Fornicotomy for the Treatment of Epilepsy: An Examination of Historical Literature in the Setting of Modern Operative Techniques.

Fornicotomy has been used to treat intractable temporal lobe epilepsy with mixed success historically; however, modern advances in stereotactic, neurosurgical, and imaging techniques offer new opportunities to target the fornix with greater precision and safety. In this review, we discuss the historical uses and quantify the outcomes of fornicotomy for the treatment of temporal lobe epilepsy, highlight the potential mechanisms of benefit, and address what is known about the side effects of the procedure. We find that fornicotomy, with or without anterior commissurotomy, resulted in 61% (83/136) of patients having some seizure control benefit. We discuss the potential operative approaches for targeting the fornix, including laser ablation and the use of focused ultrasound ablation. More work is needed to address the true efficacy of fornicotomy in the modern surgical setting. This review is intended to serve as a framework for developing this approach.

Elimination of medically intractable epileptic drop attacks following endoscopic total corpus callosotomy in Rett syndrome.

INTRODUCTION: Rett syndrome is a neurodevelopmental genetic disorder, characterized by developmental delay, hand stereotypies, abnormal gait, and acquired microcephaly. Epilepsy is very common in Rett syndrome and can be medically intractable. It remains uncertain if a patient with epileptic drop attacks associated with this genetic disease can benefit from corpus callosotomy. CASE REPORT: We report an 8-year-old girl with Rett syndrome and medically intractable epileptic drop attacks who underwent endoscopic total corpus callosotomy without any complications that led to the successful elimination of her seizures. CONCLUSION: Total corpus callosotomy is a feasible treatment option for medically intractable epileptic drop attacks in Rett syndrome and should not be considered as a contraindication in this condition. This is the first reported case of corpus callosotomy in Rett syndrome.

Frontal Lobe Decortication (Frontal Lobectomy with Ventricular Preservation) in Epilepsy-Part 1: Anatomic Landmarks and Surgical Technique.

BACKGROUND: An extensive frontal resection is a frequently performed neurosurgical procedure, especially for treating brain tumor and refractory epilepsy. However, there is a paucity of reports available regarding its surgical anatomy and technique. OBJECTIVES: We sought to present the anatomic landmarks and surgical technique of the frontal lobe decortication (FLD) in epilepsy. The goals were to maximize the gray matter removal, spare primary and supplementary motor areas, and preserve the frontal horn. MATERIAL AND METHODS: The anatomic study was based on dissections performed in 15 formalin-fixed adult cadaveric heads. The clinical experience with 15 patients is summarized. RESULT: FLD consists of 5 steps: 1) coagulation and section of arterial branches of lateral surface; 2) paramedian subpial resection 3 cm ahead of the precentral sulcus to reach the genu of corpus callosum; 3) resection of gray matter of lateral surface, preserving the frontal horn; 4) removal of gray matter of basal surface preserving olfactory tract; 5) removal of gray matter of the medial surface under the rostrum of corpus callosum. The frontal horn was preserved in all 15 patients; 12 patients (80%) had no complications; 2 patients presented temporary hemiparesis; and 1 Rasmussen syndrome patient developed postoperative fever. The best seizure control was in cases with focal magnetic resonance imaging abnormalities limited to the frontal lobe. CONCLUSION: FLD is an anatomy-based surgical technique for extensive frontal lobe resection. It presents reliable anatomic landmarks, selective gray matter removal, preservation of frontal horn, and low complication rate in our series. It can be an alternative option to the classical frontal lobectomy.

