Efficacy and safety of radiosurgical callosotomy: a retrospective analysis

PURPOSE: Anterior callosotomy is a surgical option for the treatment of generalized tonic or atonic seizures associated with drop attacks. Besides open surgery, a radiosurgical callosal disconnection using the gamma knife (GK) also can be performed, but reliable data about tolerability and efficacy are sparse. METHODS: Eight patients (three female, five male age range, 5 to 69 years) with severe generalized epilepsy associated with disabling drop attacks underwent GK callosotomy between 1993 and 2004. In six patients, the anterior third of the corpus callosum was radiosurgically disconnected. In one patient a second procedure with GK treatment of the middle third of the corpus callosum was added 17 months later. In two patients posterior GK callosotomy had followed partial hemispherotomy. RESULTS: Drop attacks (DAs) were completely abolished in three patients, and two patients had a marked DA seizure reduction of 60%. Two of four patients with additional generalized tonic-clonic seizures showed a reduction of 100%, and the remaining, a 50% and 60% decrease, respectively. Other seizure types responded less well to the radiosurgical treatment. In both patients with posterior GK callosotomy after hemispherotomy, partial seizures decreased. Beside transient headache in two patients, no immediate or long-term postradiosurgical side effects were observed. CONCLUSIONS: Palliative radiosurgical callosotomy is an efficient and safe noninvasive alternative to the open procedure with comparable results. No signs of postradiosurgical side effects were noted within an up to 12-year posttreatment period.     

Corpus Callosotomy for Intractable Epilepsy: Seizure Outcome and Prognostic Factors

We reviewed the outcome of corpus callosal section in 64 adult and pediatric patients to identify factors associated with a good outcome: 48% of patients had a favorable outcome for overall seizure frequency. Improvement was noted in several seizure types and was most likely for drop attacks, particularly in the setting of a unilateral focal cerebral lesion or a true generalized epilepsy of Lennox-Gastaut type. Poor outcomes for drop attacks were more likely if there was associated severe intellectual handicap or bilateral independent spikes on interictal EEG. Complex partial seizures (CPS), most commonly of frontal lobe origin, also responded favorably. The complications of callosal section were usually mild and transient. New focal seizures occurred in only 2 patients and were not as frequent or disabling as preoperative seizure types. A worthwhile improvement in seizure outcome was achieved by completion of the callosotomy in 6 of 10 patients with unsatisfactory results from anterior callosotomy.     

Outcome and long term follow-up after corpus callosotomy in childhood onset intractable epilepsy

Introduction Epilepsy surgery is a standard of care in the treatment of medically intractable epilepsy. Twenty five percent of patients with intractable epilepsy in childhood can be candidates for epilepsy surgery. Corpus callosotomy is a surgical treatment option for patients with potentially injurious drop attacks and disabling generalized seizures. Postoperative improvement of cognition and speech are important gains after epilepsy surgery particularly during childhood. The aim of this study is to evaluate the outcome of corpus callosotomy for the treatment of childhood onset medically intractable epilepsy in a developing pediatric epilepsy surgery center.Method We report 16 patients who underwent two thirds anterior corpus callosotomy for treatment of refractory seizures in childhood.Results All patients had drop attacks or multiple types of seizures, yet some showed focal onset with secondary generalization on electroencephalogram (EEG). One patient was seizure free (class 1 outcome), five had class 2A outcome, five had class 2B outcome, and five had class 3 outcome. Overall 11/16 (69%) of our patients improved significantly after anterior callosotomy.Conclusion Corpus callosotomy remains to be a fairly good choice of surgical treatment for childhood onset medically intractable epilepsy in selected patients.     

Corpus callosotomy

Corpus callosotomy is a palliative surgical procedure that is suitable for some patients with intractable seizures who are not candidates for focal resective surgery. The rationale for this procedure is based on the hypothesis that the corpus callosum is a critical pathway for interhemispheric spread of epileptic activity. Efficacy and relatively low permanent morbidity in corpus callosotomy for medically intractable epilepsy have been demonstrated by more than six decades of experience. Callosotomy best ameliorates drop attacks (tonic and atonic seizures), though tonic-clonic, absence, and frontal lobe complex partial seizures often respond as well. In addition to seizure reduction, behavior and quality of life may improve. Hence, callosotomy is justified as a therapy for appropriate patients with intractable epilepsy.     

