Vascular malformations and epilepsy: clinical considerations and basic mechanisms

The outlook for adults with epileptic seizure(s) associated with cerebral cavernous malformations or arteriovenous malformations

Cerebral cavernous malformations (CCMs) and arteriovenous malformations (AVMs) are common: their asymptomatic prevalence on brain magnetic resonance imaging (MRI) is 1 in 625 and 1 in 2,000, respectively. The risk of epileptic seizure(s) for people with AVMs and CCMs affects their domestic, social, and professional lives, and may influence their decisions about treatment. This article summarizes the seizure risks for people with AVMs and CCMs, gleaned from published original articles indexed in OVID Medline and Embase before 1 January 2012. In the absence of prior intracranial hemorrhage and nonhemorrhagic focal neurologic deficit, a population-based study in Scotland, United Kingdom, found that the 5-year risks of first seizure were 8% for AVM and 4% for CCM; presentation with intracranial hemorrhage or focal neurologic deficit raised this risk for AVM (23%) but not for CCM (6%). Features associated with the occurrence of epileptic seizures for CCM are lesion multiplicity and cortical CCM location, whereas for AVM the most consistently reported associations are younger age, temporal location, cortical involvement, and nidus diameter >3 cm. In the absence of prior intracranial hemorrhage and nonhemorrhagic focal neurologic deficit, the 5-year risk of developing epilepsy following a first seizure is 58% for AVM and 94% for CCM, though there is no difference in the chance of achieving 2-year seizure freedom in this time frame (45% AVM vs. 47% CCM). Observational case series describe encouraging differences in seizure frequency before and after AVM and CCM treatment, but the shortage of studies demonstrating dramatic effects in comparison to concurrent control groups justifies the need for more controlled studies, ideally with randomized treatment allocation when the benefits of AVM or CCM treatment are uncertain.

Seizure predictors and control after microsurgical resection of supratentorial arteriovenous malformations in 440 patients

BACKGROUND

Seizures are a common symptom of supratentorial arteriovenous malformations (AVMs), and uncontrolled epilepsy can considerably reduce patient quality of life. Potential risk factors for epilepsy in patients with AVMs are poorly understood, and the importance of achieving freedom from seizures in their surgical treatment remains underappreciated.

OBJECTIVE

To characterize risks factors for preoperative seizures and factors associated with postoperative freedom from seizures in patients with surgically resected supratentorial AVMs.

METHODS

We analyzed prospectively collected patient data for 440 patients who underwent microsurgical resection of supratentorial AVMs at our institution.

RESULTS

Among 440 patients with supratentorial AVMs, 130 (30%) experienced preoperative seizures, and 23 (18%) with seizures progressed to medically refractory epilepsy. Seizures were associated with a history of AVM hemorrhage (relative risk, 6.65; 95% confidence interval [CI], 3.81-11.6), male sex (relative risk, 2.07; 95% CI, 1.26-3.39), and frontotemporal lesion location (relative risk, 1.75; 95% CI, 1.05-2.93). After resection, 96% of patients had a modified Engel class I outcome, characterized by freedom from seizures (80%) or only 1 postoperative seizure (16%; mean follow-up, 20.7 ± 2.3 months). Comparable rates of postoperative seizures were seen in patients with (7%) or without (3%) preoperative seizures. AVMs with deep artery perforators were significantly associated with postoperative seizures (hazard ratio, 4.35; 95% CI, 1.61-11.7).

CONCLUSION

In the microsurgical treatment of supratentorial AVMs, hemorrhage, male sex, and frontotemporal location are associated with higher rates of preoperative seizures, whereas deep artery perforators are associated with postoperative seizures. Achieving freedom from seizure is an important goal that can be achieved in the surgical treatment of AVMs because epilepsy can significantly diminish patient quality of life.

Cliniconeuropathologic correlations show astroglial albumin storage as a common factor in epileptogenic vascular lesions

PURPOSE

Intracerebral vascular malformations including cavernous angiomas (CAs) and arteriovenous malformations (AVMs) are an important cause of chronic pharmacoresistant epilepsies. Little is known about the pathogenetic basis of epilepsy in patients with vascular malformations. Intracerebral deposits of iron-containing blood products have been generally regarded as responsible for the strong epileptogenic potential of CAs. Here, we have analyzed whether blood-brain barrier (BBB) dysfunction and subsequent astrocytic albumin uptake, recently described as critical trigger of focal epilepsy, represent pathogenetic factors in vascular lesion-associated epileptogenesis.

METHODS

We examined the correlation between hemosiderin deposits, albumin accumulation, and several clinical characteristics in a series of 80 drug-refractory epilepsy patients with CAs or AVMs who underwent surgical resection. Analysis of clinical parameters included gender, age of seizure onset, epilepsy frequency, duration of epilepsy before surgery, and postoperative seizure outcome classification according to Engel class scale. Hemosiderin deposits in the adjacent brain tissue of the vascular lesion were semiquantitatively analyzed. Fluorescent double-immunohistochemistry using GFAP/albumin costaining was performed to study albumin extravasation.

KEY FINDINGS

Our results suggest that a shorter duration of preoperative epilepsy is correlated with significantly better postsurgical outcome (p < 0.05), whereas no additional clinical or neuropathologic parameter correlated significantly with the postsurgical seizure situation. Intriguingly, we observed strong albumin immunoreactivity within the vascular lesion and in perilesional astrocytes (57.65 ± 4.05%), but not in different control groups.

SIGNIFICANCE

Our present data on albumin uptake in brain tissue adjacent to AVMs and CAs suggests BBB dysfunction and accumulation of albumin within astrocytes as a new pathologic feature potentially associated with the epileptogenic mechanism for vascular lesions and provides novel therapy perspectives for antiepileptogenesis in affected patients.

Seizures after Onyx embolization for the treatment of cerebral arteriovenous malformation

Onyx embolization of cerebral arteriovenous malformations (AVM) has become increasingly common. We explored the risk of seizures after Onyx use.A retrospective review was conducted of 20 patients with supratentorial brain arteriovenous malformation (AVM) who received Onyx embolization between 2006 and 2009. Baseline demographics, clinical history, seizure history, AVM characteristics and treatment were compared between those who developed post-onyx seizure and those who did not. MRIs were reviewed for edema following Onyx treatment.Of 20 patients who underwent Onyx embolization, the initial AVM presentation was hemorrhage in 40% (N=8). The median number of embolizations was two (range 1-4) and the median final obliteration amount was 90% (range 50-100%). A history of seizure was present in 50% (N=10) of patients pre-embolization and 12 (60%) patients received seizure medications (treatment or prophylaxis) prior to embolization. Seizur post-Onyx embolization occurred in 45% (N=9). The median time to seizur post-Onyx was seven days (range 0.3-210). Four patients (20%) with seizures post-Onyx had no seizure history. Two of these patients (10%) had no other identifiable cause for seizure other than recent Onyx embolization. Seizures in these two patients occurred within 24 hours of Onyx administration. Among patients with post-Onyx seizures, there was a trend toward larger AVM size (P=0.091) and lower percent obliteration (P=0.062). Peri-AVM edema was present in 75% of MRIs performed within one month of Onyx treatment and may represent a possible etiology for seizures.New onset seizures post-Onyx embolization are not uncommon. Further study of seizure prevention is warranted.

