Urodynamic findings in the lower urinary tract: I. Stress-incontinent vs. -continent women

Urodynamic findings in 250 patients with objective stress incontinence were compared with those of 108 controls without abnormalities. Patients with any component of motor-urge incontinence were discarded from the study. The results were as follows: abdominal straining to void was significantly higher in the stress-incontinent group; urethral resistance. maximal urethral closure pressure, and the relative urethral leakage pressure was significantly lower in the stress-incontinent group. In light of the higher incidence of inefficient voiding pallerns seen in the stress-incontinent population, preoperative urodynamic evaluation including cystometry with pressure flow studies, is important to exclude or at least be aware of the possibility of postoperative bladder-emptying problems—apart from the need to exclude underlying motor instability. Relative urethral leakage pressure measurements were significantly lower than maximal urethral closure pressure measurements in stress-incontinent patients. Urethral closure pressure profilometry is recommended in patients who are considered for retropubic urethropexy.     

Botulinum toxin for the treatment of lower urinary tract symptoms: a review

AIMS: To review the available literature on the application of botulinum toxin in the urinary tract, with particular reference to its use in treating detrusor overactivity (DO). METHODS: Botulinum toxin, overactive bladder (OAB), detrusor instability, DO, detrusor sphincter dyssynergia (DSD), and lower urinary tract dysfunction were used on Medline Services as a source of articles for the review process. RESULTS: DO poses a significant burden on patients and their quality of life. Traditionally patients have been treated with anti-cholinergic drugs if symptomatic, however, a significant number find this treatment either ineffective or intolerable due to side effects. Recent developments in this field have instigated new treatment options, including botulinum toxin, for patients' refractory to first line medication. Botulinum toxin, one of the most poisonous substances known to man, is a neurotoxin produced by the bacterium Clostridium botulinum. Botulinum toxin injections into the external urethral sphincter to treat detrusor sphincter dyssynergia has been successfully used for some years but recently its use has expanded to include voiding dysfunction. Intradetrusal injections of botulinum toxin into patients with detrusor overactivity and symptoms of the overactive bladder have resulted in significant increases in mean maximum cystometric capacity and detrusor compliance with a reduction in mean maximum detrusor pressures. Subjective and objective assessments in these patients has shown significant improvements that last for 9-12 months. Repeated injections have had the same sustained benefits. CONCLUSIONS: Application of botulinum toxin in the lower urinary tract has produced promising results in treating lower urinary tract dysfunction, which needs further evaluation with randomised, placebo-controlled trials.     

Total and static pressure measurements of the male lower urinary tract

Simultaneous total and static urethral pressure measurements were attempted in 22 male subjects who could void around a 10-French bilumen urethral catheter. The catheter had an end-hole at its tip and a side-hole approximately 1 cm away from the end hole (short catheter-tip segment). Thus, during a single voiding attempt, simultaneous total and static urethral pressures at two different urethral sites (1 cm distance) could be recorded. In addition, suprapubic vesical pressure monitoring was done in all these subjects. The studies also included a comparison of these recordings with those obtained with a 10-French catheter that had its side-hole placed 10 cm away from the tip (long catheter-tip segment). The studies indicated that (1) the total pressure at a particular region of the urethra was usually higher than its static pressure; (2) the pressure sensing catheters produced “plugging effect” of the narrow segments of the outlet; and (3) the static pressure configurations that were obtained with a catheter having a long catheter-tip segment were markedly different from those obtained through a catheter that had a short catheter-tip segment. This presentation also includes observations on static pressure measurements obtained from a crude mechanical model that simulated the geometry of the urinary bladder and its outlet. True lateral pressures of the flowing fluid were obtained via cannulae inserted perpendicularly into the stream, through the wall of the outlet (extraluminal route). A comparison was attempted between the static pressure measurements obtained through the extraluminal route with those obtained through the catheters (10–14 French) that were directly inserted into the lumen of the outlet along its axis (intraluminal route). The studies indicated identical static pressures at the narrowest site (16–18 French) of the outlet recorded through both routes.     

