Comparison of magnetic resonance-guided laser interstitial thermal therapy corpus callosum ablation to open microsurgical corpus callosotomy: A single-center retrospective cohort study

OBJECTIVE

Corpus callosotomy (CC) is an important treatment for atonic seizures in patients with generalized or multifocal drug-resistant epilepsy (DRE). Traditionally, CC is performed via an open microsurgical approach, but more recently, MR-guided stereotactic laser interstitial thermal therapy (LITT) corpus callosum ablation (CCA) has been developed to leverage the safety and minimally invasive nature of LITT. Given the recent adoption of CCA at select centers, how CCA compares to CC is unknown. We aim to compare the clinical seizure outcomes of CCA and CC after extended follow-up.

METHODS

We performed a retrospective cohort study to compare the effectiveness and safety of CC to CCA from 1994 to 2022. The primary outcome was a 50% reduction in target seizure. Secondary outcome measures were postoperative length of stay, adverse events, and other effectiveness metrics. Comparative statistics were executed using Stata. Normality for continuous variables was assessed, and parametric statistics were utilized as needed. Frequency was compared with chi-squared or Fischer's exact tests, when applicable.

RESULTS

Data from 47 operations performed on 36 patients were included in this study, of which 13 (36%) patients underwent 17 CCA. Patients who received CCA had similar rates of meaningful reduction (>50%) of atonic seizures as their CC counterparts (55% vs 70% P = 0.15). Patients undergoing CCA had significantly shorter hospitalizations than those receiving CC (2.5 vs 6.0 days P < 0.001). There was no significant difference in rates of postoperative complications between the groups, although the magnitude of the complication rates was lower in the CCA cohort (12% vs 28%).

SIGNIFICANCE

This early experience suggests CCA has similar outcomes to traditional CC, albeit with a shorter hospital stay. However, future studies are necessary to investigate the noninferiority between these two approaches. Large multicenter studies are necessary to investigate differences in adverse events and whether these findings generalize across other centers.

A multi-center comparison of surgical techniques for corpus Callosotomy in pediatric drug-resistant epilepsy

OBJECTIVES

Corpus callosotomy (CC) is used to reduce seizures, primarily in patients with generalized drug-resistant epilepsy (DRE). The invasive nature of the procedure contributes to underutilization despite its potential superiority to other palliative procedures. The goal of this study was to use a multi-institutional epilepsy surgery database to characterize the use of CC across participating centers.

METHODS

Data were acquired from the Pediatric Epilepsy Research Consortium (PERC) Surgery Database, a prospective observational study collecting data on children 0-18 years referred for surgical evaluation of DRE across 22 U.S. pediatric epilepsy centers. Patient, epilepsy, and surgical characteristics were collected across multiple CC modalities. Outcomes and complications were recorded and analyzed statistically.

RESULTS

Eighty-three patients undergoing 85 CC procedures at 14 participating epilepsy centers met inclusion criteria. Mean age at seizure onset was 2.3 years (0-9.4); mean age for Phase I evaluation and surgical intervention were 9.45 (.1-20) and 10.46 (.2-20.6) years, respectively. Generalized seizure types were the most common (59%). Complete CC was performed in 88%. The majority of CC procedures (57%) were via open craniotomy, followed by laser interstitial thermal therapy (LiTT) (20%) and mini-craniotomy/endoscopic (mc/e) (22%). Mean operative times were significantly longer for LiTT, whereas mean estimated blood loss was greater in open cases. Complications occurred in 11 cases (13%) and differed significantly between surgical techniques (p < .001). There was no statistically significant difference in length of postoperative stay across approaches. Mean follow-up was 12.8 months (range 1-39). Favorable Engel outcomes were experienced by 37 (78.7%) of the patients who underwent craniotomy, 10 (58.8%) with LiTT, and 12 (63.2%) with mc/e; these differences were not statistically significant.

SIGNIFICANCE

CC is an effective surgical modality for children with DRE. Regardless of surgical modality, complication rates are acceptable and seizure outcomes generally favorable. Newer, less-invasive, surgical approaches may lead to increased adoption of this efficacious therapeutic option for pediatric DRE.

Applying the en-bloc technique in corpus callosum glioblastoma surgery contributes to maximal resection and better prognosis: a retrospective study

BACKGROUND

Corpus callosum glioblastoma (ccGBM) is a specific type of GBM and has worse outcomes than other non-ccGBMs. We sought to identify whether en-bloc resection of ccGBMs based on T2-FLAIR imaging contributes to clinical outcomes and can achieve a satisfactory balance between maximal resection and preservation of neurological function.

METHODS

A total of 106 adult ccGBM patients (including astrocytoma, WHO grade 4, IDH mutation, and glioblastoma) were obtained from the Department of Neurosurgery in Nanfang Hospital between January 2008 and December 2018. The clinical data, including gender, age, symptoms, location of tumor, involvement of eloquent areas, extent of resection (EOR), pre- and postoperative Karnofsky Performance Status (KPS) scales, and National Institute of Health stroke scale (NIHSS) scores were collected. Propensity score matching (PSM) analysis was applied to control the confounders for analyzing the relationship between the en-bloc technique and EOR, and the change in the postoperative KPS scales and NIHSS scores.

RESULTS

Applying the en-bloc technique did not negatively affect the postoperative KPS scales compared to no-en-bloc resection (P = 0.851 for PSM analysis) but had a positive effect on preserving or improving the postoperative NIHSS scores (P = 0.004 for PSM analysis). A positive correlation between EOR and the en-bloc technique was identified (r = 0.483, P < 0.001; r = 0.720, P < 0.001 for PSM analysis), indicating that applying the en-bloc technique could contribute to enlarged maximal resection. Further survival analysis confirmed that applying the en-bloc technique and achieving supramaximal resection could significantly prolong OS and PFS, and multivariate analysis suggested that tumor location, pathology, EOR and the en-bloc technique could be regarded as independent prognostic indicators for OS in patients with ccGBMs, and pathology, EOR and the en-bloc technique were independently correlated with patient's PFS. Interestingly, the en-bloc technique also provided a marked reduction in the risk of tumor recurrence compared with the no-en-bloc technique in tumors undergoing TR, indicating that the essential role of the en-bloc technique in ccGBM surgery (HR: 0.712; 95% CI: 0.535-0.947; P = 0.02).

CONCLUSIONS

The en-bloc technique could contribute to achieving an enlarged maximal resection and could significantly prolong overall survival and progression-free survival in patients with ccGBMs.

Clinical outcomes of MR-guided laser interstitial thermal therapy corpus callosum ablation in drug-resistant epilepsy: a systematic review and meta-analysis

OBJECTIVE

The goal of this systematic review and meta-analysis was to provide an updated analysis of studies investigating outcomes, morbidity, and mortality associated with MR-guided laser interstitial thermal therapy (MRgLITT) corpus callosum ablation (CCA).

METHODS

Study inclusion criteria for screening required that studies report on human subjects only, including patients aged 1-52 years diagnosed with drug-resistant epilepsy who underwent CCA. Sixteen articles published between 2016 and 2023 were included for the systematic review and analysis, including 4 case reports, 11 case series, and 1 case-control study. Altogether, 85 pediatric and adult patients undergoing CCA were included in the systematic review (46 patients younger and 39 patients older than 21 years). The main outcome of seizure freedom was measured using the decrease in the frequency of atonic seizures following surgery, percentage of atonic seizure freedom following surgery, and percentage of overall seizure freedom following surgery. These measurements were made using data from the last follow-up for patients with at least 6 months of follow-up post-CCA.

RESULTS

The extent of CCA differed across the pooled cohorts, including anterior two-thirds CCA (38.89%, n = 35) and posterior one-third CCA for completion of a prior partial CCA (22.22%, n = 20), complete CCA (27.78%, n = 25), or CCA of residual white matter in the case of subtotal initial ablation (5.56%, n = 5). Overall, 12.94% of the patients undergoing CCA experienced operational complications. The most common operative complications across 90 CCA operations were probe malpositioning (n = 6), hemorrhage (n = 5), off-target extension of splenium ablation to the thalamus (n = 1), infection (n = 1), and postoperative CSF leak (n = 1). Neurological deficits following CCA were reported as transient in 18.82% and permanent in 4.71% of patients across all studies. The most common neurological deficits were disconnection syndrome (n = 4) or transient hemiplegia (supplementary motor area-like syndrome; n = 4). The 6-month overall seizure freedom rate was 18.87% of 53 patients, and the atonic seizure freedom rate was 46.28% of 52 patients postoperatively. CCA resulted in an average decrease in atonic seizure rate from 8.30 to 1.65 atonic seizures per day (average decrease 80.12%).