Cerebral cavernous malformations and intractable epilepsy: the limited usefulness of current literature

BACKGROUND

Cerebral cavernous malformations (CCM) are known to be highly epileptogenic lesions. A number of studies on CCM surgery deal with CCM-associated seizures and/or epilepsy. In order to counsel patients with CCM-associated epilepsy, clear results from such studies would be highly useful. This study reviews the current literature with the aim to assess its usefulness for presurgical decision-making with emphasis on differentiating outcomes in different epilepsy types.

METHODS

A systematic Medline search identified 27 studies between 1991 and 2009 through the keywords "cavernomas, cavernous, hemangioma, AND epilepsy, AND surgery". They were analysed with regard to clarity of definition of epilepsy subtypes, precision of definition of drug-resistant epilepsy, information on surgical procedure and presurgical workup, seizure outcome and length of follow-up.

RESULTS

Twenty studies included only surgically treated patients. Three types of epilepsy were defined: drug-resistant epilepsy, epilepsy or single/sporadic seizures. In 12 of 27 studies, at least one of these categories remained unclear. The classic definition of drug-resistant epilepsy was not used in the vast majority of studies, with many groups using their own definition. In 30%, the surgical procedure was not described precisely, although 52% of studies used a differentiated preoperative evaluation. Seizure outcome was described using a widely accepted classification in only 48% of series, and in over half of the studies outcome results contained cases with insufficient length of follow-up.

CONCLUSIONS

A large proportion of recent studies on surgery for CCM-associated epilepsy are not using criteria and definitions for the classification of epilepsy and outcome that are commonly used by epileptologists or epilepsy surgeons. This results in the limited usefulness of a large part of the literature for the purpose of preoperative counselling a patient with CCM-associated epilepsy.

Epileptogenicity of Cavernomas Depends on (Archi-) Cortical Localization

BACKGROUND:

Patients with cerebral cavernomas have an estimated risk of the development of epilepsy of 1.5% to 2.4% per patient-year.

OBJECTIVE:

To clarify the predictive value of different risk factors for epilepsy in patients with supratentorial cavernomas.

METHODS:

We retrospectively analyzed data of 109 patients with supratentorial cavernomas. The correlation of epilepsy with the variables of single or multiple cavernomas, sex, age, side, cortical involvement, mesiotemporal archicortical vs neocortical involvement, lobar location of neocortical cavernomas, the presence of a hemosiderin rim and of edema, and the maximal diameters of cavernoma, hemosiderin rim, and edema, if present, were calculated using univariate and multivariate penalized likelihood logistic regression models.

RESULTS:

Cortical involvement was the most relevant risk factor for epilepsy (P &lt; .0001). No patient with a subcortical cavernoma presented with epilepsy. Epilepsy was more common in patients with mesiotemporal archicortical cavernomas than in patients with neocortical cavernomas (P = .02), whereas the lobar location of neocortical cavernomas was not significantly associated with the risk of the development of epilepsy. In the multivariate analysis, a greater diameter of the cavernoma, the absence of edema, and localization in the left hemisphere were also associated with the occurrence of epilepsy (P &lt; .05).

CONCLUSION:

The epileptogenicity of supratentorial cavernomas depends on cortical, especially mesiotemporal archicortical, involvement. Exclusively subcortical cavernomas are highly unlikely to cause epilepsy. This information is helpful in counseling patients with cavernomas regarding their risk of epileptic seizures and in patients with multiple cavernomas and epilepsy to generate a valid hypothesis of which cavernoma may cause epilepsy.

Brainstem cavernous malformations: a review with two case reports

Central nervous system (CNS) cavernous malformations (CMs) are developmental malformations of the vascular bed with a highly variable clinical course due to their dynamic nature. We present one case of 'de novo' brainstem cavernous malformation after radiation therapy adding to the increasing number of reported cases in the medical literature, and the case of a pregnant patient with symptomatic intracranial hemorrhage related to brainstem CMs to illustrate the complex nature in management of these patients, followed by a review of clinical and radiographic characteristics. CMs account for 8-15% of all intracranial and intraspinal vascular malformations. Although traditionally thought to be congenital in origin, CMs may present as acquired lesions particularly after intracranial radiation therapy. Clinical manifestations are protean and surgical treatment should be considered for patients with progressive neurologic deficits.

Magnetic resonance diffusion tensor imaging and tractography of intracranial cavernous malformations: preliminary observations and characterization of the hemosiderin rim

OBJECT

Cavernous malformations (CMs) can cause symptoms that appear out of proportion to the lesion size, leading one to hypothesize that they may have an effect on adjacent white matter that is not fully explained by local mass effect. The goal of this study was to investigate the diffusion tensor (DT) properties of CMs, the hemosiderin rim, and normal-appearing adjacent white matter.

METHODS

Eighteen cavernous malformations were characterized using standard MR imaging sequences as well as 6-direction DT imaging with single-shot echo planar-gradient echo imaging at 3 tesla.

RESULTS

Diffusion tensor imaging demonstrated that CMs have a characteristic signature on DT imaging, with low fractional anisotropy (FA) and high mean diffusivity centrally within the lesion. The hemosiderin rim had a high FA value relative to the central lesion or adjacent white matter. Tractography revealed that tracts neatly deviate around CMs. Tracts were typically seen to pass through the hemosiderin rim.

CONCLUSIONS

The hemosiderin rim of CMs was intimately associated with white matter tracts that were deviated by the central lesion. These findings are consistent with histopathological reports that the hemosiderin rim is composed of blood breakdown products deposited in viable white matter.

Long-term seizure control after resection of supratentorial cavernomas: a retrospective single-center study in 53 patients

OBJECTIVE

The goal of this study was to examine the long-term outcomes of 53 epilepsy patients who were surgically treated for supratentorial cavernomas in a single-center study and to assess both the duration of epilepsy and the resection of the hemosiderin rim for their prognostic relevance during extended follow-up.

METHODS

Fifty-three patients underwent microsurgical resection of radiologically diagnosed supratentorial cavernomas. For the outcome analysis, they were divided into 2 groups: Group A (33 patients) with a preoperative duration of epilepsy of less than 2 years, and Group B (20 patients) with a preoperative duration of epilepsy of 2 years or more. The natural history of the cavernomas, localization and size of the lesions, use of antiepileptic drugs, surgery timing, and technique (removal or not of the surrounding gliosis) were evaluated retrospectively. The outcome of epilepsy was based on Engel's classification and the International League Against Epilepsy classification.

RESULTS

After a mean follow-up period of 8.1 years, 45 (84.9%) of the 53 patients were free from disabling seizures (Engel Class I), including 37 patients (69.8%) who were completely free of postoperative seizures (Engel Class IA); 43 patients (81.1%) were categorized as International League Against Epilepsy Class 1. Outcome was statistically significantly improved in the patient subgroup of our study in which patients underwent a resection of the surrounding gliosis after a preoperative duration of epilepsy of less than 2 years (Group A). There was no mortality, and only minor postoperative neurological deficits occurred in 7.5% of patients.

