EEG analysis in anti-NMDA receptor encephalitis: Description of typical patterns.

OBJECTIVE: To describe different electroencephalogram (EEG) patterns and epileptic features in patients with anti-N-methyl-D-aspartate receptor encephalitis (anti-NMDARE), their timeline in the course of the disease, their correlation with clinical data and outcome. METHODS: We retrospectively analyzed EEG recordings between November 2007 and June 2016 in 24 consecutive patients. RESULTS: Three EEG patterns were described: Excessive Beta Activity range 14-20 Hz (EBA) in 71% of patients, Extreme Delta Brush (EDB) in 58% and Generalized Rhythmic Delta Activity (GRDA) in 50%. They followed a chronological organization in the course of the disease: EBA appeared first, followed by EDB and then GRDA, as the median time of appearance for EBA, EDB and GRDA was respectively 10, 16.5 and 21.5 days. The presence of GRDA was strongly associated with concomitant abnormal movements (p < 0.001). CONCLUSION: This study focuses on EEG and epileptic abnormalities in anti-NMDARE. Beyond EDB that were already reported (Schmitt et al., 2012), GRDA seems to be a very frequent pattern. Its rhythmic aspect should not be misinterpreted as seizure or status epilepticus, to avoid antiepileptic treatments intensification. SIGNIFICANCE: This study comforts the importance of EEG in anti-NMDARE, with a better description of EEG abnormalities for a better treatment management.

Epilepsy surgery: A therapeutic patient education program.

Before the creation of a therapeutic patient education (TPE) program for epilepsy surgery, a needs analysis was conducted with 29 people, including patients (n=13), family members (n=9) and healthcare providers (n=7). Most of them highlighted the psychological difficulties of the surgical process, and the need for considerably more precise information concerning the immediate postoperative period. In addition, several patients and/or family members requested meeting with a patient who had undergone the surgery. The majority of subjects were interested in epilepsy-surgery TPE. These data were important in the creation of our TPE program and, more generally, for the management of these patients.

[Electrophysiological testing in spinal cord tumors]. / Les explorations neurophysiologiques dans les tumeurs médullaires.

Evoked potentials (EPs) are useful to evaluate the functional impairment of motor and somatosensory pathways in spinal cord tumors. Conduction through pyramidal tracts is evaluated by motor EPs (MEPs) elicited by transcranial stimulation, magnetic for awake patients or electric in the operating room. Somatosensory EPs (SEPs) and laser EPs (LEPs) are complementary procedures to explore conduction in dorsal columns and spinothalamic tracts, respectively. MEPs as well as SEPs show conduction abnormalities in about 60% of cases with a sensitivity that increases up to 70% when both procedures are carried out. Abnormalities are observed in the absence of any clinical sign in respectively 7% and 15% of cases for MEPs and SEPs. Multilevel stimulations for SEPs recordings permit to detect segmental dysfunction in 70% in case of cervical TIM, even in the absence of clinical signs. LEPs are useful in specific clinical situations: they allow a dermatomal stimulation and are correlated to segmental thermoalgic anaesthesia. Electrophysiological testing plays an important role in the diagnostic and therapeutic strategy: before surgery, MEPs and SEPs objectively evaluate the functional impairment directly related to the lesion. They also help by permitting a follow-up, either before surgery when the surgical decision is delayed because of a good clinical tolerance of the lesion, or after operation to evaluate the functional evolution. Intraoperative monitoring of MEPs and SEPs allows informing the surgeon about the impact on each surgical manipulation. No prospective randomized study has been performed to date to compare clinical evolution after surgery with or without monitoring. Nevertheless, a wide consensus became established in favor of monitoring to limit the risk of postoperative definite deficit and to permit an optimal surgical resection without risk when responses are preserved.

Optimal parameters of transcranial electrical stimulation for intraoperative monitoring of motor evoked potentials of the tibialis anterior muscle during pediatric scoliosis surgery.

OBJECTIVE: Transcranial electric stimulation elicited muscle motor evoked potentials (TESmMEPs) is one of the best methods for corticospinal tract's function monitoring during spine and spinal cord surgeries. A train of multipulse electric stimulation is required for eliciting TESmMEPs under general anaesthesia. Here, we investigated the best stimulation parameters for eliciting and recording tibialis anterior's TESmMEPs during paediatric scoliosis surgery. PATIENTS AND METHODS: Numbers of pulses (NOP), inter-stimulus intervals (ISI) and current intensities allowing the best size tibialis anterior muscle's TESmMEPs under general anaesthesia, were tested and collected during 77 paediatric scoliosis surgery monitoring procedures in our hospital. Individual pulse duration was kept at 0.5 ms and stimulating electrodes were positioned at C1 and C2 (International 10-20-EEG-System) during all the tests. RESULTS: The NOP used for eliciting the best tibialis anterior TESmMEPs response was 5, 6, and 7 respectively in 21 (27%), 47 (61%) and 9 (12%) out of the 77 patients. The ISI was 2, 3 and 4 ms respectively in 13 (17%), 55 (71%) and 9 (12%) of them. The current intensity used varied from 300 to 700 V (mean: 448±136 V). CONCLUSION: Most patients had 6 as best NOP (61%) and 3 ms as best ISI (71%). These findings support that a NOP of 6 and an ISI of 3 ms should be preferentially used as optimal stimulation settings for intraoperative tibialis anterior muscle's TESmMEPs eliciting and recording during paediatric scoliosis surgery.

