Transparahippocampal selective amygdalohippocampectomy in children and adolescents: efficacy of the procedure and cognitive morbidity in patients

Surgery for Intractable Epilepsy in Pediatrics, a Systematic Review of Outcomes other than Seizure Freedom

To perform a systematic review evaluating reported outcomes for epilepsy surgery in pediatric patients with pharmacoresistant epilepsy beyond seizure control, including impact on quality of life, behavioral, neurocognitive outcomes as well as complications, and death. We reviewed articles from both EMBASE and MEDLINE/PubMed articles that met formal criteria (patients ≤18 years, those with intractable epilepsy, at least 5 patients in the case series, published in peer-reviewed journal). Each reviewer independently reviewed the articles and those with discrepancies were discussed and consensus was reached. Out of a total of 536 abstracts obtained from EMBASE and MEDLINE/PubMed searches combined with additional cross-referencing, a total of 98 manuscripts ultimately met all inclusion criteria. The manuscripts were divided into 3 outcomes categories: Quality of Life (16), Cognitive Outcomes (60), and Deficits and Complications (50). Several papers fell into more than 1 category. These were separated by surgical types and evaluated. We found that overall reporting in all domains was variable and inconsistent amongst the different studies. This systematic review highlights the lack of completeness in reporting outcomes and complications involving pediatric epilepsy surgery and discordant results. This underscores the importance of multicenter systematic prospective data collection in pediatric patients who undergo pediatric epilepsy surgery.

Quantitative Meta-Analyses: Lateralization of Memory Functions Before and After Surgery in Children with Temporal Lobe Epilepsy

RATIONALE

Memory deficits in children with epilepsy have been reported in some but not all studies assessing the effects of side of seizures and resection from the temporal lobe on cognitive performance. This meta-analysis provides a quantitative systematic review of previous studies on this issue.

METHOD

A critical review and meta-analysis of the literature on memory performance in children with Temporal Lobe Epilepsy (TLE) was conducted. Search identified 25 studies, 13 of which compared children with TLE to healthy age-matched controls and 12 of which compared children with TLE before and after surgery.

RESULTS

Heterogeneity of the comparisons of children with TLE to healthy controls impeded drawing definitive conclusions. However, in 55% of the studies, verbal memory in children with left TLE (LTLE) was impaired as compared to healthy controls. Verbal memory performance slightly declines after pediatric LTLE surgery, but nonverbal memory tasks are not affected. By contrast, verbal memory performance is not affected by pediatric right TLE (RTLE) surgery.

CONCLUSIONS

The findings suggest that side of the epileptogenic zone and resection from the temporal lobe affect verbal memory in children with LTLE. Right resection seems to be safe with respect to verbal memory performance.

Memory dysfunctions

Since the seminal work on the patient HM, who in his adulthood presented an acquired amnesic syndrome following the resection of the bilateral temporal lobe, other research has described several cases of isolated memory dysfunction in children. This chapter presents developmental and long-lasting memory disorders emerging from an organic or neurologic cause at birth or in infancy. More notably, we focus on developmental amnesic syndrome caused by neonatal bihippocampal damage and memory dysfunction caused by medial temporal developmental epilepsy. We describe these two pediatric populations and present the consequences of hippocampal/medial temporal lobe damage in the development of memory systems. We review episodic memory deficits in children with developmental amnesia and temporal lobe epilepsy and highlight their impact on new learning, personal memories, and independent life. Finally, we provide a brief overview of some of the insights and debates emerging from classic work and recent advances in the context of episodic memory dysfunction displayed by children with hippocampal/medial temporal lobe amnesia and propose new perspectives in child neuropsychology of memory, suggesting new avenues for more ecologic memory assessment and rehabilitation.

Seizure outcome in pediatric medically refractory temporal lobe epilepsy surgery: selective amygdalohippocampectomy versus anterior temporal lobectomy

OBJECTIVE The aim of this study was to investigate long-term seizure outcome, rate of reoperation, and postoperative neuropsychological performance following selective amygdalohippocampectomy (SelAH) or anterior temporal lobectomy (ATL) in pediatric patients with medically refractory temporal lobe epilepsy (TLE). METHODS The authors performed a retrospective review of cases of medically refractory pediatric TLE treated initially with either SelAH or ATL. Standardized pre- and postoperative evaluation included seizure charting, surface and long-term video-electroencephalography, 1.5-T MRI, and neuropsychological testing. RESULTS A total of 79 patients treated initially with SelAH (n = 18) or ATL (n = 61) were included in this study, with a mean follow-up of 5.3 ± 4 years (range 1-16 years). The patients' average age at initial surgery was 10.6 ± 5 years, with an average surgical delay of 5.7 ± 4 years between seizure onset and surgery. Seizure freedom (Engel I) following the initial operation was significantly more likely following ATL (47/61, 77%) than SelAH (8/18, 44%; p = 0.017, Fisher's exact test). There was no statistically significant difference in the proportion of patients with postoperative neuropsychological deficits following SelAH (8/18, 44%) or ATL (21/61, 34%). However, reoperation was significantly more likely following SelAH (8/18, 44%) than after ATL (7/61, 11%; p = 0.004) and was more likely to result in Engel I outcome for ATL after failed SelAH (7/8, 88%) than for posterior extension after failed ATL (1/7, 14%; p = 0.01). Reoperation was well tolerated without significant neuropsychological deterioration. Ultimately, including 15 reoperations, 58 of 79 (73%) patients were free from disabling seizures at the most recent follow-up. CONCLUSIONS SelAH among pediatric patients with medically refractory unilateral TLE yields significantly worse rates of seizure control compared with ATL. Reoperation is significantly more likely following SelAH, is not associated with incremental neuropsychological deterioration, and frequently results in freedom from disabling seizures. These results are significant in that they argue against using SelAH for pediatric TLE surgery.

Neuropsychological outcomes following paediatric temporal lobe surgery for epilepsies: Evidence from a systematic review

OBJECTIVE

The systematic review aimed to assess the neuropsychological outcomes of temporal lobe resections for epilepsy in children. Additional objectives included determining whether earlier age at surgery leads to better neuropsychological outcomes; the relationships between and predictors of these outcomes.