The utility of diffusion tensor imaging tractography for post-operative evaluation of a patient with hemispherotomy performed for intractable epilepsy

Hemispherotomy is an effective treatment for patients with severe epilepsy caused by hemispheric abnormalities such as hemimegalencephaly or other dysplastic malformations. Here, we report a 5-year-old boy who experienced right-side hemiconvulsion due to left hemispheric cortical dysplasia. He presented with mild right hemiparesis that had been present since seizure onset. Ictal electroencephalogram obtained during the hemiconvulsion showed localized epileptic discharges in the left hemisphere. He underwent a left peri-insular hemispherotomy. Three months after surgery, clonic convulsions returned in the left leg and EEG-video monitoring showed localized epileptic discharges in the frontal region. Magnetic resonance images showed that the genu of corpus callosum was unsectioned and diffusion tensor imaging tractography confirmed the presence of callosal fibers in the genu of the corpus callosum. Clonic convulsion disappeared after additional section of the corpus callosum. Further studies are warranted to determine the utility of diffusion tensor imaging tractography on the assessment of subcortical fibers following disconnective epilepsy surgery.     

Surgical treatment for pediatric intractable epilepsy--focusing on modified functional hemispherectomy in infants

Our experience with modified functional hemispherectomy in 14 infants are presented. The etiology of intractable epilepsy was cortical dysgenesis in all of the cases. We applied our new surgical method, transopercular hemispherotomy, in which the frontal operculum was resected en bloc including the upper half of the insula. The corpus callosum was totally sectioned through the lateral ventricle. The resection cavity was communicated to the inferior ventricle, and the medial temporal structures were resected. Finally, the horizontal fibers emerging from the frontal lobe were sectioned along the posterior edge of the ala minor ossis sphenoidalis. There was no mortality or morbidity during and immediately after operation. In 12 cases with more than 1 year follow-up, remarkable seizure reduction was obtained in 75% of the cases and worthwhile improvement in the remaining 25%. No major complications were encountered, except for hydrocephalus in 3 cases and incomplete section of the callosum in 3. In cases showing catch-up of psychomotor development after surgery, swelling of the unaffected hemisphere was observed.     

Outcome following corpus callosotomy

Although corpus callosotomy has been performed since 1940 to treat severe medically intractable seizures, there remains controversy as to when, or even if, the surgery should be done. Unlike most surgical therapies for epilepsy where the epileptic focus is removed, corpus callosotomy interrupts the propagation of epileptic discharges. The procedure is primarily used in patients with secondarily generalized seizures with or without drop attacks in whom focal resection is not possible. The goal of this surgery is to improve functioning and well-being. In this study, we retrospectively reviewed records from 28 patients undergoing corpus callosotomy to assess improvement following surgery. Parents and patients were also sent a questionnaire to assess quality of life. While surgery reduced the frequency of seizures, definite improvements in quality of life were limited only to patients with frequent daily drop attacks preoperatively. We believe corpus callosotomy offers a significant improvement of both seizure control and quality of life in children with frequent drop attacks of tonic, myoclonic, or atonic origin.     

