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Contains fulltext : 292380.pdf (Publisher’s version ) (Closed access) OBJECTIVE: To clarify the significance of any form of myoclonus in comatose patients after cardiac arrest with rhythmic and periodic EEG patterns (RPPs) by analyzing associations between myoclonus and EEG pattern, response to anti-seizure medication and neurological outcome. DESIGN: Post hoc analysis of the prospective randomized Treatment of ELectroencephalographic STatus Epilepticus After Cardiopulmonary Resuscitation (TELSTAR) trial. SETTING: Eleven ICUs in the Netherlands and Belgium. PATIENTS: One hundred and fifty-seven adult comatose post-cardiac arrest patients with RPPs on continuous EEG monitoring. INTERVENTIONS: Anti-seizure medication vs no anti-seizure medication in addition to standard care. MEASUREMENTS AND MAIN RESULTS: Of 157 patients, 98 (63%) had myoclonus at inclusion. Myoclonus was not associated with one specific RPP type. However, myoclonus was associated with a smaller probability of a continuous EEG background pattern (48% in patients with vs 75% without myoclonus, odds ratio (OR) 0.31; 95% confidence interval (CI) 0.16-0.64) and earlier onset of RPPs (24% vs 9% within 24 hours after cardiac arrest, OR 3.86;95% CI 1.64-9.11). Myoclonus was associated with poor outcome at three months, but not invariably so (poor neurological outcome in 96% vs 82%, p = 0.004). Anti-seizure medication did not improve outcome, regardless of myoclonus presence (6% good outcome in the intervention group vs 2% in the control group, OR 0.33; 95% CI 0.03-3.32). CONCLUSIONS: Myoclonus in comatose patients after cardiac arrest with RPPs is associated with poor outcome and discontinuous or suppressed EEG. However, presence of myoclonus does not interact with the effects of anti-seizure medication and cannot predict a poor outcome without false positives.

Objective: A role of the motor cortex in tremor generation in essential tremor (ET) is assumed, yet the directionality of corticomuscular coupling is unknown. Our aim is to clarify the role of the motor cortex. To this end we also study ‘familial cortical myoclonic tremor with epilepsy’ (FCMTE) and slow repetitive voluntary movements with a known cortical drive. Methods: Directionality of corticomuscular coupling (EEG-EMG) was studied with renormalized partial directed coherence (rPDC) during tremor in 25 ET patients, 25 healthy controls (mimicked) and in seven FCMTE patients; and during a self-paced 2 Hz task in eight ET patients and seven healthy controls. Results: Efferent coupling around tremor frequency was seen in 33% of ET patients, 45.5% of healthy controls, all FCMTE patients, and, around 2 Hz, in all ET patients and all healthy controls. Ascending coupling, seen in the majority of all participants, was weaker in ET than in healthy controls around 5–6 Hz. Conclusions: Possible explanations are that tremor in ET results from faulty subcortical output bypassing the motor cortex; rate-dependent transmission similar to generation of rhythmic movements; and/or faulty feedforward mechanism resulting from decreased afferent (sensory) coupling. Significance: A linear cortical drive is lacking in the majority of ET patients.

Background In patients after cardiac arrest (CA), EEG reactivity (EEG-R) is proposed as a prognostic marker. However, no clear guidelines exist on how to test EEG-R and definitions are unspecific. Therefore, we aimed at forming international consensus regarding a stimulus protocol for EEG-R testing and the interpretation of EEG-R in daily clinical care. Methods We invited 30 international experts on EEG in patients after CA for participation in a two round Delphi study. Consensus was defined as ≥75% agreement, 66–75% agreement was included as recommendation. Results In the first round 24 experts participated (80% response rate) of whom 22 finished the second round (8% drop-out). Consensus was reached on several parts of the stimulus protocol: Clapping, calling out the patient’s name and nail bed pressure should be executed and each stimulus at least three times with recommended duration of at least 5 s. The patient should not be stimulated before EEG-R testing and information on sedation/analgesics should be provided. The consensus definition of EEG-R is “A reproducible change in the EEG in response to stimulation” and appearance of muscle-, movement- and eye blink artefacts, spinal movements and electrographic seizure induction do not qualify as reactive. Almost all respondents agreed that this consensus protocol should also be used in comatose patients with other etiologies. Conclusion This international consensus statement on EEG-R in patients after CA can be regarded as starting point. At the moment evidence is limited and our study can provide best-practice guidance in patients after CA as well as other comatose patients.

