Temporal lobe resections

Temporal lobe resective surgery for medically intractable epilepsy: a review of complications and side effects

Object. It is widely accepted that temporal resective surgery represents an efficacious treatment option for patients with epilepsy of temporal origin. The meticulous knowledge of the potential complications, associated with temporal resective procedures, is of paramount importance. In our current study, we attempt to review the pertinent literature for summating the complications of temporal resective procedures for epilepsy. Method. A PubMed search was performed with the following terms: “behavioral,” “cognitive,” “complication,” “deficit,” “disorder,” “epilepsy,” “hemianopia,” “hemianopsia,” “hemorrhage,” “lobectomy,” “medial,” “memory,” “mesial,” “neurobehavioral,” “neurocognitive,” “neuropsychological,” “psychological,” “psychiatric,” “quadranopia,” “quadranopsia,” “resective,” “side effect,” “surgery,” “temporal,” “temporal lobe,” and “visual field.” Results. There were six pediatric, three mixed-population, and eleven adult surgical series examining the incidence rates of procedure-related complications. The reported mortality rates varied between 0% and 3.5%, although the vast majority of the published series reported no mortality. The cumulative morbidity rates ranged between 3.2% and 88%. Conclusions. Temporal resective surgery for epilepsy is a safe treatment modality. The reported morbidity rates demonstrate a wide variation. Accurate detection and frank reporting of any surgical, neurological, cognitive, and/or psychological complications are of paramount importance for maximizing the safety and improving the patients' overall outcome.

Long-term seizure outcome following resective surgery for epilepsy: to be or not to be completely cured?

Surgical intervention is expected to improve the quality of life in patients with intractable epilepsy by providing adequate seizure control. Although many previous studies showed various rates of seizure freedom, definite conclusions have not yet been made regarding outcomes. In order to clarify the long-term postoperative outcome for a period up to 10 years, a retrospective review of our patients was performed longitudinally by using the survival analysis method. The postoperative state of epilepsy in 76 patients who underwent resection surgery was assessed based on Engel’s criteria. In addition, Kaplan-Meier survival analysis was used to calculate the probability of seizure freedom. In this patient group, abnormal lesion were detected by MRI in 70 out of 76 cases, and the ictal onset zone was finally identified within temporal lobe in 51 cases. The most favorable outcome, defined as Engel Class Ia, was observed in 26 (37%), 24 (40%), and 18 (41%) cases at 2, 5, and 10 years after surgery, respectively. The Kaplan-Meier survival curve in the overall group estimated the probability of seizure freedom as 75% (95% confidence interval [CI] 70–80%), 67% (62–72%), and 51% (45–57%) at 2, 5, and 10 years follow up, respectively. Half of all seizure recurrences occurred within the first 2 postoperative years. In this study, we showed that long-term favorable outcome of seizure control following resection surgery can be achieved in more than half of the patients.

Pediatric temporal lobe epilepsy surgery: resection based on etiology and anatomical location

Advances in electrophysiological assessment with improved structural and functional neuroimaging have been very helpful in the use of surgery as a tool for drug-resistant epilepsy. Increasing interest in epilepsy surgery has had a major impact on adult patients; a refined evaluation process and new criteria for drug resistance combined with refined surgical techniques resulted in large surgical series in many centers. Pediatric surgery has lagged behind this evolution, possibly because of the diverse semiology and electrophysiology of pediatric epilepsy obscuring the focal nature of the seizures and frustrating the treatment of catastrophic epileptic syndromes specific to children. Unfortunately, refractory -epilepsy is more -devastating in children than in adults as it interferes with all aspects of neural development. Nevertheless, during the last few decades, the efforts of a small number of centers with encouraging results in pediatric epilepsy surgery have motivated pediatric neurologists to gain interest. Although well behind in the number of patients compared with that of adults, pediatric series are increasing exponentially. While temporal lobe epilepsy is the focus of interest in adults, with almost 70 % of resections in the temporal lobe, the pediatric epilepsy spectrum is different. Resective or functional surgery techniques devoted to resistant extratemporal epilepsy are the major improvements in pediatric epilepsy surgery. Temporal lobe epilepsy in adults has been studied extensively but only recently has begun to receive attention in children. Several aspects of temporal lobe epilepsy in childhood remain unclear or controversial in terms of seizure semiology and its pathology. This is reflected in the surgical treatment. Information on the major contributors to a favorable outcome, such as type or extent of resection, in terms of seizure control and morbidity is not available as in adult temporal lobe epilepsy. This chapter discusses the major discrepancies between adult and pediatric temporal lobe epilepsy and outlines the current concepts in surgical treatment. The resection strategy based on the different substrates at different locations in the temporal lobe causing seizures is emphasized with respect to available literature.