METHODS

Using advanced search terms, a systematic review of electronic databases was conducted, comprising MEDLINE, Embase, PsycINFO, Global Health, Web of Science and CINAHL. Included studies reported on outcome following neurosurgical treatment for epilepsy. Specifically, studies were included if they reported neuropsychological outcomes and were concerned only with temporal lobe resection.

RESULTS

73 studies met inclusion criteria. For reported neuropsychological outcomes, the majority of participants remained stable after surgery; some declined and some improved. There was some evidence for increased material-specific memory deficits after temporal lobe surgery based on resection side, and more positive cognitive outcome for those with lower pre-surgical ability level.

SIGNIFICANCE

Retrieved evidence highlights the need for improvements to quality of methodology and reporting. Appropriately designed prospective multicentre trials should be conducted with adequate follow-up for long-term outcomes to be measured. Core outcome measures should be agreed between centres. This would permit higher quality evidence so that clinicians, young people and their families may make better informed decisions about whether or not to proceed with surgery and likely post-operative profile.

Neuropsychologist's (re-)view: Resective versus ablative amygdalohippocampectomies

Pharmacoresistant mesial temporal lobe epilepsy (mTLE) represents the major indication for epilepsy surgery. Since epilepsy surgery is an elective treatment option, preserving cognition is a high priority. Given the essential role of temporomesial structures in declarative long-term memory formation, surgical treatment for mTLE is primarily associated with a risk of material-specific memory decline, but other cognitive domains may be affected as well. The major determinants for the neuropsychological outcome are the functional integrity of surgically affected tissues, the functional reserve capacities of the remnant brain, the postoperative seizure outcome, as well as the quantitative and qualitative changes of antiepileptic drugs. Anterior temporal lobectomy has long been the standard procedure for treating mTLE. However, if an exclusive mesial pathology is present, then functional non-pathological tissues of the temporal pole and neocortex are sacrificed. As a result, more selective or tailored surgical approaches have been developed which strive towards minimizing iatrogenic effects. However, whether or not these approaches are equipotential with regard to seizure control is still a matter of debate. The quality of the presurgical diagnostics could also be decisive. Selective surgery should indeed be selective in terms of preventing evitable collateral cortical damage along the approach. Invasivity and risks of collateral damage associated with "open" selective resective surgery are further minimized by stereotactic ablative surgery via thermocoagulation, or eventually even eliminated by gamma knife surgery. From a neuropsychological point of view, this development is consequent and desirable, but no clear scientific evidence of a superior cognitive outcome after radiosurgery or thermocoagulation currently exists. The studies that are available contain significant methodological limitations. Thus, randomized head-to-head cognitive outcome studies of competing selective procedures are needed, which should meet the minimum requirements for study design and neuropsychological evaluations. Finally, none of the surgical treatment variants can systematically prevent memory decline when the hippocampus is targeted.

Transsylvian Selective Amygdalohippocampectomy for Mesiotemporal Epilepsy: Experience with 162 Procedures

BACKGROUND: Mesial temporal lobe epilepsy (MTLE) is one of the most common forms of epilepsy refractory to medical therapy. Among different surgical approaches, selective amygdalohippocampectomy has gained increasing interest for its rationale of isolated removal of the epileptogenic mesiotemporal area.

OBJECTIVE: To summarize our experience with surgical treatment of MTLE in 162 patients using the transsylvian approach and to analyze possible effects of length of hippocampal resection and postoperative gliosis on seizure and cognitive outcome.

METHODS: Clinical, radiological, histopathological and neuropsychological findings of 162 patients with MTLE who were operated by the senior author between 1993 and 2012 were retrospectively evaluated. Postoperative follow-up mounted up to 240 months (59 ± 56 months). Seizure outcome was available in 156 patients with minimum follow-up of 3 months. Extent of hippocampal resection was evaluated in 70 and postoperative gliosis in 62 of the 92 patients. Results were then correlated with seizure and cognitive outcome.

RESULTS: Of 134 patients with a follow-up of at least 1 year, 85 (63.4%) remained completely seizure free (Engel Ia) and 118 (88.0%) had a worthwhile improvement after surgery (Engel I+II). There was no perioperative death. Permanent morbidity was encountered in 4 patients (2.5%). Neither the extent of hippocampal resection nor postoperative gliosis correlated with seizure outcome or postoperative memory performance.

CONCLUSION: Transsylvian selective amygdalohippocampectomy can be recommended as an adequate procedure for the surgical treatment of mesiotemporal epilepsy with favorable epileptological results and acceptable morbidity.

Verbal memory after temporal lobe epilepsy surgery in children: Do only mesial structures matter?

OBJECTIVE

Previous findings have been mixed regarding verbal memory outcome after left temporal lobectomy in children, and there are few studies comparing verbal memory change after lateral versus mesial temporal lobe resections. We compared verbal memory outcome associated with sparing or including the mesial structures in children who underwent left or right temporal lobe resection. We also investigated predictors of postsurgical verbal memory change.

METHODS

We retrospectively assessed verbal memory change approximately 1 year after unilateral temporal lobe epilepsy surgery using a list learning task. Participants included 23 children who underwent temporal lobe surgery with sparing of the mesial structures (13 left), and 40 children who had a temporal lobectomy that included resection of mesial structures (22 left).

RESULTS

Children who underwent resection from the left lateral and mesial temporal lobe were the only group to show decline in verbal memory. Furthermore, when we considered language representation in the left temporal resection group, patients with left language representation and spared mesial structures showed essentially no change in verbal memory from preoperative to follow-up, whereas those with left language representation and excised mesial structures showed a decline. Postoperative seizure status had no effect on verbal memory change in children after left temporal lobe surgery. Finally, we found that patients with intact preoperative verbal memory experienced a significant decline compared to those with below average preoperative verbal memory.

SIGNIFICANCE

Our findings provide evidence of significant risk factors for verbal memory decline in children, specific to left mesial temporal lobe epilepsy. Children who undergo left temporal lobe surgery that includes mesial structures may be most vulnerable for verbal memory decline, especially when language representation is localized to the left hemisphere and when preoperative verbal memory is intact.

