Emotional facial expression and perioral motor functions of the human auditory cortex.

OBJECTIVE: We investigated the role of transverse temporal gyrus and adjacent cortex (TTG+) in facial expressions and perioral movements. METHODS: In 31 patients undergoing stereo-electroencephalography monitoring, we describe behavioral responses elicited by electrical stimulation within the TTG+. Task-induced high-gamma modulation (HGM), auditory evoked responses, and resting-state connectivity were used to investigate the cortical sites having different types of responses on electrical stimulation. RESULTS: Changes in facial expressions and perioral movements were elicited on electrical stimulation within TTG+ in 9 (29%) and 10 (32%) patients, respectively, in addition to the more common language responses (naming interruptions, auditory hallucinations, paraphasic errors). All functional sites showed auditory task induced HGM and evoked responses validating their location within the auditory cortex, however, motor sites showed lower peak amplitudes and longer peak latencies compared to language sites. Significant first-degree connections for motor sites included precentral, anterior cingulate, parahippocampal, and anterior insular gyri, whereas those for language sites included posterior superior temporal, posterior middle temporal, inferior frontal, supramarginal, and angular gyri. CONCLUSIONS: Multimodal data suggests that TTG+ may participate in auditory-motor integration. SIGNIFICANCE: TTG+ likely participates in facial expressions in response to emotional cues during an auditory discourse.

Neuropsychological outcomes after epilepsy surgery: A comparison of stereo electroencephalography and subdural electrodes.

BACKGROUND AND PURPOSE: We analyzed the association of neuropsychological outcomes after epilepsy surgery with the intracranial electrode type (stereo electroencephalography [SEEG] and subdural electrodes [SDE]), and electrical stimulation mapping (ESM) of speech/language. METHODS: Drug-resistant epilepsy patients who underwent comprehensive neuropsychological evaluation before and 1 year after epilepsy surgery were included. SEEG and SDE subgroups were matched by age, handedness, operated hemisphere, and seizure freedom. Postsurgical neuropsychological outcomes (adjusted for presurgical scores) and reliable change indices were analyzed as functions of electrode type and ESM. RESULTS: Ninety-nine patients aged 6-29 years were included with similar surgical resection/ablation volumes in the SEEG and SDE subgroups. Most of the neuropsychological outcomes were comparable between SEEG and SDE subgroups; however, Working Memory and Processing Speed were significantly improved in the SEEG subgroup. Undergoing language ESM was associated with significant improvements in Spelling, Letter-Word Identification, Vocabulary, Verbal Comprehension, Verbal Learning, and Story Memory scores, but a decline in Calculation scores. CONCLUSIONS: Intracranial evaluations with SEEG and SDE are comparable in terms of long-term postsurgical neuropsychological outcomes. Our data suggest that SEEG may be associated with improvements in working memory and processing speed, representing cognitive domains served by spatially distributed networks. Our study also supports wider use of language ESM before epilepsy surgery, preferably using other language tasks in addition to visual naming. Rather than the type of electrode, postsurgical neuropsychological outcomes are driven by whether language ESM was performed or not, with beneficial effects of language mapping.

Comparing electrical stimulation functional mapping with subdural electrodes and stereoelectroencephalography.

OBJECTIVE: Electrical stimulation mapping (ESM) is the clinical standard for functional localization with subdural electrodes (SDE). As stereoelectroencephalography (SEEG) has emerged as an alternative option, we compared functional responses, afterdischarges (ADs), and unwanted ESM-induced seizures (EISs) between the two electrode types. METHODS: Incidence and current thresholds for functional responses (sensory, motor, speech/language), ADs, and EISs were compared between SDE and SEEG using mixed models incorporating relevant covariates. RESULTS: We identified 67 SEEG ESM and 106 SDE ESM patients (7207 and 4980 stimulated contacts, respectively). We found similar incidence of language and motor responses between electrode types; however, more SEEG patients reported sensory responses. ADs and EISs occurred less commonly with SEEG than SDE. Current thresholds for language, face motor, and upper extremity (UE) motor responses and EIS significantly decreased with age. However, they were not affected by electrode type, premedication, or dominant hemispheric stimulation. AD thresholds were higher with SEEG than with SDE. For SEEG ESM, language thresholds remained below AD thresholds up to 26 years of age, whereas this relationship was inverse for SDE. Also, face and UE motor thresholds fell below AD thresholds at earlier ages for SEEG than SDE. AD and EIS thresholds were not affected by premedication. SIGNIFICANCE: SEEG and SDE have clinically relevant differences for functional brain mapping with electrical stimulation. Although evaluation of language and motor regions is comparable between SEEG and SDE, SEEG offers a higher likelihood of identifying sensory areas. A lower incidence of ADs and EISs, and a favorable relationship between functional and AD thresholds suggest superior safety and neurophysiologic validity for SEEG ESM than SDE ESM.

