Hand Dystonia after Focused Ultrasound Thalamotomy in Essential Tremor.

INTRODUCTION: Magnetic resonance guided focused ultrasound (MRgFUS) thalamotomy is an effective treatment for drug-resistant tremor. The most frequent side effects are ataxia, gait disturbance, paresthesias, dysgeusia, and hemiparesis. Here, we report the first case of thalamic hand dystonia rapidly occurring after MRgFUS thalamotomy of the ventral intermediate nucleus (V.im). CASE PRESENTATION: MRgFUS thalamotomy was performed in a 60-year-old left-handed patient for his disabling medically refractory essential tremor. The intervention resulted in a marked reduction of his action tremor. However, the patient developed an unvoluntary abnormal posture in his left hand a few days after the procedure with difficulty holding a cigarette between his fingers. Brain MRI revealed the expected MRgFUS lesion within the right V.im as well as an extension of the lesion anteriorly to the V.im in the ventro-oralis nucleus. Tractography showed that the lesion disrupted the dentato-rubro-thalamic tract as expected with a lesion suppressing tremor. However, the lesion also was interrupted fibers connecting to the superior frontal and pre-central cortices (primary motor cortex, premotor cortex, and supplementary area). We hypothesized that the interventional MRgFUS thalamotomy was slightly off target, which induced a dysfunction within the cortico-striato-thalamo-cortical network and the cerebello-thalamo-cortical pathway reaching a sufficient threshold of basal ganglia/cerebellum circuitry interference to induce dystonia. CONCLUSION: This rare side effect emphasizes the risk of imbalance within the dystonia network (i.e., basal ganglia-cerebello-thalamo-cortical circuit) secondary to V.im thalamotomy.

Effectiveness and reliability of hypnosis in stereotaxy: a randomized study.

BACKGROUND: Patients suffering from Parkinson's disease (PD) may experience pain during stereotactic frame (SF) fixation in deep brain stimulation (DBS). We assessed the role of hypnosis during the SF fixation in PD patients undergoing awake bilateral subthalamic nucleus (STN) DBS. METHODS: N = 19 patients were included (N = 13 males, mean age 63 years; N = 10 allocated to the hypnosis and N = 9 allocated to the control groups). Patients were randomly assigned to the interventional (hypnosis and local anesthesia) or non-interventional (local anesthesia only) groups. The primary outcome was the pain perceived (the visual analogue scale (VAS)). Secondary outcomes were stress, anxiety, and depression, as measured by the perceived stress scale (PSS) and hospital anxiety and depression scale (HADS). Procedural distress was measured using the peritraumatic distress inventory (PDI-13). RESULTS: In the hypnosis group, VASmean was 5.6 ± 2.1, versus 6.4 ± 1.2 in the control group (p = 0.31). Intervention and control groups reported similar VASmax scores (7.6 ± 2.1 versus 8.6 ± 1.6 (p = 0.28), respectively). Both groups had similar HADS scores (6.2 ± 4.3 versus 6.7 ± 1.92, p = 0.72 (HADSa) and 6.7 ± 4.2 versus 7.7 ± 3, p = 0.58 (HADSd)), so were the PSS scores (26.1 ± 6.3 versus 25.1 ± 7, p = 0.75). Evolutions of VASmean (R2 = 0.93, 95% CI [0.2245, 1.825], p = 0.03) and PDI-13 scores (R2 = 0.94, 95% CI [1.006, 6.279], p = 0.02) significantly differ over follow-up with patients in the hypnosis groups showing lower scores. CONCLUSION: In this unblinded, randomized study, hypnosis does not influence pain, anxiety, and distress during awake SF fixation but modulates pain memory over time and may prevent the integration of awake painful procedures as a bad experience into the autobiographical memory of patients suffering from PD. A randomized controlled study with more data is necessary to confirm our findings.

Semiautomatic interictal electric source localization based on long-term electroencephalographic monitoring: A prospective study.