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

OBJECT: The authors undertook this study to review their experience with cortical resections in the rolandic region in children with intractable epilepsy. METHODS: The authors retrospectively reviewed the medical records obtained in 22 children with intractable epilepsy arising from the rolandic region. All patients underwent preoperative electroencephalography (EEG), MR imaging, prolonged video-EEG recordings, functional MR imaging, magnetoencephalography, and in some instances PET/SPECT studies. In 21 patients invasive subdural grid and depth electrode monitoring was performed. Resection of the epileptogenic zones in the rolandic region was undertaken in all cases. Seizure outcome was graded according to the Engel classification. Functional outcome was determined using validated outcome scores. RESULTS: There were 10 girls and 12 boys, whose mean age at seizure onset was 3.2 years. The mean age at surgery was 10 years. Seizure duration prior to surgery was a mean of 7.4 years. Nine patients had preoperative hemiparesis. Neuropsychological testing revealed impairment in some domains in 19 patients in whom evaluation was possible. Magnetic resonance imaging abnormalities were identified in 19 patients. Magnetoencephalography was performed in all patients and showed perirolandic spike clusters on the affected side in 20 patients. The mean duration of invasive monitoring was 4.2 days. The mean number of seizures during the period of invasive monitoring was 17. All patients underwent resection that involved primary motor and/or sensory cortex. The most common pathological entity encountered was cortical dysplasia, in 13 children. Immediately postoperatively, 20 patients had differing degrees of hemiparesis, from mild to severe. The hemiparesis improved in all affected patients by 3-6 months postoperatively. With a mean follow-up of 4.1 years (minimum 2 years), seizure outcome in 14 children (64%) was Engel Class I and seizure outcome in 4 (18%) was Engel Class II. In this series, seizure outcome following perirolandic resection was intimately related to the child's age at the time of surgery. By univariate logistic regression analysis, age at surgery was a statistically significant factor predicting seizure outcome (p < 0.024). CONCLUSIONS: Resection of rolandic cortex for intractable epilepsy is possible with expected morbidity. Accurate mapping of regions of functional cortex and epileptogenic zones may lead to improved seizure outcome in children with intractable rolandic epilepsy. It is important to counsel patients and families preoperatively to prepare them for possible worsened functional outcome involving motor, sensory and/or language pathways.

Role of the superior colliculus in the expression of acute and kindled audiogenic seizures in Wistar audiogenic rats.

PURPOSE: The role of the superior colliculus (SC) in seizure expression is controversial and appears to be dependent upon the epilepsy model. This study shows the effect of disconnection between SC deep layers and adjacent tissues in the expression of acute and kindling seizures. METHODS: Subcollicular transections, ablation of SC superficial and deep layers, and ablation of only the cerebral cortex were evaluated in the Wistar audiogenic rat (WAR) strain during acute and kindled audiogenic seizures. The audiogenic seizure kindling protocol started 4 days after surgeries, with two acoustic stimuli per day for 10 days. Acute audiogenic seizures were evaluated by a categorized seizure severity midbrain index (cSI) and kindled seizures by a severity limbic index (LI). RESULTS: All subcollicular transections reaching the deep layers of the SC abolished audiogenic seizures or significantly decreased cSI. In the unlesioned kindled group, a reciprocal relationship between limbic and brainstem pattern of seizures was seen. The increased number of stimuli provoked an audiogenic kindling phenomenon. Ablation of the entire SC (ablation group) or of the cerebral cortex only (ctx-operated group) hampered the acquisition of limbic behaviors. There was no difference in cSI and LI between the ctx-operated and ablation groups, but there was a difference between ctx-operated and the unlesioned kindled group. There was also no difference in cSI between SC deep layer transection and ablation groups. Results of histologic analyses were similar for acute and kindled audiogenic seizure groups. CONCLUSIONS: SC deep layers are involved in the expression of acute and kindled audiogenic seizure, and the cerebral cortex is essential for audiogenic kindling development.

Posterior quadrantic epilepsy surgery: technical variants, surgical anatomy, and case series.

