Surgical candidates in children with epileptic spasms can be selected without invasive monitoring: A report of 70 cases

OBJECTIVE

Prior surgical series in children with drug-resistant epileptic spasms have reported use of intracranial EEG monitoring in up to two-third of patients. We report outcome after epilepsy surgery for drug-resistant epileptic spasms in a cohort of children without the use of intracranial EEG monitoring in any of the patients.

METHODS

Medical records of all consecutive children aged 5 years or under who had epilepsy surgery for epileptic spasms at Cleveland Clinic between 2000 and 2018 were reviewed. Post-operative seizure outcome and predictors of prognosis of seizure outcome were analyzed.

RESULTS

Seventy children with active epileptic spasms underwent surgical resections during the study period. Mean age at seizure onset was 6.8 (+9.31) months and median age at surgery was 18.5 months. An epileptogenic lesion was identified on brain MRI in all patients; 17 (24%) had bilateral abnormalities. Etiologies included malformations of cortical development (58%), perinatal infarct/encephalomalacia (39%), and tumor (3%). None of the patients had intracranial EEG. Surgical procedures included hemispherectomy (44%), lobectomy/ lesionectomy (33%), and multilobar resections (23%). Twelve children needed repeat surgery; six (50%) became seizure free after the second surgery. At six months follow-up, 73% (51/70) were seizure-free since surgery. At a mean follow-up of 4.7 years, 60% (42/70) had Engel 1 outcome. In those with seizure recurrence, 17 (60%) reported improvement. Shorter epilepsy duration (p = 0.05) and lobar or sub-lobar epileptogenic lesions (p = 0.02) predicted favorable seizure outcome at 6 months after surgery. For long term outcome, patients with bilateral abnormalities on MRI (p = 0.001), and multilobar extent on MRI (p = 0.02) were at higher risk for recurrence.

SIGNIFICANCE

Children with drug-resistant epileptic spasms secondary to an epileptogenic lesion detected on MRI could be selected for epilepsy surgery without undergoing intracranial EEG monitoring. A surgical selection paradigm without intracranial monitoring may allow early surgery without the risks of invasive monitoring.

Investigation of networks underlying hyperkinetic seizures utilizing ictal SPECT

Objective

To study neural networks involved in hyperkinetic seizures (HKS) using ictal SPECT.

Methods

We retrospectively identified 18 patients with HKS evaluated at the Cleveland Clinic between 2005 and 2015 with video-EEG monitoring and ictal SPECT. Semiology was confirmed by the consensus of 2 epileptologists' independent reviews and classified as type 1, 2, or 3 HKS. SPECT data were analyzed by 2 independent physicians using a z score of 1.5. Ictal hyperperfusion patterns for each group were analyzed visually and with SPM. Spatial normalization to Montreal Neurological Institute space for each patient’s data was performed, followed by flipping of data from patients with left-sided ictal onset to the right side. Finally, an average z score map for each group was calculated.

Results

Visual analysis and SPM identified different patterns of ictal hyperperfusion in the 3 subtypes of HKS. Type 1 seizures showed hyperperfusion in a more anteriorly located network involving the anterior insula, orbitofrontal cortex, cingulate, and anterior perisylvian region and rostral midbrain. Type 2 seizures were associated with hyperperfusion in a more caudally located network involving the orbitofrontal cortex, cingulate (middle and posterior), basal ganglia, thalami, and cerebellum. Type 3 seizures showed a mixed pattern of SPECT hyperperfusion involving the temporal pole and anterior perisylvian region.

Conclusions

Each of the 3 different semiologic subtypes of HKS is associated with distinct patterns of hyperperfusion, providing further insight into the neural networks involved. This knowledge may inform placement of invasive EEG electrodes in patients with HKS semiology undergoing presurgical evaluation.

Continuous EEG Monitoring in Neonates: One Size Does Not Fit All

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Don’t Just Stand There: Do Something! The Case for Peri-Ictal Intervention

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Semiology of hypermotor (hyperkinetic) seizures

BACKGROUND

Hypermotor seizures (HMSs) consist of complex movements involving proximal segments of the limbs and trunk that appear violent and inappropriate for the situation.

METHODS

We analyzed hypermotor seizure videos in seizure-free patients (Engel class I) following resective epilepsy surgery. After completion of video analysis, we reviewed EEG and neuroimaging data.

RESULTS

Search of our epilepsy surgery database yielded 116 patients classified as having hypermotor seizures between 1996 and 2013. From this subset, 17/31 (55%) patients had been seizure-free for >6months (mean follow-up: 3.3years). Mean seizure duration was 35s (range: 6-91s), of which the HM phase lasted a mean of 22s (range: 3-53s). In 16 patients (95%), hypermotor activity was seen at or within 10s of clinical seizure onset. Type I semiology occurred in 6 patients, type II semiology in 10 patients, and 1 patient exhibited features of both. Type I and type II semiologies were noted in patients who had frontal lobe as well as extrafrontal resections. Nonversive head and body turning occurred in 10 patients (ranging from 90° to 270°) which was ipsilateral to the side of resection in all patients and seen both in frontal and extrafrontal resections. Six out of eleven patients with abnormal MRI and 4/6 patients with nonlesional MRI underwent invasive EEG evaluation. Eight patients (47%) had frontal lobe resection, 4/17 (23%) patients had temporal lobe resection, and one patient each had parietal lobe, insular, temporoparietooccipital, or motor sparing resection; 1 patient had functional hemispherectomy.

