Viral burden is associated with age, vaccination, and viral variant in a population-representative study of SARS-CoV-2 that accounts for time-since-infection-related sampling bias.

In this study, we evaluated the impact of viral variant, in addition to other variables, on within-host viral burden, by analysing cycle threshold (Ct) values derived from nose and throat swabs, collected as part of the UK COVID-19 Infection Survey. Because viral burden distributions determined from community survey data can be biased due to the impact of variant epidemiology on the time-since-infection of samples, we developed a method to explicitly adjust observed Ct value distributions to account for the expected bias. By analysing the adjusted Ct values using partial least squares regression, we found that among unvaccinated individuals with no known prior exposure, viral burden was 44% lower among Alpha variant infections, compared to those with the predecessor strain, B.1.177. Vaccination reduced viral burden by 67%, and among vaccinated individuals, viral burden was 286% higher among Delta variant, compared to Alpha variant, infections. In addition, viral burden increased by 17% for every 10-year age increment of the infected individual. In summary, within-host viral burden increases with age, is reduced by vaccination, and is influenced by the interplay of vaccination status and viral variant.

Correction: Viral burden is associated with age, vaccination, and viral variant in a population-representative study of SARS-CoV-2 that accounts for time-since-infection-related sampling bias.

[This corrects the article DOI: 10.1371/journal.ppat.1011461.].

Stereotactic laser ablation for subependymal giant cell astrocytomas: personal experience and review of the literature.

PURPOSE: Subependymal giant cell astrocytomas (SEGAs) are rare tumors typically found in tuberous sclerosis patients. They typically grow in the region of the foramen of Monro and can occlude it, leading to hydrocephalus. Currently, gross total resection is the standard of care, with low rates of recurrence but high rates of complication, especially with larger lesions. Laser interstitial thermal therapy (LITT) is a newly emerging treatment modality for a variety of pathologies. Here, we present a case series of SEGAs managed via LITT and endoscopic, stereotactic septostomy. METHODS: A retrospective chart review was performed to identify three cases in which SEGAs were treated via LITT and septostomy. Stereotactic ablation was performed via magnetic resonance (MR) thermometry with laser output set to 69% for 2.5 min, with post-ablation scans for visualization of treatment area. RESULTS: Average age at surgery was 8.2 years. Pre-operative tumor volumes were 0.43, 1.51, and 3.88 cm3. Post-operative tumor volumes were 0.25, 0.21, and 0.68 cm3. Mean tumor volume reduction was 70%. No complications occurred. CONCLUSION: LITT with septostomy should be considered a viable primary or adjunct treatment modality for SEGAs.

Functional and resting-state characterizations of a periventricular heterotopic nodule associated with epileptogenic activity.

The object of this study was to extensively characterize a region of periventricular nodular heterotopia (PVNH) in an epilepsy patient to reveal its possible neurocognitive functional role(s). The authors used 3-T MRI approaches to exhaustively characterize a single, right hemisphere heterotopion in a high-functioning adult male with medically responsive epilepsy, which had manifested during late adolescence. The heterotopion proved to be spectroscopically consistent with a cortical-like composition and was interconnected with nearby ipsilateral cortical fundi, as revealed by fiber tractography (diffusion-weighted imaging) and resting-state functional connectivity MRI (rsfMRI). Moreover, the region of PVNH demonstrated two novel characterizations for a heterotopion. First, functional MRI (fMRI), as distinct from rsfMRI, showed that the heterotopion was significantly modulated while the patient watched animated video scenes of biological motion (i.e., cartoons). Second, rsfMRI, which demonstrated correlated brain activity during a task-negative state, uniquely showed directionality within an interconnected network, receiving positive path effects from patent cortical and cerebellar foci while outputting only negative path effects to specific brain foci.These findings are addressed in the context of the impact on noninvasive presurgical brain mapping strategies for adult and pediatric patient workups, as well as the impact of this study on an understanding of the functional cortical architecture underlying cognition from a neurodiversity and evolutionary perspective.