CONCLUSION

In a long-term follow-up period, 84.9% of the patients in the study could be evaluated as Engel Class I. The analysis of outcome showed that patients benefited significantly from early surgery and excision of the hemosiderin rim.

Disrupted cerebellar development in preterm infants is associated with impaired neurodevelopmental outcome

The unfavorable impact of prematurity on the developing cerebellum was recently recognized, but the outcome after impaired cerebellar development as a prematurity-related complication is hitherto not adequately documented. Therefore we compared 31 preterm patients with disrupted cerebellar development to a control group of 31 gender and gestational age matched premature infants with normal cerebellar development. Supratentorial brain injuries during the neonatal period were comparable between the groups. At a minimum age of 24 months motor and mental development was assessed by standardized tests. Disrupted cerebellar development was associated with significantly poorer scores both in the subtests for neuromotor (p < 0.001) and mental development (p < 0.001), respectively. Mixed CP was diagnosed in 48% of affected patients, whereas none of the patients of the control group had mixed CP. Microcephaly and epilepsy were significantly related to disrupted cerebellar development. Preterm patients with disrupted cerebellar development exhibit poorer outcome results in all investigated variables. The role of the cerebellum in neurodevelopment after prematurity seems to be underestimated so far.

Nitric oxide synthase and NMDA receptor expressions in cavernoma tissues with epileptogenesis

OBJECTIVES

To investigate the contribution of nitric oxide (NO) and the glutamate systems to epileptogenicity of cavernoma (CA).

METHODS

Using immunohistochemistry we examined NO synthases (NOS; neuronal, inducible and endothelial) and N-methyl-D-aspartate (NMDA) receptor subunits 1(NR1) and 2A/B (NR2A/B) in tissues, with and without hemosiderin deposits, adjacent to CA resected from temporal (seven patients) and frontal (one patient) lobes.

RESULTS

All isoforms of NOS, especially iNOS expression, was significantly upregulated in company with NR2A/B expression, not only in declining neuronal cells but also in reactive astrocytes in the tissue, with hemosiderin deposits, adjacent to CA and moreover the degree of iNOS expression was significantly correlated with seizure frequency.

CONCLUSIONS

These preliminary results sustain a speculation that excessive NO may generate in the tissue surrounding CA with repeated microhaemorrhaging and seizures. The neuronal loss and reactive glial proliferation induced by iron or NO may play a role in epileptogenesis.

Neuromagnetic Localization of Spike Sources in Perilesional, Contralateral Mirror, and Ipsilateral Remote Areas in Patients with Cavernoma

PURPOSE

To assess neuromagnetic spike localization as an indication for extended lesionectomy of cavernoma.

METHODS

Electroencephalography (EEG) and magnetoencephalography (MEG) was simultaneously recorded in 17 patients (8 men, mean age 29.7 years) with single cavernoma. The location of the equivalent current dipole (ECD) of the interictal spikes was correlated with the lesion shown by magnetic resonance imaging.

RESULTS

Preoperative ECD localization was classified into four types: perilesional, adjacent to the cavernoma only (n = 6); mirror, adjacent to the lesion and at the contralateral homologous site (n = 5); remote, mainly at a remote site in the ipsilateral hemisphere (n = 3); and no spikes (n = 3). The spikes were detected by only MEG in two of five "mirror" and all three "remote" patients. In the mirror group, contralateral spikes were synchronized with the ipsilateral spikes, or also occurred independently. Two "perilesional" and two "mirror" patients became seizure-free and spike-free after extended lesionectomy. In contrast, the other two "mirror" patients had residual seizures and spikes after pure lesionectomy.

CONCLUSION

The detectability of mirror and remote spikes was higher by MEG than by EEG, whereas the detectability of perilesional spikes was similar by MEG and EEG. Therefore, the use of both EEG and MEG will provide the maximum information about spike distribution and propagation. Residual seizures and spikes after pure lesionectomy, but not after extended lesionectomy, in the "mirror" patients suggest the importance of resection of the perilesional irritable zone. Extended resection of the irritable cortex surrounding cavernoma is recommended for better seizure control, particularly in "mirror" patients.

Multiple cerebral cavernous malformations associated with extracranial mesenchymal anomalies

Cerebral cavernous malformations (CCM) are common hamartous dysplasias characterized by abnormally dilated vascular channels. CCM mostly occur sporadically, and multiple occurrence of CCM is highly suggestive of a genetic origin of the disorder. Typical clinical symptoms are seizures, hemorrhages, focal neurological deficits, and headaches. Three genes have so far been described that are responsible for most cases of familial CCM and more than half of the sporadic cases with multiple CCM (CCM1-3). The coincidence of CCM and other vascular anomalies has been described before. The present review discusses the association of CCM with mesenchymal anomalies, with special emphasis on the possible common pathogenetic pathway for CCM and atrial myxomas. An illustrative case is presented in which CCM occurred together with different dysplasias (multiple CCM, liver cavernoma, and cardiac atrial myxoma), which are all thought to arise from abnormal mesenchymal cell differentiation processes.

Prediction of postoperative outcome with special respect to removal of hemosiderin fringe: A study in patients with cavernous haemangiomas associated with symptomatic epilepsy

PURPOSE

In this study 30 patients with symptomatic epilepsy caused by cavernomas were investigated in a postoperative follow up study to assess predictors for postoperative outcome with respect to indications, time and approach of surgery.

METHODS

Thirty patients with cavernomas refractory to medical treatment were scheduled for surgery based on the findings of high-resolution MR imaging and intensive EEG-video monitoring. Postoperative outcome of epilepsy was assessed by follow-up examinations based on the basis of classification by Engel and the International League against epilepsy (ILAE).

RESULTS

The following variables were associated with good postoperative outcome: (1) complete resection of hemosiderin fringe surrounding the cavernoma was correlated to less postoperative seizure frequency versus incomplete resection of the hemosiderin fringe according to the outcome protocol of ILAE. (2) Lower duration of epilepsy at the time of operation was correlated to a better postoperative outcome with a benefit for recovery. (3) Absence of hemorrhage before surgery and unifocal seizure onset was a predictor for a favorable outcome, whereas bilateral or multifocal seizure onset zones showed poorer postoperative outcomes. (4) In patients with dual pathology (hippocampal sclerosis in addition to a cavernoma), lesionectomy plus hippocampectomy as opposed to lesionectomy only, had a better outcome than single lesionectomy.

CONCLUSION

Postoperative outcome in patients with cavernomas should be the topic of further prospective multicenter studies involving a large number of patients. In addition to the ideal operation time and handling of dual pathology the role of extended resection including perilesional hemorrhages should be taken into account.

Seizure Outcome after Resection of Supratentorial Cavernous Malformations: A Study of 168 Patients

PURPOSE

The optimal management of cerebral cavernous malformations (CCMs) with epileptic seizures is still a matter of debate. The aim of our study was to examine seizure outcome in the largest published series of surgically treated patients with epilepsy due to a supratentorial CCM, and to define predictors for good surgical outcome.

