Urethral sphincter dysfunction

Burnett, A.L., Calvin, D.C., Chamness, S.L., Liu, J.X., Nelson, R.J., Klein, S.L., Dawson, V.L., Dawson, T.M., Snyder, S.H. Urinary bladder-urethral sphincter dysfunction in mice with targeted disruption of neuronal nitric oxide synthase models idiopathic voiding disorders in humans, Nat. Med. 1997, 3, 571-574. 

Urethral sphincter dysfunction which is due to various causes including weakness of the muscles and ligaments around the bladder neck, descent of the urethrovesical junction and periurethral fibrosis the result is stress incontinence. 

There is one report of the use of the tricyclic antidepressant imipramine hydrochloride to control urospermia in a stallion with detrusor dysfunction and decreased urethral sphincter tone (Oristaglio Turner et al 1995 see Ch. 11). Imipramine is a phe-nothiazine analog and appears to have a adrenergic effects via the blockade of norepinephrine reuptake at nerve terminals. It was administered orally at 0.8 mg/kg to this stallion 2-3 h prior to semen collection and was thought to improve urethral sphincter tone and limit urospermia. However, this improvement was not documented using urethral pressure profilometry and the owner of the stallion was also instructed to collect from the stallion shortly after it was observed to urinate. Consequently, it is not clear whether the imipramine treatment was really of any benefit. 

The bladder neck is the poorly delineated junction between the bladder and urethra at the level of the internal urethral sphincter. At the beginning of voiding the bladder floor descends and becomes funnel-shaped and in continuity with the proximal urethra. At the end of voiding, the bladder base ascends to its normal position. A wide bladder neck and a dilated proximal urethra during voiding (wide bladder neck anomaly and spinning top urethra, respectively) are variants that will be discussed in Chapter 14 on nonneurogenic bladder-sphincter dysfunction (functional disorders of the lower urinary tract). 

Extremely rare in childhood, the urethral polyp is usually solitary and consists of a pedunculated structure, originating from the posterior urethra, developing in the bladder neck, which can prolapse in the urethra during micturition (Foster and Garrett 1986). Hematuria, nonneurogenic bladder-sphincter dysfunction and infection may reveal the abnormality. On ultrasound, it appears echo-genic. The main differential diagnosis of urethral polyp is an ectopic ureterocele that has ruptured either spontaneously (Fig. 6.8) or after endoscopic... 

In addition, numerous definitions and categories are in use for nonneurogenic bladder-sphincter dysfunction, blaming either the bladder or the urethral sphincter for the various clinical expressions of nonneurogenic bladder sphincter-dysfunction. In this chapter not only the whole spectrum of nonneurogenic bladder-sphincter dysfunction will be described, but how dysfunction is embedded into the disease complex UTI-renal damage will be shown. Furthermore, the associations and the causal relationship to VUR, UTI, renal damage and constipation will be discussed and the various clinical manifestations will be elucidated. 

A broad spectrum of terms such as nonneuro-pathic vesicourethral dysfunction (Koff 1984), overactivity of the bladder and striated urethral muscle (Van Gool et al. 1984), nonneuropathic or nonneurogenic bladder-sphincter dysfunction (Hoebeke et al. 1999), dysfunctional bladder (Hinman 1986), unstable bladder (Koff 1982), nonneurogenic neurogenic bladder (Allen 1977) and Hinman syndrome (Hinman 1986) is still in use for sometimes overlapping patterns of nonneurogenic bladder-sphincter dysfunction. 

Hoebeke et al. (2001) in a publication about 1,000 videourodynamic studies in children with nonneurogenic bladder dysfunction found urge syndrome (overactive bladder or unstable bladder) in 58% (male female ratio 58 42), dysfunctional voiding (overactivity of the external urethral sphincter) in 32% (male female ratio 49 51) and lazy bladder in 4% (male female ratio 20 80). Furthermore, he found that the age distribution provided evidence against a dysfunction sequence as mentioned above. 

In about 70% of cases this dysfunction leads to (urge) incontinence, which is clinically manifested as wetting (mostly daytime, but nighttime as well). But even in severe cases the obligatory voluntary contraction of the striated urethral sphincter against the contracting detrusor can prevent leakage in up to 30% of cases. 

Fecal and urinary incontinence are significantly more commonly observed in constipated than non-constipated children. Constipation and/or encopresis is commonly associated with nonneurogenic bladder-sphincter dysfunction. Comprehensive treatment is mandatory for successful management of affected children. Idiopathic urethritis might be a manifestation of underlying dysfunctional elimination syndromes. 

The combination of a transient opening of the bladder neck with a flow of contrast material into the posterior urethra up to the voluntarily contracted striated urethral sphincter (Potter et al. 1986 Passerini-Glazel et al. 1992) together with cessation and/or back-up of contrast material drip flow suggests the presence of an uninhibited detrusor contraction (Fig. 14.3). These findings are valid they can stand alone without urodynamic results. Modified VCU allows detection of the majority of these dysfunctions in neonates, infants and small children with the same reliability and in the same way as in older age groups. 

Fig. 6.7. a VCU in a 7-year-old boy with dysuria, showing extrinsic compression of the urethra due to abnormal sphincter contraction during micturition. This functional anomaly should not be mistaken for posterior urethral valves. Urody-namic studies favor dysfunctional voiding with bladder-sphincter dyscoordination during voiding. Biofeedback physiotherapy was carried out. Clinical outcome was favorable, b Follow-up VCU shows normalization of urethral anatomy during... 

---