Investigation of the effects of Gamma Knife radiosurgery on optic pathways using diffusion tensor MRI within the first year after treatment.

PURPOSE: To investigate the radiation-induced effects of Gamma Knife radiosurgery (GKRS) for sellar-parasellar tumors on optic pathways using DTI parameters within the first year after treatment. METHODS: Twenty-five patients with sellar-parasellar tumors underwent MRI before and 3 months after GKRS, including T1WI, DTI, T2WI. Moreover, 21 patients underwent follow-up DTI 6-8 months after radiosurgery. ROIs were set on optic nerves, optic radiations, and control localizations; DTI parameters for each were calculated. Pre- and post-radiosurgery differences in DTI values were statistically compared and assessed with respect to tumor size changes. RESULTS: Following GKRS, DTI parameters, notably ADC, FA, and RD, showed statistically significant changes in optic nerves and anterior optic radiations. DTI changes were more significant in the group of cases with tumor shrinkage. In this group, DTI of the anterior optic radiations further deteriorated 3 months post-GKRS, whereas acute changes in DTI parameters of the optic nerves resolved within 6-8 months. DTI of central and posterior optic radiations did not differ significantly following radiosurgery; 6-8 months after radiosurgery, visual function was stable in 14 (56%) patients and improved in 11 (44%), showing no correlation with tumor size changes or DTI parameters. CONCLUSION: White Matter (WM) injury in the optic pathways can be induced by Gamma Knife radiosurgery targeted to sellar and parasellar tumors. Following GKRS, microstructural abnormalities occurred in the optic radiations as well as the optic nerves within the first post-treatment year. Our findings could support modifications to radiosurgical treatment strategies to minimize the risk of permanent WM injury.

Stereotactic radiosurgery for tumors of the pineal region: A single-center experience.

Tumors of the pineal region (TPRs) are rare neoplasms that are surgically challenging to resect. Conventional treatment strategies are available, but gamma knife radiosurgery (GKRS) is an alternative approach. This study presents a single-center experience with GKRS performed for TPR with and without histopathological diagnoses. The cases of 25 patients with TPRs treated with GKRS were retrospectively analyzed. Thirteen of these 25 patients had histopathological confirmation, and 13 had elevated serum alpha-fetoprotein and beta-human chorionic gonadotropin levels. The 25 patients had a mean follow-up duration of 61 months. The total response rate to GKRS was 60%, and a 53.8% decrease in the alpha-fetoprotein and beta human chorionic gonadotropin levels was observed. The findings of this study indicate that GKRS is a safe procedure for TPRs, even in the event of insufficient histopathological findings. This treatment approach provides increased Karnofsky performance scores and an extended life expectancy.

Thioredoxin System and miR-21, miR-23a/b and let-7a as Potential Biomarkers for Brain Tumor Progression: Preliminary Case Data.

BACKGROUND: The thioredoxin system and microRNAs (miRNAs) are potential targets for both cancer progression and treatment. However, the role of miRNAs and their relation with the expression profile of thioredoxin system in brain tumor progression remains unclear. METHODS: In this study, we aimed to determine the expression profiles of redox components Trx-1, TrxR-1 and PRDX-1, and oncogenic miR-21, miR-23a/b and let-7a and oncosuppressor miR-125 in different brain tumor tissues and their association with increasing tumor grade. We studied Trx-1, TrxR-1, and PRDX-1 messenger RNA expression levels by quantitative real-time polymerase chain reaction and protein levels by Western blot and miR-23a, miR-23b, miR-125a, miR-21, and let-7a miRNA expression levels by quantitative real-time polymerase chain reaction in 16 glioma, 15 meningioma, 5 metastatic, and 2 benign tumor samples. We also examined Trx-1, TrxR-1, and PRDX-1 protein levels in serum samples of 36 patients with brain tumor and 37 healthy volunteers by enzyme-linked immunosorbent assay. RESULTS: We found that Trx-1, TrxR-1, and PRDX-1 presented high messenger RNA expression but low protein expression in low-grade brain tumor tissues, whereas they showed higher protein expression in sera of patients with low-grade brain tumors. miR-23b, miR-21, miR-23a, and let-7a were highly expressed in low-grade brain tumor tissues and positively correlated with the increase in thioredoxin system activity. CONCLUSIONS: Our findings showed that Trx-1, TrxR-1, miR-21, miR-23a/b, and let-7a might be used for brain tumor diagnosis in the clinic. Further prospective studies including molecular pathway analyses are required to validate the miRNA/Trx system regulatory axis in brain tumor progression.

