Search

Purpose: We explored the role of bladder mechanoreceptors in post-void residual urine in rats with bladder outlet obstruction., Materials and Methods: Partial bladder outlet obstruction was induced by a urethral ligature in 11 adult female Sprague-Dawley® rats. Nine sham operated rats served as controls. The outcome was evaluated in acute experiments using α-chloralose anesthesia 6 weeks later. Bladders were catheterized for infusion, pressure recording and intravesical electrical stimulation. Bladder efferent activity was recorded from a thin pelvic nerve branch close to the bladder. Micturition contractions were triggered at different bladder volumes by a brief train of electrical stimulation of bladder afferents while monitoring post-stimulus efferent activity and reflex bladder contractions. The degree of obstruction was assessed by bladder wet weight at the end of the experiment., Results: Bladder weight, micturition threshold volume, anatomical bladder capacity and peak contraction force were significantly increased in obstructed rats. In sham operated controls a triggered micturition reflex was sustained by afferent feedback from the bladder until the bladder was empty. In contrast, reflex discharges failed with substantial volume remaining in the bladder in obstructed rats. The minimal micturition reflex volume correlated positively with bladder weight, micturition threshold volume and maximal bladder capacity (r ≥0.74)., Conclusions: In rats with partial bladder outlet obstruction the micturition reflex failed before the bladder was empty due to a decreased afferent drive from bladder mechanoreceptors. Similar changes may contribute to post-void residual urine in humans with bladder outlet obstruction., (Copyright © 2012 American Urological Association Education and Research, Inc. Published by Elsevier Inc. All rights reserved.)

Purpose: We assessed the bladder cooling reflex in the awake cat. The bladder cooling reflex is consistently observed in anesthetized adult cats but not in awake, neurologically normal humans. This discrepancy could indicate a state dependant control of the reflex or a species difference. This study was designed to differentiate between these alternatives,, Materials and Methods: Under ketamine-xylazine 5 animals had an indwelling catheter inserted into the bladder. The cooling reflex was tested by injections of cold saline into the bladder (4C to 8C), lowering its wall temperature to about 30C to 32C. The volume used (5 ml) was subthreshold for the Adelta micturition reflex, as confirmed by control injections of body warm saline. The procedure was repeated with the animals fully awake and it was well tolerated by all of them. Reflex responses were assessed by induced bladder pressures., Results: Typical bladder cooling reflexes with peak pressures greater than 3 kPa were evoked in all cats when in narcotic sleep (group mean +/- CI 7.4 +/- 3.1 kPa). No such reflexes were elicited when the animals were awake (2.0 +/- 1.0 kPa). The difference was significant at the level of individual animals., Conclusions: The bladder cooling reflex is suppressed in adult cats during wakefulness, as in humans. This state dependent control of the bladder cooling reflex adds to its resemblance to the extensor plantar response (Babinski's sign).

Purpose: The bladder cooling test (BCT) engages a primitive neonatal spinal reflex that becomes suppressed by descending signals in older children and may reappear with suprasacral lesions. We assessed the outcome of the BCT in a large group of children with nonneurogenic bladder problems., Materials and Methods: The BCT was evaluated in a consecutive series of 178 girls and 106 boys, 1 month to 18 years old with bladder problems without overt neurology. The test was performed at the end of routine cystometry by a rapid control infusion of body warm saline followed, after fluid evacuation, by the same volume of cold saline (3 to 10C). The test was considered positive if a detrusor contraction greater than 30 cm H2O was evoked by the cold but not the warm fluid., Results: Most children younger than 4 years had a history of pyelonephritis (29 of 34) and/or had vesicoureteral reflux (grade IV to V in 26 of 34). For those younger than 2 years 87% of the BCTs were positive while only 21% of the tests were positive in 2 to 3-year-old children. Most children older than 4 years had idiopathic urge incontinence, and greater than 50% of the BCTs were positive in the youngest (less than 6 years) with a gradual decline to 0% at age 13 years., Conclusions: Conversion of positive to negative BCTs at about age 2 years presumably represents normal maturation while positive tests in older incontinent children suggest delayed maturation of the central neuronal control of the bladder.

