Bilateral Temporal Hypometabolism in Epilepsy

Summary: Purpose: Positron emission tomography (PET) has proven useful in epilepsy surgery for its ability to identify unilateral temporal hypometabolism (UTH), which is predictive of good surgical outcome. The significance of bilateral temporal hypometabolism (BTH) is not known.
Methods: We identified all patients who had marked bilateral reduction in temporal lobe metabolism relative to the cerebellar hemispheres and compared their clinical features and treatment outcomes with those of control patients with UTH.
Results: BTH was evident in 10% of PET scans for epilepsy at our institution. We compared these patients with age-matched controls with UTH. The BTH patients had a higher percentage of generalized seizures; were more likely to have bilateral, diffuse or extratemporal seizure onsets; and had bilateral or diffuse magnetic resonance imaging (MRI) findings. UTH patients were more likely to have unilateral mesial temporal atrophy on MFU. Even when electrical seizure onsets were well localized, surgical outcomes were markedly worse in these patients than in controls. Medical treatment was also less successful. Social and cognitive functioning was worse in the BTH group. The only death occurred in the group with BTH.
Conclusions: Patients with BTH have features distinct from those with UTH and have a worse prognosis for seizure remission after surgery.     

FDG-PET and MRI in temporal lobe epilepsy: relationship to febrile seizures, hippocampal sclerosis and outcome

Objective – To correlate the volumetric head magnetic resonance imaging (MRI) and fluorodeoxyglucose-positron emission tomography (FDG-PET) scan findings with the history, intracarotid amobarbital procedure, pathology, and outcome in patients with medically refractory temporal lobe epilepsy. Material and methods – Thirty-eight patients with temporal lobe epilepsy treated surgically following a comprehensive presurgical evaluation. Follow-up ranged from 12 to 44 months. Results – Volumetric MRI showed ipsilateral hippocampal atrophy in 29 (76%), and PET scan showed ipsilateral temporal hypometabolism (PET-TH) in 31 (81.5%) of patients. Eighty-three percent of those patients with hippocampal sclerosis on MRI (MRI-HS) had ipsilateral PET-TH. Sixty-six percent of patients with MRI-HS had a history of prolonged febrile convulsions or a childhood febrile illness accompanied by convulsions, and 77% of patients with MRI-HS had pathologically proven hippocampal sclerosis (HS). Ninety percent became seizure free or had rare seizures. Conclusion – FDG-PET scans and head MRIs were complementary; 95% of patients had either MRI-HS or temporal hypometabolism. MRI-HS correlated with a history of febrile seizures and pathologically demonstrated hippocampal sclerosis. Ninety-three percent of patients had focal functional deficits on the epileptogenic side. Concordance between PET temporal hypometabolism and MRI-HS correlated with better outcome.     

Presurgical evaluation in refractory epilepsy secondary to meningitis or encephalitis: bilateral memory deficits often preclude surgery.

We investigated the clinical features and surgical outcome of 17 patients with refractory epilepsy secondary to CNS infection who were referred to a tertiary center for presurgical evaluation. Six patients had a history of meningitis and 11 patients had a history of encephalitis. Median age at infection was three years (40 days-40 years). Time to seizure onset was shorter in the encephalitis group (median of 0.9 years versus 5.9 years in the meningitis group). MRI showed unilateral mesial temporal sclerosis (MTS) in all but one patient with meningitis (5/6). MRI in the encephalitis group showed unilateral MTS (four patients), bilateral MTS (three), porencephalic cysts (one) or no significant findings (three). Seizure semiology, following analysis of 127 seizures, included automotor seizures, complex motor/hypermotor seizures, dialeptic seizures and bilateral asymmetric tonic seizures. Neuropsychological assessment in patients with MTS frequently showed bilateral memory impairment (7 out of 12 MTS-patients), even in 4 patients with unilateral MTS, precluding epilepsy surgery. Six patients (two meningitis and four encephalitis patients) underwent a temporal lobe resection. All patients are either seizure-free (Class 1a) or are having only auras after surgery. One patient from the meningitis group underwent functional hemispherectomy and he is also seizure-free. In our series, MTS was the most common finding in refractory epilepsy after CNS infections. Bilateral memory deficits were often encountered in patients with MTS, even when unilateral, these deficits being a limiting factor for surgery. Good surgical outcome can be expected in selected patients with unilateral MTS and congruent memory deficits.     

