Botulinum toxin in the treatment of chronic urinary retention in women.

Six women were identified as having difficulty in voiding or complete urinary retention due to abnormal myotonic-like electromyographic (EMG) activity in the striated muscle of the urethral sphincter. An attempt was made to improve voiding by injection of botulinum toxin into the striated sphincter muscle. Although 3 patients then developed transient stress incontinence, demonstrating that sufficient botulinum toxin had been given to cause sphincter weakness, no patient had significant symptomatic benefit.     

Disposable vaginal surface electrode for urethral sphincter electromyography

During the last 2 years we have developed a disposable vaginal surface electrode for electromyographic (EMG) recording from the urethral striated sphincter. We describe the design of the electrode and report the results of laboratory testing, including directional selectivity of the electrode, electrode impedance, testing for movement artefacts and stability of position. Clinical studies which included 138 cystometries with sphincter EMG, 133 pressure-flow EMG studies and four urethral pressure profile studies with sphincter EMG, demonstrated that the electrode gave technically good and reliable electromyographic data. The registration caused no discomfort to the patient and did not disturb the act of micturition. We recommend this technique for the evaluation of urethral striated muscle activity during urodynamic studies in women, since it is simple, inexpensive and reliable.     

Concentric needle electrodes are superior to perineal surface-patch electrodes for electromyographic documentation of urethral sphincter relaxation during voiding

OBJECTIVE: To compare interpretations of electromyographic (EMG) recordings from perineal surface patch electrodes (PSPEs) to those from urethral concentric needle electrodes (CNEs) during voiding. PATIENTS AND METHODS: Consenting women underwent urodynamic testing with a 30 G, 3.8 cm CNE at the 12 o'clock position in the striated urethral sphincter muscle, and with PSPEs placed at the 2 and 10 o'clock positions around the anus. Pressure-flow studies were conducted with simultaneous input from both EMG electrodes. Representative, de-identified paper copies of EMG signals were assembled by chronology and electrode type. Six examiners unaware of the patient details were asked to determine if the tracings were interpretable and whether there was quiescence of the urethral sphincter motor unit during voiding. The agreement between the interpretations of each tracing was assessed using McNemar and kappa statistics. RESULTS: Twenty-two women undergoing urodynamic testing for incontinence (16), voiding dysfunction (two) or urinary retention (four) participated in this study. CNE tracings were consistently more interpretable than PSPE tracings (mean 89% vs 67%). When tracings were interpretable, a significantly higher percentage of CNE EMG tracings (mean 79%) had urethral sphincter motor unit quiescence than PSPE EMG tracings (mean 28%). The kappa values for agreement among the reviewers' interpretations were highly variable and none were statistically significant. Reviewers unanimously agreed on only 12 of the 44 tracings, and 11 of these showed quiescence when using a CNE. CONCLUSIONS: CNEs are more often interpretable than PSPEs for determining motor unit quiescence during voiding. CNE EMG appears to have greater clinical utility for central reading than PSPEs.     

The etiology of urinary retention after surgery for genuine stress incontinence

Transient postoperative urinary retention after stress incontinence surgery is common, and there is no widely accepted method of hastening the return to normal voiding. The etiology of this retention is poorly understood. Failure of the relaxation of the striated external urethral sphincter has been proposed as an etiologic agent, but has not been documented. Ten patients about to undergo a Burch colposuspension or sub-urethral sling, who demonstrated normal preoperative voiding, were recruited to a study of postoperative retention. Hook-wire electromyographic (EMG)probes were placed into the external urethral sphincter while the patients were under anesthesia, and a suprapubic catheter was placed. We performed instrumented voiding trials 1 or 2 days after surgery while continuously recording urethral EMG and intravesical pressure. Two patients demonstrated normal voiding. Two patients were able to void but demonstrated no EMG silencing. Six patients were unable to void and demonstrated persistent EMG activity. Four of these demonstrated no detrusor contraction, whereas two demonstrated detrusor contractions. All patients resumed normal voiding by clinical parameters within 14 days of surgery. Our study supports other research that suggests that failure of relaxation of the striated urethral sphincter contributes to postoperative urinary retention.     

