Voluntary Relaxation Research Articles

Validating the measurement of passive Musculo-articular wrist stiffness without intentional or reactive contraction using axillary plexus block

BackgroundPassive stiffness describes how easily a joint may move passively. To accurately measure wrist stiffness, an electro-oscillation device was developed. The objectives were to 1) ensuring that the measurement are free from intentional or reflex contraction, 2) analyzing how forearm anatomy affects the passive stiffness of the wrist and 3) determining the clinical practical relevance of the device. MethodsIn this prospective study, the device generated low amplitude sinusoidal motions in flexion and extension on the wrist to quantify elastic and viscous passive stiffness in voluntary orthopaedic patients. The first series of measurements was carried out in the state of voluntary relaxation, the second series of measurements was carried out after an axillary plexus anesthetic block. A matched group of healthy subjects were use for control. FindingsThe Electromechanical Oscillation methods effectively enable the measurement of passive joint stiffness since the stiffness values obtained show no statistically significant difference pre-post the anesthesia. The stiffness values are comparable to those of healthy subjects. The effect of forearm passive structure, estimated by the perimeter of the forearm, influences the passive stiffness of the wrist, mainly the viscous component. InterpretationThe use of sinusoidal oscillation was well accepted by the participants, demonstrating its usefulness and applicability in a clinical setting. This work serves as a foundation for future investigations of orthopaedic and/or neurological pathological conditions characterized by abnormal passive joint stiffness of the wrist. It paves the way for its use as a diagnostic, prognostic, and monitoring tool in these pathologies.

EFFECTIVENESS OF PERINEAL PELVIS REHABILITATION COMBINED WITH BIOFEEDBACK AND RADIOFREQUENCY DIATHERMY (RDF) IN ANORECTAL FUNCTIONAL PAIN SYNDROMES ASSOCIATED WITH PARADOXICAL CONTRACTION OF THE LEVATOR ANI MUSCLES. A PROSPECTIVE STUDY.

•Anorectal functional pain syndrome is a very often disabling disease with a consequent significant negative impact on the patient's quality of life. Chronic proctalgia, in many patients, is secondary to the paradoxical contraction of the pelvic floor and associated with a dissynergy between the thorax-abdomen and the pelvic floor. •The use of radiofrequency diathermy with a system of static electrodes associated with biofeedback represents a valid rehabilitation option for those patients suffering from anorectal functional pain syndrome because it reduces pain and paradoxical contraction of the levator ani and improves quality of life of the patient. Background - Anorectal functional pain syndrome, also called chronic proctalgia, represents a neglected clinical entity and often confused with other syndromes such as vulvodynia or acute proctalgia. It is a very often disabling disease with a consequent significant negative impact on the patient's quality of life. Chronic proctalgia, in many patients, is secondary to the paradoxical contraction of the pelvic floor and associated with a dissynergy between the thorax-abdomen and the pelvic floor. To improve symptoms in functional anorectal pain syndromes, various rehabilitation techniques are used with the aim of promoting relaxation of the pelvic floor; however, to improve defecatory dynamics in patients with levator ani syndrome, only biofeedback has shown efficacy in a randomized study. The aim of this work is to evaluate whether a rehabilitation protocol with manometric biofeedback and radiofrequency diathermy (mt100 Fremslife emotion Tecar) reduces pain and paradoxical contraction of the levator ani and improves the quality of life in patients with anorectal pain syndromes. functional. Methods - This was a prospective study on 30 patients (20 women and 10 men) with anorectal functional pain syndrome and paradoxical contraction of the pelvic floor enrolled at the UOC of General, Minimally Invasive, Oncological and Obesity Surgery of the AOU "Luigi Vanvitelli" of Naples, Italy, from September 2021 to May 2022. All patients were evaluated with a coloproctological specialist visit followed by anorectal manometry and evaluation of altered clinical physiatric parameters (Brusciano Score). The protocol consisted of 10 rehabilitation sessions of the pelvic floor once a week and lasting approximately 45 minutes. During the sessions the patients were subjected to diathermy / radiofrequency treatment (10 minutes) with a static resistive electrode on the diaphragm, during which they were required to breathe diaphragmatically and to become aware of the perineal muscles, under the supervision of a physiotherapist; followed by application of diathermy with static capacitive (5 minutes) and resistive (10 minutes) electrode at the lumbar level. This was followed by the use of manometric biofeedback (15 minutes of tonic / phasic exercises) in order to instruct the patient on the reflex mechanism to obtain a voluntary relaxation of the external anal sphincter. The variables evaluated were Pain (VAS 0-10) and the questionnaire on the impact of colorectal and anal pathologies on the quality of life (CRAIQ-7) at the beginning, after 3 months and at the end of the treatment. Results - After 10 weeks, the rehabilitation treatment combined with diathermy and manometric biofeedback proved effective in the short term with a reduction in the scores of the Vas scale and CRAIQ-7 questionnaire and an increase in the percentage of release of the anal muscles on anorectal manometry. Conclusion - The use of radiofrequency diathermy with a system of static electrodes associated with biofeedback represents a valid rehabilitation option for those patients suffering from anorectal functional pain syndrome because it reduces pain and paradoxical contraction of the levator ani and improves quality of life of the patient.