Surgical strategies for pediatric epilepsy

Pediatric epilepsy is a debilitating condition that impacts millions of patients throughout the world. Approximately 20-30% of children with recurrent seizures have drug-resistant epilepsy (DRE). For these patients, surgery offers the possibility of not just seizure freedom but significantly improved neurocognitive and behavioral outcomes. The spectrum of surgical options is vast, ranging from outpatient procedures such as vagus nerve stimulation to radical interventions including hemispherectomy. The thread connecting all of these interventions is a common goal-seizure freedom, an outcome that can be achieved safely and durably in a large proportion of patients. In this review, we discuss many of the most commonly performed surgical interventions and describe the indications, complications, and outcomes specific to each.

Neurocognitive function in children after anterior temporal lobectomy with amygdalohippocampectomy

BACKGROUND

We assessed the postoperative neurocognitive function after temporal lobectomy in children with temporal lobe epilepsy.

METHODS

This was a retrospective analysis of the data of 20 patients with Engel's class I or II outcomes after anterior temporal lobectomy with amygdalohippocampectomy between 2005 and 2008. Twenty children underwent resection of either dominant (n = 8) or nondominant (n = 12) temporal lobes, and their median age at surgery was 12.8 ± 3.2 years. We serially assessed intelligence and memory function as measured by the Korean-Wechsler Scales of Intelligence and Rey-Kim Memory test both before and after surgery.

RESULTS

Intelligence quotient (IQ) and memory quotient scores remained stable during a 3.6-year median follow-up in these children after the surgery. There was no decrease of IQ or memory quotient scores in either the dominant or non-dominant hemisphere groups. Later onset of epilepsy, a shorter epilepsy duration, a smaller number of antiepileptic drugs, and postoperative seizure-free outcomes were significant good predictors of the postoperative IQ.

CONCLUSION

Temporal lobectomy in children did not provoke a significant decline in intelligence or memory function. Early surgical treatment in children with intractable seizures of temporal lobe origin may result in better neurocognitive outcomes.

Surgical treatment of epilepsy

PURPOSE OF REVIEW

This article outlines indications for neurosurgical treatment of epilepsy, describes the presurgical workup, summarizes surgical approaches, and details expected risks and benefits.

RECENT FINDINGS

There is class I evidence for the efficacy of temporal lobectomy in treating intractable seizures, and accumulating documentation that successful surgical treatment reverses much of the disability, morbidity, and excess mortality of chronic epilepsy.

SUMMARY

Chronic, uncontrolled focal epilepsy causes progressive disability and increased mortality, but these can be reversed with seizure control. Vigorous efforts to stop seizures are warranted. If two well-chosen and tolerated medication trials do not achieve seizure control, an early workup for epilepsy surgery should be arranged. If this workup definitively identifies the brain region from which the seizures arise, and this region can be removed with a low risk of disabling neurologic deficits, neurosurgery will have a much better chance of stopping seizures than further medication trials.

Everyday memory in children after resective epilepsy surgery

This study investigated parent reports of everyday memory and performance on objective memory tests in children with intractable epilepsy. Participants were 119 children with epilepsy (75 of whom underwent surgery) and 57 healthy controls. The group with epilepsy was examined twice, approximately 2 years apart. Parents reported on their child's memory as manifested in everyday activities and situations, and children with epilepsy completed standardized objective memory tests. At baseline, the children with epilepsy had poorer everyday memory than the healthy control group. Memory did not change significantly over time in the children with epilepsy, and no changes were found related to surgery or to seizure outcome. Intractable epilepsy in childhood is associated with difficulty in using memory in everyday activities. Resective surgery does not result in changes in the parents' observations of their child's memory as manifested in their daily functioning or in the child's performance on objective measures of memory.

Temporal lobe epilepsy surgery in children versus adults: from etiologies to outcomes

Temporal lobe epilepsy (TLE) is the most common type of medically intractable epilepsy in adults and children, and mesial temporal sclerosis is the most common underlying cause of TLE. Unlike in the case of adults, TLE in infants and young children often has etiologies other than mesial temporal sclerosis, such as tumors, cortical dysplasia, trauma, and vascular malformations. Differences in seizure semiology have also been reported. Motor manifestations are prominent in infants and young children, but they become less obvious with increasing age. Further, automatisms tend to become increasingly complex with age. However, in childhood and especially in adolescence, the clinical manifestations are similar to those of the adult population. Selective amygdalohippocampectomy can lead to excellent postoperative seizure outcome in adults, but favorable results have been seen in children as well. Anterior temporal lobectomy may prove to be a more successful surgery than amygdalohippocampectomy in children with intractable TLE. The presence of a focal brain lesion on magnetic resonance imaging is one of the most reliable independent predictors of a good postoperative seizure outcome. Seizure-free status is the most important predictor of improved psychosocial outcome with advanced quality of life and a lower proportion of disability among adults and children. Since the brain is more plastic during infancy and early childhood, recovery is promoted. In contrast, long epilepsy duration is an important risk factor for surgically refractory seizures. Therefore, patients with medically intractable TLE should undergo surgery as early as possible.

Cognitive outcome of surgery

Epilepsy surgery is now widely accepted as an effective therapeutic option for carefully selected children with medically refractory epilepsy. The surgical procedure may cause cognitive deficits or exacerbate existing impairments, but it may also improve cognitive abilities by the restoration of functions located in adjacent or contralateral areas that had been secondarily affected by the epilepsy or the underlying pathology. Compared to adults, better cognitive outcome has been reported in children, a finding probably due to the developing state of the brain, which possesses considerable structural and functional plasticity. More extensive and effective surgery such as hemispherectomy is more commonly used in the pediatric population, and this must also influence surgical outcome. However, studies related to cognitive outcome of epilepsy surgery in children are limited, and controversial results are often reported. In this chapter, we provide a current overview of the literature on cognitive outcomes in children who undergo different types of epilepsy surgery, including focal resections as well as corpus callosotomy and hemispherectomy. Early surgical intervention appears to be a rational option for the treatment of childhood epilepsy since many cognitive deficits are linked to the epileptic process and may disappear when seizures are controlled.

