Analysis of Intraoperative Visual Evoked Potentials for Inclusion of Unstable Electroretinograms.

Purpose: The objectives of the study were to evaluate the validity of intraoperative flash visual evoked potentials (VEPs) when electroretinograms (ERGs) were unstable, to compare white versus red light-emitting diodes, and to assess the impact of luminance on ERG variability.

Methods: Thirty patients were included (Inomed system; pre- and postoperative visual fields). Possible changes in visual fields were assessed with mean defects in perimetry.

Validation of Lead-DBS β-Oscillation Localization with Directional Electrodes.

In deep brain stimulation (DBS) studies in patients with Parkinson's disease, the Lead-DBS toolbox allows the reconstruction of the location of β-oscillations in the subthalamic nucleus (STN) using Vercise Cartesia directional electrodes (Boston Scientific). The objective was to compare these probabilistic locations with those of intraoperative monopolar β-oscillations computed from local field potentials (0.5-3 kHz) recorded by using shielded single wires and an extracranial shielded reference electrode.

Electrophysiological confrontation of Lead-DBS-based electrode localizations in patients with Parkinson's disease undergoing deep brain stimulation.

Microelectrode recordings (MERs) are often used during deep brain stimulation (DBS) surgeries to confirm the position of electrodes in patients with advanced Parkinson's disease. The present study focused on 32 patients who had undergone DBS surgery for advanced Parkinson's disease. The first objective was to confront the anatomical locations of intraoperative individual MERs as determined electrophysiologically with those determined postoperatively by image reconstructions.

Introduction of a novel connection clip for the ultrasonic aspirator for subcortical continuous motor mapping.

Introduction: A connection clip to the ultrasonic aspirator handpiece was introduced for simultaneous resection and mapping of corticospinal motor tract (CST) (Kombos et al., 2001).

Research Question: To report retrospectively the use of this clip in cerebral surgery with CST mapping.

Intraoperative subcortico-cortical evoked potentials of the visual pathway under general anesthesia.

Objective: To assess whether intraoperative subcortical mapping of the visual pathways during brain surgeries was feasible.

Methods: Subcortico-cortical evoked potentials (SCEPs: 30 stimulations/site, biphasic single pulse, 1.3 Hz, 0.

The perspectives of mapping and monitoring of the sense of self in neurosurgical patients.

Surgical treatment of tumors, epileptic foci or of vascular origin, requires a detailed individual pre-surgical workup and intra-operative surveillance of brain functions to minimize the risk of post-surgical neurological deficits and decline of quality of life. Most attention is attributed to language, motor functions, and perception. However, higher cognitive functions such as social cognition, personality, and the sense of self may be affected by brain surgery.

Sensitivity and Negative Predictive Value of Motor Evoked Potentials of the Facial Nerve.

Objective:  The objective of this study was to determine the performance of the standard alarm criterion of motor evoked potentials (MEPs) of the facial nerve in surgeries performed for resections of vestibular schwannomas or of other lesions of the cerebellopontine angle.

Methods:  This retrospective study included 33 patients (16 with vestibular schwannomas and 17 with other lesions) who underwent the resection surgery with transcranial MEPs of the facial nerve. A reproducible 50% decrease in MEP amplitude, resistant to a 10% increase in stimulation intensity, was applied as the alarm criterion during surgery.

Electrical stimulation of the medial orbitofrontal cortex in humans elicits pleasant olfactory perceptions.

Background: Olfactory hallucinations can be part of epileptic seizures of orbitofrontal origin. Olfactory hallucinations, however, are rare and therefore the semiology, localization and lateralization characteristics are underdetermined. In addition, many discrepancies are found in the literature regarding olfactory processing and orbitofrontal (OF) functions and olfactory function.

Language Monitoring in Brain Surgery Under General Anesthesia.

Background: Awake surgeries for cerebral lesion resection have several limitations including patient fear, discomfort, or pain. This study aimed to determine whether components of language function could be measured under general anesthesia. In this study, the occurrence of mismatch negativity (MMN) was searched in evoked potentials for phonological sounds.

Intraoperative monitoring of olfactory function: a feasibility study.

Objective: Intraoperative neuromonitoring of the chemical senses (smell and taste) has never been performed. The objective of this study was to determine if olfactory-evoked potentials could be obtained intraoperatively under general anesthesia.

Methods: A standard olfactometer was used in the surgical theater with hydrogen sulfide (4 ppm, 200 msec).

What Is the Best Electrophysiologic Marker of the Outcome of Subthalamic Nucleus Stimulation in Parkinson Disease?

Objective: Deep brain stimulation of the subthalamic nucleus (STN) is advocated in patients with advanced Parkinson disease. Intraoperative microelectrode recordings (MER) and stimulation or imaging are applied to confirm electrode targeting. The study objective was to evaluate which intraoperative electrophysiologic marker, MER, stimulation, or local field potentials (LFP) was the most predictive of the clinical efficacy.

Low Frequency Microstimulation Is Locally Excitatory in Patients With Epilepsy.

Deep brain stimulation (DBS) could become a palliative treatment for patients with drug-resistant epilepsy for which surgery cannot be proposed. The objective of this study was to perform microstimulation to measure the effects of DBS in epilepsy locally at the level of a few neurons, with microelectrode recordings, for the first time in patients with epilepsy. Microelectrode recordings were performed before, during and after microstimulation in nine patients with refractory epilepsy.

Intraoperative monitoring with visual evoked potentials for brain surgeries.

Objective: The goal of this study was to determine the performance of intraoperative visual evoked potentials (VEPs) in detecting visual field changes.