Control and coordination of bladder and urethral function in the brainstem of the cat

Stimulation and lesion experiments in the pontine tegmentum of 34 cats, with urodynamic measurements both pre- and peroperatively and during up to 4 months of follow-up, have confirmed the existence of two different brainstem regions concerned with lower urinary tract function. In the dorsolateral pontine tegmentum, a compact, dorsomediolaterally located M region, corresponding to Barrington's micturition centre, reacts specifically to electrical stimulation, causing prompt relaxation of the anal and urethral striated sphincters followed after about 2 s by detrusor contraction, as in normal micturition. Bilateral lesions in this M region lead to a 2–9 week period of urinary retention, during which detrusor activity is depressed and the bladder capacity increases. Stimulation in a larger, more diffuse, more laterally located L region elicits sphincter activity: contraction of the striated urethral sphincter together with an increase in the anal-sphincter EMG, or relaxation of the striated urethral sphincter together with either a decrease or an increase in the anal-sphincter EMG. Provided lethal respiratory complications can be avoided, bilateral lesions in this L region lead after a few days to a state, lasting up to 2 months, in which there is urinary incontinence accompanied by a decrease in the bladder capacity and detrusor overactivity. Neither type of lesion leads to true detrusor-urethra dyssynergia. However, because the amplitude of anal-sphincter EMG sometimes increases when the striated urethral sphincter relaxes, observations of the anal-sphincter EMG can misleadingly suggest dyssynergia. Brainstem mapping of the results of stimulation suggests a motor pathway running from the M to the L region and another descending caudally from the L region. The observations suggest that the M region forms a true micturition centre, facilitating the detrusor voiding contraction and also (via the presumptive connection with the L region) ensuring synergic sphincter relaxation. The L region appears not only to relay this voiding sphincter relaxation, but to be responsible for control of the pelvic floor and its sphincters in general, and for helping to maintain urinary continence.     

Urethral pressure variations in women with neurourological symptoms: I. Relationship to urethral and pelvic floor striated muscle

Simultaneous urethrocystometry and electromyography (EMG) of the urethral and pelvic floor striated muscle were performed in 42 gynecological patients with neurourological symptoms. Their maximum urethral pressure varied between 20 and 124 cm H₂O. A correlation analysis was performed between the maximum urethral pressure and the integrated EMG of the urethral striated muscle and the pelvic floor striated muscle. The analyses were performed on results obtained in 1-min periods during bladder filling before first desire to void was reported, when first desire to void was reported, and when a strong desire to void was reported. In 21 patients no correlation was found between the urethral and pelvic floor striated muscle activity and the maximum urethral pressure at any stage of bladder filling. In the other 21 patients a correlation was found in at least 1 of the 3 stages. At all stages of bladder filling a correlation was found significantly more often between the maximum urethral pressure and the striated urethral muscle EMG than between the maximum urethral pressure and the striated pelvic floor muscle EMG. Thus, activity of the urethral striated muscle cannot be reliably studied in an EMG recording from the pelvic floor striated muscle. In the same patient, periods with a correlation could be succeeded by periods without a correlation. Thus, the urethral pressure variations may in the same patient sometimes be caused mainly by the urethral striated muscle and sometimes mainly by the urethral smooth muscle.     

A comparative study of various electrodes in electromyography of the striated urethral and anal sphincter in children

The series comprised 41 children aged 6 to 14 years consecutively referred with recurrent urinary tract infection and/or enuresis. Carbon dioxide cystometry was carried out in the supine and the erect position and combined with simultaneous electromyography (EMG). The external urethral sphincter was examined with a ring electrode mounted on a urethral catheter, while recordings from the striated anal sphincter were based on an anal plug electrode and perianal electrocardiographic (ECG) skin electrodes: 211 EMG and cystometric examinations were performed and all three methods gave satisfactory results. Correlation between them was good, as was reproducibility. Perianal surface ECG electrodes are recommended for the evaluation of functional disturbances of the external sphincter. They are painless, easy to use, and are well tolerated by the patient.     

Urethral pressure variations in women with neurourological symptoms: III. Relationship to urethral wall venous plexus

Twenty-five women were investigated in order to find out if the urethral submucous venous plexus may influence urethral pressure variations. Urethral and bladder pressure were measured with a microtip transducer catheter. Electromyography (EMG) and integrated EMG from the urethral striated muscle were recorded using a concentric needle electrode. Blood volume in the urethral submucous venous plexus was measured with a urethral photopletysmograph probe. In 9 women without neurourological symptoms, during squeezing there was increased urethral striated muscle activity, increased urethral pressure and decreased blood volume. When they were asked to void the opposite was found. In 16 patients with marked urethral pressure variations a negative correlation was found between the maximum urethral pressure and the photopletysmograph tracing. In 7 of 8 patients a negative correlation was found also between the integrated EMG tracing and the photopletysmograph tracing, but a positive correlation was found between the maximum urethral pressure and the EMG of the urethral striated muscle. In 1 of the 8 patients no correlation was found between EMG activity and maximum urethral pressure and between EMG activity and the photopletysmograph tracing. The results demonstrate that the urethral venous plexus becomes emptied secondary to contractions of the urethral striated and/or smooth muscle and filled with blood secondary to relaxation of the same muscles. Hence, the urethral venous plexus does not influence the urethral pressure actively.     

