Factors of surgical outcome in tumoural epilepsy

Frontal lobe low-grade tumors seizure outcome: a pooled analysis of clinical predictors

OBJECTIVE

Seizures present in 50-90 % of cases with low-grade brain tumors. Frontal lobe epilepsy is associated with dismal seizure outcomes compared to temporal lobe epilepsy. Our objective is to conduct a systematic review, report our case series, and perform a pooled analysis of clinical predictors of seizure outcomes in frontal lobe low-grade brain tumors.

METHODS

Searches of five electronic databases from January 1990 to June 2022 were reviewed following PRISMA guidelines. Individual patient data was extracted from 22 articles that fit the inclusion criteria. A single-surgeon case series from our institution was also retrospectively reviewed and analyzed through a pooled cohort of 127 surgically treated patients with frontal lobe low-grade brain tumors.

RESULTS

The mean age at surgery was 30.8 years, with 50.4 % of patients diagnosed as oligodendrogliomas. The majority of patients (81.1 %) were seizure-free after surgery (Engel I). On the multivariate analysis, gross total resection (GTR) (OR = 8.77, 95 % CI: 1.99-47.91, p = 0.006) and awake resection (OR = 9.94, 95 % CI: 1.93-87.81, p = 0.015) were associated with seizure-free outcome. A Kaplan-Meier curve showed that the probability of seizure freedom fell to 92.6 % at 3 months, and to 85.5 % at 27.3 months after surgery.

CONCLUSION

Epilepsy from tumor origin demands a balance between oncological management and epilepsy cure. Our pooled analysis suggests that GTR and awake resections are positive predictive factors for an Engel I at more than 6 months follow-up. To validate these findings, a longer-term follow-up and larger cohorts are needed.

Seizures in patients with low-grade gliomas--incidence, pathogenesis, surgical management, and pharmacotherapy

Seizures complicate the clinical course of > 80% of patients with low-grade gliomas. Patients with some tumor variants almost always have epilepsy. Diffuse low-grade gliomas (LGG) are believed to cause epilepsy through partial deafferentiation of nearby brain cortex (denervation hypersensitivity). Glioneural tumors may interfere with local neurotransmitter levels and are sometimes associated with structural abnormalities of the brain which may produce seizures. The severity of tumor associated epilepsy varies considerably between patients. Some cases may present with a first seizure. Others suffer from long-standing pharmacoresistant epilepsy. Seizure control rates of > 70-80% can be expected after complete tumor resections. Patients with drug-resistant epilepsy require a comprehensive preoperative epileptological work-up which may include the placement of subdural (and intraparenchymal) electrodes or intraoperative electrocorticography (ECoG) for the delineation of extratumoral seizure foci. Partial and subtotal tumor resections are helpful in selected cases, i.e. for gliomas involving the insula. In one series, 40% of patients presented for surgery with uncontrolled seizures, i.e. medical therapy alone often fails to control tumor-related epilepsy. Use of the newer (second generation) non-enzyme inducing antiepileptic drugs (non-EIAED) is encouraged since they seem to have lesser interactions with other medications (e.g. chemotherapy). Chemotherapy and irradiation may have some minor beneficial effects on the patients' seizure disorder. Overall 60-70% of patients may experience recurrent epilepsy during long-term follow-up. Recurrent seizures (not infrequently heralding tumor recurrence) after surgery continue to pose significant clinical problems.

Presurgical seizure frequency and tumoral etiology predict the outcome after extratemporal epilepsy surgery

OBJECTIVE

To examine the predictive value of demographic data for the seizure outcome after extratemporal epilepsy surgery.

METHODS

Eightyone patients who underwent resective extratemporal epilepsy surgery were retrospectively studied concerning (a) age at surgery, (b) onset of epilepsy, (c) duration of epilepsy, (d) number of seizures at the time of presurgical evaluation, (d) number of presurgically tested antiepileptic substances and (f) number of seizure types. The data were correlated to the postoperative seizure outcome after two years.

RESULTS

33 patients (40.7%) were seizure free two years after surgery. Univariate and multivariate analysis revealed that both tumor etiology and low presurgical seizure frequency were independently associated with seizure freedom after epilepsy surgery. The recurrence rate in patients with one or more seizures per day was more than two-fold if compared with patients with fewer seizures. The remaining demographic factors did not show a significant association with seizure outcome in our 81 patients.

CONCLUSIONS

Fewer than daily seizures prior to surgery and a tumoral etiology independently increase the likelihood of remaining seizure free two years after extratemporal epilepsy surgery.