Neuronal Disconnection for the Surgical Treatment of Pediatric Epilepsy

Summary: The surgical methods and results of disconnective surgery for pediatric epilepsy were retrospectively analyzed. The techniques of neuronal disconnection included multiple subpial resection (MST), corpus callosotomy, and functional hemisphercctomy by disconnection. Of 158 total pediatric operations, disconnective techniques were employed in more than 60% of the cases. MST was applied when the epileptic focus was located in unresectable cortices such as speech or motor areas. MST was also instrumental when the epileptogenic zone was extensive and was widely disseminated, as is often observed in cases of neocortical epilepsy. Of 25 patients who underwent MST, surgical outcomes after > 1 year follow-up showed Engel Class I or II in 10 cases, Class III in 12, and Class IV in 3. No mortality or morbidity was encountered during surgery or postoperatively. Corpus callosotomy was applied to cases of disabling generalized seizures and showed a marked effect in alleviating potentially injurious drop attacks. Of 34 patients with drop attacks, 29 became free from this type of seizure, 4 had infrequent attacks, and only 1 showed no beneficial effect. Postoperative improvement of cognition and speech was recognized in 77% of the cases. We developed a new method of functional hemispherectomy by fiber disconnection and applied this less invasive technique to 23 cases of hemispheric lesions. Of the 17 cases with > 1 year follow-up, 13 were in Class I or II, and 3 in Class III, and 2 in Class IV. Development partially normalized in infants with good seizure outcomes.     

Surgical outcome of corpus callosotomy in patients with drop attacks

PURPOSE: We examined presurgical factors that independently influence surgical outcome after corpus callosotomy. For adequate measurement of the surgical outcome, we analyzed seizure outcome of drop attacks, postoperative overall daily function, and family satisfaction. METHODS: At least 2 years after callosotomy (mean, 40.0 months), we retrospectively investigated 52 patients with drop attacks. As presurgical factors, we analyzed the age at surgery, age at seizure onset, age at drop attack onset, sex, hemiparesis, severe mental retardation, EEG abnormality, MRI abnormality, and extent of callosal section (total or partial callosotomy). Stepwise logistic regression was used for analysis. RESULTS: Satisfactory outcome (seizure cessation or >90% seizure reduction) was achieved in 85% of patients with drop attacks, 32% of those with generalized tonic seizures, and 31% of those with generalized tonic-clonic seizures. The families assessed the overall daily function as improved in 62% of patients, unchanged in 23%, and impaired in 15%. Family satisfaction with callosotomy was achieved in 83% of patients (definitely satisfied, 39%, somewhat satisfied, 44%). Total callosotomy is independently predictive of satisfactory reduction of drop attacks (p = 0.013). A younger age is independently predictive of improvement of overall daily function (impaired and improved: p = 0.004) and family satisfaction (unsatisfied and somewhat satisfied, p = 0.018; unsatisfied and definitely satisfied, p = 0.0006). CONCLUSIONS: In the present study, we found that total callosotomy is more effective for treatment of drop attacks than partial callosotomy and that children receive more benefit than adults after callosotomy.     

Outcome after corpus callosotomy in children with injurious drop attacks and severe mental retardation

Wide variability in patient selection, extent of callosal section and definition of successful outcome between studies make impact of corpus callosotomy on patients with medically refractory epilepsies difficult to interpret. Severe mental retardation is considered to be predictive of unfavorable seizure outcome after callosotomy. Very little attention has been paid on the influence of callosotomy on the psychosocial burden on the patients' families. We evaluated the seizure outcome, and parental perception about change in cognition and behavior of 17 children (median age 9.5 years, range 3.5-18 years) with severe mental retardation (IQ<30 in all, except one) and injurious drop attacks, who have completed >or=1-year postoperative follow-up after callosotomy. Nearly two-thirds of our patients had >or=90% reduction in drop attacks and generalized tonic-clonic seizures. In the one-stage total callosotomy group, 9 of 11 (82%) patients had favorable outcome, compared to 2 of the 6 (33%) in the partial callosotomy group. Absence of generalized epileptiform discharges on the 1-year postoperative EEG was significantly associated with a favorable seizure outcome. The mean duration of epilepsy prior to callosotomy tended to be shorter among patients with favorable seizure outcome. Postoperative complications were trivial and transient. Nearly three-fourths of the parents appreciated improvements in behavior and attentiveness of their children and were satisfied with the outcome. We conclude that, in children with severe mental retardation and injurious drop attacks, total callosotomy can be undertaken as a one-stage procedure with insignificant morbidity and results in highly favorable seizure outcome.     

