The contribution of EEG to assess and treat motor disorders in multiple sclerosis

OBJECTIVE

Electroencephalography (EEG) can highlight significant changes in spontaneous electrical activity of the brain produced by altered brain network connectivity linked to inflammatory demyelinating lesions and neuronal loss occurring in multiple sclerosis (MS). In this review, we describe the main EEG findings reported in the literature to characterize motor network alteration in term of local activity or functional connectivity changes in patients with MS (pwMS).

METHODS

A comprehensive literature search was conducted to include articles with quantitative analyses of resting-state EEG recordings (spectrograms or advanced methods for assessing spatial and temporal dynamics, such as coherence, theory of graphs, recurrent quantification, microstates) or dynamic EEG recordings during a motor task, with or without connectivity analyses.

RESULTS

In this systematic review, we identified 26 original articles using EEG in the evaluation of MS-related motor disorders. Various resting or dynamic EEG parameters could serve as diagnostic biomarkers of motor control impairment to differentiate pwMS from healthy subjects or be related to a specific clinical condition (fatigue) or neuroradiological aspects (lesion load).

CONCLUSIONS

We highlight some key EEG patterns in pwMS at rest and during movement, both suggesting an alteration or disruption of brain connectivity, more specifically involving sensorimotor networks.

SIGNIFICANCE

Some of these EEG biomarkers of motor disturbance could be used to design future therapeutic strategies in MS based on neuromodulation approaches, or to predict the effects of motor training and rehabilitation in pwMS.

Motor function in multiple sclerosis assessed by navigated transcranial magnetic stimulation mapping

INTRODUCTION

Impaired motor function is a major cause of disability in multiple sclerosis (MS), involving various neuroplasticity processes typically assessed by neuroimaging. This study aimed to determine whether navigated transcranial magnetic stimulation (nTMS) could also provide biomarkers of motor cortex plasticity in patients with MS (pwMS).

METHODS

nTMS motor mapping was performed for hand and leg muscles bilaterally. nTMS variables included the amplitude and latency of motor evoked potentials (MEPs), corticospinal excitability measures, and the size of cortical motor maps (CMMs). Clinical assessment included disability (Expanded Disability Status Scale, EDSS), strength (MRC scale, pinch and grip), and dexterity (9-hole Pegboard Test).

RESULTS

nTMS motor mapping was performed in 68 pwMS. PwMS with high disability (EDSS ≥ 3) had enlarged CMMs with less dense distribution of MEPs and various MEP parameter changes compared to pwMS with low disability (EDSS < 3). Patients with progressive MS had also various MEP parameter changes compared to pwMS with relapsing remitting form. MRC score correlated positively with MEP amplitude and negatively with MEP latency, pinch strength correlated negatively with CMM volume and dexterity with MEP latency.

CONCLUSIONS

This is the first study to perform 4-limb cortical motor mapping in pwMS using a dedicated nTMS procedure. By quantifying the cortical surface representation of a given muscle and the variability of MEP within this representation, nTMS can provide new biomarkers of motor function impairment in pwMS. Our study opens perspectives for the use of nTMS as an objective method for assessing pwMS disability in clinical practice.

Event-related desynchronization and synchronization in multiple sclerosis

BACKGROUND

Motor preparation and execution can be impaired in patients with multiple sclerosis (pwMS). These neural processes can be assessed using electroencephalography (EEG). During a self-paced movement, EEG signal amplitude decreases before movement (event-related desynchronization, ERD) and increases after movement (event-related synchronization, ERS).

OBJECTIVE

To reappraise ERD/ERS changes in pwMS compared to healthy controls (HC).

METHODS

This single-center study included 13 pwMS and 10 sex/age-matched HC. 60-channel EEG was recorded during two self-paced movements of the right hand: a simple index finger extension task and a more complex finger tapping task. Clinical variables included MS type, sex, age, disease duration, disability, grip strength, fatigue and attentional performance. EEG variables included ERD and ERS onset latency, duration, and amplitude determined using two methods of signal analyses (based on visual or automated determination) in the alpha and beta frequency bands in five cortical regions: right and left frontocentral and centroparietal regions and a midline region. Neuroimaging variables included the volumes of four deep brain structures (thalamus, putamen, pallidum and caudate nucleus) and the relative lesion load.

RESULTS

ERD/ERS changes in pwMS compared to HC were observed only in the beta band. In pwMS, beta-ERD had a delayed onset in the midline and right parietocentral regions and a shortened duration or increased amplitude in the parietocentral region; beta-ERS had a shorter duration, delayed onset, or reduced amplitude in the left parieto/frontocentral region. In addition, pwMS with a more delayed beta-ERD in the midline region had less impaired executive functions but increased caudate nuclei volume, while pwMS with a more delayed beta-ERS in the parietocentral region contralateral to the movement had less fatigue but increased thalami volume.

CONCLUSION

This study confirms an alteration of movement preparation and execution in pwMS, mainly characterized by a delayed cortical activation (ERD) and a delayed and reduced post-movement inhibition (ERS) in the beta band. Compensatory mechanisms could be involved in these changes, associating more preserved clinical performance and overactivation of deep brain structures.

[Alexithymia in Multiple Sclerosis - Narrative Review]

Alexithymia is a multidimensional construct of personality implicating difficulties in identifying and describing another's feelings, and externally oriented thinking. It is broadly reported in psychiatric patients but has gained little attention regarding its occurrence and pathophysiology in multiple sclerosis (MS). This narrative review aims to address prevalence, etiology, neurobiological, and clinical findings of alexithymia. The prevalence of alexithymia in MS ranges from 10 to 53%. There seems to be an association with anxiety, depression, fatigue, and some aspects of social cognition, while the relationship with clinical and classical cognitive variables was rarely evaluated. Only a few studies referred to its pathophysiology assuming an aberrant interhemispheric transfer or regional cerebral abnormalities. The prevalence of alexithymia in MS and the potential negative impact on quality of life and interpersonal communication could severely impact clinical MS management and a screnning for these factors should be mandatory. Thus, further evaluation is needed concerning its relationship with clinical, emotional, and cognitive confounders. Large-scale studies employing neuroimaging techniques are needed for a better understanding of the neural underpinnings of this MS feature.