CONCLUSION

Hypermotor semiology typically occurs at or within 10s after seizure onset. Ipsilateral head/body turning appears to be of lateralizing value whereas asymmetry of limb movement was not lateralizing. Hypermotor semiology is most often seen in frontal lobe epilepsy but may occur in seizures arising from other locations.

Epilepsy surgery of the temporal lobe in pediatric population: a retrospective analysis

BACKGROUND

There is still some reluctance to refer pediatric patients for epilepsy surgery, despite evidence of success in retrospective series.

OBJECTIVE

To describe surgical experience and long-term outcome in pediatric temporal lobe epilepsy (TLE) at a single institution.

METHODS

Retrospective review of pediatric (<18-years-old) TLE patients who underwent surgery between November 1996 and December 2006 at Cleveland Clinic Epilepsy Center. Cox proportional hazard modeling was used to assess outcome predictors.

RESULTS

One hundred thirty pediatric patients met study criteria. Mean time between seizure onset and surgery was 6.3 years. Invasive evaluation was used in 32 patients (24.5%). Hippocampal sclerosis was present in 70 patients (53.8%), either alone or associated in dual pathology. The complication rate was 7%. The seizure-freedom rates at 1, 2, 5, and 12 years were 76%, 72%, 54%, and 41%, respectively (Kaplan-Meier). With the use of the Engel outcome classification, 98 (75.3%) patients were class I, 11 (8.5%) class II, 9 (7%) class III, and 12 (9.2%) were class IV at last follow-up. Only 4 (3.1%) patients underwent reoperations. Antiepileptic drugs (AEDs) were discontinued in 36 patients (28.3%) in a mean period of 18 months (SD ± 17 months; range, 6-102 months). Although left-sided resection, lower number of preoperative AED trials (≤ 4), and tumor pathology correlated with favorable seizure outcomes, extensive surgical resection remained the only significant outcome predictor after multivariate analysis (P = .007; HR = 0.13 [95% confidence interval 0.007-0.64]).

CONCLUSION

Careful selection of surgical candidates by multidisciplinary evaluations is required. Long-term seizure control is achieved successfully with acceptable low complication rates.

Reoperative Hemispherectomy for Intractable Epilepsy

BACKGROUND:

In patients with medically intractable epilepsy and diffuse unilateral hemispheric disease, functional or disconnective hemispherectomy is a widely accepted and successful treatment option. If recurrent seizures develop after disconnective hemispherectomy, management options become more complex and include conversion to anatomic hemispherectomy.

OBJECTIVE:

To present the outcomes of all patients undergoing reoperative hemispherectomy in 1 institution by 1 surgeon since 1998.

METHODS:

The medical records, operative reports, and imaging studies for 36 patients undergoing reoperative hemispherectomy for continuing medically intractable epilepsy from 1998 to 2011 at Cleveland Clinic were reviewed. Patient characteristics, cause of seizure, imaging findings, surgery-related complications, and long-term seizure outcomes were evaluated.

RESULTS:

Patients presented with a variety of seizure origins, including Rasmussen encephalitis, perinatal infarction, cortical dysplasia, and hemimegalencephaly. Overall, 19% of patients were seizure free after conversion to anatomic hemispherectomy, and 45% reported a decrease in seizure frequency by ≥ 90%. An additional 36% reported no improvement. Generalized ictal electroencephalography tended to confer a poorer prognosis, as did cortical dysplasia as the underlying diagnosis.

CONCLUSION:

The possibility that residual epileptogenic tissue in the operated hemisphere remains connected should be considered after failed functional hemispherectomy because our data suggest that improvement in seizure frequency is possible after reoperative hemispherectomy, although the chance of obtaining seizure freedom is relatively low. The decision to proceed with reoperative hemispherectomy should be made after proper discussion with the patient and family and informed consent is given.

Clinical evidence for the utility of movement compensation algorithm in magnetoencephalography: successful localization during focal seizure

A movement compensation (MC) algorithm may help to evaluate seizure focus in magnetoencephalography despite patient movement. We report a boy whose ictal MEG focus was localized to the same sublobar region before and after head turning when MC was applied, but which was erroneously localized to a different area without MC. This study provides the first clinical evidence for utility of MC in magnetoencephalography for localizing focal seizures.

Imag(in)ing seizure propagation: MEG-guided interpretation of epileptic activity from a deep source

Identification and accurate localization of seizure foci is vital in patients with medically-intractable focal epilepsy, who may be candidates for potentially curative resective epilepsy surgery. We present a patient with difficult-to-control seizures associated with an occult focal cortical dysplasia residing within the deeper left parietal operculum and underlying posterior insula, which was not detected by conventional MRI analysis. Propagated activities from this deeper generator produced misleading EEG patterns both on surface and subdural electrode recordings suggesting initial activation of the perirolandic and mesial frontal regions. However, careful spatio-temporal analysis of stereotyped interictal activities recorded during MEG, using sequential dipole modeling, revealed a consistent pattern of epileptic propagation originating from the deeper source and propagating within few milliseconds to the dorsal convexity. In this instance, careful dissection of noninvasive investigations (interictal MEG along with ictal SPECT findings) allowed clinicians to dismiss the inaccurate and misleading findings of the traditional "gold-standard" intracranial EEG. In fact, this multimodal noninvasive approach uncovered a subtle dysplastic lesion, resection of which rendered the patient seizure-free. This case highlights the potential benefits of dynamic analysis of interictal MEG in the appropriate clinical context. Pathways of interictal spike propagation may help elucidate essential neural networks underlying focal epilepsy.