Lesionectomy in epileptogenic gangliogliomas: seizure outcome and surgical results

We retrospectively analysed seizure outcome and surgical results in a series of 21 patients with ganglioglioma treated with lesionectomy. The 21 patients (13 males, eight females) had a history of epilepsy longer than 1 year and post-operative follow up of at least 1 year. Information on the duration of the seizures, type and frequency was retrieved from medical records. In all patients, surgery was limited to the tumour. The interval between onset of seizures and surgery ranged from 1 to 35 years (mean 11). Patient age ranged from 6 to 61 years (mean 27.5). Fifteen patients (71.4%) had complex partial seizures and six had simple partial seizures. Secondary generalisation was present in 10 patients (47.6%). Seizure frequency varied from several per day to one per month. Sixteen tumours were temporal (76.1%; 11 temporo-mesial, five temporo-lateral), and five were extratemporal (23.8%). The mean follow-up period was 5.4 years (range: 1.25-10 years). No tumour progression was observed. No patient died during surgery or the post-operative course. Fourteen patients (66.6%) were Engel class I (five temporo-mesial, five temporo-lateral, four extratemporal) and seven (33.3%) were Engel class II. Post-operative complications were observed in six patients (28.6%), two of whom had cerebellar haemorrhage, possibly due to increased transmural venous pressure. In our patients with temporal neocortical and extratemporal ganglioglioma, lesionectomy allowed good seizure control. The unsatisfactory outcome for mesiotemporal gangliogliomas might indicate the need for extensive neurophysiological presurgical evaluation in order to perform tailored surgery. To avoid cerebellar haemorrhage, attention should be paid to those factors involved in transmural venous pressure increases.

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.

Application of neuronavigator coupled with an operative microscope and electrocorticography in epilepsy surgery

Application of neuronavigator coupled with an operative microscope and electrocorticography (ECoG) is a new trial for epilepsy surgery for achieving better seizure outcome and better efficiency for lesionectomy. We used a neuronavigator coupled with a microscope to delineate the magnetic resonance image-detected lesion for lesionectomy and used ECoG for evaluation of the epileptogenic foci. There were 46 patients with medically intractable partial seizures who underwent craniotomy for epilepsy surgery. Half of the patients had lesions at the temporal lobe and another half at the extratemporal lobe. Sixty-one percent of the patients were seizure-free (grade I) and 22% were nearly seizure-free (grade II). Overall, 83% of the patients had satisfactory seizure control. Complete lesion removal was successful in 37 patients (80%). For lesions with requiring complete removal, neuronavigator coupled with a microscope was 95% effective for lesionectomy. Class A of postresection ECoG had a higher rate of seizure-free outcome (92%) (P < .05). On the other hand, 93% of patients (26/28) with seizure-free outcome (grade I) needed complete lesion resection (P < .05). Lesions at the extratemporal lobe yielded a higher rate of seizure-free outcome (78.2%, 18/23) (P < .05). Application of neuronavigator and ECoG (additional cortical resection) is usually necessary for temporal lobe lesions. All patients with cavernous hemangioma were seizure-free. The complication rate in our study was 8.7%. Neuronavigator coupled with a microscope provides efficacy and safety to complete lesionectomy, which is a key point of seizure outcome. Intraoperative ECoG is valuable for evaluating the epileptogenic foci for epilepsy surgery especially for lesions at the temporal lobe.

[Extra-hippocampal temporal lesions inducing symptomatic drug-resistant epilepsies. Which surgical procedure?]

In partial symptomatic epilepsy due to discrete brain lesion, total removal of the epileptogenic lesion generally yields major reduction of seizures, achieved in 85% of the patients. However, prognosis is worse in patients with symptomatic temporal lobe epilepsy. Implication of the temporo-mesial structures in the seizures genesis is generally considered. Careful electroclinical and radiological analysis can provide useful but insufficient information. In order to evaluate the criteria we used to guide our surgical strategy, we analyzed retrospectively a series of 47 patients with drug-resistant symptomatic extra hipocampic temporal epilepsy surgically treated either by isolated lesionectomy (group 1, n=17) or by resection of temporo-mesial structures and associated lesionectomy (group 2, n=30). Patients with extrahippocampal lesions and hippocampal sclerosis (dual pathology) were excluded from this study. With a mean follow-up of 72 months, overall results showed that 84% of group 2 patients (Engel's grade Ia) were seizure-free compared with only 47% of group 1 patients. Statistical analysis showed that the type of surgical procedure was the main prognostic factor. In conclusion, the optimal surgical procedure cannot be defined only with the criteria usually retained for temporo-mesial involvement in seizure genesis. Taking into account the prognostic value of such implication, although complex, is of paramount importance. Our results could be explained by the presence of an acquired dual functional pathology.

Retrospective analysis of variables favouring good surgical outcome in posterior epilepsies

AIM

to determine variables favouring good surgical outcome in posterior epilepsies.

METHODS

Fourteen patients submitted to epilepsy surgery were included in the study. The epileptogenic zone was located in temporo-parieto-occipital areas as assessed by both invasive and non-invasive pre-surgical evaluation. Several variables (age at first seizure; age at surgery; disease duration; type, frequency and clinical semiology of seizures; presence of lesion; scalp ictal and interictal EEG; localization and extension of epileptogenic zone; completeness of surgical resection) were compared (Fisher's exact test) with freedom from seizures to determine whether surgical outcome (Engel's classification) could be related to any of them.

RESULTS

Seven patients were seizure free (Ia) and very satisfying results were obtained for 3 patients (2 Ib, 1 Ic). New post-surgical visual deficits occurred only in 3 patients. Surgical outcome was related significantly to two variables: scalp ictal EEG (focal versus non-focal; p: 0.014) and completeness of surgical resection of epileptogenic zone (p: 0.0023). A significant trend towards a better outcome for focal interictal intracranial activity versus a non-focal one (p: 0.07) was found.

