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Transcranial static magnetic stimulation (tSMS) is a novel non-invasive brain stimulation technique that reduces cortical excitability at the stimulation site. We investigated the effects of tSMS over the left primary motor cortex (M1) for 20 min on the local electroencephalogram (EEG) power spectrum and interregional EEG coupling. Twelve right-handed healthy subjects participated in this crossover, double-blind, sham-controlled study. Resting-state EEG data were recorded for 3 min before the intervention and 17 min after the beginning of the intervention. The power spectrum at the left central electrode (C3) and the weighted phase lag index (wPLI) between C3 and the other electrodes was calculated for theta (4–8 Hz), alpha (8–12 Hz), and beta (12–30 Hz) frequencies. The tSMS significantly increased theta power at C3 and the functional coupling in the theta band between C3 and the parietal midline electrodes. The tSMS over the left M1 for 20 min exhibited modulatory effects on local cortical activity and interregional functional coupling in the theta band. The neural oscillations in the theta band may have an important role in the neurophysiological effects induced by tSMS over the frontal cortex.

Transcranial static magnetic stimulation (tSMS) has been focused as a new non-invasive brain stimulation, which can suppress the human cortical excitability just below the magnet. However, the non-regional effects of tSMS via brain network have been rarely studied so far. We investigated whether tSMS over the left primary motor cortex (M1) can facilitate the right M1 in healthy subjects, based on the hypothesis that the functional suppression of M1 can cause the paradoxical functional facilitation of the contralateral M1 via the reduction of interhemispheric inhibition (IHI) between the bilateral M1. This study was double-blind crossover trial. We measured the corticospinal excitability in both M1 and IHI from the left to right M1 by recording motor evoked potentials from first dorsal interosseous muscles using single-pulse and paired-pulse transcranial magnetic stimulation before and after the tSMS intervention for 30 min. We found that the corticospinal excitability of the left M1 decreased, while that of the right M1 increased after tSMS. Moreover, the evaluation of IHI revealed the reduced inhibition from the left to the right M1. Our findings provide new insights on the mechanistic understanding of neuromodulatory effects of tSMS in human.

Key points Neuropathic pain spreads spatially beyond the injured sites, and the mechanism underlying the spread has been attributed to inflammation occurring in the spinal cord.However, the spatial spread of spinal/cortical potentiation induced by conduction block of the peripheral nerves can be observed prior to inflammation.In the present study, we found that spreading potentiation and hypersensitivity acutely induced by unilateral hindpaw ischaemia are nitric oxide (NO)‐dependent and that NO is produced by ischaemia and quickly diffuses within the spinal cord.We also found that NO production induced by ischaemia is not observed in the presence of an antagonist for group II metabotropic glutamate receptors (mGluRs) and that neuronal NO synthase‐positive dorsal horn neurons express group II mGluRs.These results suggest strongly that NO‐mediated spreading potentiation in the spinal cord is one of the trigger mechanisms for neuropathic pain. Abstract Cortical/spinal responses to hindpaw stimulation are bilaterally potentiated by unilateral hindpaw ischaemia in mice. We tested the hypothesis that hindpaw ischaemia produces nitric oxide (NO), which diffuses in the spinal cord to induce spatially spreading potentiation. Using flavoprotein fluorescence imaging, we confirmed that the spreading potentiation in hindpaw responses was induced during ischaemia in the non‐stimulated hindpaw. This spreading potentiation was blocked by spinal application of l‐NAME, an inhibitor of NO synthase (NOS). Furthermore, no spreading potentiation was observed in neural NOS (nNOS) knockout mice. Spinal application of an NO donor was enough to induce cortical potentiation and mechanical hypersensitivity. The spatial distribution of NO during unilateral hindpaw ischaemia was visualized using 4‐amino‐5‐methylamino‐2′,7′‐difluorofluorescein (DAF‐FM). An increase in fluorescence derived from the complex of DAF‐FM with NO was observed on the ischaemic side of the spinal cord. A similar but smaller increase was also observed on the contralateral side. Somatosensory potentiation after hindpaw ischaemia is known to be inhibited by spinal application of LY354740, an agonist of group II metabotropic glutamate receptors (mGluRs). We confirmed that the spinal DAF‐FM fluorescence increases during hindpaw ischaemia were not observed in the presence of LY354740. We also confirmed that approximately half of the nNOS‐positive neurons in the superficial laminae of the dorsal horn expressed mGluR2 mRNA. These results suggest that disinhibition of mGluR2 produces NO which in turn induces a spreading potentiation in a wide area of the spinal cord. Such spreading, along with the consequent non‐specific potentiation in the spinal cord, may trigger neuropathic pain., Key points Neuropathic pain spreads spatially beyond the injured sites, and the mechanism underlying the spread has been attributed to inflammation occurring in the spinal cord.However, the spatial spread of spinal/cortical potentiation induced by conduction block of the peripheral nerves can be observed prior to inflammation.In the present study, we found that spreading potentiation and hypersensitivity acutely induced by unilateral hindpaw ischaemia are nitric oxide (NO)‐dependent and that NO is produced by ischaemia and quickly diffuses within the spinal cord.We also found that NO production induced by ischaemia is not observed in the presence of an antagonist for group II metabotropic glutamate receptors (mGluRs) and that neuronal NO synthase‐positive dorsal horn neurons express group II mGluRs.These results suggest strongly that NO‐mediated spreading potentiation in the spinal cord is one of the trigger mechanisms for neuropathic pain.

