Anal Sphincter EMG Research Articles

Fecal incontinence patients categorized based on anal pressure and electromyography: Anal sphincter damage and clinical symptoms.

Disruption of external anal sphincter muscle (EAS) is an important factor in the multifactorial etiology of fecal incontinence (FI). We categorize FI patients into four groups based on the location of lesion in neuromuscular circuitry of EAS to determine if there are differences with regards to fecal incontinence symptoms severity (FISI) score, age, BMI, obstetrical history, and anal sphincter muscle damage. Female patients (151) without any neurological symptoms, who had undergone high-resolution manometry, anal sphincter EMG, and 3D ultrasound imaging of the anal sphincter were assessed. Patients were categorized into four groups: Group 1 (normal)-normal cough EMG (>10 μV), normal squeeze EMG (>10 μV), and normal anal squeeze pressure (>124 mmHg); Group 2 (cortical apraxia, i.e., poor cortical activation)-normal cough EMG, low squeeze EMG, and low anal squeeze pressure; Group 3 (muscle damage)-normal cough EMG, normal squeeze EMG, and low anal squeeze pressure; and Group 4 (pudendal nerve damage)-low cough EMG, low squeeze EMG, and low anal squeeze pressure. The four patient groups were not different with regards to the patient's age, BMI, parity, and FISI scores. 3D ultrasound images of the anal sphincter complex revealed significant damage to the internal anal sphincter, external anal sphincter, and puborectalis muscles in all four groups. The FI patients are a heterogeneous group; majority of these patients have significant damage to the muscles of the anal sphincter complex. Whether biofeedback therapy response is different among different patient groups requires study.

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 ...

P82 Pelvic neurophysiological and urodynamics findings in patients with sacral-level tarlov cysts

ObjectivesSacral Tarlov cysts (TC) are frequent incidental findings on spinal MRI. Controversy remains regarding their ability to cause nerve root compression. Pelvic neurophysiological and urodynamics testing provides information about sacral nerve root involvement.DesignCase seriesSubjectsPatients with MRI evidence of sacral (S1, 2 or 3) TC seen in the Uro-neurology Department between 2011 and 2018.MethodsClinical, neurophysiological and urodynamics data were reviewed.Results13 patients (9 females, mean age54/SD13.1) were included. Symptoms were urgency/incontinence (n=8), hesitancy/urinary retention (n=7), bowel complaints (n=4), sexual complaints (n=3), back pain (n=5), genital/pelvic pain (n=6), genital numbness (n=5), impaired sensation of bladder fullness (n=2), lower limb (LL) pain/hypoesthesia (n=6), LL weakness (n=2). The following neurophysiological abnormalities were seen: anal sphincter EMG (n=10) evidence for reinnervation (n=8), pudendal sensory evoked potentials (SEPs) (n=6) absent response (n=1), S2 and S3 dermatomal SEPs (n=6) absent response (n=2), sympathetic skin response (n=6) absent response (n=3). Findings in cystometry (n=5) were: detrusor underactivity (n=2), detrusor after-contraction (n=1), equivocal obstructed voiding (n=1) and reduced bladder compliance (n=1).ConclusionsAbnormal results in urodynamics and pelvic neurophysiology suggest involvement of the somatic and autonomic sacral innervation. Further studies are required to explore any association between structural changes on MRI and functional changes in urodynamics and neurophysiology.