Outcome of no resection after long-term subdural electroencephalography evaluation in children with epilepsy

OBJECT

The aim of this study was to identify the reasons for and predictors of no resection of the epileptogenic zone in children with epilepsy who had undergone long-term invasive subdural grid electroencephalography (SDG-EEG) evaluation.

METHODS

The authors retrospectively reviewed the consecutive medical records of children (< 19 years of age) who had undergone SDG-EEG evaluation over a 7-year period (1997-2004). To determine the predictors of no resection, the authors obtained the clinical characteristics and imaging and EEG findings of children who had no resection after long-term invasive SDG-EEG evaluation and compared these data with those in a group of children who did undergo resection. They describe the indications for SDG-EEG evaluation and the reasons for no resection in these patients.

RESULTS

Of 66 children who underwent SDG-EEG evaluation, 9 (13.6%) did not undergo subsequent resection (no-resection group; 6 males). Of these 9 patients, 6 (66.7%) had normal neurological examinations and 5 (55.6%) had normal findings on brain MR imaging. Scalp video EEG localized epilepsy to the left hemisphere in 6 of the 9 patients and to the right hemisphere in 2; it was nonlocalizable in 1 of the 9 patients. Indications for SDG-EEG in the no-resection group were ictal onset zone (IOZ) localization (9 of 9 patients), motor cortex localization (5 of 9 patients), and language area localization (4 of 9 patients). Reasons for no resection after SDG-EEG evaluation were the lack of a well-defined IOZ in 5 of 9 patients (4 multifocal IOZs and 1 nonlocalizable IOZ) and anticipated new permanent postoperative neurological deficits in 7 of 9 patients (3 motor, 2 language, and 2 motor and language deficits). Comparison with the resection group (57 patients) demonstrated that postictal Todd paralysis in the dominant hand was the only variable seen more commonly (χ(2) = 4.781, p = 0.029) in the no-resection group (2 [22.2%] of 9 vs 2 [3.5%] of 57 patients). The no-resection group had a larger number of SDG electrode contacts (mean 126. 5 ± 26.98) as compared with the resection group (100.56 ± 25.52; p = 0.010). There were no significant differences in the demographic data, seizure characteristics, scalp and invasive EEG findings, and imaging variables between the resection and no-resection groups.

CONCLUSIONS

Children who did not undergo resection of the epileptogenic zone after SDG-EEG evaluation were likely to have normal neurological examinations without preexisting neurological deficits, a high probability of a new unacceptable permanent neurological deficit following resection, or multifocal or nonlocalizable IOZs. In comparison with the group that underwent resection after SDG-EEG, a history of Todd paralysis in the dominant hand and arm was the only predictor of no resection following SDG-EEG evaluation. Data in this study will help to better select pediatric patients for SDG-EEG and to counsel families prior to epilepsy surgery.

Neurostimulation: vagus nerve stimulation and beyond

Patients with medically intractable epilepsy who are not candidates for epilepsy surgery could benefit from neurostimulation. At this time, vagus nerve stimulation (VNS) therapy is the only Food and Drug Administation-approved neurostimulation modality; it has been shown to be efficacious and just as well tolerated in children and adolescents as in adults. Notwithstanding the initial cost of the device and implantation, VNS therapy has been shown to be a cost-effective treatment, reducing direct medical costs and improving health-related quality of life measures. Deep brain stimulation of various brain regions, especially the anterior nucleus of the thalamus and responsive neurostimulation, also appear effective but are not yet approved for clinical use. Repetitive transcranial magnetic stimulation, which is also in early clinical development, is promising and could become available in the not too distant future.

Epilepsy in the setting of neurocutaneous syndromes

The neurocutaneous syndromes are characterized by congenital dysplastic abnormalities involving the skin and nervous system. The commonest neurocutaneous syndromes manifesting epilepsy are tuberous sclerosis and the Sturge-Weber syndrome. Neurofibromatosis and other lesser-known entities, such as epidermal nevus syndrome, are also known to be accompanied by epilepsy. These syndromes are not related to one another. This article reviews what has been learned about the epileptic syndromes in these disorders.

Surgery for catastrophic epilepsy in infants 6 months of age and younger

OBJECT

Few data are available concerning efficacy and safety of surgery for catastrophic epilepsy in the first 6 months of life.

METHODS

The authors retrospectively analyzed epilepsy surgeries in 15 infants ranging in age from 1.5 to 6 months (median 4 months) and weight from 4 to 10 kg (median 7 kg) who underwent anatomical (4 patients) or functional (7 patients) hemispherectomy, or frontal (1 patient), frontoparietal (2 patients), or parietooccipital (1 patient) resection for life-threatening catastrophic epilepsy due to malformation of cortical development.

RESULTS

No patient died. Intraoperative complications included an acute ischemic infarction with hemiparesis in our youngest, smallest infant. The most frequent complication was blood loss requiring transfusion, which was encountered in every case. The estimated blood loss was 3-214% (median 63%) of the total blood volume. At maximum follow-up of 6-121 months (median 60 months), 46% were seizure free.

CONCLUSIONS

Epilepsy surgery may be effective in young infants as it is in older children. However, intraoperative blood loss and risk of permanent postoperative neurological deficits present significant challenges.