Dynamic contrast-enhanced magnetic resonance imaging for evaluating early response to radiosurgery in patients with vestibular schwannoma.

PURPOSE: This study aimed to use dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to evaluate early treatment response in vestibular schwannoma (VS) patients after radiosurgery. METHODS: Twenty-four VS patients who underwent gamma knife radiosurgery were prospectively followed up for at least four years. DCE-MRI sequences, in addition to standard MRI protocol, were obtained prior to radiosurgery, at 3 and 6 months. Conventionally, treatment responses based on tumor volume changes were classified as regression or stable (RS), transient tumor enlargement (TTE), and continuous tumor enlargement (CTE). DCE-MRI parameters, such as Ktrans, Kep and Ve, were compared according to follow-up periods and between groups. The diagnostic performance was tested using receiver operating characteristic (ROC) curves. RESULTS: Changes in tumor volume were as follows at the last 48 months of follow-up: RS in 11 patients (45.8%), TTE in 10 patients (41.7%), and CTE in three patients (12.5%). The median time required to distinguish TTE from CTE using conventional MRI was 12 months (range 9-18). The Ktrans and Ve were significantly decreased in patients with RS and TTE at 3 and 6 months, but did not differ significantly in patients with CTE. There were no significant differences in Ktrans and Ve between patients with RS and TTE at 3 and 6 months. Both Ktrans and Ve demonstrated high diagnostic performance in evaluating early treatment response to radiosurgery in patients with VS. CONCLUSION: DCE-MRI may aid in the monitoring and early prediction of treatment response in patients with VS following radiosurgery.

Stereotactic radiosurgery for cerebral cavernous malformation: comparison of hemorrhage rates before and after stereotactic radiosurgery.

OBJECTIVE: Cerebral cavernous malformation (CM) is an angiographically occult vascular pathology. Although microsurgery is the gold standard treatment to control the symptoms of CM, resection carries high risk in some situations, especially eloquent areas. The objective was to evaluate annual hemorrhage rates (AHRs) before and after stereotactic radiosurgery (SRS) treatment of cerebral CM in different locations. METHODS: A total of 195 patients (119 women and 76 men) with CM treated at the Gazi University Gamma Knife Center between April 2005 and June 2017 were analyzed. The mean ± SD follow-up period was 67.4 ± 31.1 months (range 12 days to 170 months). AHR before SRS, AHR after SRS, morbidity associated with radiation, seizure control rate after SRS, lesion volume, coexistence with developmental venous anomaly, and SRS treatment parameters were analyzed, with evaluation of radiological data and clinical charts performed retrospectively. The seizure control rate was assessed using the Engel outcome scale. RESULTS: The AHR before SRS was 15.3%. Application of SRS to these patients significantly reduced the AHR rates to 2.6% during the first 2 years after treatment and to 1.4% thereafter. Favorable seizure control (Engel class I and II) after radiosurgery was achieved in 23 patients (88.5%) with epilepsy. Radiation-related temporary complications occurred in 15.4% of patients, and permanent morbidity occurred in 4.6%. CONCLUSIONS: SRS is a safe and effective treatment modality for reducing the hemorrhage risk of CM. The authors suggest that SRS should be considered for the treatment of patients with CM, high surgical risks, and hemorrhage history, instead of a using a wait-and-see policy.

Stereotactic Radiosurgery after Subtotal Resection of Critically-Located Grade I Meningioma: A Single-Center Experience and Review of Literature.