Purpose: We review the physiology of bladder cooling response in experimental animals and humans, and present its clinical usefulness., Materials and Methods: We describe experimental studies of the bladder cooling response, and more recent clinical retrospective and prospective studies of the bladder cooling test in adults and children., Results: Studies indicate the existence of a segmental spinal bladder cooling reflex that originates from specific cold receptors in the bladder and urethral walls supplied by unmyelinated C-afferents. The reflex is positive in neurologically normal infants and children until about age 4 years. It becomes negative with further maturation of the nervous system but may be unmasked by pathological processes that disturb the descending neuronal control of normal voiding. A positive test in a patient with an overactive bladder requires further neurourological evaluation., Conclusions: The bladder cooling response originates from cold receptors within the walls of the lower urinary tract. The cooling response represents a neonatal reflex that may be unmasked by central neuropathology, analogous to the appearance of the Basbinki sign in pyramidal tract lesions. The bladder cooling test is a simple and valuable tool to support the diagnosis of neurourological disorders.

Purpose: We evaluated the diagnostic use of the bladder cooling test in children with neurogenic bladder dysfunction., Materials and Methods: We performed 201 bladder cooling tests in 65 female and 43 male patients 5 days to 17 years old, including 70 with myelomeningocele, 12 with high spinal lesions, 9 with sacral spinal lesions and 17 with encephalopathy of various types. At the end of routine cystometry we rapidly infused body temperature saline to approximately a third of cystometric capacity, followed by the same volume of saline at 4 to 8C. The test was considered positive when a detrusor contraction greater than 30 cm. water was evoked by the cold but not the warm infusion., Results: The bladder cooling test was positive in 37 children younger than 4 years, at which age it is normally positive. The test was negative in only 2 patients, indicating a complete lower motor neuron lesion. It was positive in 34 of the 57 children older than 6 years, at which age it should be negative. Thus, the positive bladder cooling test confirmed neurogenic bladder dysfunction. Four of the 20 children with a negative test voided normally, while the remainder had no voiding contractions, suggesting a nonfunctional spinal sacral reflex arch to the bladder., Conclusions: The bladder cooling test is a simple, reliable assessment that may serve to demonstrate a functional sacral reflex arch in young patients without voiding contractions or confirm a suspected lower motor neuron lesion. It may be used longitudinally to demonstrate changes in bladder function with growth.

Purpose: Intravesical electrical stimulation (IVES) has been used clinically to treat patients with voiding disorders. The aim of the present experimental study was to obtain objective evidence of a modulation of the micturition reflex by intravesical electrical stimulation (IVES)., Materials and Methods: Forty-one female rats, anesthetized by alpha-chloralose were used for the experiments. Intravesical electrical stimulation was given by a catheter electrode in the bladder (5 minutes of continuous stimulation at 20 Hz, 7 to 11 mA). The effect was evaluated by the change in cystometric micturition threshold volume., Results: The threshold volume of the micturition reflex decreased significantly to 82% of controls after IVES (p<0.001; n=31). The effect was reversible and lasted for about 1 hour. The decrease was prevented by a transient blockade of the bladder nerves during IVES., Conclusions: Intravesical electrical stimulation induced a prolonged modulation of the micturition reflex in anesthetized rats. The effect was due to activation of bladder mechanoreceptor afferents and remained long after the period of stimulation. It is proposed that the modulation was due to a prolonged enhancement of excitatory synaptic transmission in the central micturition reflex pathway. Such a modulation may underlie the curative effect of IVES in certain voiding disorders.

The working mechanism of intravesical electrical stimulation (IVES) was evaluated in alpha-chloralose anaesthetized cats and rats. IVES involved a direct activation of bladder mechanoreceptor afferents of the A delta type and as a consequence a central reflex activation of the detrusor. The detrusor response was abolished by bilateral transection of the S1-S3 dorsal roots and by intravesical instillation of lidocaine. The optimal stimulation frequency was 20 Hz. The results offer a theoretical rationale for the use of IVES as treatment of weak detrusor contractility in man.

Intravaginal electrical stimulation (IVS) induces a profound bladder inhibition and is successful in the treatment of incontinence due to detrusor instability. In this experimental study in cats, direct recordings of the efferent activity in thin hypogastric and pelvic nerve filaments to the bladder were used to analyze the neuronal mechanisms underlying this bladder inhibition. A longlasting reflex discharge, with a latency of 35 to 50 msec., was evoked in the hypogastric nerve by IVS. The reflex discharge was unaffected by imposed changes in intravesical pressure or by micturition contractions, but the response was very frequency-sensitive with an optimal transmission at about 5 Hz of stimulation. A "spontaneous" efferent activity could be recorded in the pelvic nerve filaments when the bladder pressure was elevated above 5 to 7 cm. H2O. The pelvic activity occurred in 10 to 20-second bursts, each followed by an abortive detrusor contraction. IVS of 5 to 10 Hz completely abolished this efferent pelvic activity by central inhibition. The findings are discussed in relation to the normal neuronal control of the bladder and to the clinical application of IVS.