Electromyographic study of the striated urethral sphincter in type 3 stress incontinence: evidence of myogenic-dominant damages

Objectives. To determine the electromyographic features of the striated urethral sphincter in patients with type 3 stress incontinence (SI) due to intrinsic sphincteric deficiency (ISD).Methods. We performed electromyography (EMG) of the striated urethral sphincter muscle and urodynamic studies in a total of 51 women, 41 female patients with type 3 SI and 10 women with normal urinary control (NUC). The results were analyzed in both groups, and the correlation of EMG findings with the patient characteristics and urodynamic parameters was evaluated.Results. Motor unit potentials (MUP) of SI patients showed significantly shorter duration (P = 0.0014), lower amplitude (P = 0.0008), and larger number of phases (P = 0.0022) compared with those in the NUC group. Thirty (73%) of the SI patients showed an obvious low amplitude (less than 350 μV)/short duration (less than 4.5 milliseconds)/polyphasic pattern and early recruitment of interference activity with low amplitude at voluntary contraction of the striated sphincter, both indicating existence of myogenic damages. These patients showing myogenic damages had significantly lower Valsalva leak point pressure (P = 0.002) and more leakage in the pad-weigh test (P = 0.010) compared with the SI patients without myogenic damage findings.Conclusions. These results suggested that myogenic-dominant damages of the striated urethral sphincter may contribute to the etiology of ISD in most patients with type 3 SI.     

Electromyography of the female urethral sphincter

Electromyography of the urethral striated sphincter gives information on the function of this muscle which consists of two structures: the intraurethral and periurethral sphincter. The types of electrode used to perform EMG of this sphincter are reviewed. The EMG findings of the peri- and intraurethral sphincters with empty bladder at rest and during maximal voluntary contraction are given as well as during bladder filling. Assessment of the urethral sphincter is described in different pathological situations. Methods and results of evoked potentials and nerve conduction measurements are also described in normal and pathological conditions.     

Maximum urethral closure pressure and sphincter volume in women with urinary retention

PURPOSE: In 1988 a syndrome of isolated urinary retention in young women that is associated with electromyographic abnormality of the striated urethral sphincter was described. It was hypothesised that urinary retention resulted from a failure of sphincter relaxation. The electromyographic abnormality causes overactivity of the muscle and may induce changes of work hypertrophy. If the hypothesis that the electromyographic abnormality is the cause of urinary retention is correct, we would expect the urethral sphincter to be enlarged and the urethral pressure profile to be increased in these women. We evaluated the role of static urethral pressure profilometry and transvaginal ultrasound in women in urinary retention. MATERIALS AND METHODS: A total of 66 women in complete or partial urinary retention underwent electromyography of the striated urethral sphincter using a concentric needle electrode, followed by urethral pressure profile and/or urethral sphincter volume measurement by transvaginal ultrasound. RESULTS: Maximum urethral closure pressure plus or minus standard deviation was significantly increased in patients with versus without the electromyographic abnormality (103 +/- 26.4 versus 76.7 +/- 18.4 cm. water, p <0.001). Maximum urethral sphincter volume was also increased in women with versus without the abnormality (2.29 +/- 0.64 versus 1.62 +/- 0.32 cm.3, p <0.001). CONCLUSIONS: The results of this study are consistent with the hypothesis that a local sphincter abnormality is the cause of urinary retention in a subgroup of women. Urethral pressure profilometry and sphincter volume measurement are useful for assessing these cases, especially when sphincter electromyography is not readily available.     

Effect of cerebellectomy on reflex micturition in the decerebrate dog as determined by urodynamic evaluation

The effect of cerebellectomy on reflex micturition in the decerebrate dog was investigated by cystometric and striated urethral sphincter EMG studies. Before and after cerebellectomy, reflex micturition consisting of bladder contraction and spasmodic contraction of the striated urethral sphincter occurred when a critical degree of filling was reached. Cerebellectomy showed no influence on the striated urethral sphincter EMG activity. However, cerebellectomy produced a significant decrease in threshold volume and threshold pressure during the collecting phase, and also in the contraction pressure and voided volume of the emptying phase. The present study suggests that the cerebellum plays an inhibitory role in the collecting phase and a facilitatory role in the emptying phase during the entire reflex micturition cycle of the decerebrate dog. Further study will have to be done concerning the neurotransmission mechanism that causes these different effects in the collecting and emptying phases.     