Congenital abnormalities of the lower urinary tract

Congenital anomalies of the lower urinary tract and genitalia (such as hypospadias) are common, but the group comprises some conditions which are rare (such as the exstrophy–epispadias sequence) and whose surgical treatment is challenging. The breadth of conditions encountered in routine and specialized paediatric urological practice is described.     

Physiological fatigue of smooth muscle contractions in rat urinary bladder

OBJECTIVE: To characterize the physiological fatigue in bladder smooth muscles that can occur within 60 s of stimulation, which is closer to the duration of normal voiding. MATERIALS AND METHODS: Longitudinal and transverse strips of rat bladder were used; the muscles were mounted in an in vitro multi-muscle chamber, and the decline in contractile tension recorded during continuous electrical stimulation at frequencies of 5-30 Hz for 60 s. The effect of muscle length on fatigue was assessed by monitoring the decline in tension during 30 Hz stimulation at rest length, and at 60% and 100% stretched lengths of the bladder strips. To assess some of the factors involved in the development of fatigue, tension responses of fatigued muscles were monitored on exposure to 80 mm potassium or 1 microm bethanechol. RESULTS: In both longitudinal and transverse bladder strips stimulated at 30 Hz, peak contractile tension declined to 50% of original after approximately 33 s, and to 30% after 60 s of stimulation. After 10 s rest, 60% of the original tension was recovered. Increasing the frequency of fatigue stimulation from 5 to 30 Hz significantly increased the extent of the decline in tension and reduced the time to a 50% decrease in tension. Stretching the bladder strips from rest length to 100% stretched length significantly reduced the extent of tension decline and increased the time to a 50% decrease in tension. Exposure of fatigued muscles to high potassium or bethanechol generated more tension than electrical stimulation. CONCLUSION: Contractile fatigue occurs in both longitudinal and transverse strips of the bladder smooth muscles within the duration of normal voiding. Increasing the frequency of stimulation from 5 to 30 Hz increased the degree and rate of fatigue. Stretching the bladder strips from rest length by 60-100% reduced the degree and rate of fatigue. Bladder fatigue may be caused by decreased depolarization of the smooth muscle membranes, reduced release of acetylcholine from presynaptic nerve terminals, or by other yet undetermined mechanisms.     

Central autonomic innervation of the lower urinary tract – a neuroanatomy study

Knowledge about the central innervation of the lower urinary tract is limited. The spinal cord and the pontine micturition center have been investigated most thoroughly, whereas higher centers have received little attention. Pseudorabies virus (PRV), a self-amplifying and transneuronal tracer was injected into the bladder trigone of 21 Sprague-Dawley rats. The animals were killed after 72, 96, and 120 h. The whole CNS was sectioned and immunostained for PRV. CNS centers directly connected to the bladder include the intermedio lateral cell column, the central autonomic nucleus, and the nucleus intercalatus at the spinal cord levels T12–L2 and L6–S2. The raphe pallidus et magnus, the A5 noradrenergic area, the pontine micturition center, the locus coeruleus, the periaquaductal gray, the nucleus para- et periventricularis of the hypothalamus, the red nucleus, the medial preoptic area, and the cortex are supraspinal centers connected to the bladder. Lower urinary tract function is a complex multilevel and multineuronal interaction. It involves facilitation and inhibition at many levels of the CNS.     

Anatomy of the lower urinary tract

The lower urinary tract (LUT) comprises the bladder and urethra in females with the addition of the prostate in males. The function of the lower tract is the low-pressure non-volitional storage of urine it receives from the upper urinary tract followed by the voluntary expulsion of urine when socially acceptable. The LUT may be affected by functional disorders such as bladder overactivity and urinary incontinence or by obstructive disorders such as prostatic enlargement and stricture disease or alternatively by other pathologies such as carcinoma and lithiasis. A thorough knowledge and understanding of the relevant anatomy is essential in understanding the various pathophysiological mechanisms of LUT disorders and their appropriate management. We describe the anatomy of the male and female LUT between which considerable differences exist in structure and function, in addition to summarizing the histology, vasculature and neural innervation of the organs comprising the LUT.     