OBJECTIVE: Patients with intractable epilepsy due to extensive lesions involving the posterior quadrant (temporal, parietal, and occipital lobes) form a small subset of epilepsy surgery. This study was done with a view to analyze our experience with this group of patients and to define the changes in the surgical technique over the last 15 years. We also describe the microsurgical technique of the different surgical variants used, along with their functional neuroanatomy. METHODS: In this series there were 13 patients with a median age of 17 years. All patients had extensive presurgical evaluation that provided concordant evidence localizing the lesion and seizure focus to the posterior quadrant. The objective of the surgery was to eliminate the effect of the epileptogenic tissue and preserve motor and sensory functions. RESULTS: During the course of this study period of 15 years, the surgical procedure performed evolved toward incorporating more techniques of disconnection and minimizing resection. Three technical variants were thus utilized in this series, namely, (i) anatomical posterior quadrantectomy (APQ), (ii) functional posterior quadrantectomy (FPQ), and (iii) periinsular posterior quadrantectomy (PIPQ). After a median follow-up period of 6 years, 12/13 patients had Engel's Class I seizure outcome. CONCLUSION: The results of surgery for posterior quadrantic epilepsy have yielded excellent seizure outcomes in 92% of the patients in the series with no mortality or major morbidity. The incorporation of disconnective techniques in multilobar surgery has maintained the excellent results obtained earlier with resective surgery.

Frontal decortication eliminates drug-induced ascorbic acid release in the striatum but not the nucleus accumbens of freely moving rats.

The mechanism of morphine-, methamphetamine-, and nicotine-induced ascorbic acid (AA) release in the striatum and nucleus accumbens (NAc) is not well understood. In the present study, the roles of the corticostriatal and corticoaccumbens pathways in drug-induced AA release were studied by using microdialysis coupled to high performance liquid chromatography with electrochemical detection (HPLC-ECD). The results showed that morphine (20 mg/kg), methamphetamine (3.0 mg/kg), or nicotine (1.5 mg/kg) intraperitoneally (i.p.) significantly stimulated AA release in the striatum to more than 180%, 190%, and 140% compared with saline groups, respectively. These effects could be completely eliminated by frontal decortication, or antagonized by MK-801 (1.0 mg/kg). Moreover, methamphetamine or nicotine also significantly induced AA release in the NAc to more than 180% and 150% compared with saline groups, respectively. However, these effects could not be eliminated by frontal decortication. Although the effects of methamphetamine or nicotine in the NAc could be antagonized by MK-801, two-way ANOVA analysis did not show a significantly interaction between MK-801 and methamphetamine, or nicotine. The results indicates that the corticostriatal glutamatergic pathway may be a common and necessary pathway in drug-induced AA release in the striatum, but the corticoaccumbens glutamatergic pathway may not be crucial in drug-induced AA release in the NAc. The present study implies that different mechanisms might be involved in drug-induced AA release in the striatum and the NAc in rats.

Egocentric spatial orientation in a water maze by rats subjected to transection of the fimbria-fornix and/or ablation of the prefrontal cortex.

The acquisition of a water maze based task requiring egocentric spatial orientation in the absence of distal cues was studied in four groups of rats: animals in which the fimbria-fornix had been transected, rats that received bilateral ablations of the anteromedial prefrontal cortex, animals in which both of these structures had been lesioned, and a sham-operated control group. Isolated lesions of both the anteromedial prefrontal cortex and the hippocampus were associated with a significantly impaired task acquisition. Both of these individually lesioned groups did, however, eventually demonstrate full functional recovery by reaching the task proficiency of the sham-operated control group. In contrast, the group in which both of these structures had been lesioned failed to demonstrate full functional recovery and was severely and long-lastingly impaired when compared to all other groups. Behavioural challenges in the form of a no-platform session and two reversals of platform position demonstrated that while the sham-operated control group and the group subjected to fimbria-fornix transections in isolation utilized rather pure egocentric orientation strategies, the two prefrontally lesioned groups (and especially the combined lesion group) employed a different set of solution strategies which at least partly relied on a "circling" method. Even in the behaviour of the prefrontally lesioned groups, however, indications of a certain level of cognitive representations of the platform positions were seen. It is concluded that both the prefrontal cortex and the hippocampus contribute to the mediation of egocentric spatial orientation. Furthermore, the hippocampus is a significant and potentially irreplaceable part of the neural substrate of functional recovery of the presently studied task after prefrontal lesions--while the prefrontal cortex may play a similar role with respect to hippocampal lesions.

Behavioral recovery and anatomical plasticity in adult rats after cortical lesion and treatment with monoclonal antibody IN-1.

