A Potential Risk of Radiation-Induced Cavernous Malformations Following Adjuvant Gamma Knife Radiosurgery for Mesial Temporal Lobe Epilepsy

Objective

Several clinical studies have explored the feasibility and efficacy of radiosurgical treatment for mesial temporal lobe epilepsy, but the long-term safety of this treatment has not been fully characterized. This study aims to report and describe radiation-induced cavernous malformation as a delayed complication of radiosurgery in epilepsy patients.

Methods

The series includes 20 patients with mesial temporal lobe epilepsy who underwent Gamma Knife radiosurgery (GKRS). The majority received a prescribed isodose of 24 Gy as an adjuvant treatment after anterior temporal lobectomy.

Results

In this series, we identified radiation-induced cavernous malformation in three patients, resulting in a cumulative incidence of 18.4% (95% CI, 6.3 to 47.0%) at an eight-year follow-up. These late sequelae of vascular malformation occurred between 6.9 and 7.6 years after GKRS, manifesting later than other delayed radiation-induced changes, such as radiation necrosis. Neurological symptoms attributed to intracranial hypertension were present in those three cases involving cavernous malformation. Of these, two cases, which initially exhibited an insufficient response to radiosurgery, ultimately demonstrated seizure remission following the successful microsurgical resection of the cavernous malformation.

Conclusion

All things considered, the development of radiation-induced cavernous malformation is not uncommon in this population and should be acknowledged as a potential long-term complication. Microsurgical resection of cavernous malformation can be preferentially considered in cases where the initial seizure outcome after GKRS is unsatisfactory.

Drug-resistant temporal lobe epilepsy with temporal encephaloceles: How far to resect

PURPOSE

This study sought to evaluate the impact of surgical extent on seizure outcome in drug-resistant temporal lobe epilepsy (DR-TLE) with temporal encephaloceles (TE).

METHODS

This was a single-institution retrospective study of patients who underwent surgery for DR-TLE with TE between January 2008 and December 2020. The impact of surgical extent on seizure outcome was evaluated. In a subset with dominant DR-TLE, the impact of surgical extent on neuropsychometric outcome was evaluated.

RESULTS

Thirty-four patients were identified (female, 56%; median age at surgery, 43 years). TE were frequently overlooked on initial magnetic resonance imaging (MRI), with encephaloceles only detected after repeat or expert re-review of MRI, additional multi-modal imaging, or intra-operatively in 31 (91%). Sixteen (47%) underwent limited resections, including encephalocele resection only (n = 5) and encephalocele resection with more extensive temporal corticectomy sparing the amygdala and hippocampus (n = 11). The remainder (n = 18, 53%) underwent standard anterior temporal lobectomy and amygdalohippocampectomy (ATLAH). Limited resection was performed more frequently on the left (12/17 vs. 4/17, p = 0.015). Twenty-seven patients (79%) had a favourable outcome (Engel I/II), and 17 (50%) were seizure-free at the last follow-up (median seizure-free survival of 27.3 months). There was no statistically significant difference in seizure-free outcomes between limited resection and ATLAH. In dominant DR-TLE, verbal memory decline was more likely after ATLAH than limited resection (3/4 vs. 0/9, p = 0.014).

CONCLUSION

Expert re-review of imaging and multi-modal advanced imaging improved TE identification. There was no statistical difference in seizure-free outcomes based on surgical extent. Preservation of verbal memory supports limited resection in dominant temporal cases.

Recovery of glymphatic system function in patients with temporal lobe epilepsy after surgery

OBJECTIVES

To investigate the recovery of human glymphatic system (GS) function in patients with temporal lobe epilepsy (TLE) after successful anterior temporal lobectomy (ATL) using diffusion tensor image analysis along the perivascular space (DTI-ALPS).

METHODS

We retrospectively analysed DTI-ALPS index in 13 patients with unilateral TLE before and after ATL, and compared the index with 20 healthy controls (HCs). Two-sample t tests and paired t tests were performed to analyse differences in the DTI-ALPS index between patients and HCs. The Pearson correlation analysis was used to observe the relationship between the disease duration and GS function.

RESULTS

The DTI-ALPS index before ATL was significantly lower in the hemisphere ipsilateral to the epileptogenic foci than in the contralateral hemisphere of the patients (p < 0.001, t =  - 4.81) and in the ipsilateral hemisphere of the HCs (p = 0.007, t =  - 2.90). A significant increase in the DTI-ALPS index was found in the hemisphere ipsilateral to the epileptogenic foci after successful ATL (p = 0.01, t =  - 3.01). In addition, the DTI-ALPS index of the lesion side before ATL was significantly correlated with disease duration (p = 0.04, r =  - 0.59).

CONCLUSIONS

DTI-ALPS may be used as a quantitative biomarker evaluating surgical outcomes and TLE disease duration. DTI-ALPS index may also help localise epileptogenic foci in unilateral TLE. Overall, our study suggests that GS may potentially serve as a new method for the management of TLE and a new direction for investigating the mechanism of epilepsy.

KEY POINTS

• DTI-ALPS index may contribute to epileptogenic foci lateralisation in TLE. • DTI-ALPS index is a potential quantitative feature evaluating surgical outcomes and TLE disease duration. • The GS provides a new perspective for the study of TLE.

Epilepsy surgery for dominant-side mesial temporal lobe epilepsy without hippocampal sclerosis

Although anterior temporal lobectomy (ATL) is an established surgery for medically intractable mesial temporal lobe epilepsy (MTLE), it can harm memory function, especially in dominant-side MTLE patients without hippocampal sclerosis (HS). To avoid this complication, multiple hippocampal transection (MHT) was developed, but its efficacy has not been fully elucidated. We report the detailed treatment results of MHT compared with that of ATL. We retrospectively analysed the records of 30 patients who underwent surgery for dominant-side MTLE. ATL was completed for 23 patients with HS, and MHT was completed for 7 patients without HS. The seizure control status, number of anti-seizure medicines, neurocognitive function, and psychiatric disorders of each patient were reviewed. The mean follow-up period was 70 months. Seizure control of Engel class I was achieved in 16 patients (70%) in the ALT group versus 5 patients (71%) in the MHT group. The mean number of anti-seizure medicines administered in the ATL group changed significantly from 2.4 to 1.9 (p = 0.01), while that in the MHT group was unchanged (from 2.1 to 2.0, p = 0.77). Eleven patients (48%) in the ATL group developed psychiatric disorders during the postoperative follow-up period, whereas no psychological complications were observed in the MHT group. Neither group showed neurocognitive decline after the surgery in any of the WAIS-III or WMS-R subtests. In conclusion, MHT may achieve reasonable postoperative seizure reduction, preserve neurocognitive function, and reduce postoperative psychiatric complications. Therefore, it can be considered as a therapeutic option for dominant-side MTLE without HS.

Avoidance of Pitfalls and Complications During Surgery for Temporal Lobe Epilepsy

Anterior temporal lobectomy with amygdalohippocampectomy is the most common epilepsy surgery, which, in cases of mesial temporal lobe epilepsy caused by mesial temporal sclerosis, usually leads to improvements in seizure control, cognitive function, and quality of life. Nevertheless, while the primary goal of intervention is achieved in a large majority of patients, a small number of them, unfortunately, encounter complications. Some morbidity is nonspecific and may be noted after any craniotomy (e.g., surgical site infections, meningitis, bone flap osteomyelitis, and operative site or craniotomy-related hematomas). On the other hand, certain complications are specifically associated with surgery for temporal lobe epilepsy and can be discussed from the etiological standpoint: mechanical injuries of the brain; injury of eloquent neuronal structures; arterial and venous injuries; cerebral venous thrombosis; remote cerebellar hemorrhage; and postoperative hydrocephalus, seizures, and psychiatric disorders. In many cases, these complications are manifested in the early postoperative period by alterations of consciousness and a focal neurological deficit, and it may require immediate decisions on their appropriate management.

Temporal Encephalocele: A Treatable Etiology of Drug-Resistant Pediatric Temporal Lobe Epilepsy

BACKGROUND

Temporal lobe encephaloceles (TEs) are a rare cause of drug-resistant temporal lobe epilepsy (DR-TLE), with head trauma and obesity identified as risk factors in adults. This study evaluated the clinical characteristics of childhood-onset DR-TLE due to TE.