Effects of the TENS device, Exopulse Mollii Suit, on pain related to fibromyalgia: An open-label study

Fibromyalgia is characterized by diffuse and chronic pain, that is often only partially alleviated by the available pharmacological treatments. Therefore, nonpharmacological interventions such as transcutaneous electrical stimulation (TENS) are highly needed to improve the quality of life of this population. However, the classical TENS devices offer a limited number of electrodes and are not adapted to this diffuse painful condition. For these reasons, we aimed to assess the effects of a new TENS device, the Exopulse Mollii Suit, that can stimulate up to 40 muscle groups integrated into pants and jackets and connected to a control unit. We report the data of 50 patients who received one session of active stimulation (pulse intensity 2 mA, and pulse frequency 20 Hz). Pain intensity was evaluated by means of the visual analogue scale (VAS), before (T0) and after the session (T1), and 24 h later (T24). Compared to baseline scores, a significant decrease in VAS was observed after the session (p<0.001), and 24 h later (p<0.001). T1 scores were significantly lower than T24 scores (p<0.001). Therefore, this new system seems to exert analgesic effects whose mechanisms primarily evoke the theory of "gate control". The effects were transient and started to decrease the following day, highlighting the need for additional studies to better evaluate the long-term effects of this intervention on pain, mood, and quality of life.

Spinal meningiomas, from biology to management - A literature review

Meningiomas arise from arachnoidal cap cells of the meninges, constituting the most common type of central nervous system tumors, and are considered benign tumors in most cases. Their incidence increases with age, and they mainly affect females, constituting 25-46% of primary spinal tumors. Spinal meningiomas could be detected incidentally or be unraveled by various neurological symptoms (e.g., back pain, sphincter dysfunction, sensorimotor deficits). The gold standard diagnostic modality for spinal meningiomas is Magnetic resonance imaging (MRI) which permits their classification into four categories based on their radiological appearance. According to the World Health Organization (WHO) classification, the majority of spinal meningiomas are grade 1. Nevertheless, they can be of higher grade (grades 2 and 3) with atypical or malignant histology and a more aggressive course. To date, surgery is the best treatment where the big majority of meningiomas can be cured. Advances in surgical techniques (ultrasonic dissection, microsurgery, intraoperative monitoring) increase the complete resection rate. Operated patients have a satisfactory prognosis, even in those with poor preoperative neurological status. Adjuvant therapy has a growing role in treating spinal meningiomas, mainly in the case of subtotal resection and tumor recurrence. The current paper reviews the fundamental epidemiological and clinical aspects of spinal meningiomas, their histological and genetic characteristics, and their management, including the various surgical novelties and techniques.

CT-Guided Aspiration of a Hemorrhagic Tarlov Cyst for the Treatment of a Post-Partum Sciatica: A Case Report and a Review of the Literature

Background

Tarlov or perineural cysts are dilations of nerve roots resulting from a pathologically increased cerebrospinal fluid pressure. Although it is very common in the general population, most of these cysts remain asymptomatic. In some cases, they can evolve and exert pressure on neural elements, independently from their initial size.

Case report

In this paper, we describe the case of a 33-year-old female known to have asymptomatic multiple and large radicular and pelvic Tarlov cysts. One cyst located in the right pelvic space progressed acutely after delivery, inducing a painful sciatica without neurological deficit. The intracystic bleeding can be a direct consequence of the delivery, leading to an acute and mechanical local compression of the right S1 root. A CT-guided puncture and aspiration allowed a complete recovery. This case report was completed by a review of the literature of these rare intracystic Tarlov bleedings.

Conclusions

Intracystic hemorrhage is a rare complication of Tarlov cysts. Delivery-induced cyst bleeding was not described before. Patients known to have large and multiple Tarlov cysts should be monitored in post-partum, as their presence is considered a risk factor. Percutaneous cyst aspiration seems to be an effective and safe treatment to relieve symptoms.

Fatigue in Multiple Sclerosis: A Review of the Exploratory and Therapeutic Potential of Non-Invasive Brain Stimulation

Fatigue is the most commonly reported symptom in patients with multiple sclerosis (MS). It is a worrisome, frequent, and debilitating manifestation that could occur at any time during the course of MS and in all its subtypes. It could engender professional, familial, and socioeconomic consequences and could severely compromise the patients' quality of life. Clinically, the symptom exhibits motor, cognitive, and psychosocial facets. It is also important to differentiate between perceived or subjective self-reported fatigue and fatigability which is an objective measure of decrement in the performance of cognitive or motor tasks. The pathophysiology of MS fatigue is complex, and its management remains a challenge, despite the existing body of literature on this matter. Hence, unraveling its neural mechanisms and developing treatment options that target the latter might constitute a promising field to explore. A PubMed/Medline/Scopus search was conducted to perform this review which aims (a) to reappraise the available electrophysiological studies that explored fatigue in patients with MS with a particular focus on corticospinal excitability measures obtained using transcranial magnetic stimulation and (b) to assess the potential utility of employing neuromodulation (i.e., non-invasive brain stimulation techniques) in this context. A special focus will be put on the role of transcranial direct current stimulation and transcranial magnetic stimulation. We have provided some suggestions that will help overcome the current limitations in upcoming research.

Motor preparation impairment in multiple sclerosis: Evidence from the Bereitschaftspotential in simple and complex motor tasks

OBJECTIVES

Multiple sclerosis (MS) is a chronic inflammatory disease of the central nervous system, characterized by the accumulation of demyelinating lesions and axonal loss over its course. This study aimed to increase current knowledge of motor preparation in this condition, by assessing the two components of the Bereitschaftspotential (BP1 and BP2), also known as the readiness potential.

