March 2006
Language and Motor fMRI Activation in Polymicrogyric Cortex
David Araujo, Draulio B. de Araujo, Octavio M. Pontes-Neto, Sara Escorsi-Rosset, Gustavo N. Simao, Lauro Wichert-Ana, Tonicarlo R. Velasco, Americo C. Sakamoto, Joao P. Leite, and Antonio C. Santos

Polymicrogyria (PMG) are disorders of cortical organization that may be due to genetic or prenatal causes. We analyzed the patterns of brain activation in polymicrogyric cortex in patients with epilepsy by blood oxygenation level dependent (BOLD) functional MRI (fMRI), during language and motor activation tasks. BOLD testing shows brain blood flow, and indirectly brain levels of activity by region. Five patients with extratemporal epilepsy associated with polymicrogyria were scanned in a 1.5 Tesla Siemens scanner with BOLD fMRI sequences, following language and motor paradigms. Functional images were processed using Brain Voyager software. Activation of polymicrogyric cortex in the brain area corresponding to the motor strip was present in all patients. Language studies revealed activation of polymicrogyric cortex over Broca´s area (the motor speech area) in three cases. Functionality was shown in polymicrogyric areas. Therefore, if surgical resection is indicated, careful functional planning is necessary due to functionality of polymicrogiric cortex. Epilepsia 2006;47(3).

Christian R. Baumann, Bernhard Schuknecht, Giorgio Lo Russo, Massimo Cossu, Alberto Citterio, Frederick Andermann, and Adrian M. Siegel

Considering the epileptogenic effect of cavernoma-surrounding hemosiderin, there are assumptions 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 whether seizure outcome after removal of cavernous malformations may be related to the extent of resection (removal) of surrounding hemosiderin-stained brain tissue. In this retrospective study, thirty-one consecutive patients with pharmacotherapy refractory epilepsy due to a cavernous malformation were included. In all patients, cavernoma were resected, and all patients underwent pre- and postoperative magnetic resonance imaging (MRI). We grouped patients according to MRI findings (hemosiderin completely removed vs. not/partially removed) and compared seizure outcome (as assessed by the Engel Outcome Classification score) between the two groups. Three years after resection of cavernoma, patients in whom hemosiderin-stained brain tissue had been removed completely had a better chance for a favorable long-term seizure outcome compared to those with detectable postoperative hemosiderin (p=0.037). Our study suggests that complete removal of cavernoma-surrounding hemosiderin-stained brain tissue may improve epileptic outcome after resection of cavernous malformations. Epilepsia 2006;47(3).

Theodore H. Schwartz, Lara Jeha, Adrianna Tanner, William Bingaman, and Michael R. Sperling

Epilepsy is a disease involving recurrent seizures. Surgery for medically intractable epilepsy is currently the most effective means of achieving seizure control. Although there are relatively few long-term outcome studies, evidence is mounting that the possibility of late seizure recurrence exists, even after an early seizure-free period We looked at the databases of two epilepsy surgery centers Patients eligible for study had a pre-operative MRI scans, were seizure free for one year after surgery, and had a minimal follow-up period of three years. The study included 285 patients, 254 with medial temporal lobe (MTLE) and 31 with neocortical epilepsy. The probability of having a single seizure after being seizure-free for one year was 18.3% at 5 years and 32.7% at 10 years However, only 13% were not seizure-free at the last follow-up  Predictors of late recurrences were the presence of pre-operative generalized tonic (GTC) seizures in patients with neocortical epilepsy and late age at surgery in patients with MTLE. Although the risk of at least one recurrent seizure after initially successful epilepsy surgery is relatively high, the rate of recurrent intractability is low The finding that late age at surgery and presence pre-operative GTCs are predictors of late recurrence indicates the importance of patient selection and early surgery for persistent seizure control. Epilepsia 2006;47(3).

Chang-Ho Yun, Sang Kun Lee, Seo Young Lee, Kwang Ki Kim, Sang Wook Jeong, and Chun-Ki Chung

Prediction of surgical success or failure in individual patient suffering from intractable epilepsy is important to identify the ideal surgical candidate. Therefore, we performed this study to identify favorable prognostic factors for neocortical epilepsy surgery. Surgical success was defined when patient was seizure-free at least two years after operation. Clinical features and the results of presurgical diagnostic tests were considered as probable prognostic factors. Statistical analyses were used to determine favorable prognostic factors. Among one hundred and ninety-three patients, surgical success was documented in 111 (57.5%) patients. We use multivariate analysis to identify favorable prognostic factors for neocortical epilepsy surgery. The presence of a focal lesion on MRI and correct localization of epileptogenic zone by PET or EEG were identified as predictors of a seizure-free outcome. Our results suggest that these findings may be of assistance in the selection of appropriate candidates for neocortical epilepsy surgery. Epilepsia 2006;47(3).