METHODS

This is a single-institution retrospective review of childhood-onset DR-TLE with radiographic TE identified between 2008 and 2020. The epilepsy history, brain imaging features, and surgical outcomes were collected.

RESULTS

Eleven children with DR-TLE due to TE were included (median age at epilepsy onset was 11 years, interquartile range 8.5 to 13.5 years). Median latency between epilepsy diagnosis and TE detection was 3 years (range of 0 to 13 years). None had history of head trauma. Body mass index greater than 85 percentile for age and sex was seen in 36% of the children. No patient had bilateral TE identified. TEs were diagnosed based on epilepsy surgery conference re-review of imaging in 36% of cases. All herniations were contained defects without osseous dehiscence. Regional fluorodeoxyglucose (FDG) hypometabolism ipsilateral to the encephalocele was seen in all children who had FDG-positron emission tomography (PET) of the brain. Of the children who had surgery, 70% were seizure free or had nondisabling seizures at last follow-up (mean follow-up 52 months).

CONCLUSIONS

TE is a surgically remediable etiology of DR-TLE in childhood. TEs are often overlooked at pediatric epilepsy diagnosis, calling for the need to increase awareness of this entity. FDG-PET temporal hypometabolism in children with presumed nonlesional DR-TLE should be carefully examined for occult TEs.

Sleep macrostructure and cyclic alternating pattern in patients who underwent surgery for hippocampal sclerosis: A prospective controlled polysomnographic study

INTRODUCTION

Temporal lobe epilepsy due to hippocampal sclerosis (TLE-HS) is one of the most common drug-resistant epilepsy. Surgery is currently accepted as an effective and safe therapeutic approach compared to antiseizure medications (ASMs). The study aims to evaluate the effect of surgical treatment of TLE-HS on sleep profile and architecture by subjective and objective evaluation of sleep in basal condition after one month and one year.

METHODS

Thirteen patients with TLE-HS were recruited to undergo overnight polysomnography and a subjective evaluation of nocturnal sleep utilizing the Pittsburgh Sleep Quality Index (PSQI) and daytime somnolence through the Epworth Sleepiness Scale (ESS) in basal condition (T0), one month (T1) and one year after surgery (T2), respectively. Thirteen healthy controls (HC) matched for age, sex and BMI were recruited. Scoring and analysis of sleep macrostructure and cyclic alternating pattern (CAP) parameters were performed.

RESULTS

The comparison between patients in basal condition (T0) and HC showed a significant lower sleep efficiency (p = 0.003) and REM percentage (p < 0.001). Regarding CAP, patients at T0 showed higher total CAP rate (p < 0.001), CAP rate in N2 (p < 0.001), higher A3 (%) (p = 0.001), higher mean duration of A1 (p = 0.002), A3 index (p < 0.001), cycle in sequences (p < 0.001), lower B duration (p < 0.001), cycle mean duration (p < 0.001) than HC. Surgery did not induce significant changes in nocturnal macrostructural polysomnographic variables in T1 and T2. Lower CAP rate (T1 vs T0 and T2 vs T0 p < 0.001), CAP rate in N3 (T1 vs T0 and T2 vs T0 p < 0.001), A3 (%) (T1 vs T0 and T2 vs T0 p < 0.001); lower phase A2 index (T1 vs T0 p < 0.001) and A3 index (T1 vs T0 p < 0.001), lower phase A1 index (T2 vs T0 p < 0.001) and cycle in sequences (T2 vs T0 p = 0.002) higher B mean duration (T2 vs T0 p = 0.002). No significant differences were found between T1 and T2 in CAP parameters.

CONCLUSION

We found a significant NREM sleep instability in patients with TLE-HS compared with HC. In addition, anterior temporal lobectomy (ATL) induced a significant improvement in sleep continuity as evaluated by cyclic alternating pattern already one month later and this effect persisted after one year. ALT seems to restore a more resilient sleeping brain.

Altered Resting State Networks Before and After Temporal Lobe Epilepsy Surgery

OBJECTIVES

To explore the resting state networks (RSNs) alterations in patients with unilateral mesial temporal lobe epilepsy (mTLE) before and after successful surgery.

METHODS

Resting-state functional MRI and T1-weighted structural MRI were obtained in 37 mTLE patients who achieved seizure freedom after anterior temporal lobectomy. Patients were scanned before surgery and at two years after surgery. Twenty-eight age- and sex-matched healthy controls were scanned once. Functional connectivity (FC) changes within and between ten common RSNs before and after surgery, and FC changes between hippocampus and RSNs were explored.

RESULTS

Before surgery, decreased FC was found within visual network and basal ganglia network, while after surgery, FC within basal ganglia network further decreased but FC within sensorimotor network and dorsal attention network increased. Before surgery, between-network FC related to basal ganglia network, visual network and dorsal attention network decreased, while between-network FC related to default mode network increased. After surgery, between-network FC related to visual network and dorsal attention network significantly increased. In addition, before surgery, ipsilateral hippocampus showed decreased FC with visual network, basal ganglia network, sensorimotor network, default mode network and frontoparietal network, while contralateral rostral hippocampus showed increased FC with salience network. After surgery, no obvious FC changes were found between contralateral hippocampus and these RSNs.

CONCLUSION

MTLE patients showed significant RSNs alterations before and after surgery. Basal ganglia network showed progressive decline in functional connectivity. Successful surgery may lead to RSNs reorganization. These results provide preliminary evidence for postoperative functional remodeling at whole-brain-network level.

Anterior temporal lobectomy: A cross-sectional observational study of potential surgical candidates at a single institute

BACKGROUND

Epilepsy is a common neurological disorder, associated with serious cognitive, physical, and psychosocial burdens. Mesial temporal lobe epilepsy (mTLE) is the commonest form of focal epilepsy. The aim of this study was to establish the incidence of patients with electroencephalographic epileptiform discharges consistent with mTLE attending a tertiary hospital in South Africa, and determine whether these patients may be candidates for anterior temporal lobectomy.

METHODS

This was a cross-sectional observational study of all patients receiving scalp electroencephalograms (EEG) performed at the Groote Schuur Hospital Neurophysiology laboratory during the period January 1, 2017-December 31, 2019. Where magnetic resonance imaging (MRI) brain scans had been performed, these were assessed for corroborative evidence of mTLE.

RESULTS

Over the 3-year period, 4 342 EEGs were assessed. A total of 411 (11%) showed epileptiform discharges consistent with all epilepsy types. Of these, 327 (69%) were of focal onset and 108 (33% of all focal onset epilepsies) were consistent with mTLE. Of the patients with electroencephalographic features of mTLE, only 27 (25%) had had MRI brain scans performed according to an epilepsy surgery protocol. None of these patients had been considered for surgery.

CONCLUSION

Surgery, especially anterior temporal lobectomy, is widely acknowledged to be an efficacious and cost-effective intervention in patients with drug-resistant mTLE. The findings of our study suggest that patients with mTLE in our setting are under-investigated for potential surgery; and that it is under-utilized. These findings are in line with similar studies in both well-resourced and resource-constrained countries. Our study also highlights the utility of EEG as a practical screening tool to identify potential surgical candidates, as well as the establishment of an EEG and MRI database to assist in recognizing these patients.

Cognitive and functional outcomes following a traumatic brain injury sustained 22 years after epilepsy surgery: A case report

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Long-term outcomes were presented for a patient status post epilepsy surgery and TBI.

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Cognitive stability was documented over a 22-year follow-up period.

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Good cognitive and functional outcomes were demonstrated in late life.

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Protective factors include seizure outcome, cognitive reserve, and medical status.

Anterior temporal lobectomy (ATL) is an effective treatment for drug-resistant epilepsy, and risk for post-surgical naming and verbal memory decline after dominant hemisphere ATL is well-established. However, less is known about later life cognitive and functional outcomes following ATL performed in early or mid-life, as there are few studies that report very long-term outcomes, and the intersection of epilepsy and the aging process is not well-understood. Factors that may promote healthy cognitive aging or confer increased risk for cognitive decline in late life for those with seizure onset in early or mid-life have yet to be determined. This case report describes an individual with drug-resistant epilepsy who was treated with left ATL in mid-life, and then subsequently sustained a moderate traumatic brain injury 22 years later. The excellent recovery and remarkable stability of cognitive performance over time may be associated with several protective factors such as favorable seizure outcome, high cognitive reserve, and the absence of co-occurring medical conditions. This case also highlights the clinical utility of serial neuropsychological testing at multiple timepoints across the lifespan for those with epilepsy, and the importance of considering the clinical significance, or functional impact, of cognitive deficits in this population.