Clinical validation of magnetoencephalography network analysis for presurgical epilepsy evaluation.

OBJECTIVE: To clinically validate the connectivity-based magnetoencephalography (MEG) analyses to identify seizure onset zone (SOZ) with comparing to equivalent current dipole (ECD). METHODS: The ECD cluster was quantitatively analyzed by calculating the centroid of the cluster and maximum distance (the largest distance between all dipoles). The "primary hub" was determined by the highest eigencentrality. The distribution of nodes in the top 5% of eigenvector centrality values was quantified by generating the convex hull between each node. RESULTS: Thirty-one patients who underwent MEG, stereotactic-EEG, and focal surgery were included. The primary hub was significantly closer to the sEEG-defined SOZ compared to ECD (p = 0.009). The seizure freedom positive and negative predictive values of complete ECD cluster and primary hub resections did not significantly differ, although complete resection of the primary hub showed slightly better negative predictive value (ECD: 50.0% NPV, hub: 64.7% NPV). Both quantitative ECD and functional connectivity analyses suggested that spatially restricted dipole distributions and higher connectivity in a smaller region correlate with better seizure outcomes. CONCLUSIONS: Our findings suggest that MEG network analysis could be a valuable complement to the ECD methods. SIGNIFICANCE: The results of this study are an important step towards using non-invasive neurophysiologic recordings to accurately define the epileptic network.

Impact of radiotracer injection latency and seizure duration on subtraction ictal SPECT co-registered to MRI (SISCOM) performance in children.

OBJECTIVE: We evaluated the impact of radiotracer injection latency and post-injection seizure duration on subtraction ictal SPECT co-registered to MRI (SISCOM) test performance in identifying the epileptogenic zone (EZ) in children with drug-resistant epilepsy who had undergone a resective epilepsy surgery. METHODS: SISCOM concordance with the EZ was retrospectively reviewed to evaluate its performance in 113 children. The impact of radiotracer injection latency and post-injection seizure duration was evaluated for their predictive value of SISCOM localization accuracy. RESULTS: The overall sensitivity and specificity of SISCOM in identifying an EZ was 64.8% (95%CI = 50.6-77.3) and 40.7% (95%CI = 28.1-54.3). The positive likelihood ratio and diagnostic odd ratio was 1.09 (95%CI = 0.80-1.48) and 1.26 (95%CI = 0.59-2.71), respectively. Logistic regression showed that injection latency and post-injection seizure duration did not significantly predict the probability of true positive SISCOM (p-value = 0.45 and 0.29, respectively). CONCLUSION: Radiotracer injection latency and post-injection seizure duration were not shown to have a statistical significant impact on SISCOM performance in identifying the EZ. SIGNIFICANCE: This study demonstrates that further study of factors contributing to the performance of SISCOM in EZ identification in children is needed.

Language and motor function thresholds during pediatric extra-operative electrical cortical stimulation brain mapping.