METHODS

Twelve patients with MS and ten age- and gender-matched healthy controls (HC) were included. Patients' demographic and clinical data were collected. Participants were asked to perform two different tasks, a simple index extension and a Luria sequence. BP1 and BP2 values were obtained from 18 central electroencephalography electrodes and were compared between the two groups.

RESULTS

Compared to HC, patients with MS showed earlier BP1 onset (i.e., longer latency) in almost all the analyzed scalp regions during index extension. This was also observed during the Luria sequence, but only in the centro-parietal regions. As for BP2 latency, no significant difference was noted between groups during either task. With regard to amplitudes, patients with MS had larger BP1 amplitudes in the right fronto-central area during index extension and greater BP1 and BP2 amplitudes in bilateral centro-parietal and left central regions during the Luria task. BP1 latency was also found to be significantly correlated with disease duration and performance on executive function tests (Trail Making Test).

CONCLUSIONS

This study showed, for the first time, changes in the Bereitschaftspotential in patients with MS. These data reflect prolonged movement preparation in this population and may suggest global alteration of the premotor scheme.

Ten Years After SINS: Role of Surgery and Radiotherapy in the Management of Patients With Vertebral Metastases

The objective of the different types of treatments for a spinal metastasis is to provide the best oncological and functional result with the least aggressive side effects. Initially created in 2010 to help clinicians in the management of vertebral metastases, the Spine Instability Neoplastic Score (SINS) has quickly found its place in the decision making and the treatment of patients with metastatic spinal disease. Here we conduct a review of the literature describing the different changes that occurred with the SINS score in the last ten years. After a brief presentation of the spinal metastases’ distribution, with or without spinal cord compression, we present the utility of SINS in the radiological diagnosis and extension of the disease, in addition to its limits, especially for scores ranging between 7 and 12. We take this opportunity to expose the latest advances in surgery and radiotherapy concerning spinal metastases, as well as in palliative care and pain control. We also discuss the reliability of SINS amongst radiologists, radiation oncologists, spine surgeons and spine surgery trainees. Finally, we will present the new SINS-derived predictive scores, biomarkers and artificial intelligence algorithms that allow a multidisciplinary approach for the management of spinal metastases.

The effects of transcranial direct current stimulation on sleep in patients with multiple sclerosis-A pilot study

BACKGROUND

Sleep complaints are commonly reported by patients with multiple sclerosis (PwMS). Several pharmacological and alternative interventions have been tried, but are usually faced by limited efficacy. Hence, exploring other methods such as transcranial direct current stimulation (tDCS), might be of interest. The aim of this study was to assess the effects of bifrontal tDCS on subjective (i.e., Epworth Sleepiness Scale (ESS)) and objective sleep measures (i.e., actigraphy).

METHODS

Seven patients completed the study. Patients randomly received two blocks of five daily sessions each in a crossover design (active and sham, with a washout interval of three weeks). The anode and cathode were placed over the left and right dorsolateral prefrontal cortices, respectively. Sleep assessment included ESS, sleep onset latency, total sleep duration, time in bed, sleep efficiency, waking after sleep onset, and number of awakenings.

RESULTS

Compared to baseline scores (11.14 ± 4.06), significant decrease in ESS was obtained after active intervention (7.86 ± 4.18; p = 0.011), but not after sham intervention (9.57 ± 5.62; p = 0.142). No significant changes were observed with regards to actigraphy measures. Sessions were well tolerated, and no serious side-effects were reported at any time.

CONCLUSION

Bifrontal tDCS resulted in significant improvement in daytime sleepiness, but did not yield any effect on objective sleep measures in PwMS. This discrepency might be explained by the modest association that could exist between objective and subjective sleep measures. In addition, it could be assumed that modulating objective sleep measures would require a larger sample size, more stimulation sessions, or modulation of other cortical areas.

Neurofeedback therapy for the management of multiple sclerosis symptoms: current knowledge and future perspectives

Fatigue is a frequent and debilitating symptom in patients with multiple sclerosis (MS). Affective manifestations are also of high prevalence in this population and can drastically impact the patients' functioning. A considerable proportion of patients with MS suffer from cognitive deficits affecting general and social cognitive domains. In addition, pain in MS is commonly observed in neurology wards, could be of different types, and may result from or be exacerbated by other MS comorbidities. These complaints tend to cluster together in some patients and seem to have a complex pathophysiology and a challenging management. Exploring the effects of new interventions could improve these outcomes and ameliorate the patients' quality of life. Neurofeedback (NFB) might have its place in this context by enhancing or reducing the activity of some regions in specific electroencephalographic bands (i.e., theta, alpha, beta, sensorimotor rhythm). This work briefly revisits the principles of NFB and its application. The published data are scarce and heterogeneous yet suggest preliminary evidence on the potential utility of NFB in patients with MS (i.e., depression, fatigue, cognitive deficits and pain). NFB is simple to adapt and easy to coach, and its place in the management of MS symptoms merits further investigations. Comparing different NFB protocols (i.e., cortical target, specific rhythm, session duration and number) and performing a comprehensive evaluation could help developing and optimizing interventions targeting specific symptoms. These aspects could also open the way for the association of this technique with other approaches (i.e., brain stimulation, cognitive rehabilitation, exercise training, psychotherapies) that have proved their worth in some MS domains.

Autoimmune Brainstem Encephalitis: An Illustrative Case and a Review of the Literature

Autoimmune brainstem encephalitis (BSE) is a rare neurological condition with a wide range of underlying etiologies. It can be subdivided into two broad groups: a primary inflammatory disease of the central nervous system (CNS) or a brainstem disorder secondary to systemic diseases where the CNS is only one of many affected organs. Symptoms range from mild to life-threatening manifestations. Most cases respond well to immunotherapy. Therefore, broad and in-depth knowledge of the various inflammatory disorders that target the brainstem is essential for guiding the diagnostic approach and assisting in early initiation of appropriate therapy. We herein report on a case of BSE and provide an overview of the various causes of autoimmune BSE with an emphasis on the clinical manifestations and diagnostic approach.