Costs Associated with Laser Interstitial Thermal Therapy Are Lower Than Anterior Temporal Lobectomy for Treatment of Temporal Lobe Epilepsy

BACKGROUND

Laser interstitial thermal therapy (LITT) is a minimally invasive alternative to anterior temporal lobectomy (ATL) for treatment of temporal lobe epilepsy. It has gained popularity as familiarity with technique increases and outcomes are better characterized. There has been no direct cost comparison between the 2 techniques in literature to date. The current study directly compares hospital costs associated with LITT with those of ATL patients and analyzes the factors potentially responsible for those costs.

METHODS

Patients who underwent ATL (27) and LITT (15) were retrospectively reviewed for total hospital costs along with demographic, surgical, and postoperative factors potentially affecting cost. T-tests were used to compare costs and independent linear regressions, and hierarchical regressions were used to examine predictors of cost for each procedure.

RESULTS

Mean hospital costs of admission for single-trajectory LITT ($104,929.88) were significantly less than for ATL ($134,980.04) (P = 0.001). In addition, length of stay, anesthesia costs, operative room costs, and postoperative hospitalization costs were all significantly lower in LITT.

CONCLUSIONS

Given the minimally invasive nature of LITT, it is associated with shorter length of stay and lower hospital costs than ATL in the first head-to-head comparison of procedural costs in literature to date. Long-term efficacy as it relates to these costs associated with LITT and ATL should be further investigated to better characterize the utility of LITT in temporal lobe epilepsy patients.

Recovery of cortical atrophy in patients with temporal lobe epilepsy after successful anterior temporal lobectomy

The aims of this study were to investigate whether the cortical atrophy caused by temporal lobe epilepsy (TLE) was reversible after successful anterior temporal lobectomy (ATL) and to further observe whether possible changes are related to age at surgery and cognitive changes. Twelve patients with unilateral mesial TLE who received ATL and remained seizure free in one year follow-up were included. They underwent two MRI scans few days before and oneyear after surgery. Thirty age- and sex-matched healthy participants were recruited as controls. Group comparisons were used to test the differences in cortical thickness (CTh) between the pre-/postsurgical patients and controls. Longitudinal test was used to directly show postsurgical changes of the patients. Besides, the correlations between regional cortical volume (CVo) changes and age at surgery or cognitive changes were also tested. Compared with controls, the patients with TLE showed dispersed cortical thinning especially in the bilateral frontal lobes before surgery and no significant cortical thinning except for cortices near the resected areas after surgery. The longitudinal analysis showed CTh increment in the ipsilateral precentral and postcentral gyrus, cuneus and widespread in the contralateral cortex. In the volumetric analysis, the CVo changes in the contralateral hemisphere were negatively correlated with age at surgery and positively correlated with MoCA score changes. This study suggests that the cortical atrophy caused by TLE could recover after successful ATL. The recovery ability is greater in younger subjects and is positively related to cognitive recovery. These findings could serve as new clues that patients with TLE can benefit from timely and successful ATL.

Psychiatric alterations after previous temporal lobectomy: Report of cases and review

INTRODUCTION

Anterior temporal lobectomy (LTA) is a surgical procedure commonly used for the treatment of temporal lobe epilepsy refractory to medical management, with high success rates in the control of seizures. However, an important association with psychiatric illnesses has been described that can alter the postoperative outcome in these patients.

METHODS

A series of 2 cases of patients who, despite successful crisis control, developed psychiatric complications in the postoperative period of anterior temporal lobectomy.

RESULTS

The cases included a male patient with no history of previous mental illness, who developed a major depressive episode in the postoperative period, and a female patient with previous psychosis who presented as a surgical complication exacerbation of psychosis, diagnosed with paranoid schizophrenia.

CONCLUSIONS

Psychiatric disorders can occur in postoperative temporal lobe epilepsy patients with or without a history of mental illness. The most frequent alterations reported are depression, anxiety, psychosis and personality disorders. The inclusion of psychiatric evaluations in the pre- and post-surgical protocols can lead to an improvement in the prognosis of the neurological and mental outcomes of the patients undergoing the intervention.

Structural and functional reorganization of contralateral hippocampus after temporal lobe epilepsy surgery

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Postoperative changes of contralateral hippocampus in temporal lobe epilepsy.

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No obvious hippocampal volume change was observed after successful surgery.

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Surgical manipulation may lead to a transient functional connectivity reduction.

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Increased functional connectivity mostly involved bilateral frontal regions.

Objective

To explore the structural and functional reorganization of contralateral hippocampus in patients with unilateral mesial temporal lobe epilepsy (mTLE) who achieved seizure-freedom after anterior temporal lobectomy (ATL).

Methods

We obtained high-resolution structural MRI and resting-state functional MRI data in 28 unilateral mTLE patients and 29 healthy controls. Patients were scanned before and three and 24 months after surgery while controls were scanned only once. Hippocampal gray matter volume (GMV) and functional connectivity (FC) were assessed.

Results

No obvious GMV changes were observed in contralateral hippocampus before and after successful surgery. Before surgery, ipsilateral hippocampus showed increased FC with ipsilateral insula (INS) and temporoparietal junction (TPJ), but decreased FC with widespread bilateral regions, as well as contralateral hippocampus. After successful ATL, contralateral hippocampus showed: (1) decreased FC with ipsilateral INS at three months follow-up, without further changes; (2) decreased FC with ipsilateral TPJ, postcentral gyrus and rolandic operculum at three months, with an obvious increase at 24 months follow-up; (3) increased FC with bilateral medial prefrontal cortex (MPFC) and superior frontal gyrus (SFG) at three months follow-up, without further changes.

Conclusions

Successful ATL may not lead to an obvious structural reorganization in contralateral hippocampus. Surgical manipulation may lead to a transient FC reduction of contralateral hippocampus. Increased FC between contralateral hippocampus and bilateral MPFC and SFG may be related to postoperative functional remodeling.

Surgical treatment of nonlesional temporal lobe epilepsy

PURPOSE

One-third of the patients with drug-resistant temporal lobe epilepsy (TLE) have a normal MRI, but there are only a few studies regarding the surgical outcomes and the efficacy of anterior temporal lobectomy (ATL) in patients with nonlesional TLE. The objective of this study is to evaluate the surgical outcomes and efficacy of ATL in patients with nonlesional TLE.

METHODS

We included 77 consecutive patients without MRI-identifiable lesions who had undergone surgical resection for drug-resistant TLE. We performed univariate and multivariate logistic regression analyses to identify the predictors of surgical outcomes, and the efficacy of ATL in patients with nonlesional TLE.

RESULTS

More than two-thirds of patients (51/76, 67.3 %) had achieved seizure freedom at the last follow-up. Presence of oroalimentary automatism, localized hypometabolism in FDG-PET, and concordant results in presurgical evaluations were associated with better surgical outcomes. Only 15 out of 77 patients (19.2 %) with nonlesional TLE were treated with ATL, and the surgically resected areas were located within the resection margin of ATL in one-third of the patients (26/77, 33.8 %). Patients with auras suggesting neocortical ictal onset and lateralizing semiological features had a higher chance that their potentially epileptogenic areas were located beyond or outside the resection margin of ATL.

CONCLUSION

Our study showed that the potentially epileptogenic areas were located beyond or outside the margin of the ATL in nearly two-thirds of the patients. Several clinical factors may be useful in predicting the location of an epileptogenic area, which can help optimize a surgical strategy in these patients.

Initial delta and delayed theta/alpha pattern in the temporal region on ictal EEG suggests purely hippocampal epileptogenicity in patients with mesial temporal lobe epilepsy

OBJECTIVE

To determine whether the ictal scalp EEG findings suggest purely hippocampal epileptogenicity in patients with mesial temporal lobe epilepsy (mTLE) associated with hippocampal sclerosis (HS).

METHODS

Twenty-three patients with mTLE with pathologically confirmed HS were divided into 12 with epileptogenicity only in the hippocampus (HS only group) and 11 with epileptogenicity in both the hippocampus and temporal neocortex or other locations (HS plus group), based on the combination of surgical procedures, postoperative outcome, and pathological findings. Sixteen underwent selective amygdalohippocampectomy (SelAH) and 7 received anterior temporal lobectomy. Ictal scalp EEG findings of 79 focal impaired awareness seizures were compared between the HS only and HS plus groups. We focused on the 1-4 Hz rhythmic delta activity at ictal onset followed by 5-9 Hz rhythmic theta/alpha activity 10-30 s after the onset in the temporal region.