AIM: To analyze the results of stereotactic radiosurgery in 295 patients with residual Grade I meningiomas located at parasellar region, petroclival region, cerebellopontine angle and parasagittal region. MATERIAL AND METHODS: A total of 295 patients with Grade 1 residual Meningiomas (197 women, 98 men), who were treated by adjuvant radiosurgery in Gazi University Gamma Knife Center between 2004-2015 were analyzed. WHO Grade 2 and 3 meningiomas were not included in our study. Minimum radiological follow-up was 24 months. The median follow-up was 54 months. The tumor volume, location, treatment dose, morbidity, progression free survival and tumor control rate were analyzed. RESULTS: The median tumor volume was 5.2 cm3 (0.04-39.7), median age was 50 (20-80), median dose was 14 Gy and tumor control rate was 94.5% (stationary in 85.0%, volume reduction in 9.5%). Increase in tumor volume was seen in 16 patients (5.5%) and re-operation was performed in 5 of them (1.6%). Stereotactic radiosurgery was performed again for 8 patients (2.7%).The location of the tumors was as follows: 39.3% parasellar region, 20% cerebellopontine angle, 13.6% petroclival and 27.1% was parasagittal, falcine or convexity. Major morbidities were detected in 6 (2%) patients. Minor morbidities were detected in 18 (6.1%) patients. CONCLUSION: Stereotactic radiosurgery is an effective and safe treatment modality for residual Grade I meningiomas.

Different Aspects on Clinical Presentation of Developmental Venous Anomalies: Are They as Benign as Known? A Single Center Experience.

BACKGROUND: Cerebral developmental venous anomalies (DVAs) are frequently diagnosed incidentally owing to the advances in neuroimaging. They are regarded as clinically insignificant due to their supposed quiescent existence which the authors aimed to contradict in this paper. AIM: In the aim of constituting a better understanding of clinical presentation of DVAs and making an estimation regarding the probability of resulting in a hemorrhage, the authors presented their experiences with a case series of DVAs. METHODS: A retrospective analysis was carried out among patients who underwent brain MRI in a radiology department of a university between January of 2019 and January of 2020. RESULTS: A total of 101 patients with DVA were extracted. 38 patients had isolated DVAs, while 63 patients had various accompanying cerebral pathologies, mostly cavernomas (39 patients) and AVMs (11 patients). The main complaints leading investigation were headache, dizziness, ataxia, nausea\vomiting, seizures and focal neurological deficits. 41 patients were truly symptomatic with indicative findings of seizures, neurological deficits or intracranial hemorrhages, and 12 of them had solitary DVAs. 22 patients presented with hemorrhages, and of them, 10 had only DVA, while the rest had some associated lesions, most often cavernoma. Of 22 patients with hemorrhage, 5 were operated, 5 were applied radiosurgery; while the rest were followed without any intervention. CONCLUSION: Although the symptoms in patients with DVA are generally charged on other associated pathologies, the fact that isolated DVAs may occasionally be problematic in the range of minor symptoms and severe hemorrhage should not be underestimated.

A Comparison of Ramipril and Bevacizumab to Mitigate Radiation-Induced Brain Necrosis: An Experimental Study.

BACKGROUND: Bevacizumab, an anti-vascular endothelial growth factor (VEGF) antibody, is a new treatment approach for radionecrosis. In our study, we compared the prophylactic and therapeutic usage of a promising agent, ramipril (an angiotensin-converting enzyme inhibitor), with that of bevacizumab for reducing radiation-induced brain injury after high-dose stereotactic radiosurgery (SRS). METHODS: A total of 60 Wistar rats were used. The rats were irradiated with a single dose of 50 Gy using a Leksell Gamma Knife device. Bevacizumab and ramipril were administered in the prophylactic protocol (starting the first day of SRS) and in the therapeutic protocol (starting the fourth week of SRS). Their usage was continued until 12 weeks, and the right frontal lobes of the rats were examined histologically (hematoxylin and eosin stain) and immunohistochemically (hypoxia-inducible factor [HIF]-1α, VEGF, and CD31 antibody expression). RESULTS: The expression of VEGF, HIF-1α, and CD31 had significantly increased at 12 weeks after SRS compared with the control group. The addition of bevacizumab or ramipril to SRS significantly mitigated the histological severity of radiation injury and the expression of VEGF, HIF-1α, and CD31. However, the prophylactic use of bevacizumab and ramipril seemed to be more effective than therapeutic administration. Our results also revealed that the greatest benefit was achieved with the use of prophylactic administration of bevacizumab compared with other treatment protocols. CONCLUSIONS: Ramipril might be a promising agent for patients with radionecrosis. Clinical studies are required to investigate the effective and safe doses of ramipril, which is an inexpensive, well-tolerated drug that can cross the blood-brain barrier.

