Effects of a competitive stressor on motor cortex excitability: a pilot study

Several intervening variables may influence motor evoked potentials (MEP) from transcranial magnetic stimulation (TMS). Among the most common are motor (e.g. executed or intended muscle contraction) and sensory factors. However, little is known about the effects of a well defined stressor on MEPs and thus on central motor control. We studied 11 healthy right‐handed volunteers (five men and six women), aged 21–32 years (mean 25.2 years, SD=3.5). All subjects underwent a 20 min rest and a 20 min stress period (sequence‐controlled, cross‐over design). The stressor employed a competitive videogame. MEPs from the left abductor digiti minimi muscle were obtained immediately after rest and stress. We found that six (54.5 per cent) subjects presented a significant increase (p<0.05) of MEP amplitudes from rest to stress, three (27.3 per cent; p<0.05) decreased, and two (18.2 per cent) did not change. F‐ and M‐waves did not change significantly. Psychological testing (state and trait anxiety inventory, STAI) revealed that individuals who presented an increase in MEP latency scored lower in state and trait anxiety than others, probably indicating a lower vulnerability to stress. We believe that the observed increase in MEP amplitudes, combined with a decrease in MEP latency, can be regarded as neurophysiological evidence of stress‐induced facilitation related to higher excitability of the corticospinal system and/or presynaptic neurons. Copyright © 2000 John Wiley & Sons, Ltd.     

Rapid effects of estrogen and progesterone on tone and spontaneous rhythmic contractions of the rabbit bladder

Previous studies indicate that bladder instability in man may be associated with increased spontaneous rhythmic contractile activity. Ca²⁺ influx plays a central role in smooth muscle contractions, and recent evidence suggests that steroid hormones rapidly affect Ca²⁺ influx. Therefore we tested the hypothesis that estrogen and progesterone modulates spontaneous rhythmic detrusor contractions. Tissues were secured to isometric force (F) transducers in tissue baths and length-adjusted until K⁺-depolarization produced maximum contractions (F_o). Spontaneous rhythmic contractions (SRC) were sampled before and immediately after addition of estradiol or progesterone (10⁻⁵ M) to tissue baths. The average frequency and amplitude of SRC were, respectively, 0.156 Hz and 0.053 F/F_o (n = 24). Estradiol caused an immediate reduction in SRC, such that by 10 min, tone, frequency and amplitude were each reduced by, respectively, 36%, 46% and 47% (n = 7, P < 0.05). However, progesterone caused an immediate weak contraction, and at steady state (10 min), progesterone increased frequency of SRC by 152% but decreased SRC amplitude by 50% (n = 10, P < 0.05). Novel therapies using unique steroids that do not interact with genomic receptors may potentially reduce bladder smooth muscle activity, thereby reducing detrusor instability. Received: 3 December 1998 / Accepted: 4 March 1999     

Type D personality is associated with increased desire for alcohol in response to acute stress

Type D personality (the combination of negative affectivity and social inhibition) is associated with high levels of alcohol consumption. We examined if Type D was associated with higher levels of alcohol use, and if Type D was associated with desire for alcohol in response to a social stressor. In an experimental study, participants (n = 138) completed measures of Type D, stress, and alcohol use. They also took part in a stress‐inducing public speaking task and provided measures of desire for alcohol at baseline, stressor, and recovery. Type D was associated with higher levels of alcohol use, stress, and desire for alcohol at stressor and recovery. Mixed measures analysis of variance demonstrated that there was a significant group effect of Type D (F(1, 136) = 6.86, p < .05) and a significant time × Type D interaction (F(1.50, 204.49) = 3.44, p < .05) on desire for alcohol. Type D individuals exhibited significantly higher levels of desire for alcohol during the stressor and recovery phases, compared to non‐Type D individuals suggesting that Type D individuals may be motivated to consume alcohol in order to cope with stressful situations.     