METHODS

We retrospectively studied 168 consecutive patients with a single supratentorial CCM and symptomatic epilepsy in a multicenter study. Pre- and postoperative clinical examinations, age at epilepsy onset, age at operation, type of symptoms due to the CCM (seizures, headache, hemorrhage, focal deficits), type and frequency of epileptic seizures, and the localization and size of the CCM were assessed. Seizure outcome was determined in the first, second, and third postoperative years.

RESULTS

The CCM was completely resected in all patients. More than two thirds of the patients were classified as seizure free in the first 3 postoperative years. Predictors for good seizure outcome were age older than 30 years at the time of surgery, mesiotemporal CCM localization, CCM size <1.5 cm, and the absence of secondarily generalized seizures. No mortality occurred in our series, but only mild postoperative neurologic deficits in 12 (7%) patients.

CONCLUSIONS

Considering the natural history of CCMs, the favorable neurologic and seizure outcome, surgical resection of CCMs should be considered in all patients with supratentorial CCMs and concomitant epilepsy, irrespective of the presence or absence of predictors for a favorable seizure outcome.

Metabolic correlates of epileptic spikes in cerebral cavernous angiomas

BACKGROUND

Cerebral cavernous angiomas (CCA) are frequently associated with focal intractable epilepsy. Epileptogenicity is usually attributed to hemosiderin deposits. Combined recording of electroencephalogram (EEG) and functional magnetic resonance imaging (fMRI) is a new method to investigate epileptic discharges.

METHODS

We used EEG-fMRI to identify BOLD responses to interictal spikes in patients with CCA. Responses were analyzed in the lesional and perilesional area, and at distance.

RESULTS

Eight patients were scanned, all with temporal lobe epilepsy and spikes. One patient had bilateral spikes, analyzed separately, and three studies with less than two spikes were excluded. All six studies analyzed showed BOLD responses. No response was found in the lesion itself or immediate periphery, and the raw fMRI signal showed signal loss in lesional and perilesional areas in all patients. Responses were close to the perilesional area in 2/6 studies. All patients showed responses at a distance from the lesions.

CONCLUSIONS

Despite susceptibility artifacts caused by iron deposits, we demonstrated EEG-fMRI responses involving the perilesional areas in 33% of studies. We also demonstrated diffuse rather than focal responses, in accordance with previous studies in lesional and non-lesional temporal lobe epilepsy, confirming the frequent distant effect of epileptic spikes.

Cerebral cavernous malformations and epilepsy

✓Seizures and epilepsy are frequent clinical manifestations of cerebral cavernous malformations (CCMs) and represent the most common symptomatic presentation of supratentorial lesions. Clinicians often diagnose CCMs in patients after a first seizure, or in some cases after obtaining neuroimaging studies in patients suffering from chronic epilepsy previously thought to be idiopathic. In some cases, the lesion is clinically significant solely because of its epileptogenicity, but in others there may be concern about potential hemorrhage or focal neurological deficits from a similar lesion.

The authors present current pathophysiological concepts related to epilepsy associated with CCMs. They discuss the spectrum of seizure disorders associated with these lesions and review the natural history, prognosis, and options for therapeutic intervention.

Seizure Outcome after Resection of Cavernous Malformations Is Better When Surrounding Hemosiderin-stained Brain Also Is Removed

PURPOSE

Considering the epileptogenic effect of cavernoma-surrounding hemosiderin, assumptions are made that resection only of the cavernoma itself may not be sufficient as treatment of symptomatic epilepsy in patients with cavernous malformations. The purpose of this study was to test the hypothesis whether seizure outcome after removal of cavernous malformations may be related to the extent of resection of surrounding hemosiderin-stained brain tissue.

METHODS

In this retrospective study, 31 consecutive patients with pharmacotherapy-refractory epilepsy due to a cavernous malformation were included. In all patients, cavernomas were resected, and all patients underwent pre- and postoperative magnetic resonance imaging (MRI). We grouped patients according to MRI findings (hemosiderin completely removed versus not/partially removed) and compared seizure outcome (as assessed by the Engel Outcome Classification score) between the two groups.

RESULTS

Three years after resection of cavernomas, patients in whom hemosiderin-stained brain tissue had been removed completely had a better chance for a favorable long-term seizure outcome compared with those with detectable postoperative hemosiderin (p=0.037).

CONCLUSIONS

Our study suggests that complete removal of cavernoma-surrounding hemosiderin-stained brain tissue may improve epileptic outcome after resection of cavernous malformations.

Epileptogenicity of Supratentorial Medullary Venous Malformation

PURPOSE

The purpose of this study was to evaluate the epileptogenicity of supratentorial medullary venous malformation (MVM). Special consideration was given to any associations with intracerebral hemorrhage with or without other vascular malformations, including cavernous angioma (CA).

METHODS

In total, 10 patients with angiographically or histologically verified MVMs were examined. The patients were divided into two groups with or without intracerebral hemorrhage, and their clinical, neuroradiologic, and interictal and ictal EEG findings were reviewed retrospectively.

RESULTS

Although three of five patients in the nonhemorrhagic group had epilepsy, no topographic concordance was found between the MVM location and the EEG focus. On the contrary, in four of five patients in the hemorrhagic group, epilepsy developed, and topographic concordance between the hemorrhagic MVM location and the EEG focus was noted. One patient with a hemorrhagic MVM and an associated CA in the hippocampus had electroclinical pictures of intractable medial temporal lobe epilepsy on this side.

CONCLUSIONS

Although a supratentorial MVM itself is not epileptogenic, the development of an intracerebral hemorrhage may cause epilepsy. In particular, an associated CA may be highly epileptogenic.

Seizure control of Gamma Knife radiosurgery for non-hemorrhagic arteriovenous malformations

OBJECTIVES

Although radiosurgery has been found to be a safe and effective alternative treatment, seizure outcome of arteriovenous malformation (AVM) radiosurgery has not been documented in detail. We report the effect of Gamma Knife radiosurgery (GKRS) on seizures associated with AVMs and discuss the various factors that influence the prognosis.

MATERIAL AND METHODS

Between 1992 and 2004, 246 patients were treated with GKRS for AVMs at Kyung-Hee medical center. Forty five (17.0%) patients have non-hemorrhagic AVMs and presenting symptom was seizure. Two patients of all were excluded from this study due to loss of follow-up after radiosurgery. In this study, retrospective analysis of clinical characteristics, radiologic findings, radiosurgical seizure outcome were performed.

