2 minor deficits were MST related (3.2%). A reduction in the seizure rate of at least 50% was seen in 79% of patients (MSTa group, 75%), and 42% became seizure free (MSTa group, 33%).

CONCLUSION

: This study demonstrates the efficacy and low morbidity of radiating MST performed under neuronavigation and intraoperative electrocorticography.

ABBREVIATIONS

: BA, Brodmann areaEEG, electroencephalogramFDG, 18-fluorodeoxyglucoseioECoG, intraoperative electrocorticographyMRE, medically refractory epilepsyMST, multiple subpial transectionMSTa, multiple subpial transection aloneMST+, multiple subpial transection with other procedures.

A review of traditional and novel treatments for seizures in autism spectrum disorder: findings from a systematic review and expert panel

Despite the fact that seizures are commonly associated with autism spectrum disorder (ASD), the effectiveness of treatments for seizures has not been well studied in individuals with ASD. This manuscript reviews both traditional and novel treatments for seizures associated with ASD. Studies were selected by systematically searching major electronic databases and by a panel of experts that treat ASD individuals. Only a few anti-epileptic drugs (AEDs) have undergone carefully controlled trials in ASD, but these trials examined outcomes other than seizures. Several lines of evidence point to valproate, lamotrigine, and levetiracetam as the most effective and tolerable AEDs for individuals with ASD. Limited evidence supports the use of traditional non-AED treatments, such as the ketogenic and modified Atkins diet, multiple subpial transections, immunomodulation, and neurofeedback treatments. Although specific treatments may be more appropriate for specific genetic and metabolic syndromes associated with ASD and seizures, there are few studies which have documented the effectiveness of treatments for seizures for specific syndromes. Limited evidence supports l-carnitine, multivitamins, and N-acetyl-l-cysteine in mitochondrial disease and dysfunction, folinic acid in cerebral folate abnormalities and early treatment with vigabatrin in tuberous sclerosis complex. Finally, there is limited evidence for a number of novel treatments, particularly magnesium with pyridoxine, omega-3 fatty acids, the gluten-free casein-free diet, and low-frequency repetitive transcranial magnetic simulation. Zinc and l-carnosine are potential novel treatments supported by basic research but not clinical studies. This review demonstrates the wide variety of treatments used to treat seizures in individuals with ASD as well as the striking lack of clinical trials performed to support the use of these treatments. Additional studies concerning these treatments for controlling seizures in individuals with ASD are warranted.

Subpial transection surgery for epilepsy

BACKGROUND

Nearly 30% of patients with epilepsy continue to have seizures in spite of several antiepileptic drug (AED) regimens. In such cases they are regarded as having refractory, or uncontrolled epilepsy.There is no universally accepted definition for uncontrolled or medically refractory epilepsy, but for the purpose of this review, we will consider seizures to be drug resistant if they failed to respond to a minimum of two AEDs. It is believed that early surgical intervention may prevent seizures at a younger age and improve the intellectual and social status of children. There are many types of surgery for refractory epilepsy with subpial transection being one.

OBJECTIVES

Our main aim is to determine the benefits and adverse effects of subpial transection for partial-onset seizures and generalised tonic-clonic seizures in children and adults.

SEARCH METHODS

We searched the Cochrane Epilepsy Group Specialised Register (8 August 2013), The Cochrane Central Register of Controlled Trials (CENTRAL Issue 7 of 12, The Cochrane Library July 2013), and MEDLINE (1946 to 8 August 2013). We did not impose any language restrictions.

SELECTION CRITERIA

We considered all randomised and quasi-randomised parallel group studies either blinded or non-blinded.

DATA COLLECTION AND ANALYSIS

Two review authors (BK and SR) independently screened the trials identified by the search. The same two authors planned to independently assess the methodological quality of studies. If studies had been identified for inclusion, one author would have extracted the data and the other would have verified it.

MAIN RESULTS

No relevant studies were found.

AUTHORS' CONCLUSIONS

There is no evidence to support or refute the use of subpial transection surgery for medically refractory cases of epilepsy. Well designed randomised controlled trials are needed in future to guide clinical practice.