RESULTS

The initial delta and delayed theta/alpha (ID-DT) pattern was observed in 8 of 12 patients in the HS only group, but in none of 11 patients in the HS plus group (p < 0.01).

CONCLUSIONS

ID-DT pattern on ictal EEG suggests purely hippocampal epileptogenicity in mTLE with HS.

SIGNIFICANCE

Patients with the ID-DT pattern are likely to become seizure-free after SelAH.

Assessing the connectional anatomy of superior and lateral surgical approaches for medial temporal lobe epilepsy

The most common approaches in the treatment of epilepsy, the trans-sylvian selective amygdalohippocampectomy (SAH) and the anterior temporal lobe resection (ATLR) reach the medial temporal lobe through different surgical routes. Our aim was to delineate the white matter (WM) fiber tracts at risk in relation to trans-sylvian SAH and ATLR by defining each fascicle en route to medial temporal lobe during each approach. ATLR and trans-sylvian SAH were performedand related WM tracts en route to medial temporal region were presented in relation to the relevant approaches and surrounding neurovascular structures. The WM tracts most likely to be disrupted during trans-sylvian SAH along the roof of the temporal horn were the UF - and less commonly IFOF - at the layer of the external capsule, anterior commissure, anterior bend of optic radiations, and sublenticular internal capsule. Amygdaloid projections to the claustrum, putamen and globus pallidus, the tail of caudate and the peduncle of the lentiform nucleus were also in close proximity to the resection cavity. Fiber tracts most likely to be impaired during ATLR included the UF, ILF, IFOF, anterior commissure, optic radiations, and, less likely, the vertical ventral segment of the arcuate fascicle. Both ATLR and trans-sylvian SAH carry the risk of injury to WM pathways, which may result in unpredictable functional loss. A detailed 3-D knowledge of the related connectional anatomy will help subside neurocognitive, neuroophtalmologic, neurolinguistic complications of epilepsy surgery, providing an opportunity to tailor the surgery according to patient's unique connectional and functional anatomy.

Psychiatric Alterations after Previous Temporal Lobectomy: Report of Cases and Review

INTRODUCTION

Anterior temporal lobectomy (LTA) is a surgical procedure commonly used for the treatment of temporal lobe epilepsy refractory to medical management, with high success rates in the control of seizures. However, an important association with psychiatric illnesses has been described that can alter the postoperative outcome in these patients.

METHODS

A series of 2 cases of patients who, despite successful crisis control, developed psychiatric complications in the postoperative period of anterior temporal lobectomy.

RESULTS

The cases included a male patient with no history of previous mental illness, who developed a major depressive episode in the postoperative period, and a female patient with previous psychosis who presented as a surgical complication exacerbation of psychosis, diagnosed with paranoid schizophrenia.

CONCLUSIONS

Psychiatric disorders can occur in postoperative temporal lobe epilepsy patients with or without a history of mental illness. The most frequent alterations reported are depression, anxiety, psychosis and personality disorders. The inclusion of psychiatric evaluations in the pre- and post-surgical protocols can lead to an improvement in the prognosis of the neurological and mental outcomes of the patients undergoing the intervention.

Safety metric profiling in surgery for temporal glioblastoma: lobectomy as a supra-total resection regime preserves perioperative standard quality rates

Introduction

Supra-total resection in terms of anterior temporal lobectomy (ATL) has gained growing attention with regard to superior long-term disease control for temporal-located glioblastoma. However, aggressive onco-surgical approaches—geared beyond conventional gross total resections (GTR)—may be associated with peri- and postoperative unfavorable events which significantly worsen initial favorable postoperative outcome. In the current study we analyzed our institutional database with regard to patient safety indicators (PSIs), hospital-acquired conditions (HACs) and specific cranial surgery-related complications (CSC) as high standard quality metric profiles in patients that had undergone surgery for temporal glioblastoma.

Methods

Between 2012 and 2018, 61 patients with temporal glioblastoma underwent GTR or temporal lobectomy at the authors’ institution. Both groups of differing resection modalities were analyzed with regard to the incidence of PSIs, HACs and CSCs.

Results

Overall, we found 6 PSI and 2 HAC events. Postoperative hemorrhage (3 out of 61 patients; 5%) and catheter-associated urinary tract infection (2 out 61 patients; 3%) were identified as the most frequent PSIs and HACs. PSIs were present in 1 out of 41 patients (5%) for the temporal GTR and 2 out of 20 patients for the lobectomy group (p = 1.0). Respective rates for PSIs were 5 of 41 (12%) and 1 of 20 (5%) (p = 0.7). Further, CSCs did not yield significant differences between these two resection modalities (p = 1.0).

Conclusion

With regard to ATL and GTR as differing onco-surgical approaches these data suggest ATL in terms of an aggressive supra-total resection strategy to preserve perioperative standard safety metric profiles.

A patient-centered approach to understanding long-term psychosocial adjustment and meaning-making, 15 to 20 years after epilepsy surgery

OBJECTIVE

Different psychosocial trajectories have been identified following treatment with epilepsy surgery, as patients adjust to possible changes in seizure frequency and the subsequent impact on their psychosocial functioning. Qualitative research has been key to understanding this adjustment process, particularly in the short-term (2-5 years). Currently, however, there is a lack of qualitative research examining longer-term (>15 years) outcomes, precluding the same rich, detailed understanding of longer-term psychosocial outcomes. Using a grounded theory approach, we explored how patients reflected on and made sense of their adjustment trajectories, 15 to 20 years after surgery. This included the impact of surgery on their sense of self and broader psychosocial functioning.

METHODS

We recruited 40 adult patients who had undergone anterior temporal lobectomy (ATL) 15 to 20 years ago (24 females; 26 left-sided). Median age at habitual seizure onset was 9.7 years (Interquartile range; IQR = 13.8), and at surgery was 31 years (IQR = 12). Median length of follow-up was 18.4 years (IQR = 4.3). Comprehensive one-on-one interviews (median time = 86 min, IQR = 28) were used to elicit patient experiences of their surgery and subsequent psychosocial outcomes. Data were analyzed using a grounded theory inductive-deductive process.

RESULTS

Patient narratives revealed a common process of psychosocial change and meaning-making triggered by surgery, which was often perceived as a major turning point in life. Patients reflected on moving through an early postsurgical period (<5 years) of upheaval and psychological disequilibrium. While this period was often remembered as stressful, difficulties were softened and/or reframed in hindsight. Through this process of reframing and meaning-making, patients were able to reestablish equilibrium and a sense of normality. Differences were evident in how patients navigated the process of meaning-making, and the extent to which they felt surgery had changed their self-identity.

DISCUSSION

We propose a model of postsurgical meaning-making, evident in the narratives of patients who have undergone ATL, providing a new perspective on long-term psychosocial outcomes. This model contributes to our understanding of patient well-being and quality of life, by acknowledging the active role that patients play in seeking to create their own sense of normality after epilepsy surgery.

Mesial temporal lobe epilepsy: A West Indian Neurosurgical Experience

INTRODUCTION

We sought to highlight a case of refractory mesial temporal lobe epilepsy managed via an anterior temporal lobectomy. To our knowledge, this is the first of its kind to be performed and published in the English-speaking Caribbean.

PRESENTATION OF CASE

A 44-year-old female, known seizure disorder for 25 years was referred to the outpatient clinic. Several trials of varying anti-epileptic drugs failed to provide remittance of her frequent partial seizures over the last two decades. Magnetic resonance imaging displayed asymmetry of the hippocampus, with a prominent right temporal horn of lateral ventricle, in keeping with right anteromesial temporal lobe sclerosis. She underwent a right anterior temporal lobectomy after exhaustive counselling; with the guidance of a multidisciplinary team. The post-operative period was uneventful and currently, the patient has been seizure-free since operation.

DISCUSSION

Drug resistant epilepsy is defined as failure of adequate trials of two tolerated, appropriately chosen and used anti-epileptic drug schedules to attain sustained seizure freedom. Medical management of mesial temporal lobe epilepsy has a relatively poor long-term outcome, with 30 % of patients falling into the category of pharmaco-resistant.