Surgical Start Time Impact on Hospital Length of Stay for Elective Inpatient Procedures.

Background Hospital length of stay (LOS) remains an important, albeit nonspecific, metric in the analysis of surgical services. Modifiable factors to reduce LOS are few in number and the ability to practically take action is limited. Surgical scheduling of elective cases remains an important task in optimizing workflow and may impact the post-surgical LOS. Methods Retrospective data from a single tertiary care academic institution were analyzed from elective adult surgical cases performed from 2017 through 2019. Emergent or urgent add-on cases were excluded. Variables included primary procedure, age, diabetes status, American Society of Anesthesiologists (ASA) class, and surgical start time. Analysis of the median LOS following surgery was performed using Mann-Whitney tests and Cox hazards model. Matched-cohort analysis of mean total hospitalization costs was performed using the Student's t-test.  Results 9,258 patients were analyzed across five surgical service lines, of which 777 patients had surgical start time after 3 PM. The median LOS for the after 3 PM group was 1 day longer than the before 3 PM start time cohort (3.0 vs 2.1, p < 0.001). Service line analysis revealed increased LOS for Orthopedics and Neurosurgery (3.0 vs 1.9, p < 0.001; 3.0 vs 2.0, p < 0.05). Multivariate analysis confirmed that start time before 3 PM predicted shorter LOS (HR = 1.214, 1.126-1.309; p < 0.001). Case-matched cost analysis for frequently performed orthopedic and neurosurgical cases with an after 3 PM start time failed to demonstrate a significant difference in total hospital charges.  Conclusion Optimization of surgical services scheduling to increase the proportion of elective surgical cases started before 3 PM has the potential to decrease post-surgical LOS for adult patients undergoing Orthopedic or Neurosurgical procedures.

Three-dimensional relationships between perisynaptic astroglia and human hippocampal synapses.

Perisynaptic astroglia are critical for normal synaptic development and function. Little is known, however, about perisynaptic astroglia in the human hippocampus. When mesial temporal lobe epilepsy (MTLE) is refractory to medication, surgical removal is required for seizure quiescence. To investigate perisynaptic astroglia in human hippocampus, we recovered slices for several hours in vitro from three surgical specimens and then quickly fixed them to achieve high-quality ultrastructure. Histological samples from each case were found to have mesial temporal sclerosis with Blumcke Type 1a (mild, moderate) or 1b (severe) pathology. Quantitative analysis through serial section transmission electron microscopy in CA1 stratum radiatum revealed more synapses in the mild (10/10 microm(3)) than the moderate (5/10 microm(3)) or severe (1/10 microm(3)) cases. Normal spines occurred in mild and moderate cases, but a few multisynaptic spines were all that remained in the severe case. Like adult rat hippocampus, perisynaptic astroglial processes were preferentially associated with larger synapses in the mild and moderate cases, but rarely penetrated the cluster of axonal boutons surrounding multisynaptic spines. Synapse perimeters were only partially surrounded by astroglial processes such that all synapses had some access to substances in the extracellular space, similar to adult rat hippocampus. Junctions between astroglial processes were observed more frequently in moderate than mild case, but were obscured by densely packed intermediate filaments in astroglial processes of the severe case. These findings suggest that perisynaptic astroglial processes associate with synapses in human hippocampus in a manner similar to model systems and are disrupted by severe MTLE pathology.

Open Resection versus Laser Interstitial Thermal Therapy for the Treatment of Pediatric Insular Epilepsy.