Critical review of palliative surgical techniques for intractable epilepsy

Approximately one third of epilepsy patients are not adequately treatable by antiepileptic medication. Curative resective epilepsy surgery can be performed in only a subgroup of these pharmacoresistent patients in whom the epileptogenic focus is localizable and does not overlap with eloquent brain areas. To the remaining patients (with bilateral or multiple epileptogenic foci, with epilepsy onset in eloquent areas, or with no identifiable epileptogenic focus) palliative epilepsy surgery can be offered if they suffer from disabling seizures. Standard palliative procedures currently comprise corpus callosotomy, multiple subpial transections, and vagus nerve stimulation. New approaches such as focus distant deep brain stimulation or direct stimulation of the hippocampus have gained the most interest. Feasibility studies, small pilot studies, and, recently, larger multicenter trials showed that direct brain stimulation shall be considered a potential helpful procedure in the field of palliative surgery. Moreover, with the increasing use of stereo-EEG in invasive video-EEG monitoring, stereo-EEG-guided thermocoagulation has the potential for a promising new treatment option in patients not amenable to resective epilepsy surgery. There is no general consensus on which palliative procedure is most effective in patients with difficult-to-treat epilepsy syndromes. The decision must be based on individual factors of a given patient. This review summarizes experience with palliative approaches collected in adult and pediatric patient series over the past decades and may help to thoroughly balance beneficial effects and risks of each procedure.

Non-resective surgery and radiosurgery for treatment of drug-resistant epilepsy

Epilepsy surgery is an effective treatment for properly selected patients with intractable seizures. However, many patients with medically intractable epilepsy are not excellent candidates for surgical resection of the epileptogenic zone. Due to recent advances in computer technology and bioengineering, several novel techniques are receiving increasing interest for their role in the care of people with epilepsy. Neuromodulation is an emerging surgical option to be used when conventional resective surgery is not indicated. We review the indications and expected outcomes of neuromodulatory treatments currently available for the treatment of refractory epilepsy, i.e., vagus nerve stimulation, deep brain stimulation, stereotactic radiosurgery, and multiple subpial transections.

Pure bipolar electro-coagulation on functional cortex in the treatment of epilepsy involving eloquent areas

PURPOSE

Although resection of an epileptogenic region remains the main procedure of epilepsy surgery, epileptogenic areas in functionally critical cortex cannot be approached in that manner. Bipolar electro-coagulation on functional cortex (BCFC) was developed to treat such refractory seizures without causing unacceptable neurological deficits. Here we report the outcome of this therapy.

METHODS

Fifteen patients who underwent pure BCFC without resection between 2002 and 2008 were retrospectively reviewed with regard to seizure outcome, postoperative complications, and predictive factors.

KEY FINDINGS

Seven patients developed hemiparesis after the operation but fully recovered within 1-6 months. One patient developed mild dysphasia, which was resolved within 12 months. All neurological deficits were temporary in the sense that they ultimately did not result in a deficit that would be noticed during a standard clinical examination. There were no subdural hemorrhage and infection. Engel class I outcome was achieved in two (13.3%) patients; class II, in six (40%); class III, in three (20%); and class IV, in four (26.7%).

SIGNIFICANCE

The BCFC technique is only a palliative surgery, and cannot be applied for all epilepsies, however, this therapy proved to be effective when the epileptogenic foci are located in unresectable cortex. BCFC is safe and easy to use.

Extratemporal, nonlesional epilepsy in children: postsurgical clinical and neurocognitive outcomes

OBJECT

Patients undergoing epilepsy surgery without evidence of a lesion on MR imaging and without a temporal source for seizure onset generally have less favorable outcomes than patients with structural lesions or temporal onset. However, many of these patients are viable candidates for invasive monitoring and subsequent resection or multiple subpial transections (MSTs). The purpose of this study was to evaluate the surgical treatment of pediatric patients with extratemporal, nonlesional epilepsy in order to better understand the clinical and neuropsychological outcomes expected in this patient group.

METHODS

Forty-three pediatric patients with negative results on MR imaging and lateralized, extratemporal findings on electroencephalography underwent invasive monitoring with grid and/or strip electrodes. Thirty-three subsequently had resection of an epileptogenic focus and/or MSTs.

RESULTS

Outcome was classified as Engel class I or II in 54.5% of the patients who underwent resection/MSTs and Engel class III or IV in 45.5%. Use of MSTs was associated with poor outcome. Neuropsychological evaluation showed significant improvement in immediate auditory attention following surgery and revealed several significant results on subgroup analysis. Complications occurred in 14% of patients (a 7% rate per procedure). Ten patients (23%) underwent invasive monitoring without proceeding to therapeutic surgery because no epileptogenic region was amenable to resection. Neuropsychological outcomes were generally stable.