Pelvic floor muscle exercise for the treatment of female stress urinary incontinence: III. Effects of two different degrees of pelvic floor muscle exercises

Fifty-two women, mean age 45.9 years (24–64) with clinically and urodynamically proven stress urinary incontinence (SUI) were randomly assigned to one of two different pelvic floor muscle (PFM) exercise groups. Both groups performed 8–12 maximal PFM contractions 3 times a day for 6 months. In addition one group exercised with an instructor intensively 45 min once a week performing long-lasting contractions with the supplement of 3–4 fast contractions at the end of each long-lasting contraction. Initially and after 6 months an examination was performed comprising history, urinary leakage index, pad test, maximum urethral closure pressure, functional urethral profile length, and recording of vaginal pressure during PFM contractions. The latter was performed monthly. After the treatment 60% of the intensive exercise (IE) group and 17.3% of the home exercise (HE) group reported to be continent or almost continent (P < .01). Only the IE group demonstrated significant reduction in urine loss; from mean 27 g to 7.1 g (P < .01) and improvement in maximum resting urethral closure pressure (mean improvement 4.6 cm H₂O. P = .02). PFM strength improved with mean 15.5 cm H₂O (P < .01) in the IE group while the HE group improved with 7.4 cm H₂O (P < .01). It is concluded that the results of PFM exercise for female SUI is highly dependent upon the degree and duration of treatment and frequent supervision by the therapist.     

Alteration of sperm parameters and reproductive hormones in Swiss mice via oxidative stress after co-exposure to titanium dioxide and zinc oxide nanoparticles

In this study, Swiss male mice were intraperitoneally administered with titanium dioxide (TiO₂) and zinc oxide (ZnO) nanoparticles (NPs) and their mixture (1:1) at doses between 9.38 and 75 mg/kg for 5 weeks to evaluate reproductive toxicity. Both NPs and their mixture significantly (p < .001) altered sperm motility, reduced sperm numbers and increased abnormalities, while their mixture induced more sperm abnormalities than either TiO₂ NPs or ZnO NPs. Both NPs and their mixture significantly (p < .05) reduced the LH level, while ZnO NPs alone and their mixture (p < .001) increased the testosterone levels at tested doses. The testes of exposed mice showed pathological changes and altered histomorphometrics. TiO₂ NPs and ZnO NPs individually induced a significant (p < .01) reduction in SOD and CAT activities, while the mixture significantly (p < .001) decreased CAT activity and increased SOD activity. TiO₂ NPs alone at 9.38 mg/kg induced a significant (p < .001) reduction in the GSH level, while both NPs and their mixture increased the MDA level significantly (p < .05). The data showed that the mixture had a synergistic interaction to induce testicular damage. Overall, oxidative stress may be involved in the NP-mediated testicular damage observed.     

Female striated urogenital sphincter contraction measured by shear wave elastography during pelvic floor muscle activation: Proof of concept and validation

Aims

Investigation of the function of the striated urogenital sphincter (SUS) is challenging because it is difficult to access and requires invasive measures. Ultrasound shear wave elastography (SWE) is a non‐invasive real‐time technique used to estimate tissue stiffness. As muscle stiffness can be used as an estimate of muscle force, SWE provides an opportunity to study contraction of the peri‐urethral musculature. Validation of SWE to study SUS during functional tasks, such as pelvic floor muscle contractions, is required prior to application in clinical populations.

Methods

Ten healthy females (34[5] years) participated. Stiffness in a region expected to contain the SUS was quantified using SWE at rest and during a pelvic floor muscle contractions performed at 10%, 25%, and 50% of maximal voluntary contraction (MVC). Two repetitions were performed for 10 s.

Results

During contraction, stiffness increased in the region of the SUS in all participants and at all contraction intensities. Multiple regions of increased stiffness were detected, with 95.8% of regions situated ventral to the mid‐urethra within the anatomical area of the SUS. The increase in stiffness was greater for 50% MVC than both 10% and 25% MVC contraction intensities (P < 0.01).

Conclusions

Stiffness increased within the anatomical region of the SUS during voluntary pelvic floor muscle contractions with predictable response to changes in contraction intensity. These observations support the potential for ultrasound SWE to study SUS function non‐invasively.     