Correlation of language lateralization with resting state hippocampal connectivity in temporal lobe epilepsy patients

Background/aim: The main purpose of this study is to evaluate the resting state hippocampal connectivity with language areas and to correlate them with laterality index calculations on single subject basis, hence to present hippocampal lateralization for language with rs-fMRI. Materials and methods: Task based and rs-fMRI data were gathered from a total of 45 subjects in 3T scanner. BrainVoyager QX, SPM, and CONN softwares were used for data analysis. LI score of each subject was calculated and converted into normalized LI score (nLI). Intrahemispheric rs-connectivity analysis was performed between hippocampus and Broca's regions on both sides. Correlation between these variables was measured with SPSS software. Results: Right-TLE patients were found to have highest whereas left-TLE group were found to have lowest mean LI scores. Regarding hippocampal-lingual networks; left intrahemispheric connectivity values showed strong positive correlation with nLI values in left, right-TLE patients and healthy controls (P = 0.035, 0.014, 0.047). There were no significant correlation between right intrahemispheric connectivity values and nLI scores in all groups. Conclusions: This study seems to depict the existence of resting state hippocampal-lingual functional network which correlates well with lateralization of language function in the left hemisphere in both temporal lobe epilepsy patients and healthy controls.

Evaluation of brain FDG PET images in temporal lobe epilepsy for lateralization of epileptogenic focus using data mining methods

Background/aim: In temporal lobe epilepsy (TLE), brain positron emission tomography (PET) performed with F-18 fluorodeoxyglucose (FDG) is commonly used for lateralization of the epileptogenic temporal lobe. In this study, we aimed to evaluate the success of quantitative analysis of brain FDG PET images using data mining methods in the lateralization of the epileptogenic temporal lobe. Materials and methods: Presurgical interictal brain FDG PET images of 49 adult mesial TLE patients with a minimum of 2 years of postsurgical follow-up and Engel I outcomes were retrospectively analyzed. Asymmetry indices were calculated from PET images from the mesial temporal lobe and its contiguous structures. The J48 and the logistic model tree (LMT) data mining algorithms were used to find classification rules for the lateralization of the epileptogenic temporal lobe. The classification results obtained by these rules were compared with the physicians' visual readings and the findings of single-patient statistical parametric mapping (SPM) analyses in a test set of 18 patients. An additional 5-fold cross-validation was applied to the data to overcome the limitation of a relatively small sample size. Results: In the lateralization of 18 patients in the test set, J48 and LMT methods were successful in 16 (89%) and 17 (94%) patients, respectively. The visual consensus readings were correct in all patients and SPM results were correct in 16 patients. The 5-fold cross- validation method resulted in a mean correct lateralization ratio of 96% (47/49) for the LMT algorithm. This ratio was 88% (43 / 49) for the J48 algorithm. Conclusion: Lateralization of the epileptogenic temporal lobe with data mining methods using regional metabolic asymmetry values obtained from interictal brain FDG PET images in mesial TLE patients is highly accurate. The application of data mining can contribute to the reader in the process of visual evaluation of FDG PET images of the brain.

Results of Chordoma Patients Treated by Different Approaches in a Single Institution.