Callosotomy in Children: Experience in the Veterans General Hospital-Taipei

Purpose : Surgery is becoming more important for the treatment of chronic seizures in the pediatric age group. Common surgical procedures in children include anterior callosotomy and resection of focal lesions and surrounding tissue.
Methods : The underlying diseases or pathologies for the chronic seizures of children included cryptogenic epilepsy, tumors, vascular lesions, dysplasia, and posttraumatic or ischemic events. Anterior callosotomy was performed, mainly for Lennox-Gastaut syndrome. Patients with intractable secondarily generalized or generalized seizures were referred to the Hospital and selected for presurgical evaluation. Until 1996, 82 callosotomies had been performed. The surgical technique consisted of dissecting and splitting the anterior two thirds to four fifths of the corpus callosum through a frontal interhemispheric approach. Intraoperative precallosotomy and postcallosotomy electrocorticography (ECoG) studies were performed.
Results : The mean age at the time of the operation was 8 years. The mean duration of the seizures was 5.3 years. There was no operative mortality or significant neurologic complications. With a mean follow-up period of 1.9 years, the outcome was that 20.7% of the children were seizure free, and 41.5% showed a significant improvement.
Conclusions : Sixty-three percent of the parents were satisfied with the results. Some children showed an improvement in their hyperactivity, attention span, and social skills. However, there was no help for their mental retardation.     

Parental Assessment of Functional Outcome After Corpus Callosotomy

Summary: Purpose : We wished to evaluate functional outcome and parental satisfaction after corpus callosotomy.
Methods : We studied a cohort of parents of 17 patients who had received an anterior corpus callosotomy > 7 months earlier (mean 26 months) for severe, intractable seizures. Parental satisfaction with the overall surgical results was the primary outcome measure. In addition, the parents assessed behavior changes that had been emphasized preoperatively as important aspects of their children's function, including alertness and responsiveness, falls and injuries, and special care needs. Degree of seizure reduction and extent of corpus callosum were also measured.
Results : The parents of 15 (88%) patients reported satisfaction with the surgical outcome. All parents who expressed satisfaction would recommend callosotomy to another family in a similar situation. The behavior change most closely associated with satisfaction was improved alertness and responsiveness (p < 0.03). Although 9 patients experienced > 80% reduction in targeted seizures, satisfaction was not reported at a greater rate as compared with the 6 patients with 50–80% reduction.
Conclusions : Most parents report satisfaction with the outcome of their child's corpus callosotomy, but are influenced by improvement in aspects of function and behavior in addition to seizure reduction.     

Corpus callosotomy in a patient of hemimegalencephaly and Lennox-Gastaut syndrome

We report the case of a girl with hemimegalencephaly (HME) and Lennox-Gastaut syndrome (LGS) treated by callosotomy at 1 year of age. Over 10 years, her seizure frequency and severity decreased markedly. Hemispherectomy is the main surgical option for HME although HME appears to correlate with a less favorable seizure outcome. However, the clinical presentation of LGS and possible generalized cortical dysplasia, which is indicative of a secondarily generalized epilepsy, might predict a favorable surgical outcome of corpus callosotomy in patients of HME, as in our case.     

Effective posterior extension of callosotomy by gamma knife surgery

Drop attacks are the most responsive seizure type to open callosotomy, however, surgical complications can worsen the prognosis. Various less invasive techniques have been explored in an effort to minimize the risk. We present a patient who suffered from life‐threatening traumatizing drop attacks in whom previous open anterior callosotomy and vagal nerve stimulation were unsatisfactory. Following posterior extension of the callosotomy by non‐invasive gamma knife surgery, the rate of drop attacks declined from 30 a day to once a day, or every few days over a four‐month period, without complications. Open callosotomy is an invasive and high risk treatment option for patients with drop attacks. The procedure has a potential for complications and neurological consequences that can worsen the functional capacity of a patient who already suffers with disability. Recently, in an attempt to decrease the invasiveness associated with this technique, additional technical refinements and less invasive procedures have been explored in a few studies. Here, we report a case of refractory epilepsy with life‐threatening traumatizing DA, in which the patient was treated by radiosurgical posterior callosotomy after unsatisfactory open anterior callosotomy and vagal nerve stimulation.     