Effect of Interpersonal and Cognitive Stressors on Habituation and the Utility of Heart Rate Variability to Measure Habituation

Habituation is a decrease in responding to a repeated stimulus. Operant responding and salivation measure habituation in eating behaviour research. Stress may increase eating by acting as a distractor, yielding spontaneous recovery and prolonging responding for food. Our research tested differences in the ability of cognitive and interpersonal stressors to recover responding for food. We also tested heart rate variability (HRV) as a measure of habituation. Twenty women worked for portions of macaroni and cheese for 15 trials on three separate laboratory visits. Between the 12th and 13th trial, one of three different stressor types (speech, stroop and subtraction) was presented during each visit. HRV was measured continuously throughout the laboratory visits. Responding for food declined across the 12 trials with no difference in rate of habituation by visit (p > 0.8) There was no difference between stressor type in the magnitude of spontaneous recovery after each stressor (p > 0.8). Rates of habituation of HRV variables correlated (p < 0.02) with the rate of operant responding habituation. Cognitive and interpersonal stressors do not differ in their ability to recover reduced responding for food. HRV variables may measure habituation to food similar to operant responding. Copyright © 2014 John Wiley & Sons, Ltd.     

Levator function in nulliparous women

 Pelvic floor muscle exercises are one of the main conservative options for the treatment of female urinary incontinence. Despite this widespread use, there is very little information on `normal' pelvic floor function. In a prospective observational study the authors intended to define the spectrum of normality for pelvic floor function in women, assessing 206 nulliparous women recruited early in their first ongoing pregnancy. Levator function was evaluated using translabial ultrasound: cranioventral displacement of the bladder neck was utilized to quantify levator activity. The presence of a reflex contraction of the external perineal muscles and levator on coughing was registered, as was the strongest of at least three contractions. Only 41 of 206 womjen (20%) had ever been taught pelvic floor exercises by a health professional, and this had been exclusively verbal. Teaching had no influence on levator strength. Spontaneous contractions on request were obtained in 172 women (85%). Advice was necessary in 96 women (47%) in order to obtain an optimal contraction. Reflex muscle activation on coughing was documented in 118 women (57%) and was associated with a stronger contraction (P<0.001). Reported use of the levator muscle on intercourse was strongly associated with increased levator activity (P<0.001). Motivational factors mentioned were boyfriends, mothers, other female relatives and, most commonly, articles in popular magazines, e.g. Cosmospolitan and Cleo. Received: 11 March 2002 / Accepted: 2 July 2002 Acknowledgements The author was supported by a RANZCOG Mayne Nickless Research Fellowship for the duration of this study.     

Urethral pressure response patterns induced by squeeze in continent and incontinent women

Our aim was to compare the urethral pressure response pattern to pelvic floor muscle contractions in 20–27 years old, nulliparous continent women (n = 31) to that of continent (n = 28) and formerly untreated incontinent (n = 59) (53–63 years old) women. These women underwent urethral pressure measurements during rest and repeated pelvic muscle contractions. The response to the contractions was graded 0–4. The young continent women showed a mean urethral pressure response of 2.8, the middle-aged continent women 2.2 (NS vs young continent), and the incontinent women 1.5 (p < 0.05 vs middle-aged continent, p < 0.001 vs young continent). Urethral pressures during rest were significantly higher in the younger women than in both groups of middle-aged women. The decreased ability to increase urethral pressure on demand seen in middle-aged incontinent women compared to continent women of the same age as well as young women seems to be a consequence of a neuromuscular disorder rather than of age.     

Effect of bilateral sacral decentralization on detrusor contractility and passive properties in dog