OBJECTIVE: Electric source imaging (ESI) of interictal epileptiform discharges (IEDs) has shown significant yield in numerous studies; however, its implementation at most centers is labor- and cost-intensive. Semiautomatic ESI analysis (SAEA) has been proposed as an alternative and has previously shown benefit. Computer-assisted automatic spike cluster retrieval, averaging, and source localization are carried out for each cluster and are then reviewed by an expert neurophysiologist, to determine their relevance for the individual case. Here, we examine its yield in a prospective single center study. METHOD: Between 2017 and 2022, 122 patients underwent SAEA. Inclusion criteria for the current study were unifocal epilepsy disorder, epilepsy surgery with curative purpose, and postoperative follow-up of 2 years or more. All patients (N=40) had continuous video-electroencephalographic (EEG) monitoring with 37 scalp electrodes, which underwent SAEA. Forty patients matched our inclusion criteria. RESULTS: Twenty patients required intracranial monitoring; 13 were magnetic resonance imaging (MRI)-negative. Mean duration of analyzed EEG was 4.3 days (±3.1 days), containing a mean of 12 749 detected IEDs (±22 324). The sensitivity, specificity, and accuracy of SAEA for localizing the epileptogenic focus of the entire group were 74.3%, 80%, and 75%, respectively, leading to an odds ratio (OR) of 11.5 to become seizure-free if the source was included in the resection volume (p < .05). In patients with extratemporal lobe epilepsy, our results indicated an accuracy of 68% (OR=11.7). For MRI-negative patients (n = 13) and patients requiring intracranial EEG (n = 20), we found a similarly high accuracy of 84.6% (OR=19) and 75% (OR = 15.9), respectively. SIGNIFICANCE: In this prospective study of SAEA of long-term video-EEG, spanning several days, we found excellent localizing information and a high yield, even in difficult patient groups. This compares favorably to high-density ESI, most likely due to marked improved signal-to-noise ratio of the averaged IEDs. We propose including ESI, or SAEA, in the workup of all patients who are referred for epilepsy surgery.

Successful MRI-Guided Focused Ultrasound Thalamotomy after Ipsilateral Gamma Knife Radiosurgery for Essential Tremor: A Case Report with Video.

We report the case of a 67-year-old left-handed female patient with disabling medically refractory essential tremor who underwent successful right-sided magnetic resonance-guided focused ultrasound (MRgFUS) of the ventral intermediate nucleus after ipsilateral gamma knife radiosurgery (GKRS) thalamotomy performed 3 years earlier. The GKRS had a partial effect on her postural tremor without side effects, but there was no reduction of her kinetic tremor or improvement in her quality of life (QoL). The patient subsequently underwent a MRgFUS thalamotomy, which induced an immediate and marked reduction in both the postural and kinetic tremor components, with minor complications (left upper lip hypesthesia, dysmetria in her left hand, and slight gait ataxia). The MRgFUS-induced lesion was centered more medially than the GKRS-induced lesion and extended more posteriorly and inferiorly. The MRgFUS-induced lesion interrupted remaining fibers of the dentatorubrothalamic tract (DRTT). The functional improvement 1-year post-MRgFUS was significant due to a marked reduction of the patient's kinetic tremor. The QoL score (Quality of Life in Essential Tremor) improved by 88% and her Clinical Rating Scale for Tremor left hand score by 62%. The side effects persisted but were minor, with no impact on her QoL. The explanation for the superior efficacy of MRgFUS compared to GKRS in our patient could be due to either a poor response to the GKRS or to a better localization of the MRgFUS lesion with a more extensive interruption of DRTT fibers. In conclusion, MRgFUS can be a valuable therapeutic option after unsatisfactory GKRS, especially because MRgFUS has immediate clinical effectiveness, allowing intra-procedural test lesions and possible readjustment of the target if necessary.