993 - Wireless Anal Sphincter EMG Recording to Assess Dyssynergic Defecation: The Effects of Posture and Privacy

993 - Wireless Anal Sphincter EMG Recording to Assess Dyssynergic Defecation: The Effects of Posture and Privacy

Incontinence - Etiology, diagnostics and Therapy

Fecal incontinence is defined by the unintentional loss of solid or liquid stool, and anal incontinence includes leakage of gas and / or fecal incontinence. Anal-fecal incontinence is not a diagnosis but a symptom. Many patients hide the problem from their families, friends, and even their doctors. Epidemiologic studies indicate a prevalence between 7-15 %, up to 30 % in hospitals and up to 70 % in longterm care settings. Anal-fecal incontinence causes a significant socio-economic burden. There is no widely accepted approach for classifying anal-fecal incontinence available. Anal-fecal continence is maintained by anatomical factors, rectoanal sensation, and rectal compliance. The diagnostic approach comprises muscle and nerve injuries by iatrogenic, obstetric or surgical trauma, descending pelvic floor or associated diseases. A basic diagnostic workup is sufficient to characterize the different manifestations of fecal incontinence in most of the cases. This includes patient history with a daily stool protocol and digital rectal investigation. Additional investigations may include anorectal manometry, anal sphincter EMG, conduction velocity of the pudendal nerve, needle EMG, barostat investigation, defecography and the dynamic MRI. Therapeutic interventions are focused on the individual symptoms and should be provided in close cooperation with gastroenterologists, surgeons, gynecologists, urologists, physiotherapeutics and psychologists (nutritional-training, food fibre content, pharmacological treatment of diarrhea/constipation, toilet training, pelvic floor gymnastic, anal sphincter training, biofeedback). Surgical therapy includes the STARR operation for rectoanal prolapse and sacral nerve stimulation for chronic constipation and anal-fecal incontinence. Surgery should not be applied unless the diagnostic work-up is complete and all conservative treatment options failed.

Detecting Urinary Bladder Contractions: Methods and Devices

In patients suffering from neurogenic detrusor overactivity, continence can be regained by conditional stimulation of the dorsal genital nerve (DGN); that is applying electrical stimulation to the DGN at the onset of an involuntary contraction. For this scheme to work, a sensor capable of reliably detecting the onset of bladder contractions is needed. This article reviews the methods proposed for or associated with detection of bladder contractions, and their applicability to onset detection is assessed. Fourteen methods are described in this review; bladder pressure, urethral sphincter EMG and anal sphincter EMG are the most promising options for onset detection. For all three modalities, however, further research is needed before clinical application becomes viable.

Utility of sphincter electromyography and sacral reflex studies in women with cauda equina lesions

Sacral neurophysiologic studies have demonstrated their utility in men with suspected neurogenic sacral dysfunction. However, no similar studies have been performed in women. The present study aimed to test the utility of sacral neurophysiologic assessment in women with chronic cauda equina lesions. Twenty-four women with clinical and radiological signs supportive of chronic cauda equina lesions, and a group of 60 control women without clinical symptoms or signs of sacral neuropathic lesion were included. Clinical examination, including testing of saddle sensation, and neurophysiologic testing, including quantitative anal sphincter EMG and clitoro-cavernosus reflex testing (on single and double electrical, and mechanical stimulation), were performed on each side separately. Sensitivity, specificity, positive predictive value, and negative predictive value were calculated. Respective sensitivities, specificities, positive predictive values, and negative predictive values were 63%, 92%, 83%, and 86% for quantitative anal sphincter EMG, 92-96%, 67-80%, 52-59%, and 95-96% for neurophysiologic testing of the clitoro-cavernosus reflex (using different stimulation techniques), and 96-100%, 62-75%, 50-55%, and 97-98% for their combinations. This study complements previous reports in men supporting the clinical utility of an neurophysiologic protocol that includes both quantitative anal sphincter EMG and sacral reflex studies for assessment of patients with suspected peripheral sacral lesions. Very high sensitivity and negative predictive value confirm high utility of sacral neurophysiologic studies in confirmation and exclusion of sacral neuropathic lesion.

Modulation of the human cortico-anal brain gut axis with lumbosacral non-invasive magnetic stimulation

IntroductionFunctional gut and defecation disorders are common yet difficult to manage and brain-gut axis dysfunction has been implicated in both. A better mechanistic understanding is of importance in designing new...