Cognitive development from two to ten years after pediatric epilepsy surgery

The development of cognitive functions and the sustainability of seizure control between two and ten years after epilepsy surgery were prospectively investigated in 17 children and adolescents. Intelligence quotient remained stable. Learning capacity improved. Verbal memory improved in half of the subjects and declined in half, whereas figurative memory declined in most patients. Working memory improved as did attention regarding sustained attention and impulse control. In contrast, reaction times were longer, and the auditory attention span was shorter. Executive functions were not affected. Six subjects (35%) were seizure free at the 10-year follow-up, and a seizure reduction of more than 75% had been achieved in 13 (76%). Seizure control improved in five and seizures recurred in two subjects between the two- and the 10-year follow-up.

Surgical techniques for the treatment of temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is the most common form of medically intractable epilepsy. Advances in electrophysiology and neuroimaging have led to a more precise localization of the epileptogenic zone within the temporal lobe. Resective surgery is the most effective treatment for TLE. Despite the variability in surgical techniques and in the extent of resection, the overall outcomes of different TLE surgeries are similar. Here, we review different surgical interventions for the management of TLE.

Cranial nerve monitoring during subpial dissection in temporomesial surgery

OBJECTIVE

Cranial nerves (CNs) crossing between the brainstem and skull base at the level of the tentorial hiatus may be at risk in temporomesial surgery involving subpial dissection and/or tumorous growth leading to distorted anatomy. We aimed to identify the surgical steps most likely to result in CN damage in this type of surgery.

METHODS

Electromyographic responses obtained with standard neuromonitoring techniques and a continuous free-running EMG were graded as either contact activity or pathological spontaneous activity (PSA) during subpial resection of temporomesial structures in 16 selective amygdalohippocampectomy cases. Integrity of peripheral motor axons was tested by transpial/transarachnoidal electrical stimulation while recording compound muscle action potentials from distal muscle(s).

RESULTS

Continuous EMG showed pathological activity in five (31.2%) patients. Nine events with PSA (slight activity, n = 8; strong temporary activity, n = 1) were recorded. The oculomotor nerve was involved three times, the trochlear nerve twice, the facial nerve once, and all monitored nerves on three occasions. Surgical maneuvers associated with PSA were the resection of deep parts of the hippocampus and parahippocampal gyrus (CN IV, twice; CN III, once), lining with or removing cotton patties from the resection cavity (III, twice; all channels, once) and indirect exertion of tension on the intact pia/arachnoid of the uncal region while mobilizing the hippocampus and parahippocampal gyrus en bloc (all channels, once; III, once). CMAPs were observed at 0.3 mA in two patients and at 0.6 mA in one patient, and without registering the exact amount of intensity in three patients.

CONCLUSION

The most dangerous steps leading to cranial nerve damage during mesial temporal lobe surgery are the final stages of the intervention while the resection is being completed in the deep posterior part and the resection cavity is being lined with patties. Distant traction may act on nerves crossing the tentorial hiatus via the intact arachnoid.

Intraoperative Anatomic Landmarks for Resection of the Amygdala during Medial Temporal Lobe Surgery

OBJECTIVE

To establish reliable gross landmarks for resecting the amygdala intraoperatively, especially during anteromedial temporal lobectomy and amygdalohippocampectomy for epilepsy surgery. Reliable landmarks would allow its safe and complete resection as well as its potential en bloc removal for detailed electrophysiological and histopathological analyses.

METHODS

Ten adult cadavers (20 sides) were used. Two adjacent anatomic structures were identified: the bifurcation of the middle cerebral artery (MCA point) and the entry point of the anterior choroidal artery (AChoA) at the anterior origin of the choroid plexus into the temporal horn (inferior choroidal point referred to as the AChoA point). Following removal of the brain tissue inferior and anterior to the imaginary line connecting these 2 anatomic landmarks, cross sectional histopathological analysis of the remaining temporal and frontal lobes was performed to verify the presence or absence of any nervous tissue belonging to the amygdala complex.

RESULTS

In all 20 sides, the entire amygdala complex was found anterior and inferior to the transection made along the MCA-AChoA line. No apparent injury to the adjacent striatum was discovered.

CONCLUSION

Two easily identifiable points, including the middle cerebral artery bifurcation and the inferior choroidal point, may define a line that reliably disconnects the amygdala complex from the remaining temporal and frontal lobes. These landmarks may assist in resection of the amygdale while preserving important adjacent structures, including the striatum.

Modifications to the subtemporal selective amygdalohippocampectomy using a minimal-access technique: seizure and neuropsychological outcomes

Object

The authors introduce a minimal-access subtemporal approach for selective resection of the amygdala and hippocampus in patients with temporal lobe epilepsy and describe seizure and neuropsychological outcomes.

Methods

Between October 2003 and April 2007, 41 consecutive patients with intractable unilateral nonlesional temporal lobe epilepsy underwent image-guided subtemporal amygdalohippocampectomy. Baseline characteristics, preoperative evaluations, and seizure outcomes were assessed. Eighteen patients underwent pre- and postoperative neuropsychological testing for cognitive functioning, executive functioning, verbal and visual memory, and mood.

Results

Important aspects of the subtemporal approach include a low temporal keyhole craniotomy, use of image guidance, preservation of the tentorium, incision in the fusiform gyrus, and subpial, en bloc resection of the hippocampus. There were no deaths and no cases of significant postoperative morbidity. At 1 year, 29 of 36 patients (81%) were without seizures or auras. At 2 years, 17 of 23 (74%) patients were seizure- and aura-free. Detailed neuropsychological testing of language, memory, cognitive functioning, and executive functioning suggested that most patients exhibited either stability or improvement in their scores, regardless of language lateralization.

Conclusions

A minimal-access subtemporal approach for amygdalohippocampectomy is an effective treatment for temporal lobe epilepsy yielding encouraging preliminary seizure and neuropsychological outcomes.

Limited access inferior temporal gyrus approach to mesial basal temporal lobe tumors

Object

In this retrospective review, the authors examine the clinical characteristics, diagnosis, and outcome of surgery in 25 consecutive patients with mesial basal temporal lobe (MBTL) tumors. A limited access approach to the inferior temporal gyrus (ITG) was used.

