Sivert Lindström

A bladder-to-bladder cooling reflex in the cat.

1. Reflex effects of cold stimulation of the lower urinary tract were studied in cats anaesthetized with alpha‐chloralose. The bladder and the urethra were catheterized for separate fluid instillations and the bladder pressure was monitored together with the evoked efferent nerve responses in pelvic nerve filaments. 2. A bladder cooling reflex could be evoked from both the bladder and the urethra. The response was an efferent discharge in preganglionic pelvic motor fibres to the bladder. 3. Bladder mechanoreceptors that drive the normal micturition reflex were not directly involved in the cooling reflex. Their tension sensitivity was decreased by cooling and the efferent reflex response typically occurred before any activation of these receptors. The efferent activity of the cooling reflex also survived an intentional unloading of the mechanoreceptors, a manipulation that abolishes the normal micturition reflex. 4. The dynamic threshold temperature of the cooling reflex was about 30‐32 degrees C, which was at the thermal neutral point of the bladder in our experimental situation. 5. The bladder‐evoked component of the reflex was greatly reduced or abolished by an intravesical infusion of the local anaesthetic Xylocaine. It was also abolished by total bladder denervation. 6. The vesical component of the reflex was unchanged by bilateral transections of the hypogastric nerves but abolished by pelvic nerve transection. The cooling reflex from the distal urethra was abolished by transection of the pudendal nerves. 7. It was proposed that the cooling reflex originates from cold receptors in the bladder and urethral walls and that the responsible afferent fibres are unmyelinated C fibres. The function of the reflex may be to rid the body of a thermal ballast when under cooling stress.

THE BLADDER COOLING REFLEX AND THE USE OF COOLING AS STIMULUS TO THE LOWER URINARY TRACT

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.

Intravesical Electrical Stimulation—An Experimental Analysis of The Mechanism of Action

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.

The C fibre reflex of the cat urinary bladder

1 Reflexes evoked in bladder parasympathetic neurones by electrical stimulation of bladder C afferent fibres were studied in cats anaesthetized with α‐chloralose. The responses were compared with the ordinary micturition reflex evoked by low‐threshold Aδ afferents from bladder mechanoreceptors and mediated by a spino‐ponto‐spinal reflex pathway. 2 The bladder was catheterized for fluid instillations and pressure recordings. Efferent reflex discharges were recorded from the cut central end of a small distal bladder branch of the pelvic nerve. The remaining bladder pelvic nerve branches were stimulated electrically close to the bladder. 3 Stimulation at C afferent intensity evoked a late reflex discharge in bladder pelvic efferents in all animals. The response was centrally mediated, had a latency of 150−250 ms, and was much weaker after stimulation on the contralateral nerve. 4 The bladder C fibre reflex differed in several functional aspects from the ordinary Aδ micturition reflex. It could be evoked at a low rate of stimulation, with an empty bladder and no background activity from bladder mechanoreceptors. In this situation, the normal Aδ micturition reflex is not elicited. The C fibre reflex also survived an acute spinalization at a low thoracic level. 5 The C fibre reflex was strongly inhibited by dorsal clitoris or dorsal penis nerve stimulation, an effect that was maintained after spinalization. It was facilitated by bladder or urethra exposure to cold and menthol, stimuli that activate specific cold‐sensitive receptors associated with unmyelinated C afferents. 6 It is concluded that the central pathway of the C fibre reflex is spinal and partly separate from that of the ordinary micturition reflex. These observations are in keeping with the clinical finding that a bladder cooling reflex can be elicited in patients with disturbed descending control of the bladder.

Traditional Acupuncture and Electrical Stimulation of the Posterior Tibial Nerve: A Trial in Chronic Interstitial Cystitis

A prospective study on the symptomatic effect of traditional Chinese acupuncture treatment and transcutaneous nerve stimulation (TENS) of the tibial nerve in patients with interstitial cystitis is presented. There was no difference in voiding frequency, mean voided volume, maximal voided volume or visual analogue scale symptom scores before or after treatment with either TENS or acupuncture. Only one patient became improved both subjectively and objectively after acupuncture for a short period of time. Even though the present material involves a small group of patients, it seems that the two methods, as applied in this study, have a very limited effect in patients with interstitial cystitis.