The yips, an involuntary movement impediment that affects performance in skilled athletes, is commonly described as a form of task-specific focal dystonia or as a disorder lying on a continuum with focal dystonia at one end (neurological) and chocking under pressure at the other (psychological). However, its etiology has been remained to be elucidated. In order to understand sensorimotor cortical activity associated with this movement disorder, we examined electroencephalographic oscillations over the bilateral sensorimotor areas during a precision force task in athletes with yips, and compared them with age-, sex-, and years of experience-matched controls. Alpha-band event-related desynchronization (ERD), that occurs during movement execution, was greater in athlete with yips as compared to controls when increasing force output to match a target but not when adjusting the force at around the target. Event-related synchronization that occurs after movement termination was also greater in athletes with yips. There was no significant difference in task performance between groups. The enhanced ERD is suggested to be attributed to dysfunction of inhibitory system or increased allocation of attention to the body part used during the task. Our findings indicate that sensorimotor cortical oscillatory response is increased during movement initiation in athletes with yips.

Background Nasogastric tubes can be easily inserted in patients under general anesthesia. However, for difficult cases, insertion techniques that can be used in routine clinical practice are limited. SUZY forceps are designed for the removal of pharyngolaryngeal foreign bodies under guidance of a McGrath videolaryngoscope. We hypothesized that using SUZY forceps under McGrath videolaryngoscopic guidance may facilitate nasogastric tube insertion and tested this in a randomized controlled trial. Methods Adult patients who underwent gastrointestinal or hepato-pancreato-biliary surgery were randomly allocated to 2 groups; the SUZY group and the Magill group. Patients, nurses, and all clinical staff except for the attending anesthesiologist were blinded to group assignment throughout the study. After anesthesia induction, insertion of the nasogastric tube was performed by skilled anesthesiologists with either SUZY or Magill forceps according to group allocation under McGrath videolaryngoscopic guidance. The primary endpoint was insertion time which was defined as the time required to advance the nasogastric tube by 55 cm from the nostril. Secondary endpoints were the success rates of the nasogastric tube insertion, which were defined as a 55-cm advancement from the nostril at the 1st, 2nd, and 3rd attempt, proper insertion rate, the severity of pharyngolaryngeal complications, and hemodynamic parameters during nasogastric tube insertion. Results Sixty patients were randomized and none of these patients were excluded from the final analysis. The median [interquartile range] insertion time was 25 [18-33] seconds in the SUZY group, and 33 [21-54] seconds in the Magill group (P = .02). Success rates were not different between the groups (97% and 80% in the SUZY and Magill group at 1st attempt, respectively, P = .10). Both, the severity score of the mucosal injury and the severity of sore throat were higher in the Magill than in the SUZY group, whereas the degree of hoarseness did not differ between the 2 groups. Hemodynamic parameters were not significantly different between the groups. Conclusion Using SUZY forceps under McGrath videolaryngoscopic guidance reduced the time required to insert a nasogastric tube and the severity of pharyngolaryngeal complications, when compared to using Magill forceps.