Repetitive transcranial magnetic stimulation for neuropathic pain: a randomized multicentre sham-controlled trial

Repetitive transcranial magnetic stimulation (rTMS) has been proposed to treat neuropathic pain but the quality of evidence remains low. We aimed to assess the efficacy and safety of neuronavigated rTMS to the motor cortex (M1) or dorsolateral prefrontal cortex (DLPFC) in neuropathic pain over 25 weeks. We did a randomised double-blind, placebo-controlled trial at four outpatient clinics in France. Patients aged 18-75 years with peripheral neuropathic pain were randomly assigned in a 1:1 ratio to M1 or DLPFC-rTMS and re-randomised in a 2:1 ratio to active or sham rTMS (10 Hz, 3000 pulses/session, 15 sessions over 22 weeks). Patients and investigators were blind to treatment allocation. The primary endpoint was the comparison between active M1-rTMS, active DLPCF-rTMS and sham-rTMS for the change over the course of 25 weeks (group by time interaction) in average pain intensity (from 0 no pain to 10 maximal pain) on the Brief Pain Inventory (BPI), using a mixed model repeated measures analysis in patients who received at least one rTMS session (modified ITT population). Secondary outcomes included other measures of pain intensity and relief, sensory and affective dimensions of pain, quality of pain, self reported pain intensity and fatigue (patients diary), patient and clinician global impression of change (PGIC, CGIC), quality of life, sleep, mood and catastrophizing. This study is registered with ClinicalTrials.gov NCT02010281. A total of 152 patients were randomised and 149 received treatment (49 for M1; 52 for DLPFC; 48 for sham). M1-rTMS reduced pain intensity versus sham-rTMS (estimate for group x session interaction: -0.048 ± 0.02; 95% CI: -0.09 to -0.01; p = 0.01). DLPFC-rTMS was not better than sham (estimate: -0.003 ± 0.01; 95% CI:-0.04 to 0.03, p = 0.9). M1-rRMS, but not DLPFC-rTMS, was also superior to sham-rTMS on pain relief, sensory dimenson of pain, self reported pain intensity and fatigue, PGIC and CGIC. There were no effect on quality of pain, mood, sleep and quality of life as all groups improved similarly over time. Headache was the most common side effect and occurred in 17 (34.7%), 23 (44.2%) and 13 (27.1%) patients from M1, DLPFC and sham groups respectively (p = 0.2). Our results support the clinical relevance of M1-rTMS, but not of DLPFC-rTMS, for peripheral neuropathic pain with an excellent safety profile.

The value of sensory nerve conduction studies in the diagnosis of Guillain-Barré syndrome

Electrophysiology plays a determinant role in Guillain-Barré syndrome (GBS) diagnosis, classification, and prognostication. However, traditional electrodiagnostic (EDX) criteria for GBS rely on motor nerve conduction studies (NCS) and are suboptimal early in the course of the disease or in the setting of GBS variants. Sensory nerve conduction studies, including the sural-sparing pattern and the sensory ratio are not yet included in EDX criteria despite their well-established role in GBS diagnosis. The aim of this review is to discuss the diagnostic value of sensory NCS in GBS, their role in establishing the diagnosis and predicting the outcome according to the various subtypes of the disease.

Case Report: Multimodal Functional and Structural Evaluation Combining Pre-operative nTMS Mapping and Neuroimaging With Intraoperative CT-Scan and Brain Shift Correction for Brain Tumor Surgical Resection

Background: Maximum safe resection of infiltrative brain tumors in eloquent area is the primary objective in surgical neuro-oncology. This goal can be achieved with direct electrical stimulation (DES) to perform a functional mapping of the brain in patients awake intraoperatively. When awake surgery is not possible, we propose a pipeline procedure that combines advanced techniques aiming at performing a dissection that respects the anatomo-functional connectivity of the peritumoral region. This procedure can benefit from intraoperative monitoring with computerized tomography scan (iCT-scan) and brain shift correction. Associated with this intraoperative monitoring, the additional value of preoperative investigation combining brain mapping by navigated transcranial magnetic stimulation (nTMS) with various neuroimaging modalities (tractography and resting state functional MRI) has not yet been reported. Case Report: A 42-year-old left-handed man had increased intracranial pressure (IICP), left hand muscle deficit, and dysarthria, related to an infiltrative tumor of the right frontal lobe with large mass effect and circumscribed contrast enhancement in motor and premotor cortical areas. Spectroscopy profile and intratumoral calcifications on CT-scan suggested an WHO grade III glioma, later confirmed by histology. The aforementioned surgical procedure was considered, since standard awake surgery was not appropriate for this patient. In preoperative time, nTMS mapping of motor function (deltoid, first interosseous, and tibialis anterior muscles) was performed, combined with magnetic resonance imaging (MRI)-based tractography reconstruction of 6 neural tracts (arcuate, corticospinal, inferior fronto-occipital, uncinate and superior and inferior longitudinal fasciculi) and resting-state functional MRI connectivity (rs-fMRI) of sensorimotor and language networks. In intraoperative time, DES mapping was performed with motor evoked response recording and tumor resection was optimized using non-rigid image transformation of the preoperative data (nTMS, tractography, and rs-fMRI) to iCT data. Image guidance was updated with correction for brain shift and tissue deformation using biomechanical modeling taking into account brain elastic properties. This correction was done at crucial surgical steps, i.e., when tumor bulged through the craniotomy after dura mater opening and when approaching the presumed eloquent brain regions. This procedure allowed a total resection of the tumor region with contrast enhancement as well as a complete regression of IICP and dysarthria. Hand paresis remained stable with no additional deficit. Postoperative nTMS mapping confirmed the good functional outcome. Conclusion: This case report and technical note highlights the value of preoperative functional evaluation by nTMS updated intraoperatively with correction of brain deformation by iCT. This multimodal approach may become the optimized technique of reference for patients with brain tumors in eloquent areas that are unsuitable for awake brain surgery.