CONCLUSIONS

CCA is associated with an acceptable complication profile, and most patients experience a meaningful reduction in target seizure semiologies. Accurate MRgLITT probe placement is likely important for maximizing CCA while avoiding collateral damage. Avoidable complications of CCA include off-target ablation (and associated deficits), hemorrhage, and future surgery for residual CCA to palliate continued seizures.

Added value of corpus callosotomy following vagus nerve stimulation in children with Lennox-Gastaut syndrome: A multicenter, multinational study

OBJECTIVE

Lennox-Gastaut syndrome (LGS) is a severe form of epileptic encephalopathy, presenting during the first years of life, and is very resistant to treatment. Once medical therapy has failed, palliative surgeries such as vagus nerve stimulation (VNS) or corpus callosotomy (CC) are considered. Although CC is more effective than VNS as the primary neurosurgical treatment for LGS-associated drop attacks, there are limited data regarding the added value of CC following VNS. This study aimed to assess the effectiveness of CC preceded by VNS.

METHODS

This multinational, multicenter retrospective study focuses on LGS children who underwent CC before the age of 18 years, following prior VNS, which failed to achieve satisfactory seizure control. Collected data included epilepsy characteristics, surgical details, epilepsy outcomes, and complications. The primary outcome of this study was a 50% reduction in drop attacks.

RESULTS

A total of 127 cases were reviewed (80 males). The median age at epilepsy onset was 6 months (interquartile range [IQR] = 3.12-22.75). The median age at VNS surgery was 7 years (IQR = 4-10), and CC was performed at a median age of 11 years (IQR = 8.76-15). The dominant seizure type was drop attacks (tonic or atonic) in 102 patients. Eighty-six patients underwent a single-stage complete CC, and 41 an anterior callosotomy. Ten patients who did not initially have a complete CC underwent a second surgery for completion of CC due to seizure persistence. Overall, there was at least a 50% reduction in drop attacks and other seizures in 83% and 60%, respectively. Permanent morbidity occurred in 1.5%, with no mortality.

SIGNIFICANCE

CC is vital in seizure control in children with LGS in whom VNS has failed. Surgical risks are low. A complete CC has a tendency toward better effectiveness than anterior CC for some seizure types.

Interhemispheric Integration after Callosotomy: A Meta-Analysis of Poffenberger and Redundant-Target Paradigms

The central role of the corpus callosum in integrating perception and cognition across the cerebral hemispheres makes it highly desirable for clinical and basic research to have a repertoire of experimental paradigms assessing callosal functioning. Here, the objective was to assess the validity of two such paradigms (Poffenberger, redundant-target paradigms) by conducting single-step meta-analyses on individual case data of callosotomy patients. Studies were identified by systematic literature search (source: Pubmed and WebOfKnowledge, date: 07.03.2022) and all studies were included that reported callosotomy case data for either paradigm. Twenty-two studies (38 unique cases) provided 116 observations of the crossed-uncrossed difference (CUD) for the Poffenberger paradigm, while ten studies (22 cases, 103 observations) provided bilateral redundancy gain (bRG) measures. Using linear-mixed models with "individual" and "experiment" as random-effects variable, the mean CUD was estimated at 60.6 ms (CI95%: 45.3; 75.9) for commissurotomy, 43.5 ms (26.7; 60.2) for complete callosotomy, and 8.8 ms (1.1; 16.6) for partial anterior-medial callosotomy patients. The estimates of commissurotomy/callosotomy patients differed significantly from patients with partial callosotomy and healthy controls. The mean bRGmin (minimum unilateral reference) was estimated at 42.8 ms (27.1;58.4) for patients with complete and 30.8 ms (16.8; 44.7) for patients with partial callosotomy, both differing significantly from controls. One limitation was that different formulas for bRG were used, making it necessary to split the sample and reducing test power of some analyses. Nevertheless, the present findings suggest that both paradigms assess interhemispheric callosal integration, confirming their construct validity, but likely test distinct callosal functions.

Influence of extent and age at corpus callosotomy on seizure outcomes. A single center experience

Corpus callosotomy (CC) is a palliative treatment for drop seizures in patients with drug-resistant nonlocalizable epilepsy. We compared drop seizure outcomes between patients undergoing anterior CC versus complete CC and examined factors impacting outcomes for drop seizures including age at CC and duration of epilepsy. A retrospective review of patients who underwent CC between 2003 and 2022 with a minimum of 6 months postsurgical follow-up was included. Outcome measure for drop seizures included seizure reduction ≥50% from baseline as well as elimination of drop seizures. Thirty-eight patients were included. Overall, ≥50% reduction in drop seizures occurred in nearly 70% (23 out of 33) patients with complete elimination in 58% (19 out of 33). Compared with anterior CC (n = 13), patients undergoing complete CC (n = 25) had increased likelihood of ≥50% reduction (p = 0.006) or elimination (p = 0.024) of drop seizures. Regression analysis showed that complete CC was the primary predictor for improved drop seizure outcomes (elimination, p = 0.014 or ≥50% reduction, p = 0.006), while age at CC and duration of epilepsy did not impact the outcomes. Compared to anterior CC, complete CC was significantly more likely to lead to improvement/freedom from drop seizures. Age at CC or duration of epilepsy did not influence drop seizure outcomes.

Palliation for catastrophic nonlocalizing epilepsy: a retrospective case series of complete corpus callosotomy at a single institution

OBJECTIVE

In this study, the authors describe their 10-year single-institution experience with single-step complete corpus callosotomy (CCC) for seizure management in pediatric and adult patients with catastrophic, medically refractory, nonlocalizing epilepsy at Advent Health Orlando.

METHODS

The authors conducted a retrospective observational study of patients aged 6 months to 49 years who underwent clinically indicated CCC for drug-resistant nonlocalizing epilepsy at Advent Health Orlando between July 2011 and July 2021. Follow-up ranged from 12 months to 10 years.

RESULTS

Of the 101 patients (57% of whom were male) who met eligibility criteria, 81 were pediatric patients and 20 were ≥ 18 years. All patients had seizures that appeared poorly lateralized on both electroencephalograms and clinical semiological studies. Of 54 patients with drop seizures before CCC, 29 (54%) achieved stable freedom from drop seizures after CCC. Of the 101 patients, 14 (13.9%) experienced stable resolution of all types of clinical seizures (International League Against Epilepsy classes 1 and 2). The most common postoperative neurological complication was a transient disconnection syndrome, observed in 50% of patients; of those patients, 73% experienced syndrome resolution within 2 months after surgery, and all resolved by the 2-year follow-up. Formal neuropsychological test results were stable in 13 patients assessed after CCC.

CONCLUSIONS

CCC is an effective and well-tolerated palliative surgical technique. In this study, drop attacks were reduced after CCC but could recur for the first time as late as 44 months after surgery. Other seizure types were also reduced postoperatively but could recur for the first time as late as 28 months after surgery. Nearly 14% of patients achieved stable and complete freedom from seizures after CCC. Re-evaluation after CCC can reveal lateralized seizure onset in some patients.

Anatomical step-by-step dissection of common approaches to the third ventricle for trainees: surgical anatomy of the anterior transcortical and interhemispheric transcallosal approaches, surgical principles, and illustrative pediatric cases

PURPOSE

To create a high-quality, cadaver-based, operatively oriented resource documenting the anterior transcortical and interhemispheric transcallosal approaches as corridors to the third ventricle targeted towards neurosurgical trainees at all levels.

METHODS

Two formalin-fixed, latex-injected specimens were dissected under microscopic magnification and endoscopic-assisted visualization. Dissections of the transcortical and transcallosal craniotomies with transforaminal, transchoroidal, and interforniceal transventricular approaches were performed. The dissections were documented in a stepwise fashion using three-dimensional photographic image acquisition techniques and supplemented with representative cases to highlight pertinent surgical principles.