Contralateral MRI abnormalities in candidates for hemispherectomy for refractory epilepsy

PURPOSE

To assess the impact of contralateral magnetic resonance imaging (MRI) findings on seizure outcome after hemispherectomy for refractory epilepsy.

METHODS

We retrospectively reviewed 110 children, 0.4-18 (median 5.9) years of age, who underwent hemispherectomy for severe refractory epilepsy at Cleveland Clinic Children's Hospital. In children with contralateral (as well as ipsilateral) MRI findings appreciated preoperatively, the decision to proceed to surgery was based on other features concordant with the side with the most severe MRI abnormality, including ipsilateral epileptiform discharges, lateralizing seizure semiology, and side of hemiparesis.

RESULTS

We retrospectively observed contralateral MRI abnormalities (predominantly small hemisphere, white matter loss or abnormal signal, or sulcation abnormalities) in 81 patients (74%), including 31 of 43 (72%) with malformations of cortical development (MCD), 31 of 42 (73%) with perinatal injury from infarction or hypoxia, and 15 of 25 (60%) with Rasmussen's encephalitis, Sturge-Weber syndrome, or posttraumatic encephalomalacia. Among 84 children (76%) with lesions that were congenital or acquired pre- or perinatally, 67 (83%) had contralateral MRI abnormalities (p = 0.02). Contralateral findings were subjectively judged to be mild or moderate in 70 (86%). At follow-up 12-84 (median 24) months after surgery, 79% of patients with contralateral MRI abnormalities were seizure-free compared to 83% of patients without contralateral MRI findings, with no differences based on etiology group or type or severity of contralateral MRI abnormality.

DISCUSSION

MRI abnormalities, usually mild to moderate in severity, were seen in the contralateral hemisphere in the majority of children who underwent hemispherectomy for refractory epilepsy due to various etiologies, especially those that were congenital or early acquired. The contralateral MRI findings, always much less prominent than those in the ipsilateral hemisphere, did not correlate with seizure outcome and may not contraindicate hemispherectomy in otherwise favorable candidates.

Language assessment in Wada test: comparison of methohexital and amobarbital

INTRODUCTION

Methohexital has replaced amobarbital during Wada testing at many centers. The objective of our study was to compare the use of methohexital and amobarbital during Wada testing regarding language and memory lateralization quotients as well as speech arrest times.

METHODS

A chart review of 582 consecutive patients undergoing 1041 Wada-procedures was performed (left=60, right=63, bilateral=459). Language lateralization was calculated based on duration of speech arrest using a laterality index, defined as (L-R)/(L+R). Memory lateralization was expressed as percentage of retained objects and laterality quotient.

RESULTS

Language and memory lateralization revealed a similar distribution with amobarbital and methohexital. Speech arrest after left and right-sided injection was significantly longer in the amobarbital group as compared to the methohexital group. Language lateralization did not differ in the two groups. Percentage of retained memory items was higher in the methohexital group and there were fewer presented test items in the methohexital group.

DISCUSSION

Language and memory testing during the Wada test can successfully be performed with methohexital instead of amobarbital. The shorter half-life of methohexital allows repeated injections and shorter interhemispheric testing intervals, but also shortens the testing window.

Epilepsy surgery in children with electrical status epilepticus in sleep

OBJECTIVE

Pediatric epilepsy surgery candidates with unilateral congenital or early-acquired brain lesions may present with refractory seizures and generalized electroencephalographic features such as electrical status epilepticus in sleep (ESES). The purpose of our study was to review the clinical presentation, neuroimaging findings, and outcome in a series of children with unilateral brain lesions and ESES undergoing resective surgery for refractory epilepsy.

METHODS

A total of 415 consecutive patients younger than 18 years of age undergoing video electroencephalographic evaluation and epilepsy surgery at Cleveland Clinic were reviewed for ESES, an underlying pathological lesion, and outcome after surgery.

RESULTS

Eight patients were included. All patients presented with medically refractory epilepsy, hemiparesis, and developmental delay. The pathogenesis was perinatal infarction in 7 patients and malformation of cortical development in 1 patient. Preoperative electroencephalography demonstrated generalized interictal spikes, electroencephalographic seizures, and ESES in all cases. Age at the time of surgery ranged from 3 to 14 years. Six patients underwent hemispherectomy, and 2 patients underwent focal resection. Six patients became seizure-free after resection. Two patients with functional hemispherectomy continued to have rare seizures, but were much improved. These patients also had perinatal infarctions in the hemisphere contralateral to the resection, possibly indicating a less beneficial outcome. Postoperative electroencephalography demonstrated resolution of generalized interictal discharges and ESES in all. Formal pre- and postoperative neuropsychological testing showed overall improvement of age-equivalent scores.

CONCLUSION

Children with unilateral brain lesions and seizures may become seizure-free after epilepsy surgery, even if the preoperative electroencephalogram shows generalized ESES. The lesion occurring early in life and the location of the lesion may play a role in the development of ESES. Cognitive impairment may be aggravated by the persistence of ESES. Preliminary developmental data in this small sample suggest that termination of seizures and possibly of ESES by epilepsy surgery may have developmental benefits.

