Physiology of female micturition

Use of combined anticholinergic medication and sacral neuromodulation in the treatment of refractory overactive bladder

OBJECTIVES

: The objectives of this study were to determine the number of patients implanted with sacral neuromodulation (SNM) for overactive bladder (OAB) who required supplemental or continued anticholinergic (ACH) therapy for improved response and to identify factors predictive of requiring supplemental ACH.

MATERIALS AND METHODS

: This is a retrospective chart review of 148 patients who underwent SNM from 1999 to 2007. Patients included were those implanted for urgency, frequency, or urge incontinence. Eighty-eight patients were included in the analysis. A stepwise regression analysis was performed to identify factors predictive for restarting ACH medication.

RESULTS

: All patients underwent SNM implantation for frequency-urgency and urge incontinence. Of all patients, 16 (18%) required supplemental ACH therapy for improved symptom control. Overall, 26 patients (25%) either continued or were started on ACH therapy in addition to SNM for improved outcomes.

CONCLUSIONS

: A subset of patients had improved therapeutic response with combined SNM and ACH therapy. The only factor associated with supplemental ACH use was body mass index.

Overactive bladder symptoms and voiding dysfunction in neurologically normal women

AIMS

To understand mechanisms underlying overactive bladder (OAB) and voiding dysfunction (VD) in neurologically normal women.

METHODS

Review of MEDLINE from (1982) to (2011) using defined search terms, and manual analysis. Only articles published in English were included.

RESULTS

One in five women report moderate to severe lower urinary tract symptoms (LUTS). Whilst VD is more common in men, women report a higher rate of storage symptoms or post-micturition symptoms. Post-void residual (PVR) volume measurements are vital in the assessment of women with LUTS and patients with VD without stress incontinence (SUI) are likely to have an elevated PVR (82%). Bladder outlet obstruction (BOO) also causes VD in women and can be alleviated by surgery or alpha-blocker therapy, although OAB symptoms typically remain. Surgical repair for SUI can result in temporary VD in the minority of patients, highlighting the complex interplay that is emerging in the urethral bladder functioning complex in women.

CONCLUSIONS

Women with impaired bladder emptying present with a wide range of LUTS, and PVR measurement is essential for diagnosis. OAB and VD can clearly coexist and accurate diagnosis of underlying pathophysiology is required. Recommendations for clinical practice and research are provided including: investigation of VD in women with OAB; evaluation of PVR values to determine appropriate therapy and identification of BOO. There is clearly a need for further research into the impact of alpha-blockers in women with VD as well as an evaluation of PVR changes in women with OAB before and after antimuscarinic therapy.

Biomechanical characterization of the urethral musculature

Rigorous study of the associations between urethral structural anatomy and biomechanical function is necessary to advance the understanding of the development, progression, and treatment of urethral pathologies. An ex vivo model was utilized to define the relative biomechanical contributions of the active (muscle) elements of the female urethra relative to its passive (noncontractile) elements. Whole urethras from female, adult rats were tested under a range of applied intraluminal pressures (0 to 20 mmHg) as a laser micrometer simultaneously measured midurethral outer diameter. Active tissue characterization was performed during induced contraction of either smooth muscle alone ( Nω-nitro-l-arginine, phenylephrine), striated muscle alone (sodium nitroprusside, atropine, hexamethonium, acetylcholine), or during collective activation of both muscles ( Nω-nitro-l-arginine, phenylephrine, acetylcholine). The subsequent collection of paired passive biomechanical responses permitted the determination of parameters related to intrinsic muscle contractile function. Activation of each muscle layer significantly influenced the biomechanical responses of the tissue. Measures of muscle responsiveness over a wide range of sustained opposing pressures indicated that an activated striated muscle component was approximately one-third as effective as activated smooth muscle in resisting tissue deformation. The maximum circumferential stress generated by the striated muscle component under these conditions was also determined to be approximately one-third of that generated by the smooth muscle (748 ± 379 vs. 2,229 ± 409 N/m2). The experiments quantitatively reveal the relative influence of the intrinsic urethral smooth and striated muscle layers with regard to their effect on the mechanical properties and maximum functional responses of the urethra to applied intralumenal stresses in the complete absence of extrinsic influences.

Duloxetine: A balanced and selective norepinephrine- and serotonin-reuptake inhibitor

PURPOSE

The pharmacology, pharmacokinetics, efficacy, safety, drug interactions, dosage and administration, cost, and place in therapy of duloxetine for major depression, pain from diabetic peripheral neuropathy, and stress urinary incontinence are reviewed.

SUMMARY

Duloxetine is a balanced selective serotonin and norepinephrine-reuptake inhibitor available in the United States for the treatment of major depressive disorder (MDD) and diabetic peripheral neuropathic pain (DPNP). Duloxetine has also been used for the treatment of stress urinary incontinence (SUI). Absorption of duloxetine begins two hours after oral administration, reaching a maximum plasma concentration in six hours. Half-life and volume of distribution are 12 hours and 1640 L, respectively. The recommended dosage of duloxetine is 40-80 mg daily, depending on the indication, preferably split into two doses per day. For the treatment of major depression, duloxetine has achieved remission rates similar to that of existing selective serotonin-reuptake inhibitors (SSRIs). For SUI and pain associated with diabetic peripheral neuropathy, duloxetine has not demonstrated equivalence or superiority to existing therapies. The adverse effects of duloxetine are similar to those of traditional SSRIs. Nausea is common and has been cited as the primary reason for discontinuation of duloxetine in trials. Increases in blood pressure have been mild, but caution should be used in patients with hypertension. Patients with a creatinine clearance of <30 mL/min and patients with hepatic impairment should avoid duloxetine. Duloxetine should not be recommended as first-line therapy for SUI or DPNP. For MDD, duloxetine may be a useful alternative for patients who do not benefit from or are unable to tolerate other antidepressant therapy.

CONCLUSION

Duloxetine has been approved for the treatment of MDD and pain associated with diabetic peripheral neuropathy in adults.

Female voiding dysfunction

Female voiding dysfunction is poorly understood; it lacks standard definitions, and there is no consensus on diagnostic criteria. In the majority of women who are neurologically intact the cause is idiopathic. It affects the sufferers' quality of life, but unfortunately there is a paucity of published literature on its management. This review examines the current knowledge on the management of this common problem. Diagnosis is aimed at identifying the underlying aetiological factors, which are discussed, as well as the importance of a detailed history and focused physical examination. Investigations essential to management are outlined. Developments in the medical treatment of voiding dysfunction have been disappointing. The role of surgery is even more limited except for those with postoperative voiding problems after new-generation sling procedures. Intermittent self-catheterisation, supervised and supported by a dedicated nursing specialist, remains the mainstay of management. A multidisciplinary approach is essential to success. Emerging treatment modalities such as sacral and peripheral neuromodulation and the use of alpha(1)-blockers are discussed. Botulinum toxin A injections have been useful in some cases. There are relatively few publications on the effectiveness of these interventions in clinical practice. These issues need to be addressed by quality research. Female voiding dysfunction presents a challenge to urogynaecologists and urologists alike.