RESULTS

The anterior transcortical and interhemispheric corridors afford excellent access to the anterior two-thirds of the third ventricle with varying risks associated with frontal lobe versus corpus callosum disruption, respectively. The transcortical approach offers a more direct, oblique view of the ipsilateral lateral ventricle, whereas the transcallosal approach readily establishes biventricular access through a paramedian corridor. Once inside the lateral ventricle, intraventricular angled endoscopy further enhances access to the extreme poles of the third ventricle from either open transcranial approach. Subsequent selection of either the transforaminal, transchoroidal, or interforniceal routes can be performed through either craniotomy and is ultimately dependent on individual deep venous anatomy, the epicenter of ventricular pathology, and the concomitant presence of hydrocephalus or embryologic cava. Key steps described include positioning and skin incision; scalp dissection; craniotomy flap elevation; durotomy; transcortical versus interhemispheric dissection with callosotomy; the aforementioned transventricular routes; and their relevant intraventricular landmarks.

CONCLUSIONS

Approaches to the ventricular system for maximal safe resection of pediatric brain tumors are challenging to master yet represent foundational cranial surgical techniques. We present a comprehensive operatively oriented guide for neurosurgery residents that combines stepwise open and endoscopic cadaveric dissections with representative case studies to optimize familiarity with third ventricle approaches, mastery of relevant microsurgical anatomy, and preparation for operating room participation.

Surgical outcomes of open and laser interstitial thermal therapy approaches for corpus callosotomy in pediatric epilepsy

OBJECTIVE

Corpus callosotomy (CC) is a palliative surgical intervention for patients with medically refractory epilepsy that has evolved in recent years to include a less-invasive alternative with the use of laser interstitial thermal therapy (LITT). LITT works by heating a stereotactically placed laser fiber to ablative temperatures under real-time magnetic resonance imaging (MRI) thermometry. This study aims to (1) describe the surgical outcomes of CC in a large cohort of children with medically refractory epilepsy, (2) compare anterior and complete CC, and (3) review LITT as a surgical alternative to open craniotomy for CC.

METHODS

This retrospective cohort study included 103 patients <21 years of age with at least 1 year follow-up at a single institution between 2003 and 2021. Surgical outcomes and the comparative effectiveness of anterior vs complete and open versus LITT surgical approaches were assessed.

RESULTS

CC was the most common surgical disconnection (65%, n = 67) followed by anterior two-thirds (35%, n = 36), with a portion proceeding to posterior completion (28%, n = 10). The overall surgical complication rate was 6% (n = 6/103). Open craniotomy was the most common approach (87%, n = 90), with LITT used increasingly in recent years (13%, n = 13). Compared to open, LITT had shorter hospital stay (3 days [interquartile range (IQR) 2-5] vs 5 days [IQR 3-7]; p < .05). Modified Engel class I, II, III, and IV outcomes at last follow-up were 19.8% (n = 17/86), 19.8% (n = 17/86), 40.2% (n = 35/86), and 19.8% (n = 17/86). Of the 70 patients with preoperative drop seizures, 75% resolved postoperatively (n = 52/69).

SIGNIFICANCE

No significant differences in seizure outcome between patients who underwent only anterior CC and complete CC were observed. LITT is a less-invasive surgical alternative to open craniotomy for CC, associated with similar seizure outcomes, lower blood loss, shorter hospital stays, and lower complication rates, but with longer operative times, when compared with the open craniotomy approach.

Radiosurgical Corpus Callosotomy for Intractable Epilepsy: Retrospective Long-Term Safety and Efficacy Assessment in 19 Patients an Review of the Literature

BACKGROUND

Some patients suffering from intractable epileptic seizures, particularly drop attacks (DAs), are nonremediable by curative techniques. Palliative procedure carries a significant rate of surgical and neurological complications.

OBJECTIVE

To propose evaluation of safety and efficacy of Gamma Knife corpus callosotomy (GK-CC) as an alternative to microsurgical corpus callosotomy.

METHODS

This study included retrospective analysis of 19 patients who underwent GK-CC between 2005 and 2017.

RESULTS

Of the 19 patients, 13 (68%) had improvement in seizure control and 6 had no significant improvement. Of the 13/19 (68%) with improvement in seizures, 3 (16%) became completely seizure-free, 2 (11%) became free of DA and generalized tonic-clonic but with residual other seizures, 3 (16%) became free of DA only, and 5 (26%) had >50% reduction in frequency of all seizure types. In the 6 (31%) patients with no appreciable improvement, there were residual untreated commissural fibers and incomplete callosotomy rather than failure of Gamma Knife to disconnect. Seven patients showed a transient mild complication (37% of patients, 33% of the procedures). No permanent complication or neurological consequence was observed during the clinical and radiological workup with a mean of 89 (42-181) months, except 1 patient who had no improvement of epilepsy and then aggravation of the pre-existing cognitive and walking difficulties (Lennox-Gastaut). The median time of improvement after GK-CC was 3 (1-6) months.

CONCLUSION

Gamma Knife callosotomy is safe and accurate with comparable efficacy to open callosotomy in this cohort of patients with intractable epilepsy suffering from severe drop attacks.

Reversible splenial lesion after surgery for distant arteriovenous malformation: a case report

Isolated lesions of the corpus callosum are rare and may represent permanent but also transient responses to various pathology termed "reversible splenial lesion syndrome" (RESLES) when in light of relevant clinical presentation. We present the first case of the RESLES after elective surgery for distant arteriovenous malformation (AVM), followed by a slight speech disturbance and MRI verified small, oval, well-circumscribed area of apparent cytotoxic edema in the center of the corpus callosum splenium, which completely resolved within 15 days. Surgery for AVM is followed by the complex adaptation to a new vascular pattern, RESLES might develop, and should be suspected.

Balloon-Assisted Corpus Callosotomy. Reducing the Impact of Transcallosal Approaches

BACKGROUND

The interhemispheric transcallosal approach is widely used to remove intraventricular lesions. Corpus callosotomy gives immediate access to the ventricular chambers but is invasive in nature. Loss of callosal fibers, although normally tolerate, may cause disturbances ranging from a classical disconnection syndrome up to minor neuropsychological changes.

OBJECTIVE

To open an operative window in the corpus callosum through separation rather than disconnection of the white matter fibers.

METHODS

In 7 patients undergoing the interhemispheric transcallosal approach for intraventricular lesions, lying around or below the foramen of Monro, a stoma was created within the corpus callosum by using a 4F Fogarty catheter. The series included 3 colloid of the third ventricle, 2 thalamic cavernomas, 1 subependymoma, and 1 ependymoma of the foramen of Monro. We illustrate the technique and the clinico-radiological outcome, focusing on the size of callosotomy as seen on postoperative MRI.

RESULTS

The balloon-assisted corpus callosotomy provided a circular, smooth-walled access to the ventricular chambers, which allowed uncomplicated removal of the lesions. On postoperative MRI, the size of the callosotomy shrinked compared with surgery (2.8-6.4 mm at follow-up vs 6-9 mm as measured intraoperatively). No signs of disconnection syndrome or new permanent deficits were observed in this series.

CONCLUSION

The balloon-assisted technique produces a small callosotomy, without clinical consequences, showing a self-closing trend on postoperative MRI. This technique is a rewarding tool to reduce the impact of callosotomy while keeping the advantages of microsurgical interhemispheric approaches.

Corpus Callosotomy Is a Safe and Effective Procedure for Medically Resistant Epilepsy

Corpus callosotomy (CC) is an effective surgical treatment for medically resistant generalized or multifocal epilepsy (MRE). The premise of CC extrapolates from the observation that the corpus callosum is the predominant commissural pathway that allows spread and synchroneity of epileptogenic activity between the hemispheres. Candidacy for CC is typically reserved for patients seeking palliative epilepsy treatment with the goal of reducing the frequency of drop attacks, although reduction of other seizure semiologies (absence, complex partial seizures, and tonic-clonic) has been observed. A reduction in morbidity affiliated with evolution of surgical techniques to perform CC has improved the safety profile of the procedure without necessarily sacrificing efficacy.

Efficacy and safety of corpus callosotomy versus vagus nerve stimulation as long-term adjunctive therapies in children with Lennox–Gastaut syndrome

Objectives:

To compare the efficacy and safety of corpus callosotomy versus vagus nerve stimulation (VNS) as long-term adjunctive therapies in children with Lennox–Gastaut syndrome.

Methods:

This retrospective study was conducted in King Fahad Medical City between 2010 and 2019. The authors identified and followed 9 patients with Lennox–Gastaut syndrome (LGS) who underwent corpus callosotomy or VNS implantation for at least 12 months; seizure frequency and major complications were monitored. Five patients with a mean age of 10.8±1.3 years had corpus callosotomy, and 4 patients with a mean age of 13.8±3.9 years were implanted with VNS stimulators.