Effects of Transcranial Direct Current Stimulation on Information Processing Speed, Working Memory, Attention, and Social Cognition in Multiple Sclerosis

Multiple Sclerosis (MS) is a chronic inflammatory disease of the central nervous system. Cognitive impairment occurs in 40-65% of patients and could drastically affect their quality of life. Deficits could involve general cognition (e.g., attention and working memory) as well as social cognition. Transcranial direct current stimulation (tDCS), is a novel brain stimulation technique that has been assessed in the context of several neuropsychiatric symptoms, including those described in the context of MS. However, very rare trials have assessed tDCS effects on general cognition in MS, and none has tackled social cognition. The aim of this work was to assess tDCS effects on general and social cognition in MS. Eleven right-handed patients with MS received two blocks (bifrontal tDCS and sham, 2 mA, 20 min, anode/cathode over left/right prefrontal cortex) of 5 daily stimulations separated by a 3-week washout interval. Working memory and attention were, respectively, measured using N-Back Test (0-Back, 1-Back, and 2-Back) and Symbol Digit Modalities Test (SDMT) at the first and fifth day of each block and 1 week later. Social cognition was evaluated using Faux Pas Test and Eyes Test at baseline and 1 week after each block. Interestingly, accuracy of 1-Back test improved following sham but not active bifrontal tDCS. Therefore, active bifrontal tDCS could have impaired working memory via cathodal stimulation of the right prefrontal cortex. No significant tDCS effects were observed on social cognitive measures and SDMT. Admitting the small sample size and the learning (practice) effect that might arise from the repetitive administration of each task, the current results should be considered as preliminary and further investigations in larger patient samples are needed to gain a closer understanding of tDCS effects on cognition in MS.

Tremor in Multiple Sclerosis-An Overview and Future Perspectives

Tremor is an important and common symptom in patients with multiple sclerosis (MS). It constituted one of the three core features of MS triad described by Charcot in the last century. Tremor could have a drastic impact on patients' quality of life. This paper provides an overview of tremor in MS and future perspectives with a particular emphasis on its epidemiology (prevalence: 25-58%), clinical characteristics (i.e., large amplitude 2.5-7 Hz predominantly postural or intention tremor vs. exaggerated physiological tremor vs. pseudo-rhythmic activity arising from cerebellar dysfunction vs. psychogenic tremor), pathophysiological mechanisms (potential implication of cerebellum, cerebello-thalamo-cortical pathways, basal ganglia, and brainstem), assessment modalities (e.g., tremor rating scales, Stewart-Holmes maneuver, visual tracking, digitized spirography and accelerometric techniques, accelerometry-electromyography coupling), and therapeutic options (i.e., including pharmacological agents, botulinum toxin A injections; deep brain stimulation or thalamotomy reserved for severe, disabling, or pharmaco-resistant tremors). Some suggestions are provided to help overcome the unmet needs and guide future therapeutic and diagnostic studies in this complex disorder.

Paroxysmal Symptoms in Multiple Sclerosis-A Review of the Literature

Paroxysmal symptoms are well-recognized manifestations of multiple sclerosis (MS). These are characterized by multiple, brief, sudden onset, and stereotyped episodes. They manifest as motor, sensory, visual, brainstem, and autonomic symptoms. When occurring in the setting of an established MS, the diagnosis is relatively straightforward. Conversely, the diagnosis is significantly more challenging when they occur as the initial manifestation of MS. The aim of this review is to summarize the various forms of paroxysmal symptoms reported in MS, with emphasis on the clinical features, radiological findings and treatment options.

Effects of Transcranial Direct Current Stimulation on Hand Dexterity in Multiple Sclerosis: A Design for a Randomized Controlled Trial

BACKGROUND

Cerebellar and motor tracts are frequently impaired in multiple sclerosis (MS). Altered hand dexterity constitutes a challenge in clinical practice, since medical treatment shows very limited benefits in this domain. Cerebellar control is made via several cerebellocortical pathways, of which the most studied one links the cerebellum to the contralateral motor cortex via the contralateral ventro-intermediate nucleus of the thalamus influencing the corticospinal outputs. Modulating the activity of the cerebellum or of the motor cortex could be of help.

METHOD

The main interest here is to evaluate the efficacy of transcranial direct current stimulation (tDCS), a noninvasive brain stimulation technique, in treating altered dexterity in MS. Forty-eight patients will be recruited in a randomized, double-blind, sham-controlled, and crossover study. They will randomly undergo one of the three interventions: anodal tDCS over the primary motor area, cathodal tDCS over the cerebellum, or sham. Each block consists of five consecutive daily sessions with direct current (2 mA), lasting 20 min each. The primary outcome will be the improvement in manual dexterity according to the change in the time required to complete the nine-hole pegboard task. Secondary outcomes will include fatigue, pain, spasticity, and mood. Patients' safety and satisfaction will be rated.

DISCUSSION

Due to its cost-effective, safe, and easy-to-use profile, motor or cerebellar tDCS may constitute a potential tool that might improve dexterity in MS patients and therefore ameliorate their quality of life.

Bifrontal transcranial direct current stimulation modulates fatigue in multiple sclerosis: a randomized sham-controlled study

Fatigue is a frequent and debilitating symptom in patients with central nervous system diseases. Up to 90% of patients with multiple sclerosis (MS) suffer from fatigue that drastically affects the quality of life. MS patients also complain of anxiety and depressive symptoms and these three manifestations tend to cluster together in this clinical population. The objective of this work was to assess the effects of transcranial direct stimulation (tDCS), a noninvasive brain stimulation technique, on fatigue as well as anxiety and depressive symptoms. Eleven fatigued MS patients randomly received two blocks (active and sham tDCS) of five consecutive daily sessions of bifrontal tDCS (anode/cathode over the left/right prefrontal cortices, respectively) in a crossover manner, separated by a 3-week washout interval. Evaluation took place at day 1, day 5 (right after each block) and 1 week later. Active but not sham tDCS resulted in a significant improvement of fatigue at day 5 (p < 0.05), an effect that seems to last at least 1 week following the stimulation (p = 0.05). Active tDCS also significantly improved anxiety symptoms, but the effect emerged 1 week later (p < 0.05). No significant effects were obtained regarding depression (p > 0.05). Bifrontal tDCS seems to modulate fatigue in PwMS. The observed anxiolytic effects could constitute delayed after effects of tDCS or might be mediated by fatigue improvement. These findings merit to be addressed in large-scale controlled trials.