Opioid-related postoperative nausea and vomiting should not occur following remifentanil administration because of its relatively short time to elimination. However, studies have indicated that the incidence of postoperative nausea and vomiting associated with remifentanil is similar to that with other opioids. Hence, we aimed to determine whether intraoperative remifentanil itself is associated with postoperative nausea and vomiting when postoperative pain is managed without opioid use. In this prospective pilot study, 150 patients who underwent unilateral upper limb surgery under general anesthesia with brachial plexus block were included. Patients in the remifentanil and control groups received 0.5 µg/kg/min remifentanil and saline, respectively. Postoperative pain was managed using a brachial plexus block, non-steroidal anti-inflammatory drugs, and acetaminophen. The presence of postoperative nausea and vomiting within the first 24 h after anesthesia was assessed by an evaluator blinded to patient allocation. Eight patients were excluded from the final analysis, resulting in 72 and 70 patients in the remifentanil and control groups, respectively. Postoperative nausea and vomiting within 24 h after surgery occurred in 11 and 9 patients in the remifentanil and control groups, respectively. These data suggest that remifentanil use only minimally affects the incidence of postoperative nausea and vomiting under sevoflurane anesthesia. UMIN Clinical Trials Registry identification number: UMIN000016110.

The study aim was to compare the influence of an auditory stimulus (AS) on anticipatory postural adjustments (APAs) between young and older adults during a choice step reaction. Sixteen young and 19 older adults stepped forward in response to a visual imperative stimulus of an arrow. We used a choice reaction time (CRT) task and a Simon task which consisted of congruent and incongruent conditions. The direction of the presented arrow and its spatial location matched in the congruent condition while they did not in the incongruent condition. The AS was presented randomly and simultaneously with the visual stimulus. Incorrect weight shifts before lifting off the foot, termed APA errors, stepping errors, temporal parameters, and APA amplitudes were analyzed. The APA error rate was higher in trials with than without AS in all task conditions for the older group, while this increase occurred only in the incongruent condition for the young group. The stepping error rate was also increased in the presence of AS in the incongruent condition for the older group. Reaction times were faster with AS in both groups. The APA amplitude of erroneous APA trials became larger with AS in the incongruent condition for both groups, and this effect appeared greater for the older group. The effect of AS on APAs is larger in the elderly during a choice step reaction. In the presence of incongruent visual information, this effect becomes even greater, potentially inducing not only APA errors but also stepping errors.

Aim The kinetics of propofol are influenced by cardiac output. The aim of this study was to examine changes in blood propofol concentrations during phaeochromocytoma surgery using target-controlled infusion (TCI) anaesthesia with propofol. Methods This is a prospective observational study. Ten patients with phaeochromocytoma who underwent unilateral adrenalectomy were included. Cardiac output was measured using an arterial pressure-based cardiac output analysis method. The target blood propofol concentrations were adjusted to maintain an approximate bispectral index (BIS) value of 40 before initiating surgery. The settings remained constant during surgery. Blood samples for propofol concentrations were collected from the radial artery at seven time points: two before tumour manipulation (T1, 2), two during tumour manipulation (T3, 4), and three after tumour vein ligation (T4–7). BIS values, the arterial pressure cardiac index (APCI) and haemodynamic parameters were measured at the same time points as the blood samples. The prop-ratio was calculated by dividing blood propofol concentrations by target concentrations of TCI. Results APCI increased during tumour manipulation and after tumour vein ligation. The prop-ratio was reduced significantly by approximately 40% and showed a significant negative correlation with APCI. BIS values increased significantly and showed a significant negative correlation with the prop-ratio. Conclusion The increased APCI during tumour manipulation and after tumour vein ligation was associated with markedly reduced blood propofol concentrations. These results reveal that significant decreases in the anaesthetic effect may be observed in patients undergoing phaeochromocytoma surgery even if TCI anaesthesia is used with propofol.

Beta-band (15–30 ​Hz) corticomuscular and intermuscular coherences are important markers of the corticospinal interaction. The purpose of this study was to investigate whether amount of visual feedback during an isometric pinch grip contraction would influence these coherences in young and elderly adults. Thirty-three healthy young and elderly subjects performed pinch grip force-matching task with right thumb and index finger, while scalp electroencephalogram (EEG) and electromyogram (EMG) from the first dorsal interosseous (FDI) and abductor pollicis brevis (APB) muscles were recorded. The amount of visual feedback was altered by manipulation of visual gain (low and high). Beta-band corticomuscular coherence was computed between EEG over the sensorimotor cortex and EMG from the FDI muscle and between EEG and EMG from the APB muscle (EEG-FDI and EEG-APB coherences). Also, beta-band intermuscular coherence was computed between EMG signals from the FDI and APB muscles (EMG-EMG coherence). Task performance was quantified as standard deviation (SD) of force and mean force error (MFE). EEG-FDI coherence was larger at high than low visual gain in the elderly but not in the young subjects, whereas there was no effect of age or visual gain on EEG-APB coherence. EMG-EMG coherence was smaller at high than low visual gain in the young and elderly subjects. The MFE was smaller at high than low visual gain in the young and elderly subjects, but the SD of force was smaller at high than low visual gain only in the young subjects. These results suggest that the effect of aging on beta-band coherence depends on the amount of visual feedback and further that visual feedback modulates beta-band corticomuscular and intermuscular coherences differently.