BACKGROUND: Various studies suggest that the insular cortex may play an underappreciated role in pediatric frontotemporal/parietal epilepsy. Here, we report on the postsurgical outcomes in 26 pediatric patients with confirmed insular involvement by depth electrode monitoring. OBJECTIVE: To describe one of the largest series of pediatric patients with medically refractory epilepsy undergoing laser interstitial thermal therapy (LITT) or surgical resection of at least some portion of the insular cortex. METHODS: Pediatric patients in whom invasive insular sampling confirmed insular involvement and who subsequently underwent a second stage surgery (LITT or open resection) were included. Complications and Engel Class outcomes at least 1 yr postsurgery were compiled as well as pathology results in the open surgical cases. RESULTS: The average age in our cohort was 10.3 yr, 58% were male, and the average length of follow-up was 2.43 ± 0.20 (SEM) yr. A total of 14 patients underwent LITT, whereas 12 patients underwent open resection. Complications in patients undergoing either LITT or open resection were mostly minimal and generally transient. Forty-three percent of patients who underwent LITT were Engel Class I, compared to 50% of patients who underwent open insular resection. CONCLUSION: Both surgical resection and LITT are valid management options in the treatment of medically refractory insular/opercular epilepsy in children. Although LITT may be a less invasive alternative to craniotomy, further studies are needed to determine its noninferiority in terms of complication rates and seizure freedom, especially in cases of cortical dysplasia that may involve extensive regions of the brain.

Neuromodulation beyond neurostimulation for epilepsy: scope for focused ultrasound.

Introduction: Epilepsy is one of the most common neurological disorders and is often difficult to control with medication. Intractable epilepsy often results in compromised quality of life (QOL), neurologic morbidity and even mortality. In carefully selected cases, resective surgery offers the best potential for cure or seizure control. However, a large proportion of patients are not suitable for resective epilepsy surgery. Neuromodulation techniques are increasingly being used to treat such refractory cases. Recently, the FDA approved Magnetic Resonance-guided Focused Ultrasound (MRgFUS) for essential tremor and this novel technology is also being explored in several other neuropsychiatric conditions and neurological disorders, including epilepsy. Area covered: While the literature is scant and scattered, the pertinent literature of the MRgFUS is reviewed with an emphasis on research relevant to its application for epilepsy. Expert opinion: Limited preliminary clinical experiences and research studies with MRgFUS ablation or neuromodulation for epilepsy have shown promising results; however, this procedure remains experimental requiring further investigations. Safe and reversible opening of the blood-brain barrier (BBB) with MRgFUS adds an additional therapeutic avenue by allowing targeted delivery of neurotherapeutics in neurological disorders, potentially including epilepsy. Ongoing clinical trials and research coupled with technological advancements contribute to strengthening the MRgFUS epilepsy field. MRgFUS could be the future technology of choice for 'ablation' or 'sononeuromodulation', and/or a 'targeted therapeutics' for epilepsy.

Invasive Insular Sampling in Pediatric Epilepsy: A Single-Institution Experience.

BACKGROUND: It has been increasingly recognized that the insular cortex plays an important role in frontotemporal-parietal epilepsy in children. The insula, however, cannot be properly interrogated with conventional subdural grids, and its anatomy makes it difficult to implicate the insula with semiology or noninvasive modalities. Frame-based, stereotactic placement of insular depth electrodes for direct extraoperative monitoring is a relatively low-risk maneuver that allows for conclusive interrogation of this region, and, in select cases, can easily be replaced with a laser applicator for minimally invasive treatment via thermoablation. OBJECTIVE: To describe the largest reported series of pediatric patients with refractory epilepsy undergoing insular depth electrode placement. METHODS: We used current procedural terminology billing records to identify cases of depth electrode insertion performed at our institution. Clinical information from patients undergoing invasive insular sampling was then retrospectively collected. RESULTS: Seventy-four insular depth electrodes were placed in 49 patients for extraoperative, inpatient monitoring. The decision to place insular depth electrodes was determined by a multidisciplinary epilepsy team. In 65.3% of cases, direct invasive sampling implicated the insula in seizure onset and prompted either thermoablation or surgical resection of some portion of the insula. There were no serious adverse effects or complications associated with the placement of insular depth electrodes. CONCLUSION: Given the low morbidity of insular depth electrode insertion and the high proportion of patients who exhibited insular involvement, it is worth considering whether insular depth electrodes should be part of the standard presurgical evaluation in children with treatment-refractory frontotemporal-parietal epilepsy.