Christian Hoppe, Annkathrin Poepel, Robert Sassen, and Christian E. Elger

We evaluated the long-term outcome of medication reduction or discontinuation trials after epilepsy surgery in pediatric patients. Out of the total Bonn (Germany) pediatric surgical sample (1988-2001; n = 251), we were able to obtain postsurgical follow-up data for 232 patients. We surveyed 140 of these patients (or their parents, respectively) via a standardized telephone interview. Out of these patients, 102 completely discontinued medication; seven of them (7%) had recurring seizures that could be controlled by restarting the medication. Postsurgical auras or seizures before the trial, significantly increased the risk for recurring epileptic events after the trial. Nearly all patients with a complete discontinuation (n = 101) were completely seizure-free for at least three months prior to the survey. Two further surveyed patients lost postsurgical seizure freedom after medication reduction despite restarting their medication. From the records, we identified another nine patients with complete medication discontinuation and seven patients with medication reduction; two of these latter patients lost postsurgical seizure freedom despite restarting their medication. Taking together surveys and records, the rate of pediatric patients with postsurgical medication reduction or discontinuation trials was 55%. The seizure recurrence rate was 10% and the risk for a failure of restarted medication after recurring seizures was 3% of all trials. We conclude that the reduction or discontinuation of anticonvulsant medication after successful epilepsy surgery has a low risk of seizure recurrence for pediatric patients in long-term follow-up, particularly in cases of complete postsurgical seizure freedom before the trial. Epilepsia 2006;47(3).

February 2006
Extended, One-stage Callosal Section for Treatment of Refractory Secondary Generalized Epilepsy in Patients with Lennox-Gastaut and Lennox-like Syndrome
Arthur Cukiert, Jose Augusto Burattini, Pedro Paulo Mariani, Ródio Brandão Câmara, Lauro Seda, Cristine Mella Baldauf, Meire Argentoni, Carla Baise-Zung, Cássio Roberto Forster, and Valeria Antakli Mello

Epilepsy surgery is an accepted treatment modality for patients with refractory epilepsy. Usually these patients are evaluated by a multiprofessional team; and resective, disconnective and stimulatory procedures are used for seizure control. Although we would always prefer to offer resective procedures, which may ultimately render the patients seizure-free, some patients are not candidates for cortical resection and palliative procedures then might be considered. Callosal section, also known as callosotomy, is the most widely performed disconnective palliative procedure. With callosotomy, the large band of fibers connecting the two halves of the brain is severed. As a result, seizures cannot spread so rapidly through the brain. In this paper, we analyzed the effect of callosal section on 76 patients with the syndrome called Lennox-Gastaut and Lennox-like secondary generalized epilepsy These patients usually present with refractory epilepsy, including frequent drop attacks and developmental delay, and their treatment always represents a challenge. We were able to show that extensive callosal section could be safely obtained in a one-stage procedure by means of careful microsurgical techniques and that the clinical outcome regarding seizures was better than performing a small callosal section. Patients presented with an acute disconnection syndrome that lasted for two weeks; there was no other morbidity or mortality. Worthwhile improvement (>50%) was noted in 69 out of 76 patients; 52 patients had at least a 90% reduction in seizure frequency. Seven patients were seizure-free after surgery. The seizure patterns most responsive to surgery were atonic (92%), atypical absence (82%) and tonic-clonic (57%) seizures Parallel to the seizure frequency reduction, a consistent increase in attention level was observed postoperatively. Callosal section was found to be a good palliative option for these severely ill patients. It is the only procedure available so far that was capable of disrupting secondary bilateral synchrony, which is the electroencephalographic hallmark of these syndromes. Epilepsia 2006;47(2).