Transcranial static magnetic stimulation (tSMS) is a new technique of non-invasive brain stimulation using a small, high-powered neodymium magnet placed on the scalp. It can reduce cortical excitability below the magnet. The aim of this study was to investigate the effect of tSMS on the intracortical excitability of the primary motor cortex (M1) contralateral to the M1 where the magnet was placed. Fourteen right-handed healthy subjects participated in this experiment. TSMS was applied over the left M1 for 20 min. Single-pulse and paired-pulse transcranial magnetic stimulation (TMS) was applied over the right M1 to assess corticospinal excitability, short-latency intracortical inhibition (SICI), and intracortical facilitation (ICF) before and immediately after the intervention. ICF decreased significantly after tSMS, whereas corticospinal excitability and SICI did not change. This study suggests that tSMS applied over the M1 for 20 min has a remote modulatory effect on the interneuronal facilitatory circuit in the contralateral M1. The ability of tSMS to modulate neuronal activities in the remote cortex could expand the possibility of its clinical use.

Age-induced decline in the ability to perform daily activities is associated with a deterioration of physical parameters. Changes occur in neuromuscular system with age; however, the relationship between these changes and physical parameters has not been fully elucidated. Therefore, in this study, we aimed to determine the relationship between neuromuscular system evaluated using a coherence analysis of the leg muscles and physical parameters in community-dwelling healthy elderly adults. The participants were required to stand still in bipedal and unipedal stances on a force plate. Then, electromyography (EMG) was recorded from the tibialis anterior (TA) and medial and lateral gastrocnemius (MG/LG) muscles, and intermuscular coherence was calculated between the following pairs: TA and MG (TA–MG), TA and LG (TA–LG), and MG and LG (MG–LG). Furthermore, gait speed, unipedal stance time, and muscle mass were measured. EMG–EMG coherence for the MG–LG pair was significantly greater in the unipedal stance task than in the bipedal one (p = .001). Multiple linear regression analysis revealed that the muscle mass of the leg was negatively correlated with the change in the β-band coherence for the MG–LG pair from bipedal to unipedal stance (R2 = 0.067, standard β = −0.345, p = .044). As the β-band coherence could reflect the corticospinal activity, the increased β-band coherence may be a compensation for the smaller muscle mass, or alternatively may be a sign of changes in the nervous system resulting in the loss of muscle mass.

Background Radiation enteritis following radiotherapy targeting the abdomen occasionally causes ulcers or ileus, which can be difficult to treat and usually progressive and refractory, significantly degrading the patient’s quality of life. Case presentation A 58-year-old woman had undergone surgery for cervical cancer approximately 21 years ago. During treatment, she had also received radiotherapy targeting the pelvis and stomach. She presented with complaints of vomiting and lower abdominal pain and was subsequently diagnosed with multiple gastric ulcers, enterocolitis, and paralytic ileus due to late radiation-induced sequelae. We reasoned that visceral sympathetic block would improve the abdominal symptoms; therefore, we performed a splanchnic nerve block and an inferior mesenteric artery plexus block. As predicted, these block procedures improved the symptoms. Conclusions Radiation enteritis is an iatrogenic disease, and there is no established treatment for intractable cases. However, visceral sympathetic nerve block may show efficacy as a potential therapy for radiation enteritis-associated abdominal pain and ileus.