Magnetic resonance imaging-guided laser interstitial thermal therapy as treatment for intractable insular epilepsy in children.

OBJECTIVE Seizure onset within the insula is increasingly recognized as a cause of intractable epilepsy. Surgery within the insula is difficult, with considerable risks, given the rich vascular supply and location near critical cortex. MRI-guided laser interstitial thermal therapy (LiTT) provides an attractive treatment option for insular epilepsy, allowing direct ablation of abnormal tissue while sparing nearby normal cortex. Herein, the authors describe their experience using this technique in a large cohort of children undergoing treatment of intractable localization-related epilepsy of insular onset. METHODS The combined epilepsy surgery database of Cook Children's Medical Center and Dell Children's Hospital was queried for all cases of insular onset epilepsy treated with LiTT. Patients without at least 6 months of follow-up data and cases preoperatively designated as palliative were excluded. Patient demographics, presurgical evaluation, surgical plan, and outcome were collected from patient charts and described. RESULTS Twenty patients (mean age 12.8 years, range 6.1-18.6 years) underwent a total of 24 LiTT procedures; 70% of these patients had normal findings on MRI. Patients underwent a mean follow-up of 20.4 months after their last surgery (range 7-39 months), with 10 (50%) in Engel Class I, 1 (5%) in Engel Class II, 5 (25%) in Engel Class III, and 4 (20%) in Engel Class IV at last follow-up. Patients were discharged within 24 hours of the procedure in 15 (63%) cases, in 48 hours in 6 (24%) cases, and in more than 48 hours in the remaining cases. Adverse functional effects were experienced following 7 (29%) of the procedures: mild hemiparesis after 6 procedures (all patients experienced complete resolution or had minimal residual dysfunction by 6 months), and expressive language dysfunction after 1 procedure (resolved by 3 months). CONCLUSIONS To their knowledge, the authors present the largest cohort of pediatric patients undergoing insular surgery for treatment of intractable epilepsy. The patient outcomes suggest that LiTT can successfully treat intractable seizures originating within the insula and offers an attractive alternative to open resection. This is the first description of LiTT applied to insular epilepsy and represents one of only a few series describing the use of LiTT in children. The results indicate that seizure reduction after LiTT compares favorably to that after conventional open surgical techniques.

Identification and management of intrathecal baclofen pump complications: a comparison of pediatric and adult patients.

OBJECT: Intrathecal baclofen therapy is an effective means of treating intractable spasticity and dystonia in the pediatric and adult population. The authors present a review of complications encountered in a series of 314 pump and catheter-related procedures. The identification and management of these complications will be reviewed. The authors will also identify populations that may be at increased risk for complications. METHODS: A retrospective review was performed of all procedures undertaken during the last 5 years by two surgeons at the authors' institution. Postoperative complications were reviewed. A total of 314 surgical procedures (226 pediatric and 88 adult) were performed in 195 pediatric and adult patients. This included 171 new pump and catheter implants (116 pediatric and 55 adult), 26 elective pump replacements due to end of battery life (15 pediatric and 11 adult), five elective pump repositionings per physiatrist request (three pediatric and two adult), 14 elective catheter repositionings (10 pediatric and four adult), and two normal pediatric catheter explorations. Surgical procedures for complication management included seven pump revisions (five pediatric and two adult), 48 catheter revisions (38 pediatric and 10 adult), and 41 wound revisions (37 pediatric and four adult). The majority of adult pumps were implanted subdermally, whereas in pediatric patients they were placed subfascially. In general, intrathecal catheters were placed under fluoroscopic guidance with the catheter tip placed at T-1 to T-2 for spastic quadriplegia, T-6 to T-10 for spastic diplegia, and midcervical for dystonia. No significant intraoperative complications were encountered. Overall, there was a statistically significantly higher percentage of procedures for overall complication management and wound complication management in pediatric patients compared with adult patients. CONCLUSIONS: Intrathecal baclofen therapy is a highly effective treatment option for patients with medically refractory spasticity. The catheter, pump, and wound are subject to numerous complications both at the time of implantation and throughout the life of the implanted system. Careful technique, close observation, and aggressive evaluation and correction of problems can reduce the incidence and severity of the complications when they occur.