RESULTS

There were 32 male and 11 female with age ranging from 10 to 74 years (mean 35 years). Type of seizure included: general tonic clonic (n = 28); focal motor or sensory (n = 7); partial complex (n = 8). The location of AVM was temporal (n = 18); frontal (n = 9); deep seated (n = 7): parietal (n = 5); occipital (n = 4). Follow-up period was from 8 months to 12 years (mean 46 months). Mean volume was 6.2 cc (2.7-20), mean marginal and maximal dosage was 19.5 (17-26) and 36.6 Gy (13-50). During follow-up after radiosurgical treatment, 23 (53.5%) of 43 patients were seizure-free, 10 (23.3%) had significant improvement, were unchanged in 8 (18.6%) and aggravated in 2 (4.6%) patients. In 33 patients, follow-up angiography or MRI was performed. Complete obliteration was achieved in 16 (49.0%) patients, partial obliteration in 13 (39.0%). Four were unchanged (12.0%). Of 33 patients with follow-up performed, 26 were followed for over 2 years. Eleven (84.6%) of 13 patients with complete obliteration were seizure-free (p < 0.005). Four (36.3%) of 13 with partial obliteration and unchanged remained seizure-free. Fifteen patients had experienced intractable seizure before radiosurgery. After radiosurgery, seizures disappeared in 8 (53%) patients. Seizure frequently decreased in 5 (33%) and 2 patients (14%) were unchanged but none was aggravated. Five (71%) of 7 patients with complete obliteration were seizure-free and 2 (40%) of 5 patients with partial obliteration were seizure-free.

CONCLUSION

Up to now, controversy about resective surgery or radiosurgery as treatment of seizure related to AVMs still remains. In this study, we experienced that Gamma Knife radiosurgery is commonly performed to treat AVMs and can improve symptomatic seizure associated with AVMs. To clarify the mechanism of seizure control in AVMs radiosurgery is difficult, but it seems to be closely related to hemodynamic effects after radiosurgery.

Hirntumoren und Epilepsien

Improved tumor and epilepsy treatment requires long-term care of patients with symptomatic epilepsies caused by tumors. Pathophysiology, epidemiology, prognosis, drugs, and surgical treatment are discussed with special emphasis on seizure control, side effects, and quality of life. Because of the long-term course -- often 10 to 20 years -- optimal treatment strategies have to be selected individually. These should consider possibilities of new techniques of co-registering imaging and electrophysiology, surgery, and the interaction of anticonvulsive and chemotherapeutic drugs, cognition, and mood.

[Cerebral cavernomas, epilepsy and seizures. Natural history and therapeutic strategy]

PURPOSE

To review, from a retrospective series of 48 patients presenting with seizures associated with one or more supratentorial cavernoma(s), the natural history of the seizures and outcome according to medical and surgical treatment.

METHODS

Patients were divided into two groups: group A included patients presenting with a single seizure or rare seizures (n=21), and group B patients having intractable epilepsy (n=27). All received antiepileptic drugs and 35 were operated on (12 in the group A and 23 in the group B). Stereo-EEG was performed in 8 patients in group B. Surgery included lesionectomy alone (n=16), resection of the cavernoma and perilesional tissue (n=7) or tailored corticectomy including the cavernoma (n=12).

RESULTS

The natural history of seizures was different in the two groups: mean age at seizure onset was 25 years in group B and 33 years in group A (p<0.05), seizures were partial in all patients in group B and 8 patients in group A (p<0.05). Seizure frequency and periodicity also varied. Prolonged seizure-free periods were observed. The cavernoma was temporal in 17 patients in group B and 4 patients in group A (p<0.01). In group A, seizure outcome was favorable following surgery or with antiepileptic medication only (7 patients out of 12 operated were seizure-free, as were 5 out of 7 non-operated). In group B, seizure outcome was better after surgery than with medication only (17 patients out of 23 operated were in Engel's Class I, while 3 patients of 4 non-operated patients had persisting seizures despite antiepileptic polytherapy).

CONCLUSION

Variations in seizure severity in patients harboring cavernomas suggest different therapeutic approaches. In case of unique or rare seizures, surgical resection of the cavernoma is appropriate, but benefits of surgery over antiepileptic medication in terms of seizure control remains unclear. Intractable epilepsy associated with cavernomas is better controlled after surgery rather than with medication only. In these patients, a detailed preoperative work-up is necessary and should be followed by wide resection associated or not with corticectomy, especially in the temporal lobe. Evaluation of outcome after surgery should consider the surgical strategy, antiepileptic medications and the patient's seizure history.

Intracranial cavernous angioma: a practical review of clinical and biological aspects

BACKGROUND

Cavernomas are an uncommon lesion seen in neurosurgical practice that can occasionally rupture. Recent developments in neurosurgical technique and microbiology have brought greater insight into the treatment and molecular pathogenesis of cavernoma. In this review, a historical overview of cavernous angioma, a current paradigm for treatment, promising new molecular biological developments, and suggestions for future directions in neurosurgical research are presented, with emphasis on practical clinical applications.

METHODS

A survey of the literature on cavernous angioma and consultation with the Department of Neurosurgery at Northwestern Memorial Hospital was conducted by the authors to gain greater insight regarding this lesion. Papers and consultation revealed the importance of careful evaluation of this lesion, new techniques such as functional magnetic resonance imaging and frameless stereotaxy that simplify clinical management of cavernomas, and potential mechanisms by which to tackle this lesion in the future. New basic knowledge on disease biology is summarized with practical applications in the clinical arena.

RESULTS

There appear to be a number of controversies regarding management of this lesion. These include risk factors faced by the patient, controversy over the importance of resection, and modality through which the treatment should occur. An algorithm is presented to aid the neurosurgeon in management of these lesions.

CONCLUSIONS

Exciting developments in neurosurgery and molecular biology will continue to have a major impact on clinical treatment of this disease. Unresolved issues regarding the importance of certain risk factors, the role for radiotherapy in treatments, and the underlying molecular abnormalities must be tackled to gain greater clarity in treatment of this lesion.

Management of supratentorial cavernous malformations: craniotomy versus gammaknife radiosurgery

OBJECTIVE

Although craniotomy is the preferred treatment for symptomatic solitary supratentorial cavernous malformation (CM), radiosurgery is also an option. Our aim was to see which of these strategies was the most effective and under what circumstances.

METHODS

Of the 46 patients with solitary supratentorial CM that we retrospectively studied, 24 presented with seizures, 16 with focal neurological deficits due to intracerebral hemorrhage, and 6 with both seizures and bleeding. Sixteen were treated with craniotomy and 30 with gammaknife radiosurgery (GKRS). The main outcome measures for comparing craniotomy with GKRS were the proportion of postoperative seizure-free patients and the proportion of patients in whom no rebleeding occurred.

RESULTS

Of patients presenting with seizures with/without bleeding, a significantly higher proportion of the craniotomy group than the GKRS group became and remained seizure-free (11/14 [79%] versus 4/16 [25%]; P < 0.002), and of those presenting with bleeding with/without seizures, a somewhat (though nonsignificantly) higher proportion did not rebleed (4/4 [100%] versus 12/18 [67%]) after surgery. The remaining 2 of the 16 craniotomy patients did not rebleed and had no residual tumor at follow up. Twelve of the 30 GKRS patients had evidence of tumor regression at follow up.

CONCLUSION

In the clinical management of solitary supratentorial CM, craniotomy for lesionectomy resulted in better seizure control and rebleeding avoidance than GKRS.