Diagnostik bei anorektalen Erkrankungen

Anorectal disorders which often lead to fecal incontinence are a frequent problem especially in elderly patients. Direct risk factors for fecal incontinence are higher age, female sex and co-morbidity with reduced health status. Anorectal disorders cause significant socio-economic burden. Impairment of the structural and functional integrity of the anorectum are mostly multifactorial (integrity of the muscles, sensory function, stool consistency) leading to depression and fear with reduction in quality of life. A basic diagnostic work up is sufficient to characterize the different manifestations of anorectal disorders in most of the cases. This includes patient history with daily stool protocol, clinical and endoscopic investigation. Follow-up investigations include anorectal manometry, anal sphincter-EMG, conduction velocity of the pudendal nerve, needle-EMG, barostat investigation, defecography and the dynamic MRT. Therapeutic interventions are focussed on the individual symptoms and should be provided in close cooperation with gastroenterologists, surgeons, gynecologists, urologists, physiotherapeutics and psychologists (nutritional-training, food fibre content, pharmacological treatment of diarrhea/constipation, toilet-training, pelvic floor-gymnastic, anal sphincter training, biofeedback). Indication for surgical therapy is rarely seen and should be decided only after complete diagnostic work-up and only when all conservative treatment options have failed. Surgical treatment should be provided only in experienced clinical centres.

Erectile and urinary dysfunction may be the presenting features in patients with multiple system atrophy: a retrospective study.

Multiple system atrophy (MSA) is a progressive neurodegenerative disease characterized by parkinsonism and cerebellar, autonomic, urinary, and/or pyramidal dysfunction. Urinary and erectile dysfunction (ED) symptoms are prominent early features in men with MSA. Autonomic failure, considered until recently to be the cause of ED in these men, is commonly expressed through symptoms of orthostatic hypotension (OH). The aim of this retrospective study is to examine the chronological relationship between the development of urogenital symptoms and those of OH in patients diagnosed with MSA and discuss its significance in the aetiology of ED in these patients. A total of 71 male patients, referred to a Uro-Neurology department with a diagnosis of 'probable MSA', were reviewed in terms of 'autonomic' symptoms only--OH and lower urinary tract symptoms, accompanied by ED--present at the time of their referral. Laboratory investigations including anal sphincter EMG and/or autonomic function tests (AFTs) were performed in 75 and 90% of the patients, respectively. At presentation, urinary complaints were recorded in 96% of patients and ED in all patients that this was inquired about. The onset of ED had preceded the onset of bladder symptoms in 58% and the onset of OH symptoms in 91% of these men. Bladder symptoms also preceded symptoms of OH in 76% of patients. Sphincter EMG was abnormal in 91% and AFTs in 77% of the patients tested. Almost all patients with abnormal EMG had troublesome urinary symptoms. AFTs showed similar sensitivity relating to symptoms. At presentation, urogenital symptoms are common in patients with probable MSA and are often not accompanied by symptoms of OH. The earlier occurrence of ED in men with MSA suggests a lack of a causal relationship to hypotension. The notion that MSA possibly affects the dopaminergic mechanism of erectile function is discussed.

Quantitative anal sphincter EMG in multisystem atrophy and 100 controls

OBJECTIVETo evaluate data of quantitative anal sphincter EMG in normal controls and to compare them with patients with multiple system atrophy (MSA).METHODSQuantitative anal sphincter EMG were performed on 100 normal...