Results:

Reduction in seizure frequency was achieved in all 5 patients who underwent corpus callosotomy, with greater than 75% seizure reduction in more than 50% in one, and greater than 25% in 2 respectively. However, in those implanted with VNS, 2 (50%) patients achieved a reduction in seizure frequency of greater than 75% and 2 (50%) greater than 25%, respectively. No significant difference was observed between the 2 treatment groups. One patient who underwent corpus callosotomy suffered cerebrospinal fluid leakage, and swallowing difficulties in one patient who underwent VNS.

Conclusion:

Both corpus callosotomy and VNS are safe and effective as adjunctive treatments for LGS patients.

Transcallosal Suprachoroidal Approach for a Small Third Ventricular Colloid Cyst

BACKGROUND AND INTRODUCTION

The interhemispheric transcallosal approach provides an elegant pathway to access the lesions of the third ventricle. However, every step of this approach is fraught with hazards which must be negotiated delicately. A comprehensive knowledge of surgical anatomy coupled with technical skill is necessary for optimum surgical results.

OBJECTIVE

This video aims to address the surgical nuances of the suprachoroidal transcallosal approach while accessing the lesions around the foramen of Monro in the anterior and middle part of the third ventricle.

SURGICAL TECHNIQUE

A 16-year-old boy presented with worsening headaches with episodes of speech arrest and blank stare for 6 years, which had become more frequent over the past 4-5 months. Radiology showed a subcentimeteric colloid cyst at the foramen of monro. A transcallosal corridor was used to reach the foramen of monro, and the suprachoroidal access was adopted to uncover the colloid cyst and excise it completely preserving the deep veins.

RESULTS

The patient had uneventful recovery and radiology showed complete excision of the cyst.

CONCLUSION

Transcallosal approach, being minimally invasive, exploits the natural extra-axial corridor (interhemispheric) obviating the need for a cortical incision. The suprachoroidal approach mitigates the risks of thalamostriate vein injury, basal ganglia stroke, and hemiparesis.

Endoscopic Total Corpus Callosotomy and Pan Commissurotomy for Lennox-Gastaut Syndrome

BACKGROUND

Corpus callosotomy (CC) is a major disconnection procedure that functionally isolates the cerebral hemispheres, thereby interrupting the spread of epileptic activity from one hemisphere to the other. It is extremely useful in children suffering from non-localized drug refractory epilepsy, especially drop attacks. The technique has evolved from microscopic to minimally invasive endoscopic surgery. The extent of callosotomy also varies based on the institutional practices ranging from anterior 1/3^rd to total corpus callosotomies (TCC). The performance of TCC in conjunction with anterior, posterior, and hippocampal commissurotomies was described for the first time by the senior author from our institution.

OBJECTIVE

To describe the technique of performing endoscopic total corpus callosotomy, and pan commissurotomy using the interhemispheric corridor.

METHODS

A seven-year-old right-handed male child with seizure onset at the age of six months presented with three types of semiologies consisting of myoclonic jerks, frequent head drops and tonic posturing involving right upper and lower limbs with secondary generalization.

RESULTS

Video electroencephalography (VEEG) revealed diffuse slowing of the background, and slow spike and wave pattern. Generalized paroxysmal fast activity (GPFA) was noted in the VEEG, suggestive of LGS. MRI brain revealed bilateral parieto-occipital gliosis and gross brain atrophy. Ictal SPECT localized to left temporo-occipital area, while magnetoencephalography revealed bilateral temporal localization. Patient underwent TCC with pancommissurotomy. The patient was seizure-free (ILAE Class 3) at one-year follow up with no drop attacks, and significant reduction noted in other seizure types.

CONCLUSION

Endoscopic corpus callosotomy and pan commissurotomy using the interhemispheric corridor is an elegant and minimally invasive technique best suited for appropriately selected children with refractory epilepsy.

Surgery for IDH1/2 wild-type glioma invading the corpus callosum

BACKGROUND

Glioblastoma of the corpus callosum (ccGBM) are rare tumors, with a dismal prognosis marked by a rapid clinical deterioration. For a long time, surgical treatment was not considered beneficial for most patients with such tumors. Recent studies claimed an improved survival for patients undergoing extensive resection, albeit without integration of the molecular profile of the lesions. The purpose of this study was to investigate the effect of biopsy and surgical resection on oncological and functional outcomes in patients with IDH wild-type ccGBM.

METHODS

We performed a retrospective analysis of our institution's database of patients having been treated for high-grade glioma between 2005 and 2017. Inclusion criteria were defined as follows: patients older than 18 years, histopathological, and molecularly defined IDH wild-type glioma, major tumor mass (at least 2/3) invading the corpus callosum in the sagittal plane with a uni- or bilateral infiltration of the adjacent lobules. Surgical therapy (resection vs. biopsy), extent of resection according to the remaining tumor volume and adjuvant treatment as well as overall survival and functional outcome using the Karnofsky Performance Score (KPS) were analyzed.

RESULTS

Fifty-five patients were included in the study, from which the mean age was 64 years and men (n = 34, 61.8%) were more often affected than women (n = 21, 38.2%). Thirty (54.5%) patients were treated with stereotactic biopsy alone, while 25 patients received tumor resection resulting in 14.5% (n = 8) gross-total resections and 30.9% (n = 17) partial resections. The 2-year survival rate after resection was 30% compared to 7% after biopsy (p = 0.047). The major benefit was achieved in the group with gross-total resection, while partial resection failed to improve survival. Neurological outcome measured by KPS did not differ between both groups either pre- or postoperatively.

CONCLUSIONS

Our study suggests that in patients with corpus callosum glioblastoma, gross-total resection prolongs survival without negatively impacting neurological outcome as compared to biopsy.

Control of drop attacks with selective posterior callosotomy: Anatomical and prognostic data

OBJECTIVE

In a previous proof of concept study, selective posterior callosotomy achieved similar degree of control of drop attacks as total callosotomy, while sparing prefrontal interconnectivity. The present study aims to confirm this finding in a larger cohort and to provide anatomical and prognostic data.

METHODS

Fifty-one patients with refractory drop attacks had selective posterior callosotomy and prospective follow up for a mean of 6.4 years. Twenty-seven patients had post-operative magnetic resonance imaging (MRI) and 18 had tractography (DTI) of remaining callosal fibers. Pre and postoperative falls were quantified and correlated with demographic, clinical and imaging data.

RESULTS

Mean monthly frequency of drop attacks had a 95 % reduction, from 297 before to 16 after the procedure. Forty- one patients (80 %) had either complete or greater than 90 % control of the epileptic falls. Age and duration of epilepsy at surgery correlated with outcome (p values, respectively, 0.042 and 0.005). Mean index of callosal section along the posterior-to-anterior axis was 53.5 %. Extending the posterior section anterior to the midbody of the corpus callosum did not correlate with seizure control (p 0.91), providing fibers interconnecting the primary motor (M1) and caudal supplementary motor areas (SMA) were sectioned. Only one patient had a notable surgical complication which resolved in two days.

CONCLUSIONS

This level III cohort study with objective outcome assessment confirms that selective posterior callosotomy is safe and effective to control epileptic falls. Younger patients with smaller duration of epilepsy have better results. A posterior section contemplating the splenium, isthmus and posterior half of the body (posterior midbody) seems sufficient to achieve complete or almost complete control of drop attacks.

Atonic seizures in children: a meta-analysis comparing corpus callosotomy to vagus nerve stimulation

PURPOSE

Atonic seizures are associated with a particularly poor response to medical treatment. We performed a systematic review and meta-analysis to compare the efficacy of corpus callosotomy (CC) and vagus nerve stimulation (VNS) in the management of atonic seizures in the pediatric population.

METHODS

A literature search was performed in compliance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and recommendations, focusing on atonic seizures, CC, and VNS in pediatric populations. Pertinent clinical data were extracted and analyzed. Pooled effects between groups were calculated as standardized error (SE) with 95% confidence intervals (CIs). To assess for statistical significance, the Z-test was performed, using the pooled effect size (ES) and 95% CI for each intervention.

RESULTS

A total of 31 studies met the inclusion criteria, with 24 studies encompassing 425 children treated with CC and 7 studies encompassing 108 children treated with VNS. Twenty-four studies were included in a meta-analysis. There was a statistically significant difference in the primary outcome of atonic seizure control in favor of CC (overall effect size (ES) 0.73, 95% CI 0.69-0.77 for CC, ES 0.4, 95% CI 0.28-0.51 for VNS, p = 0.003). There was a higher rate of complications requiring reoperation in the CC cohort (6.6% vs. 3.8%) and a 14% rate of symptomatic disconnection syndrome.