Seizure outcome after anterior temporal lobectomy and its predictors in patients with apparent temporal lobe epilepsy and normal MRI

PURPOSE: Very little reliable information is available regarding the role of anterior temporal lobectomy (ATL), optimal presurgical evaluation strategy, post-ATL seizure outcome, and the factors that predict the outcome in patients with medically refractory temporal lobe epilepsy (TLE) and normal high-resolution magnetic resonance imaging (MRI). To be cost-effective, epilepsy surgery centers in developing countries will have to select candidates for epilepsy surgery by using the locally available technology and expertise. METHODS: We reviewed the electroclinical and pathological characteristics and seizure outcome of 17 patients who underwent ATL for medically refractory TLE after being selected for ATL based on a noninvasive selection protocol without the aid of positron emission tomography (PET) or single-photon emission computed tomography (SPECT), despite a normal preoperative high-resolution MRI. RESULTS: Seven (41%) patients achieved an excellent seizure outcome; five of them were totally seizure free. An additional five (29%) patients had >75% reduction in seizure frequency. The following pre-ATL factors predicted an excellent outcome: antecedent history of febrile seizures, strictly unilateral anterior temporal interictal epileptiform discharges (IEDs), and concordant type 1 ictal EEG pattern. All the five patients with pathologically verified hippocampal formation neuronal loss were seizure free. The presence of posterior temporal, bilateral temporal, and generalized IEDs portended unfavorable post-ATL seizure outcome. CONCLUSIONS: A subgroup of patients destined to have an excellent post-ATL outcome can be selected from MRI-negative TLE patients by using history and scalp-recorded interictal and ictal EEG data. The attributes of these patients are antecedent history of febrile seizures, strictly unilateral anterior IEDs, and concordant type 1 ictal EEG pattern.     

Paradoxical imaging findings in cerebral gliomas

Gliomas represent approximately one-third of all intracranial tumors in adults and commonly present clinically with seizures. We report two seizure patients with paradoxical imaging findings on preoperative grading of their cerebral gliomas. A 53-year-old man with a history of temporal lobe epilepsy originating from a mass in the right medial temporal region (patient 1) and a 44-year-old man with a history of predominantly left sided sensory seizures with a mass in the right posterior parietal region (patient 2) underwent presurgical evaluation including MRI and glucose PET, followed by surgery to remove cerebral tumors associated with seizure onset. Preoperatively, patient 1 had a homogenous non-enhancing lesion on MRI and hypometabolism on PET imaging, suggesting a low-grade tumor. Postoperative histopathology was consistent with a glioblastoma multiforme (grade IV). Patient 2 had a heterogeneous lesion with cyst formation, edema, and contrast enhancement on preoperative MRI imaging, and interictal hypermetabolism on PET scan, thus suggesting a high-grade tumor. Postoperative histopathology was consistent with an oligodendroglioma (grade II) without anaplastic features. We conclude preoperative grading of cerebral gliomas may be inaccurate occasionally even in cases with concordant structural and functional imaging findings. This should be considered when counseling patients.     

Callosotomy and subsequent surgery for children with refractory epilepsy

Callosotomy has been considered as a palliative therapy for refractory epilepsy patients with non-focal onset seizures. Residual partial seizures and unilateral epileptiform discharges on electroencephalography (EEG) are sometimes observed after callosotomy. These findings suggest that some patients may be candidates for subsequent resective surgery. Of 149 children who received a callosotomy, resective/disconnective surgery was subsequently performed in 19 patients. Most patients had generalized seizures and epileptiform discharges on EEG before callosotomy. Two-third had normal neuroimaging studies at initial presurgical evaluation. After callosotomy, ictal symptoms evolved into asymmetric features suggesting partial onset seizures. Post-callosotomy EEG showed completely lateralized or localized epileptiform discharges responsible for residual partial seizures in 16 of 19 patients. Fifteen patients underwent resective surgery of the unilateral frontal lobe, and the remaining received hemispherotomy or posterior quadrantectomy. After subsequent surgery, favorable seizure outcomes were obtained in 11 patients (57.9%). Favorable seizure outcomes may be achieved with callosotomy and subsequent surgery in selected patients who are not candidates for a conventional resective surgery at initial presurgical evaluation.     