We have previously reported that monoclonal antibody (mAb) IN-1 treatment after ischemic infarct in adult rats results in significant recovery of skilled forelimb use. Such recovery was correlated with axonal outgrowth from the intact, opposite motor cortex into deafferented subcortical motor areas. In the present study, we investigated the effects of mAb IN-1 treatment after adult sensorimotor cortex (SMC) aspiration lesion on behavioral recovery and neuroanatomical plasticity in the corticospinal tract. Adult rats underwent unilateral SMC aspiration lesion and treatment with either mAb IN-1 or a control Ab, or no treatment. Animals were then tested over a 6-week period in the skilled forelimb use task and the skilled ladder rung walking task. We found that animals treated with mAb IN-1 after SMC lesion fully recovered the use of forelimb reaching, but showed no improvement in digit grasping as tested in the skilled forelimb use task. The mAb IN-1 treatment group was also significantly improved as compared to control groups in the skilled ladder rung walking test. Furthermore, neuroanatomical tracing revealed a significant increase in the corticospinal projections into the deafferented motor areas of the spinal cord after mAb IN-1 treatment. These results indicate that treatment with mAb IN-1 after cortical aspiration lesion induces remodeling of motor pathways resulting in recovery in only certain behavioral tasks, suggesting that the cause of brain damage influences behavioral recovery after mAb IN-1 treatment.

Involvement of the cerebellum in classical fear conditioning in goldfish.

To investigate the emotional role of the cerebellum of fish, we conducted experiments examining effects of cerebellar manipulations on fear-related classical heart rate conditioning in goldfish. We performed total ablation of the corpus cerebelli to examine the effect of irreversible effects. We also performed localized cooling of the corpus cerebelli, in place of the ablation, for reversible inactivation of the cerebellar function. Both the cardiac arousal response to the first presentation of the conditioned stimulus and the cardiac reflex to the aversive unconditioned stimulus were not impaired by the ablation or cooling of the corpus cerebelli. On the other hand, inactivation of cerebellar function severely impaired the acquisition of a conditioned cardiac response in the fear-related conditioning. In addition, localized cooling of the corpus cerebelli reversibly suppressed the expression of established conditioned response. We suggest that the cerebellum of fish is not only being a motor coordination center but also is involved in emotional learning.

Functional reorganization of the motor cortex in adult rats after cortical lesion and treatment with monoclonal antibody IN-1.

We previously reported anatomical plasticity in the adult motor cortex after a unilateral sensorimotor cortex (SMC) lesion and treatment with monoclonal antibody (mAb) IN-1, which permits neurite outgrowth from the intact, opposite cortex into deafferented subcortical targets. This study was designed to investigate whether treatment with the mAb IN-1 after SMC lesion in the adult leads to functional reorganization of the intact, opposite motor cortex. Adult rats underwent unilateral SMC aspiration lesion and treatment with either mAb IN-1 or control antibody, or no treatment. After a 6 week survival period, the intact, opposite forelimb motor cortex was explored using intracortical microstimulation to evoke forelimb movements. A dramatic increase in ipsilateral movements of the lesion-impaired forelimb was found in animals treated with mAb IN-1 compared with control animals. These results resembled our previous findings of cortical reorganization in the spared hemisphere after neonatal cortical lesion and without any additional treatment. These results show that, after adult cortical lesion, treatment with mAb IN-1 induces a functional reorganization of the intact, opposite motor cortex.

Permanent or transitory effects on neurocognitive components of the CNV complex induced by brain dysfunctions, lesions and ablations in humans.