January 2006
Reduction of AEDs in Postsurgical Patients Who Attain Remission
Anne T. Berg, Barbara G. Vickrey, John T. Langitt, Michael R. Sperling, Shlomo Shinnar, Carl Bazil, Thaddeus Walczak, and Susan S. Spencer for the Multicenter Study of Epilepsy Surgery

There is little evidence to guide practice regarding the reduction of AEDs in individuals who achieve significant periods of seizure remission after resective surgery. We assessed the effect of reducing AEDs on relapse in post surgical patients who achieved at least a one year seizure-free remission We also examined potential predictors of relapse after AED reduction

Of 396 study subjects, 301 attained a one-year seizure-remission after surgery 129 reduced AEDs after achieving remission, and 162 did not reduce drugs Ten patients who stopped all AEDs before attaining remission were excluded from analysis In all, 114 (39%) patients relapsed: 73/162 (45%) in the non-reduction group and 41/129 (32%) in the reduction group (p=0.02) Compared with patients who did not reduce AEDs, patients who reduced drugs were more likely to have remitted immediately after hospital discharge (p<0.0001)  After adjustment for this factor, there was little or no apparent impact of drug reduction on the rate of relapse Within the 129 patients who reduced AEDs, only delayed remission after hospital discharge was significantly associated with an increased rate of relapse (RR=2.26, 95% CI=1.15, 4.48, p=0.02) Continued auras were marginally associated with relapse (RR=2.06, p=0.07).

Although many relapses in this cohort of post-surgical patients who achieved remission occurred in the context of reducing or completely eliminating AEDs, the risk was no higher than in those who continued AEDs . Randomized studies are needed to test the impact of drug reduction in seizure-free post-surgical patients. Epilepsia 2006;47(1).

November 2005
Victor Horsley’s Contribution to Jacksonian Epileptology
Mervyn J. Eadie

The pioneering English neurosurgeon Sir Victor Horsely (1857-1916), who was also a distinguished experimental physiologist, in his Brown Lectures of 1886, and in a lecture to the Cardiff Medical Society published in 1892, described studies investigating the propagation of epileptic seizure activity in experimental animals. His combination of strategically sited surgical lesions with cerebral cortex stimulation showed that, contrary to John Hughlings Jackson’s earlier belief, epileptic activity arising in one cerebral hemisphere had to spread to the opposite hemisphere via the corpus callosum and other inter-hemispheric connections before bilateral convulsing could occur. This knowledge caused Jackson by 1890 to modify his earlier views concerning the matter. Epilepsia 2005;46(11).

Jörg Wellmer, Guillen Fernández, Detlef B. Linke, Horst Urbach, Christian E. Elger, and Martin Kurthen

Cerebral language organization is highly variable among patients with focal epilepsy. In most patients, language functions are concentrated in the left hemisphere. In some patients, however, language functions are located in the right hemisphere, in others they are distributed bilaterally. Knowledge on individual language organization is of particular clinical interest in patients with intended epilepsy surgery. To estimate if in individual subjects resective surgery goes along with a risk for postsurgical language disturbance or memory deficits, epileptologists and neurosurgeons perform presurgical language lateralization. Traditionally, language lateralization is performed with the intracarotid amobarbital procedure (IAP, or Wada-test) during which the left and right hemisphere of the brain are successively anesthetized and the capability of the non-anesthetized hemisphere to support language function is tested. Yet, in times of modern imaging techniques, functional magnetic resonance imaging (fMRI) aims at completely replacing the IAP. This however, is not yet possible due to some technical limitation of fMRI. In the current study we show, that in most patients (over 80%, according to a large series of presurgical epilepsy patients) the IAP for language lateralization can be modified that way, that without loss of relevant information only the hemisphere of intended surgery is anesthetized and the second not. This reduces invasiveness for patients and costs for epilepsy centers. In times of non-invasive language lateralization, we propose unilateral IAP as the method of choice for the verification of doubtful fMRI results. Epilepsia 2005;46(11).