CONCLUSIONS

While both techniques are safe, CC provides a much higher chance of effectively managing this morbid seizure type albeit with a higher risk of re-operation and disconnection syndrome.

Radiosurgical Corpus Callosotomy: A Review of Literature

BACKGROUND

Microsurgical callosotomy is a procedure still under debate and to best a palliative treatment for drug-resistant epilepsy. Unlike microsurgery, radiosurgical callosotomy is an underpracticed treatment option, with no definite account of its safety and outcome profile.

OBJECTIVE

To evaluate the safety, efficacy, and complication profile of radiosurgical callosotomy in the literature.

METHODS

PubMed, SCOPUS, Web of Science, and ResearchGate were reviewed for radiosurgery and callosotomy in the English language following PRISMA guidelines. The patient profile, radiosurgical parameters (dose and isodose), target volume, extent of radiosurgery (anterior third, half, or posterior third callosotomy), and seizure outcome were evaluated. We evaluated the role of radiosurgery as a primary or secondary treatment modality after microsurgery. A literature review was performed to identify the evidence of radiosurgery.

RESULTS

We identified 7 studies detailing 12 patients of mean age 22.8 years (range, 4-58 years) and a mean of 18.9 years of illness (range, 5-37 years). Five series performed Gamma Knife radiosurgery and 2 performed LINAC radiosurgery. The spectrum of seizures ranged from atonic seizures/drop attack (83%), generalized tonic-clonic seizures (75%), complex partial seizures (67%), absence seizures (50%), myoclonic seizures (33%), to focal seizures (16%). Four patients suffered from Lennox-Gastaut syndrome. The average seizure frequency in 11 patients was 297/month (range, 20/day to 15/month). Three patients became free of drop attacks and 2 free of generalized tonic-clonic seizures, and 1 became completely seizure free. The remaining patients continued to have seizures, albeit at a lower frequency. Complex partial seizures and myoclonic seizures were the least responsive seizure types to radiosurgical corpus callosotomy. All patients tolerated the procedure well. After radiosurgery, 3 patients developed symptomatic edema. The symptoms (headache, nausea, hemiparesis, and transient neurologic deficits) were controlled with a short course of steroids. Two patients needed redo radiosurgery (at the same target in 1 patient and complementary middle third callosotomy to previous anterior third callosotomy in another patient). There were no long-term complications.

CONCLUSIONS

Radiosurgery is a viable alternative to microsurgical callosotomy both as a primary and as a secondary treatment modality. It has a specific advantage of better neuropsychological outcomes with comparable seizure control. The neurosurgical community should adopt a more liberal approach with this indication.

Changes in cognitive function after resection of lesions in the anterior part of the lateral ventricle via an interhemispheric transcallosal approach

Anterior callosotomy to about 20 mm has been considered relatively safe empirically. The present study aimed to compare cognitive function before and after resection of tumors in the anterior part of the lateral ventricle. We analyzed 6 patients with intraventricular tumors located in the anterior horn or body of the lateral ventricle who underwent surgical excision via interhemispheric transcallosal approach at Osaka City University Hospital between March 2015 and August 2018. And clinical and imaging studies, neuropsychological function using MMSE, WAIS-III and WMS-R and surgical complications were retrospectively reviewed based on the medical records at our institution. As a result, 4 patients achieved gross total resection of the tumor and 2 patients achieved subtotal resection. 4 patients showed hydrocephalus, which disappeared in each case within 6 months after tumor resection. Mean length of callosotomy was 16.9 mm (range, 15.5-26.1 mm). One patient showed postoperative transient deficits including aphasia, microphonia, ballism in all extremities and hemiplegia, and another patient experienced subjective difficulty when talking. These symptoms disappeared within 3 months after tumor resection. Scores from the MMSE and WAIS-III showed no significant postoperative deterioration. Performance intelligence quotient (P = 0.04), full intelligence quotient (P = 0.04) and perceptual organization (P = 0.03) of WAIS-III were significantly improved after surgery compared with preoperatively. In conclusion, anterior corpus callosotomy of about 20 mm for intraventricular tumor in the anterior horn or body of the lateral ventricle might have little effect on cognitive function in the chronic phase, although the influence of hydrocephalus cannot be ignored.

Transcallosal, transchoroidal clipping of a hypothalamic collateral vessel aneurysm in Moyamoya disease

Peripheral collateral vessel aneurysms in Moyamoya disease (MMD) remain difficult to treat due to their deep location, small size, and vascular fragility. We report the case of an aneurysm localized in the hypothalamus, which was rapidly increasing in size with repeated hemorrhage despite revascularization surgery. Aneurysm clipping was performed to prevent further progress and rerupture with favorable outcome. To our best knowledge, this is the first description of a hypothalamic aneurysm in MMD being clipped via a transcallosal, transchoroidal approach through the third ventricle.

Computer-assisted planning for minimally invasive anterior two-thirds laser corpus callosotomy: A feasibility study with probabilistic tractography validation

•

Laser interstitial thermal therapy (LITT) is a novel minimally invasive technique for the treatment of epilepsy.

•

We test computer assisted planning with LITT to disrupt seizure spread.

•

Trajectory parameters and models were automatically generated from a single T1 image.

•

Probabilistic tractography revealed comparable interhemispheric disconnection to blinded expert surgeons.

Background

Anterior two-thirds corpus callosotomy is an effective palliative neurosurgical procedure for drug-refractory epilepsy that is most commonly used to treat drop-attacks. Laser interstitial thermal therapy is a novel stereotactic ablative technique that has been utilised as a minimally invasive alternative to resective and disconnective open neurosurgery. Case series have reported success in performing laser anterior two-thirds corpus callosotomy. Computer-assisted planning algorithms may help to automate and optimise multi-trajectory planning for this procedure.

Objective

To undertake a simulation-based feasibility study of computer-assisted corpus callostomy planning in comparison with expert manual plans in the same patients.

Methods

Ten patients were selected from a prospectively maintained database. Patients had previously undergone diffusion-weighted imaging and digital subtraction angiography as part of routine SEEG care. Computer-assisted planning was performed using the EpiNav™ platform and compared to manually planned trajectories from two independent blinded experts. Estimated ablation cavities were used in conjunction with probabilistic tractography to simulate the expected extent of interhemispheric disconnection.

Results

Computer-assisted planning resulted in significantly improved trajectory safety metrics (risk score and minimum distance to vasculature) compared to blinded external expert manual plans. Probabilistic tractography revealed residual interhemispheric connectivity in 1/10 cases following computer-assisted planning compared to 4/10 and 2/10 cases with manual planning.

Conclusion

Computer-assisted planning successfully generates multi-trajectory plans capable of LITT anterior two-thirds corpus callosotomy. Computer-assisted planning may provide a means of standardising trajectory planning and serves as a potential new tool for optimising trajectories. A prospective validation study is now required to determine if this translates into improved patient outcomes.

Frame-based stereotactic biopsy of deep-seated and midline structures in 511 procedures: feasibility, risk profile, and diagnostic yield

OBJECTIVES

We evaluated the feasibility, safety, and diagnostic yield of frame-based stereotactic biopsies (SB) in lesions located in deep-seated and midline structures of the brain to analyze these parameters in comparison to other brain areas.

PATIENTS AND METHODS

In a retrospective, tertiary care single-center analysis, we identified all patients who received SB for lesions localized in deep-seated and midline structures (corpus callosum, basal ganglia, pineal region, sella, thalamus, and brainstem) between January 1996 and June 2015. Study participants were between 1 and 82 years. We evaluated the feasibility, procedural complications (mortality, transient and permanent morbidity), and diagnostic yield. We further performed a risk analysis of factors influencing the latter parameters. Chi-square test, Student t test, and Mann-Whitney rank-sum test were used for statistical analysis.

RESULTS

Four hundred eighty-nine patients receiving 511 SB procedures (median age 48.5 years, range 1-82; median Karnofsky Performance Score 80%, range 50-100%, 43.8% female/56.2% male) were identified. Lesions were localized in the corpus callosum (29.5%), basal ganglia (17.0%), pineal region (11.5%), sella (7.8%), thalamus (4.3%), brainstem (28.8%), and others (1.1%). Procedure-related mortality was 0%, and permanent morbidity was 0.4%. Transient morbidity was 9.6%. Histological diagnosis was possible in 99.2% (low-grade gliomas 16.2%, high-grade gliomas 40.3%, other tumors in 27.8%, no neoplastic lesions 14.5%, no definitive histological diagnosis 0.8%). Only the pons location correlated significantly with transient morbidity (p < 0.001).