CONCLUSION

Surgical management of these cases have been proven to be a safe and effective alternative but is currently greatly underutilized. In our literature review, we present the first published case of epilepsy surgery in the English-speaking Caribbean for temporal lobe epilepsy.

Magnetoencephalography as a Prognostic Tool in Patients with Medically Intractable Temporal Lobe Epilepsy

BACKGROUND

Most surgical treatments for medically intractable temporal lobe epilepsy are helpful. When a patient has persistent symptoms after surgery, there are no tests that accurately predict whether a patient will have remnant epileptic foci. The aim of this study was to evaluate the usefulness of magnetoencephalography (MEG) as a prognostic tool in patients with temporal lobe epilepsy.

METHODS

From July 2012 to July 2016, 21 patients underwent preoperative and postoperative MEG at our center. Postoperative MEG was performed within 2 weeks after surgery. We analyzed MEG by estimating the time-frequency component of the signal to define gamma oscillations (GOs), which are an indicator of epileptogenic foci. We analyzed the relationship between GOs on MEG and surgical outcomes.

RESULTS

Mean follow-up period was 28.3 months (range, 13-44 months). At the last follow-up visit, patients were divided into 2 groups according to surgical outcome. All patients showed spike waves and GOs on preoperative electroencephalography and MEG. In the seizure control group (16 patients), spike waves (2 patients) and GOs (2 patients) were seen postoperatively despite absence of symptoms. In the recurrent seizure group (5 patients), whereas 3 patients showed spike waves, all 5 patients showed GOs on MEG postoperatively. There was a significant association between presence of GOs on postoperative MEG and surgical outcome (P = 0.01).

CONCLUSIONS

MEG can provide valuable postsurgical information on epileptic foci in patients with recurrent symptoms; GOs on postoperative MEG were especially correlated with epileptic recurrence. Our data show that GOs on postoperative MEG may have prognostic value.

Different patterns of white matter changes after successful surgery of mesial temporal lobe epilepsy

Objectives

To explore the dynamic changes of white matters following anterior temporal lobectomy (ATL) in mesial temporal lobe epilepsy (MTLE) patients who achieved seizure-free at two-year follow-up.

Methods

Diffusion tensor imaging (DTI) was obtained in ten MTLE patients at five serial time points: before surgery, three months, six months, 12 months and 24 months after surgery, as well as in 11 age- and sex-matched healthy controls at one time point. Regions with significant postoperative fractional anisotropy (FA) changes and their dynamic changes were confirmed by comparing all preoperative and postoperative data using Tract-Based Spatial Statistics (TBSS).

Results

After successful ATL, significant FA changes were found in widespread ipsilateral and contralateral white matter regions (P <.05, FWE correction). Ipsilateral external capsule, cingulum, superior corona radiate, body of corpus callosum, inferior longitudinal fasciculus, optic radiation and contralateral inferior cerebellar peduncle, inferior longitudinal fasciculus showed significant FA decrease at three months after surgery, without further changes. Ipsilateral superior cerebellar peduncle and contralateral corpus callosum, anterior corona radiate, external capsule, optic radiation showed significant FA decrease at three months follow up but increase later. Ipsilateral cerebral peduncle and contralateral middle cerebellar peduncle showed significant FA decrease at three months follow up, with further decrease after that. While ipsilateral posterior limb of internal capsule, retrolenticular part of internal capsule and contralateral posterior corona radiate showed significant FA increase after surgery.

Conclusions

FA changes after successful ATL presented as four distinct patterns, reflecting different structural adaptions following epilepsy surgery. Some FA increases indicated the reversibility of preoperative diffusion abnormalities and the possibility of structural reorganization, especially in the contralateral hemisphere.

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Widespread white matter abnormalities existed in mesial temporal lobe epilepsy.

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We explored longitudinal DTI changes at five serial time points before and after anterior temporal lobectomy.

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We found four distinct patterns of diffusion changes, reflecting different structural adaptions following epilepsy surgery.

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Structural reorganization did occur after surgery, especially in contralateral hemisphere.

Brain network alterations of mesial temporal lobe epilepsy with cognitive dysfunction following anterior temporal lobectomy

The aims of this study were to investigate the brain network connectivity alterations of intractable unilateral mesial temporal lobe epilepsy (MTLE) with cognitive dysfunction before and after anterior temporal lobectomy (ATL) using resting-state functional magnetic resonance imaging (rs-fMRI) study and to further observe the correlation between the brain network connectivity with cognitive performance. Fourteen patients with unilateral left MTLE before and after ATL were compared with thirty healthy controls (HCs) on functional connectivity (FC) between resting-state networks (RSNs). The correlation between the neuropsychological tests of patients and abnormal FC was further investigated. When compared with the HCs, patients before surgery showed significantly changed FC between special RSNs. No difference of FC was found between each RSN when patients were compared with the HCs after surgery. Compared with patients before surgery, patients after surgery showed significantly decreased FC between RSNs. Abnormal FC between RSNs significantly correlated with Montreal Cognitive Assessment (MoCA) scores. Our study suggested that dynamic alterations of RSN after ATL in unilateral MTLE may be closely related with seizure generating. However, unchanged FC between RSN before and after ATL may be closely related with cognitive performance. The present findings may help us understand the feature of brain network alterations in patients with left MTLE who became seizure-free following ATL.

Memory loss and memory reorganization patterns in temporal lobe epilepsy patients undergoing anterior temporal lobe resection, as demonstrated by pre-versus post-operative functional MRI

This study was aimed to longitudinally assess memory function and whole-brain memory circuit reorganization in patients with temporal lobe epilepsy (TLE) by comparing activation potentials before versus after anterior temporal lobe (ATL) resection. Nineteen patients with medically-intractable TLE (10 left TLE, 9 right TLE) and 15 healthy controls were enrolled. Group analyses were conducted pre- and post-ATL of a novelty complex scene-encoding paradigm comparing areas of blood oxygen-level-dependent (BOLD) signal activations on functional magnetic resonance imaging (fMRI). None of the pre-operative patient characteristics we studied predicted the extent of pre- to post-operative memory loss. On fMRI, extra-temporal activations were detected pre-operatively in both LTLE and RTLE, particularly in the frontal lobe. Greater activations also were noted in the contralateral hippocampus and parahippocampus in both groups. Performing within-subject comparisons, post-op relative to pre-op, pronounced ipsilateral activations were identified in the left parahippocampal gyrus in LTLE, versus the right middle temporal gyrus in RTLE patients. Memory function was impaired pre-operatively but declined after ATL resection in both RTLE and LTLE patients. Post-operative fMRI results indicate possible functional adaptations to ATL loss, primarily occurring within the left parahippocampal gyrus versus right middle temporal gyrus in LTLE versus RTLE patients, respectively.

The surgical outcome of patients with bilateral temporal lobe epilepsy

OBJECTIVES

The purpose of this study is to explore the surgical outcome of unilateral anterior temporal lobectomy (ATL) for patients with bilateral temporal lobe epilepsy (BTLE).

METHODS

We retrospectively reviewed the data of patients who were diagnosed with BTLE by scalp electroencephalogram (EEG) and underwent ATL from 2001 to 2015. In addition, 80 patients were randomly selected as a control group.

RESULTS

One hundred seventeen patients were included in this study and were divided into four groups by intracranial recordings as follows: 78 patients with unilateral seizure onset (Group 1), 13 patients with lateralizable dominant seizure onset (Group 2), 14 patients with lateralizable neuroimaging abnormalities (Group 3), and 12 patients without lateralizable dominant seizure onset or neuroimaging abnormalities (Group 4). The 12 patients in Group 4 declined surgical resection, whereas the remaining 105 patients received ATL, and 93 of them were followed up for more than 1 year after surgery. At the 1-, 2-, and 3-year follow-ups the percentage of patients who were seizure free was 52.9%, 56.5%, and 58.9%, respectively. For the mean postoperative efficacy, there was a statistical difference in patients who were seizure free either between Group 1 + Group 2 + Group 3 and the control group (44.1% vs. 67.5%, p = 0.002), or between Group 1 and the control group (48.5% vs. 67.5%, p = 0.019), or between Group 2 + Group 3 and the control group (32.0% vs. 67.5%, p = 0.002). However, the difference was significant only at the first year follow-up, and there was no significant difference afterward.