CONCLUSIONS

Patients with extratemporal, nonlesional seizures are viable candidates for invasive monitoring with grid/strip electrodes, and good outcomes can be obtained with resective surgery. The use of MSTs may correlate with worse outcome. This study also provides additional data to assist in counseling patients on the risks of negative invasive monitoring, deficits resulting from resection/MSTs, and possible operative complications.

Surgery for perirolandic epilepsy: Epileptogenic cortex resection guided by chronic intracranial electroencephalography and electric cortical stimulation mapping

SUBJECT

The objective of this study was to assess outcome with regard to seizure status and neurological function in patients undergoing resective surgery involving the perirolandic area.

METHOD

All 15 patients who underwent perirolandic cortical resection between October 2006 and September 2007 at the Comprehensive Epilepsy Centre of Beijing Xuanwu Hospital were included in the study. The locations of functional cortical areas, ictal onset zones and epileptogenic lesions were mapped by chronic intracranial EEG recordings and electric cortical stimulation. Seizure outcome was determined using the modified classification of Engel and colleagues. Motor and sensory deficits were monitored.

RESULTS

At last follow-up 5 patients (33%) were in Engel class I, 4 (27%) were in class II, 3 (20%) were in class III, and 3 (20%) were in class IV. Nine patients suffered immediate functional deficits; 8 of these recovered completely within 2 weeks to 3 months of surgery. One had mild persistent loss of finger motor control.

CONCLUSION

After accurate presurgical evaluation using invasive recordings and functional brain mapping, epileptogenic cortical resection can give excellent results and few deficits in patients with perirolandic epilepsy.

Neurosurgical management of intractable rolandic epilepsy in children: role of resection in eloquent cortex. Clinical article

OBJECT

The authors undertook this study to review their experience with cortical resections in the rolandic region in children with intractable epilepsy.

METHODS

The authors retrospectively reviewed the medical records obtained in 22 children with intractable epilepsy arising from the rolandic region. All patients underwent preoperative electroencephalography (EEG), MR imaging, prolonged video-EEG recordings, functional MR imaging, magnetoencephalography, and in some instances PET/SPECT studies. In 21 patients invasive subdural grid and depth electrode monitoring was performed. Resection of the epileptogenic zones in the rolandic region was undertaken in all cases. Seizure outcome was graded according to the Engel classification. Functional outcome was determined using validated outcome scores.

RESULTS

There were 10 girls and 12 boys, whose mean age at seizure onset was 3.2 years. The mean age at surgery was 10 years. Seizure duration prior to surgery was a mean of 7.4 years. Nine patients had preoperative hemiparesis. Neuropsychological testing revealed impairment in some domains in 19 patients in whom evaluation was possible. Magnetic resonance imaging abnormalities were identified in 19 patients. Magnetoencephalography was performed in all patients and showed perirolandic spike clusters on the affected side in 20 patients. The mean duration of invasive monitoring was 4.2 days. The mean number of seizures during the period of invasive monitoring was 17. All patients underwent resection that involved primary motor and/or sensory cortex. The most common pathological entity encountered was cortical dysplasia, in 13 children. Immediately postoperatively, 20 patients had differing degrees of hemiparesis, from mild to severe. The hemiparesis improved in all affected patients by 3-6 months postoperatively. With a mean follow-up of 4.1 years (minimum 2 years), seizure outcome in 14 children (64%) was Engel Class I and seizure outcome in 4 (18%) was Engel Class II. In this series, seizure outcome following perirolandic resection was intimately related to the child's age at the time of surgery. By univariate logistic regression analysis, age at surgery was a statistically significant factor predicting seizure outcome (p < 0.024).

CONCLUSIONS

Resection of rolandic cortex for intractable epilepsy is possible with expected morbidity. Accurate mapping of regions of functional cortex and epileptogenic zones may lead to improved seizure outcome in children with intractable rolandic epilepsy. It is important to counsel patients and families preoperatively to prepare them for possible worsened functional outcome involving motor, sensory and/or language pathways.

Surgical treatment of parietal lobe epilepsy

Object

Parietal lobe epilepsy (PLE) accounts for a small percentage of extratemporal epilepsies, and only a few and mostly smaller series have been reported. Preoperative findings, surgical strategies, pathological bases, and postoperative outcomes for PLE remain to be elucidated.