We investigated the influence of transcranial static magnetic field stimulation (tSMS) over the supplementary motor area (SMA) on anticipatory postural adjustments (APAs), in which the activation of the postural muscles of the legs and trunk that control standing posture precedes the activation of the prime mover muscles during rapid shoulder flexion movement. Eighteen subjects performed a self-paced rapid shoulder flexion task before, during, and after tSMS. Electromyogram (EMG) activity was recorded from the deltoid anterior (AD) as the prime mover muscle and the biceps femoris (BF) as the postural muscle during the task. The EMG latency difference (ΔEMG onset) between the two muscles was calculated by subtracting the EMG burst onset of the BF from that of the AD. The ΔEMG onset was significantly shortened, but center-of-pressure parameters were not affected after tSMS stimulation. These findings suggest that tSMS applied over the SMA could inhibitively modulate APAs function.

Transcranial static magnetic stimulation (tSMS) is a recently introduced noninvasive brain stimulation technique that can modulate brain excitability. Here, we investigated a hypothesis that motor learning would be altered by tSMS applied to the primary motor cortex (M1). For motor task, we chose a serial reaction time task consisting of sequential trials and random trials in which the visual cue doesn’t play out a repeating pattern of positions to evaluate an implicit motor learning, where the M1 is a key structure for skill acquisition and early consolidation. Forty-four healthy right-handed volunteers participated in the present study. TSMS was placed over the right M1 or dorsolateral prefrontal cortex (DLPFC). The control group received Sham stimulation over the right M1. Reaction times (RTs) of left hand were analyzed before (Pre session) and after (Post session) practice to examine online learning, and were also assessed 24 h later to examine offline learning (Cons session). The results showed that the RTs became faster in Post than Pre session regardless of the stimulation location. Interestingly, the RTs were significantly faster with the M1 stimulation than the DLPFC or Sham stimulation in Cons session. There was not significant difference in error rate among sessions or stimulation locations. These findings suggest that the modulation of the M1 using tSMS can enhance offline motor learning in an implicit task.

Variability is an inherent feature of the motor output. Although low-frequency oscillations (0.5 Hz) are the most important contributor to the variability of force during single-joint isolated force tasks, it remains unclear whether they contribute to the variability of a more complex task, such as a voluntary postural task.Do low-frequency oscillations contribute to postural sway (center of pressure (COP) variability) when participants attempt to voluntarily maintain posture in a forward leaning position?Fourteen healthy young adults performed two tasks: 1) stand quietly (control condition); 2) leaned their body forward to 60% of their maximum lean distance by dorsiflexing the ankle joint. We recorded the COP and electromyographic (EMG) activity from the medial gastrocnemius (MG) and soleus (SL) muscles. We quantified the following: 1) COP variability as the standard deviation (SD) of anteroposterior COP displacements; 2) modulation of COP as the power in COP displacements from 0 to 2 Hz; 3) modulation of EMG bursting as the power in the rectified and smoothed EMG from 0 to 2 Hz; 4) modulation of the interference EMG as the power in the EMG from 10 to 35 and 35-60 Hz.The SD of COP displacements related to the COP oscillations0.5 Hz in both quiet standing and lean tasks. However, only for the lean task, the0.5 Hz COP oscillations related to the EMG burst oscillations0.5 Hz of the MG muscle. The EMG burst oscillations0.5 Hz of the MG muscle further related to the interference EMG oscillations from 35 to 60 Hz for the lean task.Voluntary control of forward leaning posture relates to low-frequency neural inputs to the MG muscle.

Plantar flexor muscles play a crucial role in maintaining balance during quiet standing. The purpose of this study was to investigate the effect of their fatigue on common input to these muscles, using a coherence analysis. Thirteen healthy young male adults stood quietly before and after a fatigue protocol consisting of a heel raise exercise. Center of pressure (COP) displacement and electromyograms (EMGs) from the bilateral medial gastrocnemius and soleus muscles were recorded. EMG-EMG coherences between the bilateral homologous muscles (bilateral coherence) and within the unilateral muscles (unilateral coherence) in the right leg were calculated. Anteroposterior and mediolateral COP speeds, mediolateral COP SD, and 95% confidence ellipse area were larger in post- than pre-fatigue condition. Bilateral and unilateral coherences in delta band, that reflect comodulation of muscle activation, and bilateral coherence in alpha band, that is supposedly associated with the subcortical inputs, were smaller in post- than pre-fatigue condition. Unilateral coherences in alpha and beta band, reflecting physiological tremor and corticospinal drive, respectively, were not different between pre- and post-fatigue conditions. It is suggested that the low-frequency common input to the plantar flexor muscles is reduced following the fatiguing contraction during quiet standing, likely by a change in the postural control strategy.