Is 11C-flumazenil PET superior to 18FDG PET and 123I-iomazenil SPECT in presurgical evaluation of temporal lobe epilepsy?

OBJECTIVE: To determine the contribution of 18FDG PET, 11C-flumazenil PET, and 123I-iomazenil SPECT to the presurgical evaluation of patients with medically intractable complex partial seizures. METHODS: Presurgical evaluation was performed in 23 patients, who were considered candidates for temporal lobe resective surgery (14 females and nine males with a median age of 34 (range 13 to 50) years). The presurgical diagnosis was based on seizure semiology as demonstrated with ictal video recording, ictal and interictal scalp EEG recordings, and MRI. RESULTS: Eighteen patients had convergent findings in clinical semiology, interictal and ictal EEG with scalp and sphenoidal electrodes, and MRI that warranted surgery without depth EEG (DEEG). In five patients with insufficient precision of localisation, DEEG with intracerebral and subdural electrodes was performed. MRI showed abnormalities in 22 out of 23 patients. Of these 22, 18 had mesial temporal sclerosis. This was limited to the mesial temporal lobe in four and more widespread in the temporal lobe in 14 patients. In one patient only enlargement of the temporal horn was found and in three others only white matter lesions were detected. 18FDG PET showed a large area of glucose hypometabolism in the epileptogenic temporal lobe, with an extension outside the temporal lobe in 10 of 23 patients. Only in one of these patients DEEG showed extratemporal abnormalities that were concordant with a significant extratemporal extension of hypometabolism in 18FDG PET. 18FDG PET was compared with the results of scalp EEG: in none of the patients was an anterior temporal ictal onset in scalp EEG related to a maximum hypometabolism in the mesial temporal area. By contrast, the region of abnormality indicated by 11C-flumazenil PET was much more restricted, also when compared with DEEG findings. Extension of abnormality outside the lobe of surgery was seen in only two patients with 11C-flumazenil and was less pronounced compared with the intratemporal abnormality. Both 18FDG PET and 11C-flumazenil PET reliably indicated the epileptogenic temporal lobe. Thus these techniques provide valuable support for the presurgical diagnosis, especially in patients with non-lesional MRI or non-lateralising or localising scalp EEG recordings. In those patients in whom phase 1 presurgical evaluation on the basis of classic methods does not allow a localisation of the epileptogenic area, PET studies may provide valuable information for the strategy of the implantation of intracranial electrodes for DEEG. Previous studies have suggested that 11C-flumazenil binding has a closer spatial relationship with the zone of ictal onset than the area of glucose hypometabolism, but this study suggests rather that the decrease in the 11C-flumazenil binding simply reflects a loss of neurons expressing the benzodiazepine-GABA receptor. 11C-flumazenil PET did not prove to be superior to 18FDG PET. CONCLUSION: In 21 patients sufficient material was obtained at surgery for a pathological examination. In 17 mesial temporal sclerosis, in one an oligodendroglioma grade B, in another a vascular malformation and in two patients no abnormalities were found. Although all 21 patients with pathological abnormality showed hypometabolic zones with 18FDG PET and a decreased uptake in 11C-flumazenil binding, there was no strong correlation between pathological diagnosis and functional abnormal areas in PET. Grading of medial temporal sclerosis according to the Wyler criteria showed no correlation with the degree of hypometabolism in either 18FDG or 11C-flumazenil PET. The interictal 123I-iomazenil SPECT technique was highly inaccurate in localising the lobe of surgery.     