Standardisation of anal sphincter EMG: high and low threshold motor units

Objective: The anal sphincter muscle has a proportion of low threshold motor units (MUs) that are continuously active and other, recruitable high threshold MUs. In standard EMG recordings, motor unit potentials (MUPs) of the later seem to be of higher amplitudes. A quantitative EMG study was performed to assess possible consequences of sampling MUPs at different levels of sphincter activation.Methods: Fifteen females without uroneurological disorders were studied. After insertion, standard concentric EMG needle was left in the anal sphincter muscle undisturbed for 1 min; then 30 s of the remaining continuous, and 1 min of voluntarily increased EMG activity were recorded on a DAT recorder. MUPs were collected and analysed by ‘Multi-MUP’ analysis. MUPs analysed during relaxation constituted the ‘low threshold MUP pool’. MUPs sampled on activation were checked for those, already sampled during relaxation, (which were discarded), and the remaining MUPs constituted the ‘high threshold MUP pool’. Parameters of both MUP pools were compared.Results: High threshold MUPs were found to be significantly larger than low threshold MUPs.Conclusions: EMG investigator should be aware of the differences of MUPs sampled at various anal sphincter activity levels. For the technique of ‘Multi-MUP’ analysis sampling at an activity level which provides 3–5 MUPs per detection site would seem practical, providing a standardised approach suitable for comparing normative data with individual findings from most patients.

Role of rectosigmoid junction in fecal continence: an experimental study.

To investigate the reason why, during a mass contraction, the stool moving from the colon to the sigmoid colon stops short of the rectosigmoid junction (RSJ) instead of passing directly to the rectum, and whether the sigmoid colon and RSJ share in the anorectal continent mechanism, 12 mongrel dogs were studied. Under anesthesia, the anorectum was excised, sigmoid colon and RSJ were mobilized and the caudal end was anastomosed to the perianal skin within the external anal sphincter. The pressures in the sigmoid colon, RSJ, rectum and rectal neck were measured before anorectal excision. After excision, the pressure was registered in the neorectum (sigmoid colon) and the RSJ. The external anal sphincter EMG was recorded and the balloon expulsion test performed before and after anorectal excision and after anesthetization of the neorectum. Balloon distension of the sigmoid colon to a mean volume of 46.6+/-7. 6 ml raised the pressure in the sigmoid colon (p<0.001) and decreased it in the RSJ (p<0.05) and the balloon was dispelled to the rectum; no change occurred in the external anal sphincter EMG activity. Neorectal balloon distension to a mean volume of 62.3 +/- 8.2 ml effected a pressure rise in the neorectum (p<0.001) and a momentary increase in the external anal sphincter EMG activity, followed by a decrease of the RSJ pressure (p<0.05); the balloon was dispelled to the exterior. Balloon distension of the anesthetized neorectum effected no significant changes in neorectum and RSJ pressures or external anal sphincter EMG activity. In conclusion, it is assumed that the stools arriving from the colon are halted at the RSJ by the existing high-pressure-zone and the presence of a potential sphincter at the RSJ. We suggest that fecal continence occurs at 2 levels: an involuntary one at the RSJ and a voluntary one at the rectal neck.

Anorectal functions in patients with spinal cord injury.

We wished to establish anorectal functions in patients with spinal cord lesions, related to the level of lesion and its completeness. We also wished to determine the value of neurophysiological tests for completeness of transsections in comparison with manometry and visceral sensory testing. In 32 patients (31.5 +/- 14.1 years, 25 males) with spinal trauma, completeness of transsection was assessed clinically. In 16 of these patients (30 +/- 15.6 years, nine males), a neurological work-up included recording of somatosensory evoked potentials (SEP) and motor evoked potentials (MEP) from the pudendal nerve within the first week after trauma. Also, anal sphincter EMG and pudendal nerve terminal motor latency (PNTML) were assessed. All patients also underwent conventional anorectal manometry and visceral sensory testing. Of all 32 patients, 15 were judged as 'complete' based on their clinical signs. Of those 16 tested neurologically, seven were labelled 'complete' since no MEP or SEP were detectable; one had pudendal SEP and MEP present, while SEP were present but delayed (47.0 +/- 8.8 msec) in the remaining patients. In four of these patients, also MEP were recorded (27.9 +/- 5.2 msec) and normal. PNTML was present in 12/16 patients independent of the completeness of lesion, and was rated normal in nine and delayed in three patients. EMG was normal in five, and pathological in 11 cases. In 5/15 cases of those judged as 'complete' (in 3/7 evaluated neurologically), visceral sensory testing revealed a minimal threshold for rectal perception of distension of 44 mL (range: 10-130), which sometimes was also perceived as urge to defecate. In a further case, manometry showed major voluntary action of the anal sphincter. These patients had lesions at all levels of the spinal column, ranging from cervical (C4,C6,C7) via thoratical (2 x T7,T8,T12) to lumbar segments. Anorectal function testing, and specifically visceral sensory testing may be superior to neurological assessment of 'completeness' of spinal cord lesions. It may be that visceral afferent pathways others than spinothalamic tract are involved in rectal perception that are less accessible to conventional neurophysiological diagnostic work-up.