Callosotomy for epilepsy after West syndrome

PURPOSE: To analyze the results of callosotomy in 17 children with symptomatic generalized epilepsy after West syndrome, according to the different seizure types and surgical procedures, to define selection criteria for candidates to callosotomy. METHODS: Callosotomy was performed in two successive stages. Partial callosotomy, anterior in 13 and posterior in three, was followed by completion in 14 cases in all but four patients (complete callosotomy in one stage in one, no completion in three). All patients had clinical, video-EEG, and neuropsychological evaluation before and after each stage of callosotomy, with a mean final follow-up of 4 years. RESULTS: Seizure frequency improved in only two of 13 patients after anterior callosotomy, in none of three after posterior callosotomy, but in nine of 14 after complete callosotomy. After complete callosotomy, spasms disappeared in 80% of the cases, and drop attacks, the most severe ictal event, completely stopped or were dramatically reduced in 90% of the children. One patient no longer had episodes of status epilepticus, and another one acquired the ability to walk after complete callosotomy. From the cognitive viewpoint, nine patients with improved seizure frequency after complete callosotomy also had improved behavior and cognitive functions, but two others experienced speech deterioration after posterior callosotomy at age 11 years and completion of callosotomy at age 16 years. CONCLUSIONS: As in other severe generalized epilepsies in childhood, drop attacks provide the best indication for complete callosotomy in patients with previous West syndrome. Because drop attacks can be identifiable by falls only, the previous acquisition of walking should be considered as a key feature for any benefit to be obtained.     

Long-term follow-up of seizure outcomes after corpus callosotomy

PurposeCorpus callosotomy can be an effective surgical treatment for medically intractable generalized seizures, particularly for drop attacks. We studied long-term seizure outcomes after callosotomy, mainly focusing on drop attacks as the seizure type.MethodsThis study reviews 78 patients who underwent callosotomy and were followed up for more than 3 years after surgery. Seizure outcome of callosotomy was analyzed for seizure type, including drop attacks and other types of seizures.ResultsThe followed-up time ranged from 3 to 13 years (mean; 7.0 ± 2.9 years, median; 8 years). When callosotomy was total section, drop attack seizure-free rate was 90%. However, partial section yielded a drop seizure-free rate of only 54%. Thirty-five of the 46 (76%) patients who were free of drop attacks 6 years after callosotomy had no relapse thereafter. Relapse of drop attacks was also significantly different depending on the range of callosotomy. With total section, only 7% showed relapse of drop attacks. On the contrary, patients with partial section had a 31% relapse rate. In 21% patients, postural seizures newly developed after callosotomy.ConclusionsThese findings confirmed that callosotomy is the treatment of choice for disabling generalized seizures, especially for drop attacks. Total section is far more effective than partial section in terms of control of drop attacks and prevention of seizure relapse. However, new types of seizure could occur after callosotomy. When newly developed postural seizures were very severe, patients may fall due to sudden torsion of body, but the entire process of falling was not as sudden as that observed during previous drop attacks.     

Startle Epilepsy with Infantile Hemiplegia: Report of Two Cases Improved by Surgery

Summary: Purpose : To study the effectiveness of surgical therapy on 2 patients with startle epilepsy with infantile brain damage (SEIBD), a rare but distinctive epileptic syndrome characterized by motor seizures resistant to antiepileptic drugs (AEDs).
Methods: The patients with SEIBD both had hemiplegia, due to gross contralateral hemispheric lesions, and suffered from tonic postural seizures, frequently provoked by sudden unexpected somatosensory stimuli on the paretic side of the body. These attacks occasionally caused the patients to drop to the floor, and mild-to-moderate injuries had been sustained; they were resistant to all currently available AEDs. Consequently, these daily drop attacks severely restricted the patients' social lives and school participation. Both patients underwent corpus callosotomy and resection of epileptogenic premotor and supplementary motor lesions. One patient also underwent additional multiple subpial transections of the primary sensorimotor area.
Results: Seizures, as well as quality of life, improved dramatically in both patients after surgery.
Conclusions: Startle epilepsy with infantile hemiplegia is distinct epileptic syndrome characterized by structural brain damage restricted primarily to one hemisphere, large ipsilateral epileptogenic lesions involving the perisensorimotor area, refractory startle-provoked drop attacks, and a good response to epilepsy surgery.     