Gamma knife surgery for cavernous hemangiomas: an analysis of 125 patients

Object. The authors sought to determine the value of gamma knife surgery (GKS) in the treatment of cavernous hemangiomas (CHs).

Methods. Between 1993 and 2002, a total of 125 patients with symptomatic CHs were treated with GKS. Ninety-seven patients presented with bleeding and 45 of these had at least two bleeding episodes. Thirteen patients presented with seizures combined with hemorrhage, and 15 patients presented with seizures alone. The mean margin dose of radiation was 12.1 Gy and the mean follow-up time was 5.4 years.

In the 112 patients who had bled the number of rebleeds after GKS was 32. These rebleeds were defined both clinically and based on magnetic resonance imaging for an annual rebleeding rate of 32 episodes/492 patient-years or 6.5%. Twenty-three of the 32 rebleeding episodes occurred within 2 years after GKS. Nine episodes occurred after 2 years; thus, the annual rebleeding rate after GKS was 10.3% for the first 2 years and 3.3% thereafter (p = 0.0038). In the 45 patients with at least two bleeding episodes before GKS, the rebleeding rate dropped from 29.2% (55 episodes/188 patient-years) before treatment to 5% (10 episodes/197 patient-years) after treatment (p < 0.0001). Among the 28 patients who presented with seizures, 15 (53%) had good outcomes (Engel Grades I and II). In this study of 125 patients, symptomatic radiation-induced complications developed in only three patients.

Conclusions. Gamma knife surgery can effectively reduce the rebleeding rate after the first symptomatic hemorrhage in patients with CH. In addition, GKS may be useful in reducing the severity of seizures in patients with CH.

[Supratentorial cavernoma and epileptic seizures. Are there predictors for postoperative seizure control?]

For cavernous haemangiomas, it is the aim of surgical treatment to control epilepsy and eliminate potential sources of intracerebral haematomas. In the following investigation, it was attempted to find indicators for seizure freedom after surgery. Success of therapy was assessed according to three patterns of classification. Thirty patients underwent tailored resection based on findings from preoperative investigations and intraoperative electrocorticography. Follow-up averaged 4 years. Lesionectomy, extended lesionectomy, and modified lobe resection were carried out in 13, 11, and six patients, respectively. For all procedures, including microsurgical lesionectomy, the firm gliotic layer unequivocally differed in colour and consistency from normal brain and was removed. Further tissue resection was carried out only if the electrocortical course suggested persistent spike activity around the resection cavity or if presurgical MRI evaluation (e.g. hippocampal atrophy) or electrophysiology also pointed to pathology distant from the lesion. Of the patients, 53.3% became completely seizure-free (Engel I), and one additional patient had only occasional isolated auras. Dramatic reductions in seizure frequency and severity were exhibited by 26.7%. Outcome in respect to seizure control was not associated with resection procedure, comparing pure lesionectomy with lesionectomy plus cortectomy. In the group of patients with epilepsy surgery, those with hippocampectomy had significantly better outcome than those without. Important prognostic factors were early operation after seizure manifestation (91.7% operated upon within 2 years of seizure onset became seizure-free). Another prognostic factor was unifocal seizure onset (bilateral or multifocal seizure onset was found in care of the ten patients with unfavourable outcome). None of the four patients harbouring multiple cavernomas became seizure-free after resection of one lesion, which was believed to be mostly attributable to the epileptic focus that was removed.

Cavernous haemangiomas, epilepsy and treatment strategies

BACKGROUND

Cavernous haemangiomas (cavernomas) are benign vascular malformations which can be found at any region within the central nervous system. Epilepsy is the most frequent manifestation of this malformation. Magnetic resonance imaging (MRI) used for the diagnostic evaluation of symptomatic seizures is a sensitive and specific method for the detection of cavernomas. Due to an increased application of MR imaging in the diagnostic evaluation of symptomatic seizures cavernomas have been found with increasing frequency over the past years. To achieve optimal treatment of patients with cavernous haemangiomas and epilepsy both medical and surgical treatment have to be considered.

OBJECTIVE

This paper reviews published studies and presents our own results concerning current treatment schedules of epileptogenic cavernomas.

RESULTS

In patients with intractable epilpesies surgical treatment of cavernomas seems to be the most successful antiepileptic therapy. Whether microsurgical lesionectomy, including the removal of only the cavernoma, or a more extensive resection is needed to achieve this aim are discussed.

CONCLUSION

New data acquired with high-resolution imaging (MRI, PET) and electrophysiology indicate that magnetencephalography (MEG) may contribute to the delineation of epileptogenic tissue bordering the lesion, thus permitting appropriate inclusion of this specific area within the resection, instead of performing a simple lesionectomy.

Aetiology of epilepsy in surgically treated patients in China

The aim of this retrospective, multicenter clinical study was to evaluate the aetiology of epilepsy in surgically treated patients in China. The detailed clinical records of all intractable partial epilepsy (IPE) were reviewed in five tertiary referral centres from June 1991 to June 2000. 1650 patients (927 males, 723 females) were recruited. 41.4% had aetiological factors, including the histories of major brain trauma (20.9%), febrile seizure (6.5%), meningitis (5.4%), encephalitis (5.0%), prenatal distress (2.1%), birth trauma (0.8%) and family history of seizure (0.7%). The pathological lesions were divided into eight groups according to the nature of the lesion: scar (19.2%), vascular malformations (VM) (17.7%), hippocampal sclerosis (HS) (16.2%), tumours (15.0%), gliosis (12.1%), neuronal migration disorders (NMDs) (7.4%), intracranial infection (4.5%), and other lesions (7.9%). In conclusion, effective management of these aetiological factors and pathological lesions may be essential to deal with IPE. Scar, HS, VM, NMDs are the most likely consequences of antecedent morbid events.

Implementation of T2*-weighted MR for multimodal image guidance in cerebral cavernomas

The aim of this study was to evaluate the feasibility, the safety, and the usefulness of T2*-weighted magnetic resonance (MR) for neuronavigational guidance in patients with cerebral cavernomas. Eight patients with intracerebral cavernomas were operated assisted by T2*-weighted MR image-guidance. The cavernomas were either deep-seated or in eloquent regions. Image fusion of a contrast-enhanced T1-weighted gradient-echo (GRE) sequence with a T2*-weighted GRE sequence was performed via an automated fusion software (StealthMerge). The T2*-weighted images were used to secure complete resection of the cavernoma in all patients and to verify resection of surrounding hemosiderin-stained tissue in epilepsy cases. Furthermore, the multimodal neuronavigational concept included ultrasonography, corticography, and evoked potentials. Postoperative MR excluded any residual malformation in all cases. There was no postoperative morbidity; all epilepsy patients are seizure-free up to now. In our preliminary series, T2*-GRE-guided neuronavigation proved useful for resection control in cavernoma surgery, and we suppose that it will be helpful to clarify the discussion on the value of resection of the surrounding hemosiderin-stained tissue.