Robyn M. Busch, Thomas W. Frazier, Kathryn A. Haggerty, and Cynthia S. Kubu

In most individuals, the left temporal lobe of the brain is responsible for language functioning Confrontation naming measures, such as the Boston Naming Test (BNT), are often used to assess language functioning, because they are presumed to be sensitive to left temporal dysfunction As such, these measures are often used in the evaluation of surgical epilepsy patients Despite wide and frequent use, few studies have examined the utility of naming tasks in individuals with temporal lobe epilepsy (TLE) The current study examined the pre-surgical BNT performance of 217 right-handed adult patients with intractable TLE to determine the utility of this measure in predicting ultimate side of surgery The results support the clinical utility of the BNT in determining ultimate side of surgery and suggest that the BNT adds to the prediction over and above pre-surgical delayed memory and intelligence scores This relationship was found to be moderated by Full Scale IQ (FSIQ), age of seizure onset, and duration of epilepsy The prediction of left temporal surgery was best among patients with low BNT scores, high FSIQs, and late age of seizure onset In contrast, right temporal surgery was best predicted among patients with high BNT scores, low FSIQs, and short duration of epilepsy This study supports the clinical utility of the BNT in the pre-operative evaluation of candidates for TLE surgery and provides clinicians with a regression equation that can be used to predict side of surgery in patients with temporal lobe epilepsy. Epilepsia 2005;46(11).

October 2005
Reliable Registration of Preoperative MRI with Histopathology after Temporal Lobe Resections
Sofia H. Eriksson, Samantha L. Free, Maria Thom, William Harkness, Sanjay M. Sisodiya, and John S. Duncan

MRI (magnetic resonance imaging) can detect brain lesions that may be the cause of seizures in up to 80% of patients with refractory focal epilepsies. This is particularly important if epilepsy surgery is considered, since the outcome after surgery is more favorable in patients with a visible lesion. Newer MRI techniques can detect changes that are not identified on visual inspection of conventional MRI. The underlying causes for these changes are often unknown and correlation of preoperative MRI and pathology is important to clarify the causes if the newer techniques are to be of clinical use. Such correlations are far from straight-forward. We have developed a method to facilitate registration of preoperative MRI with the temporal lobe removed during epilepsy surgery to enable correlation of MRI findings with pathology. The lobes were removed in one piece that was then cut using a specially manufactured cutting-cradle that provided evenly thick (5 mm), parallel tissue-slices that could be matched with MRI-slices (approximately 1 mm thick). The MR images were sliced in the same orientation as the tissue-blocks using a computer program that allows rotation and re-slicing of images in any direction. When the tissue- and MRI-slices were matched by two observers individually, there was less than two mm difference between the matches in 15 of 16 cases (four mm in the remaining case) suggesting that the method was reliable. This technique can be applied to a range of MRI datasets, enabling exploration of the underlying causes of abnormalities seen on MRI scans. Epilepsia 2005;46(10).

September 2006
Hemispherectomy for Catastrophic Epilepsy in Infants
Jorge A. González-Martínez, Ajay Gupta, Prakash Kotagal, Deepak Lachhwani, Elaine Wyllie, Hans O. Lüders, and William E. Bingaman

The removal of one of the cerebral hemispheres (also called hemispherectomy) is performed successfully to treat medically intractable hemispheric epilepsy in adolescent and older children, providing remarkable results in terms of seizure control and quality of life. Nevertheless, experience and surgical indications in extremely young children are still unknown. In fact, the technical challenges of this drastic procedure, together with a reluctance to refer very young patients for “elective” surgery, often delays surgical treatment despite the need for earlier intervention Here, we report our single-surgeon experience with 18 children younger than two years-old who had hemispherectomy procedures to treat hemispheric life threatening epilepsy. In the end of the follow-up period, complications occurred in 16.7% with no death. Twelve out of 22 procedures (54.5%) resulted in incomplete disconnection (connected epileptic tissue left behind). Type of surgical procedure and bilateral electroencephalogram (EEG) abnormalities were not associated with persistent seizures after surgery. Incomplete disconnection was the only variable statistically associated with persistent seizures after surgery. In conclusion, hemispherectomy for seizure control provides excellent and dramatic results with a satisfactory complication rate. Our results support the concept that early surgery should be indicated in highly selected patients with severe, medically intractable and hemispheric epilepsy. Safety factors as an expert team in pediatric intensive care unit, neuro-anesthesia and an experience pediatric epilepsy neurosurgeon are mandatory. Epilepsia 2005;46(9).