Deciphering the neural underpinnings of alexithymia in multiple sclerosis

OBJECTIVES

Alexithymia is a personality construct that could occur in up to 53 % of patients with multiple sclerosis (MS). It entails difficulties in identifying and describing one's feelings and an externally oriented thinking. The current work aims to assess the neural underpinnings of alexithymia in this population.

METHODS

Forty-five patients with MS filled in the Toronto Alexithymia Scale (n = 17 with high alexithymia and n = 28 with low alexithymia). Brain magnetic resonance imaging was obtained for each patient and a morphometry algorithm (MorphoBox) was applied to calculate regional brain volumes. All patients underwent a clinical and neuropsychological evaluation which included measures for anxiety, depression, fatigue, daytime sleepiness, and basic and social cognition.

RESULTS

Compared to patients with low alexithymia, patients with high alexithymia had significantly higher fatigue and depression ratings, and lower empathy scores. In addition, they had lower volumes of corpus callosum, deep white matter, pallidum bilaterally, and left thalamus. In the whole cohort, alexithymia scores were inversely correlated with gray matter (thalamus and pallidum bilaterally) and white matter volumes (corpus callosum and bilateral deep white matter) after controlling for covariates (ps<0.05).

CONCLUSION

This study offers insights on the neuropsychological and neural substrates of alexithymia in MS. The current findings are consistent with alexithymia reports in other clinical populations, and suggest an association between alexithymia and atrophy of thalami, pallidum, corpus callosum and deep white matter in MS. Further research is needed to enhance the understanding of alexithymia mechanisms in this clinical context.

Could Transcranial Direct Current Stimulation Join the Therapeutic Armamentarium in Obsessive-Compulsive Disorder?

Obsessive-compulsive disorder (OCD) is a mental disorder that can affect around 1-3% of individuals [...].

Cathodal Transcranial Direct Current Stimulation of the Occipital cortex in Episodic Migraine: A Randomized Sham-Controlled Crossover Study

Three consecutive daily sessions of cathodal transcranial direct current stimulation (tDCS) was sufficient to show a significant decrease in headache duration and intensity as well as tablets consumption, in patients suffering from episodic migraine.

BACKGROUND

Migraine prophylaxis is recommended in patients with frequent and/or intense headaches, but poor tolerability and lack of efficacy of preventive drugs are common in clinical practice. Hence, new prophylactic strategies are needed.

OBJECTIVE

The aim of this study was to evaluate the efficacy of tDCS in terms of migraine prophylaxis.

METHODS

This was a double blind and sham-controlled trial. Forty-two migraine patients were randomly assigned in a crossover design to receive three consecutive daily sessions of both sham and cathodal tDCS stimulation (2.0 mA, 20 min) over the occipital cortex of the dominant side of the migraine pain (O1/O2). Migraine duration and intensity, number of analgesic tablets, and number of headache-free days (where no headache abortive medications are taken) were recorded one week before and two weeks after treatment. A washout period of one week was allowed before crossing to the other treatment arm.

RESULTS

Relative to sham, cathodal stimulation was associated with a significant reduction in the number of headache days, tablets consumption, and pain intensity; and a significant increase in the number of headache-free days. These beneficial effects were sustained over two weeks. No serious side effects were observed, and the procedure was well tolerated.

CONCLUSION

Based on these findings, cathodal tDCS applied to the occipital cortex seems to be an effective and well tolerated alternative to pharmacotherapy in patients with episodic migraine.

Precise finger somatotopy revealed by focal motor cortex injury

BACKGROUND

Somatotopy is considered the hallmark of the primary motor cortex. While this is fundamentally true for the major body parts (head, upper and lower extremities), evidence supporting the existence of within-limb somatotopy is scarce.

METHOD

We report a young man presenting recurrent ischemic strokes with selective finger weakness in whom serial motor cortex mapping procedures were performed.

RESULT

Following the first stroke, which largely spared the motor cortex, motor mapping displayed overlap of the motor representations of the hand muscles. The second focal stroke, affecting the lateral part of the hand knob, resulted in selective loss of the first dorsal interosseous muscle motor evoked potentials while sparing those of the adductor digiti minimi muscle. This observation is in apparent contradiction with the first mapping results that suggested complete overlap of motor representations.

DISCUSSION

Our mapping results provide evidence for the existence of very precise within-limb somatotopy and confirm the proposed homuncular order, whereby lateral fingers are represented laterally and medial fingers medially. The discrepancy between the initial and subsequent mapping results is discussed in light of functional organization of the primary motor cortex.

Longitudinal Extensive Transverse Myelitis in an Immunocompetent Older Individual-A Rare Complication of Varicella-Zoster Virus Reactivation

Varicella-zoster virus (VZV) is a human neurotropic herpes virus that causes chickenpox in children. After becoming latent in dorsal root ganglia, it can reactivate to cause dermatological manifestations, the most common one being shingles or herpes zoster. Severe neurologic dysfunctions can occur in immunocompromised patients such as encephalitis, meningitis, myelitis and neuropathy. Longitudinal extensive transverse myelitis (LETM) is an unusual neurological complication mainly described in immunocompromised patients, with very few cases described in immunocompetent ones. We hereby report a case of VZV-induced LETM in an immunocompetent older adult—a situation rarely described in the literature. LETM is a rare complication of VZV and its pathogenesis; therapeutic interventions and prognosis are far from being fully clarified. However, a prompt diagnosis is needed to allow a rapid initialization of treatment and ensure a better outcome. Although the therapeutic lines are not clear, immunosuppressive agents may have their place in cases of unsuccessful results and/or relapses following acyclovir coupled with a well conducted methylprednisolone therapy. Further studies are highly needed to improve the current understanding of the disease course and mechanisms, and to optimize therapeutic strategies.