Evaluation of the precision of navigation-assisted endoscopy according to the navigation tool setup and the type of endoscopes.

OBJECT: Preoperative image-based neuronavigation-assisted endoscopy during intracranial procedures is gaining great interest. This study aimed to analyze the precision of navigation-assisted endoscopy according to the navigation setup, the type of optic and its working angulation. METHODS: A custom-made box with four screws was referenced. The navigation-assisted endoscope was aligned on the screws (targets). The precision on the navigation screen was defined as the virtual distance-to-target between the tip of the endoscope and the center of the screws. Three modifiers were assessed: (1) the distance D between the box and the reference array (CLOSE 13 cm - MIDDLE 30 cm - FAR 53 cm), (2) the distance between the tip of the endoscope and the navigation array on the endoscope (close 5 cm - middle 10 cm - far 20 cm), (3) the working angulation of the endoscope (0°-endoscope and 30°-endoscope angled at 90° and 45° with the box). RESULTS: The median precision was 1.3 mm (Q1: 1.1; Q3: 1.7) with the best setting CLOSE/close. The best setting in surgical condition (CLOSE/far) showed a distance-to-target of 2.3 mm (Q1: 1.9; Q3: 2.5). The distance D was correlated to the precision (Spearman rho = 0.82), but not the distance d (Spearman rho = 0.04). The type of optic and its angulation with the box were also correlated to the precision (Spearman rho = - 0.37). The best setting was the use of a 30°-endoscope angled at 45° (1.4 mm (Q1: 1.0; Q3: 1.9)). CONCLUSION: Navigated-assisted endoscopy is feasible and offers a good precision. The navigation setup should be optimized, reducing the risk of inadvertent perifocal damage.

Slow oscillations open susceptible time windows for epileptic discharges.

OBJECTIVE: In patients with epilepsy, interictal epileptic discharges are a diagnostic hallmark of epilepsy and represent abnormal, so-called "irritative" activity that disrupts normal cognitive functions. Despite their clinical relevance, their mechanisms of generation remain poorly understood. It is assumed that brain activity switches abruptly, unpredictably, and supposedly randomly to these epileptic transients. We aim to study the period preceding these epileptic discharges, to extract potential proepileptogenic mechanisms supporting their expression. METHODS: We used multisite intracortical recordings from patients who underwent intracranial monitoring for refractory epilepsy, the majority of whom had a mesial temporal lobe seizure onset zone. Our objective was to evaluate the existence of proepileptogenic windows before interictal epileptic discharges. We tested whether the amplitude and phase synchronization of slow oscillations (.5-4 Hz and 4-7 Hz) increase before epileptic discharges and whether the latter are phase-locked to slow oscillations. Then, we tested whether the phase-locking of neuronal activity (assessed by high-gamma activity, 60-160 Hz) to slow oscillations increases before epileptic discharges to provide a potential mechanism linking slow oscillations to interictal activities. RESULTS: Changes in widespread slow oscillations anticipate upcoming epileptic discharges. The network extends beyond the irritative zone, but the increase in amplitude and phase synchronization is rather specific to the irritative zone. In contrast, epileptic discharges are phase-locked to widespread slow oscillations and the degree of phase-locking tends to be higher outside the irritative zone. Then, within the irritative zone only, we observe an increased coupling between slow oscillations and neuronal discharges before epileptic discharges. SIGNIFICANCE: Our results show that epileptic discharges occur during vulnerable time windows set up by a specific phase of slow oscillations. The specificity of these permissive windows is further reinforced by the increased coupling of neuronal activity to slow oscillations. These findings contribute to our understanding of epilepsy as a distributed oscillopathy and open avenues for future neuromodulation strategies aiming at disrupting proepileptic mechanisms.