Aging can impair an ability to lean the body forward to the edge of the base of support. Here, we investigated, using a coherence analysis, common inputs to bilateral and unilateral plantar flexor muscles to test a hypothesis that the age-related impairment would be related to strong synchronous bilateral activation and reduced cortical control of these muscles. Healthy young (n = 14) and elderly adults (n = 19), who were all right-foot dominant, performed quiet standing task and tasks that required the subjects to lean their body forward to 35 and 75% of the maximum lean distance. The electromyogram was recorded from the bilateral medial gastrocnemius (MG) and soleus (SL) muscles. We analyzed delta-band coherence, that reflects comodulation of muscle activity, between the bilateral homologous muscles (MG-MG and SL-SL pairs). The origin of this bilateral comodulation is suggested to be the subcortical system. Also, we examined beta-band coherence, that is related to the corticospinal drive, between the unilateral muscles (MG-SL pair) in the right leg. Results indicated that the bilateral delta-band coherence for the MG-MG pair was significantly smaller in the 75% forward lean than quiet standing and 35% forward lean tasks for the young adults (quiet: p = 0.036; 35%: p = 0.0011). The bilateral delta-band coherence for the SL-SL pair was significantly smaller in the 75% forward lean than 35% forward lean task for the young adults (p = 0.027). Furthermore, the unilateral beta-band coherence was larger in the forward lean than quiet standing task for the young adults (35%: p < 0.001; 75%: p = 0.029). Contrarily, the elderly adults did not demonstrate such changes. These findings suggest the importance of decreasing the synchronous bilateral activation and increasing the unilateral cortical control of the plantar flexor muscles for the successful forward postural lean performance, and that aging impairs this modulatory ability.

The voluntary step execution task is a popular measure for identifying fall risks among elderly individuals in the community setting because most falls have been reported to occur during movement. However, the neurophysiological functions during this movement are not entirely understood. Here, we used electromyography (EMG) to explore the relationship between EMG-EMG coherence, which reflects common oscillatory drive to motoneurons, and motor performance associated with stepping tasks: simple reaction time (SRT) and choice reaction time (CRT) tasks. Ten healthy elderly adults participated in the study. Participants took a single step forward in response to a visual imperative stimulus. EMG-EMG coherence was analyzed for 1000 ms before the presentation of the stimulus (stationary standing position) from proximal and distal tibialis anterior (TA) and soleus (SOL) muscles. The main result showed that all paired EMG-EMG coherences in the alpha and beta frequency bands were greater in the SRT than the CRT task. This finding suggests that the common oscillatory drive to the motoneurons during the SRT task occurred prior to taking a step, whereas the lower value of corticospinal activity during the CRT task prior to taking a step may indicate an involvement of inhibitory activity, which is consistent with observations from our previous study (Watanabe et al., 2016). Furthermore, the beta band coherence in intramuscular TA tended to positively correlate with the number of performance errors that are associated with fall risks in the CRT task, suggesting that a reduction in the inhibitory activity may result in a decrease of stepping performance. These findings could advance the understanding of the neurophysiological features of postural adjustments in elderly individuals., Article, Frontiers in Human Neuroscience 12 : 50, (2018)

To investigate the effects of aging on coordination of plantar flexor muscles during bipedal and unipedal stances, we examined a relationship between the center of pressure sway and electromyographic activity of these muscles, and also the common neural input, using a coherence analysis. Healthy young and elderly adults were asked to perform bipedal and unipedal standing. The electromyograms were recorded unilaterally from the medial and lateral gastrocnemius (MG and LG) and soleus (SL) muscles, and the common input was analyzed for MG–LG, MG–SL, and LG–SL pairs in two frequency bands: a delta band, that is associated with force variability, and a beta band, that could reflect the corticospinal drive. Main results indicated that the MG and SL muscles worked for lateral sway, while the LG muscle worked for medial sway during the unipedal stance. The delta-band coherence for the MG–SL pair and the beta-band coherences for all the pairs were larger during the unipedal than bipedal stance for both groups. The delta-band coherence for the MG–SL pair was larger for the elderly than young adults during the unipedal stance. In addition, the beta-band coherence for the MG–SL pair was larger than the other pairs during the unipedal stance for the elderly. These findings suggest that the oscillatory activity between the MG and SL muscles is strongly involved in the control of unipedal stance, and aging would increase the cortical drive to these muscles to deal with the postural sway that could be affected by forces generated cooperatively by them.