The innervation of the external urethral sphincter; An ultrastructural study in male human subjects

Summary Innervation of the external urethral sphincter (EUS) was studied in male human subjects. In the region of EUS at the distal end of prostatic urethra, a large axon bundle surrounded by perineurium was evident in the intramural connective tissue gap. Because of the presence of dense core vesicles, the small nonmyelinated axon profiles in the bundle were considered to be adrenergic. After ramifications to smooth musculature, the axons were traced to the EUS. In the EUS, axon bundles containing many nonmyelinated axons were recognized as a sole autonomic nerve among the striated muscle cells. A single or at most two or three axons were surrounded by a Schwann cell, and some possessed dense core vesicles which suggested an adrenergic function. These autonomic adrenergic nerve ends formed surface junctions with the striated muscle of EUS. The clinical relevance of these data are discussed.     

The innervation and function of the lower urinary tract

Vesical and urethral function are closely controlled by neural activity, both reflex and volitional. Relatively subtle abnormalities have serious consequences. Understanding of the natural history of neurogenic vesical dysfunction has improved over the past few years and is summarized in this review article.     

A 20‐year follow‐up of the mesh wallstent in the treatment of detrusor external sphincter dyssynergia in patients with spinal cord injury

Study Type – Therapy (case series)
Level of Evidence 4

OBJECTIVE

To assess the long‐term (20 years) effectiveness of the UroLume wallstent^TM (Pfizer Inc., UK) in the treatment of detrusor external sphincter dyssynergia (DESD) in patients with spinal cord injury (SCI).

PATIENTS AND METHODS

Twelve patients with quadriplegia secondary to SCI underwent external striated sphincter stenting with the UroLume wallstent in place of sphincterotomy for DESD ≈ 20 years ago. The mean (range) age was 41.8 (26–65) years. Eleven patients had cervical level injury whilst one had a thoracic injury. All the patients were shown to have high‐pressure neurogenic detrusor overactivity and DESD with incomplete emptying on preoperative video‐cystometrograms (VCMG).

RESULTS

Six of the 12 patients have now been followed‐up for a mean (range) of 20 (19–21) years. Of the remaining six, two were lost to follow‐up at 1 and 3 years, but both remained free of complications during that time. Two patients developed encrustation causing obstruction, requiring stent removal within 1 year of insertion. Another patient with an adequately functioning stent died 7 years after stent insertion from a chest infection. The twelfth patient developed bladder cancer 14 years after stent insertion and underwent cystectomy with urinary diversion. VCMG follow‐up of the six patients showed a significantly sustained reduction of maximum detrusor pressure and duration of detrusor contraction at the 20‐year follow‐up. Five of these six patients developed bladder neck dyssynergia of varying degrees as shown on VCMG within the first 9 years of follow‐up. All were successfully treated with bladder neck incision (BNI) where the last BNI needed was at 12 years. We did not encounter any problem with stent migration, urethral erosion, erectile dysfunction or autonomic dysreflexia.

CONCLUSION

Urethral stenting using the UroLume wallstent is effective in the management of DESD in patients with SCI and provides an acceptable long‐term (20‐year follow‐up) alternative to sphincterotomy. The failures manifest within the first few years and can be managed easily with stent removal without any significant problems. Bladder neck dyssynergia was the long‐term complication which was treated successfully with BNI. It has no significant interference with erectile function, being reversible, minimally invasive and has a shorter hospital stay.     

Congenital abnormalities of the lower urinary tract: infravesical anomalies

Abnormalities of the lower urinary tract may range from frequent and very minor with no significant consequences to the rare but severe requiring major intervention and lifelong monitoring. While discussion of all infravesical congenital abnormalities of the lower urinary tract is beyond the scope of this article, the main abnormalities encountered in clinical practice are listed and discussed.