Outcome after temporal lobectomy in bilateral temporal lobe epilepsy

We determined how noninvasive presurgical data relate to prognosis after temporal lobectomy in patients with independent bilateral temporal lobe (IBTL) complex partial seizures on the intracranial electroencephalogram (EEG). Between 1986 and 1994, 28 patients had IBTL seizures on intracranial EEG. Fifteen of these 28 patients underwent temporal lobectomy and 13 were not offered surgery. Of the 15 patients who had surgery, 10 patients became seizure-free. Magnetic resonance imaging (MRI) and the Wada test were the only variables associated with a seizure-free outcome. Seven of 10 seizure-free patients had a lateralized Wada result or the presence of unilateral hippocampal sclerosis, whereas none of the patients with persistent seizures had either of these findings. Variables not found to be predictive of a seizure-free outcome included location of scalp interictal spikes, degree of seizure-onset laterality, presence of early epilepsy risk factor, duration of epilepsy, and full-scale intelligence quotient. We conclude that MRI and the Wada test provide information of prognostic value in patients with bilateral temporal seizures independent of intracranial EEG data.     

The role of the intracarotid amobarbital procedure in evaluation of patients for epilepsy surgery

PURPOSE: To examine the role of the intracarotid amobarbital procedure (IAP) in the presurgical evaluation of patients with medically refractory localization-related epilepsy. METHODS: We retrospectively studied 111 patients who underwent cortical resective surgery at our center between 1991 and 1996. In patients with mesial temporal lobe epilepsy (mTLE), a presurgical determination of the epileptogenic zone was compared with localization based on IAP memory asymmetry scores, and with ultimate localization after resective surgery. In patients with neocortical or mesial frontal epilepsy, the IAP was evaluated for evidence of unilateral or bilateral poor memory performance. RESULTS: Of 68 patients with mTLE localized by noninvasive tests, 60 had concordant lateralized memory deficits on IAP. Eight patients had lateralized memory deficits on IAP that were discordant with noninvasive tests and with localization as determined by surgical outcome. All 11 mTLE patients requiring invasive EEG monitoring were correctly lateralized by IAP, including one patient in whom the noninvasive evaluation otherwise provided false lateralization. Of 32 patients with neocortical or mesial frontal lobe epilepsy, 21 displayed memory deficits on IAP. Of 10 patients with bilateral deficits, five had mesial frontal lobe epilepsy. In 13 patients with lateralized memory deficits, seven underwent electrode implantation in the mesial temporal lobe, and four ultimately underwent resection of an epileptogenic mesial temporal lobe in addition to a neocortical resection. CONCLUSIONS: In patients with mTLE, lateralized memory deficits on IAP usually confirm localization provided by noninvasive tests. However, in mTLE not well lateralized by the noninvasive evaluation, and in neocortical or mesial frontal epilepsy, the IAP may provide information regarding localization that ultimately alters surgical management.     

Pediatric intractable epilepsy: the role of presurgical evaluation and seizure outcome

Surgical experience with long-term follow-up is limited in childhood intractable epilepsy, compared with adult epilepsy. To assess the role of each presurgical evaluation modality and to identify prognostic factors for favorable seizure control after epilepsy surgery, 38 children with intractable epilepsy who underwent surgery were retrospectively reviewed. Among the available preoperative evaluation modalities, PET and neuropsychological testing showed the highest rates of positive results, whereas MRI was the most concordant with EEG findings. During a follow-up period of at least 12 months, 26 of the 38 patients showed favorable seizure control (Engel classifications I and II). The best seizure control was achieved in patients with a temporal resection and discrete lesion on magnetic resonance imaging. In spite of the invasive study, the less satisfactory results followed an extratemporal resection. We conclude that epilepsy surgery benefits children with intractable epilepsy and that the role of invasive study should be re-established according to the area of resection and presence of discrete lesion on MRI. Received: 23 June 1999 Revised: 7 August 1999     