Start hesitation in patients with Parkinson's disease (PD) occurs predominantly during distractive and conflictual situations. The aim of this study was to investigate how differently an auditory stimulus (AS) influences execution function and execution time during a cognitively demanding stepping task in PD patients as compared to healthy controls. PD patients and healthy controls stepped forward in response to a visual imperative stimulus of an arrow. We applied a Simon task that comprised congruent and incongruent conditions. Direction and location of the arrow matched in the congruent condition, while they didn't in the incongruent condition. AS were randomly and simultaneously presented with the visual stimulus. An error in the direction of an anticipatory postural adjustment (APA), termed an APA error, and temporal parameters (reaction onset of APA and APA duration) were analyzed. As a result, the AS increased the APA error rate in the control group regardless of the condition, but they did not influence it in the PD group. The AS also speeded the reaction onset in both groups regardless of the condition. The APA duration was prolonged by the AS for the control group, while it was unaffected by the AS for the PD group in both conditions. These findings indicate that AS could facilitate a step initiation, conceivably by facilitating a stimulus identification process and increasing attentional control of stepping behavior, without influencing a decision-making process even in a cognitively demanding condition in patients with PD.

Background Postoperative pain management after upper limb surgery is important for preventing adverse events that can prolong hospital stay and cause readmission. This study aimed to identify the risk factors associated with rescue analgesic use on the first postoperative day after upper limb surgery performed under single-injection brachial plexus block (BPB). Findings We retrospectively analyzed records from 930 patients who underwent upper limb surgery under a single-injection BPB. Postoperatively, patients were administered oral loxoprofen regularly and rescue analgesics when analgesia was insufficient. We assessed the association between patient, surgical information, and rescue analgesic use on the first day after surgery (from 7:00 PM on the day of surgery to 7:00 AM on the first postoperative day), using a logistic regression model. Multivariate analysis revealed a significant association between rescue analgesic use and bone surgery, in particular, osteotomy, ligament repair and reconstruction, osteosynthesis, treatment for an amputated digit, and surgical duration. Conclusion Bone surgery (osteotomy, ligament repair and reconstruction, osteosynthesis, treatment for an amputated digit) and a longer operative time were risk factors for rescue analgesic use for treating postoperative pain after upper limb surgery performed under single-injection BPB.

Choice reaction requires response conflict resolution, and the resolution processes that occur during a choice stepping reaction task undertaken in a standing position, which requires maintenance of balance, may be different to those processes occurring during a choice reaction task performed in a seated position. The study purpose was to investigate the resolution processes during a choice stepping reaction task at the cortical level using electroencephalography and compare the results with a control task involving ankle dorsiflexion responses. Twelve young adults either stepped forward or dorsiflexed the ankle in response to a visual imperative stimulus presented on a computer screen. We used the Simon task and examined the error-related negativity (ERN) that follows an incorrect response and the correct-response negativity (CRN) that follows a correct response. Error was defined as an incorrect initial weight transfer for the stepping task and as an incorrect initial tibialis anterior activation for the control task. Results revealed that ERN and CRN amplitudes were similar in size for the stepping task, whereas the amplitude of ERN was larger than that of CRN for the control task. The ERN amplitude was also larger in the stepping task than the control task. These observations suggest that a choice stepping reaction task involves a strategy emphasizing post-response conflict and general performance monitoring of actual and required responses and also requires greater cognitive load than a choice dorsiflexion reaction. The response conflict resolution processes appear to be different for stepping tasks and reaction tasks performed in a seated position.

A loud auditory stimulus (LAS) presented simultaneously with a visual imperative stimulus can reduce reaction time (RT) by automatically triggering a movement prepared in the brain and has been used to investigate a movement preparation. It is still under debate whether or not a response is prepared in advance in RT tasks involving choice responses. The purpose of the present study was to investigate the preparatory state of anticipatory postural adjustments (APAs) during a choice reaction step initiation. Thirteen young adults were asked to step forward in response to a visual imperative stimulus in two choice stepping conditions: (i) the responding side is not known and must be selected and (ii) the responding side is known but whether to initiate or inhibit a step response must be selected. LAS was presented randomly and simultaneously with the visual imperative stimulus. LAS significantly increased the occurrence rates of inappropriately initiated APAs while reducing the RTs of correct and incorrect trials in both task conditions, demonstrating that LAS triggered the prepared APA automatically. This observation suggests that APAs are prepared in advance and withheld from release until the appropriate timing during a choice reaction step initiation. The preparatory activity of APAs might be modulated by the inhibitory activity required by the choice tasks. The preparation strategy may be chosen for fast responses and is judged most suitable to comply with the tasks because inappropriately initiated APAs can be corrected without making complete stepping errors.