Classification

In this article, we review the practical approach and diagnostic relevance of current seizure and epilepsy classification concepts and principles as a basic framework for good management of patients with epileptic seizures and epilepsy. Inaccurate generalizations about terminology, diagnosis, and treatment may be the single most important factor, next to an inadequately obtained history, that determines the misdiagnosis and mismanagement of patients with epilepsy. A stepwise signs and symptoms approach for diagnosis, evaluation, and management along the guidelines of the International League Against Epilepsy and definitions of epileptic seizures and epilepsy syndromes offers a state-of-the-art clinical approach to managing patients with epilepsy.

The relationship between sleep and epilepsy

The occurrence of seizures in the sleep state is observed in nearly one third of patients. This is caused by an intimate relationship between the physiological state of sleep and the pathological process underlying epileptic seizures. Both sleep and sleep deprivation influence the frequency of epileptiform discharges on electroencephalograms as well as the occurrence of clinical seizures, typically during nonrapid eye movement sleep. The relationship of epileptiform activity to nonrapid eye movement sleep is vividly shown in the syndrome of continuous spikes in slow-wave sleep and the Landau-Kleffner syndrome. Seizure semiology can also be influenced by sleep and sleep deprivation. Sleep disorders may influence seizure control, and effective treatment of sleep disorders can improve seizure control. Seizures, antiepileptic drugs, ketogenic diet, and vagus nerve stimulation all influence sleep quality, daytime alertness, and neurocognitive function.

Discontinuation of medications after successful epilepsy surgery in children

To evaluate the need for antiepileptic drugs after successful epilepsy surgery in pediatric patients, we retrospectively reviewed patients who had epilepsy surgery and were seizure free or had rare nondisabling auras during the first 6 postoperative months. Association between drug discontinuation and seizure recurrence was evaluated using Cox proportional hazards multivariable survival analysis. Medications were withdrawn in 68 of 97 patients, seizure free (or with rare nondisabling auras) for >6 months after surgery; 57 of the 68 (84%) remained seizure free; the other 11 (16%) had seizure recurrence after 68 months (median). Seizure recurrence was controlled with medication in 7 of the 11 patients (3 have rare seizures, 1 frequent auras). Discontinuing medications at <6 mo, compared with later or no withdrawal, had significant risk for seizure recurrence (hazard ratio 5.8; 95% confidence interval 1.8, 17.5; P = 0.003). Of 29 patients who continued drugs, 28 (97%) remained seizure free after 37 months (median). Freedom from seizures 6 months after surgery predicted good outcome (95% seizure free, with or without medication). If discontinuation is offered after 6 months, the majority of patients (84%) can be expected to remain seizure free with no further need for medication. Although seizure breakthrough is possible in a smaller percentage, restarting drugs is likely to restore seizure control.

Metabolic testing in the pediatric epilepsy unit

Unexplained mental retardation is noted in up to 3% of the general population, and upwards of 30% of these patients manifest epilepsy. There is no standardized approach to metabolic testing in these patients. In a first step toward a standardized approach for our center, we performed a retrospective evaluation of testing of our patients in the past. Records of 429 children admitted to our pediatric epilepsy-monitoring center in 2005 were reviewed. We noted whether they had developmental delay, their type of epilepsy, and the extent of metabolic testing. Ninety percent of our patients had developmental delay, and 20% received some form of metabolic testing. Abnormal results suggesting mitochondrial dysfunction were found in 28% of our patients without a previous underlying diagnosis. Metabolic abnormalities were found in 75% of those with multifocal interictal discharges. Secondary carnitine deficiency was identified in 22%; these patients were taking valproic acid. Primary or secondary metabolic abnormalities likely represent a prominent finding in these patients. Differential diagnoses involving mitochondrial dysfunction should receive serious consideration. Findings such as carnitine deficiency can be identified and treated. A systematic approach for such testing is needed. A prospective evaluation at our institution is planned.

Subdural electrode analysis in focal cortical dysplasia: predictors of surgical outcome

OBJECTIVE

Patients undergoing epilepsy surgery for focal cortical dysplasia (FCD) guided by subdural EEG generally have a poor surgical outcome. Our objective was to identify predictors of postoperative seizure recurrence in this patient cohort.

METHODS

We retrospectively reviewed 48 consecutive surgeries guided by subdural electrode recordings between 1990 and 2004 in patients with a pathologic diagnosis of isolated FCD. Using survival analysis, we analyzed results of the noninvasive evaluation, MRI, subdural interictal and ictal EEG patterns, extent of resection, proximity to eloquent cortex, and postoperative EEG.

RESULTS

After a median follow-up of 2.7 years, 45% of patients were completely seizure-free. Most seizures recurred in the first 6 months or between years 2 and 3 after surgery. On univariate analysis, seizure recurrence was associated with bilateral EEG abnormalities, multiple semiologic seizure types, and incomplete resection of the ictal onset zone. The absence of an MRI lesion did not affect outcome, nor did proximity to eloquent cortex. Interictal paroxysmal fast and runs of repetitive spikes correlated with the ictal onset zone, whereas isolated spikes did not. The 6-month EEG predicted ultimate surgical failure in patients seizure-free at that stage. An ictal spread pattern from the edge of the subdural grids was an independent predictor of seizure recurrence on multivariate analysis.

CONCLUSIONS

We have identified specific predictive factors that may guide the surgical evaluation of patients with focal cortical dysplasia and intractable epilepsy requiring subdural EEG monitoring. Successful surgical results can be obtained utilizing subdural EEG in carefully selected patients.