Exercise Position to Improve Synergy Between the Diaphragm and Pelvic Floor Muscles in Women With Pelvic Floor Dysfunction: A Cross Sectional Study

ObjectiveThis study aimed to investigate the synergy between the diaphragm and pelvic floor muscles (PFM) according to different exercise positions in women with pelvic floor dysfunction. Our secondary aim was to determine the short-term effects of single-week pelvic floor muscle training (PFMT) program on diaphragmatic function. MethodsThe cross-sectional study included 64 women with pelvic floor dysfunction. The participants' diaphragm and abdominal muscle functions during voluntary PFM contraction and relaxation were assessed by surface electromyography and ultrasonography. The surface electromyography assessments were performed in supine (P1), crawling (P2) and sitting (P3) positions. A single week-PFMT was conducted on women who agreed to determine the short-term responses of the diaphragm function. The muscle functions according to exercise positions were compared with Friedman Analysis of Variance, and the short-term effects of single-week PFMT on diaphragm function was analyzed with Wilcoxon Signed-Ranks Test. ResultsThe diaphragm activity during voluntary PFM contraction was highest in P2 before and after single-week PFMT (P < .001). Positive significant correlations were found between the activities diaphragm and abdominal muscles in different exercise positions (P < .05). After single-week PFMT, diaphragm thickness increased (P = .030) in P1, but diaphragm activity did not change in all 3 exercise positions (P > .05). ConclusionThe synergy between the diaphragm and PFM was greater in the crawling position in women with pelvic floor dysfunction. The abdominal muscles seemed to contribute to maintaining this synergy. Therefore, PFMT combined with diaphragmatic breathing exercises in the crawling position should be considered. In addition, single-week PFMT may positively affect diaphragm function in the short-term.

Comparison of spasticity measurements with surface electromyography in the affected and unaffected side of children with hemiparetic cerebral palsy

Aims: Various methods are used in the evaluation of spasticity, which is common in Cerebral Palsy (CP). However, studies measuring upper extremity spasticity with Surface Electromyography (sEMG) were found to be insufficient in children with CP. In this study, the comparison of Modified Ashworth Scale (MAS) and sEMG measurements for bilateral upper extremity spasticity in children with Hemiparetic CP was aimed. Methods: 33 (11.03 ± 3.82 years, 11F-2M) patients with hemiparetic CP and 32 healthy controls (10.31± 2.88 years, 16F-16M) with a similar mean age were included in the study. Results: Upper extremity spasticities of both sides of the cases were evaluated with MAS and SEMG. Affected side MAS results were found to be higher than the unaffected side (p&lt;0.05). The mean sEMG value of the wrist flexors was lower on the affected side during voluntary contraction and higher during voluntary relaxation (p&lt;0.05). In addition, the maximum percentage of voluntary contraction was measured higher on the affected side (p&lt;0.05). Conclusion: Spasticity, as assessed by sEMG and MAS, was increased on the affected side. MAS and sEMG give consistent results. These results show us that the YEMG method can be used for spasticity measurements. It is considered that MAS would be a preferable method in evaluating spasticity owing to the fact that it is easy to use and it does not constitute extra costs.