Modification of urge incontinence by biofeedback mechanisms

Urge incontinence caused by hyperactive urethral closing mechanism can be influenced by relaxation training of the striated sphincter muscle. This is done through a biofeedback mechanism with pelvic floor EMG control. The indications are for urge incontinence with urethral hyperactivity and pelvic floor hyper-reactivity diagnosed through urodynamic examination. Twenty-two female patients with urge incontinence were treated for four weeks by biofeedback training with a portable pelvic floor EMG apparatus. The urge incontinence were improved subjectively and objectively in 73%. The therapy focused on the striated muscle seemed to have better results than therapy of the detrusor.     

Electromyographic abnormalities in the urethral and anal sphincters of women with idiopathic retention of urine.

Previous concentric needle studies of the urethral sphincter in women with idiopathic urinary retention have found evidence of denervation and reinnervation as well as abnormal patterns of muscle fibre discharge--complex repetitive discharges (CRDs). In order to test the hypothesis that these abnormalities represented a more widespread disease process of pelvic floor function, we carried out an electromyographic (EMG) study of both anal and urethral sphincters in 18 women with idiopathic urinary retention. The urethral sphincter EMG was abnormal in 15 patients. These abnormalities included polyphasic and long duration potentials. Complex repetitive discharges were identified in 8 women. However, abnormalities of the anal sphincter were found in 14 of the 15 patients with abnormal urethral sphincter EMGs, polyphasic and abnormally long duration potentials being found in the anal sphincters of all 14 patients. In addition, 7 of the 8 women who had complex repetitive discharges in the urethral sphincters had similar complex repetitive discharges in their anal sphincters. Women with complex repetitive discharges had a significantly greater proportion of abnormal potentials than women with no such repetitive discharges. These results support the previous findings of electromyographic urethral sphincter abnormalities in women with idiopathic urinary retention, but also suggest that these abnormalities reflect a widespread disease process involving the pelvic floor in such patients.     

Urinary retention in women: its causes and management

OBJECTIVE: To report the experience of the last 4 years from a centre to which women with voiding difficulties and urinary retention were referred nationally, describing what investigations were helpful in making a diagnosis and the management strategies used. PATIENTS AND METHODS: Women with voiding difficulties and urinary retention remain a diagnostic and management challenge, and those with no anatomical or neurological basis for their symptoms may be dismissed, assuming that their retention has a psychogenic basis. The finding of an electromyographic (EMG) abnormality of the striated urethral sphincter explaining their disorder (Fowler's syndrome) has led to the referral of women for consideration of that diagnosis. Thus we audited the referrals to the centre over a 4-year period of such women. RESULTS: In all, 247 women (mean age 35 years) with complete (42%) or partial retention (58%) were referred; 175 (71%) had urethral pressure profilometry, 141 (57%) had a transvaginal ultrasonographic measurement of the sphincter volume, and 95 (39%) had sphincter EMG. The mean maximum urethral closure pressure difference between patients with an EMG abnormality (101.5 cmH(2)O) and the patients with known other causes of voiding dysfunction (66.2 cmH(2)O) was 35.3 cmH(2)O (P < 0.05). In patients with complete retention there was a significant difference in sphincter volume between those who were EMG-positive (2.14 mL) or EMG-negative (1.64 mL) (P < 0.05). CONCLUSION: These investigations helped to classify the cause of retention in two-thirds of cases. The commonest diagnosis was Fowler's syndrome, in which sacral nerve stimulation is the only intervention that restores voiding.     

Urethral function in neurological disorders of the lower urinary tract

Simultaneous measurements of intravesical pressure, urethral pressure, and electromyographic activity of perianal muscles were performed during bladder filling and voiding in 56 patients with neurogenic lower urinary tract dysfunction. In 21 patients simultaneous measurements were taken of the EMG activity of the striated-muscle external urethral sphincter. During bladder filling the urethral pressure was found to correspond to the EMG activity of both muscles only in those patients with normal urethral pressure. During voiding the EMG activity of neither muscle corresponded well with changes in urethral pressure. The EMG activity of perianal muscles corresponded to the activity of the external urethral sphincter during filling of the bladder but not during voiding.     