CONCLUSION

In experienced centers, frame-based stereotactic biopsy is a safe diagnostic tool with a high diagnostic yield also for deep-seated and midline lesions.

Cyclin-Dependent Kinase-Like 5 Deficiency Disorder: Clinical Review

Cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD) is a developmental encephalopathy caused by pathogenic variants in the gene CDKL5. This unique disorder includes early infantile onset refractory epilepsy, hypotonia, developmental intellectual and motor disabilities, and cortical visual impairment. We review the clinical presentations and genetic variations in CDD based on a systematic literature review and experience in the CDKL5 Centers of Excellence. We propose minimum diagnostic criteria. Pathogenic variants include deletions, truncations, splice variants, and missense variants. Pathogenic missense variants occur exclusively within the kinase domain or affect splice sites. The CDKL5 protein is widely expressed in the brain, predominantly in neurons, with roles in cell proliferation, neuronal migration, axonal outgrowth, dendritic morphogenesis, and synapse development. The molecular biology of CDD is revealing opportunities in precision therapy, with phase 2 and 3 clinical trials underway or planned to assess disease specific and disease modifying treatments.

Anaesthesia for a biopsy of corpus callosum in patient with a recent intra-operative anaphylaxis to an unknown anaesthetic allergen: a case report

BACKGROUND

Anaphylaxis in general anaesthesia occurs with a frequency of 1:5000-1:20000. This clinical summary reports on the use of an effective risk management strategy employing second line anaesthesia agents and alternative endotracheal intubation tools in a patient with a recent history of an intra-operative anaphylaxis to an unknown anaesthetic agent.

CASE PRESENTATION

A 71-year-old male presented for a repeat biopsy of corpus callosum 4 days following the cancellation of the procedure for a presumed anaphylactic reaction to an unknown anaesthetic agent. During the repeat care episode, the decision was made to proceed based on the urgent need for tissue diagnosis to facilitate further treatment and lack of feasibility for more definitive identification of the causative agent(s). A consideration was made of the optimum ways to manage and mitigate risk in this setting. The airway was managed using flexible endoscopic intubation in a spontaneously ventilating awake patient. Continuous remifentanil infusion was maintained throughout the case. Anaesthesia was maintained with sevoflurane at less than one MAC, with an uneventful completion of the biopsy of corpus callosum. All of the anaesthetic agents used during the prior care episode, with the exception of remifentanil, were avoided.

CONCLUSION

In cases of an anaphylaxis to an unknown anaesthetic allergen, anaesthetic strategy consists of careful risk mitigation and deployment of second agent approaches. Awake flexible endoscopic intubation and remifentanil infusion are viable alternatives to standard induction techniques.

Changes in functional brain network topology after successful and unsuccessful corpus callosotomy for Lennox-Gastaut Syndrome

Corpus callosotomy (CC) is an effective palliative surgical treatment for patients with Lennox-Gastaut Syndrome (LGS). However, research on the long-term functional effects of CC is sparse. We aimed to investigate these effects and their associated clinical conditions over the two years after CC. Long-term clinical EEG recordings of 30 patients with LGS who had good and bad seizure outcome after CC were collected and retrospectively studied. It was found that CC caused brain network 'hubs' to shift from paramedian to lateral regions in the good-recovery group, which reorganized the brain network into a more homogeneous state. We also found increased local clustering coefficients in patients with bad outcomes and decreases, implying enhanced network integration, in patients with good outcomes. The small worldness of brain networks in patients with good outcomes increased in the two years after CC, whereas it decreased in patients with bad outcomes. The covariation of small-worldness with the rate of reduction in seizure frequency suggests that this can be used as an indicator of CC outcome. Local and global network changes during the long-term state might be associated with the postoperative recovery process and could serve as indicators for CC outcome and long-term LGS recovery.

Corpus callosotomy

BACKGROUND

Corpus callosotomy is an effective, relatively low-risk, palliative procedure for a selected population of patients with medically intractable epilepsy. Here we describe this technique.

METHOD

An interhemispheric microsurgical approach is performed. Neuronavigation facilitates orientation. The callosal body is transected through to the roof of the ipsilateral ventricle using an ultrasonic aspirator; the genu and rostrum are then identified and also split. If a total callosotomy is performed, transection of the splenium is performed with care given to preserve the crus of the fornix.

CONCLUSIONS

Meticulous microsurgical technique and knowledge of the limbic system's anatomy is essential to keeping this procedure safe and effective.

Non-pharmacological interventions for people with epilepsy and intellectual disabilities

BACKGROUND

Approximately 30% of patients with epilepsy remain refractory to drug treatment and continue to experience seizures whilst taking one or more antiepileptic drugs (AEDs). Several non-pharmacological interventions that may be used in conjunction with or as an alternative to AEDs are available for refractory patients. In view of the fact that seizures in people with intellectual disabilities are often complex and refractory to pharmacological interventions, it is evident that good quality randomised controlled trials (RCTs) are needed to assess the efficacy of alternatives or adjuncts to pharmacological interventions.This is an updated version of the original Cochrane review (Beavis 2007) published in The Cochrane Library (2007, Issue 4).

OBJECTIVES

To assess data derived from randomised controlled trials of non-pharmacological interventions for people with epilepsy and intellectual disabilities.Non-pharmacological interventions include, but are not limited to, the following.• Surgical procedures.• Specialised diets, for example, the ketogenic diet, or vitamin and folic acid supplementation.• Psychological interventions for patients or for patients and carers/parents, for example, cognitive-behavioural therapy (CBT), electroencephalographic (EEG) biofeedback and educational intervention.• Yoga.• Acupuncture.• Relaxation therapy (e.g. music therapy).

SEARCH METHODS

For the latest update of this review, we searched the Cochrane Epilepsy Group Specialised Register (19 August 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) via CRSO (19 August 2014), MEDLINE (Ovid, 1946 to 19 August 2014) and PsycINFO (EBSCOhost, 1887 to 19 August 2014).

SELECTION CRITERIA

Randomised controlled trials of non-pharmacological interventions for people with epilepsy and intellectual disabilities.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the inclusion criteria and extracted study data.

MAIN RESULTS

One study is included in this review. When two surgical procedures were compared, results indicated that corpus callosotomy with anterior temporal lobectomy was more effective than anterior temporal lobectomy alone in improving quality of life and performance on IQ tests among people with epilepsy and intellectual disabilities. No evidence was found to support superior benefit in seizure control for either intervention. This is the only study of its kind and was rated as having an overall unclear risk of bias. The previous update (December 2010) identified one RCT in progress. The study authors have confirmed that they are aiming to publish by the end of 2015; therefore this study (Bjurulf 2008) has not been included in the current review.

AUTHORS' CONCLUSIONS

This review highlights the need for well-designed randomised controlled trials conducted to assess the effects of non-pharmacological interventions on seizure and behavioural outcomes in people with intellectual disabilities and epilepsy.

Distinct types of white matter changes are observed after anterior temporal lobectomy in epilepsy

Anterior temporal lobectomy (ATL) is commonly adopted to control medically intractable temporal lobe epilepsy (TLE). Depending on the side of resection, the degree to which Wallerian degeneration and adaptive plasticity occur after ATL has important implications for understanding cognitive and clinical outcome. We obtained diffusion tensor imaging from 24 TLE patients (12 left) before and after surgery, and 12 matched controls at comparable time intervals. Voxel-based analyses were performed on fractional anisotropy (FA) before and after surgery. Areas with postoperative FA increase were further investigated to distinguish between genuine plasticity and processes related to the degeneration of crossing fibers. Before surgery, both patient groups showed bilateral reduced FA in numerous tracts, but left TLE patients showed more extensive effects, including language tracts in the contralateral hemisphere (superior longitudinal fasciculus and uncinate). After surgery, FA decreased ipsilaterally in both ATL groups, affecting the fornix, uncinate, stria terminalis, and corpus callosum. FA increased ipsilaterally along the superior corona radiata in both left and right ATL groups, exceeding normal FA values. In these clusters, the mode of anisotropy increased as well, confirming fiber degeneration in an area with crossing fibers. In left ATL patients, pre-existing low FA values in right superior longitudinal and uncinate fasciculi normalized after surgery, while MO values did not change. Preoperative verbal fluency correlated with FA values in all areas that later increased FA in left TLE patients, but postoperative verbal fluency correlated only with FA of the right superior longitudinal fasciculus. Our results demonstrate that genuine reorganization occurs in non-dominant language tracts after dominant hemisphere resection, a process that may help implement the inter-hemispheric shift of language activation found in fMRI studies. The results indicate that left TLE patients, despite showing more initial white matter damage, have the potential for greater adaptive changes postoperatively than right TLE patients.