Since the mid-1960s, essentially using electrophysiological methods, our research group has examined the effects of different brain diseases in humans, both on first- and second-order conditioned responses and on some types of neurocognitive potentials of the CNV complex. This didactic lecture will focus on our various attempts to identify and understand the neuroanatomical and neurophysiological substrates involved in cognitive information processing followed by the conception and execution of sensory-motor and behavioural responses evoked by significant acoustic stimuli, in both pathological situations and normal control subjects. Great interest was, e.g. aroused in the early 1970s by the rare, fortunately unrepeatable, opportunity of examining the CNV patterns in various psychiatric patients treated with psychosurgical Freeman-Watts bilateral prefrontal 'radical' lobotomy, also with repeated recordings (The Responsive Brain (1976) 158; Multidisciplinary Perspectives in Event-Related Brain-Potentials Research (1978) 376) or bimedial bifrontal cingulotomy (Multidisciplinary Perspectives in Event-Related Brain Potential Research (1978) 383). In the same period, investigations into CNV activity recorded in patients submitted to complete callosotomy ('split brain': Attention and Performance, vol. IV (1972) 221; Electroenceph. Clin. Neurophysiol. Suppl. 33 (1973) 161) were also begun and were continued into the 1980s, also with regard to other types of ERP (Brain 111 (1988) 553; J. Cog. Neurosci. 2 (1990) 258). All these data furnished unique information about the sub-second dynamics of unilateral or bihemispheric cortico-cortical and cortico-subcortical interconnections in humans. In recent years, with a classic method of analysis based on sequential scalp-topographic bidimensional neuroelectric mapping and 21/19 electrodes connected to three different references, and binaural/monaural clicks as warning signals (S1), we have repeatedly examined the CNV activity of 11 selected patients submitted to complete ablation of the damaged cortical areas, with uni- or bilateral lesions restricted to the prefrontal or associative parieto-temporal areas. We have always used the standard CNV paradigm (S1-S2 motor-response) which evokes a complex of neurocognitive potentials, including the P300 from S1, which are well-known, since they are certainly among the most studied ERPs in the various ages and races of normal subjects, psychiatric patients and subjects with different brain diseases. The most important results have been, (1) In normal subjects the MRI and the latency differences of CNV component measurements along the bidirectional pathways functionally interconnecting ipsilateral distant associative cortical areas (e.g. the arcuate-superior longitudinal complex bundle) were accounted for by the transcortical conduction time, which varies in our scalp recordings from 1 cm/0.74 to 1.28 ms ( approximately 9.8 m/s). (2) Constantly, no true auditory S1-elicited N1a, b, c, P2, N2, P300 components or CNV slow waves (O- and E-wave) were recordable over the whole of the ablated cortical areas, but only clearly identifiable volume-conducted EP/ERPs generated in other hemispheric structures. (3) The post-S1 ERP/CNV complexes on the intact hemisphere were found to be within the normal limits. (4) Effects of severe disruption on the S1 ERP/CNV complexes evocable on the site and on remote ipsilateral apparently normal anatomo-functionally interconnected brain regions were observed in 5 patients, 4 of whom had extensive frontocortical ablations. In two of the latter the distant disruptive action on the CNV components over the neuroradiologically normal ipsilateral two-way connected post-rolandic sensory and association areas was seen to be partially reversible, showing aspects of a probable slowly evolving diaschisis-like effect. Similar deactivation of some ERP components was observed in reverse on the ipsilateral dorsolateral frontocortical region in the fifth patient with a large parieto-temporal cortex ablation. These data require confirmahese data require confirmation, and when this phenomenon is observable, it must be appropriately monitored with different methods of functional neuroimaging. This will serve not only for medical and neuropsychophysiological diagnosis purposes, but also particularly for a correct and really useful planning of neuro-rehabilitation activities in selected cases.

Pediatric peri-insular hemispherotomy.

A number of surgical procedures are available for patients with epilepsy associated with diffuse hemispheric disorders. In this report, 16 pediatric patients had hemispherectomy: 5 underwent hemidecortication and 11 had peri-insular hemispherotomy. The clinical records were retrospectively reviewed, and the results and complications of the procedures were documented. The procedure was feasible in very young children and in the absence of ventriculomegaly.

Loss of the innate cortical engram for action patterns used in skilled reaching and the development of behavioral compensation following motor cortex lesions in the rat.