Introduction: Cerebellar circuits are hypothesized to play a central role in the pathogenesis of essential tremor. Rhythmic finger tapping is known to strongly engage the cerebellar motor circuitry. We characterize cerebellar and, more specifically, dentate nucleus function, and neural correlates of cerebellar output in essential tremor during rhythmic finger tapping employing functional MRI.Methods: Thirty-one propranolol-sensitive essential tremor patients with upper limb tremor and 29 healthy controls were measured. T2*-weighted EPI sequences were acquired. The task consisted of alternating rest and finger tapping blocks. A whole-brain and region-of-interest analysis was performed, the latter focusing on the cerebellar cortex, dentate nucleus and inferior olive nucleus. Activations were also related to tremor severity.Results: In patients, dentate activation correlated positively with tremor severity as measured by the tremor rating scale part A. Patients had reduced activation in widespread cerebellar cortical regions, and additionally in the inferior olive nucleus, and parietal and frontal cortex, compared to controls.Conclusion: The increase in dentate activation with tremor severity supports involvement of the dentate nucleus in essential tremor. Cortical and cerebellar changes during a motor timing task in essential tremor might point to widespread changes in cerebellar output in essential tremor. (c) 2015 Elsevier Ltd. All rights reserved.

Introduction: We investigated the relation between changes in clinician-based and patient-based measures of tremor severity, within the Fahn-Tolosa-Marin Tremor Rating Scale (IRS) and Visual Analogue Scale (VAS) in essential tremor patients.Methods: Thirty-seven patients were assessed twice: on- and off-medication. Clinician-based, objective TRS assessments, consisting of part A (postures/movements) and part B (tremor-inducing tasks) were conducted by a blinded assessor using video-tapes. Patients completed TRS part C (limitations in activities of daily life) and indicated subjective tremor severity using VAS.Results: Patients' total TRS and VAS scores improved on-medication (both p Discussion: We found no correlation between changes in clinician-based TRS-A, and patient-based measures TRS-C or VAS scores, and a weak correlation between clinician-based TRS-B and VAS scores. The limited correlations between changes in clinician-based and patient-based measures of tremor severity suggest that the different scales measure different aspects of tremor severity and support the additional use of subjective patient-based assessments in clinical practice and clinical trials. (C) 2015 Elsevier Ltd. All rights reserved.

Essential tremor (ET) presumably has a cerebellar origin. Imaging studies showed various cerebellar and also cortical structural changes. A number of pathology studies indicated cerebellar Purkinje cell pathology. ET is a heterogeneous disorder, possibly indicating different underlying disease mechanisms. Familial cortical myoclonic tremor with epilepsy (FCMTE), with evident Purkinje cell degeneration, can be an ET mimic. Here, we investigate whole brain and, more specifically, cerebellar morphological changes in hereditary ET, FCMTE, and healthy controls. Anatomical magnetic resonance images were preprocessed using voxel-based morphometry. Study 1 included voxel-wise comparisons of 36 familial, propranolol-sensitive ET patients, with subgroup analysis on age at onset and head tremor, and 30 healthy controls. Study 2 included voxel-wise comparisons in another nine ET patients, eight FCMTE patients, and nine healthy controls. Study 3 compared total cerebellar volume between 45 ET patients, 8 FCTME patients, and 39 controls. In our large sample of selected hereditary ET patients and ET subgroups, no local atrophy was observed compared to healthy controls or FCMTE. In ET patients with head tremor, a volume increase in cortical motor regions was observed. In FCMTE, a decrease in total cerebellar volume and in local cerebellar gray matter was observed compared to healthy controls and ET patients. The current study did not find local atrophy, specifically not in the cerebellum in hereditary ET, contrary to FCMTE. Volume increase of cortical motor areas in ET patients with head tremor might suggest cortical plasticity changes due to continuous involuntary head movements. Electronic supplementary material The online version of this article (doi:10.1007/s12311-015-0734-0) contains supplementary material, which is available to authorized users.