Palliative epilepsy surgery in Aicardi syndrome: a case series and review of literature

PURPOSE

Aicardi syndrome (AS) is a severe neurodevelopmental disorder characterized by the triad of seizures, agenesis of corpus callosum, and chorioretinal lacunae. Seizures in AS are typically frequent, of various types, and refractory to medical therapy. Optimal treatment of seizures in AS remains undetermined.

METHODS

We report a series of four patients with Aicardi syndrome who underwent surgical management of their epilepsy including two with corpus callosotomy (CC) of a partial corpus callosum and three with vagus nerve stimulator implantation.

RESULTS

Seizure outcome was variable and ranged from near complete resolution of seizures to worsening of seizure profile. The most favorable seizure outcome was seen in a patient with partial agenesis of the corpus callosum treated with CC.

CONCLUSIONS

Seizure outcome following CC or vagus nerve stimulation in patients with Aicardi syndrome is variable. Although palliative epilepsy surgery may result in improvement in the seizure profile in some patients, studies on larger patient cohorts are needed to identify the precise role that surgery may play in the multidisciplinary approach to controlling seizures in Aicardi syndrome.

A modern minimally invasive transcallosal approach to the third ventricle. A personal experience of 30 patients

INTRODUCTION

Expansive processes around the third ventricle have always been a major neurosurgical challenge. Despite all the technological and scientific progress recorded over the last few years, third ventricle tumors are still a very difficult pathology to approach due to their formidable complexity.Treating such a tumor demands a good knowledge of local anatomy, pathophysiology, pathology and a good capacity to integrate all the data gathered from the patient prior to and during surgery. Last but not least, the correct means to approach such a tumor involves using modern neuronavigation technology which might be too expensive to access in certain clinics (1,2).

OBJECTIVE

This article presents the personal experience of the authors, gathered while using a novel surgical approach,configured to maximize the success rate of interventions for tumors within the third ventricle, without using neuronavigation technology.

MATERIALS AND METHODS

The authors have developed a study of neuroanatomy using 30 adult human brains, without any pathological lesions, harvested during routine autopsies and analysed using a a standard protocol (Protocol of the Ludwig-Maximilians University Clinic of Neurosurgery, Laboratory of Microanatomy - Munich, Germany). The authors assessed a series of anatomic elements which were later used as landmarks to build the neurosurgical operative field. After completing the anatomic study the authors moved on to record morphometric data for 30 volunteers. The authors used sagittal T1 weighted images. The volunteers were males and females, all adults, with the mean age of 45.3 years. (The age interval: 21-83 years, sex distribution: 17 males and 13 females). The images were digitally enhanced and the specific targets were outlined using Corel Draw, thus allowing for a systematic identification of contours and landmarks. Each contour was recorded and saved as a sequence of dots. The next stage of the study, after having studied all the data recorded, consisted of establishing the appropriate transcallosal surgical corridor (transforaminal or inter forniceal) for each of the 30 patients (not to be mistaken with the 30 volunteers)who were admitted for third ventricle tumors and who were included in this study. After having performed surgery for there section of the above mentioned third ventricle tumors, the authors observed pre- and postoperative clinical data which were corroborated with the neuropsychological examination which was also performed prior to and after surgery.

CONCLUSIONS

The results obtained through observation and anatomical measurements have proven to be highly valuable in determining a standard access corridor through the corpuscallosum. The data gathered and the patient's MRI exam images helped obtain an optimal surgical corridor of the third ventricle. In what regards the surgical act in 23 cases (77%) the authors managed to achieve a complete resection of the tumor.In 6 cases (20%) the authors managed a subtotal resection of the tumors. In a single case the authors performed only a biopsy. A number of 24 patients (80%) achieved an excellent outcome (Glasgow Outcome Scale - GOS V). Minor deficits were recorded in 5 patients (17%) (disabled but independent)(GOS IV) No cases were recorded with serious impairment(GOS III) or vegetative state (GOS II). One patient with anaplastic glioma died 4 months after surgery after an initial favorable evolution. The tumor had spread to the hypothalamus. A single postoperative complication was linked to the surgical approach in a 73-year-old female patient who suffered a venous infarction due to a venous thrombosis in atributary vein of the superior sagittal sinus in the access area.The patient, after a slow recovery managed to improve her condition reaching GOS IV. There were no other complications connected to the surgical act.

Transcallosal approach to third ventricle tumors: how I do it

BACKGROUND

The transcallosal approach provides a direct corridor to the lesions lying in the third ventricle with distinct advantages over alternative routes, such as the possibility to use multiple corridors for tumor resection.

METHOD

Here we present a personal perspective of the surgery of tumors of the anterior portion of the third ventricle using this approach.

CONCLUSIONS

This approach requires the ability to move around many neurovascular, cortical, and white matter structures. Knowledge of regional anatomy and adherence to principles of microsurgery are basic requirements to obtain a favorable outcome.

Utilisation of intra-operative Doppler in the localisation of pericallosal artery during functional hemispherotomies for epilepsy: technical note

Functional hemispherotomy is an established technique for treating epilepsy secondary to hemispheric pathology. Corpus callosotomy and frontobasal disconnection are integral parts of this operation. To perform this, localisation of the pericallosal artery through the medial ventricular wall and subpial exposure of the A2 and A1 are required. Here, the authors present how intra-operative Doppler can be useful in helping to localise these arteries in the setting of abnormal neuroanatomy and significant brain shift.

Pediatric epilepsy surgery: anesthetic considerations

Despite advances in antiepileptic medication therapy, a significant number of pediatric patients with epilepsy have seizures that are not well controlled. This article provides anesthesiologists with an overview of seizures in the pediatric population, including evaluation, medical treatment, surgical options, and the anesthetic implications of caring for this special population.

["Palliative" surgical procedures in refractory epilepsy]

In some patients with refractory epilepsy, no resective surgery of the epileptogenic zone can be offered. This is the case when for instance the epileptogenic zone is located in an eloquent region (motor, language or visual) or when there are several epileptogenic zones. When disabling seizures persist despite the medical treatment, several surgical procedures can be proposed with the aim of decreasing the seizure frequency. Among these procedures, we review briefly here vagus nerve stimulation, the various brain stimulations procedures, multiples subpial transsections, and the corpus callosotomy. For each procedure, we will discuss its indication and outcome.

[Anesthetic management of a child with Lennox-Gastaut syndrome]

General anesthesia was given twice to a 9-year-old girl with Lennox-Gastaut syndrome (LGS). LGS is one of the catastrophic forms of childhood epilepsy, and very few reports describe its anesthetic management. The anesthetic concern in LGS patients is a possibility of perioperative epilepsy due to proconvulsive effects of anesthesia-related drugs and due to the interaction between anesthetics and therapeutic drugs. Fortunately, her perioperative course was uneventful. The patients having LGS should be placed under careful observation postoperatively.

Ectopic recurrence of craniopharyngioma along the surgical route: case report and literature review

We present a 22-year-old woman with an ectopic recurrence of a craniopharyngioma. The patient presented first with a visual field deficit, and a craniopharyngioma was removed via an interhemispheric transcallosal approach. Magnetic resonance imaging (MRI) performed at 1 month, and then at 1 year after surgery showed complete removal of the lesion. However, at 4 years, MRI showed the presence of a small tumor in the right medial frontal lobe attached to the falx and along the previous surgical route. We present possible explanations for the ectopic recurrence and literature review.

[Transcallosal-interforniceal approach treatment of hypothalamic astrocytoma in children]

OBJECTIVE

To explore the clinical features, diagnosis and efficiency of transcallosal-interforniceal approach treatment of hypothalamic astrocytoma in children.

METHODS

A total of 42 pediatric cases of hypothalamic astrocytoma were operated by transcallosal-interforniceal approach. All cases received post-operative radiotherapy and follow-up visits. The clinical and imaging data were analyzed retrospectively.