Inferior Rectal Nerve Stimulation for Anal Sphincteric Control: Experimental Study

The effect of inferior rectal nerve (IRN) stimulation on sphincteric control of the rectal neck was studied in eight dogs. With the dog under anesthesia, the IRN was exposed through para-anal incision, and a bipolar electrode was applied to it. Response of the rectal and rectal neck pressures as well as external anal sphincter (EAS) EMG activity to IRN stimulation was determined. IRN stimulation resulted in increase in both the rectal neck pressure ( P < 0.01) and the EMG activity of EAS ( P < 0.01). Response increased with increasing stimulation frequency up to 50 Hz, above which no more response occurred. Rectal pressure showed no change ( P > 0.05). Both the latency and the duration of response decreased with increased stimulation. The response was resumed after an off-time of twice the stimulation phase. Long-term activation has not been associated with an impairment of nerve responsiveness or with electrode migration or break. To conclude, a stimulus of 50 Hz evokes the most adequate EAS contraction and RN pressure elevation. Chronic electrostimulation of the perineal nerve may restore EAS tone.

Multisystematrophie

Multiple system atrophy (MSA) is an adult-onset sporadic degenerative disease of the CNS that can cause parkinsonism, autonomic failure, cerebellar and pyramidal signs in any combination. Often, the diagnosis of clinically probable MSA can be made without the need for additional investigations, MSA of SND or OPCA type being diagnosed according to whether parkinsonism or cerebellar signs predominate. However, in other patients a pathological anal or urethral sphincter EMG may enable the diagnosis to be established. The cerebral pathology of this condition comprises cell loss and gliosis in the nigrostriatal and/or olivopontocerebellar systems. In addition there is loss of sympathetic neurons of the intermediolateral cell columns, and of anterior horn cells from Onuf's nucleus, in the spinal cord. Oligodendroglial intracytoplasmic inclusions are found in many brain areas in all cases of MSA.

Electromyography of the internal anal sphincter performed under endosonographic guidance description of a new method

The aim of our study was to investigate internal anal sphincter electromyographic signals. Electromyography of the internal anal sphincter was performed with platinum wire electrodes in six healthy volunteers (three males and three females), inserted under endosonographic guidance. Platinum wire electrodes were also inserted into the external anal sphincter. Activity of both the internal and external and sphincter in a 40-second period was measured. Internal anal sphincter median activity was 22.1 (range, 5.5-67.6) microV. Slow-wave activity was 47 cycles/minute (range, 34-55 cycles/minute). After inflation of a rectal balloon with air until a constant relaxation of the anal canal was obtained, a decrease in internal and sphincter activity to 15.9 (1.2-31.3) microV as well as a decrease in slow-wave activity to 34 cycles/minute (range, 27-40 cycles/minute) was found. The original internal anal sphincter EMG was resumed after deflation of the rectal balloon. External anal sphincter median activity was 3.1 (range, 0.77-18.6) microV. During inflation of the rectal balloon, a reflex increase in external sphincter EMG activity was found. With the rectal balloon fully inflated a part of this increase was still present, 11.0 (1.9-24.6) microV. In some of the subjects, this increased activity was superimposed on the internal anal sphincter recordings as well. During a voluntary squeeze it was not possible to identify internal anal sphincter activity due to activity of the external anal sphincter totally overriding the internal anal sphincter signal. Precise EMG recordings from the internal anal sphincter is possible with endosonographic guidance of the electrodes, except during voluntary squeezing of the external and sphincter.