Methods

Patients with MBTL tumors were identified from the epilepsy and tumor surgery database at the authors' institution. Intraaxial tumors localized to the mesial basal structures, and without involvement of the cortical surface of the temporal lobe, temporal stem, and basal ganglia were included. Preoperative and postoperative MR images were obtained in all patients. The mean follow-up period was 24 months (range 9–36 months). Preoperative symptoms, neurological deficits, outcomes, surgical complications, and a technical description of the approach are discussed.

Results

Intraaxial MBTL tumors in 25 patients (mean age 44 years, range 8–76 years) were resected using a limited access approach via the ITG. The largest groups of tumors were high-grade gliomas and dysembryoblastic neuroepithelial tumors (8 in each group), followed by oligodendrogliomas, cerebral metastases, and gangliogliomas. Seizures, headaches, and disorientation were the most common preoperative symptoms. Postoperative MR images demonstrated gross-total resection in all cases. There were 2 surgical complications (a superficial wound infection and a transient frontalis branch palsy). There were no permanent neurological complications or significant new hemianoptic defects.

Conclusions

A limited access ITG approach performed with intraoperative image guidance offers an alternative corridor for resection of MBTL tumors (Schramm Type A). This approach may be technically less demanding than the transsylvian or subtemporal approach. Gross-total resection is feasible utilizing this approach and compares favorably with other, more classical approaches.

Neuropsychological deficits in childhood epilepsy syndromes

Seizure disorders are relatively common in childhood, and the International League Against Epilepsy (ILAE) provides a hierarchical classification system to define seizure types. At the final level of classification, specific epilepsy syndromes are defined that represent a complex of signs and symptoms unique to an epilepsy condition. The present review discusses the issues related to several of these epilepsy syndromes in childhood, including those classified as generalized idiopathic epilepsies (e.g., childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy), focal epilepsies (benign rolandic epilepsy, occipital epilepsy, temporal lobe epilepsy, frontal lobe epilepsy) and the "epileptic encephalopathies," including Dravet's Syndrome, West Syndrome, Lennox-Gastaut Syndrome, Myoclonic Astatic Epilepsy, and Landau-Kleffner Syndrome. For each syndrome, the epidemiology, clinical manifestations, treatments, and neuropsychological findings are discussed.

Neuropsychological deficits in childhood epilepsy syndromes

Seizure disorders are relatively common in childhood, and the International League Against Epilepsy (ILAE) provides a hierarchical classification system to define seizure types. At the final level of classification, specific epilepsy syndromes are defined that represent a complex of signs and symptoms unique to an epilepsy condition. The present review discusses the issues related to several of these epilepsy syndromes in childhood, including those classified as generalized idiopathic epilepsies (e.g., childhood absence epilepsy, juvenile absence epilepsy, juvenile myoclonic epilepsy), focal epilepsies (benign rolandic epilepsy, occipital epilepsy, temporal lobe epilepsy, frontal lobe epilepsy) and the "epileptic encephalopathies," including Dravet's Syndrome, West Syndrome, Lennox-Gastaut Syndrome, Myoclonic Astatic Epilepsy, and Landau-Kleffner Syndrome. For each syndrome, the epidemiology, clinical manifestations, treatments, and neuropsychological findings are discussed.

Memory functions following surgery for temporal lobe epilepsy in children

Surgical treatment appears to improve the cognitive prognosis in children undergoing surgery for temporal lobe epilepsy (TLE). The beneficial effects of surgery on memory functions, particularly on material-specific memory, are more difficult to assess because of potentially interacting factors such as age range, intellectual level, left-handedness, type of surgery and seizure outcome. This study investigated memory functions in 20 right-handed children who had left or right-temporal lobe surgery - including hippocampectomy - and became seizure-free. The neuropsychological evaluation included tests measuring verbally and visually mediated episodic memory, everyday memory as well as attention/working memory and language/semantic memory. We also assessed the relationships between age of seizure onset, general cognitive ability and memory functions. Children with TLE showed poor memory efficiency before surgery that tended to improve about 1 year after surgery. We found a material-specific memory effect, especially after surgery-9 (out of 12) children with left TLE had worse verbal memory results while 5 (out of 8) with right TLE had worse visual memory results. Post-operatively, most children had poor everyday memory performance on the Rivermead Behavioural Memory Test. No significant relationship was observed between episodic memory scores and age of epilepsy onset but children with early onset remained with lower Performance IQ values, Rey's figure copy scores and naming performances after surgery. Surgery significantly improved all the attention/working memory scores, some verbal episodic memory tasks and naming test performances. A different pattern of episodic and semantic memory limitations related to left or right TLE was observed.

Surgery for temporal mediobasal tumors: experience based on a series of 235 patients

OBJECTIVE

To describe the clinical characteristics, diagnosis, various approaches, and outcomes in a retrospective review of a large series of temporomediobasal (TMB) tumors.

METHODS

Charts from 235 patients with TMB tumors were identified from the glioma and epilepsy surgery database and from the electronic operations log. Preoperative magnetic resonance imaging scans were available for all patients and postoperative follow-up was available for 155 of these patients (mean follow-up period, 59 mo; range, 2-172 mo). Preoperative symptoms, approaches, technical problems, and surgical complications are described.

RESULTS

Two hundred and thirty-five patients with intra-axial TMB tumors (mean age, 35 yr) were collected during an 11-year period. The largest tumor groups were astrocytomas (38.0%), gangliogliomas (29.8%), dysembryoplastic neuroepithelial tumor (11.1%), and glioblastomas (11.1%). The most frequent tumor location was the mesial Type A tumor (45.1%), with this type also showing the highest proportion of benign (World Health Organization Grades I and II) histological features (91.3%). Of all tumors, 76.2% were benign. Larger tumor size was associated with higher frequency of malignant histopathological findings. The leading symptom was epilepsy in 91% of patients, followed by drug-resistant epilepsy in 71.5%. Significant preoperative neurological deficits, such as hemiparesis or aphasia, were seen in 3.8% of the patients; another 12% had visual field deficits. Thirty-eight patients with low-grade tumors had undergone surgery previously. Several surgical approaches were chosen: transsylvian in 28%, anterior two-thirds temporal lobe resection in 23%, temporal pole resection in 15.3%, subtemporal in 19%, and transcortical in 6%. The most frequent neurological complications were transient: dysphasia (4.2%), hemiparesis (5%), and oculomotor disturbance (2.5%). Permanent nonvisual neurological complications occurred in fewer than 2% of the patients and significant new hemianopic defects were found in another 5.4% of the patients. The most severe complication was one intraoperative internal carotid artery lesion. One patient died.