AIM: To discuss the optimal and recent treatment options based on clinical review of 16 chordoma patients. MATERIAL AND METHODS: Data of the patients diagnosed and treated between 1999 and 2017 in Gazi University School of Medicine has been collected through patients’ files and the electronic database of hospital records. Statistical analysis was applied to evaluate the correlation between the progression free survival and treatment modalities. RESULTS: Nine of the 16 patients were women (56.3%). Half of the patients had intracranially located tumors, whereas the other 50% of the sample had spinal (n=5) and sacral (n=3) chordomas. The median follow-up time was 51.7 months. Recurrence was observed in 50% of patients, while the median recurrence time equaled to 27.6 months. Multivariate analysis results showed that age, gender tumor size, intra or extracranial location of tumor, treatment modalities, subtotal or grosstotal resection of tumor, radiotherapy dose, and techniques were not associated with recurrence. On the other hand, 2 patients are still under chemoterapy (imatinib, bevacizumab) without evident of recurrent disease. CONCLUSION: Despite the fact that surgery remains to be the cornerstone of treatment, total resection is not reasonable for all patients with chordomas. For this reason, adjuvant treatment for ensuring local control is highly important. If the residual tumor is of a small volume, SBRT may provide more advantages. Targeted treatment or chemotheapeutic agents may also be benificial for maintanence therapy. As the clinical awareness about chordomas is based on our series, aggressive multi-modality treatment options should be applied in the adjuvant therapy.

The Effects of Minocycline on the Hippocampus in Lithium- Pilocarpine Induced Status Epilepticus in Rat: Relations with Microglial/Astrocytic Activation and Serum S100B Level.

AIM: To investigate possible correlations between serum S100B levels and microglial/astrocytic activation in status epilepticus (SE) in lithium-pilocarpine-exposed rat hippocampi and whether serum S100B levels linearly reflect neuroinflammation. Additionally, to assess the effects of minocycline (M), an inhibitor of neuroinflammation. MATERIAL AND METHODS: Rats were divided into 4 groups (6/group), namely, control (C), sham, SE, and SE+M. Animals were exposed to lithium-pilocarpine to induce SE in the SE and SE+M groups. Cardiac blood was collected to measure S100B levels, and coronal brain sections including the hippocampus were prepared to examine microglial/astrocytic activation and to evaluate neuroinflammation at day 7 of SE. RESULTS: Serum S100B levels, OX42 (+) microglia in CA1, and GFAP (+) astrocytes in both CA1 and dentate gyrus (DG) were higher in the SE+M group than in the C group. Most importantly, highly positive correlations were found between S100B levels and microglial activation in CA1, apart from astrocytic activation in CA1 and DG. Unexpectedly, microglial activation in CA1 and astrocytic activation in DG were also enhanced in the SE+M group compared with the C group. Moreover, M administration reversed the neuronal loss observed in DG during SE. CONCLUSION: These results suggest that serum S100B is a candidate biomarker for monitoring neuroinflammation and that it may also help predict diagnosis and prognosis.

Investigation of the Effect of Alemtuzumab in an Experimental Spinal Cord Trauma Model in Rats.

OBJECTIVE: Spinal cord injuries generate the most negative response to medical treatment among all general body injuries. This important morbidity is thought to be caused by a complex secondary damage mechanism. In the present study, we examined the neuroprotective effects of alemtuzumab in a spinal cord trauma model. METHODS: We divided 24 Long-Evans male rats into 4 groups (n = 6 per group). Laminectomy was performed at T5-T8 in all groups. Trauma was applied using the Yasargil temporary aneurysm clip for 60 seconds at these spinal cord levels in all groups, except for group 1. Next, 1 mg/kg of alemtuzumab was administered to each rat in groups 3 and 4. A functional evaluation was performed on days 1, 3, and 5 in groups 1, 2, and 4, and the rats were then sacrificed. The rats in group 3 were sacrificed on the third postoperative day to observe the early effects of alemtuzumab. The biochemical examination findings of malondialdehyde and glutathione in plasma and tissue samples and histopathological findings of the spinal cord were evaluated and compared by statistical analysis. RESULTS: The inflammatory findings in the trauma group were not seen in either group treated with alemtuzumab. The clinical motor examination and inclined plane test results were also significantly better in these groups. CONCLUSION: Our results have shown that alemtuzumab might prevent spinal cord injury after trauma and is a histopathologically and biochemically strong anti-inflammatory, antioxidant, and neuroprotective agent.

Aggravation of seizures and status epilepticus after vagal nerve stimulation therapy: the first pediatric case and review of the literature.

