Search

• This review is the second in the series of articles on the use of clinical neurophysiology for the study of movement disorders. • It focuses on the most useful non-invasive methods and techniques that can probe the neurophysiology of the central nervous system in humans. • Tools include reflex studies, transcranial brain stimulation, electroencephalography and reaction times. This is the second chapter of the series on the use of clinical neurophysiology for the study of movement disorders. It focusses on methods that can be used to probe neural circuits in brain and spinal cord. These include use of spinal and supraspinal reflexes to probe the integrity of transmission in specific pathways; transcranial methods of brain stimulation such as transcranial magnetic stimulation and transcranial direct current stimulation, which activate or modulate (respectively) the activity of populations of central neurones; EEG methods, both in conjunction with brain stimulation or with behavioural measures that record the activity of populations of central neurones; and pure behavioural measures that allow us to build conceptual models of motor control. The methods are discussed mainly in relation to work on healthy individuals. Later chapters will focus specifically on changes caused by pathology. [ABSTRACT FROM AUTHOR]

Objective This study explored the relationships between resting-state electroencephalogram (RS-EEG) localized activation and two important types of executive functions (EF) to extend the prognostic utilization of RS-EEG in children with Attention-Deficit/Hyperactivity Disorder (AD/HD). Also, the role of central nervous system (CNS) arousal in the relationships was examined. Methods Fifty-eight children with AD/HD participated in the study. RS-EEG localized activation was derived from spectral power differences between EEG in eyes-closed and eyes-open conditions. CNS arousal was measured based on alpha band power. Common and everyday EF scores were obtained as EF outcomes. Results Frontal delta activation predicted common EF ability and posterior alpha activation predicted everyday EF. A serial mediation analysis found that lower CNS baseline arousal was related to greater arousal and delta activation in series, which in turn related to worse common EF. A follow-up study found that baseline arousal was related to larger interference cost. Conclusions RS-EEG is indicative of individual differences in two important types of EF in children with AD/HD. Lower CNS arousal may be a driving force for the poorer common EF performance. Significance The current study supports prognostic utilization of RS-EEG and AD/HD models that take resting brain activity into consideration in children with AD/HD. [ABSTRACT FROM AUTHOR]

Objective To evaluate the effects of transcranial direct current stimulation (tDCS) on esophageal peristalsis in patients with gastroesophageal reflux disease (GERD). Methods Patients with GERD preliminary diagnosis were included in a randomized double-blind sham-controlled study. Esophageal manometry was performed before and during transcranial direct current stimulation (tDCS) of the right precentral cortex. Half of patients were randomly assigned to anodal, half to sham stimulation. Distal waves amplitude and pathological waves percentage were measured, after swallowing water boli, for ten subsequent times. Last, a 24 h pH-bilimetry was done to diagnose non-erosive reflux disease (NERD) or functional heartburn (FH). The values obtained before and during anodal or sham tDCS were compared. Results Sixty-eight patients were enrolled in the study. Distal waves mean amplitude increased significantly only during anodal tDCS in NERD ( p = 0.00002) and FH subgroups ( p = 0.008) while percentage of pathological waves strongly decreased only in NERDs ( p = 0.002). Conclusions Transcranial stimulation can influence cortical control of esophageal motility and improve pathological motor pattern in NERD and FH but not in erosive reflux disease (ERD) patients. Significance Pathophysiological processes in GERD are not only due to peripheral damage but to central neural control involvement as well. In ERD patients dysfunctions of the cortico-esophageal circuit seem to be more severe and may affect central nervous system physiology. [ABSTRACT FROM AUTHOR]

Introduction Magnetic stimulation (MS) of the peripheral and central nervous system has driven an increasing clinical interest since the 1980’s. Modelling studies of the electric field (E-field) distributions and neuron mathematical models contributed to understand the physical effects underlying MS mechanisms. These results can improve coil design and optimize clinical protocols ( Salvador et al., 2011 ). Objectives The main objective of this study is to calculate the E-field distribution in the lumbar spinal cord (SC) during spinal MS, for clinical applications. Methods A realistic MRI-based human model was built using the MIMICS software (v16, http://www.materialise.com/mimics ). Calculations of the primary E-field were performed with MATLAB (version 2015b, www.mathworks.com ) and the secondary E-field with COMSOL Multiphysics (version 4.3b, www.comsol.com ). The figure-8 coil was based on Magstim’s double 70 mm model and its vertex was located over the T12 spinous process. Two orientations were considered for the coil: PA, postero-anterior; LR, left–right. In the calculation, the time derivative of the current in the coil was set to 61.6 A/(micro s). Results and show the E-field’s magnitude distribution in the spinal white matter (WM) and grey matter (GM) for PA and LR configurations. For the PA configuration, maximum values of 26.0 and 21.9 V/m are reached in the lumbo-sacral WM and GM, respectively. The E-field is oriented along the caudal-rostral direction. For the LR model, the lower lumbar and sacral SC show the highest values, reaching 15.2 and 11.8 V/m in the WM and GM, respectively. The E-field is oriented along the medial–lateral direction in this region. Conclusion MS of the SC has an E-field magnitude <100 V/m, not sufficient for stimulating excitable nervous tissue. A different geometry and settings of the magnetic coil may be required for lumbar SC excitation. The two configurations present different E-field directions, which could be useful for specific clinical purposes. [ABSTRACT FROM AUTHOR]