MP52-20 OPTIMISATION OF TRANSCUTANEOUS SPINAL CORD STIMULATION IN MODULATION OF MICTURITION REFLEXES FOLLOWING SPINAL CORD INJURY

You have accessJournal of UrologyCME1 Apr 2023MP52-20 OPTIMISATION OF TRANSCUTANEOUS SPINAL CORD STIMULATION IN MODULATION OF MICTURITION REFLEXES FOLLOWING SPINAL CORD INJURY Hannah Houliston, Richard Nobrega, Natalia Vasquez, Frank Lee, and Sarah Knight Hannah HoulistonHannah Houliston More articles by this author , Richard NobregaRichard Nobrega More articles by this author , Natalia VasquezNatalia Vasquez More articles by this author , Frank LeeFrank Lee More articles by this author , and Sarah KnightSarah Knight More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003300.20AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Spinal cord injury (SCI) can result in neurogenic lower urinary tract dysfunction including neurogenic detrusor over-activity (NDO) and detrusor-sphincter dyssynergia (DSD). Exciting developments in spinal cord stimulation (SCS) have demonstrated potential to improve motor function. Transcutaneous SCS (tSCS) provides a non-invasive alternative to epidural SCS, and there is preliminary evidence to suggest it can modulate spinal networks involved in micturition. However, there is ambiguity regarding optimal electrode sites and stimulation parameters. The aim of this study was to investigate optimisation of electrode site and tSCS parameters during the filling and voiding phase of the micturition cycle in people with SCI. METHODS: Ethical approval was obtained from the Research Ethics Committee. Participants were recruited if they had a supra-sacral SCI and proven NDO on most recent urodynamics. During visit 1, 1 ms tSCS pulses of increasing amplitude where administered at three randomised electrode sites; cathode between spinous process of T11-12, or L1-2, anodes at iliac crests or abdomen. External anal sphincter (EAS) and bilateral tibialis anterior EMG were recorded throughout. Optimal electrode site was selected based on motor-evoked potential response, and tolerance to stimulation. With electrodes placed at the optimal site, tSCS was applied in 5 s bursts at either 1, 15 or 30 Hz during voluntary pelvic floor contraction, relaxation and control. During visit 2, participants completed 6 cycles of urodynamics, one control cycle at the start and end, two cycles applying either 30 or 15 Hz tSCS during bladder filling, and two cycles applying either 1 or 15 Hz tSCS during voiding. RESULTS: Six participants were recruited (4 male, 2 female), with mean age 50±20 years old. 4 had an incomplete cervical and 2 an incomplete thoracic SCI. All participants tolerated the stimulation, and there were no adverse events. Optimal electrode sites were cathode L1-2, anode abdomen (n=2), cathode T11-12, anode iliac crest (n=2), cathode L1-2, anode iliac crest (n=1) and cathode T11-12, anode abdomen (n=1). Preliminary analysis of EMG data indicates that tSCS may enhance voluntary contraction of EAS. In addition, tSCS during the filling phase may increase bladder capacity. Further analysis is on-going. CONCLUSIONS: tSCS is an exciting new development which may improve bladder and bowel function following SCI. Our initial studies optimising electrode positioning and parameters will be used to investigate the use of tSCS in a further study combining it with pelvic floor muscle training. Source of Funding: International Spinal Research Trust Grant © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e710 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Hannah Houliston More articles by this author Richard Nobrega More articles by this author Natalia Vasquez More articles by this author Frank Lee More articles by this author Sarah Knight More articles by this author Expand All Advertisement PDF downloadLoading ...