Background Psychogenic movement disorders are disorders of movements that cannot be explained by a known neurological disorder and are assumed to be associated with psychiatric symptoms such as depression and anxiety.Objective To examine the neuropsychological profile of patients with psychogenic movement disorders.Methods We examined cognitive functioning using neuropsychological tests in 26 patients with clinically established psychogenic jerky movement disorders (PM D). We included 16 patients with Gilles de la Touren syndrome (GTS) who served as a patient control group, in addition to 22 healthy control subjects. Non-credible test performance was detected using a Symptom Validity Test (SVT). Psychopathology was also assessed.Results Apart from a worse performance on a verbal memory task, no evidence of neuropsychological impairments was found in our PM D sample. Interestingly however, patients with PMD reported more cognitive complaints in daily life and performed worse on the SVT than the two other groups. Patients with GTS did not report, or show, cognitive impairments. In patients with PMD, we found associations between verbal learning, SVT performance and severity of depression and anxiety complaints.Conclusions We conclude that some patients with PMD show non-credible cognitive symptoms. In contrast, no evident cognitive impairments were present in patients with PM D or GTS. Our study underlines the importance of assessment of non-credible response in patients with PM D. Additionally, non-credible response might aid in the differentiation of PM D from other movement disorders.

Objectives: Essential tremor (ET), the most prevalent hyperkinetic movement disorder, is characterized by an action tremor (4-7 Hz). The role of the sensorimotor cortex in tremor generation is uncertain. Previous corticomuscular coupling studies in ET showed either a cortical drive, an afferent input, or both. In contrast, familial cortical myoclonic tremor with epilepsy (FCMTE) with tremulous movements, clinically resembling ET, is characterized by a cortical drive around 15-20Hz. Methods: Corticomuscular directionality was investigated with renormalized partial directed coherence (rPDC) in ET (n=16), FCMTE (n=7), and healthy controls (HC; n=16). EEG-EMG was recorded during 2 minutes of postural tremor (ET and FCMTE right arm outstretched; HC mimicking tremor ±5Hz), and 1 minute of self-paced slow movements

In dystonia, both sensory malfunctioning and an abnormal intermuscular low-frequency drive of 3-7 Hz have been found, although cause and effect are unknown. It is hypothesized that sensory processing is primarily disturbed and induces this drive. Accordingly, experimenter-controlled sensory input should be able to influence the frequency of the drive. In six genetically confirmed myoclonus-dystonia (MD) patients and six matched controls, the low-frequency drive was studied with intermuscular coherence analysis. External perturbations were applied mechanically to the wrist joint in small frequency bands (0-4, 4-8 and 8-12 Hz; 'angle protocol) and at single frequencies (1, 5, 7 and 9 Hz; 'torque' protocol). The low-frequency drive was found in the neck muscles of 4 MD patients. In these patients, its frequency did not shift due to the perturbation. In the torque protocol, the externally applied frequencies could be detected in all controls and in the two patients without the common drive. The common low-frequency drive was not be affected by external perturbations in MD patients. Furthermore, the torque protocol did not induce intermuscular coherences at the applied frequencies in these patients, as was the case in healthy controls and in patients without the drive. This suggests that the dystonic 3-7 Hz drive is caused by a sensory-independent motor drive and sensory malfunctioning in MD might rather be a consequence than a cause of dystonia.