Transcutaneous Direct Current Stimulation (tDCS) is a safe technique for modulating central nervous system excitability. We assessed clinical changes in early Huntington’s Disease (HD) following tDCS by evaluating Unified Huntington Disease Rating Scale (UHDRS). tDCS electrodes were applied over the thoracic spinal cord (T9–T11) and parietal cortex of right hemisphere, respectively as anode and cathode. We applied current at a density of 0.071 mA/cm 2 and delivered a total charge density of 85.7 mC/cm 2 . The stimulation consisted in a daily session of treatment during 5 days, of 20 min (2.0 mA) each one. The clinical evaluation was performed before tDCS (T0), after 5 days of treatment (T1) and after 2 weeks from the last session (T2). After tDCS a significant improvement both in motor (T0 vs. T1: 17 vs. 12) and behavioral scores was found (T0 vs. T1 vs. T2: 25 vs. 18 vs. 13). We showed significant effects of tDCS on motor and behavioral symptoms in early HD. The configuration we used likely reduces the abnormal peripheral afferent input, possibly restoring at the same time the balance of interhemispheric communication by interfering with right parietal hyperactivity. [ABSTRACT FROM AUTHOR]

Introduction DKI by measuring non-Gaussian diffusion may better characterize the microstructural brain changes as compared to traditional DTI. The aim was to evaluate the capability of DKI for detecting the microstructural changes induced by alpha-synuclein accumulation in TNWT-61 mice using the tract based spatial statistics (TBSS) and region of interest (ROI) analyses. Methods Fourteen month old TNWT-61 mice and wild-type (WT) littermates underwent DKI scanning using 9.4 Tesla MRI system in vivo . TBSS and ROI analysis was performed to detect the changes in white and gray matter in TNWT-61 and WT mice. Immunohistochemistry for alpha-synuclein was performed in 5 TNWT-61 mice and correlated with DKI findings. Results The principle findings of this study were increase in mean kurtosis and decrease in mean diffusivity in thalamus, sensorimotor cortex, hippocampus, external capsule and basolateral amygdaloid nucleus in 14 month TNWT-61 mice as compared to WT littermates. We also found significant correlations between alpha-synuclein accumulation and increase in kurtosis and decrease in diffusivity in the thalamus. Conclusion Our results reveal that DKI is sensitive in detecting microstructural changes due to alpha-synuclein accumulation in both GM and WM. These findings suggest that in PD patients DKI should be preferred to routine DTI despite a longer acquisition protocol. [ABSTRACT FROM AUTHOR]

Multiple sclerosis (MS) is a chronic inflammatory demyelinating and neurodegenerative disease of the central nervous system. MS can cause different patterns of motor disturbances and gait difficulties in all its main clinical phenotypes: relapsing–remitting (RRMS), secondary-progressive (SPMS) or primary-progressive MS (PPMS). We mesasured gait pattern and characteristics in 54 MS patients, 40 with RRMS and 14 with PPMS. In those two forms we compared effects of dual task paradigm on gait characteristics (motor or mental task performance during gait) and compared gait pattern parameters (gait cycle time, stride length, single and double limb support time, as well as their coefficients of variation). Gait cycle is generally considered as automatically generated rhythmic pattern. However, tasks performed during gait in MS are affecting gait parameters differently. Cycle time is longer and stride length is shorter in RR compared to PP form, while motor and mental tasks are affecting gait parameters of both MS forms in similar manner, increasing their coefficients of variation. Changes in gait parameters and characteristics in RRMS and PPMS forms might be the consequences of different internal and external interactions. Those differences could help to design and separate treatment strategies for different MS forms. [ABSTRACT FROM AUTHOR]