Methods

Patients with PLE were identified by screening a prospective epilepsy surgery database established in 1989 at the University of Bonn. Charts, preoperative imaging studies, surgical reports, and neuropathological findings were reviewed. Seizure outcome was classified according to Engel class (I–IV).

Results

Forty patients (23 females and 17 males) with PLE were identified and had a mean age of 25.0 years and a mean preoperative epilepsy duration of 13.7 years. Nine patients had a significant medical history (for example, trauma, meningitis/encephalitis, or perinatal hypoxia). Preoperative MR imaging abnormalities were identified in 38 (95%) of 40 patients; 26 patients (65%) underwent invasive electroencephalography evaluation. After lesionectomy of the dominant (in 20 patients) or nondominant (in 20 patients) parietal lobe and additional multiple subpial transections (in 11 patients), 2 patients suffered from surgical and 12 from neurological complications, including temporary partial Gerstmann syndrome. There were no deaths. Histopathological analysis revealed 16 low-grade tumors, 11 cortical dysplasias, 9 gliotic scars, 2 cavernous vascular malformations, and 1 granulomatous inflammation. In 1 case, no histopathological diagnosis could be made. After a mean follow-up of 45 months, 27 patients (67.5%) became seizure free or had rare seizures (57.5% Engel Class I; 10% Engel Class II; 27.5% Engel Class III; and 5% Engel Class IV).

Conclusions

Parietal lobe epilepsy is an infrequent cause of extratemporal epilepsy. Satisfactory results (Engel Classes I and II) were obtained in 67.5% of patients in our series. A temporary partial hemisensory or Gerstmann syndrome occurs in a significant number of patients.

The surgery of epilepsy

The idea of surgical treatment for epilepsy is not new. However, widespread use and general acceptance of this treatment has only been achieved during the past three decades. A crucial step in this direction was the development of video electroencephalographic monitoring. Improvements in imaging resulted in an increased ability for preoperative identification of intracerebral and potentially epileptogenic lesions. High resolution magnetic resonance imaging plays a major role in structural and functional imaging; other functional imaging techniques (e.g., positron emission tomography and single-photon emission computed tomography) provide complementary data and, together with corresponding electroencephalographic findings, result in a hypothesis of the epileptogenic lesion, epileptogenic zone, and the functional deficit zone. The development of microneurosurgical techniques was a prerequisite for the general acceptance of elective intracranial surgery. New less invasive and safer resection techniques have been developed, and new palliative and augmentative techniques have been introduced. Today, epilepsy surgery is more effective and conveys a better seizure control rate. It has become safer and less invasive, with lower morbidity and mortality rates. This article summarizes the various developments of the past three decades and describes the present tools for presurgical evaluation and surgical strategy, as well as ideas and future perspectives for epilepsy surgery.

Surgical treatment of intractable epilepsy associated with focal cortical dysplasia

Focal cortical dysplasias (FCDs) are congenital malformations of cortical development that are a frequent cause of refractory epilepsy in both children and adults. With advances in structural and functional neuroimaging, these lesions are increasingly being identified as a cause of intractable epilepsy in patients undergoing surgical management for intractable epilepsy. Comprehensive histological classification of FCDs with the establishment of uniform terminology and reproducible pathological features has aided in our understanding of FCDs as an epilepsy substrate. Complete resection of FCDs and the associated epileptogenic zone can result in a good surgical outcome in the majority of patients.

Computer modelling of epilepsy

Epilepsy is a complex set of disorders that can involve many areas of the cortex, as well as underlying deep-brain systems. The myriad manifestations of seizures, which can be as varied as déjà vu and olfactory hallucination, can therefore give researchers insights into regional functions and relations. Epilepsy is also complex genetically and pathophysiologically: it involves microscopic (on the scale of ion channels and synaptic proteins), macroscopic (on the scale of brain trauma and rewiring) and intermediate changes in a complex interplay of causality. It has long been recognized that computer modelling will be required to disentangle causality, to better understand seizure spread and to understand and eventually predict treatment efficacy. Over the past few years, substantial progress has been made in modelling epilepsy at levels ranging from the molecular to the socioeconomic. We review these efforts and connect them to the medical goals of understanding and treating the disorder.

Surgical treatment of occipital lobe epilepsy

OBJECT

Occipital lobe epilepsy (OLE) accounts for a small percentage of extratemporal epilepsies and only few and mostly small patient series have been reported. Preoperative findings, surgical strategies, histopathological bases, and postoperative outcomes for OLE remain to be elucidated.