Kelly A. McNally, A. LeBron Paige, George Varghese, Heping Zhang Edward J. Novotny, Jr., Susan S. Spencer, George Zubal, and Hal Blumenfeld

Epilepsy is a devastating illness with a major economic and psychosocial impact While medications are often beneficial, millions suffer from epileptic seizures that are not stopped by medications Hope for a cure can be offered to these patients through selective surgery to remove the region of seizure onset However, prior to surgery, the region of seizure onset must be identified with a high level of certainty. We have developed a new method of analyzing noninvasive brain images to identify the region of seizure onset The method, called ISAS (which stands for Ictal-interictal SPECT Analyzed by SPM) uses a statistical approach comparing blood flow changes in the brain of epilepsy patients to normal individuals Full technical details of the methods used for this study are provided at http://spect.yale.edu/ so that other centers can easily implement ISAS The method emphasizes the need to identify a single unambiguous region of seizure onset The analysis is based on objective measurement of blood flow changes during seizures, and eliminates much of the bias introduced by subjective readings of brain images by human eye We tested ISAS in a group of patients and found that when ISAS detected a single unambiguous region, it was always the correct location of seizure onset This was confirmed when epilepsy surgery at these locations cured the patients of their seizures We are hopeful that noninvasive brain imaging and improved analysis through ISAS can offer a cure for many patients with epilepsy Epilepsia 2005;46(9).

Rakesh K. Gupta, Sona Saksena, Atul Agarwal, Khader M. Hasan, Mazhar Husain, Vikas Gupta, and Ponnada A. Narayana

Epilepsy is common sequelae of traumatic brain injury (TBI). We present our experience with Diffusion tensor imaging (DTI), a relatively newer MRI technique in the differentiation of patients with chronic TBI with epilepsy from without epilepsy. The results of this study are based on the quantitative DTI data from twenty three chronic TBI patients who underwent DTI scans (with late post traumatic epilepsy n = 14, without epilepsy n = 9). Eleven healthy age matched controls were also scanned using the same protocol. Region-of-interest (ROI) analysis was performed within and beyond T2/fluid attenuating inversion recovery (FLAIR) visualized abnormality and the corresponding contralateral normal appearing region for determining the DTI derived metrics, fractional anisotropy (FA), mean diffusivity (MD). A significant reduction in regional mean FA ratio along with significant increase in regional mean MD ratio was observed in TBI patients as compared to controls. The mean regional FA ratio was significantly lower in TBI patients with epilepsy than in those without epilepsy. The tissue volume with low FA value was also found to be higher in TBI patients with epilepsy than without. Our results indicate that epileptogenesis in TBI is associated with more severe microstructural brain parenchymal damage as suggested by DTI. These findings may provide new insights into the pathophysiology of epilepsy and in planning specific surgical strategies related to post traumatic epilepsy (PTE) Epilepsia 2005;46(9).

August 2005
Status Gelasticus Following Temporal Lobectomy: Ictal FDG-PET Findings and the Question of Dual Pathology Involving Hypothalamic Hamartomas
Andre Palmini, Wim Van Paesschen, Patrick Dupont, Koen Van Laere, and Guido Van Drie

The ‘dogma’ that epilepsies originate only from the cerebral cortex, the outer region of the brain, has been recently shaken by the realization that a lesion deep in the brain, a hypothalamic hamartoma (HH), may generate seizures. A characteristi feature of HH-associated epilepsy are gelastic seizures, that is, sudden laughing attacks, which may pass unrecognized until other seizure types appear. The consensual establishment of a link between the finding of a HH and seizure origin from this lesion often neglects the possibility that an occasional patient may have some seizures originating from the deep HH and others from a given cortical region We describe a man with long-standing, yet unrecognized gelastic seizures, who later in his life started with other types of seizures, typically considered to originate in a specific cortical structure, namely, the left temporal lobe. He had a cyst in this region and EEG and functional imaging evidence pointing to that structure as responsible for these latter seizures. He underwent a resection of the left temporal lobe, and quite unexpectedly, in the post-operative period, began with recurrent laughing (gelastic) attacks, which lasted for long periods of time. Review of his brain images revealed the presence of a small HH, which had been overlooked. During a prolonged bout of laughing attacks it was possible to perform a positron emission tomography (PET) scan, which showed a very high metabolism in the HH. This case showed that it is possible to have both an epilepsy related to a HH and another type of epilepsy in the same patient. Epilepsia 2005;46(8).