CONCLUSION

Small tumor size, magnetic resonance imaging, and microsurgery have made resection of mostly benign TMB tumors possible in a large number of patients. This series supports the conclusion that these tumors can be operated on with a relative degree of safety for the patient, provided that the anatomy of the mesial temporal lobe and the variety of approaches are well known to the surgeon. However, because of the complex anatomic structures in the vicinity, transient neurological deterioration is not infrequent and certain neurological disturbances (e.g., quadrantanopia) even seem to be unavoidable, whereas permanent significant deficits are rare.

Memory Outcome After Pediatric Epilepsy Surgery: Objective and Subjective Perspectives

Memory was investigated in 27 children and adolescents in a longitudinal study before and at one and two years after epilepsy surgery. A comparison group with intractable epilepsy (n = 15), matched in age, sex, age of seizure onset, and IQ, was studied at comparable points in time. Methods included administration of standardized measures of story recall and face recognition, and qualitative interviews to probe the participants' perceptions of their memory function over time. There was no significant change over time in either group on the standardized measures. Site and laterality of excision, age at surgery, and seizure outcome were not predictive of change within the surgical group. The narratives revealed facets of memory that were problematic in daily life. The objective and subjective results showed low concordance regarding change, possibly due to limitations in the objective measures for capturing semantic and autobiographical memory.

Memory, emotional and vocational impairments before and after anterior temporal lobectomy for complex partial seizures

PURPOSE

To assess the pre- and postsurgical frequency of memory, emotional, and vocational impairments in patients who underwent anterior temporal lobectomy (ATL), and to assess the relationship between emotional disturbance and memory abilities after ATL.

METHODS

Retrospective analysis of data was performed on 90 patients with medically intractable complex partial seizures who underwent ATL between 1981 and 2003. Patients were evaluated an average of 5 months before surgery and 11.3 months after surgery.

RESULTS

A moderate to high frequency of memory impairment (44.4%; verbal or nonverbal), emotional disturbance (38.9%) and unemployment (27.8%) existed in the same individuals both before and after surgery. There were small to moderate rates of new onset memory (18.9%), emotional (11.1%), and vocational (7.8%) difficulties after surgery often regardless of seizure control outcome. Patients who underwent left-ATL and had emotional disturbance after surgery had the lowest verbal memory test scores.

CONCLUSIONS

Results highlight the importance of taking into account emotional status when assessing memory abilities after ATL. Results replicate the finding of moderate to high frequencies of memory impairment, emotional disturbance, and unemployment both before and after ATL. Results provide support for the rationale that cognitive, psychiatric and vocational interventions are indicated to mitigate the problems that exist before and persist after ATL.

Temporal lobe resections

INTRODUCTION

In the 50 years since Penfield outlined the requirements of the epilepsy surgeon, we have seen the introduction of the digitised electroencephalogram (EEG), video telemetry and the magnetic resonance imaging (MRI) scan. In the operating room, advances in neuro-anaesthesia, the introduction of the operating microscope, image guidance and the ultrasonic aspirator have greatly enhanced the surgeons' technical ability. Despite these changes, the thesis encapsulated in Penfield's statement is that the surgeon needs to understand and interpret the preoperative data in such a way as to identify as closely as possible the epileptogenic zone where he must carry out surgery with the utmost care and diligence, and finally, in the context of audit and follow-up of his surgical patients, he must be able to predict for each individual case the likelihood of success and failure of any particular procedure.

CONCLUSION

Previous articles in this supplement have looked at the specific investigations carried out to identify the epileptogenic zone, but once this data has been gathered, it is the responsibility of the neurosurgeon, within the context of the multidisciplinary team, to decide whether surgery is both feasible and advisable and then to discuss this in depth with the patient and their family and carers. The multidisciplinary epilepsy surgery meeting allows cases to be discussed in an open forum and the decisions made in this meeting can then be discussed with the family. The process of consent will begin from the moment any surgical procedure is discussed and should, wherever possible, be reinforced with written, as well as verbal, information. The process of consent should be a continuum until the actual day of surgery. All parties involved in the care and management of the patient should be regarded as stakeholders in this decision, and it is vital that all these stakeholders are working towards a common goal.

OBJECTIVES

In this article, I will consider the specific aspects of the presurgical investigations that are applicable to the temporal lobe and the differing types of surgery that are likely to be indicated. I will then describe, in detail, the surgical technique of temporal lobe resection, highlighting some of the pitfalls and successes that such surgery can provide.

Cognitive assessment in epilepsy surgery of children

INTRODUCTION

Although the neurocognitive assessment in children as in the adults is an important step before and after surgery, in the literature, the data about pre- and postoperative neurocognitive evaluations in children are very few.

OBJECTIVE

The purpose of this paper is to consider some peculiar aspects of the neurocognitive assessment during development, and report literature data about neuropsychological outcome of epileptic children treated with focal resection and hemispherectomy.

RESULTS AND DISCUSSION

The second section concerns our personal experience about a cohort of 45 children with refractory epilepsy operated on before 7 years. The results suggest that early surgical treatment is generally effective for seizure control and behavior improvement in children with refractory epilepsy. Concerning cognitive outcome, we found that the neurocognitive level was unchanged in the majority of the patients.

CONCLUSION

We underline the importance of multicentric studies with standardized neuropsychological assessments in large series of young children.