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. Particularly, the questions of laterality and affective component in coding of odors in the OF cortex remain controversial. AIMS: This study explored whether cortical electrical stimulation of the OF and mesiotemporal brain can trigger olfactory hallucinations with special focus on olfactory percepts in terms of laterality and hedonics. MATERIALS AND METHODS: Eight patients with temporal lobe epilepsy participated in the study, at the time of invasive exploration of their epilepsy. The most distal contact of the OF and anterior hippocampus depth electrodes were stimulated (50 Hz, 0.2 ms biphasic pulse; maximal stimulation 4 mA). Patients were instructed to report any kind of sensation they might experience. Intracranial depth electrodes were localized (iElectrodes): subject-specific brain mask, subcortical segmentation and cortical parcellation based on the Destrieux atlas (FreeSurfer) were superposed to the coregistered T1-weighted MRI and CT images (SPM). The center of mass of each electrode-artifact cluster determined the electrode localization. The electrode labeling was done in patient space. To obtain the electrode coordinates in Montreal Neurological Institute (MNI) space, the images obtained previously in the patient space were first segmented and normalized (SPM). Then, the localization procedure (iElectrodes) was run again with these new normalized images in MNI space. RESULTS: No hallucination was evoked by stimulation, neither of the right nor the left hippocampus (8/8 patients). Pleasant olfactory hallucinations were evoked by OF stimulation in 5/8 patients in either hemisphere. Patients named the percept as the smell of lemon or coffee for example. Among those 5 patients, electrodes were localized in the cortex of the olfactory sulcus, medial orbital sulcus or medial OF gyrus. Increasing stimulation amplitude changed the olfactory percept identification in 3 out of those 5 patients. No affective judgement or change in perceived odor intensity was reported by the patients. No hallucination was evoked by the stimulation of the white matter of the medial OF brain in 3/8 patients independently of the hemisphere stimulated. CONCLUSIONS: This study demonstrated that stimulation of the cortex of the medial OF brain and not of its white matter elicits specific pleasant olfactory hallucinations independently of the hemisphere stimulated, supporting one symmetrical olfactory processing in human.

Increased oxytocin release precedes hyponatremia after pituitary surgery.

PURPOSE: The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is a well-known complication of transsphenoidal pituitary surgery, related to inappropriate secretion of arginine vasopressin (AVP). Its diagnosis is based on hyponatremia, with a peak of occurrence around day 7 after surgery and, to date, no early marker has been reported. In particular, copeptin levels are not predictive of hyponatremia in this case. Oxytocin (OXT) is secreted into the peripheral blood by axon terminals adjacent to those of AVP neurons in the posterior pituitary. Besides its role in childbirth and lactation, recent evidences suggested a role for OXT in sodium balance. The contribution of this hormone in the dysnatremias observed after pituitary surgery has however never been investigated. METHODS: We analyzed the urinary output of OXT in patients subjected to transsphenoidal pituitary surgery. RESULTS: While OXT excretion remained stable in patients who presented a normonatremic postoperative course, patients who were later diagnosed with SIADH-related hyponatremia presented with a significantly increased urinary secretion of OXT 4 days after surgery. CONCLUSION: Taken together, these results show for the first time that urinary OXT output remains normally stable after transsphenoidal pituitary surgery. OXT excretion however becomes abnormally high on or around 4 days after surgery in patients later developing hyponatremia, suggesting that this abnormal dynamics of OXT secretion might serve as an early marker for transsphenoidal surgery-related hyponatremia attributed to SIADH.

Single Center Experience in Cerebrospinal Fluid Dynamics Testing.

Normal pressure hydrocephalus is more complex than a simple disturbance of the cerebrospinal fluid (CSF) circulation. Nevertheless, an assessment of CSF dynamics is key to making decisions about shunt insertion, shunt malfunction, and for further management if a patient fails to improve. We summarize our 25 years of single center experience in CSF dynamics assessment using pressure measurement and analysis. 4473 computerized infusion tests have been performed. We have shown that CSF infusion studies are safe, with incidence of infection at less than 1%. Raised resistance to CSF outflow positively correlates (p < 0.014) with improvement after shunting and is associated with disturbance of cerebral blood flow and its autoregulation (p < 0.02). CSF infusion studies are valuable in assessing possible shunt malfunction in vivo and for avoiding unnecessary revisions. Infusion tests are safe and provide useful information for clinical decision-making for the management of patients suffering from hydrocephalus.