18F-FCWAY and 18F-FDG PET in MRI-negative temporal lobe epilepsy

Background: Positron emission tomography (PET) with ¹⁸F‐fluorodeoxyglucose (FDG) shows widespread hypometabolism even in temporal lobe epilepsy (TLE) patients with mesial temporal foci. ¹⁸F‐trans‐4‐fluoro‐N‐2‐[4‐(2‐methoxyphenyl) piperazin‐1‐yl]ethyl‐N‐(2‐pyridyl)cyclohexane carboxamide (¹⁸F‐FCWAY) PET may show more specific 5‐HT_1A‐receptor binding reduction in seizure initiation than in propagation regions. ¹⁸FCWAY PET might be valuable for detecting epileptic foci, and distinguishing mesial from lateral temporal foci in MRI‐negative patients with TLE. Methods: We performed ¹⁸F‐FCWAY‐PET and ¹⁸F‐FDG‐PET in 12 MRI‐negative TLE patients who had had either surgery or subdural electrode recording, and 15 healthy volunteers. After partial volume correction for brain atrophy, free fraction‐corrected volume of distribution (V/f1) measurement and asymmetry indices (AIs) were computed. We compared ¹⁸F‐FCWAY‐PET and ¹⁸F‐FDG‐PET results with scalp video electroencephalography (EEG), invasive EEG, and surgical outcome. Results: Mean ¹⁸F‐FCWAY V/f1, compared with normal controls, was decreased significantly in fusiform gyrus, hippocampus, and parahippocampus ipsilateral to epileptic foci, and AIs were significantly greater in hippocampus, parahippocampus, fusiform gyrus, amygdala, and inferior temporal regions. Eleven patients had clearly lateralized epileptogenic zones. Nine had congruent, and two nonlateralized, ¹⁸F‐FCWAY PET. One patient with bitemporal seizure onset had nonlateralized ¹⁸F‐FCWAY‐PET. ¹⁸F‐FDG‐PET showed congruent hypometabolism in 7 of 11 EEG‐lateralized patients, bilateral hypometabolic regions in one, contralateral hypometabolism in one, as well as lateralized hypometabolism in the patient with bitemporal subdural seizure onset. Patients with mesial temporal foci tended to have lower superior and midtemporal ¹⁸F‐FCWAY V/f1 binding AI than those with lateral or diffuse foci. Conclusion: ¹⁸F‐FCWAY‐PET can detect reduced binding in patients with normal MRI, and may be more accurate than ¹⁸F‐FDG‐PET.     

发作间期PET和MR海马像在难治性颞叶癫癇术前定侧中的应用

目的 探讨发作间期18FDG-PET和MR海马像在难治性颞叶癫(?)（TLE）致(?)源术前定侧中的价值。方法 对17例药物难治性TLE患者术前定侧资料及术后随诊情况进行分析。结果 本组患者中,有12例（71％）患者MR显示海马硬化（HS）,海马萎缩与信号改变常共存,T2加权像和FLAIR序列有利于显示信号的改变。HS侧多提示为致(?)源侧。PET检查均显示有至少一侧颞叶低代谢改变,并常多发或范围弥散。PET与MR的定侧准确率分别是100％（13/13）、77％（10/13）,经x2检验两者间无差异（P>0.05）。结论　18FDG-PET和MR海马像在致(?)源定侧中的作用是互补的,当颞叶低代谢侧与海马硬化侧相一致时手术效果较好。     

Focal functional deficits in temporal lobe epilepsy on PET scans and the intracarotid amobarbital procedure: comparison of patients with unitemporal epilepsy with those requiring intracranial recordings