Coaching of lifestyle recommendations improves sensory neurophysiological parameters in neuropathies related to glycemic disorder or metabolic syndrome. A pilot study

OBJECTIVES

Metabolic abnormalities, such as, glycemic disorders and metabolic syndrome (GDMS) are one of the main causes of peripheral neuropathies. The objective of this study was to evaluate the impact of adding specific coaching care (CC) to standard care (SC) of therapeutic education based on lifestyle recommendations for neuropathies associated with GDMS.

METHODS

This prospective randomized study included two groups of four patients (SC vs. CC) with examiners blinded to group allocation. The SC group had one day of therapeutic education on lifestyle measures (physical activity and diet recommendations) followed by only one phone call of reinforcement. The CC group received an additional weekly phone call of reinforcement for 3 months. Clinical, biological and neurophysiological variables were compared between the two groups at baseline and for the percentage of change at 3 months.

RESULTS

All patients (4 men and 4 women) had diabetes or pre-diabetes, which was associated with metabolic syndrome in 5 cases. There was no difference on any variable at baseline, but at 3 months, Mann-Whitney test showed a difference (P=0.0008) between the two groups regarding the sensory neurophysiological variable, which deteriorated in the SC group (median: -6.0%) and improved in the CC group (median: +12.4%). No significant difference was observed between the two groups for the other variables at 3 months.

CONCLUSION

The weekly coaching of recommendations for lifestyle measures over a period of three months allows an improvement of GDMS neuropathies, at least in terms of sensory aspects, as evidenced by neurophysiological assessments.

The place of transcranial direct current stimulation in the management of multiple sclerosis-related symptoms

Multiple sclerosis (MS) is an autoimmune disease of the central nervous system, characterized by chronic inflammation, demyelination, synaptopathy and neurodegeneration. Patients may exhibit sensory, motor, cognitive, emotional and behavioral symptoms throughout their disease process. Nowadays, the challenge is to find optimal treatment for MS symptoms, especially that available pharmacological interventions are faced by modest therapeutic outcomes and numerous side effects. Thus, finding alternative strategies might be of help in this context. The aim of this report is to visit the effects of transcranial direct current stimulation - a noninvasive brain stimulation technique - in the context of MS symptoms, namely fatigue, cognitive deficits, psychiatric complaints, neuropathic pain and some sensorimotor manifestations.

Interhermispheric inhibition predicts anxiety levels in multiple sclerosis: A corticospinal excitability study

BACKGROUND

Depression and anxiety stand among the most frequent and debilitating complaints in multiple sclerosis (MS) patients. Understanding their neurophysiological correlates might improve their management. To date, no single study has addressed this issue.

METHOD

Patients completed the Hospital Anxiety and Depression Scale (HADS). Transcranial magnetic stimulation (TMS) was performed to obtain the following corticospinal excitability measures: resting motor threshold, short-interval intracortical inhibition and facilitation, cortical silent period and interhemispheric inhibition (IHI). Anxiety and depression scores were the primary outcomes in the univariate analysis. When obtaining significant associations between anxiety/depression and TMS measures, a multivariate analysis was performed using stepwise linear regression with anxiety and depression scores employed separately as dependent variables and TMS measures, clinical and sociodemographic data as independent variables. Due to the small sample size and the large number of studied variables, only variables with p values <0.05 in the univariate analysis were included in the multivariate analysis.

RESULTS

Fifty patients completed the study (n = 24 women). Their mean age was 51.82 ± 12.72 years. Mean depression score was 6.08 ± 3.66. Mean anxiety score was 5.82 ± 3.42. A significant association was found between anxiety and IHI (p < 0.05), fatigue (p < 0.05), depression (p < 0.05), and female gender (p < 0.05). Stepwise linear regression analysis was performed and IHI values explained 9.10% of variance in anxiety levels (standardized β: 0.31; p < 0.01) when controlling for remaining variables. As for depression, it did not significantly correlate with any TMS measures.

CONCLUSION

The results highlight the relationship between anxiety and callosal transfer as reflected by IHI values. The current findings are consistent with previous works assessing healthy participants and patients with social anxiety disorders. Compared to MS patients with aberrant callosal transfer (suggested by low IHI values), those exhibiting a relatively more efficient one (reflected by high IHI values) seem to have higher anxiety scores, a finding that merits further assessment.

Disentangling the Neural Basis of Cognitive Behavioral Therapy in Psychiatric Disorders: A Focus on Depression

Background: Major depressive disorder (MDD) stands among the most frequent psychiatric disorders. Cognitive behavioral therapy (CBT) has been shown to be effective for treating depression, yet its neural mechanisms of action are not well elucidated. The objective of this work is to assess the available neuroimaging studies exploring CBT’s effects in adult patients with MDD. Methods: Computerized databases were consulted till April 2018 and a research was conducted according to PRISMA guidelines in order to identify original research articles published at any time in English and French languages on this topic. Results: Seventeen studies were identified. Only one study was randomized comparing CBT to pharmacological interventions, and none included an effective control. Following CBT, changes occurred in cerebral areas that are part of the fronto-limbic system, namely the cingulate cortex, prefrontal cortex and amygdala-hippocampal complex. However, the pattern of activation and connectivity in these areas varied across the studies. Conclusion: A considerable heterogeneity exists with regard to study design, adapted CBT type and intensity, and employed neuroimaging paradigms, all of which may partly explain the difference in studies’ outcomes. The lack of randomization and effective controls in most of them makes it difficult to draw formal conclusion whether the observed effects are CBT mediated or due to spontaneous recovery. Despite the observed inconsistencies and dearth of data, CBT appears to exert its anti-depressant effects mainly by modulating the function of affective and cognitive networks devoted to emotions generation and control, respectively. This concept remains to be validated in large scale randomized controlled trials.