Dyskinesia-inducing lead contacts optimize outcome of subthalamic stimulation in Parkinson's disease.

BACKGROUND: Acute dyskinesias elicited by STN-DBS, here referred to as stimulation-induced dyskinesias, predict optimal clinical outcome in PD. However, it remains elusive whether stimulation-induced dyskinesias can guide DBS programming. OBJECTIVES: Here, we characterized stimulation-induced dyskinesias clinically and anatomically. We then tested whether dyskinesia-inducing contacts could be effectively programmed using independent current source technology. METHODS: We characterized stimulation-induced dyskinesias with directional and ring stimulation retrospectively in 20 patients. We then localized dyskinesia-inducing contacts by imaging coregistration and eventually programmed those contacts. RESULTS: We elicited dyskinesias in half of our patients. Dyskinesia-inducing contacts were mainly directional and were all located ventrally within the dorsolateral motor STN. When these dyskinesia-inducing contacts were programmed using independent current source technology, dyskinesia disappeared and robust antibradykinetic effects were obtained. CONCLUSION: We confirm that stimulation-induced dyskinesias are helpful clinical observations, which may guide programming of directional STN-DBS in PD. © 2019 International Parkinson and Movement Disorder Society.

Postoperative memory prognosis in temporal lobe epilepsy surgery: The contribution of postictal memory.

OBJECTIVE: The prediction of verbal memory decline after temporal lobe epilepsy (TLE) surgery remains difficult at an individual level. We evaluated the prognostic value of postictal memory testing in predicting the postoperative verbal memory function. METHODS: Sixty-three consecutive patients were included in the analysis who underwent TLE surgery at our center with preoperative interictal/postictal and postoperative memory testing. Verbal memory was evaluated using the Rey Auditory Verbal Learning Test (RAVLT). We used reliable change indices with 90% confidence interval (90% RCIs) to evaluate a significant postoperative memory decline. The sensitivity (Sn), specificity (Sp), positive predictive value (PPV), negative predictive value (NPV), area under the curve (AUC), and accuracy (ACC) were calculated. The analysis was performed for all TLE patients and for the subgroup with hippocampal sclerosis (HS). RESULTS: Left-TLE patients (n = 31) had lower verbal memory scores on RAVLT than right-TLE at 3 months (57% vs 78%) and 12 months (53% vs 78%) after surgery. The 90% RCI was estimated to be a loss of 4 out of 15 items. The predictive value was Sn = 42%, Sp = 84%, PPV = 39%, NPV = 86%, AUC = 0.630, and ACC = 76% to predict a verbal memory decline in the whole group (n = 63). In HS patients (n = 41), the postictal verbal memory test had Sn = 50%, Sp = 88%, PPV = 50%, NPV = 88%, AUC = 0.689, and ACC = 81% to predict a significant postoperative decline. SIGNIFICANCE: Postictal memory is a noninvasive bedside memory test that can help predict the postoperative verbal memory decline in patients with HS with an overall accuracy of 81%.

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. The principal outcome was the therapeutic window (difference between the amplitude thresholds for visible muscle contraction and for best rigidity control). The secondary outcome was the charge per pulse (which reflects the efficiency of the stimulation) needed to control rigidity. Two-way analysis of variance and pairwise t tests were applied. RESULTS: The therapeutic window widened when the pulse width shortened (r = -0.45; P < 0.001), and charge per pulse was reduced (P < 0.05). CONCLUSIONS: This randomized, double-blind study showed that shorter pulse widths widen the therapeutic window of STN-DBS in PD without increasing the electrical charge required to obtain the same acute clinical benefit. © 2017 International Parkinson and Movement Disorder Society.