Damage to the motor cortex of the rat (Rattus norvegicus) impairs skilled movements used in reaching for food with the contralateral forepaw. Nevertheless, there is substantial recovery in success over a two-week postsurgical period. The profile of behavioral recovery is believed to reflect the eventual normalization of behavior, but this idea has not been explicitly examined. The present experiments examined postsurgical reaching success and reaching movements as a function of (1) lesion type, (2) lesion size, (3) lesion location, (4) depletion of forebrain noradrenaline, and (4) presurgical and postsurgical experience. The results show that at least two separate processes contribute to recovery in postsurgical performance. The early postsurgical period was characterized by extreme difficulties in making reaching movements. The experiments suggest that this initial impairment was due to the loss of the innate cortical engram that supports the action patterns used for skilled movements. Subsequent recovery in reaching success was not due to the reacquisition of normal movements, but was due rather to the use of compensatory movements. The results are discussed in relation to the idea that true recovery from motor cortex injury will require that damaged neurons and their connections be rescued or replaced.

Use of the intracarotid amobarbital procedure in the evaluation of memory.

The intracarotid amobarbital procedure (IAP) involves the temporary inactivation of one cerebral hemisphere by the injection of sodium amobarbital, which allows independent testing of the contralateral hemisphere. Initially used for lateralization of language, IAP later found a role in the evaluation of memory function in patients with intractable temporal lobe epilepsy being considered for resective surgery. IAP technique varies widely across centers, but, in general, memory is assessed by presenting the patient with a number of items during the period of hemispheric inactivation and testing recall or recognition of these items after the effect of the drug has worn off. Because the medial temporal lobe is not directly perfused by the internal carotid artery, concerns have been raised about the ability of the IAP to test hippocampal memory function. Consequently, a variety of selective procedures have been devised. Findings on both intracranial EEG recordings and pathologic and neuroimaging studies support the association of IAP memory results with hippocampal function. The IAP memory test was originally designed to predict the risk for development of global amnesia following unilateral temporal lobectomy. More recently, it also has been used as an adjunct in lateralizing the seizure focus and for predicting postoperative selective memory deficits and seizure outcome.

Three-dimensional computer-assisted stereotactic-guided microneurosurgery combined with cortical mapping of the motor area by direct electrostimulation.

TIM (Zeppelin Chirurgische Instrumente GmbH, 82 049 Pullach, Germany) is a tomographic imaging system which enables surgeons to visualize the pathologic lesions three dimensionally in relationship to the surrounding structures. The distance and the angle between the pathologic lesion and the anatomical and/or bony landmarks as well as the volume of the mass lesion can be measured. Therefore an accurate localization of the lesion is possible with this technique. It is very applicable for planning of surgery on skull base tumors. The surgical procedure for small and well-defined, intrinsic pathologic deep-seated brain lesions, however, becomes much easier by using the stereotactic techniques of this system. The target point and the direction brain-surface-to-lesion can be determined within seconds. Before the aiming probe is inserted to the target, the cortical motor area is mapped by direct electrical stimulation. The approach can be varied depending on the results of these neurophysiologic investigations of the brain surface. The dissection is made along the aiming probe up to the target point. Because of the fixation of the brain with the needle, a brain shifting due to the dissection as well as to CSF release is diminished. Forty patients with deep-seated intracerebral lesions were operated on during a 13 months period by these combined techniques in our service. Using this technique, we never made a negative exploration. In all but three patients, total removal of the mass lesion was achieved. Permanent neurological deficits were observed in two patients only. In our opinion, this combined imaging and neurophysiological technique is easy to perform, and of major benefit for the patients due to its accuracy and is preferable in comparison with other single computer localizer techniques without neurophysiological monitoring.

Surgical treatment for epilepsy: a retrospective Swedish multicenter study.