Surgical treatment for intractable epilepsy]

Epilepsy surgery can be divided into two categories, resective and disconnective procedures. The former includes lesionectomy, corticectomy, and lobectomy. The latter comprises MST (multiple subpial transection), corpus callosotomy, and hemispherotomy. In this presentation, the preoperative diagnosis and surgical outcomes of temporal lobectomy and MST will be illustrated. Temporal lobe epilepsy is one of the most common seizures in adult intractable epilepsy. Noninvasive preoperative evaluation, including analysis of seizure semiology, repetitive scalp EEG, and MR imaging, can definitely localize the seizure focus, without depending on invasive monitoring, in 70% of the cases. Seizure outcome after temporal lobectomy is generally satisfactory, with 70% seizure-free and > 90% significantly improved. However, verbal amnesia is an unavoidable sequela when the focus is on the speech-dominant side and preoperative MRI reveals little or no hippocampal atrophy. MST is an epoch-making surgical technique by which surgical treatment of eloquent cortex has become possible. In cases with neocortical epilepsy treated by MST alone or combined with corticectomy, 80% showed significant improvement, that is compatible with reported outcomes of corticectomy. MST can be also applied to treatments of extensive epileptic foci, Rasmussen's encephalitis, or Landau-Kleffner syndrome.     

Parental satisfaction and seizure outcome after corpus callosotomy in patients with infantile or early childhood onset epilepsy

PurposeTo elucidate the benefit of corpus callosotmy in terms of parental satisfaction and seizure outcome.MethodThis study included 16 consecutive patients with infantile or early childhood onset epilepsy who underwent total corpus callosotomy for alleviation of seizures. Questionnaires were sent anonymously to the parents asking about relative changes in seizures and about parental satisfaction for the post-operative outcome.ResultsThe improvements in frequency, intensity, and duration of seizures were correlated with the level of satisfaction (Spearman's rank-order correlation coefficient, ρ = 0.87, 0.93, and 0.75, respectively). The highest level of satisfaction was only seen in patients who achieved freedom from all seizures or drop attacks.ConclusionComplete seizure freedom and freedom from drop attacks are important goals of corpus callosotomy for parental satisfaction. These factors should be considered in assessing post-operative outcome after corpus callosotomy.     

Corpus callosotomy versus vagus nerve stimulation for atonic seizures and drop attacks: A systematic review

Atonic seizures are debilitating and poorly controlled with antiepileptic medications. Two surgical options are primarily used to treat medically refractory atonic seizures: corpus callosotomy (CC) and vagus nerve stimulation (VNS). However, given the uncertainty regarding relative efficacy and surgical complications, the best approach for affected patients is unclear. The PubMed database was queried for all articles describing the treatment of atonic seizures and drop attacks with either corpus callosotomy or VNS. Rates of seizure freedom, > 50% reduction in seizure frequency, and complications were compared across the two patient groups. Patients were significantly more likely to achieve a > 50% reduction in seizure frequency with CC versus VNS (85.6% versus 57.6%; RR: 1.5; 95% CI: 1.1–2.1). Adverse events were more common with VNS, though typically mild (e.g., 22% hoarseness and voice changes), compared with CC, where the most common complication was the disconnection syndrome (13.2%). Both CC and VNS are well tolerated for the treatment of refractory atonic seizures. Existing studies suggest that CC is potentially more effective than VNS in reducing seizure frequency, though a direct study comparing these techniques is required before a definitive conclusion can be reached.