[Obsessive compulsive disorder and deep brain stimulation, a future so close]. / Trouble obsessionnel compulsif et stimulation cérébrale profonde, un futur si proche.

The obsessive compulsive disorder (OCD) is a psychiatric disorder with a high prevalence (2­3 %), frequently causing a disabling condition. Drug and psychotherapeutic treatment is generally effective. However about 1/3 of the patients are treatment-resistant, suffering from chronic psychological distress with important sociofunctional repercussions. The identification of dysfunctional neural networks in this disease opens the door to the use of neuromodulation techniques, as deep brain stimulation (DBS). We discuss the clinical results of subthalamic nucleus DBS and the involvement of this nucleus in the pathophysiology of OCD. We emphasize the importance to confirm these results with a larger number of patients and to determine the benefits regarding the quality of life of implanted patients.

Le trouble obsessionnel compulsif (TOC) est une maladie psychiatrique fréquente (prévalence : 2­3 %) et invalidante. Le traitement pharmacologique et psychothérapeutique est globalement efficace. Un tiers des patients s'avèrent toutefois résistants, avec persistance de souffrance psychique et retentissement fonctionnel importants. L'identification précise de réseaux neuronaux dysfonctionnels dans cette maladie ouvre les portes à l'utilisation de techniques de neuromodulation, comme la stimulation cérébrale profonde (SCP). Nous discutons les résultats de la SCP du noyau sous-thalamique et l'implication de ce noyau dans la physiopathologie du TOC. Il est nécessaire de confirmer les premiers résultats de cette thérapeutique avec un nombre plus élevé de patients et de déterminer le bénéfice attendu en termes de qualité de vie.

[Advanced Parkinson's disease : indication for complex treatments]. / Maladie de Parkinson au stade avancé : indication aux traitements complexes.

Advanced Parkinson's disease (PD) is characterized by severe motor and non-motor complications that negatively impact on patients' autonomy and health-related quality of life. In early disease, the therapeutic strategy consists of gradual increase in dopaminergic treatment and levodopa dose fragmentation. In more advanced stages, this approach becomes insufficient and three therapeutic options can be considered: deep brain stimulation (DBS), continuous subcutaneous apomorphine infusion, and continuous levodopa/carbidopa intestinal gel infusion.

La maladie de Parkinson (MP) avancée est caractérisée par la présence de complications motrices et non motrices qui ont un impact significatif sur l'autonomie et la qualité de vie des patients. La stratégie thérapeutique consiste à fractionner le traitement dopaminergique, à recourir aux formes à libération prolongée, et aux inhibiteurs des enzymes de dégradation de la dopamine. Lorsque ces mesures sont insuffisantes, trois options thérapeutiques plus invasives peuvent être envisagées : la stimulation cérébrale profonde, la perfusion sous-cutanée continue d'apomorphine et l'administration intrajéjunale de gel de lévodopa/carbidopa. L'objectif de cet article est de décrire les indications, bénéfices et effets secondaires potentiels de ces traitements dits « complexes ¼.

Subthalamic stimulation may inhibit the beneficial effects of levodopa on akinesia and gait.