Golf-associated head injury in the pediatric population: a common sports injury.

OBJECT: Golf-related injuries constitute a common type of sports injury in the pediatric population. The increase in the frequency of these injuries is largely attributed to the increase in the popularity of golf and greater use of golf carts by children. METHODS: The purpose of this study was to investigate the mechanisms and complications associated with golf-related injuries in the pediatric population and, by doing so, assist in the prevention of such injuries. We reviewed the charts of 2546 pediatric patients evaluated by the neurosurgery service at the authors' institution over a 6-year period. There were 64 cases of sports-related injuries. Of these, 15 (23%) were golf-related, making these injuries the second-largest group of sports-related injuries. Depressed skull fracture was the most common injury observed. Neurosurgical intervention was required in 33% of the cases. With rare exceptions, patients made good recoveries during a mean follow-up period of 22.2 months. One death occurred due to uncontrollable cerebral edema following a golf cart accident. One child required shunt placement and several revisions following an injury sustained from a golf ball. CONCLUSIONS: Children should be advised on the proper use of golf equipment as a preventive measure to avoid these injuries. Precautionary guidelines and safety training guidelines should be established. The institution of a legal minimum age required to operate a golf cart should be considered.

Advanced MR imaging of cortical dysplasia with or without neoplasm: a report of two cases.

We herein describe two cases of patients with epilepsy with occipital lobe cortical dysplasia who were studied with both MR spectroscopy and MR diffusion imaging in addition to conventional MR imaging. Greater diffusion abnormalities, as well as more marked decreases in N-acetylaspartate, were observed to occur in the patient harboring a low grade neoplasm within an area of cortical dysplasia than in the patient with cortical dysplasia alone.

Composite pleomorphic xanthoastrocytoma-ganglioglioma presenting as a suprasellar mass: case report.

OBJECTIVE AND IMPORTANCE: Composite pleomorphic xanthoastrocytoma (PXA)-ganglioglioma (GG) is a recently recognized, rare type of neoplasm that most commonly presents as a temporal seizure focus among male patients less than 30 years of age. This case represents the only reported suprasellar presentation, with the youngest reported age at diagnosis. CLINICAL PRESENTATION: We present the case of a 12-year-old boy with new-onset diplopia who was diagnosed as having a large suprasellar mass, which was presumptively designated a craniopharyngioma on the basis of its clinical and radiological appearance. INTERVENTION: Gross total resection of a well-encapsulated tumor with adjacent cysts was achieved, without postoperative neurological deficits. Frozen-section studies suggested pilocytic astrocytoma; however, the final histological diagnosis was composite PXA-GG. CONCLUSION: Composite PXA-GG, although extremely rare, may present as a pediatric suprasellar mass. The histopathological diagnosis is contingent on the demonstration of distinct coincident PXA and GG components. The prognosis after gross subtotal resection is likely favorable; however, long-term follow-up monitoring is indicated for these rare neoplasms.

A longitudinal MRI study in children with Rasmussen syndrome.