Background Respiratory muscle strength has been used as a tool for evaluating respiratory rehabilitation in chronic obstructive pulmonary disease. However, mouth pressure measurement evaluated by maximum expiratory mouth pressure (PEmax) or inspiratory mouth pressure (PImax) offers an indirect method for measuring respiratory muscle strength. We demonstrated the evaluation of diaphragm contractility using a mechanomyogram (MMG), which is the mechanical signal generated by the motion of the diaphragm induced by the electric stimulation of the phrenic nerve. Methods Study participants were 21 young and 20 elderly subjects with no symptoms of respiratory disease. The elderly subjects were divided into non-smoker or smoker groups. The smoker group was defined as subjects having a Brinkman Index of greater than 300. We measured basic spirometric parameters, mouth pressure (PEmax, PImax), and diaphragmatic MMG. Results Diaphragmatic MMG showed more clear contrast between young subjects and elderly non-smoker or smoker subjects than the conventional method for respiratory muscle contraction (PEmax, PImax). In addition, the diaphragmatic MMG strongly correlated with inspiratory muscle strength. Conclusions Diaphragmatic MMG may reflect diaphragmatic contractility more directly and sensitively than the conventional method.

We describe a case in which an anatomic diagnosis was useful for diagnosing and estimating the cause of femoral nerve palsy following gynecologic surgery. A 49-year-old female received general and epidural anesthesia for radical ovarian cancer surgery. Although injection pain was noted in the left medial shin with 1 % mepivacaine administered as a test dose, the catheter was left indwelling because it improved her symptoms. The surgery, which lasted 195 min, was performed in the lithotomy position, and a self-retained retractor was used to gain a good surgical field. Postoperatively, the patient complained of difficulty in stretching her knee joint and left lower limb paresthesia that did not improve after stopping continuous epidural administration. A spinal cord injury related to epidural anesthesia was suspected because the sites of sensory impairment and epidural injection pain were the same; however, the patient had greater weakness of the quadriceps muscle than the iliopsoas, and no other muscle weakness was observed. These findings and previous reports suggest that her femoral nerve palsy was caused by compression of the inguinal ligament from the self-retaining retractor and lithotomy position. Twenty months after surgery, her muscle strength had fully recovered.

We describe a very rare case of an indwelling central venous catheter (CVC) through the left internal jugular vein that perforated the superior vena cava (SVC) wall postoperatively, although the CVC was placed in the appropriate position preoperatively. Three days after CVC insertion, a chest radiograph showed that the CVC tip had moved from the lower SVC to the upper SVC. Five days after the insertion, computed tomography showed SVC perforation and the resulting hydrothorax. In cases of CVC insertion through the left side, the CVC tip should not be placed in the upper SVC (zone B). Considering individual clinical factors and the indwelling period for the CVC, the left innominate vein (zone C) may be a suitable site for the left-sided CVC tip to reduce the risk of SVC perforation.

Background: Nasogastric tube (NGT) insertion is an easy procedure that can be routinely performed under general anesthesia. However, for difficult cases, there are limited insertion techniques available in routine clinical practice, considering the flexibility of NGTs. The SUZY curved forceps are designed for the removal of pharyngolaryngeal foreign bodies under guidance of the McGRATH MAC (McG) videolaryngoscope. Because McG enables clear visualization of the esophageal inlet, we hypothesized that the SUZY forceps can facilitate easier NGT insertion compared with the conventional Magill forceps under McG guidance and designed a randomized, crossover manikin study to test this hypothesis. Materials and Methods: Ten anesthesiologists participated in this study. Each participant was instructed to insert an NGT using either the SUZY or the Magill forceps under McG guidance. Both types of forceps were used by each participant in a computer-generated random order. The primary outcome measure was the number of “strokes” (1 stroke was defined by a specific sequence of participant actions) required to advance the NGT 30 cm from the starting point. Data are expressed as medians (interquartile ranges [ranges]). Results: The number of strokes required for NGT insertion was fewer in the SUZY group than in the Magill group {7 [7.0–12.5 (5–14)] vs 16.5 [13.5–20.3 (7–22)]; P