A series of five dogs underwent complete parasympathetic decentralization through a lumbosacral laminectomy. A full-thickness biopsy was taken from the anterior wall of the bladder before and 12 weeks after surgery. Both mucosa and adventitia were dissected out and muscle layer was cut into several consecutive longitudinal strips. Each strip was mounted in a muscle chamber and frequencyresponse curves were obtained at different pulse duration. Activelpassive force-length relationships were then obtained under condi tions of maximal electrical stimulation (100 V, 2 msec, 40 cps), by stretching the strips in successive increments until length of maximal active force development was reached. Curves were normalized per unit cross-sectional area of muscle. The maximum active stress of the specimens was taken as a measure of bladder contractility, and the rate of exponential increase in passive stress with strain (ratio of deformed to undeformed length) as a measure of detrusor stiffness. Twelve weeks after detrusor decentralization the following changes were found: (1) The frequency that yielded maximum contraction was 10 cps at 2- and 5-;msec pulse duration as compared to 40 cps in controls at every pulse duration. (2) The maximum active stress was 123.9 ± 13.8 vs 244.7 ± 24.7 gm/cm² in controls (p<.001). (3) The level of strain corresponding to the maximal active stress was significantly reduced. (4) The stiffness of the bladder wall was markedly increased; the rate of exponential increase was 4.47 ± 0.63 vs 2.19 ± 0.42 in controls (p<.001). (5) Thickness of the bladder wall was significantly increased (7 ± 1 vs 4 ± 1 mm; p<.001). (6) Histology sections of the specimens demonstrated collagen infiltration in all layers as well as smooth muscle hyperplasia. In summary, the effects of parasympathetic decentralization of the bladder wall are collagen infiltration, increased thickness, increased stiffness, and decreased contractility.     

Early fracture callus displays smooth muscle‐like viscoelastic properties ex vivo: Implications for fracture healing

Cells of early, fibrous callus in bone fractures possess much alpha smooth muscle actin. This callus contracts and relaxes; however, active and passive components of its force production have yet to be defined. We aimed to establish whether passive viscoelastic properties of early soft fracture callus are smooth muscle‐like in nature. Under anesthesia one rib was fractured in rats and calluses removed 7 days later for analysis. Urinary bladder detrusor muscle and Achilles tendon were also resected and analyzed. Force production in these tissues was measured using a force transducer when preparations were immersed in calcium‐free Krebs‐Henseleit solution (pH 7.4, 22°C). Viscoelastic responses were measured in each preparation in response to 50 µN increases and decreases in force after achieving basal tissue tension by preconditioning. Callus, bladder, and tendon all displayed varying, reproducible degrees of stress relaxation (SR) and reverse stress relaxation (RSR) (n = 7 for all groups). Hysteresis was observed in callus, with the first SR response significantly larger than that produced in subsequent stretches (p < 0.05). Callus SR responses were greater than tendon (p < 0.001) but less than bladder (p < 0.001). Callus RSR responses were greater than tendon (p < 0.001), but no significant difference was seen between RSR of callus and bladder. We concluded that early, soft callus displayed significant SR and RSR phenomena similar to smooth muscle tissue, and SR and RSR may be important in maintenance of static tension in early callus by promoting osteogenesis and fracture healing. © 2009 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 27:1508–1513, 2009     

Muscle Activation During Low-Intensity Muscle Contractions With Varying Levels of External Limb Compression

The purpose was to investigate muscle activation during low- intensity muscle contractions with various levels of external limb compression to reduce muscle perfusion/outflow. A series of unilateral elbow flexion muscle contractions (30 repetitive contractions followed by 3 sets x 15 contractions) was performed at 20% of 1RM with varying levels of external compression (0 (without compression), 98, 121, and 147 mmHg external compression) around the upper arm. Electromyography (EMG) signals were recorded from surface electrodes placed on the biceps brachii muscle and analyzed for integrated EMG (iEMG). Maximal voluntary isometric contraction (MVC) decreased similarly during the control (0 mmHg) and 98 mmHg external compression bout (~18%); the decline in MVC with 121 and 147 mmHg external compression was significantly greater (~37%). Muscle activation increased progressively throughout the contraction bout with each level of external compression, but iEMG was significantly greater during 147 mmHg external compression. In conclusion, low-intensity muscle contractions performed with external compression of 147 mmHg appears to alter muscle perfusion/outflow leading to increased muscle activation without decrements in work performed during the contraction bout.

Key points

• Low-intensity muscle contractions with external compression are maintained by greater neural activation.
• It appears there is optimal external compression pressure for increased muscle activation without exaggerated fatigue.
• External compression per arm circumference was related to the neuromuscular response and fatigue.