OBJECTIVE: To examine current thresholds and their determinants for language and motor mapping with extra-operative electrical cortical stimulation (ECS). METHODS: ECS electrocorticograph recordings were reviewed to determine functional thresholds. Predictors of functional thresholds were found with multivariable analyses. RESULTS: In 122 patients (age 11.9±5.4years), average minimum, frontal, and temporal language thresholds were 7.4 (± 3.0), 7.8 (± 3.0), and 7.4 (± 3.1) mA respectively. Average minimum, face, upper and lower extremity motor thresholds were 5.4 (± 2.8), 6.1 (± 2.8), 4.9 (± 2.3), and 5.3 (± 3.3) mA respectively. Functional and after-discharge (AD)/seizure thresholds were significantly related. Minimum, frontal, and temporal language thresholds were higher than AD thresholds at all ages. Minimum motor threshold was higher than minimum AD threshold up to 8.0years of age, face motor threshold was higher than frontal AD threshold up to 11.8years age, and lower subsequently. UE motor thresholds remained below frontal AD thresholds throughout the age range. CONCLUSIONS: Functional thresholds are frequently above AD thresholds in younger children. SIGNIFICANCE: These findings raise concerns about safety and neurophysiologic validity of ECS mapping. Functional and AD/seizure thresholds relationships suggest individual differences in cortical excitability which cannot be explained by clinical variables.

After-discharges and seizures during pediatric extra-operative electrical cortical stimulation functional brain mapping: Incidence, thresholds, and determinants.

OBJECTIVE: This study examined the incidence, thresholds, and determinants of electrical cortical stimulation (ECS)-induced after-discharges (ADs) and seizures. METHODS: Electrocorticograph recordings were reviewed to determine incidence of ECS-induced ADs and seizures. Multivariable analyses for predictors of AD/seizure occurrence and their thresholds were performed. RESULTS: In 122 patients, the incidence of ADs and seizures was 77% (94/122) and 35% (43/122) respectively. Males (odds ratio [OR] 2.92, 95% CI 1.21-7.38, p=0.02) and MRI-negative patients (OR 3.69, 95% CI 1.24-13.7, p=0.03) were found to have higher odds of ECS-induced ADs. A significant trend for decreasing AD thresholds with age was seen (regression co-efficient -0.151, 95% CI -0.267 to -0.035, p=0.011). ECS-induced seizures were more likely in patients with lateralized functional imaging (OR 6.62, 95% CI 1.36-55.56, p=0.036, for positron emission tomography) and presence of ADs (OR 3.50, 95% CI 1.12-13.36, p=0.043). CONCLUSIONS: ECS is associated with a high incidence of ADs and seizures. With age, current thresholds decrease and the probability for AD/seizure occurrence increases. SIGNIFICANCE: ADs and seizures during ECS brain mapping are potentially hazardous and affect its functional validity. Thus, safer method(s) for brain mapping with improved neurophysiologic validity are desirable.

Clinical factors predict surgical outcomes in pediatric MRI-negative drug-resistant epilepsy.

PURPOSE: Lack of a potentially epileptogenic lesion on brain magnetic resonance imaging (MRI) is a poor prognostic marker for epilepsy surgery. We present a single-center series of childhood-onset MRI-negative drug-resistant epilepsy (DRE) and analyze surgical outcomes and predictors. METHODS: Children with MRI-negative DRE who had resective surgery from January 2007 to December 2013 were identified using an institutional database. Relevant clinical, neurophysiological, imaging, and surgical data was extracted. The primary outcome measure was seizure freedom. Predictors of seizure freedom were obtained using multivariate logistic regression. RESULTS: Out of 47 children with MRI-negative DRE, 12 (25.5%) were seizure free (International League Against Epilepsy [ILAE] outcome class I), after mean follow-up of 2.75 (±1.72) years. Seizure-free proportion was significantly higher in patients with single seizure semiology and concordant ictal EEG (50.0% vs. 15.2%, p=0.025). Multivariate analysis using only non-invasive pre-surgical data showed that children with daily seizures (OR 0.02, 95% CI<0.001-0.55), and earlier onset of seizures (OR 0.72, 95% CI 0.52-0.99) were less likely to be seizure-free. Also, each additional anti-epileptic drug (AED) tried before surgery decreased the probability of seizure-free outcome (OR 0.16, 95% CI 0.04-0.63). Repeat multivariate analysis after including surgical variables found no additional significant predictors of seizure-freedom. Cortical dysplasia (ILAE type IB) was the commonest histopathology. CONCLUSION: Surgical outcomes in children with MRI-negative DRE are determined by clinical factors including seizure frequency, age of onset of seizures, and number of failed AEDs.