Multiple auras: Clinical significance and pathophysiology

BACKGROUND

Patients with partial epilepsy may report multiple types of aura during their seizures. The significance of the occurrence of multiple auras in the same patient is not known.

METHODS

The clinical and electrophysiologic characteristics of patients with more than one aura type (abdominal, auditory, autonomic, gustatory, olfactory, psychic, somatosensory, and visual auras), evaluated in the Cleveland Clinic epilepsy monitoring unit between 1989 and 2005, were studied.

RESULTS

Thirty-one patients experienced multiple aura types during a seizure. Ninety percent of patients with at least two aura types (n = 31) and 100% percent of patients with at least three aura types (n = 12) had seizures arising from the right/nondominant hemisphere. EEG seizures remained restricted in all patients during their auras. nineteen [corrected] patients had epilepsy surgery with seizure freedom in 53%. Subdural EEG recordings in six patients showed either a march of sequential auras, or in one case, several ictal onset zones resulting in separate isolated auras. Ictal SPECT in six patients with right-sided seizures showed a lack of activation in brainstem structures.

CONCLUSIONS

Most patients who report multiple aura types have localized epilepsy in the nondominant hemisphere, and are good surgical candidates. A common mechanism for multiple auras may be a spreading but restricted EEG seizure activating sequential symptomatogenic zones, but without the ictal activation of deeper structures or contralateral spread to cause loss of awareness and amnesia for the auras.

Epilepsy surgery in an 8-year-old boy with intractable seizures

Mark is an 8-year-old boy with a history of intractable epilepsy. Mark's seizures started when he was five years old, lasting less than a minute, with 7-10 episodes occurring in succession. Daytime seizures were described by his parents a "staring events where he does not respond, he will pick at clothes and speak gibberish." He was often disorientated for the remainder of the day. Nighttime seizures were described as "sitting up straight in bed, staring at the ceiling, and being unresponsive." An increase in his seizure frequency after multiple anticonvulsant medications prompted a surgical evaluation. A magnetic resonance (MR) brain scan indicated mild encephalomacia in the left hemisphere. A video electroencephalogram (EEG) demonstrated that the seizures initiated from the left hemisphere in association with multiple subclinical seizures. A PET scan showed decreased uptake in the left frontal lobe compared to the right. At 7 years of age Mark underwent a left frontal temporal-parietal resection. He had a post-surgical infection, but no other medical sequelae. After surgery, there was a significant decrease in seizures with only one seizure in the 2 month post operative period. Mark had neuropsychological testing prior to and following surgery. Pre-surgical results indicated that his IQ was within the low-average range. Visual-perceptual abilities, motor tasks and attention domains indicated difficulties. Post-surgical neuropsychological evaluation revealed a positive outcome. IQ remained in the low average range and there was a mild improvement in visual-perceptual/visual-constructional areas. Academic skills were unchanged with the exception of a slight decline in reading ability. Attention scores improved although redirection was required to sustain his attention during tasks. An increase in non-compliant behavior and emotional liability was noted by his parents.At the time of referral, when Mark was 8-years 3-months old, parental concerns included inattention, anger and emotional lability. The referral question posed was: "Does Mark's inattention represent an attention deficit/hyperactivity disorder, anxiety, or other psychological problems and what is the relationship of his current behaviors to his epilepsy?"

Successful surgery for epilepsy due to early brain lesions despite generalized EEG findings

OBJECTIVE

To understand the role of epilepsy surgery in children with generalized or bilateral findings on preoperative scalp EEG.

METHODS

From our pediatric epilepsy surgery series, we identified 50 patients in whom 30 to 100% of preoperative epileptiform discharges (ictal, interictal, or both) were generalized or contralateral to the side of surgery.

RESULTS

All patients had severe refractory epilepsy and an epileptogenic lesion on brain MRI. Ninety percent of the lesions were congenital, perinatal, or acquired during infancy, predominantly malformations of cortical development (44%) or cystic encephalomalacia (40%). Age at surgery was 0.2 to 24 (median 7.7) years. Surgeries were hemispherectomy (64%) or lobar or multilobar resection. At last follow-up (median 24.0 months), 72% of patients were seizure-free, 16% had marked improvement with only brief episodes of staring or tonic stiffening, and 12% were not improved. The rate of seizure-free outcome was not significantly associated with age at seizure onset or surgery, presence of hemiparesis or focal clinical features during seizures, type of lesion, or surgery type. Postoperative seizure-free rate did not differ from that in a comparison group of similar patients who matched the study group except for their high percentage (70 to 100%) of ipsilateral ictal and interictal epileptiform discharges on preoperative EEG.

CONCLUSIONS

Epilepsy surgery may be successful for selected children and adolescents with a congenital or early-acquired brain lesion, despite abundant generalized or bilateral epileptiform discharges on EEG. The diffuse EEG expression may be due to an interaction between the early lesion and the developing brain.