SIGNIFICANCE

Although the surgical outcome of patients with BTLE is not as good as that of patients with unilateral TLE in short-term follow-up, quite a portion of these patients could benefit from unilateral temporal lobe resection in the long term.

Simultaneous Treatment of Epilepsy and Secondary Dystonia After Anterior Temporal Lobectomy and Amygdalohippocampectomy

BACKGROUND

The relationship between temporal lobe epilepsy and focal limb dystonia is a well-recognized phenomenon, yet its pathogenesis and anatomic foundation are not well understood. Here, we describe 2 patients with refractory focal epilepsy and contralateral focal limb dystonia whose seizures and dystonic symptoms simultaneously resolved after anterior temporal lobectomy and amygdalohippocampectomy.

CASE DESCRIPTION

We identified 2 patients within the Mount Sinai Health system with improvement in dystonia after medial temporal lobectomy. Retrospective chart reviews for the clinical history were performed. Patient 1 suffered a traumatic injury of the right temporal lobe, developing left hemidystonia and epilepsy. He received a right amygdala-hippocampectomy, which resolved both. Patient 2 has a history of right temporal glioma resection complicated by an infarct, resulting in left hemidystonia and epilepsy. He received a right medial temporal resection, which nearly resolved both.

CONCLUSION

Our cases demonstrate a medial temporal-basal ganglia network dysfunction in dystonia-epilepsy that was modulated and cured by resective surgery. We hypothesize that the mechanisms behind these observed phenomena were due to a pathologic connectivity of the basal ganglia and amygdala-hippocampus. To our knowledge, these are the first reported cases of dystonia and concomitant epilepsy resolving with temporal lobectomy and provide valuable prognostic information for similarly affected patients.

Changes in sleep patterns after vagus nerve stimulation, deep brain stimulation or epilepsy surgery: Systematic review of the literature

PURPOSE

Perform a systematic review of the literature on the effects of vagus nerve stimulation (VNS), deep brain stimulation (DBS) and epilepsy surgery in subjective and objective sleep parameters.

METHODS

We performed a literature search in the main medical databases: Medline, Embase, Cochrane, DARE and LILACS, looking for studies that evaluated the effects of VNS, DBS or epilepsy surgery on sleep parameters. In all, 36 studies, coming from 11 countries, including reviews, cohort studies, case series and case reports were included.

RESULTS

VNS induces sleep apnoea dependent of the stimulation variables. This condition can be reverted modifying these settings. Surgical procedures for epilepsy cause an improvement in objective and subjective sleep parameters that depend on the success of the procedure evaluated through ictal frequency control. There is evidence that non-pharmacologic treatment of epilepsy has different effects on sleep patterns.

CONCLUSION

It is advisable to include objective and subjective sleep parameters in the initial evaluation and follow-up of patients considered for invasive procedures for epilepsy control, especially with VNS due to the risk of sleep apnoea. More high quality studies are needed.

Psychiatric lifetime diagnoses are associated with a reduced chance of seizure freedom after temporal lobe surgery

OBJECTIVE

To examine whether psychiatric comorbidity is a predictor of long-term seizure outcome following temporal lobe epilepsy surgery.

METHODS

A sample of 434 adult patients who received temporal lobe resection to treat epilepsy between 1991 and 2009 and were psychiatrically assessed before surgery were followed for 2 years to assess seizure outcome. Stepwise multivariate logistic regression analyses were used to assess the impact of psychiatric variables on complete seizure freedom (Engel class IA), and freedom from disabling seizures (Engel class I). Lifetime histories of three psychiatric syndromes (PS: psychosis; depression; other) and five personality disorders (PD: DSM-IV Clusters A, B, and C; organic personality disorder; other) were considered as predictors, complemented by age at onset, duration of epilepsy, type of lesion (mesiotemporal sclerosis vs. other), and year of surgery.

RESULTS

Seizure-freedom rates were significantly higher (p < 0.001) in patients with no history of PS or PD (N = 138; Engel class IA: 61.6%; Engel class I: 87.7%) than in those with any PS or PD (N = 296; Engel class IA: 39.5%; Engel class I: 58.8%). Particularly low seizure-freedom rates were found in patients with a diagnosis of psychosis (N = 32, Engel class IA: 21.9%; Engel class I: 40.6%), organic PD (N = 48, Engel class IA: 25.0%; Engel class I: 35.4%) or a double diagnosis of PS plus PD (N = 97; Engel class IA: 27.8%; Engel class I: 45.5%). No other variables emerged as significant risk factors in multivariate logistic regression analyses.

SIGNIFICANCE

Patients with and without psychiatric comorbidities can benefit from temporal lobe epilepsy surgery; however, psychiatric comorbidities are negatively associated with postoperative seizure-freedom rates. Surgical outcome is related to the type and extent of preoperative psychiatric morbidity, which underscores the prognostic value of presurgical psychiatric evaluation. The data support the argument that there are common pathogenetic mechanisms underlying both epilepsy and psychiatric conditions.

Ictal asystole: A rare cardiac manifestation of temporal lobe epilepsy, treated with epilepsy surgery

Seizures are associated with fascinatingly varied cardiac and autonomic manifestations, of which ictal tachycardia is common, and asystole and bradycardia are rare. Ictal asystole (IA), an often unsought autonomic phenomenon, occurs most commonly with temporal followed by frontal lobe seizures. Prolonged IA may lead to cerebral anoxic ischemia. As the mysteries of sudden unexplained death in epilepsy are unraveled, it is quite possible that the key to it lays within these seizure-induced cardiac rhythm abnormalities. We present a case of a young male with temporal lobe epilepsy due to left mesial temporal sclerosis with prolonged IA, which was successfully managed with epilepsy surgery.

Anterior temporal lobectomy for older adults with mesial temporal sclerosis

OBJECTIVE

To compare postoperative seizure-free survival between older and younger adults.

METHODS

A retrospective cohort of 107 temporal lobe epilepsy patients with a diagnosis of mesial temporal sclerosis (MTS) received anterior temporal lobectomy (ATL) between 1993 and 2014. We divided the lower three quartiles (younger) and top quartile (older, all 47+ years) of patients, then reviewed patient registry and electronic medical records to determine time to first self-reported seizure after ATL, the primary outcome (mean=3.5years of follow-up, SD=3.6). We also assessed Engel classifications, intraoperative and postoperative treatment complications, and social disability. We used Cox proportional hazard models to assess the association between individual traits and time of seizure recurrence.

RESULTS

During follow-up, 35/107 (32.7%) patients had post-operative seizure(s). After adjustment for potential confounders there were no significant differences in the probability of post-operative seizures between the older and younger groups, though we had limited precision (hazard ratio of 0.67 [0.28-1.59]), (p=0.36). There were more treatment complications and disability in older patients (18% vs. 1.3% for any complications, 84.62% vs. 58.23% for driving disability, and 84.6% vs. 60.7% for work disability, p<0.05).

CONCLUSION

Older patients appear to have more complications after ATL, compared with younger patients. Age, however, does not appear to have a large independent association with seizure recurrence.

The role of the temporal pole in modulating primitive auditory memory

Primitive auditory memory (PAM), which is recognized as the early point in the chain of the transient auditory memory system, faithfully maintains raw acoustic fine-structure signals for up to 20-30 milliseconds. The neural mechanisms underlying PAM have not been reported in the literature. Previous anatomical, brain-imaging, and neurophysiological studies have suggested that the temporal pole (TP), part of the parahippocampal region in the transitional area between perirhinal cortex and superior/inferior temporal gyri, is involved in auditory memories. This study investigated whether the TP plays a role in mediating/modulating PAM. The longest interaural interval (the interaural-delay threshold) for detecting a break in interaural correlation (BIC) embedded in interaurally correlated wideband noises was used to indicate the temporal preservation of PAM and examined in both healthy listeners and patients receiving unilateral anterior temporal lobectomy (ATL, centered on the TP) for treating their temporal lobe epilepsy (TLE). The results showed that patients with ATL were still able to detect the BIC even when an interaural interval was introduced, regardless of which ear was the leading one. However, in patient participants, the group-mean interaural-delay threshold for detecting the BIC under the contralateral-ear-leading (relative to the side of ATL) condition was significantly shorter than that under the ipsilateral-ear-leading condition. The results suggest that although the TP is not essential for integrating binaural signals and mediating the PAM, it plays a role in top-down modulating the PAM of raw acoustic fine-structure signals from the contralateral ear.