PURPOSE: To analyze the relationship between the intracarotid amobarbital procedure (IAP) and positron emission tomography (PET) and study the lateralizing value of these tests in patients with unitemporal epilepsy and those requiring intracranial recordings. METHODS: We compared 51 patients with unitemporal epilepsy (group1) with 26 patients in whom surface recordings failed to reveal a distinct unitemporal focus, necessitating invasive recordings (group 2). RESULTS: The brain magnetic resonance imaging (MRI) scans for group 1 showed mesial temporal sclerosis in 70.5% of the patients. PET showed unilateral temporal hypometabolism in 88%. In addition, 74.5% of the patients in group 1 had impaired memory on the epileptogenic side on the IAP, and 89.4% of those patients also had ipsilateral temporal hypometabolism on PET scans. All the group 1 patients underwent temporal resections. The pathologic examination showed hippocampal sclerosis in 72% of the patients. Eighty percent of group 1 patients became seizure free, and 16% had rare seizures (follow-up, 2-7 years). MRIs for group 2 showed mesial temporal sclerosis in 31% of the patients; PET scans showed temporal hypometabolism in 39%. The IAP was lateralized in 47.8%. Sixty-nine percent had temporal lobe resections. The pathologic examination showed hippocampal sclerosis in 44% of the patients. Forty-four percent of group 2 patients became seizure free, and 27.7% had rare seizures (follow-up, 2-8 years). CONCLUSIONS: Ninety-six percent of the patients with unitemporal foci had focal functional deficits on the epileptogenic side on 18-fluorodeoxyglucose-(FDG) PET scans, the IAP, or both. The results of the FDG-PET were predictive of impaired memory on the IAP. Memory impairment contralateral to the temporal hypometabolism found on the PET scans was never seen. These patients had an excellent outcome. In contrast, <50% of the patients requiring intracranial recordings had focal functional deficits, suggesting that more a diffuse pathology may account for their less favorable outcome.     

Correlation of severity of FDG-PET hypometabolism and interictal regional delta slowing in temporal lobe epilepsy

PURPOSE: We investigated the association of severity of hypometabolism detected by positron emission tomography (PET) with [(18)F]fluorodeoxyglucose (FDG) and persistence of interictal EEG focal slowing in patients with refractory temporal lobe epilepsy. METHODS: Eighty temporal lobes of 40 consecutive patients with intractable temporal lobe epilepsy (mean age, 43.5 years) were studied. All patients underwent video-EEG monitoring, magnetic resonance imaging (MRI), and FDG-PET. Patients with either normal MRI or with unilateral mesial temporal sclerosis, but no other structural abnormality, were included. Interictal EEG delta slowing was graded as none, infrequent (one episode or less/hour), intermediate (more than one episode/hour), or continuous. PET hypometabolism was graded as none, mild, moderate, or severe. RESULTS: The severity of temporal lobe hypometabolism with PET was significantly correlated with the amount of delta activity in the interictal EEG, independent of MRI findings (Spearman r = 0.46; p < 0.0005). CONCLUSIONS: This observation suggests related underlying pathophysiologic mechanisms for metabolic and electrical dysfunction in temporal lobe epilepsy.     

Value of HM-PAO SPECT in selective temporal lobe surgery for epilepsy

The purpose of this study was to assess the value of interictal ^99mTc-hexamethyl-propylenamine oxime (HM-PAO) single-photon emission computed tomography (SPECT) in the preoperative evaluation of epileptic patients with medically refractory seizures of temporal lobe (TL) origin. For this study, we selected 31 patients, who were preoperatively evaluated according to the Zürich presurgical protocol. All patients underwent selective amygdalohippocampectomy. Their surgery was based on ictal and interictal EEG recordings, using scalp and foramen ovale electrodes simultaneously. Postoperatively, 27 patients (87%) were seizure-free or had more than a 90% seizure reduction. All patients had preoperative interictal SPECT and magnetic resonance imaging (MRI) performed. Postoperative SPECT was performed in 18 patients. Preoperative MRI showed structural lesions in 20 cases, and 23 patients had abnormal histopathological findings. Preoperative SPECT determined correctly the primary epileptogenic area in 15 cases (48%), showing a zone of hypoperfusion restricted either to the TL (n = 9; 29%) or exceeding the TL structures (n = 6; 19%). In two patients (6%), the SPECT findings were located contralateral to the affected TL, and in one (3%) there was reduced regional cerebral blood flow in the ipsilateral basal ganglia. Thirteen patients (42%) had normal SPECT. No significant correlations were found among preoperative SPECT findings, MRI and histopathological results, and the postoperative clinical outcome. Based on the results of this study, we regard HM-PAO SPECT to be a useful confirmatory diagnostic tool in presurgical evaluation of epileptic patients. Given the present technological level, it cannot, however, replace the semi-invasive EEG methods.     