Sang-Wuk Jeong, Sang Kun Lee, Keun-Sik Hong, Kwang-Ki Kim, Chun-Kee Chung, and Ho Kim

Temporal lobe epilepsy is a common neurologic disease that usually begins around adolescence. Many patients do not respond satisfactorily to current antiepileptic drugs and may be candidates to remove the seizure focus. What determines the long-term prognosis for control of temporal lobe epilepsy by surgery? Of the many studies of this question, most were limited by being a cross-sectional evaluation at one time after surgery (for example, at 1year or 3 years). This study was designed to analyze prognosis for 5 years as a whole after epilepsy surgery. Two hundred twenty-seven patients with temporal lobe epilepsy were included in this study. We performed various statistical analyses to identify prognostic factors. The seizure-free rate at 1year was 81.1%, with 75.2% at 5 years after surgery. The statistical analysis revealed that good outcome could be predicted by (a) younger age at surgery, (b) absence of secondarily generalized tonic-clonic seizures, and (c) hippocampal sclerosis on magnetic resonance image. Medial temporal lobe epilepsy might be a progressive disorder. Epilepsia 2005;46(8).

July 2005
The First Case of Invasive EEG Monitoring for the Surgical Treatment of Epilepsy: Historical Significance and Context
Antonio N. Almeida, Victor Martinez, and William Feindel

Controversy persists about when EEG became a fundamental tool in the pre-operative investigation for epilepsy surgery. This paper revisits Wilder Penfield’s first use of invasive EEG monitoring at the Montreal Neurological Institute, emphasizing its historical importance for the evolution of epilepsy surgery.

In April of 1939, Penfield made small holes on the skull over both temporal lobes in a patient with bilateral temporal epilepsy and placed electrodes on the dura, a tissue that covers the brain below the bone, intending to lateralize seizure origin. The patient underwent serial electroencephalograms using this technique. The final report of the recordings from epidural leads indicated a cortical lesion in the left temporal region. A skull X-ray taken after air injection in the spine, a common method to visualize the brain at that time, showed "the presence of diffuse cerebral atrophy, particularly in the left cerebral hemisphere.” Based on these congruent findings, the patient underwent surgery on April 21, revealing a cerebral scar in the posterior part of the left temporal lobe. Brain stimulation and electrocorticography delineated the extent of resection, while preserving the speech area. Unfortunately, seizures did not improve. Our paper shows that the concept of EEG-directed surgery was already present at the Montreal Neurological Institute in the late 1930’s. Epilepsia 2005;46(7).

June 2005
Periventricular White Matter Flumazenil Binding and Postoperative Outcome in Hippocampal Sclerosis
Alexander Hammers, Matthias J. Koepp, David J. Brooks, and John S. Duncan

In focal epilepsies, seizures originate in one part of the brain. Temporal lobe epilepsy (TLE) is the most common form, and often due to hippocampal sclerosis (HS), a scar in a part of the temporal lobe, usually visible on Magnetic Resonance Imaging (MRI). The majority of patients with HS will not become seizure free with medication. In selected patients, surgery (temporal lobectomy) offers a two thirds chance of becoming seizure free. Previously known reasons for surgical failure in the remaining third include hippocampal remnants, and evidence for bilateral seizure onset. Nerve cells (neurons; concentrated in the brain in grey matter) communicate chemically via neurotransmitter – neuroreceptor interactions. Positron Emission Tomography (PET) permits to quantify images of neuroreceptor binding. [11C]flumazenil PET shows decreased binding in epileptogenic grey matter. White matter (WM) is normally nearly devoid of neurons. Increased binding in the WM correlates with the number of heterotopic neurons, defined as neurons that have not correctly migrated to grey matter. We have previously shown such WM increases around the ventricles (fluid-filled cavities inside the brain) in epilepsy patients with normal MRI.

We hypothesized that HS patients who fail to become seizure free after surgery would show such increased binding, and restudied 15 patients. On the group level, increased binding around the ventricles could indeed be shown in the seven patients who did not become seizure-free, compared with the other eight. However, the individual’s risk of not becoming seizure-free cannot currently be accurately predicted. PET studies can help to further pinpoint reasons for surgical failures. Epilepsia 2005;46(6).

May 2005
Occipital Lobe Epilepsy: Clinical Characteristics, Surgical Outcome and Role of Diagnostic Modalitie
Sang Kun Lee, Seo Young Lee, Dong-Wuk Kim, Dong Soo Lee, and Chun-Kee Chung