Epilepsy surgery of the temporal lobe in pediatric population: a retrospective analysis

BACKGROUND

There is still some reluctance to refer pediatric patients for epilepsy surgery, despite evidence of success in retrospective series.

OBJECTIVE

To describe surgical experience and long-term outcome in pediatric temporal lobe epilepsy (TLE) at a single institution.

METHODS

Retrospective review of pediatric (<18-years-old) TLE patients who underwent surgery between November 1996 and December 2006 at Cleveland Clinic Epilepsy Center. Cox proportional hazard modeling was used to assess outcome predictors.

RESULTS

One hundred thirty pediatric patients met study criteria. Mean time between seizure onset and surgery was 6.3 years. Invasive evaluation was used in 32 patients (24.5%). Hippocampal sclerosis was present in 70 patients (53.8%), either alone or associated in dual pathology. The complication rate was 7%. The seizure-freedom rates at 1, 2, 5, and 12 years were 76%, 72%, 54%, and 41%, respectively (Kaplan-Meier). With the use of the Engel outcome classification, 98 (75.3%) patients were class I, 11 (8.5%) class II, 9 (7%) class III, and 12 (9.2%) were class IV at last follow-up. Only 4 (3.1%) patients underwent reoperations. Antiepileptic drugs (AEDs) were discontinued in 36 patients (28.3%) in a mean period of 18 months (SD ± 17 months; range, 6-102 months). Although left-sided resection, lower number of preoperative AED trials (≤ 4), and tumor pathology correlated with favorable seizure outcomes, extensive surgical resection remained the only significant outcome predictor after multivariate analysis (P = .007; HR = 0.13 [95% confidence interval 0.007-0.64]).

CONCLUSION

Careful selection of surgical candidates by multidisciplinary evaluations is required. Long-term seizure control is achieved successfully with acceptable low complication rates.

Magnetic resonance imaging in epilepsy

With a major role in revealing epileptogenic lesions, magnetic resonance imaging (MRI) has also been very helpful in surgical planning and postoperative follow-up of drug-resistant focal epilepsies. In this article, in addition to discussing the most common epileptogenic lesions, advanced quantitative and functional MRI techniques in detecting abnormalities and revealing hemodynamic and microstructural changes are emphasized.

Refractory epilepsy and deep brain stimulation

Up to one-third of all patients with epilepsy have epilepsy refractory to medical therapy. Surgical options include temporal lobectomy, focal neocortical resection, stereotactic lesioning and neurostimulation. Neurostimulatory options comprise vagal nerve stimulation, trigeminal nerve stimulation and deep brain stimulation (DBS). DBS enables structures in the brain to be stimulated electrically by an implanted pacemaker after a minimally invasive neurosurgical procedure and has become the therapy of choice for Parkinson's disease refractory to or complicated by drug therapy. Here we review DBS for epilepsy, a powerful emerging treatment in the surgical armamentarium for drug refractory epilepsy, with a focus on extratemporal epilepsy.

Outcomes of epilepsy surgery in adults and children

Surgery is widely accepted as an effective therapy for selected individuals with medically refractory epilepsy. Numerous studies in the past 20 years have reported seizure freedom for at least 1 year in 53-84% of patients after anteromesial temporal lobe resections for mesial temporal lobe sclerosis, in 66-100% of patients with dual pathology, in 36-76% of patients with localised neocortical epilepsy, and in 43-79% of patients after hemispherectomies. Reported rates for non-resective surgery have been less impressive in terms of seizure freedom; however, the benefit is more apparent when reported in terms of significant seizure reductions. In this Review, we consider the outcomes of surgery in adults and children with epilepsy and review studies of neurological and cognitive sequelae, psychiatric and behavioural outcomes, and overall health-related quality of life.

[Corticectomy: technical considerations]

The surgical treatment of epilepsy requires careful preparation and presents a certain number of technical specificities. The neurosurgeon must master not only the technical aspects but also the therapeutic and functional trade-off in order to modulate the procedure according to morphological and electrophysiological intraoperative data. A large number of technical variants have been developed to correspond to epileptological or functional anatomical considerations. Until this point, the choice of a particular technique does not seem to have a significant impact on the therapeutic effectiveness of surgery, and differences in results can be related to the presurgical evaluation and surgical indications. On the other hand, technical development promises to play an important role in limiting the long-term neurocognitive consequences of surgery.