BACKGROUND: Gait and akinesia deterioration in PD patients during the immediate postoperative period of DBS has been directly related to stimulation in the subthalamic region. The underlying mechanisms remain poorly understood. The aim of the present study was to clinically and anatomically describe this side effect. METHODS: PD patients presenting with a worsening of gait and/or akinesia following STN-DBS, that was reversible on stimulation arrest were included. The evaluation included (1) a Stand Walk Sit Test during a monopolar survey of each electrode in the on-drug condition; (2) a 5-condition test with the following conditions: off-drug/off-DBS, off-drug/on-best-compromise-DBS, on-drug/off-DBS, on-drug/on-best-compromise-DBS, and on-drug/on-worsening-DBS, which utilized the contact inducing the most prominent gait deterioration. The following scales were performed: UPDRSIII subscores, Stand Walk Sit Test, and dyskinesia and freezing of gait scales. Localization of contacts was performed using a coregistration method. RESULTS: Twelve of 17 patients underwent the complete evaluation. Stimulation of the most proximal contacts significantly slowed down the Stand Walk Sit Test. The on-drug/on-worsening-DBS condition compared with the on-drug/off-DBS condition worsened akinesia (P = 0.02), Stand Walk Sit Test (P = 0.001), freezing of gait (P = 0.02), and improved dyskinesias (P = 0.003). Compared with the off-drug/off-DBS condition, the on-drug/on-worsening-DBS condition improved rigidity (P = 0.007) and tremor (P = 0.007). Worsening contact sites were predominantly dorsal and anterior to the STN in the anterior zona incerta and Forel fields H2. CONCLUSIONS: A paradoxical deterioration of gait and akinesia is a rare side effect following STN-DBS. We propose that this may be related to misplaced contacts, and we discuss the pathophysiology and strategies to identify and manage this complication. © 2016 International Parkinson and Movement Disorder Society.

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 (38.2%, 13/34 depth; 61.8%, 21/34 scalp electrodes only). Monitorings were invalidated when burst suppression occurred or if initial IEDRs were <5. RESULTS: Monitoring was successful for 69.2% (9/13) of the patients with depth recordings and for 4.8% (1/21) of the patients with scalp recordings. Burst suppressions precluded it in 30.8% (4/13) of the depth and in 57.1% (12/21) of the scalp recordings. Initial IEDRs were <5 for 38.1% (8/21) of the scalp recordings. Significant IEDR decreases were observed in 8/10 patients with successful monitoring. These decreases started with resection of the superior temporal gyrus. IEDRs decreased further with amygdalohippocampectomy in 3/5 patients. At the 12-month follow-up, all patients with IEDR decreases remained seizure free; both patients without did not. CONCLUSION: IEDR monitoring was possible with depth, but not with scalp electrodes. IEDR decreases started with resection of the superior temporal gyrus. A larger patient cohort is necessary to confirm the high predictive values of IEDR monitoring that could become a tool for surgery customization.

[Operative and perioperative aspects of deep brain stimulation]. / Aspects opératoires et péri-opératoires de la stimulation cérébrale profonde.

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. In a second step, the impulsion generator(s) are implanted under general anaesthesia. DBS for movement disorders has a very good efficacy and a low albeit non-zero risk of serious complications. Complications related to the material are the most common.

Electric source imaging of interictal activity accurately localises the seizure onset zone.

OBJECTIVE: It remains controversial whether interictal spikes are a surrogate of the seizure onset zone (SOZ). Electric source imaging (ESI) is an increasingly validated non-invasive approach for localising the epileptogenic focus in patients with drug-resistant epilepsy undergoing evaluation for surgery, using high-density scalp EEG and advanced source localisation algorithms that include the patient's own MRI. Here we investigate whether localisation of interictal spikes by ESI provides valuable information on the SOZ. METHODS: In 38 patients with focal epilepsy who later underwent intracranial EEG monitoring, we performed ESI of interictal spikes recorded with 128-256-channel EEG. We measured the distance between the ESI maximum and the nearest intracranial electrodes in the SOZ and irritative zone (IZ, the source of interictal spikes). The resection of the region harbouring the ESI maximum was correlated to surgical outcome. RESULTS: The median distance from the ESI maximum to the nearest electrode involved in the SOZ was 17 mm (IQR 8-27). The IZ and SOZ colocalised in most patients (median distance 0 mm, IQR 0-14), supporting the notion that localising interictal spikes is a valid surrogate for the SOZ. There was no difference in accuracy among patients with temporal or extratemporal epilepsy. In the 32 patients who underwent resective surgery, including the ESI maximum in the resection correlated with favourable outcome (p=0.03). CONCLUSIONS: Localisation of interictal spikes provides an excellent estimate of the SOZ in the majority of patients. ESI should be taken into account for the management of patients undergoing intracranial recordings.