Comparison of experimental nerve injury caused by ultrasonically activated scalpel and electrosurgery

Iatrogenic nerve injury caused by heat from dissection instruments is a significant problem in many areas of surgery. The aim of the present study was to compare the risk of nerve injury for three different dissection instruments: monopolar and bipolar electrosurgery (ES) and an ultrasonically activated (US) instrument.

Positive Bladder Cooling Test in Neurologically Normal Young Children

The bladder cooling test, which consists of rapid infusion of 0 to 8C saline into the bladder with simultaneous pressure measurement, was performed in 50 neurologically intact infants and children 6 months to 13 years old. The patients were referred for urodynamic investigation because of various disorders of the lower urinary tract. A positive bladder cooling test was defined as a sustained reflex detrusor contraction of about the same magnitude as the micturition contraction. The test was positive during the first 4 years of life but typically negative in children older than 5 years. These findings indicate that a positive bladder cooling test is an infant reflex response that, with the maturation of the central nervous system, becomes suppressed by descending signals from higher centers.

Paired pulse facilitation of corticogeniculate EPSCs in the dorsal lateral geniculate nucleus of the rat investigated in vitro.

To investigate paired pulse facilitation of corticogeniculate EPSCs, whole‐cell patch‐clamp recordings were made from principal cells in the rat dorsal lateral geniculate nucleus (dLGN) in vitro. Thalamic slices, oriented so that both corticogeniculate and retinogeniculate axons could be stimulated, were cut from young (16‐ to 37‐day‐old) DA‐HAN rats. Corticogeniculate EPSCs displayed pronounced paired pulse facilitation at stimulus intervals up to 400 ms. The facilitation had a fast and a slow component of decay with time constants of 12 ± 7 and 164 ± 47 ms (means ±s.d.), respectively. Maximum paired pulse ratio (EPSC2× EPSC1−1) was 3.7 ± 1.1 at the 20‐30 ms interval. Similar to other systems, the facilitation was presynaptic. Retinogeniculate EPSCs recorded in the same dLGN cells displayed paired pulse depression at intervals up to at least 700 ms. The two types of EPSCs differed in their calcium response curves. At normal [Ca2+]o, the corticogeniculate synapse functioned over the early rising part of a Hill function, while the retinogeniculate synapse operated over the middle and upper parts of the curve. The paired pulse ratio of corticogeniculate EPSCs was maximal at physiological [Ca2+]o. The facilitation is proposed to have an important role in the function of the corticogeniculate circuit as a neuronal amplifier.

Prolonged increase in micturition threshold volume by anogenital afferent stimulation in the rat

To determine whether induced bladder contractions influence the modulation by intravesical electrical stimulation (IVES) of the micturition reflex in anaesthetized rats, and to identify the optimal IVES frequency and duration.

Voiding pattern in healthy newborns

A 4‐hour observation period has been used in infants to investigate suspected bladder dysfunction. The aim of the present study was to extend the usefulness of this protocol by establishing reference values for voiding frequency, intervals, volumes, and residual urine in healthy newborns. The study included 51 healthy newborns, 26 girls and 25 boys, aged 3 to 14 days. During a 4‐hour period, all micturitions and residuals were recorded as well as feeding, sleeping, crying, and defecations. The observation was completed with the child undressed to observe the urinary stream during one void. Different provocation tests were tried to induce urinary leakage. All newborns voided with a stream, about once per hour, with a median volume of 23 mL. For each voiding parameter, there was a large inter‐ and intra‐individual variability. Double voidings were common as well as sizable residual volumes. The diuresis was about six times higher than in healthy school children. The healthy newborns did not leak during provocation tests such as manual compression of the bladder. Neurourol. Urodynam. 19:177–184, 2000.