The relevance of somatosensory auras in refractory temporal lobe epilepsies

The purpose of this study is to look at the prevalence, characteristics, and prognostic value of somatosensory auras (SSAs) in patients who have undergone temporal lobe epilepsy (TLE) surgery to treat drug‐resistant focal epilepsy. We retrospectively reviewed all patients with drug‐resistant epilepsy who underwent TLE surgery at Cleveland Clinic between 2005 and 2010 (n = 333) to study the prevalence, characteristics, and prognostic implications of SSA in the context of TLE surgery. Analyses were performed using two seizure outcome definitions: complete seizure freedom and Engel classification. Of the 333 patients, 26 (7.8%) had SSA. Almost half (12 patients) had unilateral sensory symptoms, whereas the rest had bilateral symptoms. Tingling and numbness were the most frequently reported sensations. Compared to their non‐SSA counterparts, patients with SSA had the same clinical and imaging characteristics, but had a higher rate of breakthrough seizures (p = 0.03), although most (54%) were still able to achieve Engel class of I (p = 0.02). Based on our results we would encourage detailed presurgical testing, which may include an invasive evaluation to analyze the extent of the epileptogenic zone in patients with SSA and suspected TLE.     

Posterior cortex epilepsy secondary to ulegyria: Is it a surgically remediable syndrome?

Purpose: To examine whether surgery is indicated for posterior cortex epilepsy secondary to ulegyria. Patients and methods: Ten patients who underwent surgery for posterior cortex epilepsy with ulegyria and were followed for more than 2 years were included. All patients underwent comprehensive presurgical evaluations. Five patients underwent intracranial electroencephalography (EEG) studies. The posterior cortex including the magnetic resonance imaging (MRI) lesion was resected in all patients. Postoperative follow‐up period was 2–12 (mean 6) years. Results: Nine patients had a history of perinatal distress including asphyxia and prolonged labor. Age at seizure onset was 5–11 years, except one patient. Three patients had visual field defects preoperatively. Ulegyria was unilateral in four patients and bilateral but unilateral‐predominant in six patients. In most of the cases, the lesions were in the posterior cerebral artery area or the watershed area between middle cerebral and posterior cerebral arteries. In four of five patients who underwent intracranial EEG, seizure onset zones extended outside the lesions. Postoperative seizure outcome was Engel's class I in seven cases, and class III in three cases. Three of four patients whose seizure onset zones were not completely resected achieved class I outcome. Four of six patients with bilateral lesions achieved class I outcome. Conclusion: Ulegyria due to perinatal distress is considered to be a major cause of posterior cortex epilepsy. Long‐term postoperative seizure outcome is favorable. Resection of MRI lesion is important for seizure relief. Bilateral lesions should not be excluded from surgical indication. The usefulness of intracranial EEG may be limited.     

Does F-18 FDG-PET substantially alter the surgical decision-making in drug-resistant partial epilepsy?