Yield of non-invasive imaging in MRI-negative focal epilepsy.

OBJECTIVE: The absence of MRI-lesion reduces considerably the probability of having an excellent outcome (International League Against Epilepsies [ILAE] class I-II) after epilepsy surgery. Surgical success in magnetic-resonance imaging (MRI)-negative cases relies therefore mainly on non-invasive techniques such as positron-emission tomography (PET), subtraction ictal/inter-ictal single-photon-emission-computed-tomography co-registered to MRI (SISCOM), electric source imaging (ESI) and morphometric MRI analysis (MAP). We were interested in identifying the optimal imaging technique or combination to achieve post-operative class I-II in patients with MRI-negative focal epilepsy. METHODS: We identified 168 epileptic patients without MRI lesion. Thirty-three (19.6%) were diagnosed with unifocal epilepsy, underwent surgical resection and follow-up ⩾ 2 years. Sensitivity, specificity, predictive values, and diagnostic odds ratio (OR) were calculated for each technique individually and in combination (after co-registration). RESULTS: 23/33 (70%) were free of disabling seizures (75.0% with temporal and 61.5% extratemporal lobe epilepsy). None of the individual modalities presented an OR > 1.5, except ESI if only patients with interictal epileptiform discharges (IEDs) were considered (OR 3.2). On a dual combination, SISCOM with ESI presented the highest outcome (OR = 6). MAP contributed to detecting indistinguishable focal cortical dysplasia in particular in extratemporal epilepsies with a sensitivity of 75%. Concordance of PET, ESI on interictal epileptic discharges, and SISCOM was associated with the highest chance for post-operative seizure control (OR = 11). CONCLUSION: If MRI is negative, the chances to benefit from epilepsy surgery are almost as high as in lesional epilepsy, provided that multiple established non-invasive imaging tools are rigorously applied and co-registered together.

Dexamethasone in Patients with Glioblastoma: A Systematic Review and Meta-Analysis.

OBJECTIVE: Glioblastomas are the most common primary central nervous system (CNS) tumors. Although modern management strategies have modestly improved overall survival, the prognosis remains dismal, with treatment side effects often impinging on the clinical course. Glioblastomas cause neurological dysfunction by infiltrating CNS tissue and via perifocal oedema formation. The administration of steroids such as dexamethasone is thought to alleviate symptoms by reducing oedema. However, despite its widespread use, the evidence for the administration of dexamethasone is limited and conflicting. Therefore, we aimed to review the current evidence concerning the use and outcomes of dexamethasone in patients with glioblastoma. METHODS: We performed a systematic review and meta-analysis according to the PRISMA-P guidelines. We performed a restricted search using the keywords "Dexamethasone" and "Glioblastoma" on PubMed, Web of Science, Cochrane Library, and Academic Search Premier. We included studies reporting on overall survival (OS) and progression-free survival (PFS) in glioblastoma patients receiving higher or lower dexamethasone doses. The risk of bias was assessed using ROBINS-I. We performed a meta-analysis using a random effects model for OS and PFS. RESULTS: Twenty-two retrospective studies were included. Higher doses of dexamethasone were associated with poorer OS (hazard ratio 1.62, confidence interval 1.40-1.88) and PFS (1.49, 1.23-1.81). OS remained worse even when studies corrected for clinical status (1.52, 1.38-1.67). CONCLUSION: Despite the widespread use of dexamethasone in glioblastoma patients, its use is correlated with worse long-term outcomes. Consequently, Dexamethasone administration should be restricted to selected symptomatic patients. Future prospective studies are crucial to confirm these findings.