Clinical assessment of pelvic floor and abdominal muscles 3 months post partum: an inter-rater reliability study

ObjectivesEvaluation of the inter-rater reliability of clinical assessment methods for pelvic floor muscles and diastasis recti abdominis post partum.DesignA multicentre inter-rater reliability study.SettingThree primary care rehabilitation centres in Sweden.ParticipantsA total...

Time and Frequency Patterns Identification of sEMG Signals Using Hilbert-Huang Transform

This article reports the identification of two groups of patterns in time and frequency, also a muscular intensity characteristic associated to hand movement per user, all this results were obtained by superficial myoelectric signal analysis using Hilbert-Huang transform. Muscular signals were acquired from five muscles of the right forearm from five healthy subjects. Using a four channels acquisition system with differential configuration myoelectric signals were recorded for six movements of the fingers in flexion and extension. Electrodes were placed over five forearm anterior, posterior and finger linked muscles. Time pattern corresponds to sinusoidal oscillations with average length of 24.5 ms, corresponding to voluntary contraction and relaxation of the muscles. These oscillations are present into all acquisition channels and there is evidence about groups of two consecutive oscillations with a range of 30 ms between them. Also, there found a pattern of three frequencies: 83.3 Hz, 96.7 Hz and 113.3 Hz, present into contraction and relaxation timeslot. Using Hilbert transform were identified the instantaneous frequencies that indicate the state of the muscles from doss to active and vice versa. There is an intensity characteristic identified in the recordings about behavior of muscles per movement for each subject being repetitive and unique. These processes could decrease time computing to obtain intrinsic characteristics for myoelectric signals.

Effects of intensity on muscle-specific voluntary electromechanical delay and relaxation electromechanical delay

ABSTRACTThe purposes of this study were to examine: 1) the potential muscle-specific differences in voluntary electromechanical delay (EMD) and relaxation electromechanical delay (R-EMD), and 2) the effects of intensity on EMD and R-EMD during step incremental isometric muscle actions from 10 to 100% maximal voluntary isometric contraction (MVIC). EMD and R-EMD measures were calculated from the simultaneous assessments of electromyography, mechanomyography, and force production from the vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF) during step isometric muscle actions. There were no differences between the VL, VM, and RF for the voluntary EMDE-M (onsets of the electromyographic to mechanomyographic signals), EMDM-F (onsets the mechanomyographic to force production), or EMDE-F (onsets of the electromyographic signal to force production) as well as R-EMDE-M (cessation of electromyographic to mechanomyographic signal), R-EMDM-F (cessation of mechanomyographic signal to force cessation), or R-EMDE-F (cessation of electromyorgraphic signal to force cessation) at any intensity. There were decreases in all EMD and R-EMD measures with increases in intensity. The relative contributions from EMDE-M and EMDM-F to EMDE-F as well as R-EMDE-M and R-EMDM-F to R-EMDE-F remained similar across all intensities. The superficial muscles of the quadriceps femoris shared similar EMD and R-EMD measurements.

Effects of Fatigue on Voluntary Electromechanical and Relaxation Electromechanical Delay.

The purposes of the present study were to examine: 1) the effects of fatigue on electromechanical delay from the onsets of the electromyographic signal to force production (EMDE-F), the onsets of the electromyographic to mechanomyographic signals (EMDE-M), the onsets of the mechanomyographic signal to force production (EMDM-F), as well as the cessations of the electromyographic to force production (R-EMDE-F), cessation of the electromyographic to mechanomyographic signals (R-EMDE-M), and cessations of the mechanomyographic signal to force production (R-EMDM-F); and 2) the relative contributions from EMDE-M and EMDM-F to EMDE-F as well as R-EMDE-M and R-EMDM-F to R-EMDE-F from the vastus lateralis in non-fatigued and fatigued states. The values EMDE-F, EMDE-M, EMDM-F, R-EMDE-F, R-EMDE-M and R-EMDM-F were calculated during maximal voluntary isometric contractions, before and after 70% 1-repetition maximum leg extensions to failure. There were significant pretest to posttest increases in EMDE-F (73%;p<0.01), EMDE-M (99%;p<0.01), EMDM-F (60%;p<0.01), R-EMDE-F (101%;p<0.01) and R-EMDM-F (368%;p<0.01), but no significant change in R-EMDE-M (25%;p=0.46). Fatigue-induced increase in EMDE-F indicated excitation-contraction coupling failure (EMDE-M) and increases in the compliance of the series elastic component (EMDM-F). Increases in R-EMDE-F were due to increases in relaxation time for the series elastic component (R-EMDM-F), but not changes in the reversal of excitation-contraction coupling (R-EMDE-M).