RESULTS

High ICP and hypothalamic lesions were the main clinical manifestations. All patients suffering from hydrocephalus were operated by transcallosal-interforniceal approach. Seventeen cases received subtotal resection and 25 in great part. None died from operation. All cases received post-operative radiotherapy. Twenty-nine cases were followed up for 1 to 7 years. Among which, 25 led a normal life and 4 stayed in a fair condition.

CONCLUSIONS

Hypothalamic astrocytoma in children have some characteristic in clinical manifestations and neuroradiological examinations. Transcallosal-interforniceal approach is an effective method of treating hypothalamic astrocytoma in children. Total removal is not imperative. And radiotherapy should be performed.

[Guidelines for the surgical treatment of the movement disorders and epilepsy. Grupo de Cirugía Funcional de la Sociedad Española de Neurocirugía (SENEC)]

The guidelines for the surgical treatment of the movement disorders and epilepsy have been performed by the functional and stereotactic group of the Spanish Society of Neurosugery (SENEC). The guidelines are recomendations in terms of indication for surgery including timing and methods. The format are supported by prospective studies based in scientific evidence and the expert opinion of the group.

[Complications after transcallosal transseptal interforniceal resection of hypothalamic hamartoma: analysis of 37 cases]

OBJECTIVE

To summarize the post-operative complications of resection of hypothalamic hamartoma (HH) through transcallosal transseptal interforniceal approach.

METHODS

Thirty-seven HH patients, 26 males and 11 females, aged 8.7 underwent resection of the tumor via the transcallosal transseptal interforniceal approach. The symptoms and blood electrolytes were observed.

RESULTS

After operation blood electrolyte test showed that 8 cases were normal, 19 cases showed hyponatremia as prime abnormality, and 10 cases had hypernatremia primarily. Among the 19 cases with hyponatremia transient apathy occurred in 2 cases, general epilepsy occurred in one patient, continuous minor epilepsy occurred in another one, 4 patients suffered minor epilepsy, 25 had fever the temperature of 3 of which were beyond 40 degrees C, and 2 had transient diabetes insipidus and 1 had diabetes.

CONCLUSION

Resection of HH through the transcallosal transseptal interforniceal approach achieves significant improvement of gelastic seizures with fewer complications. The most common complication is disturbance of serum natrium, which, however, is mild and well managed.

Transcallosal transbiforaminal approach to the third ventricle

BACKGROUND

Colloid cysts are benign intracranial lesions but can show signs of severe obstructive hydrocephalus and present with sudden death. The approaches to colloid cysts have been described by many authors. The treatment modalities can be classified as endoscopic and microsurgical. Bilateral access through the foramen is commonly used with transcallosal surgery to reach the third ventricle but has never been described. Cystic lesions can be excised safely with both approaches but the excision of a solid lesion is still challenging despite advances in microsurgical techniques.

METHODS

After routine callosotomy, each foramen of Monroe can be identified with the landmarks of the lateral ventricle. The foramens can be widened with limited manipulation. The solid lesion can be excised with limited traction of the third ventricle and surrounding neural structures. Tumor control can be achieved with the biforaminal approach but the tumor excision should be performed from the right foramen due left side forniceal memory dominance.

RESULTS

The postoperative period was uneventful, and the patient was discharged without any memory deficit.

CONCLUSION

Manipulation of both fornices increases the risk of significant memory system deficits. Safer and harmless excision can be achieved with the transbiforaminal approach if the tumor excision is performed from the right foramen.

Corollary discharge and spatial updating: when the brain is split, is space still unified?

How does the brain keep track of salient locations in the visual world when the eyes move? In parietal, frontal and extrastriate cortex, and in the superior colliculus, neurons update or 'remap' stimulus representations in conjunction with eye movements. This updating reflects a transfer of visual information, from neurons that encode a salient location before the saccade, to neurons that encode the location after the saccade. Copies of the oculomotor command - corollary discharge signals - must initiate this transfer. We investigated the circuitry that supports spacial updating in the primate brain. Our central hypothesis was that the forebrain commissures provide the primary route for remapping spatial locations across visual hemifields, from one cortical hemisphere to the other. Further, we hypothesized that these commissures provide the primary route for communicating corollary discharge signals from one hemisphere to the other. We tested these hypotheses using the double-step task and subsequent physiological recording in two split-brain monkeys. In the double-step task, monkeys made sequential saccades to two briefly presented targets, T1 and T2. In the visual version of the task, the representation of T2 was updated either within the same hemifield ("visual-within"), or across hemifields ("visual-across"). In the motor version, updating of the visual stimulus was always within-hemifield. The corollary discharge signal that initiated the updating, however, was generated either within the same hemisphere ("motor-within") or in the opposite hemisphere ("motor-across"). We expected that, in the absence of the forebrain commissures, both visual-across and motor-across conditions would be impaired relative to their "within" controls. In behavioral experiments, we observed striking initial impairments in the monkeys' ability to update stimuli across visual hemifields. Surprisingly, however, both animals were ultimately capable of performing the visual-across sequences of the double-step task. In subsequent physiological experiments, we found that neurons in lateral intraparietal cortex (LIP) can remap stimuli across visual hemifields, albeit with a reduction in the strength of remapping activity. These behavioral and neural findings indicate that the transfer of visual information is compromised, but by no means abolished, in the absence of the forebrain commissures. We found minimal evidence of impairment of the motor-across condition. Both monkeys readily performed the motor-across sequences of the double-step task, and LIP neurons were robustly active when within-hemifield updating was initiated by a saccade into the opposite hemifield. These results indicate that corollary discharge signals are available bilaterally. Altogether, our findings show that both visual and corollary discharge signals from opposite hemispheres can converge to update spatial representations in the absence of the forebrain commissures. These investigations provide new evidence that a unified and stable representation of visual space is supported by a redundant circuit, comprised of cortical as well as subcortical pathways, with a remarkable capacity for reorganization.

Tumors of the lateral ventricle: the factors that affected the preference of the surgical approach in 46 patiens

AIM

Optimal surgical pathway for lateral ventricle tumors is still controversial. The purpose of this study is to discuss the factors that affected the preference of the surgical techniques for removing lateral ventricle tumors.

MATERIAL AND METHODS

46 consecutive patients underwent operation for lateral ventricle tumors. The mean age was 36 years. Preoperative magnetic resonance imaging (MRI) images were examined to determine the location, expansion and size of each tumor. The transcallosal approach was used in 25 patients, and the transcortical approach was used in 21 patients. We performed MRI to determine the tumor size and recurrence or increased size of the residual tumor.

RESULTS

Total resection was performed in 31 patients. Only one patient, with glioblastoma, died due to hepatic encephalopathy and intraventricular hemorrhage after the operation. Additional neurological deficits were seen 4 patients, and postoperative seizure occurred in one patient. The mean duration of follow-up was 38,37 months.

CONCLUSION

Lateral ventricle tumors can be treated best by careful selection of the surgical approach according to localization of the tumor within the ventricle, the expansion side of the tumor, the size of the tumor, the origin of the vascular feeding branches, the venous drainage, and the relationship of the structures, and the histopathological features.

[Epilepsy surgery during infancy and early childhood in France]

BACKGROUND AND PURPOSE

We present the epilepsy surgery activity in infants and children at the Fondation Rothschild Hospital, the main center dedicated to this activity in France.

METHOD

A prospective study was conducted from 2003 to 2007 based on three populations: (1) children selected as candidates for surgery, (2) children undergoing presurgical evaluation and (3) children undergoing surgical procedures for epilepsy.

RESULTS

Children selected as candidates for surgery: 304 children were referred and discussed by our multidisciplinary staff. They came from Paris and its suburbs (40%), the provinces (43%) or from other countries (14%). Sixty-one percent of them were included in our surgery program and 24% were excluded. Sixty-one percent of them were under 10 years of age. Children undergoing presurgical evaluation: 296 children were recorded: 140 EEG (47%), 46 with foramen ovale electrodes (16%) and 110 with invasive recording techniques (37%). Seventy percent of these children were under 10 years of age. Children undergoing surgical procedures: 316 children underwent surgery; 68% of them were under 10 years of age. The surgical procedures were focal resection (136 children), vertical parasagittal hemispherotomy (77 children), resection and or disconnection for hypothalamic hamartoma (69 children) and 34 had palliative surgery (callosotomy or vagal nerve stimulation).

CONCLUSION

Eighty to 100 children undergo surgery each year in our department for drug-resistant partial epilepsy; 70% of them are less than 10 years of age. This activity is part of a network of pediatric neurologists who are deeply involved in treatment of severe epilepsy in children.