METHODS

A group of 54 patients with occipital lobe involvement were identified from a prospective epilepsy surgery database established in 1989. Medical charts, surgical reports, MR imaging, and histopathology data were reviewed, and patients with additional temporal and/or parietal involvement were categorized separately. Seizure outcome was classified according to the Engel classification scheme (Classes I-IV). Two patients were excluded due to incomplete data sets. Fifty-two patients with intractable epilepsy involving predominantly the occipital lobe were included in the study, comprising 17.8% of 292 patients undergoing operations for extratemporal epilepsies.

RESULTS

In nearly all cases (50 [96.2%] of 52), a structural lesion was visible on preoperative MR imaging. Of these cases, 29 (55.8%) had "pure" OLE with no temporal or parietal lobe involvement. Most patients (83%) had complex partial seizures, and 60% also had generalized seizures. All patients underwent occipital lesionectomies or topectomies; 9 patients (17.3%) underwent additional multiple subpial transections. Histopathology results revealed 9 cortical dysplasias (17.3%), 9 gangliogliomas (17.3%), 6 other tumors (11.5%), 13 vascular malformations (25%), and 15 glial scars (28.8%). Visual field deficits were present in 36.4% of patients preoperatively, and 42.4% had new or aggravated visual field deficits after surgery. After a mean follow-up of 80 months, 36 patients were seizure free (69.2% Engel Class I), 4 rarely had seizures (7.7% Engel Class II), 8 improved more than 75% (15.4% Engel Class III), and 4 had no significant improvement (7.7% Engel Class IV). Multifactorial logistic regression analysis revealed that early age at epilepsy manifestation (p = 0.031) and shorter epilepsy duration (p = 0.004) were predictive of better seizure control. All other clinical and surgical factors were not significant in predicting outcome.

CONCLUSIONS

Occipital lobe epilepsy is an infrequent but significant cause of extratemporal epilepsy. Satisfactory results (Engel Class I or II) were obtained in 77% of patients in our series. Postoperative visual field deficits occurred in a significant proportion of patients. In the modern MR imaging era, lesions should be investigated in patients with OLE and lesionectomies should be performed early for a better outcome.

[Surgical resections in functional areas: report of 89 cases]

Surgical resections for intractable epilepsy are generally associated with a high risk of permanent neurological deficit and a poor rate of seizure control. We present a series of 89 patients operated on from 1992 through 2007 for drug-resistant partial epilepsy, in whom surgery was performed in a functional area of the brain: the central (sensorimotor and supplementary motor areas) region in 48 cases, posterior regions (parietal and occipital) in 27, the insula in eight, and the language areas in six. Epilepsy was cryptogenic in 12 patients, and lesion-related in 77: malformation of cortical development in 43, tumor in 17, perinatal cicatrix in 13, vascular lesion in three, and another prenatal lesion in one. Seventy patients underwent stereoelectroencephalographic (SEEG) exploration. The surgical procedure was resective (lesionectomy or SEEG-guided corticectomy) in 83 patients and multiple stereotactic thermocoagulations in six. Ten patients were reoperated because of early seizure recurrence. A postoperative complication was observed in 12 patients. Postoperative deficits were observed in 54 patients (61%) and resolved completely in 29. In 25, a permanent deficit persisted, minor in 19 and moderate to severe in six, which did not correlate with localization or etiology. With a one-year follow-up in 74 patients (mean, 3.6 years), 53 (72%) were in Engel's class I, including 38 (51%) in class IA. Seizure outcome was significantly associated with etiology: 93% of Taylor-type focal cortical dysplasia, whereas only 40% of cryptogenic epilepsies were in class I (p<0.05). This suggests that resective or disconnective surgery for intractable partial epilepsy in functional areas of the brain may be followed by excellent results on seizures and a moderate risk of permanent neurological sequelae.

Pre-surgical evaluation and surgical treatment in children with extratemporal epilepsy

INTRODUCTION

This review summarizes some patterns of pre-surgical evaluation and surgical treatment of extratemporal epilepsy in pediatric patients with medically refractory seizures, whose ictal behavior is variable. The most effective treatment for intractable partial epilepsy is a focal cortical resection with excision of the epileptogenic zone (the area of ictal onset and initial seizure propagation). This might be risky, though, in the case of a widespread lesion, sometimes encroaching one or more lobes, given the risk to the functional cerebral cortex. An anterior temporal lobectomy might prove more effective then in preventing seizures with fewer potential complications. If partial extratemporal epilepsy is associated with pharmaco-resistant seizures, the preoperative evaluation and operative strategy are determined according to the epileptogenic zone and to the relationship between a substrate-directed disorder and eloquent areas. The pediatric treatment of extratemporal epilepsy is aimed at controlling the seizures, avoiding morbidity, and improving the patient's quality of life through psychosocial integration. Since the immature brain is more plastic than when mature, the recovery of functions after surgery is greater in children than in adults.