Key words: Neuromuscular function, EMG, cuff pressure, biceps brachii, ischemia     

Assessment of voluntary pelvic floor muscle contraction in continent and incontinent women using transperineal ultrasound, manual muscle testing and vaginal squeeze pressure measurements

The aims of the study were: (1) to assess women performing voluntary pelvic floor muscle (PFM) contractions, on initial instruction without biofeedback teaching, using transperineal ultrasound, manual muscle testing, and perineometry and (2) to assess for associations between the different measurements of PFM function. Sixty continent (30 nulliparous and 30 parous) and 60 incontinent (30 stress urinary incontinence (SUI) and 30 urge urinary incontinence (UUI)) women were assessed. Bladder neck depression during attempts to perform an elevating pelvic floor muscle (PFM) contraction occurred in 17% of continent and 30% of incontinent women. The UUI group had the highest proportion of women who depressed the bladder neck (40%), although this was not statistically significant (p=0.060). The continent women were stronger on manual muscle testing (p=0.001) and perineometry (p=0.019) and had greater PFM endurance (p<0.001) than the incontinent women. There was a strong tendency for the continent women to have a greater degree of bladder neck elevation than the incontinent women (p=0.051). There was a moderate correlation between bladder neck movement during PFM contraction measured by ultrasound and PFM strength assessed by manual muscle testing (r=0.58, p=0.01) and perineometry (r=0.43, p=0.01). The observation that many women were performing PFM exercises incorrectly reinforces the need for individual PFM assessment with a skilled practitioner. The significant correlation between the measurements of bladder neck elevation during PFM contraction and PFM strength measured using MMT and perineometry supports the use of ultrasound in the assessment of PFM function; however, the correlation was only moderate and, therefore, indicates that the different measurement tools assess different aspects of PFM function. It is recommended that physiotherapists use a combination of assessment tools to evaluate the different aspects of PFM function that are important for continence. Ultrasound is useful to determine the direction of pelvic floor movement in the clinical assessment of pelvic floor muscle function in a mixed subject population.     

Sympathetic inhibition of reflex activation of bladder motility during filling at a physiological-like rate in urethane anaesthetized rats

The mean volume of saline (infused at a physiological-like rate) required to elicit neurogenic rhythmic contractions of the detrusor muscle (micturition threshold) in urethane anaesthetized rats was reduced by reserpine pretreatment, as well as by chemical (6-hydroxydopamine) or surgical sympathectomy (bilateral section of the hypogastric nerves). Propranolol pretreatment had no significant effect on micturition threshold but increased the intraluminal pressure at which the rhythmic contractions occurred. In spinal rats (T12L1) a flat pressure volume curve was obtained with only a minor phasic contractile activity. Propranolol administration or bilateral section of the hypogastric nerves significantly increased the intraluminal pressure response to saline filling in spinal rats. Topical tetrodotoxin increased the intraluminal pressure response to saline filling in control spinal rats but not following propranolol administration or bilateral section of the hypogastric nerves. These findings provide evidence for a sympathetic inhibition of the reflex activation of the detrusor muscle in response to a physiological-like filling of the urinary bladder.     

Function and distribution of autonomic receptors in canine ureteral smooth muscle

There have been only a few reports of the measurement of autonomic receptors in ureteral smooth muscle. Furthermore, it is so difficult to maintain stable spontaneous contractions in the ureter, that either electrical field stimulation or KCl at high concentrations are utilized to induce ureteral contractions in many in vitro ureteral pharmacologic examinations. We used the spiral ureteral strips which generate spontaneous contractions in the ureter in present experiments. Norepinephrine, phenylephrine, clonidine, carbachol, and prostaglandin F_2α enhanced the spontaneous contractile force and/or increased the contractile frequency of spontaneous rhythmic contractions in spirally-incised muscle strips from isolated canine ureters. In contrast, isoproterenol, terbutaline, a β₂-adrenergic agonist, and prostaglandin E₂ reduced the spontaneous contractile force and/or decreased the contractile frequency of spontaneous rhythmic contractions. Dobutamine, a β₁-adrenergic agonist, did not affect significantly the spontaneous rhythmic contractions. The effects of the proslaglandins were not influenced by autonomic antagonists or tetrodotoxin. The existence of α₁ -, α₂ -, and β-adrenoceptors and muscarinic cholinergic receptors were demonstrated in the canine ureter using radioligand techniques. The density of α₁ -receptors binding sites was significantly greater than that of the other receptors examined. Our data show that the sympathetic nervous system is more involved than the para-sympathetic nervous system in canine ureteral contractile activities, and that α – and β -receptors contained in canine ureteral smooth muscle are comprised mainly of the α₁ – and β -subtypes. It is also suggested that prostaglandins directly affect canine ureteral contraction. © 1994 Wiley-Liss, Inc.     