Arteriovenous malformations: assessment of gliotic and ischemic changes with fluid-attenuated inversion-recovery MRI

RATIONALE AND OBJECTIVES

To evaluate the diagnostic potential of fluid-attenuated inversion-recovery (FLAIR) MRI in the assessment of patients with cerebral arteriovenous malformations (AVMs) and to correlate the MR findings with clinical symptoms, in particular, perilesional gliosis and ischemic changes.

METHODS

Forty-five patients with cerebral AVMs were examined with FLAIR and conventional T1- and T2-weighted MRI by using identical slice parameters. Images were assessed in a two-reader study for detection and delineation of gliotic and ischemic tissue. Also, the extent of the flow void phenomenon and image artifacts were evaluated.

RESULTS

FLAIR MRI was rated superior to the conventional T2-weighted fast spin-echo imaging in the assessment of intralesional and perilesional gliosis. The superior delineation was a result of the suppression of cerebrospinal fluid, mild T1 weighting, and the more pronounced flow void phenomenon. There was no significant correlation between the extent of gliosis and the clinical symptoms. However, larger AVMs had more extensive signal changes.

CONCLUSIONS

FLAIR is a valuable MRI technique to assess gliotic and ischemic changes in or close to cerebral AVMs. Because gliotic and ischemic changes are common findings and are known to be associated with epilepsy, in the assessment of these patients FLAIR is clinically useful and may guide decisions about treatment-for instance, the extent of surgical resection of the potential epileptogenic focus.

Temporal lobe epilepsy: when are invasive recordings needed?

Temporal lobe epilepsy (TLE) is the most common type of medically intractable partial epilepsy amenable to surgery. In the majority of cases, the underlying pathology in temporal lobe epilepsy is mesial temporal sclerosis (MTS). Whereas historically invasive recordings were required for most epilepsy surgeries, indications have dramatically changed since the introduction of high-resolution MRI, which uncovers structural lesions in a high percentage of cases. No invasive recordings are required to perform a temporal lobectomy in patients with intractable epilepsy who have structural imaging suggesting unilateral MTS and concordant interictal and ictal surface EEG recordings, functional imaging, and clinical findings. Invasive testing is needed if there is evidence of bitemporal MTS on structural imaging and/or electrophysiologically, and additional information from functional imaging, neuropsychology, and the intracarotid amobarbital (Wada) test also does not help to lateralize the epileptogenic zone. Depth electrodes can be particularly helpful in this setting. However, no surgery is indicated, even without invasive recordings, if bitemporal-independent seizures are recorded by surface EEG and all additional testing is inconclusive. Other etiologies of TLE such as a tumor, vascular malformation, encephalomalacia, or congenital developmental abnormality account for about 30% of all patients who undergo epilepsy surgery. Epilepsy surgery is indicated after limited electrophysiologic investigations if neuroimaging and electrophysiology converge. However, approaches for resection in lesional temporal lobe epilepsy vary among centers. Completeness of resection is crucial and invasive recordings may be needed to guide the resection by mapping eloquent cortex and/or to determine the extent of the non-MRI-visible epileptogenic area. Specific approaches for the different pathologies are discussed because there is evidence that the relationship between the lesions visible on MRI and the epileptogenic zone varies among lesions of different pathologies, and therefore variable surgical strategies must be applied.

Surgical treatment for intractable epilepsy caused by cavernous angioma in the temporal lobe of the dominant hemisphere--three case reports

The surgical treatment modality for intractable epilepsy with cavernous angioma in the dominant hemisphere is still unclear. Three patients with medically intractable seizures associated with cavernous angioma in the dominant hemispheric temporal lobe underwent tailored resection based on magnetic resonance (MR) imaging, single photon emission computed tomography (SPECT), electroencephalography monitoring (from scalp and sphenoidal electrodes), and neuropsychologic assessment. Epileptogenic zones were located in the area surrounding the angioma in all patients and mesial temporal dysfunction in two patients. The adjacent cortex and gliotic tissues containing hemosiderin were resected, in conjunction with either total or partial resection of the nidus. Intraoperative electrocorticography (ECoG) was then performed. Additional resection of the mesial temporal structures or multiple subpial transection was performed as indicated by the ECoG findings. All three patients have been seizure free and showed no language or cognitive deterioration for 30, 18, and 14 postoperative months, respectively, while receiving tapered antiepileptic medication. Tailored resection based on electrophysiological data, MR imaging, SPECT, and intraoperative ECoG is effective for the treatment of medically intractable seizure associated with cavernous angioma in the temporal lobe of the dominant hemisphere.

Source localization and possible causes of interictal epileptic activity in tumor-associated epilepsy

Electrophysiological studies in gliomas have demonstrated action potentials in neoplastic cells. These "spiking tumor cells" are, however, an enigma. In attempt to find evidences for spikes within tumoral borders, 21 patients with different intracerebral tumors were preoperatively screened for the occurrence of epileptogenic discharges using multichannel MEG and EEG. A correlation between histopathology and the distance between dipole and tumor border could be found. Glioma patients showed epileptic activities closer to the border than those with mixed glioneuronal neoplasms and metastases. Four glioma patients demonstrated epileptic activity within the tumor boundary, however, not in the deep center of the tumor. Patch-clamping of cells from acute glioma slices did not yield a correlation between the presence of voltage-gated sodium channels in tumor cells and the MEG/EEG data. Our results demonstrate that the zone with the highest epileptogenic potential is different in gliomas and other brain tumors. However, our data do not strongly suggest that glioma cells are directly involved in the generation of tumor-associated epilepsy in vivo via their capability to generate action potentials.

Postoperative seizure outcome in a series of 114 patients with supratentorial arteriovenous malformations

The incidence of de novo and ongoing postoperative seizures and factors implicated in an increased likelihood of seizures following supratentorial cerebral arteriovenous malformation (AVM) resection remain controversial. We investigated the frequency, severity and variables associated with postoperative seizures in 114 consecutive patients who underwent complete surgical excision of supratentorial AVMs at our institution. The minimal follow up period was 24 months. The incidence of seizures post-AVM surgery was 21% (less than half that found preoperatively). The incidence of postoperative seizures first manifesting >12 months post-AVM resection was 6.3%. A history of preoperative seizures was associated with an increased likelihood of multiple (> or =4) seizures >1 month post-AVM resection (chi2 = 4.38, P = 0.04). Poor functional neurological outcome at 12 months was also a risk factor for the development of > or =1 postoperative seizure using logistic regression analysis (P = 0.04, odds ratio 1.52, 95% CI 1.01-2.28). Cessation of AED therapy in all patients who remain seizure-free at 12 months post-AVM resection is appropriate due to a low risk of new seizure onset or seizure recurrence.