RECOMMENDATION

Early surgery is recommended for children with intractable epilepsy, and is now accepted as an important therapeutic modality also for children with chronic epilepsy.

CONCLUSION

Technological advances in the last two decades, mainly in neuroimaging, have led many medical centers to consider surgical treatment of epilepsy, accuracy being granted by MRI-based neuronavigation systems-an interface between the lesion seen in the preoperative magnetic resonance imaging (MRI) and the operative field, often invisible to the surgeon.

Multiple subpial transections in pediatric epilepsy: indications and outcomes

OBJECTIVE

Multiple subpial transection (MST) is a surgical technique mainly used when epileptiform activity arises from eloquent or functional brain cortex. In the medical literature, there are relatively few studies reporting the efficacy and safety of this procedure in adults and in children. We review the scientific rationale, the indications, and the results of this procedure.

METHODS

Neuroanatomic studies show that the basic functional cortical unit is arranged vertically, and epileptic activity spreads horizontally. Minimal cortical unit is essential for maintenance of cortical activity. Vertical incisions in the cortex interrupt transverse synaptic connections, preventing seizure propagation while preserving the vertical column subserving neuronal function. In the past, it has been difficult to assess the efficacy of MSTs per se, as they have usually been performed together with cortical resection or lesionectomy. After MSTs, studies show that 33-46% of treated children are in Engel class I or II. The permanent complication rate is low with no permanent language or motor disabilities.

CONCLUSIONS

MST is a safe procedure with unclear specific efficacy. It has been used mainly in conjunction with cortical resection or lesionectomy, when the eloquent cortex is involved in the seizure activity. Further prospective studies are needed to define the role of MST in epilepsy surgery.

Long-term seizure outcomes following epilepsy surgery: a systematic review and meta-analysis

Assessment of long-term outcomes is essential in brain surgery for epilepsy, which is an irreversible intervention for a chronic condition. Excellent short-term results of resective epilepsy surgery have been established, but less is known about long-term outcomes. We performed a systematic review and meta-analysis of the evidence on this topic. To provide evidence-based estimates of long-term results of various types of epilepsy surgery and to identify sources of variation in results of published studies, we searched Medline, Index Medicus, the Cochrane database, bibliographies of reviews, original articles and book chapters to identify articles published since 1991 that contained > or =20 patients of any age, undergoing resective or non-resective epilepsy surgery, and followed for a mean/median of > or =5 years. Two reviewers independently assessed study eligibility and extracted data, resolving disagreements through discussion. Seventy-six articles fulfilled our eligibility criteria, of which 71 reported on resective surgery (93%) and five (7%) on non-resective surgery. There were no randomized trials and only six studies had a control group. Some articles contributed more than one study, yielding 83 studies of which 78 dealt with resective surgery and five with non-resective surgery. Forty studies (51%) of resective surgery referred to temporal lobe surgery, 25 (32%) to grouped temporal and extratemporal surgery, seven (9%) to frontal surgery, two (3%) to grouped extratemporal surgery, two (3%) to hemispherectomy, and one (1%) each to parietal and occipital surgery. In the non-resective category, three studies reported outcomes after callosotomy and two after multiple subpial transections. The median proportion of long-term seizure-free patients was 66% with temporal lobe resections, 46% with occipital and parietal resections, and 27% with frontal lobe resections. In the long term, only 35% of patients with callosotomy were free of most disabling seizures, and 16% with multiple subpial transections remained free of all seizures. The year of operation, duration of follow-up and outcome classification system were most strongly associated with outcomes. Almost all long-term outcome studies describe patient cohorts without controls. Although there is substantial variation in outcome definition and methodology among the studies, consistent patterns of results emerge for various surgical interventions after adjusting for sources of heterogeneity. The long-term (> or =5 years) seizure free rate following temporal lobe resective surgery was similar to that reported in short-term controlled studies. On the other hand, long-term seizure freedom was consistently lower after extratemporal surgery and palliative procedures.