Effects of galvanic skin response feedback on user experience in gaze-controlled gaming: A pilot study.

Eye-tracking (ET) is one of the most intuitive solutions for enabling people with severe motor impairments to control devices. Nevertheless, even such an effective assistive solution can detrimentally affect user experience during demanding tasks because of, for instance, the user's mental workload - using gaze-based controls for an extensive period of time can generate fatigue and cause frustration. Thus, it is necessary to design novel solutions for ET contexts able to improve the user experience, with particular attention to its aspects related to workload. In this paper, a pilot study evaluates the effects of a relaxation biofeedback system on the user experience in the context of a gaze-controlled task that is mentally and temporally demanding: ET-based gaming. Different aspects of the subjects' experience were investigated under two conditions of a gaze-controlled game. In the Biofeedback group (BF), the user triggered a command by means of voluntary relaxation, monitored through Galvanic Skin Response (GSR) and represented by visual feedback. In the No Biofeedback group (NBF), the same feedback was timed according to the average frequency of commands in BF. After the experiment, each subject filled out a user experience questionnaire. The results showed a general appreciation for BF, with a significant between-group difference in the perceived session time duration, with the latter being shorter for subjects in BF than for the ones in NBF. This result implies a lower mental workload for BF than for NBF subjects. Other results point toward a potential role of user's engagement in the improvement of user experience in BF. Such an effect highlights the value of relaxation biofeedback for improving the user experience in a demanding gaze-controlled task.

Voluntary regulation of the functional state and its influence on the effectiveness of cognitive activity during adolescence

We have analyzed the impact of voluntary relaxation on the functional organization and the effectiveness of the voluntary prestimulus attention in performing cognitive tasks in adolescents at the ages of 12–13 and 13–14 years. The effectiveness of cognitive task performance (audio-verbal short-term memory) was estimated on the basis of the number of correctly remembered words. We have found that both age groups are characterized by reduced capacity for voluntary relaxation and its impact on the effectiveness of cognitive task performance. The analysis of the coherence function of EEG rhythmic components in a situation of voluntary attention focused on the performance of cognitive tasks showed no significant change in the interaction of the prefrontal cortex with other cortical areas during the switch from quiet wakefulness or post-relaxation state to the preparation to perform the task, which is typical of adults and young children. Our findings can be a result of sub-optimal functioning of voluntary regulation mechanisms and organization of activities during adolescence.

P144 Motor cortical stimulation versus voluntary relaxation to study muscle relaxation properties in different muscle conditions

