Anatomy and Physiology of the Autonomic Nervous System
Kenneth J. Broadley in Autonomic Pharmacology, 2017
The simplest form of reflex occurs at the spinal level, without the need for central connections. These reflexes include those for emptying the bladder and rectum. Filling of these organs causes stimulation of stretch receptors in the walls, resulting in an increase in traffic of afferent impulses to the sacral spinal cord. On reaching a specific intensity, there is reflex contraction of the detrusor muscle of the bladder and increased peristalsis of the descending colon. The rectum and sigmoid colon contract vigorously, the internal anal sphincter (smooth muscle) relaxes and defaecation occurs. Normally, ascending pathways to the medulla transmit this information on fullness of the rectum and a voluntary decision can be made to inhibit defaecation. This is achieved by contraction of the external anal sphincter (skeletal muscle) and relaxation of the rectum and sigmoid colon which reduces the pressure and thus stimulation of stretch receptors. This may continue until the rectum is distended to the point where defaecation is unavoidable. In very young children this voluntary control of defaecation does not occur because the necessary nerve pathways have yet to reach full maturity. Similarly, in adults whose spinal cord is severed at or above the sacral level (paraplegics), voluntary control is lost and the reflex is purely spinal. The micturition reflex of the bladder operates in a similar fashion.
Intravesical pharmacologic treatment for neurogenic detrusor overactivity
Jacques Corcos, David Ginsberg, Gilles Karsenty in Textbook of the Neurogenic Bladder, 2015
Treatment for both DSD and NDO can include pharmacologic therapy, catheterization, and surgery. Currently available oral pharmacologic treatments are often insufficient or not well tolerated. Intravesical pharmacologic therapy offers a direct route of application to the bladder that can enhance therapeutic effect as well as improve patient compliance. This approach takes on greater significance given recent studies documenting the presence of several receptor/neurotransmitter systems at the level of the urothelium. In this chapter, we discuss three prominent mechanisms utilized to disrupt the micturition reflex by direct application to the bladder. Two classes of agents (i.e., urologics and botulinum toxin A [BoNT-A]) are available commercially, whereas one class (i.e., vanilloids), while clinically promising, remains investigational in nature.
Physiology of Micturition
Linda Cardozo, Staskin David in Textbook of Female Urology and Urogynecology - Two-Volume Set, 2017
Role of BlAdder AnAtomy in Micturition Reflex The musculAr And membrAnous structure of blAdder is well suited for the storAge phAse of micturition thAt cAn lAst up to severAl hours in heAlthy individuAls. The storAge function of blAdder is therefore dependent on the stretching of A compliAnt blAdder wAll, which Allows it to store A sociAlly AdequAte volume of urine without significAnt rise in blAdder wAll tension. blAdder emptying requires A synchronous ActivAtion of All the smooth muscles. uneven spreAd of contrAction Across blAdder wAll mAy cAuse stretching of contrActed regions And prevent the rise in pressure necessAry for urine to be expelled through the urethrA. HistologicAl exAminAtion of the blAdder body reveAls thAt blAdder wAll is An interlAcing bundle of disorgAnized smooth muscle, where myofibrils Are ArrAnged into fAscicles in rAndom directions [5]. This Architecture differs from the discrete circulAr And longitudinAl smooth muscle lAyers in the ureter or gAstrointestinAl trAct. The blAdder outlet is composed of the blAdder bAse, urethrA, And externAl urethrAl sphincter (eus). The blAdder bAse hAs A lAminAr Architecture with A superficiAl longitudinAl lAyer lying beneAth the trigone. A muscle lAyer deep to the superficiAl lAyer is continuous with the detrusor [6–8] And the smAller muscle bundles in the blAdder bAse exhibit A predominAntly circulAr orientAtion. Detrusor smooth muscles hAve A broAd length–tension relAtionship, which Allows tension to be developed over A lArge
Pharmacological treatments available for the management of underactive bladder in neurological conditions
Published in Expert Review of Clinical Pharmacology, 2018
Seyedeh-Sanam Ladi-Seyedian, Behnam Nabavizadeh, Lida Sharifi-Rad, Abdol-Mohammad Kajbafzadeh