The characteristics of patients suffering from drug resistant epilepsy, including the results of the preoperative evaluation and epilepsy surgery were retrospectively analyzed in a Swedish multicenter 10-year cohort of children and adults. Altogether 152 patients (65 children and 87 adults) treated during the period 1980-1990 in three epilepsy centers were included and followed-up 2 years after surgery. Median age at onset of seizures was 4 years for the children and 12 years for the adults. A localization related epilepsy was present in 85% of the children and in 95% of the adults. The mean number of seizure types in the children was 1.7 (range 1-4) and in the adults 1.8 (range 1-4). The median monthly seizure frequency was 52 and 15 for children and adults respectively. Resective surgery was performed in 143 cases (94 temporal, 31 extratemporal, 9 multilobar and 9 major resection procedures) and palliative procedures in 16 cases (13 callosotomies and 3 stereotactic amygdalotomies). Postoperative neurological deficits were detected in 9% of the patients after temporal lobe resections and in 15% of the patients after extratemporal and multilobar resection procedures. Two years after resective surgery 53% of the children and 49% of the adults were seizure free. Another 25% of the patients had a more than 50% reduction of seizure frequency. In the postoperative non seizure free group of patients there was a negative correlation between decrease in weighted seizure severity and decrease in seizure frequency. This finding stresses the need for including other parameters than seizure frequency when evaluating the outcome of epilepsy surgery.

Epilepsy surgery.

Surgical therapy of epilepsy, although still underutilized, is presently well accepted and performed world-wide with increasing frequency. In the last decade the following changes have been noticed: non-invasive pre-surgical evaluation is increasingly carried out in close collaboration with referring centres so that often no (or only a very short) hospitalization is necessary in highly specialized epilepsy centres for this purpose. Stereoelectro-encephalography (SEEG) is used less often in invasive evaluation while the subdural strip and grid electrode-techniques are used more often. There is a general trend for a more flexible and collaborative multidisciplinary and multi-method approach utilizing the whole spectrum of modern diagnostic facilities in a more patient-oriented and therefore more cost-effective way. The main objective of the pre-surgical evaluation is to determine the onset area of the patient's spontaneous habitual seizures. The primary epileptogenic zone is not necessarily synonymous with the so-called lesional zone, although in the great majority of patients they are related. In a small percentage of candidates for epilepsy surgery additional special examinations are necessary to prevent and/or predict the degree of post-operative deficits. At present selective Amytal tests are often used but these invasive procedures might be replaced in the future by functional PET and functional MR studies. Surgery in patients with epilepsy can be categorized into: (i) lesion-oriented surgery (lesionectomy sensu stricto), (ii) epilepsy-oriented lesional surgery, (iii) surgery for epilepsy sensu stricto. Surgery is performed with a 'curative (= causal)' or a 'palliative' intention. Furthermore surgery can be categorized into standardized epilepsy surgery (such as anterior temporal lobe resection, selective amygdalohippeocampectomy, anterior callosotomy); and individually tailored surgical interventions. It is obvious that also so-called standardized operations are tailored to some degree, usually based on pre-operative findings as well as on intraoperative corticography and/or other intra-operative neurophysiological tests (functional mapping). Individually tailored operations comprise smaller topectomies and larger resections. Surgery for temporal lobe epilepsy still prevails. For mesial temporal lobe epilepsy more selective operations, such as the selective amygdalohippocampectomy, are increasingly performed. Today the majority of patients suffering from this syndrome can be evaluated non-invasively (or 'semi-invasively' with the foramen ovale electrode technique) in combination with MRI (including volumetry of the hippocampus) and PET or SPECT. In general one has the impression that extratemporal resections without a lesion are performed less often. But, if a morphological abnormality is present, pre-surgical evaluation (using grids), and surgery making use of 'functional mapping' are increasingly offered from more and more centres. Anterior callosal sections and functional hemispherectomies have also witnessed a renaissance. The most important standardized operations are reviewed.

Hemispherectomy for seizures.

Hemispherectomy, or hemidecorticectomy as it is more accurately described, has been highly effective in reducing or eliminating medically intractable seizures associated with hemiplegia. Because of late onset postoperative superficial cerebral hemosiderosis and its associated neurologic deterioration, this procedure was all but abandoned for years. With improved surgical techniques and diagnostic testing, some medical centers with a special interest in epilepsy are again using hemispherectomy as a treatment for uncontrolled seizures associated with Rasmussen's encephalitis, as well as other etiologies. Specialized nursing care throughout the hospital course is essential to a positive outcome for the patient and family.