Question Transcranial magnetic stimulation (TMS) over the motor cortex can induce abrupt muscle relaxation by inhibition of corticospinal drive to the activated muscles. Voluntary relaxation (VR) is more commonly used to study muscle relaxation properties. These two methods have never directly been compared. The aim of our study is to investigate if variability of TMS-induced relaxation is lower compared to VR. To further validate the use of TMS in assessing muscle relaxation we studied the effects of cooling and fatigue to see if we could reproduce the well-known slowing effects of these conditions on muscle relaxation. Methods Twenty-five subjects (14 men, 11 women) participated in this study. Handgrip dynamometry was used to assess relaxation properties of extrinsic finger flexors. Subjects performed repeated maximal voluntary contractions with VR and TMS-induced relaxation in fresh, cooled, and fatigued muscle conditions (Fig. 1). Peak relaxation rate (pRR), pRR normalized to maximal force (NpRR), and relaxation times were calculated. Within- and between-subject variability was assessed by calculating within- and between-subject coefficient of variability (CV), intraclass correlation coefficient (ICC), and repeatability coefficient (RC). Results All outcome measures showed lower variability in TMS-induced relaxation compared to VR. This is demonstrated by lower within- and between-subject CV, ICC, and RC; e.g. for NpRR in men, TMS-induced relaxation has a within-subject CV of 3.3% vs 22.2% in VR, RC of 1.3 vs 6.1 s−1, ICC of 0.95 vs 0.60, and between-subject CV of 15.2% vs 27.4%.The slowing effects of cooling and fatigue could reliably be demonstrated using TMS (Fig. 2). Conclusions Variability of TMS-induced muscle relaxation was lower compared to VR. A clinical implication is that for future studies on muscle relaxation, measurements are more reliable and less subjects would be needed using TMS to demonstrate differences in relaxation properties. Download : Download high-res image (379KB) Download : Download full-size image Download : Download high-res image (214KB) Download : Download full-size image

Modulation of motor cortex inhibition during motor imagery.

Motor imagery (MI) is similar to overt movement, engaging common neural substrates and facilitating the corticomotor pathway; however, it does not result in excitatory descending motor output. Transcranial magnetic stimulation (TMS) can be used to assess inhibitory networks in the primary motor cortex via measures of 1-ms short-interval intracortical inhibition (SICI), long-interval intracortical inhibition (LICI), and late cortical disinhibition (LCD). These measures are thought to reflect extrasynaptic GABAA tonic inhibition, postsynaptic GABAB inhibition, and presynaptic GABAB disinhibition, respectively. The behavior of 1-ms SICI, LICI, and LCD during MI has not yet been explored. This study aimed to investigate how 1-ms SICI, LICI, and LCD are modulated during MI and voluntary relaxation (VR) of a target muscle. Twenty-five healthy young adults participated. TMS was used to assess nonconditioned motor evoked potential (MEP) amplitude, 1-ms SICI, 100- (LICI100) and 150-ms LICI, and LCD in the right abductor pollicis brevis (APB) and right abductor digiti minimi during rest, MI, and VR of the hand. Compared with rest, MEP amplitudes were facilitated in APB during MI. SICI was not affected by task or muscle. LICI100 decreased in both muscles during VR but not MI, whereas LCD was recruited in both muscles during both tasks. This indicates that VR modulates postsynaptic GABAB inhibition, whereas both tasks modulate presynaptic GABAB inhibition in a non-muscle-specific way. This study highlights further neurophysiological parallels between actual and imagined movement, which may extend to voluntary relaxation.NEW & NOTEWORTHY This is the first study to investigate how 1-ms short-interval intracortical inhibition, long-interval intracortical inhibition, and late cortical disinhibition are modulated during motor imagery and voluntary muscle relaxation. We present novel findings of decreased 100-ms long-interval intracortical inhibition during voluntary muscle relaxation and increased late cortical disinhibition during both motor imagery and voluntary muscle relaxation.

Effect of neuromuscular electrical stimulation on motor cortex excitability upon release of tonic muscle contraction

The aim of the present study was to investigate the neurophysiological triggers underlying muscle relaxation from the contracted state, and to examine the mechanisms involved in this process and their subsequent modification by neuromuscular electrical stimulation (NMES). Single-pulse transcranial magnetic stimulation (TMS) was used to produce motor-evoked potentials (MEPs) and short-interval intracortical inhibition (SICI) in 23 healthy participants, wherein motor cortex excitability was examined at the onset of voluntary muscle relaxation following a period of voluntary tonic muscle contraction. In addition, the effects of afferent input on motor cortex excitability, as produced by NMES during muscle contraction, were examined. In particular, two NMES intensities were used for analysis: 1.2 times the sensory threshold and 1.2 times the motor threshold (MT). Participants were directed to execute constant wrist extensions and to release muscle contraction in response to an auditory “GO” signal. MEPs were recorded from the flexor carpi radialis (FCR) and extensor carpi radialis (ECR) muscles, and TMS was applied at three different time intervals (30, 60, and 90 ms) after the “GO” signal. Motor cortex excitability was greater during voluntary ECR and FCR relaxation using high-intensity NMES, and relaxation time was decreased. Each parameter differed significantly between 30 and 60 ms. Moreover, in both muscles, SICI was larger in the presence than in the absence of NMES. Therefore, the present findings suggest that terminating a muscle contraction triggers transient neurophysiological mechanisms that facilitate the NMES-induced modulation of cortical motor excitability in the period prior to muscle relaxation. High-intensity NMES might facilitate motor cortical excitability as a function of increased inhibitory intracortical activity, and therefore serve as a transient trigger for the relaxation of prime mover muscles in a therapeutic context.