Occipital lobe epilepsy is a relatively rare epilepsy syndrome in which seizures originate from the occipital lobe (posterior pole of brain). In order to assess the role of various diagnostic methods, to identify a specific factor indicating a good surgical outcome, and to characterize the clinical features of occipital lobe epilepsy, we studied 26 patients who were diagnosed as having this type of epilepsy and who underwent epilepsy surgery. Diagnoses were established by standard presurgical evaluation methods, which included MRI, FDG-PET, ictal SPECT, video-EEG monitoring, and intracranial EEG monitoring. After epilepsy surgery, patients were followed up for at least two years. Sixteen of the 26 became seizure-free after surgery, and another eight patients experienced a favorable outcome but were not seizure-free. Sixteen of the 26 patients experienced a type of visual phenomena, i.e., visual hallucination, visual illusion, blindness, or a field defect. Interictal EEG showed focal occipital abnormal spikes in 50%. MRI showed focal abnormality in 73%. FDG-PET demonstrated focal abnormal area in 44%. Ictal SPECT was performed in 19 patients, and showed focal increase of blood flow in 37%. EEG during seizures correctly localized abnormal waves in 69%. No significant relationship was found between the diagnostic accuracy of any modality and surgical outcome. The localizations of epileptogenic zones by these different diagnostic methods were complementary. The concordance of three or more modalities was significantly observed in seizure-free patients after surgery. Some specific visual phenomena indicated an occipital onset of seizure. Various diagnostic methods can be useful to diagnose this epilepsy, and a greater concordance between presurgical evaluation methods indicates a better surgical outcome. Epilepsia 2005;46(5).

April 2005
A Child with Epilepsy in Whom Multifocal VEP Facilitated the Objective Measurement of the Visual Field
Eiichi Yukawa, Yeong-Jin Kim, Kensuke Kawasaki, Futoshi Taketani, and Yoshiaki Hara

Perimetry is a method for testing fields of vision to rule out consticted visual perception or “holes” in the visual fields Perimetry is classified into kinetic (moving) and static (still) measurements These examination procedures are subjective methods, and the results are influenced by mental factors, such as the subject’s concentration and learning effects. Subjects have to fixate their gaze on a central spot, and attend to other stimuli appearing elsewhere, without moving their eyes. In children, reliable perimetry is sometimes difficult due to inadequate understanding of the examination and decreased concentration In particular, in children with temporal lobe or occipital lobe epilepsy, visual field defects sometimes develop after surgery to treat the epilepsy, and therefore, pre- and post-operative assessment of visual field defects is important. In this study, we investigated whether visual field defects can be objectively evaluated using a test called the visual evoked potential (VEP). The visual field shows a reversing black-white checkerboard pattern on a TV screen to the child. Brainwave EEG recordings are recorded and analyzed by a computer to pick out the signal in the back (occipital) part of the brain where vision is processed. How big that signal is, and how fast it gets there relates to how well the visual pathways function. We used a special type of VEP, called multifocal VEPs. First, to determine normal waves in the VEP, recording was performed in 21 healthy children. The peak latency and the amplitude were used for assessment. In a child with epilepsy in whom kinetic or static perimetry was impossible, VEP were recorded, and compared with the peak latency and amplitude in the healthy subjects. VEP in the child with epilepsy showed abnormal waves in the right half of the visual field, which corresponded to the region of abnormality seen in the child’s brain MRI. The objective evaluation of visual field defects using VEP may be useful in children with epilepsy in whom perimetry as a subjective examination is difficult. Epilepsia 2005;46(4).

Lorie Hamiwka, Prasanna Jayakar, Trevor Resnick, Glenn Morrison, John Ragheb, Patricia Dean, Catalina Dunoyer, and Michael Duchowny

A cortical brain malformation represents a non-malignant condition in which brain cells have ended up in the wrong location during prenatal or childhood formation of the brain Misplaced brain cells in malformations tend to be prone to seizures. Children with malformations of cortical development represent a significant proportion of pediatric epilepsy surgery candidates From a cohort of 40 children operated between 1980 and 1992 with malformation of cortical development, 38 were alive and had data 10 years after surgery Age at surgery ranged from 6 months to 18 years (mean = 9.6 years). Thirty six had partial seizures and 2 had infantile spasms; 20 were not associated with obvious brain structural abnormalities. Pathological diagnoses were cortical dysplasia (n=31) and developmental tumor (n=7). At 10 year follow-up, 15 (40%) were seizure-free, 10 (26%) had >90 % seizure reduction and 13 (34%) were improved or unchanged. Children seizure-free at two-year follow-up were likely to remain seizure-free. Ten-year seizure-freedom was 72% in children with developmental tumors and 32% in the cortical dysplasia group. Complete gross surgical removal was statistically significant for favorable outcome and no patient with an incomplete resection was seizure-free. Epilepsia 2005;46(4)