Antiepileptic effects of allopurinol on EL mice are associated with changes in SOD isoenzyme activities

We have investigated the potential antiepileptic action of superoxide dismutase (SOD) activities in the brain of the epileptic mutant EL mouse. EL mice which experienced frequent seizures (EL[s]) had abnormally low levels of SOD isoenzyme activity in the hippocampal area. Once epileptogenicity was established in these animals, activity of cyanide-sensitive Cu,Zn-SOD was maintained at significantly lower levels than in control mice. However, cyanide-insensitive Mn-SOD activity was not different from non-epileptic controls. In EL mice which had not experienced seizure provoking stimulations and exhibited no seizures (EL[ns]) there was moderately lower levels of SOD isoenzyme activities compared to controls. In spite of the low level of Cu,Zn-SOD activity in EL[s] mice, the Cu,Zn-SOD protein content was high in the hippocampus of these animals, suggesting that inactive Cu,Zn-SOD might be induced during development. After allopurinol (ALP) was given orally to EL[s] mice, Cu,Zn-SOD activities increased dramatically in the hippocampus and seizure activity was decreased. Even after 48 h, when antiepileptic action of ALP was lost, the SOD activity was maintained at the high level associated with initial ALP administration. EL[s] mice also showed DNA fragmentation in the hippocampal CA1 region and the parietal cortex, detected with in situ terminal transferase-mediated dUTP nick labeling with the aid of alkaliphosphatase or peroxidase. The degree of DNA fragmentation was less severe in EL[ns] mice. We propose that abnormalities in region specific Cu,Zn-SOD isoenzyme activity might produce free radicals, leading to DNA fragmentations and cell loss. This might contribute to hippocampal epileptogenesis in EL mice.

Surgical outcome in patients with epilepsy with occult vascular malformations treated with lesionectomy

PURPOSE

This retrospective study reports the long-term surgical outcome of patients with medically refractory epilepsy and vascular malformations who were treated with lesionectomy. A detailed analysis of surgical failures had been performed in an attempt to define predictors of surgical success and failure.

METHODS

Fifteen patients with medically intractable epilepsy and angiographically occult vascular malformations (AOVMs) were treated surgically with lesionectomy at Duke University Medical Center. Lesionectomy consisted of removal of the AOVM and surrounding hemosiderin-stained brain only, without the use of electrocorticography (ECoG) to guide resection.

RESULTS

Eleven (73%) patients are seizure free after lesionectomy. Three showed no significant improvement, and one patient died, presumably after a seizure. Age of onset, duration of seizures, age at resection, and gender did not affect outcome. All patients with neocortical AOVMs in whom EEG findings correlated with the site of the lesion were seizure free after lesional resection. Treatment failures were associated with the presence of multiple intracranial lesions, poorly localized or diffuse EEG findings, discordant positron emission tomography (PET) imaging, or with a lesion in close proximity to the limbic system.

CONCLUSIONS

Lesionectomy, with removal of surrounding hemosiderin-stained brain, can be considered the procedure of choice in carefully selected patients with epilepsy with occult vascular malformations.

Modified approach for the selective treatment of temporal lobe epilepsy: transsylvian-transcisternal mesial en bloc resection

OBJECT

The authors propose a novel surgical approach for amygdalohippocampectomy (AH) in patients with temporal lobe epilepsy. Via a transsylvian-transcisternal route, the parahippocampal gyrus is directly exposed from its medial aspect, thus allowing a standardized en bloc resection of the temporomesial epileptogenic structures--the amygdala, anterior hippocampus, parahippocampal gyrus, and subiculum. Additional anatomical studies have been performed for standardization of this approach.

METHODS

From 1990 to 1996, 32 patients presenting with medically intractable mesial temporal lobe epilepsy underwent AH via the transsylvian-transcisternal approach. Preoperative computerized tomography and magnetic resonance imaging revealed temporomesial lesions in 16 patients. Histopathological examination revealed cavernous malformations in seven patients, low-grade astrocytomas in four, hamartomas in three, and gangliogliomas in two patients. Specimens obtained in patients with no lesions were diagnosed as hippocampal sclerosis in all cases. No patient experienced permanent morbidity. Nine percent of the patients developed a temporary partial oculomotor nerve palsy. Only one patient developed a postoperative visual field deficit with a contralateral quadrantanopsia. With respect to seizure outcome, all patients benefited from surgery. At follow-up evaluation (mean 26.4 months), 80% of the patients were free from seizures (Engel Class I). Eight patients in this group were no longer receiving medication. Seventeen percent had experienced only one to several seizures since surgery (Engel Class II) and 3% reported a worthwhile improvement (Engel Class III).

CONCLUSIONS

In contrast to previously described standard techniques for AH, the transsylvian-transcisternal approach presented in this study offers improved anatomical orientation and intraoperative control over the mesial temporal lobe and preserves the lateral as well as the laterobasal temporal lobe.

Lesionectomy in epileptogenic temporal lobe lesions: preoperative seizure course and postoperative outcome

A series of 54 patients operated on for temporal epileptogenic lesions is reported: 36 had slow growing tumours, 18 supratentorial cavernous angiomas. The patients were divided into two different groups according to the presence of seizures controlled (group 1) or not controlled (group 2) by antiepileptic drugs (AEDs). All the patients underwent preoperative scalp EEG and magnetic resonance imaging (MRI). They were operated on by pure lesionectomy, associated with amygdalo-hippocampectomy in 8 cases of uncontrolled seizures. Postoperatively they underwent MRI examination which revealed an incomplete lesionectomy in 12 cases. Patients were followed up after surgery for at least 2 years, 6 of them were reoperated on for the persistence (or regrowth) of the tumour. The results of epilepsy outcome are reported. These cases underline the importance of preoperative electroclinical study, in order to determine the relationship between lesion location and epileptic focus. If good concordance is present, a complete lesionectomy is enough to cure the patient. In other cases associated amygdalo-hippocampectomy leads to better results, while more complicated cases may need preoperative stereo-EEG studies.

Supratentorial cavernous angiomas and epileptic seizures: preoperative course and postoperative outcome

OBJECTIVE

Patients operated on for supratentorial cavernous angiomas were studied to define the incidence and the course of seizures in their clinical history. Electroclinical and neuroradiological data were correlated with the location of cavernomas. The impact of lesionectomy on the outcome of seizures was evaluated.

METHODS

Preoperative clinical data on the history of the seizures, semeiology, incidence, severity, and response to antiepileptic drugs were analyzed. The location of the cavernomas, revealed by magnetic resonance imaging, was correlated with electroencephalographic and clinical data. Postoperative clinical and neuroradiological data were evaluated, with particular consideration to the outcome of the seizures, antiepileptic drug withdrawal, and the completeness of the lesion excision.

RESULTS

A higher incidence of severe epilepsy was observed in the patients with mesiotemporal and cortical angiomas. In most of the patients (78.7%), a good concordance between the site of the lesion and the electroclinical data was found. The complete removal of the lesion led to a favorable outcome, with discontinuation of antiepileptic drugs achieved in one-quarter of the patients.

CONCLUSION

A high percentage of patients with cortical cavernomas had epileptic seizures. They often presented with chronic intractable epilepsy (44.7% in our series). In cases of good concordance between the electroclinical data and the location of the angioma, complete lesionectomy led to the disappearance of seizures. Removal of the hemosiderin ring did not correlate with better outcome. Preoperative ictal scalp recordings to assess the topographic relationship between the cavernoma and the epileptic seizures could improve outcome, which suggests different surgical strategies (lesionectomy versus enlarged resection) in patients without a clear-cut concordance between the site of the lesion and the ictal semeiology.