Time Course of Corticospinal Excitability and Intracortical Inhibition Just before Muscle Relaxation

Using transcranial magnetic stimulation (TMS), we investigated how short-interval intracortical inhibition (SICI) was involved with transient motor cortex (M1) excitability changes observed just before the transition from muscle contraction to muscle relaxation. Ten healthy participants performed a simultaneous relaxation task of the ipsilateral finger and foot, relaxing from 10% of their maximal voluntary contraction (MVC) force after the go signal. In the simple reaction time (RT) paradigm, single or paired TMS pulses were randomly delivered after the go signal, and motor evoked potentials (MEPs) were recorded from the right first dorsal interosseous (FDI) muscle. We analyzed the time course prior to the estimated relaxation reaction time (RRT), defined here as the onset of voluntary relaxation. SICI decreased in the 80–100 ms before RRT, and MEPs were significantly greater in amplitude in the 60–80 ms period before RRT than in the other intervals in single-pulse trials. TMS pulses did not effectively increase RRT. These results show that cortical excitability in the early stage, before muscle relaxation, plays an important role in muscle relaxation control. SICI circuits may vary between decreased and increased activation to continuously maintain muscle relaxation during or after a relaxation response. With regard to M1 excitability dynamics, we suggest that SICI also dynamically changes throughout the muscle relaxation process.

Anal sphincter dysfunction in multiple sclerosis: an observation manometric study.

Constipation, obstructed defecation, and fecal incontinence are frequent complaints in multiple sclerosis. The literature on the pathophysiological mechanisms underlying these disorders is scant. Using anorectal manometry, we compared the anorectal function in patients with and without multiple sclerosis.136 patients referred from our Center for Multiple Sclerosis to the Coloproctology Outpatient Clinic, between January 2005 and December 2011, were enrolled. The patients were divided into four groups: multiple sclerosis patients with constipation (group A); multiple sclerosis patients with fecal incontinence (group B); non-multiple sclerosis patients with constipation (group C); non-multiple sclerosis patients with fecal incontinence (group D). Anorectal manometry was performed to measure: resting anal pressure; maximum squeeze pressure; rectoanal inhibitory reflex; filling pressure and urge pressure. The difference between resting anal pressure before and after maximum squeeze maneuvers was defined as the change in resting anal pressure calculated for each patient.ResultsGroup A patients were noted to have greater sphincter hypotonia at rest and during contraction compared with those in group C (p=0.02); the rectal sensitivity threshold was lower in group B than in group D patients (p=0.02). No voluntary postcontraction sphincter relaxation was observed in either group A or group B patients (p=0.891 and p=0.939, respectively).ConclusionsThe decrease in the difference in resting anal pressure before and after maximum squeeze maneuvers suggests post-contraction sphincter spasticity, indicating impaired pelvic floor coordination in multiple sclerosis patients. A knowledge of manometric alterations in such patients may be clinically relevant in the selection of patients for appropriate treatments and for planning targeted rehabilitation therapy.