In the normal situation, micturition reflex initiates after maximal filling of bladder and consequent stretch in bladder wall. Afterwards, afferent nerves, brain circuits, and efferent nerves conduct the impulse, respectively, which leads to an effective and sustainable detrusor contraction. Sacral parasympathetic nucleus and pontine micturition center (PMC) facilitate this reflex [13]. PMC is normally inhibited by limbic system and in turn receives inputs from higher cortical centers. During the storage phase, afferent fibers are responsible for bladder volume monitoring. Intact bladder sensation is fundamental to initiate micturition reflex and efferent system action [21]. Magnitude of detrusor contraction during voiding is also regulated by afferent system [22]. Efferent pathway provides contraction of bladder detrusor and adjusts speed, magnitude, and duration of contraction [21]. It is intuitive that interruption of signaling in aforementioned pathways and regulatory centers could result in diminished, absent, or ineffective detrusor contractility. Therefore, a variety of neurogenic diseases and injuries could result in UAB. Among them brain strokes, multiple sclerosis, Parkinson’s disease, diabetes mellitus, and spinal cord injuries are the well-known neurogenic causes of UAB. There is also evidence that diminution of response occurs in brain regions (responsible for interpretation of sensory inputs from the bladder) as age increases [18].
Persistent Labial Minora Fusion in Reproductive Age Women: A Retrospective Case Series of Nine Patients and Review of Literature
Published in Organogenesis, 2021
Ze Liang, Juan Chen, Xin Yu, Lan Zhu
Of the 9 patients, 4 were found to have vulva/perineum deformity at the age of 0–3 (1.25 ± 1.09) years and persisted into the reproductive age, and the remaining 5 patients discovered the disease when they reached child-bearing age (25.20 ± 4.31). Regarding the patients of child-bearing age, the first symptoms were discovered during a physical examination (3/5), due to difficult coitus (1/5) or due to difficulties in voiding (1/5). A total of 5 patients (55.56%) mentioned “blood and urination from the urethral orifice” in their medical history. This symptom referred to a blood or blot clots drained from the same orifice as urine during the menstrual period. Two patients mentioned mild dysmenorrhea. Of all 9 patients, none reported having symptom of dysmenorrhea, and a blood CA125 level or ultrasound test found no support for endometriosis. One patient was found to have congenital defects. She was diagnosed with a double cervical and complete uterine septum by magnetic resonance imaging (MRI).
Existing and emerging applications for the neuromodulation of nerve activity through targeted delivery of electric stimuli
Published in International Journal of Neuroscience, 2019
Claire Ginn, Bipin Patel, Robert Walker
At this time the only SNS devices approved by the FDA for the treatment of OAB are InterStim and InterStim II by Medtronic and Axonics r-SNM by Autonomic Technologies. The exact mechanism of action of SNS in OAB is not completely understood. It has been suggested that SNS modulates the normal micturition reflex by stimulating the somatic afferent inhibition of sensory processing of the bladder within the spinal cord [80]. Another theory is that SNS may act to directly inhibit input to the bladder, which can cause inhibition of the guarding reflex, a decrease in pelvic floor specificity and improved non-obstructive urinary retention and dysfunctional voiding [80]. Latini et al. found that following SNS therapy 90% of the patients displayed a ≥50% improvement in symptoms and signs of urge incontinence as evidenced by voiding diaries (n = 41) [81]. The frequency of incontinence episodes also decreased from a mean of 8.8 per day to 2.3 per day at the 6-month follow-up [81]. A longer term study by Siegel et al. found that following 3 years of therapy using the InterStim device, 59% of 41 urinary urge incontinent patients showed ≥50% reduction in leaking episodes per day with 46% of patients being completely dry [79]. This was further corroborated by van Kerrebroeck et al. who found a decrease in urge incontinence episodes from 9.6, before implantation, to 4.7 at 1-year follow-up and an average of 3.9 episodes at the 5 year follow-up (n = 163) [82].
Related Knowledge Centers
- Autonomic Nervous System
- Bladder
- Central Nervous System
- Excretion
- Reflex
- Somatic Nervous System
- Urine
- Urethra
- Urinary System
- Pontine Micturition Center