Simulated resistance training during hindlimb unloading abolishes disuse bone loss and maintains muscle strength

This study was designed to determine the effectiveness of simulated resistance training (SRT) without weight bearing in attenuating bone and muscle loss during 28 day hindlimb unloading (HU) in mature male rats. An ambulatory control group (CC) and four groups of HU rats were used: HU, HU + anesthesia (ANHU), HU + eccentric muscle contractions (HU + ECC), and HU + isometric and eccentric muscle contractions (HU + ISO/ECC). Animals in the two SRT groups were trained once every other day at 100% daily peak isometric torque (P₀). HU resulted in significantly lower plantarflexor muscle mass (?33% versus CC) and reduced isometric strength (?10%), which reductions were partially attenuated in both training groups. Significantly reduced total and cancellous volumetric bone mineral density (vBMD) and total bone mineral content (BMC) at the proximal tibia metaphysis (PTM) also was evidenced in HU and ANHU groups compared with both SRT groups (p < .05). Training resulted in greater increases in cortical bone mass and area compared with all other groups (p < .05). Fourfold higher material properties of PTM cancellous bone were demonstrated in SRT animals versus HU or CC animals. A significant reduction in midshaft periosteal bone formation rate (BFR) in the HU group (?99% versus CC) was completely abolished in HU + ECC (+656% versus CC). These results demonstrate that high‐intensity muscle contractions, independent of weight‐bearing forces, can effectively mitigate losses in muscle strength and provide a potent stimulus to bone during prolonged disuse. © 2010 American Society for Bone and Mineral Research.     

Patterns of Treatment Disengagement and Personality Traits Associated With Posttraumatic Stress Disorder in Recent‐Era U.S. Veterans Receiving Cognitive Processing Therapy

Low treatment engagement is a barrier to implementation of empirically supported treatments for posttraumatic stress disorder (PTSD) among veterans. Understanding personality traits that predict dropout may help focus attempts to improve engagement. The current study included 90 veterans who served in recent conflicts in Iraq and/or Afghanistan and participated in a trial of cognitive processing therapy for PTSD. Goals were to characterize (a) personality correlates of PTSD, (b) patterns of engagement (i.e., attendance and homework completion), and (c) personality correlates of reduced engagement. Higher levels of PTSD symptoms were associated with a range of characteristics, including affective lability, r = .44 p < .001; anxiety, r = .38, p < .001; identity problems, r = .57, p < .001; intimacy problems, r = .34, p = .001; low affiliation, r = .33, p = .002; oppositionality, r = .36, p = .001; restricted expression, r = .35, p = .001; and suspiciousness, r = .50, p < .001. Notably, veterans with worse PTSD symptoms endorsed more cognitive dysregulation, r = .40, p < .001; and less insecure attachment, r = .14, p = .190, than expected. Only 52.2% of veterans completed the 12‐session course of treatment and 31.0% of participants completed fewer than six sessions. Personality traits did not predict attendance or homework completion. Disengagement continues to be a significant issue in trauma‐focused treatment for veterans with PTSD. Understanding veteran‐level factors, such as personality traits, may be useful considerations for future research seeking to understand and improve engagement.     