BACKGROUND: We describe the first child with drug-resistant epilepsy in whom vagus nerve stimulation aggravated seizures and emerged status epilepticus after the increase in vagal nerve stimulation current output. OBJECTIVE: A 13-year-old girl presented with refractory secondary generalized focal epilepsy. Vagal nerve stimulator was implanted because of drug-resistant epilepsy. After the increase of vagal nerve stimulator current output to a relatively high level, the patient experienced seizure aggravation and status epilepticus. CONCLUSION: We conclude that vagus nerve stimulation may induce paradoxical seizures and may lead to status epilepticus, similarly to some antiepileptic drugs.

Effects of vagus nerve stimulation on heart rate variability in children with epilepsy.

PURPOSE: The aim of this study was to evaluate the effects of vagus nerve stimulation (VNS) on heart rate variability (HRV) in children with epilepsy. METHODS: The subgroups of HRV, namely time domain (Standard deviation of NN interval (SDNN), SDNN index, Standard deviation of the averages of NN intervals (SDANN), Root mean square of successive differences (RMMSD), Adjacent NN intervals differing by more than 50 ms in the entire recording divided by the total number of all NN intervals (PNN50), triangular index) and frequency domain (Low-frequency (LF), High-frequency (HF), LF/HF), were investigated in 20 pediatric patients before and after 6 and 12months of VNS treatment during day and night by comparing their data with those of 20 control subjects. In addition, subgroups of age, epilepsy duration and localization, and antiepileptic drugs (AEDs) were also evaluated if they had further effects on basal HRV levels. RESULTS: Increased heart rates (HRs); decreased SDNN, SDANN, RMMSD, and PNN50; and increased LF/HF ratios were identified before VNS therapy (p<0.05). Even though remarkable improvement was seen after 6months of VNS treatment (p<0.05), no further changes were observed in 12-month compared with 6-month levels (p>0.05) in all parameters, still even significantly lower than those of controls (p<0.05). Longer duration of epilepsy and localization of epileptic focus, such as in the temporal lobe, were also found to further contribute to diminished basal HRV levels (p<0.05). CONCLUSION: The cardiovascular system is under deep sympathetic influence in children with epilepsy. Although VNS seems to provide a substantial improvement by achieving increased parasympathetic effects in short-term therapy, the levels were still lower than those of healthy children after either short- or long-term therapy. Therefore, impaired cardiovascular autonomic regulation may be associated with the epileptic process itself as well as with the contribution of some additional factors. Overall, different aspects such as age, epilepsy duration, epileptic focus, seizure frequency, and AEDs should also be considered for their further possible effects on HRV during VNS therapy.

Outcomes of resective surgery in children and adolescents with focal lesional epilepsy: The experience of a tertiary epilepsy center.

OBJECTIVE: This study aimed to investigate the efficacy of resective surgery in children with focal lesional epilepsy by evaluating the predictive value of pre- and postsurgical factors in terms of seizure freedom. METHODS: This study included 61 children aged between 2 and 18years who were admitted to the pediatric video-EEG unit for presurgical workup. Each patient was evaluated with a detailed history, video-EEG, neuroimaging, and postsurgical outcomes according to Engel classification to predict postsurgical seizure freedom. All the possible factors including history, etiology, presurgical evaluation, surgical procedures, and postsurgical results were analyzed for their predictive value for postoperative seizure freedom. RESULTS: Of the 61 patients, 75% were diagnosed as having temporal lobe epilepsy (TLE), and 25% were diagnosed with extra-TLE. Two years after the surgery, 78.6% were seizure-free, of which 89% had TLE, and 50% had extra-TLE (p<0.05). Patients were more likely to have a favorable outcome for seizure freedom if they had rare seizure frequency, focal EEG findings, and focal seizures; had a temporal epileptogenic zone; or had TLE and hippocampal sclerosis. On the other hand, patients were more likely to have unfavorable results for seizure freedom if they had younger age of seizure onset, frequent seizures before the surgery, a frontal or multilobar epileptogenic zone, secondarily generalized seizures, extra-TLE with frontal lobe surgery, or focal cortical dysplasia. SIGNIFICANCE: Resective surgery is one of the most effective treatment methods in children with intractable epilepsy. A history of young age of seizure onset, frequent seizures before surgery, secondarily generalized seizures, a multilobar epileptogenic zone, frontal lobe surgery, and focal cortical dysplasia (FCD) are the most important predictive factors indicating that a patient would continue having seizures after surgery. On the other hand, focal seizure semiologies, temporal lobe localization, and hippocampal sclerosis indicate that a patient would have better results in terms of seizure freedom.