The aim of this study was to identify the presence of any neuroimaging patterns of Rasmussen syndrome using magnetic resonance imaging (MRI). This was a prospective study evaluating brain MRIs in seven children with neuropathologically proven Rasmussen syndrome. All patients were unresponsive to conventional antiepileptics; five patients subsequently underwent functional hemispherectomy, and two patients underwent cortical resection. Three to eight (mean = 4.7) MRIs per patient were performed, and neuropathologic examination of the brain was available. Serial MRIs were obtained between 12 months before and 9 months after the onset of epilepsia partialis continua. The most common region of initial MRI signal change was the frontocentral region (six patients). Three patterns of neuroimaging abnormalities were observed as follows: (1) normal MRI followed by increased signal intensity with progressive cortical atrophy over time, (2) initial increased focal signal intensity followed by decrease in spatial extent and degree of signal intensity; (3) initially increased signal intensity without further changes on follow-up scans. This observation suggests three possible distinct patterns of MRI changes in patients with Rasmussen syndrome and that the differences in these neuroimaging patterns may reflect inherent differences in the pathogenesis of Rasmussen syndrome.

Leiomyosarcomatous transformation of unknown pediatric primary brainstem lesion following radiotherapy. Case report.

Primary leiomyosarcoma of the central nervous system is rare and has been described both de novo and following temporally remote radiotherapy for a different unrelated malignancy. The authors report the case of a 42-year-old man in whom 60Co radiation treatment had been performed for an unknown primary mass in the brainstem 25 years previously. He presented with progressive neurological deterioration after undergoing many years of conservative therapy. A stereotactic biopsy sampling procedure was performed, and examination of the left cerebral pedunculopontine lesion revealed a spindle cell neoplasm. Histopathological and immunohistochemical examination of the tumor obtained from definitive resection suggested leiomyosarcomatous transformation of ganglioglioma.

Treatment of atlantoaxial instability in pediatric patients.

The atlantoaxial region has been extensively described as a spinal segment especially prone to injury in children. In this clinical review, the authors evaluate and summarize the management of 23 pediatric cases of atlantoaxial instability treated between March 1990 and October 2002. Four broad categories of atlantoaxial problems were observed-atlantoaxial rotatory subluxation in six patients, anterior-posterior atlantoaxial instability caused by ligamentous injury or congenital ligamentous laxity (10 patients), atlantoaxial fracture with or without dislocation (five patients), and atlantooccipital dislocation (two patients). Most cases (60.9%) were treated without surgical intervention, resulting in excellent outcomes; however, 21.7% of cases were treated with a cervical halo (mean patient age 72.6 months) alone for 3 months. Various techniques of surgical stabilization including transarticular screws with sublaminar wiring, transoral decompression with posterior plating, and laminectomy with Steinmann pin occipital-cervical fusion were used with good results. Both patients with atlantooccipital dislocation underwent immediate Locksley occipital-cervical fusion, with marked neurological improvement. Individualized case management must be based on clinical presentation, with internal fixation being the last resort.

Evaluation of salvage techniques for infected baclofen pumps in pediatric patients with cerebral palsy.

OBJECT: Intrathecal baclofen therapy has been used successfully for intractable spasticity in children with cerebral palsy. Infections are rare, but they are potentially life threatening if complicated by bacteremia or meningitis. Treatment without removal of the system is desirable if it can be done safely and effectively. METHODS: The Authors reviewed the records of 207 patients ranging from 3 to 18 years of age with cerebral palsy who underwent placement or revision of a baclofen pump. They identified 38 patients with suspected or documented infectious complications. Initial attempts were made to eradicate infection with the devices in situ in all patients. Methods and effectiveness of pump salvage were evaluated. RESULTS: Of the 38 patients identified, 13 (34.2%) had documented infections; 11 had deep wound/pocket empyemas and 2 had meningitis. Eight patients with deep wound infections received intravenous antibiotics alone. All required pump explantation. The remaining 3 patients underwent a washout procedure as well; the infection was cured in 1 patient. Both patients with meningitis received intravenous and intrathecal antibiotics, and both required device explantation. In addition, 25 patients (65.8%) had excessive or increasing wound erythema. No objective criteria to document a superficial infection were present. The wounds were considered suspicious and were managed with serial examinations and oral antibiotics. The erythema resolved in 24 of the 25 patients. CONCLUSIONS: In general, observation, wound care, and oral antibiotics are sufficient for wounds that are suspicious for superficial infection. For deep-seated infection, antibiotic therapy alone is generally insufficient and explantation is required. Washout procedures can be considered, but failures are common.