Non-neurogenic Bladder Dysfunction in Children

Non-neurogenic bladder dysfunction, or bladder dysfunction in children with an intact nervous system, falls under the generic term of dysfunctional elimination. This bladder dysfunction encompasses a variety of different symptom presentations whose unifying characteristic usually involves an overactive bladder or involuntary and uninhibited bladder contractions. This syndrome of dysfunctional elimination is linked to pelvic floor dysfunction which does not allow for adequate voluntary pelvic floor relaxation which then prevents complete emptying during micturition or defecation, resulting in extreme cases in urinary and fecal incontinence. The origins and most appropriate therapies for this disorder remain a matter of debate. We will present what we believe the preponderance of the evidence points to as the causes of non-neurogenic bladder dysfunction in children and methods for its most efficacious prevention and treatment.

Excitability changes in primary motor cortex just prior to voluntary muscle relaxation.

We postulated that primary motor cortex (M1) activity does not just decrease immediately prior to voluntary muscle relaxation; rather, it is dynamic and acts as an active cortical process. Thus we investigated the detailed time course of M1 excitability changes during muscle relaxation. Ten healthy participants performed a simple reaction time task. After the go signal, they rapidly terminated isometric abduction of the right index finger from a constant muscle force output of 20% of their maximal voluntary contraction force and performed voluntary muscle relaxation. Transcranial magnetic stimulation pulses were randomly delivered before and after the go signal, and motor evoked potentials (MEPs) were recorded from the right first dorsal interosseous muscle. We selected the time course relative to an appropriate reference point, the onset of voluntary relaxation, to detect excitability changes in M1. MEP amplitude from 80 to 60 ms before the estimated electromyographic offset was significantly greater than that in other intervals. Dynamic excitability changes in M1 just prior to quick voluntary muscle relaxation indicate that cortical control of muscle relaxation is established through active processing and not by simple cessation of activity. The cortical mechanisms underlying muscle relaxation need to be reconsidered in light of such dynamics.

Fisiología del tracto urinario inferior

The lower urinary tract has two functional units: a reservoir (the bladder) and an outlet tract (bladder neck, urethra and external urethral sphincter). It is innervated by the sympathetic, parasympathetic and somatic nervous system (NS). During urine storage the bladder is relaxed and the outlet tract contracted (due to an activated sympathetic NS, an inhibited parasympathetic NS and an activation of the somatic NS with increased external urethral sphincter tone and voluntary control of it). During urine emptying the bladder is contracted and the outlet tract relaxed (due to a voluntary relaxation of the external urethral sphincter and an activation of the parasympathetic NS). This operation is controlled by a complex supraspinal neural network systematized in three circuits constituted by the midbrain periaqueductal gray matter and pontine structures, the limbic system and the cortical and cingulated system, which allow the micturition reflex to be mechanically appropriate, emotionally safe and socially appropriate respectively. The knowledge of normal physiology and of the anatomical location of nervous system pathology allows us to infer most of the secondary voiding dysfunctions.

The control of defecation in humans: an evolutionary advantage?

Defecation is a physiological event present in every individual, consisting of the expulsion of fecal matter, and in normal conditions, mostly occurring in the morning or after meals provided the appropriate neuroanatomical circuits are intact [1, 2]. Due to the fact that it involves a very private sphere and is the object of cultural taboos, the act of defecation is rarely thought of, even by physicians, even though it involves complex anatomical, psychophysiological, and neurological relationships, disruption of which can lead to constipation or incontinence [3, 4]. In brief, actual defecation is the result of synchronized ileo-colo-recto-anal motility, with voluntary sphincteric relaxation allowing the expulsion of fecal matter [1, 2]. Semiliquid intestinal content arriving in the terminal ileum elicits powerful contractions that propels this content into the large bowel; here, a mix of segmental and propulsive activity progressively compacts the content and shifts it toward the rectum, where it is temporarily stored until the subject (alerted by defecation stimuli) decides it is convenient to defecate [1, 2]. The act of defecation, in a healthy individual, is under strict voluntary control; thus, the individual decides if and when (mostly depending on environmental/social events) it is opportune to defecate. We put forward the hypothesis, which is very difficult to prove, that this rigid control of defecation may have evolved not only due to social amenities but as an evolutionary advantage.