Clinical, Hormonal and Pathological Findings in a Comparative Study of Adrenocortical Neoplasms in Childhood and Adulthood

The present study investigated the role of nitric oxide (NO) in the reflex changes in urethral outlet activity during micturition. Isovolumetric bladder contractions, urethral pressure and external urethral sphincter electromyogram (EUS EMG) activity were recorded independently in urethane-anesthetized rats. During reflex bladder contractions, the urethra exhibited reflex responses characterized by an initial decrease in urethral pressure in conjunction with a rise in bladder pressure. This was followed by a period of high frequency oscillations (HFOs) associated with maximal urethral relaxation and burst type EUS EMG activity. Administration of N-nitro-L-arginine (L-NOARG) 10 mg./kg. intravenously, a nitric oxide synthase inhibitor, reversibly decreased the magnitude (62 percent, p less than 0.05) and duration (40 percent, p less than 0.05) of reflex urethral relaxation (N = 7). In 4 additional experiments, L-NOARG (10 to 15 mg./kg. intravenously) completely eliminated reflex urethral relaxation during micturition, and this effect was reversed in all animals by the administration of L-arginine (100 to 150 mg./kg. intravenously). Administration of N-nitro-D-arginine (D-NOARG) (10 to 30 mg./kg. intravenously) had no effect on reflex urethral relaxation. Neuromuscular blockade (vecuronium bromide 5 mg./kg. intravenously) reversibly decreased resting urethral pressure and eliminated the HFOs. The urethral smooth muscle relaxation that remained after neuromuscular blockade was eliminated following administration of L-NOARG (10 mg./kg. intravenously) in 2 of 3 animals. These results suggest that reflex urethral responses during micturition involve changes in both smooth and striated muscle activity, and that the predominant neurotransmitter mechanisms that mediate reflex urethral smooth muscle relaxation involve NO.     

Neural Control of Urethral Outlet Activity in Vivo: Role of Nitric Oxide

The present study investigated the role of nitric oxide (NO) in the reflex changes in urethral outlet activity during micturition. Isovolumetric bladder contractions, urethral pressure and external urethral sphincter electromyogram (EUS EMG) activity were recorded independently in urethane-anesthetized rats. During reflex bladder contractions, the urethra exhibited reflex responses characterized by an initial decrease in urethral pressure in conjunction with a rise in bladder pressure. This was followed by a period of high frequency oscillations (HFOs) associated with maximal urethral relaxation and burst type EUS EMG activity. Administration of N-nitro-L-arginine (L-NOARG) 10 mg./kg. intravenously, a nitric oxide synthase inhibitor, reversibly decreased the magnitude (62 percent, p less than 0.05) and duration (40 percent, p less than 0.05) of reflex urethral relaxation (N = 7). In 4 additional experiments, L-NOARG (10 to 15 mg./kg. intravenously) completely eliminated reflex urethral relaxation during micturition, and this effect was reversed in all animals by the administration of L-arginine (100 to 150 mg./kg. intravenously). Administration of N-nitro-D-arginine (D-NOARG) (10 to 30 mg./kg. intravenously) had no effect on reflex urethral relaxation. Neuromuscular blockade (vecuronium bromide 5 mg./kg. intravenously) reversibly decreased resting urethral pressure and eliminated the HFOs. The urethral smooth muscle relaxation that remained after neuromuscular blockade was eliminated following administration of L-NOARG (10 mg./kg. intravenously) in 2 of 3 animals. These results suggest that reflex urethral responses during micturition involve changes in both smooth and striated muscle activity, and that the predominant neurotransmitter mechanisms that mediate reflex urethral smooth muscle relaxation involve NO.     

Interference pattern in perineal muscles: A quantitative electromyographic study in patients before and after transurethral surgery of the prostate

The study aimed at assessing alterations in muscular activity in the external urethral sphincter when the internal sphincter located at the bladder neck was resected during TUR-P, and at determining whether activity in the external urethral sphincter increased to compensate for the loss of the internal sphincter. Perineal muscles were examined with quantitative EMG recordings, including interference pattern and fiber density before and after surgery. Fiber density increased in the external urethral sphincter after surgery. This indicates a reinnervation in the muscle, probably due to a peripheral nerve lesion that occurs during TUR-P, and may also explain the reduction in penile erectibility observed after surgery. The lack of compensatory activity in the external urethral sphincter expressed as unchanged number of turns may be explained as a disturbed feedback mechanism and a decreased central activation or to the lithotomy position at examination. The internal part of the external sphincter not available for measurement may compensate for the loss in bladder-neck sphincter function. Neurourol. Urodynam. 16:101–109, 1997. © 1997 Wiley-Liss, Inc.