In this clinical observational study 157 patients with MS, without disease modifying therapy, and 56 healthy participants were included. The ulstasonographic examination of the neck blood vessels and deep brain veins was performed. Insufficient drainage was defined by presence of: chronic cerebrospinal vein insuficiency; and/or segmental stenosis of internal jugular vein; and/or reflux in internal jugular vein during Valsalva maneuvre. In the patient group we determined: course of the disease, functional disability determined by EDSS (Expanded Disability Status Scale), disease progression determined by MSSS (Multiple Sclerosis Severity Score). Frequency of at least one of the phenotypes was significantly higher in patients with secundary progressive compared to patients with relapsing–remitting course. Mean values of EDSS and MSSS were significantly higher in patients with at least one of investigated phenotypes compared to patients without the presence of these phenotypes. Insufficient venous drainage of central nervous system (CNS) was significantly more frequent in patients with longer duration of disease, higher grade of functional disability and secondary progressive form of MS. [ABSTRACT FROM AUTHOR]

Inflammatory demyelinating diseases are common in the field of neurology and lead to a destruction of the myelin sheath. Either Oligodendrocytes of the central nervous system (e.g. encephalomyelitis disseminata) or Schwann cells- of the peripheral nervous system (e.g. chronic inflammatory demyelinating polyneuropathy) are affected, but never are both of them at the same time. Within this article we report one of the first documentated two cases of simultaneous demyelination of the central and the peripheral nervous system (Mao and Hu, 2014). First, a 33-year-old male after allogenic stem cell transplantation due to a hodgkins-lymphoma. Our second case is a healthy 28-year-old female patient. Both developed at first a demyelination of the peripheral nervous system and secondly, after four and eight weeks a subacute demyelination of the central nervous system. Both cases showed electrophysiological findings of demyelination, gadolinum -enhanced lesions in MRI and positive oligoclonal bands with high IgG-indices in the cerebrospinal fluid. Up to our knowledge these are the first two cases of a central and a peripheral demyelination. As a consequence of the affection of both: peripheral and central myelin sheath we postulate that there has to be a similar antigen between these two different cell-identities: oligodendrocytes and Schwann cells . Further we address the question of a not yet known pathomechanism, affecting both nervous systems simultaneously and leading to the postulation of a finding of a new demyelinisating disease identity, affecting the two different- and dissimiliar- nervous-systems. [ABSTRACT FROM AUTHOR]

Background Diffusion tensor imaging (DTI) has successfully been used to investigate ALS-related changes in the central nervous system (CNS). Many studies reported, for example, decreased white matter integrity in the cortico-spinal tract (CST). Consequently, DTI has been proposed as a potential biomarker to support clinical diagnosis. While recent results look promising in principle, the reliability of DTI-based diagnosis seems currently insufficient for practical use. To enhance discriminative performance, one would ideally integrate information from complementary diagnostic modalities during classifier construction. Objective In a recent study, we observed ALS-related thinning of different peripheral nerves based on cross-sectional area (CSA) measurements using high-resolution ultrasound ( Schreiber et al., 2014 ). Here, we combined DTI-based measures of the CST with CSA of the upper limb peripheral nerves to improve imaging-based discrimination between different ALS subtypes and healthy controls. Methods 51 patients with ALS (14 classic, 10 upper motor neuron dominant (UMND), 14 lower motor neuron dominant (LMND), 8 bulbar, and 5 primary lateral sclerosis (PLS)) and 18 healthy controls underwent diffusion-weighted MRI at 3T and peripheral nerve ultrasound in order to determine the fractional anisotropy (FA) in the white matter underneath the motor cortex, posterior limb of the internal capsule, cerebral peduncle, pons and medulla oblongata as well as the CSA of the N. medianus and the N. ulnaris. Statistical comparisons were conducted using analysis of variance (ANOVA). Classifier construction was carried using linear discriminants after dimensionality reduction based on principal component analysis. Separate classifiers were constructed using FA, CSA, and both FA and CSA data, respectively. Results Compared to controls, ALS patients exhibited significant, distally pronounced reductions of the ulnar nerve CSA across all subtypes with the exception of PLS. In addition, DTI data revealed significant differences between ALS subtypes with pronounced impairment of the CST in UMND and PLS and modest impairment in LMND patients, while bulbar ALS is intermediately located within this spectrum. Classification performance was considerably higher exploiting both central and peripheral data compared to using either modality alone. Most notably, UMND and PLS patients could be accurately separated. Conclusion Combining central and peripheral data acquired through DTI and ultrasound, respectively, leads to improved discrimination not only between ALS and healthy controls, but also between ALS subtypes. This speaks to the complementary role of both methods regarding their contribution to classification performance. The potential of combining both imaging methods is particularly evident in the reliable separation of UMND and PLS patients, since early differentiation of these subtypes remains a difficult problem in clinical practice. [ABSTRACT FROM AUTHOR]