Intraoperative neurophysiologic monitoring in spine surgery. Developments and state of the art in France in 2011.

Intraoperative spinal cord monitoring consists in a subcontinuous evaluation of spinal cord sensory-motor functions and allows the reduction the incidence of neurological complications resulting from spinal surgery. A combination of techniques is used: somatosensory evoked potentials (SSEP), motor evoked potentials (MEP), neurogenic motor evoked potentials (NMEP), D waves, and pedicular screw testing. In absence of intraoperative neurophysiological testing, the intraoperative wake-up test is a true form of monitoring even if its latency long and its precision variable. A 2011 survey of 117 French spinal surgeons showed that only 36% had neurophysiological monitoring available (public healthcare facilities, 42%; private facilities, 27%). Monitoring can be performed by a neurophysiologist in the operating room, remotely using a network, or directly by the surgeon. Intraoperative alerts allow real-time diagnosis of impending neurological injury. Use of spinal electrodes, moved along the medullary canal, can determine the lesion level (NMEP, D waves). The response to a monitoring alert should take into account the phase of the surgical intervention and does not systematically lead to interruption of the intervention. Multimodal intraoperative monitoring, in presence of a neurophysiologist, in collaboration with the anesthesiologist, is the most reliable technique available. However, no monitoring technique can predict a delayed-onset paraplegia that appears after the end of surgery. In cases of preexisting neurological deficit, monitoring contributes little. Monitoring of the L1-L4 spinal roots also shows low reliability. Therefore, monitoring has no indication in discal and degenerative surgery of the spinal surgery. However, testing pedicular screws can be useful. All in all, thoracic and thoracolumbar vertebral deviations, with normal preoperative neurological examination are currently the essential indication for spinal cord monitoring. Its absence in this indication is a lost opportunity for the patient. If neurophysiological means are not available, intraoperative wake-up test is a minimal obligation.

[Cervical spondylotic myelopathy: motor and somatosensory evoked potentials, clinical and radiological correlation]. / Myélopathie cervicarthrosique: intérêt des explorations électrophysiologiques et corrélations avec les données radiologiques.

Somatosensory and motor evoked potentials (EPs) have been recorded in 38 patients with cervical spondylosis, documented by MRI. All were symptomatic, 23 presented with myelopathy. Somatosensory evoked potentials were abnormal in 66p.cent as well as motor evoked potentials. The N13 potential, generated by the posterior dorsal horn of the cervical spinal cord, was abnormal in 63p.cent of patients and was the only disorder detected in 12p.cent. Together, somatosensory and motor evoked potentials were abnormal in 82p.cent of patients. There was no correlation between EPs findings and radiological data. Similary, MRI and clinical data were agreeing in only 50p.cent of patients. When a spondylotic myelopathy is suspected, SEPs proved more sensitive to detect somatosensory dysfunctionning than clinical testing and radiological data were discordant with clinical status in 50p.cent of cases. In order to obtain a high sensitivity, both somatosensory and motor evoked potentials should be recorded on all limbs with a special attention to segmental cervical and cervico-medullary responses. EPs data help to identify patients with cervical cord dysfunction and thus contribute to the therapeutic decision for surgery.

[Exploration of intraspinal tumors using evoked motor potentials (EMP): correlations with data of evoked somatosensory potentials]. / Exploration par les potentials évoqués moteurs (PEM) des tumeurs intrarachidiennes: correlations avec les données des potentials évoqués somethésiques (PES).

MEPs to transcutaneous magnetic stimulation have been recorded in 43 patients with an intraspinal tumor documented by MRI. The tumor was extramedullary in 18 patients and intramedullary In 25. MEPs were abnormal in 62.8% of patients. There were no significant differences in the rate of MEP abnormalities according to the lesion site or the histological findings, except for meningiomas which showed abnormal MEPs in all eight patients included in this series. The percentage of patients with abnormal MEPs was 9.3% despite the absence of any clinical symptom of central motor pathway dysfunction. Infraclinical MEPs abnormalities were observed in 24% of explored limbs. Median and tibial nerves somatosensory evoked potentials (SEPs) were recorded in 41 patients and showed abnormalities of central conduction or of segmental spinal responses in 65.9% of the cases. When combining data from MEP and SEPs, abnormalities were observed in 70.7% of patients (29/41). Five patients (12.2%) had abnormal MEPs, but normal SEPs, and four other patients (9.8%) had abnormal SEPs, but normal MEPs. This finding suggests that both MEPs and SEPs should be recorded for presurgical evaluation of-intraspinal tumor.