Pediatric epilepsy surgery in focal lesions and generalized electroencephalogram abnormalities

Generalized abnormalities on scalp electroencephalograms (EEG) are not uncommon in children with partial epilepsy in whom a dominant focus of interictal and ictal abnormalities concordant to the brain lesion usually clarifies surgical candidacy. Children with exclusively generalized or multiregional EEG abnormalities and mental retardation are usually not considered surgical candidates, even when brain lesions are seen on imaging. Of 176 pediatric epilepsy surgeries at our center, we describe 10 children with exclusively generalized and multiregional interictal and ictal EEG abnormalities who had resection of a focal lesion seen on brain MRI. Surgical decisions were strengthened by clinical data. Surgery was offered as a last resort because of catastrophic epilepsy and treatment failures. At 26 months' mean postoperative follow-up, eight had no seizures, and two had infrequent seizures. Six months after surgery, generalized electroencephalographic abnormalities had resolved in all. We conclude that generalized and multiregional EEG abnormalities in the absence of dominant focus may not preclude epilepsy surgery in children with a congenital or acquired lesion seen on MRI. Generalized EEG abnormalities are likely secondary phenomena that resolve after surgery. Maladaptive neural plasticity and secondary epileptogenesis are potential mechanisms that mask an epileptogenic lesion with generalized EEG abnormalities.

Developmental outcome after epilepsy surgery in infancy

OBJECTIVES

Our goals were to determine the effect of epilepsy surgery in infants (<3 years of age) on development and describe factors associated with postoperative developmental outcome.

METHODS

We identified 50 infants among 251 consecutive pediatric patients (<18 years old) undergoing epilepsy surgery. Charts were reviewed for clinical data and neurodevelopmental testing with the Bayley Scales of Infant Development. A developmental quotient was calculated to compare scores of children at different ages.

RESULTS

Complete data were available on 24 of 50 infants. Surgeries included 14 hemispherectomies and 10 focal resections. Seventeen patients became seizure free; 5 patients had >90% seizure reduction, 1 had >50% seizure reduction, and 1 had no change. The developmental quotient indicated modest postoperative improvement of mental age. The preoperative and postoperative development quotients correlated well. Younger infants had a higher increase in developmental quotient after surgery. Patients with epileptic spasms were younger and had a lower developmental quotient at presentation, but increase in developmental quotient was higher in this subgroup.

CONCLUSIONS

After surgery, seizure frequency and developmental quotient improved. Developmental status before surgery predicted developmental function after surgery. Patients who were operated on at younger age and with epileptic spasms showed the largest increase in developmental quotient after surgery.

Long-term results with vagus nerve stimulation in children with pharmacoresistant epilepsy

PURPOSE

To retrospectively review our experience with VNS in pediatric patients with pharmacoresistant epilepsy and examine the seizure-frequency outcome and rates of discontinuation in two age groups: adolescent and pre-adolescent children.

RESULTS

Complete pre- and post-VNS data were available for 46/49 patients. Median age at implantation was 12.1 (range 2.3-17.9) and median duration of epilepsy 8.0 (1.9-16.9) years. Twenty-one patients (45.6%) were under 12 years at the time of surgery. Median follow-up was 2 years; follow-up exceeded 4 years in 9/46 patients. As compared to baseline, median seizure-frequency reduction in the setting of declining numbers was 56% at 3 months, 50% at 6, 63% at 12, 83% at 24 and 74% at 36 months. When a last observation carried forward analysis was employed median seizure-frequency reduction in the range of 60% was observed at 1, 2 and 3 years post-VNS. Twenty patients (43.5%) had >75% seizure-frequency reduction. No response (increase or <50% reduction) was observed in 19/46 (41.3%). Five patients (10.1%) were seizure-free for more than 6 months by their last follow-up. There was no difference in the number of AEDs used before and after VNS. The long-term discontinuation rate was 21.7% and reflected a lack of clinical response or infection.

CONCLUSIONS

In this series VNS was well-tolerated and effective as add-on therapy for refractory seizures in children of all ages. Response was even more favorable in the younger group (<12 years at implantation). Infection and lack of efficacy were the most common reasons for discontinuation of long-term VNS therapy in this group.

Temporal lobe epilepsy in children: overview of clinical semiology

Temporal lobe epilepsy in children has been less well studied compared to that seen in adults. Whereas hippocampal sclerosis is the most common etiology for the adult temporal lobe epilepsy syndromes, tumors and malformations of cortical development are more commonly seen in children. Differences in seizure semiology are also apparent. Temporal lobe epilepsy in very young infants may exhibit prominent motor manifestations reminiscent of extra-temporal seizures. These motor manifestations however decrease with increasing age and are less abundant in adults. Automatisms, which are commonly seen in temporal lobe epilepsy in all age groups, are simple at a younger age and become increasingly more complex and discrete with age. Several case studies, illustrated on the video are included in this review. They highlight the differences in temporal lobe seizure semiology between children and adults. [Published with video sequences].

Focal semiologic and electroencephalographic features in patients with juvenile myoclonic epilepsy

PURPOSE

A few reports have described focal electroencephalographic or clinical features or both of juvenile myoclonic epilepsy (JME), but without video-EEG documentation. We examined focal clinical and EEG features in patients with JME who underwent video-EEG monitoring.

METHODS

Twenty-six patients (nine males and 17 females) who had seizures recorded during video-EEG monitoring were included. Age at seizure onset was 0 to 22 years (mean, 12.3 years), and age at monitoring was 12 to 44 years (mean, 26.5 years). In one patient with left parietooccipital epilepsy, primary generalized tonic-clonic seizures developed after resection of the parietal tumor. Two patients had both temporal lobe epilepsy and JME. Videotaped seizures in each patient were analyzed. Interictal and ictal EEG also were analyzed for any focal features.