Neurocognitive outcome following stereotactic laser ablation in two patients with MRI-/PET+ mTLE

The most effective treatment for drug-resistant seizures associated with mesial temporal lobe epilepsy (mTLE) is surgical resection. Neurocognitive sequelae may occur and are especially likely to occur after left temporal lobectomy. Smaller resections observed with selective amygdalohippocampectomy have resulted in a more favorable neurocognitive outcome in some cases when compared to standard anterior temporal lobectomy. Specifically, MRI-guided interstitial laser thermal ablation (MRgLITT) uses a superselective stereotactic amygdalohippocampotomy that has been reported to preserve object recognition and naming abilities compared with standard temporal lobe resection. We report two patients with drug-resistant mTLE and a normal high-resolution 3-T brain MRI who underwent neuropsychological assessment pre- and postleft temporal MRgLITT. Both patients demonstrated preserved visual naming ability following surgery. Semantic verbal fluency declined after surgery, but the magnitude of decline did not reach the statistical threshold for reliable change. Both patients demonstrated statistically significant and clinically meaningful declines in memory, but abilities across other nonmemory neurocognitive domains (i.e., visuospatial ability, attention) were preserved.

Anterior temporal lobectomy

BACKGROUND

Anterior temporal lobectomy is the most established neurosurgical procedure for temporal lobe epilepsy. Here we describe this technique.

METHOD

A temporal craniotomy is performed flush with the middle fossa and exposing the Sylvian fissure. The posterior extent of resection is determined as 4.5 cm in the dominant temporal lobe and 5.5 cm in the nondominant one. The first stage consists of removing the lateral neocortex and part of the fusiform gyrus, parallel to the Sylvian fissure, while keeping the temporal horn as the medial limit in the coronal plane. Then, the amygdala, uncus, fimbriae, hippocampus and collateral eminence are identified, transected and resected with the parahippocampal gyrus to complete the procedure.

CONCLUSION

Knowledge of the temporomesial anatomy, including neurovascular structures around the brainstem, is essential to keep this procedure safe and effective.

Different effects of anterior temporal lobectomy and selective amygdalohippocampectomy on verbal memory performance of patients with epilepsy

The advantage of selective amygdalohippocampectomy (SAH) over anterior temporal lobectomy (ATL) for the treatment of temporal lobe epilepsy (TLE) remains controversial. Because ATL is more extensive and involves the lateral and medial parts of the temporal lobe, it may be predicted that its impact on memory is more important than SAH, which involves resection of medial temporal structures only. However, several studies do not support this assumption. Possible explanations include task-specific factors such as the extent of semantic and syntactic information to be memorized and failure to control for main confounders. We compared preoperative vs. postoperative memory performance in 13 patients with SAH with 26 patients who underwent ATL matched on side of surgery, IQ, age at seizure onset, and age at surgery. Memory function was assessed using the Logical Memory subtest from the Wechsler Memory Scales - 3rd edition (LM-WMS), the Rey Auditory Verbal Learning Test (RAVLT), the Digit Span subtest from the Wechsler Adult Intelligence Scale, and the Rey-Osterrieth Complex Figure Test. Repeated measures analyses of variance revealed opposite effects of SAH and ATL on the two verbal learning memory tests. On the immediate recall trial of the LM-WMS, performance deteriorated after ATL in comparison with that after SAH. By contrast, on the delayed recognition trial of the RAVLT, performance deteriorated after SAH compared with that after ATL. However, additional analyses revealed that the latter finding was only observed when surgery was conducted in the right hemisphere. No interaction effects were found on other memory outcomes. The results are congruent with the view that tasks involving rich semantic content and syntactical structure are more sensitive to the effects of lateral temporal cortex resection as compared with mesiotemporal resection. The findings highlight the importance of task selection in the assessment of memory in patients undergoing TLE surgery.

The Role of Stereotactic Laser Amygdalohippocampotomy in Mesial Temporal Lobe Epilepsy

Stereotactic laser amygdalohippocampotomy (SLAH) uses laser interstitial thermal therapy guided by magnetic resonance thermography. This novel intervention can achieve seizure freedom while minimizing collateral damage compared to traditional open surgery, in patients with mesial temporal lobe epilepsy. An algorithm is presented to guide treatment decisions for initial and repeat procedures in patients with and without mesial temporal sclerosis. SLAH may improve access by medication-refractory patients to effective surgical treatments and thereby decrease medical complications, increase productivity, and minimize socioeconomic consequences in patients with chronic epilepsy.

Organic Mood Disorder Following Left Anterior Temporal Lobectomy with Amygdalohippocampectomy

One third of patients with antiepileptic-resistant temporal lobe epilepsy (TLE) will have to undergo surgery for a better seizure control. Anterior temporal lobectomy (ATL) is done for mesial temporal sclerosis that is the most common histopathological lesion associated with TLE. Psychiatric manifestations following ATL are not uncommon with depressive symptoms more common with left ATL and manic symptoms following right ATL. Mr. A is a 42-year-old left cerebral dominant (Confirmed by WADA test) male with no past history of psychiatric illness who had undergone anterior temporal lobectomy with amygdalohippocampectomy. He started having manic episodes post operatively which subsided with antipsychotics. He had multiple such episodes over the next 13 years with minimal inter episodic symptoms. This is a rare instance of manic symptoms following left-sided ATL that emphasizes the need for better understanding of the cerebral laterality of affective symptoms.

Memory outcome following left anterior temporal lobectomy in patients with a failed Wada test

PURPOSE

This study aimed to compare the memory outcome following left anterior temporal lobectomy (ATL) between patients with a failed Wada test and patients who passed the Wada test.

METHODS

From 1996 to 2002, we performed the Wada test on all patients with unilateral left mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) and concordant electroclinical data before ATL. We used a 12-item recognition paradigm for memory testing and awarded a score of +1 for each correct response and -0.5 for each incorrect response. No patient was denied surgery on the basis of Wada scores. We assessed cognitive and memory functions using the Wechsler Adult Intelligence Scale and the Wechsler Memory Scale preoperatively and at one year after ATL. We compared the number of patients who showed decline in memory scores, as per the published reliable change indices, between the patients with a failed Wada test and the patients who passed the Wada test.

RESULTS

Out of the 116 eligible patients with left MTLE-HS, 88 underwent bilateral Wada test, while 28 underwent ipsilateral Wada test. None of them developed postoperative amnesia. Approximately, one-third of patients with a failed Wada memory test when the failure was defined as a contralateral score of <4, as an ipsilateral score of >8, and as an asymmetry score of <0. The patients with Wada memory failure had a longer pre-ATL duration of epilepsy (p<0.003). The memory and quality-of-life outcomes did not differ between the group with a failed Wada memory test and the group who passed the Wada memory test. The results remained the same when analyses were repeated at various other cutoff points.

CONCLUSION

The patients with left MTLE-HS with concordant electroclinical, MRI, and neuropsychological data should not be denied ATL solely on the basis of Wada memory test results.

Presurgery resting-state local graph-theory measures predict neurocognitive outcomes after brain surgery in temporal lobe epilepsy

OBJECTIVE

This study determined the ability of resting-state functional connectivity (rsFC) graph-theory measures to predict neurocognitive status postsurgery in patients with temporal lobe epilepsy (TLE) who underwent anterior temporal lobectomy (ATL).

METHODS

A presurgical resting-state functional magnetic resonance imaging (fMRI) condition was collected in 16 left and 16 right TLE patients who underwent ATL. In addition, patients received neuropsychological testing pre- and postsurgery in verbal and nonverbal episodic memory, language, working memory, and attention domains. Regarding the functional data, we investigated three graph-theory properties (local efficiency, distance, and participation), measuring segregation, integration and centrality, respectively. These measures were only computed in regions of functional relevance to the ictal pathology, or the cognitive domain. Linear regression analyses were computed to predict the change in each neurocognitive domain.

RESULTS

Our analyses revealed that cognitive outcome was successfully predicted with at least 68% of the variance explained in each model, for both TLE groups. The only model not significantly predictive involved nonverbal episodic memory outcome in right TLE. Measures involving the healthy hippocampus were the most common among the predictors, suggesting that enhanced integration of this structure with the rest of the brain may improve cognitive outcomes. Regardless of TLE group, left inferior frontal regions were the best predictors of language outcome. Working memory outcome was predicted mostly by right-sided regions, in both groups. Overall, the results indicated our integration measure was the most predictive of neurocognitive outcome. In contrast, our segregation measure was the least predictive.