In the present study, eye movements are recorded in two patient groups with an autosomal dominantly inherited cerebellar disorder, i.e. spinocerebellar ataxia type 6 (SCA6) and familial cortical myoclonic tremor with epilepsy (FCMTE). In SCA6 and FCMTE patients striking similarities with the extensive Purkinje cell changes in the cerebellar cortex were described, but the two disorders have a distinctive clinical picture. SCA6 is a late-onset cerebellar syndrome, with relatively minimal brain stem and cerebral cortex symptoms. In contrast, FCMTE is clinically characterized by cortical symptomatology with a distal cortical myoclonic tremor and infrequent epileptic attacks without cerebellar dysarthria and limb ataxia. Comparison of oculomotor function of six FCMTE patients, five SCA6 patients and 18 healthy controls demonstrated both in SCA6 patients and FCMTE patients square wave jerks, downbeat nystagmus (DBN) and a stronger reduced downward smooth pursuit gain than an upward smooth pursuit gain. Only in SCA6 patients horizontal smooth pursuit gain was reduced. Except for the downward direction mean saccadic gain in both patient groups was reduced. This is consistent with cerebellar cortical pathology in both disorders. Subsequently, both patient groups showed increase of DBN with hyperventilation. As a novel finding, only the FCMTE patients showed a significantly increased amount of express saccades in the pro-saccade paradigm.

Background: Tremor is the most prevalent movement disorder in clinical practice. It is defined as involuntary, rhythmic, oscillatory movements. The diagnostic process of patients with tremor can be laborious and challenging, and a clear, systematic overview of available diagnostic techniques is lacking. Tremor can be a symptom of many diseases, but can also represent a distinct disease entity. Objective: The objective of this review is to give a clear, systematic and step-wise overview of the diagnostic work-up of a patient with tremor. The clinical relevance and value of available laboratory tests in patients with tremor will be explored. Methods: We systematically searched through EMBASE. The retrieved articles were supplemented by articles containing relevant data or provided important background information. Studies that were included investigated the value and/or usability of diagnostic tests for tremor. Results: In most patients, history and clinical examination by an experienced movement disorders neurologist are sufficient to establish a correct diagnosis, and further ancillary examinations will not be needed. Ancillary investigation should always be guided by tremor type(s) present and other associated signs and symptoms. The main ancillary examination techniques currently are electromyography and SPECT imaging. Unfortunately, many techniques have not been studied in large prospective, diagnostic studies to be able to determine important variables like sensitivity and specificity. Conclusion: When encountering a patient with tremor, history, and careful clinical examination should guide the diagnostic process. Adherence to the diagnostic work-up provided in this review will help the diagnostic process of these patients.

Objective: Current template-based artifact reduction methods are inadequate to reduce irregular volume- and slice-artifacts induced by limb motion in combined (surface) EMG-fMRI (electromyography-functional magnetic resonance imaging) studies. In addition, artifacts are not removed adequately for EMG frequencies above 50 Hz. We present a new fMRI artifact reduction algorithm for motion (FARM) and compare it with standard artifact correction as implemented in fMRI artifact slice-template removal (FASTR).Methods: One control subject generated motion artifacts during EMG-fMRI. Low-frequency motion artifacts and volume-artifacts were removed prior to slice-artifact correction. Slice-artifacts were phase-shifted and removed with motion adaptive templates (FARM). EMG data were also corrected applying FASTR.Results: Time traces demonstrate that artifacts related to sudden changes in wire position are contained to shorter time periods. EMG power spectra from neck and arm muscles show that FARM has improved performance at higher frequencies.Conclusions: High-pass filtering, volume-artifact removal, phase-shifting and adaptation of slice-templates to motion improve the quality of artifact-corrected EMG recorded during limb motion.Significance: The improved accuracy at which EMG-fMRI data can be obtained opens up new ways to directly relate self-paced movements to brain activations and to study patients suffering from movement disorders. (C) 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.