Dibucaine mitigates spreading depolarization in human neocortical slices and prevents acute dendritic injury in the ischemic rodent neocortex.

BACKGROUND: Spreading depolarizations that occur in patients with malignant stroke, subarachnoid/intracranial hemorrhage, and traumatic brain injury are known to facilitate neuronal damage in metabolically compromised brain tissue. The dramatic failure of brain ion homeostasis caused by propagating spreading depolarizations results in neuronal and astroglial swelling. In essence, swelling is the initial response and a sign of the acute neuronal injury that follows if energy deprivation is maintained. Choosing spreading depolarizations as a target for therapeutic intervention, we have used human brain slices and in vivo real-time two-photon laser scanning microscopy in the mouse neocortex to study potentially useful therapeutics against spreading depolarization-induced injury. METHODOLOGY/PRINCIPAL FINDINGS: We have shown that anoxic or terminal depolarization, a spreading depolarization wave ignited in the ischemic core where neurons cannot repolarize, can be evoked in human slices from pediatric brains during simulated ischemia induced by oxygen/glucose deprivation or by exposure to ouabain. Changes in light transmittance (LT) tracked terminal depolarization in time and space. Though spreading depolarizations are notoriously difficult to block, terminal depolarization onset was delayed by dibucaine, a local amide anesthetic and sodium channel blocker. Remarkably, the occurrence of ouabain-induced terminal depolarization was delayed at a concentration of 1 µM that preserves synaptic function. Moreover, in vivo two-photon imaging in the penumbra revealed that, though spreading depolarizations did still occur, spreading depolarization-induced dendritic injury was inhibited by dibucaine administered intravenously at 2.5 mg/kg in a mouse stroke model. CONCLUSIONS/SIGNIFICANCE: Dibucaine mitigated the effects of spreading depolarization at a concentration that could be well-tolerated therapeutically. Hence, dibucaine is a promising candidate to protect the brain from ischemic injury with an approach that does not rely on the complete abolishment of spreading depolarizations.

Scalp EEG does not predict hemispherectomy outcome.

BACKGROUND: Functional hemispherectomy is effective in carefully selected patients, resulting in a reduction of seizure burden up to complete resolution, improvement of intellectual development, and developmental benefit despite possible additional neurological deficit. Despite apparent hemispheric pathology on brain magnetic resonance imaging (MRI) or other imaging tests, scalp electroencephalography (EEG) could be suggestive of bilateral ictal onset or even ictal onset contralateral to the dominant imaging abnormality. We aimed to investigate the role of scalp EEG lateralization pre-operatively in predicting outcome. METHODS: We retrospectively reviewed 54 patients who underwent hemispherectomy between 1991 and 2009 at Medical College of Georgia (1991-2006) and Cincinnati Children's Hospital Medical Center (2006-2009) and had at least one year post-operative follow-up. All preoperative EEGs were reviewed, and classified as either lateralizing or nonlateralizing, for both ictal and interictal EEG recordings. RESULTS: Of 54 patients, 42 (78%) became seizure free. Twenty-four (44%) of 54 had a nonlateralizing ictal or interictal EEG. Further analysis was based on etiology of epilepsy, including malformation of cortical development (MCD), Rasmussen syndrome (RS), and stroke (CVA). EEG nonlateralization did not predict poor outcome in any of the etiology groups evaluated. CONCLUSION: Scalp EEG abnormalities in contralateral or bilateral hemispheres do not, in isolation, predict a poor outcome from hemispherectomy. Results of other non-invasive and invasive evaluations should be used to determine candidacy.