Effects of treadmill running on rat gastrocnemius function following botulinum toxin A injection

Exercise can improve and maintain neural or muscular function, but the effects of exercise in physiological adaptation to paralysis caused by botulinum toxin A has not been well studied. Twenty‐four rats were randomly assigned into control and treadmill groups. The rats assigned to the treadmill group were trained on a treadmill three times per week with the running speed set at 15 m/min. The duration of training was 20 min/session. Muscle strength, nerve conduction study and sciatic functional index (SFI) were used for functional analysis. Treadmill training improved the SFI at 2, 3, and 4 weeks (p = 0.01, 0.004, and 0.01, respectively). The maximal contraction force of the gastrocnemius muscle in the treadmill group was greater than in the control group (p < 0.05). The percentage of activated fibers was higher in the treadmill botox group than the percentage for the control botox group, which was demonstrated by differences in amplitude and area of compound muscle action potential (CMAP) under the curve between the groups (p < 0.05). After BoNT‐A injection, treadmill improved the physiological properties of muscle contraction strength, CMAP amplitude, and the recovery of SFI. © 2011 Orthopaedic Research Society Published by Wiley Periodicals, Inc. J Orthop Res 30:319–324, 2012     

Suppression of Uninhibited Rectal Detrusor by Functional Magnetic Stimulation of Sacral Root

Abstract

Purpose. To demonstrate the effect of sacral magnetic stimulation (MS) on the uninhibited rectal detrusor aiming at suppression of unstable rectal contractions.

Methods. The study was comprised of 6 patients (3 women, 3 men, ages between 32 and 49 years) with supracanal spinal cord injury who complained of fecal incontinence. Rectal sensation for defecation was felt after the onset of involuntary detrusor contraction in 4 patients and not perceived in 2. Rectal and rectal neck pressures were normal. Rectal hyperreflexia was provoked by rapid saline infusion into the rectum (1 00 to 150 ml; 15 ml/s). Sacral MS was effected by a magnetic coil and a stimulator. The coil was applied to the back between L-4 and L-5.

Results. During the provocative saline test, the rectal pressure showed a significant increase (p < .001) and the subjects evacuated the infused saline involuntarily; the rectal neck pressure showed no significant change (p > .05). Intermittent MS during the induced rectal pressure rise using 70% of maximal intensity (i.e., 175 Joules per pulse, 40 Hz frequency, and 2 second burst length with 2 seconds off) affected rectal pressure decline (p < .01) and no saline evacuation.

Conclusions. Sacral MS produced inhibition of provoked rectal hyperreflex contractions in patients with supraconal cord injuries. The method is simple, easy, noninvasive, and with no adverse effects.     

Relationship between abdominal and pelvic floor muscle activation and intravaginal pressure during pelvic floor muscle contractions in healthy continent women

AIM: Activation of the abdominal muscles might contribute to the generation of a strong pelvic floor muscle contraction, and consequently may contribute to the continence mechanism in women. The purpose of this study was to determine the abdominal muscle activation levels and the patterns of muscle activity associated with voluntary pelvic floor muscle (PFM) contractions in urinary continent women. METHODS: Fifteen healthy continent women participated. They performed three maximal contractions of each of the four abdominal muscles and of their PFMs while in supine. Abdominal and PFM activity was recorded using electromyography (EMG), and intravaginal pressure was recorded using a custom modified Femiscan probe. RESULTS: During voluntary maximal PFM contractions, rectus abdominus was activated to 9.61 (+/-7.42)% maximal voluntary electrical activity (MVE), transversus abdominus was activated to 224.30(+/-47.4)% MVE, the external obliques were activated to 18.72(+/-13.33)% MVE, and the internal obliques were activated to 81.47(+/-63.57)% MVE. A clear pattern of activation emerged, whereby the transversus abdominus, internal oblique, and rectus abdominus muscles worked with the PFM in the initial generation of maximal intravaginal pressure. PFM activity predominated in the initial rise in lower vaginal pressure, with later increases in pressure (up to 70% maximum pressure) being associated with the combined activation of the PFM, rectus abdominus, internal obliques, and transverses abdominus. These abdominal muscles were the primary source of intravaginal pressure increases in the latter 30% of the task, whereas there was little increase in PFM activation from this point on. The external oblique muscles showed no clear pattern of activity, but worked at approximately 20% MVE throughout the PFM contractions, suggesting that their role may be predominantly in postural setting prior to the initiation of intravaginal pressure increases. CONCLUSIONS: Defined patterns of abdominal muscle activity were found in response to voluntary PFM contractions in healthy continent women.