CONCLUSIONS

The correlation between completeness of epileptogenic zone resection and surgical outcome suggests that a presurgical protocol, allowing a precise definition of the area of resection, could help in obtaining more satisfying results in posterior epilepsies.

Preoperative clinical evaluation, outline of surgical technique and outcome in temporal lobe epilepsy

Temporal lobe epilepsy (TLE) is the most common type of refractory epilepsy. The mechanisms of epileptogenesis and seizure semiology of the mesial and neocortical temporal lobe epilepsy are discussed. The evaluation and selection of patients for TLE surgery requires team work: the different clinical aspects of neuropsychological evaluation, magnetic resonance and functional imaging (positron emission tomography, single photon emission computed tomography and magnetoenephalography) are reviewed. In our programme of epilepsy surgery at Kuopio University Hospital, Finland, we have performed 230 temporal resections from 1988 until 2002. Preoperative diagnostic EEG-videotelemetry often required intracranial monitoring and it has proved to be safe and efficient. The indications and technique for tailored temporal lobe resection with amygdalohippocampectomy used in our institution, as well as the complications, are described. Our analysis of outcome after temporal lobe surgery included 140 consecutive adult patients between 1988 and 1999; one year after the operation in unilateral TLE the Engel I-II outcome was observed in 68% of the patients. Outcome of surgery improved significantly after introduction of the standardised MR imaging protocol from 1993; 74% of patients with unilateral TLE achieved Engel I-II outcome.

Seizure control and cognitive outcome after temporal lobectomy: a comparison of classic Ammon's horn sclerosis, atypical mesial temporal sclerosis, and tumoral pathologies

PURPOSE

Neuropathologic examination of resected tissue after anterior temporal lobectomy (ATL) for treatment of complex partial seizures revealed several distinct histologic substrates. Our study examined the relation between neuropathology, seizure control, and cognition in ATL patients and described preliminary profiles to aid in the prediction of outcome.

METHODS

Of the 149 patients who underwent ATL from 1980 to 1999, long-term follow-up was available for 145. Specimens from 124 of the 145 patients had histologic findings consistent with one of three diagnoses: classic Ammon's horn sclerosis (cAHS; n = 75), atypical mesial sclerosis (Atypical; n = 21), or low-grade tumor (Tumor; n = 28). The other 20 patients had diverse pathologies that were insufficient for analysis. ATL patients underwent a complete preoperative and 68 underwent a postoperative neuropsychological evaluation.

RESULTS

Of the 145 patients, 84% of cAHS, 57% of Tumor, and 29% of Atypical patients had a > or =95% reduction in seizure frequency. Neuropsychological testing suggested that cAHS patients demonstrate more generalized preoperative cognitive impairment than do the Atypical or Tumor patients. The Atypical group recalled significantly less nonverbal material after surgery than did the cAHS or Tumor groups. Stratification by both pathology and surgery side revealed that the right Atypical patients declined more on information processing and set shifting.

CONCLUSIONS

Patients with cAHS or Tumor demonstrated better seizure control and fewer declines in cognitive functioning after ATL than did the Atypical patients, highlighting the need to investigate this group as a distinct entity.

Frontal lobe tumoral epilepsy: clinical, neurophysiologic features and predictors of surgical outcome

PURPOSE

To review the clinical, neurophysiologic features and surgical outcomes in patients with frontal lobe tumors and chronic intractable seizures.

METHODS

Medical records of patients with intractable epilepsy who underwent resection or stereotactic biopsy of frontal lobe tumor (confirmed by surgical pathology) seen between 1985 and 1999 at Yale University School of Medicine Epilepsy Center were reviewed for age at diagnosis, age at onset of seizures, delay between seizure onset and tumor diagnosis, types and frequencies of seizures, EEG results, use of anticonvulsants, extent of surgery, pathological diagnosis, and tumor recurrence.

RESULTS

Thirty-seven patients were included. Mean age at seizure onset was 31.6 years, and at tumor diagnosis was 36.2 years. Mean duration between onset of seizures and tumor diagnosis was 6.1 years. Seventeen patients had auras. Seizure frequency averaged 7.6 seizures per week, with 58% of patients having more than one seizure type. All patients used anticonvulsants, with 90% eventually using polytherapy. All patients eventually underwent at least one surgical procedure. Only 13 (35.1%) patients were class I. Twelve (32.4%) patients were class II, seven (18.9%) class III, and five (13.5%) class IV. No statistically significant differences were seen between good and poor long-term seizure outcome in relation to specific tumor pathology, seizure types, or type of resection.

CONCLUSIONS

Long-term surgical outcomes in tumoral frontal lobe epilepsy are more favorable than those in nontumoral intractable frontal lobe epilepsy (65% class I or II) and less favorable than those in other tumoral epilepsy (overall, 70% class I). Frontal location of intracranial neoplasm may predict a less favorable long-term epilepsy prognosis than tumoral epilepsy in general, an observation for which several explanations are proposed.