ObjectiveThere is a dearth of information on the critical utility of positron emission tomography (PET) in choosing candidates for epilepsy surgery especially in resource-poor countries where it is not freely available. This study aimed to critically analyze the utility of FDG-PET in the presurgical evaluation and surgical selection of patients with DRE based on the results obtained through its use in our comprehensive epilepsy program.MethodsFrom 2008 to 2012, 117 patients with drug-resistant epilepsy underwent F-18 fluoro-deoxy-glucose (FDG) PET in our center. We utilized their data to audit the utility of PET in choosing/deferring patients for surgery.ResultsOf the 117 patients (age: 5–42 years) who underwent F-18 FDG-PET, 64 had normal MRI, and 53 had lesions. Electroclinical data favored temporal ictal onset in 48 (41%), extratemporal in 60 (51.3%), and uncertain lobar localization in 9 (7.7%). The topography of PET hypometabolism was localizing in 53 (45.3%), lateralizing in 12 (10.3%), and 52 (44.4%) had either normal or discordant results. In the nonlesional group, focal hypometabolism was concordant to the area of ictal onset in 27 (41.5%) versus 38 (58.5%) in the lesional group (p = 0.002). Greater concordance was noted in temporal lobe epilepsy (TLE) (78.0%) as compared to extratemporal epilepsy (ETPE) (28.6%) (p < 0.001). Positron emission tomography was more concordant in patients with mesial temporal sclerosis than in those with other lesions (82.8% versus 50%) (p = 0.033). Positron emission tomography helped in surgical decision-making in 68.8% of TLE and 23.3% of ETPE cases. Overall, 37 patients (31.6%) were directly selected for resective surgery based on PET results.ConclusionsPositron emission tomography, when utilized judiciously, remained an ancillary tool in the surgical selection of one-third of patients with drug-resistant partial epilepsy, although its utility as an independent tool is not very promising.     

Non-invasive examinations successfully select patients with medial temporal lobe epilepsy for anterior temporal lobectomy]

We retrospectively analyzed 8 patients with intractable medial temporal lobe epilepsy (MTLE) who underwent the anterior temporal lobectomy with hippocampectomy (ATL) without invasive examinations such as chronic subdural electrode recording. Five patients had a history of febrile convulsion. While all 8 patients had oral automatism, automatism of ipsilateral limbs with dystonic posture of contralateral limbs was demonstrated in 2 patients. Bilateral temporal paroxysmal activities on interictal EEG was observed in 4 patients and all patients had clear ictal onset zone on unilateral anterior temporal region. MRI demonstrated unilateral hippocampal sclerosis in 5 cases. Interictal FDG-PET depicted hypometabolism of the unilateral temporal lobe in all cases, however, ECD-SPECT failed to reveal the hypoperfusion of the unilateral temporal lobe in a case. Postoperatively, 7 cases became seizure free, and one had rare seizure. Non-invasive examinations, especially ictal EEG and concordant FDG-PET findings, in patients with oral automatism in seizure semiology, successfully select patients with MTLE for ATL.     

Preoperative evaluation for temporal lobe surgery.

Temporal lobe epilepsy (TLE), the most common form of partial epilepsy in adults is often refractory to medical treatment and in these patients epilepsy surgery is considered. Successful surgery is dependent on accurate localisation and lateralisation of the epileptogenic zone. The preoperative evaluation involves a series of assessments and investigations including detailed clinical history, interictal EEG, video-EEG monitoring, MRI, PET, SPECT, and neuropsychology and neuropsychiatric assessment. The role of each of these investigations and assessments in the preoperative evaluation is discussed. Advanced MR techniques including magnetic resonance spectroscopy, MR diffusion and MR perfusion have recently been assessed and are likely to enhance the pre-surgical evaluation of patients with TLE.The surgical outcome and preoperative investigations performed of 80 consecutive patients who underwent temporal lobe surgery between 1993 and 2002 at Royal Melbourne Hospital were reviewed. All patients had MRI, video-EEG monitoring and neuropsychology assessment and 56% a PET scan. During a mean follow-up of 5.9 years 75% had Class 1 outcome, 22% non-Class 1 outcome and 3% were lost to follow-up. The results of preoperative investigations were correlated with outcome. For interictal EEG, seizure semiology, ictal EEG, PET and neuropsychology assessment the surgical outcome of patients in whom results were concordant to side of surgery was compared with those discordant or non-lateralising. There was no significant difference. In 78 of 80 patients MRI revealed mesial temporal sclerosis or a foreign tissue lesion. The outcome was no different between these two groups. Results suggest that in patients with unilateral temporal lobe lesion on MRI and where ictal EEG is either concordant or non-lateralising, other investigations including PET, provide little additional prognostic information.