Anorectal tightening reflex: role in fecal incontinence.

The present study describes the clinical significance of the anorectal tightening reflex (ATR) in normal and incontinent subjects. It was examined in 16 healthy volunteers and 11 subjects incontinent to flatus and fluid stools; 5 of the latter had in addition fecal soiling. The rectum was distended by a condom inflated with carbon dioxide, while the rectal and rectal neck (RN) (anal canal) pressures were measured, and the external (EAS) and internal anal sphincter (IAS) EMG activity was recorded. The rectum was inflated at two rates: slow and rapid. In normal subjects, the RN pressure increased upon slow rectal inflation; the IAS EMG was augmented. Pudendal nerve block and phentolamine administration revealed that this pressure increase is due to increased IAS tone which tightens the RN against the slow rectal filling by the time adaptive reaction occurs. Rapid rectal filling evoked Gower's rectoinhibitory reflex. Thus, while increased IAS tone in the ATR protects against involuntary incontinence upon 'slow' rectal filling, the increased EAS tone of Gower's reflex protects in the case of 'rapid' filling. Of the 11 incontinent patients, the 5 with fecal soiling did not show ATR, and investigative results pointed to the IAS as being responsible for incontinence. The other 6 patients had normal ATR but nonresponsive EAS on rapid filling. Findings suggest that the ATR plays a role in maintaining continence during slow rectal distension and that a disordered ATR due to IAS dysfunction leads to fecal incontinence. Thus ATR may be useful as an investigative tool in anorectal disorders.

The importance of the orientation of the electrode plates in recording the external anal sphincter EMG by non-invasive anal plug electrodes

Two non-invasive anal plug electrodes of similar size have been compared, one with the electrode plates orientated circularly in the anal canal and the other with the plates in the long axis of the anal canal. There was a significant increase in the amplitude in the EMG signals recorded at rest and during squeeze from the external anal sphincter with a longitudinally placed electrode in 117 patients. Inappropriate contraction of the external anal sphincter when straining at stool was more readily detected using the longitudinal electrode in 52 patients investigated for intractable constipation. The longitudinal electrode detected the amplitude of the response to the elicitation of a pudeno-anal reflex more readily than the circular electrode. When in 12 of the 117 the pudeno-anal reflex EMG signal was either absent or not detected with the circumferential plug electrode, the longitudinal electrode detected the presence of a low amplitude response in 11 of these. When the non-invasive longitudinal electrode was compared to invasive fine wire stainless steel electrodes, a correlation was found for external anal sphincter resting EMG (r = 0.99, p less than 0.01), voluntary squeeze EMG (r = 0.99, p less than 0.001) and strain EMG (r = 0.91, p less than 0.01). The longitudinal anal plug electrode thus facilitates surface acquisition of EMG activity.

Anorectal function in the solitary rectal ulcer syndrome.

The anorectal function of nine patients with solitary rectal ulcer syndrome (SRUS) (5 F: 4 M, median age, 27 (range, 19-41 years) and nine control subjects (5 F: 4 M, median age, 47 (35-66) P less than 0.01) has been investigated by a new technique that radiologically visualizes the anorectum during voiding of a semisolid contrast medium, while simultaneously measuring intrarectal pressure and anal sphincter EMG activity. A degree of rectal prolapse was demonstrated in eight of the SRUS patients; six of these lesions were clinically occult. Abnormal failure of the anal sphincter to relax on voiding was present in seven of the SRUS patients. These abnormalities resulted in the SRUS patients requiring a greater increase in intrarectal pressure (median, 100 cm water) to void than the control subjects (median, 65 cm water, P less than 0.01). This combination of high intrarectal pressure and rectal prolapse during staining seems to be the cause of SRUS.