Methods: Assessments of VEPs were performed with simultaneous retinal responses by using white light-emitting diodes protected from scialytic microscope lights. The alarm criterion was a reproducible decrease in amplitude of the VEP P100 wave of 20% or more.

Short pulse width in subthalamic stimulation in Parkinson's disease: a randomized, double-blind study.

Background: We investigated the acute effect of short pulse widths on the therapeutic window in subthalamic nucleus deep brain stimulation in Parkinson's disease.

Methods: We assessed 10 PD patients with STN-DBS at a 60-µs pulse width. We randomly and double-blindedly applied 10- to 50-µs pulse widths.

Localization of Deep Brain Stimulation Contacts Using Corticospinal/Corticobulbar Tracts Stimulation.

Background: Successful deep brain stimulation (DBS) in Parkinson's disease (PD) requires optimal electrode placement. One technique of intraoperative electrode testing is determination of stimulation thresholds inducing corticospinal/corticobulbar tracts (CSBT) motor contractions.

Objective: This study aims to analyze correlations between DBS electrode distance to CSBT and contraction thresholds, with either visual or electromyography (EMG) detection, to establish an intraoperative tool devoted to ensure safe distance of the electrode to the CSBT.

Continuous Intraoperative Monitoring of Temporal Lobe Epilepsy Surgery.

Background/aims: The monitoring of interictal epileptiform discharge rates (IEDRs) all along anterior temporal lobe resections (ATLRs) has never been reported. Here the effect of ATLR on continuous IEDR monitoring is described.

Methods: IEDRs computed automatically during entire interventions were recorded in 34 patients (38.

Prognostic Values of Motor Evoked Potentials in Insular, Precental, or Postcentral Resections.

Purpose: To determine the predictive values of motor evoked potentials (MEPs) on the muscle strength of patients undergoing insular and/or around precentral or postcentral neurosurgeries.

Methods: Neurosurgeries were performed in 104 patients with continuous MEPs elicited with direct cortical and/or transcranial stimulation (DCS, TES; alarm criterion: reproducible 50% decrease in the MEP amplitudes). Muscle strength was evaluated with the British Medical Research Council Scale, before and postoperatively (1-3 days, 3 months).

[Operative and perioperative aspects of deep brain stimulation].

Deep brain stimulation (DBS) requires the surgical implantation of a system including brain electrodes and impulsion generator(s). The nuclei targeted by the stereotaxic implantation methodology have to be visualized at best by high resolution imaging. The surgical procedure for implanting the electrodes is performed if possible under local anaesthesia to make electro-physiological measurements and to test intra-operatively the effect of the stimulation, in order to optimize the position of the definitive electrode.

Evaluation of electrode position in deep brain stimulation by image fusion (MRI and CT).

Introduction: Imaging has an essential role in the evaluation of correct positioning of electrodes implanted for deep brain stimulation (DBS). Although MRI offers superior anatomic visualization of target sites, there are safety concerns in patients with implanted material; imaging guidelines are inconsistent and vary. The fusion of postoperative CT with preoperative MRI images can be an alternative for the assessment of electrode positioning.

Effects of amygdala-hippocampal stimulation on synchronization.

Changes in EEG synchronization, i.e., spatio-temporal correlation, with amygdala-hippocampal stimulation were studied in patients with temporal lobe epilepsy.

Intraoperative angiography reloaded: a new hybrid operating theater for combined endovascular and surgical treatment of cerebral arteriovenous malformations: a pilot study on 25 patients.

Background: Multimodality treatment suites for patients with cerebral arteriovenous malformations (AVM) have recently become available. This study was designed to evaluate feasibility, safety and impact on treatment of a new intraoperative flat-panel (FP) based integrated surgical and imaging suite for combined endovascular and surgical treatment of cerebral AVM.

Methods: Twenty-five patients with AVMs to treat with combined endovascular and surgical interventions were prospectively enrolled in this consecutive case series.

Early-onset or rapidly progressive scoliosis in children: check the eyes!

Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare autosomal recessive disorder characterized by the absence of conjugate horizontal eye movements, and progressive scoliosis developing in childhood and adolescence, caused by mutations in the ROBO3 gene which has an important role in axonal guidance and neuronal migration. We describe two female children aged 12 years and 18 months, with progressive scoliosis, in whom the neurological examination showed absent conjugate horizontal eye movements, but preserved vertical gaze and convergence. Cerebral Magnetic resonance imaging findings included pontine hypoplasia, absent facial colliculi, butterfly configuration of the medulla and a deep midline pontine cleft, while Diffusion tensor imaging (DTI) maps showed the absence of decussating ponto-cerebellar fibers and superior cerebellar peduncles.

Electrode location and clinical outcome in hippocampal electrical stimulation for mesial temporal lobe epilepsy.

Purpose: To study the clinical outcome in hippocampal deep brain stimulation (DBS) for the treatment of patients with refractory mesial temporal lobe epilepsy (MTLE) according to the electrode location.

Methods: Eight MTLE patients implanted in the hippocampus and stimulated with high-frequency DBS were included in this study. Five underwent invasive recordings with depth electrodes to localize ictal onset zone prior to chronic DBS.

Tracking the source of cerebellar epilepsy: hemifacial seizures associated with cerebellar cortical dysplasia.

Traditionally, subcortical structures such as the cerebellum are supposed to exert a modulatory effect on epileptic seizures, rather than being the primary seizure generator. We report a 14-month old girl presenting, since birth, with seizures symptomatic of a right cerebellar dysplasia, manifested as paroxystic contralateral hemifacial spasm and ipsilateral facial weakness. Multimodal imaging was used to investigate both anatomical landmarks related to the cerebellar lesion and mechanisms underlying seizure generation.