RESULTS

Focal semiologic features were observed in 12 (46%) of 26 patients. Six patients had focal myoclonic seizures, and two had Figure 4 sign: one with version to the left, and another had left version followed by Figure 4 sign, and left arm clonic seizure. Their ictal EEGs were generalized at onset but with a lateralized evolution over the right hemisphere. The patient who had both JME and left parietooccipital epilepsy, right arm clonic seizure, and Figure 4 sign was seen during a generalized EEG seizure. Interictally, one patient had temporal sharp waves, and another had run of spikes in the right frontal region.

CONCLUSIONS

Fourteen (54%) of 26 patients with JME exhibited focal semiologic or electroencephalographic features or both. Video-EEG was essential in reaching a correct diagnosis and choosing an appropriate antiepileptic drug regimen.

Hemispherectomy for catastrophic epilepsy in infants

PURPOSE

To report our experience with hemispherectomy in the treatment of catastrophic epilepsy in children younger than 2 years.

METHODS

In a single-surgeon series, we performed a retrospective analysis of 18 patients with refractory epilepsy undergoing hemispherectomy (22 procedures). Three different surgical techniques were performed: anatomic hemispherectomy, functional hemispherectomy, and modified anatomic hemispherectomy. Pre- and postoperative evaluations included extensive video-EEG monitoring, magnetic resonance imaging, and positron emission tomography scanning. Seizure outcome was correlated with possible variables associated with persistent postoperative seizures. The Generalized Estimation Equation (GEE) and the Barnard's exact test were used as statistical methods.

RESULTS

The follow-up was 12-74 months (mean, 34.8 months). Mean weight was 9.3 kg (6-12.3 kg). The population age was 3-22 months (mean, 11.7 months). Thirteen (66%) patients were seizure free, and four patients had >90% reduction of the seizure frequency and intensity. The overall complication rate was 16.7%. No deaths occurred. Twelve (54.5%) of 22 procedures resulted in incomplete disconnection, evidenced on postoperative images. Type of surgical procedure, diagnosis categories, persistence of insular cortex, and bilateral interictal epileptiform activity were not associated with persistent seizures after surgery. Incomplete disconnection was the only variable statistically associated with persistent seizures after surgery (p<0.05).

CONCLUSIONS

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 catastrophic epilepsy. Safety factors such as an expert team in the pediatric intensive care unit, neuroanesthesia, and a pediatric epilepsy surgeon familiar with the procedure are mandatory.

Electro-clinical and imaging characteristics of focal cortical dysplasia: Correlation with pathological subtypes

INTRODUCTION

Focal cortical dysplasia (CD) is a common cause of pharmaco-resistant epilepsy. CD is due to abnormalities in neuronal migration, proliferation, and/or differentiation that result in four distinct pathological subtypes: 1A, 1B, 2A, and 2B. In order to provide clinical correlation to these pathological subtypes, we reviewed the electro-clinical and imaging characteristics and surgical outcomes of the four pathological subtypes of CD.

METHODS

We retrospectively reviewed patient data from epilepsy surgeries at the Cleveland Clinic Foundation between 1990 and 2002. Only those patients with the definite pathological diagnosis of isolated cortical dysplasia were included in the study (n = 145).

RESULTS

Pathological subtypes 2A and 2B were predominantly frontal in location, and had a more severe epilepsy syndrome with lower intelligence quotient scores than subtypes 1A and 1B. Patients with subtype 1A FCD had less severe, later onset epilepsy that was predominantly located in the temporal lobe. Risk factors for epilepsy included febrile seizures for type 1A, head trauma for types 1A and 1B, and perinatal adverse events for type 2B. Type 2B demonstrated significantly more FLAIR signal abnormalities than the other groups. Sixty-three percent of patients overall had an Engel I outcome at 6 months follow-up. The best outcomes were in the 2B subtype, and in those who did not require an invasive EEG evaluation.

CONCLUSIONS

Clinically important differences exist between the pathological subtypes of CD, which may assist in their management, and provide further insight into their underlying pathophysiology.

Risk factors for carbamazepine elevation and toxicity following epilepsy surgery

A proportion of patients undergoing epilepsy surgery, and receiving carbamazepine (CBZ), experience significant elevations in CBZ plasma concentrations, some with associated CBZ toxicity. The objective of this study was to identify significant risk factors for elevations (>12 microg/ml) in CBZ concentrations and CBZ-induced toxicity following epilepsy surgery.

METHODS

We retrospectively examined charts of 74 inpatients (31 children and 43 adults) chronically receiving CBZ and undergoing epilepsy surgery between January 1996 and June 2000. Patient demographics, medications, type of surgery, seizure history, adverse events, CBZ doses and concentrations were evaluated.

RESULTS

51.2% of adults and 51.6% of pediatric patients had drug elevations. In the pediatric group, 12.9% had symptoms of toxicity compared to 9.3% in the adult group. Five risk factors-pre-operative CBZ dose, fentanyl dose, surgery day CBZ concentration, body weight, and blood loss-were related to post-operative CBZ concentrations. Three risk factors: age <18 years, pre-operative CBZ dose, and the surgery day CBZ (immediate pre-operative) concentration, were significantly related to the outcome measure of abnormal CBZ concentration (>12 microg/ml). Two variables significantly related to toxicity were average post-operative CBZ dose and the surgery day CBZ concentration. Increases in concentrations occurred at a mean 33+/-13.7 h (range: 11-74 h) after surgery.

DISCUSSION

Based upon our results in patients with one or more risk factors, we suggest that reduction of post-operative CBZ doses be considered.