Specific memory impairment in a multiple disabled male with fragile X syndrome and temporal lobe epilepsy

Evaluation of the cognitive repercussions of an epileptic disorder and its treatment are important issues in clinical follow-up. This especially holds true for temporal lobe epilepsy (TLE) where resective surgery can be a valid treatment option. However, in patients where TLE coexists with another neurocognitive disorder, questions can arise about the precise nature of the neuropsychological deficits. The aim of the present study was to evaluate memory impairments, found in a male aged 12 years who had the dual pathology of fragile X syndrome and refractory TLE. Memory functions of this child were compared with those of a male aged 11 years 7 months with fragile X syndrome matched for intellectual functioning as indicated by highly comparable verbal (5 y 5 mo vs 5 y 9 mo) and non-verbal (7 y 2 mo vs 6 y 1 mo) cognitive age equivalents. Performance on each neuropsychological measure was evaluated twice, separately with normative data based on chronological age and on verbal or non-verbal cognitive level. A specific, distinguishable profile of task performance could be found only when controlling for general level of cognitive functioning. This made it possible to accurately evaluate neuropsychological abilities before and 6 months after anterior temporal lobe resection even in this male with a complex neurological pathology.

Greater functional recovery after temporal lobe epilepsy surgery in children

The purpose of our study is to evaluate whether children recover better than adults from memory deficits as a consequence of temporal lobe surgery. We compared 3 and 12 month outcomes obtained in children and adults with medically refractory epilepsy. Each candidate underwent temporal lobe resection for seizure control and children were matched with regard to pathology, onset of epilepsy, side of surgery and type of surgery with adults (N = 30 for each group, mean age at surgery 13 versus 30 years). Three months after surgery, both left-resected groups displayed a significant decline in verbal learning capacity. During the following 9 months, only the children recovered and were able to reach their preoperative level 1 year after surgery. The left-resected adults remained, for the most part, on their low level and one year after surgery, they were still significantly worse than at the time of their preoperative examination. The right-resected adults experienced a deterioration in visual memory 1 year after surgery relative to the results of the short-term follow-up; the children improved. The children also had a better outcome with regard to attentional functions and, as a trend, a better seizure outcome (Engel Outcome I--1 year after surgery: 63% adults, 80% paediatric patients). Our neuropsychological data provide evidence of greater plasticity and compensational capacity in childhood. The results can be taken as a strong argument for early surgical intervention.

Temporal lobe magnetic resonance spectroscopic imaging following selective amygdalohippocampectomy for treatment-resistant epilepsy

OBJECTIVES

Magnetic resonance spectroscopic imaging (MRSI) may show circumscribed or extensive decreased brain N-acetyl aspartate (NAA)/creatine and phosphocreatine (Cr) in epilepsy patients. We compared temporal lobe MRSI in patients seizure-free (SzF) or with persistent seizures (PSz) following selective amygdalohippocampectomy (SAH) for medically intractable mesial temporal lobe epilepsy (mTLE). We hypothesized that PSz patients had more extensive temporal lobe metabolite abnormalities than SzF patients.

MATERIALS AND METHODS

MRSI was used to study six regions of interest (ROI) in the bilateral medial and lateral temporal lobes in 14 mTLE patients following SAH and 11 controls.

RESULTS

PSz patients had more temporal lobe ROI with abnormally low NAA/Cr than SzF patients, including the unoperated hippocampus and ipsilateral lateral temporal lobe.

CONCLUSION

Postoperative temporal lobe MRSI abnormalities are more extensive if surgical outcome following SAH is poor. MRSI may be a useful tool to improve selection of appropriate candidates for SAH by identifying patients requiring more intensive investigation prior to epilepsy surgery. Future prospective studies are needed to evaluate the utility of MRSI, a predictor of successful outcome following SAH.

Memory and intelligence outcome following surgery for intractable temporal lobe epilepsy: relationship to seizure outcome and evaluation using a customized neuropsychological battery

The main objectives of this prospective study were to (1) assess memory and intelligence outcome following surgery for intractable temporal lobe epilepsy, (2) correlate this with seizure outcome and side of surgery, and (3) perform (1) and (2) using an indigenously developed battery customized to the Indian population. Prior to use in our epilepsy surgery program, the test-retest and interexaminer variance reliability of this battery had been established in both normal and cognitively compromised populations. The memory scores were overall rather than material-specific. The battery was administered to right-handed adults undergoing surgery for intractable temporal lobe epilepsy without any evidence of opposite temporal lobe abnormality, both presurgery and postsurgery at a mean follow-up of 8 months. Twenty-five consecutive patients were included; 13 underwent right and 12 underwent left temporal surgery. Seizure outcome was assessed using Engel's classification. Among 13 patients who underwent right temporal surgery, although 4 patients with poor seizure outcome had insignificant changes in scores, 7 of 9 patients with good seizure outcome exhibited considerable (> 20% over preoperative) improvement in their memory and intelligence scores. Statistical analysis using Student's t test and the Mann-Whitney test revealed that the patients who underwent right temporal surgery with good seizure outcome had significant improvement in both memory (P = 0.007) and intelligence (P = 0.043) scores compared with those with poor seizure outcome. In contrast, patients who underwent left temporal surgery had no significant change in cognitive scores irrespective of seizure outcome. Cognitive improvement seems to occur in patients with good seizure outcome following nondominant temporal lobe surgery for intractable epilepsy with no evidence of pathology in the opposite temporal lobe. The same finding was not observed in patients undergoing left temporal surgery.

Neuropsychological outcome following focal cortical removal for intractable epilepsy in children

In children, surgery for epilepsy has been recognized as a viable treatment option since publication of S. Davidson and M.A. Falconer's outcome study in 1975 [Lancet North Am Ed 5:1260-3], which demonstrated that medical outcome of children who underwent anterior temporal lobectomy paralleled that of adults. Pediatric surgical programs and the literature on medical outcome have grown considerably since that time, with surgery being offered to children with temporal but also extratemporal epilepsy foci. Comparatively little work has been conducted in the area of neuropsychological outcome. This article outlines differences in adult and pediatric outcome studies, reviews the literature on the intellectual and memory outcome in children, and discusses shortcomings of the pediatric outcome research conducted to date.