Long term effect of vagus nerve stimulation in pediatric intractable epilepsy: an extended follow-up.

PURPOSE: Over the past two decades, vagus nerve stimulation (VNS) has become an accepted and viable treatment modality for intractable epilepsy both in children and adults. Earlier studies have demonstrated short-term seizure outcomes, usually for up to 5 years; so far, none have reported an extended outcome in children. We aimed to assess long term seizure outcome in children with intractable epilepsy for more than 5 years. METHODS: We identified patients who had VNS implantation for treatment of intractable epilepsy from March 2000 to March 2015 at our Epilepsy Center and collected data including demographic, age at epilepsy onset and VNS implantation, duration of epilepsy, seizure type, number of antiepilepsy drugs (AEDs), and monthly seizure frequency before VNS implantation and at the last clinic visit. Phone surveys were conducted with patients without recent clinic follow-up. RESULTS: Fifty-six patients (aged 4-17 at the time of implant) are the subjects of the study. Seizure reduction of >50 % was achieved in 9.8 % (6th month), 24 % (2nd year), 46.4 % (3rd year), and 54 %(5th year), and overall 35 (62.5 %) of the 56 subjects had a greater than 50 % reduction in seizure frequency at the last follow-up. Eleven patients became seizure free. The results, once obtained, were maintained steadily or even improved over time without any loss of efficacy during the follow-up. The only parameter, significantly related with clinical response, was age at seizure onset. The most frequent adverse events were hoarseness, cough, sore throat, and anorexia, experienced by 13 patients. Two patients had local wound infections and lead to the removal of the stimulator. An improvement in alertness, attention, and psychomotor activity, independent of the efficacy of vagal nerve stimulation, was observed in 8 patients. CONCLUSION: To our knowledge, this is the first pediatric study evaluating seizure outcome over more than 5 years of follow-up, and demonstrates a favorable seizure outcome of >50 % seizure frequency in 62.5 % of patients and seizure freedom in 11 patients. It is well tolerated over an extended period of time.

Surgical outcome in patients with MRI-negative, PET-positive temporal lobe epilepsy.

PURPOSE: The purpose of this study was to determine the long-term surgical outcomes of magnetic resonance imaging (MRI)-negative, fluorodeoxyglucose positron emission tomography (FDG-PET)-positive patients with temporal lobe epilepsy (TLE) and compare them with those of patients with mesial temporal sclerosis (MTS). METHODS: One hundred forty-one patients with TLE who underwent anterior temporal lobectomy were included in the study. The surgical outcomes of 24 patients with unilateral temporal hypometabolism on FDG-PET without an epileptogenic lesion on MRI were compared with that of patients with unilateral temporal hypometabolism on FDG-PET with MTS on MRI (n=117). The outcomes were compared using Engel's classification at 2 years after surgery. Clinical characteristics, unilateral interictal epileptiform discharges (IEDs), histopathological data and operation side were considered as probable prognostic factors. RESULTS: Class I surgical outcomes were similar in MRI-negative patients and the patients with MTS on MRI (seizure-free rate at postoperative 2 years was 79.2% and 82% in the MRI-negative and MTS groups, respectively). In univariate analysis, history of febrile convulsions, presence of unilateral IEDs and left temporal localization were found to be significantly associated with seizure free outcome. Multivariate analysis revealed that independent predictors of a good outcome were history of febrile convulsions and presence of unilateral IEDs. CONCLUSION: Our results suggest that epilepsy surgery outcomes of MRI-negative, PET positive patients are similar to those of patients with MTS. This finding may aid in the selection of best candidates for epilepsy surgery.