The ulnar ratio as a sensitive and specific marker of acute inflammatory demyelinating polyneuropathy

OBJECTIVES

To explore the value of a novel sensory criterion, the ulnar ratio - defined as the SNAP amplitude of the palmar cutaneous (pUN) over that of the dorsal branch (dUN) of the ulnar nerve - as a predictor of Acute Inflammatory Demyelinating Polyneuropathy (AIDP).

METHODS

We prospectively included 22 patients with AIDP, 20 patients with diabetic peripheral neuropathy (DPN), and 18 controls. Eligible subjects underwent nerve conduction studies including, among others, the dUN, pUN, and sural nerve.

RESULTS

A sural sparing pattern was found in 72% of AIDP cases. The ulnar ratio was significantly lower in patients with AIDP compared to those with DPN or controls. The ROC curve area to discriminate AIDP (versus controls and diabetics together) was higher with the ulnar ratio and pUN compared to dUN. An ulnar ratio ≥ 0.78 seems to be the best threshold to rule out the diagnosis of AIDP, with a specificity of 100% and a sensitivity of 87%. The ulnar ratio was equally reliable in the subgroup of patients presenting within a week of symptoms onset.

CONCLUSION

The ulnar ratio is a highly sensitive and specific marker of AIDP and can help confirm the diagnosis when direct signs of demyelination are lacking.

SIGNIFICANCE

Incorporating specific sensory abnormalities, such as the ulnar ratio, in the electrodiagnostic criteria of AIDP could enhance their reliability.

Is there a link between inflammation and fatigue in multiple sclerosis?

Purpose

Among autoimmune diseases of the central nervous system stands multiple sclerosis (MS), which is characterized by demyelination, synaptopathy, and neurodegeneration. MS fatigue can affect up to 90% of patients and be very disabling, with a drastic impact on their quality of life. To date, the evaluation of MS fatigue has relied mainly on subjective scales, and actual therapeutic interventions are challenged by modest efficacy and numerous undesirable effects. Therefore, finding biomarkers of MS fatigue might help in optimizing evaluation and treatment strategies. The main objective here was to assess the relationship between MS fatigue and inflammatory or other immunomediated markers.

Methods

Research was conducted according to PRISMA guidelines. Computerized databases (ie, PubMed/Medline and Scopus) were consulted till February 2018 aiming to identify articles that addressed inflammation and MS fatigue. Studies in English and French published at any time were considered.

Results

A total of 27 studies matched the research criteria. Inconsistency existed regarding the relationship between fatigue and the orexin A system, hypothalamus–pituitary–adrenal axis, and cerebrospinal fluid inflammatory markers. As for peripheral markers, although there was scarcity in the available data, serum proinflammatory cytokines (ie, IL6, TNFα, and IFNγ) seem to be associated with MS fatigue. Finally, no link was found between MS fatigue and T-cell populations (ie, CD3⁺CD4⁺ T lymphocytes, regulatory T cells) or other peripheral markers of inflammation (ie, CRP, erythrocyte-sedimentation rate, soluble ICAM1).

Conclusion

Future large-scale studies would benefit from comparing the relationship between fatigue and immune measures in patients with different disease phenotypes with and without disease-modifying drugs. With the subjective nature of fatigue scales, finding objective biomarkers for fatigue would be of great help.

High-Frequency Neuronavigated rTMS in Auditory Verbal Hallucinations: A Pilot Double-Blind Controlled Study in Patients With Schizophrenia

INTRODUCTION

Despite extensive testing, the efficacy of low-frequency (1 Hz) repetitive transcranial magnetic stimulation (rTMS) of temporo-parietal targets for the treatment of auditory verbal hallucinations (AVH) in patients with schizophrenia is still controversial, but promising results have been reported with both high-frequency and neuronavigated rTMS. Here, we report a double-blind sham-controlled study to assess the efficacy of high-frequency (20 Hz) rTMS applied over a precise anatomical site in the left temporal region using neuronavigation.

METHODS

Fifty-nine of 74 randomized patients with schizophrenia or schizoaffective disorders (DSM-IV R) were treated with rTMS or sham treatment and fully evaluated over 4 weeks. The rTMS target was determined by morphological MRI at the crossing between the projection of the ascending branch of the left lateral sulcus and the superior temporal sulcus (STS).

RESULTS

The primary outcome was response to treatment, defined as a 30% decrease of the Auditory Hallucinations Rating Scale (AHRS) frequency item, observed at 2 successive evaluations. While there was no difference in primary outcome between the treatment groups, the percentages of patients showing a decrease of more than 30% of AHRS score (secondary outcome) did differ between the active (34.6%) and sham groups (9.1%) (P = .016) at day 14.

DISCUSSION

This controlled study reports negative results on the primary outcome but demonstrates a transient effect of 20 Hz rTMS guided by neuronavigation and targeted on an accurate anatomical site for the treatment of AVHs in schizophrenia patients.

The evaluation of depression in multiple sclerosis using the newly proposed Multiple Sclerosis Depression Rating Scale

Fatigue and depression are frequent symptoms in multiple sclerosis (MS). Both are overlapping and shadowing each other and may impair the quality of life. For detection of depression symptoms in MS, the Multiple Sclerosis Depression Rating Scale (MSDRS) has been proposed recently. Here, we compare the performance of MSDRS in MS patients with and without fatigue to that of established rating scales, i.e. Hospital Anxiety and Depression Scale and Beck Depression Inventory. Twenty-nine MS patients were screened for fatigue and depression symptoms. Patients with fatigue showed significantly higher depression scores compared to patients without fatigue, whereas the number of depressed patients did not differ between the two groups. MSDRS seems to have higher sensitivity to detect severe depression than established rating scales. However, one should keep in mind that such a finding might be due to an increase in false positive cases when using MSDRS. Implementing this scale in future studies might be of help to enhance the understanding of its potential utility.