SIGNIFICANCE

This study provides evidence that presurgery rsFC measures may help determine neurocognitive outcomes following ATL. The results have implications for refining our understanding of compensatory reorganization and predicting cognitive outcome after ATL. The results are encouraging with regard to the clinical relevance of using graph-theory measures in presurgical algorithms in the setting of TLE.

Diffusion tensor imaging tractography of Meyer's loop in planning resective surgery for drug-resistant temporal lobe epilepsy

PURPOSE

Whether Meyer's loop (ML) tracking using diffusion tensor imaging tractography (DTIT) can be utilized to avoid post-operative visual field deficits (VFD) after anterior temporal lobectomy (ATL) for drug-resistant temporal lobe epilepsy (TLE) using a large cohort of controls and patients. Also, we wanted to create a normative atlas of ML in normal population.

METHODS

DTIT was used to study ML in 75 healthy subjects and 25 patients with and without VFD following ATL. 1.5T MRI echo-planar DTI sequences with DTI data were processed in Nordic ICE using a probabilistic method; a multiple region of interest technique was used for reconstruction of optic radiation trajectory. Visual fields were assessed in patients pre- and post-operatively.

RESULTS

Results of ANOVA showed that the left ML-TP distance was less than right across all groups (p = 0.01). The average distance of ML from left temporal pole was 37.44 ± 4.7 mm (range: 32.2-46.6 mm) and from right temporal pole 39.08 ± 4.9 mm (range: 34.3-49.7 mm). Average distance of left and right temporal pole to tip of temporal horn was 28.32 ± 2.03 mm (range: 26.4-32.8 mm) and was 28.92 ± 2.09 mm, respectively (range: 25.9-33.3 mm). If the anterior limit of the Meyer's loop was ≤38 mm on the right and ≤35 mm on the left from the temporal pole, they are at a greater risk of developing VFDs.

CONCLUSIONS

DTIT is a novel technique to delineate ML and plays an important role in planning surgical resection in TLE to predict post-operative visual performance and disability.

Weighing the value of memory loss in the surgical evaluation of left temporal lobe epilepsy: a decision analysis

OBJECTIVES

Anterior temporal lobectomy is curative for many patients with disabling medically refractory temporal lobe epilepsy, but carries an inherent risk of disabling verbal memory loss. Although accurate prediction of iatrogenic memory loss is becoming increasingly possible, it remains unclear how much weight such predictions should have in surgical decision making. Here we aim to create a framework that facilitates a systematic and integrated assessment of the relative risks and benefits of surgery versus medical management for patients with left temporal lobe epilepsy.

METHODS

We constructed a Markov decision model to evaluate the probabilistic outcomes and associated health utilities associated with choosing to undergo a left anterior temporal lobectomy versus continuing with medical management for patients with medically refractory left temporal lobe epilepsy. Three base-cases were considered, representing a spectrum of surgical candidates encountered in practice, with varying degrees of epilepsy-related disability and potential for decreased quality of life in response to post-surgical verbal memory deficits.

RESULTS

For patients with moderately severe seizures and moderate risk of verbal memory loss, medical management was the preferred decision, with increased quality-adjusted life expectancy. However, the preferred choice was sensitive to clinically meaningful changes in several parameters, including quality of life impact of verbal memory decline, quality of life with seizures, mortality rate with medical management, probability of remission following surgery, and probability of remission with medical management.

SIGNIFICANCE

Our decision model suggests that for patients with left temporal lobe epilepsy, quantitative assessment of risk and benefit should guide recommendation of therapy. In particular, risk for and potential impact of verbal memory decline should be carefully weighed against the degree of disability conferred by continued seizures on a patient-by-patient basis.

Application of diffusion tensor imaging and tractography of the optic radiation in anterior temporal lobe resection for epilepsy: a systematic review

BACKGROUND

Approximately 50-100% of patients with temporal lobe epilepsy undergoing anterior temporal lobe resection (ATLR) will suffer a postoperative visual field defect (VFD) due to disruption of the optic radiation (OpR).

OBJECTIVE

We conducted a systematic review of the literature to examine the role of DTI and tractography in ATLR and its potential in reducing the incidence of postoperative VFD.

METHODS

We conducted an electronic literature search using PubMed, Embase, Web of Science and BMJ case report databases. Eligibility for study inclusion was determined on abstract screening using the following criteria: the study must have been (1) an original investigation or case report in humans; (2) investigating the OpR with DTI in cases of ATLR in temporal lobe epilepsy; (3) investigating postoperative VFD. All forms of ATLR and ways of assessing VFD were included to reflect clinical practice.

RESULTS

13 studies (four case reports, eight prospective observational studies, one prospective comparative trial) were included in the review, 179 (mean±SD, 13.8±12.6; range, 1-48) subjects were investigated using DTI. The time of postoperative VFD measurement differed between the detected studies, ranging from two weeks to nine years following ATLR. A modest number of studies and insufficient statistical homogeneity precluded meta-analysis. However, DTI methods were consistently accurate at quantifying and predicting postoperative damage to the OpR. These methods revealed a correlation between the extent of OpR damage and the severity of postoperative VFD. The first and only trial with 15 subjects compared to 23 controls reported that using intraoperative tractography in ATLR significantly reduces the occurrence of postoperative VFD on comparison to conventional surgical planning.

CONCLUSIONS

DTI shows potential to be an effective method used in planning ATLR. Findings from a single modest sized study suggest that tractography may be employed as part of intraoperative navigation techniques in order to avoid injury to the OpR. Further research needs to be conducted to ensure the applicability and effectiveness of this technology before implementation in routine clinical practice.

Major vault protein (MVP) gene polymorphisms and drug resistance in mesial temporal lobe epilepsy with hippocampal sclerosis

The human major vault protein (MVP) has been implicated in the development of drug resistance in cancer cells. Over expression of MVP has also been reported in brain tissue samples from antiepileptic drug (AED)-resistant human focal epilepsies. To investigate the relationship between single nucleotide polymorphisms (SNPs) involving the MVP gene and AED-resistance, we compared the distribution of three SNPs in the MVP gene, rs4788187, rs3815824 and rs3815823, among 220 patients with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS) (prototype of AED-resistant epilepsy syndrome), 201 patients with juvenile myoclonic epilepsy (JME) (prototype of AED-responsive epilepsy syndrome) and 213 ethnically matched non-epilepsy controls. All the patients and controls were residents of the South Indian state of Kerala for more than three generations. We did not find any significant difference in allele and genotypic frequencies of the studied SNPs between AED-resistant and AED-responsive cohorts, and between AED-resistant and AED-responsive cohorts independently and pooled together when compared with the controls. We conclude that rs4788187, rs3815824, rs3815823 variants of the MVP gene are associated neither with predisposition for epilepsy nor with AED-resistance in the population that we have studied. Our results suggest the need for further research into the link between MVP and AED-resistance.

Microneurosurgical management of temporal lobe epilepsy by amygdalohippocampectomy (AH) plus standard anterior temporal lobectomy (ATL): a report of our initial five cases in Bangladesh

Patient presenting as a case of Temporal Lobe Epilepsy (TLE) are usually resistant to antiepileptic drugs and surgery is the treatment of choice. This type of epilepsy may be due to Mesial Temporal Sclerosis (MTS), tumors [i.e. low grade glioma, Arterio-Venous Malformation (AVM) etc], trauma, infection (Tuberculosis) etc. Here we report five cases of surgically treated TLE that were due to a MTS, MTS with arachnoid cyst, low grade ganglioglioma, high grade ganglioglioma and a tuberculoma in the department of neurosurgery, Dhaka Medical College Hospital and Islami Bank Central Hospital, Dhaka, Bangladesh from August 2009 to February 2010. In all cases the only presenting symptoms was complex partial seizures (psychomotor epilepsy) for which all underwent scalp EEG (Electro Encephalogram) and MRI (Magnetic Resonance Imaging) of Brain. All patients were managed by amygdalohippocampectomy plus standard anterior lobectomy. One patient with high grade ganglioglioma recurred within two months of operation and expired within five months. The rest of the cases are seizure and disease free till the last follow up.