Analysis of different types of resection for pediatric patients with temporal lobe epilepsy

OBJECTIVE

Resection strategies for the treatment of temporal lobe epilepsy (TLE) are a matter of discussion. Few data on the significance of resection type are available for pediatric patients with TLE.

METHODS

Data for a series of 89 children who were surgically treated for TLE were analyzed. A first cohort of patients were mainly surgically treated with anterior temporal lobectomies. For a second cohort, resections were preoperatively "tailored" to the lesion and presumed epileptogenic area.

RESULTS

The follow-up period was 46 months (range, 14-118 mo). Seventy-seven patients (87%) attained satisfactory seizure control (82% Engel Class I and 5% Class II). For 12 patients (13%), seizure control was unsatisfactory (8% Class III and 5% Class IV). Anterior temporal lobectomies resulted in 94% satisfactory seizure control (33 patients), whereas the success rates were only 74% (20 patients) for amygdalohippocampectomy (AH) (P = 0.023) and 77% (13 patients) for lesionectomy plus hippocampectomy (not significant). All patients who underwent purely lateral temporal lesionectomies became seizure-free (14 patients). Logistic regression revealed the factors of AH (P = 0.021) and left-side surgery (P = 0.017) as significant predictors of unsatisfactory seizure control. Satisfactory seizure control was not dependent on the histopathological diagnoses. There was a low rate of verbal memory deterioration after left-side operations. Neuropsychological deterioration was rare after right temporal resections. Attentional and contralateral functions improved after surgery.

CONCLUSION

Surgery for the treatment of juvenile TLE is successful and safe, but the resection type may influence outcomes. Results after AHs were disappointing, probably because of difficulties in precise localization of the epileptogenic focus among children. Neuropsychological results demonstrated minimal rates of deterioration and significant improvements in contralateral functions. Surgical treatment of juvenile TLE should be encouraged, but the use of especially left AH should possibly be restricted.

Cognitive, Psychosocial, and Family Function One Year after Pediatric Epilepsy Surgery

PURPOSE

Assumptions regarding the benefits of seizure control after pediatric epilepsy surgery for cognitive, psychosocial, and family function were explored in a prospective study of 51 children with intractable epilepsy.

METHODS

Thirty children who underwent surgery were studied before and 1 year after surgery, and a comparison group of 21 children with medically refractory seizures was examined at comparable times.

RESULTS

One year after surgery, 57% of the surgical group was seizure free. Seizure status after surgery did not predict change over time in any of the areas measured. Cognitive and psychosocial status did not change over time in either group, and the strongest predictor of individual change in psychosocial status in the surgical group was baseline level of function. Within the surgical group, a trend toward an increase in independence promotion was noted in the family, but the children's satisfaction with the family declined.

CONCLUSIONS

These findings challenge the assumption that elimination of seizures will result in improved cognitive, psychosocial, and family functioning, at least within the first year after surgery.

Long-term seizure outcomes following amygdalohippocampectomy

OBJECT

Analyses of the results of surgery for epilepsy are hindered by inconsistent classifications of seizure outcome, small numbers of patients, and short postoperative follow-up periods. The authors conducted a retrospective study with a reassessment of the long-term seizure outcomes in patients who underwent selective amygdalohippocampectomy (SelAH) for pharmacotherapy-resistant mesial temporal lobe epilepsy (MTLE) at the Zurich University Hospital from 1975 to 1999.

METHODS

Year-by-year data and the last available data on seizure outcomes were retrospectively assessed for 369 consecutively surgically treated patients who had participated in a follow-up period longer than 1 year as of 1999 and whose outcomes were classified according to the Engel scale and the proposed new International League Against Epilepsy (ILAE) scale. Patients were grouped into nonlesional and lesional MTLE groups depending on whether they harbored a gross anatomical lesion that caused the MTLE. Differentiation was made between curative and palliative operations. Complications related to surgery are reported for 453 patients who underwent SelAH and participated in more than 3 months of follow-up review. The last available outcome data according to the Engel scale were found to be generally similar to those of the new ILAE classification, with 66.9% of patients free from disabling seizures (Engel Class I) compared with 57.1% who were completely seizure and aura free (ILAE Class 1). The last available data on seizure outcome were not significantly different between patients in the lesional and nonlesional MTLE groups. In the lesional group, seizure outcomes were significantly better when patients underwent surgery early in the course of the disease. Overall, 70% of the patients received reductions in their antiepileptic drug treatment at the time of the last available follow-up review. Complications related to the surgical procedures were rare.

CONCLUSIONS

The authors conclude that SelAH is a safe and effective surgical procedure for MTLE.

Pre- and postoperative verbal memory in pediatric patients with temporal lobe epilepsy

Outcome studies concerning memory after pediatric temporal lobe surgery in the treatment of epilepsy are rare and have not yielded consistent results. In the present study, 55 children and adolescents with temporal lobe epilepsy (TLE; 26 left, 29 right, 6-17 years) performed a verbal memory test before and 3 as well as 12 months after different types of temporal lobe resections (anterior lobectomy, amygdalo-hippocampectomy (AH), lesionectomy (LX)). Groups did not significantly differ before surgery. Three months after surgery, the left resected group showed a decline in learning and delayed recall, and performed significantly lower than the right resected group. Recoveries were evident 1 year after surgery. The postoperative memory declines were associated with a left-sided resection and a higher preoperative performance. Comparisons on the different resection types suggest a special risk in patients undergoing a left-sided AH. In summary, our results indicate a functional association of verbal memory functions with the left temporal lobe similar to findings in adult patients. Declines after left-sided temporal resections seem to be reversible at least for part of the children, perhaps due to the greater plasticity of the immature brain.

Memory and epilepsy: characteristics, course, and influence of drugs and surgery

Memory processing in humans is essential for consciousness, cognitive-behavioral development and individual biography. In epilepsy, declarative memory functions show characteristic patterns of impairment when mesiotemporal and associated neocortical structures are affected by lesions, ongoing epileptic activity, or the undesired effects of conservative or operative treatment. Major issues are thus the etiology, onset and course of memory impairment, as well as the prevention of further memory decline during treatment. New input in the field has resulted from improved imaging techniques, sophisticated experimental study designs, more selective surgical approaches, and new antiepileptic drugs.