Vagus Nerve Stimulation for Electrographic Status Epilepticus in Slow-Wave Sleep.

BACKGROUND: Electrographic status epilepticus in slow sleep or continuous spike and waves during slow-wave sleep is an epileptic encephalopathy characterized by seizures, neurocognitive regression, and significant activation of epileptiform discharges during nonrapid eye movement sleep. There is no consensus on the diagnostic criteria and evidence-based optimal treatment algorithm for children with electrographic status epilepticus in slow sleep. PATIENT DESCRIPTION: We describe a 12-year-old girl with drug-resistant electrographic status epilepticus in slow wave sleep that was successfully treated with vagus nerve stimulation. Her clinical presentation, presurgical evaluation, decision-making, and course after vagus nerve stimulator implantation are described in detail. FINDINGS: After vagus nerve stimulator implantation, the girl remained seizure free for more than a year, resolved the electrographic status epilepticus in slow sleep pattern on electroencephalography, and exhibited significant cognitive improvement. CONCLUSION: Vagus nerve stimulation may be considered for electrographic status epilepticus in slow sleep.

Central sleep apnea: does stabilizing sleep improve it?

Central sleep apnea is not uncommon in children with neurologic disorders. The mechanisms include increased ventilatory chemosensitivity to carbon dioxide level. Conventional treatments include oxygen, noninvasive ventilation, and in patients with heart failure, improving cardiac output. Here, we present a case of a 9-year-old male with Angelman syndrome, epilepsy, insomnia, and central sleep apnea. The patient was initially evaluated for nighttime awakenings and pauses in breathing. Sustained-release melatonin was used to improve his nighttime awakenings. A polysomnography confirmed central sleep apnea. We saw a reduction in arousals and improvement in insomnia with sustained-release melatonin. On a repeat study, central sleep apnea was improved. We hypothesize that sustained-release melatonin, by improving sleep continuity and reducing arousals, might improve central sleep apnea. Studies are needed to test the hypothesis.

Seizure recurrence risk following a first seizure in neurologically normal children.

PURPOSE: To define seizure recurrence rates in normal children who had had a single seizure and to define electroencephalography (EEG) or magnetic resonance imaging (MRI) utility in predicting seizure recurrence. METHODS: We studied 150 children (6 to 14 years) with a first afebrile, unprovoked seizure. Inclusion criteria were: Normal physical and neurological examination, undergone EEG and MRI studies of the brain, and followed for at least 27 months. These children participated in an ongoing prospective study of new onset seizures in childhood. RESULTS: The seizure recurrence rate was 66.4%. An abnormal EEG had no association with seizure recurrence at 9, 18, or 27 months (p = 0.1806, p = 0.2792, and p = 0.2379, respectively). A "significant" MRI abnormality, which occurred in 16.0% of patients, was associated with an increased seizure recurrence risk at 9 months (p = 0.0389) but not at 18 or 27 months. DISCUSSION: EEG findings poorly predict recurrence after a single seizure. The high rate of MRI abnormalities suggests that MRI may need consideration as a routine test to evaluate epilepsy in normal children.

Vagus nerve stimulation in children with mitochondrial electron transport chain deficiencies.

We retrospectively investigated outcome data for vagus nerve stimulation (VNS) in children less than 12 years of age with intractable seizures and mitochondrial disease. Five children with a mitochondrial disease, due to electron transport chain deficiency, were studied. Information was collected from clinic visits prior to, and subsequent to, VNS implantation. Data were collected by type and frequency of seizures, encephalogram and neuroimaging findings, and medication history. Four of the children had predominantly myoclonic seizures, while the other child had focal seizures with secondary generalization and myoclonic seizures. All five children did not have significant reduction in seizure frequency with VNS. VNS may not be an effective method to control myoclonic seizures in children with electron transport chain disorders.