Effect of sacral nerve blocks on the function of the urinary bladder in humans

Transcription

1 Effect of sacral nerve blocks on the function of the urinary bladder in humans GAYLAN L. ROCKSWOLD, M.D., WILLIAM E. BRADLEY, M.D., AND SHELLEY N. CHOU, M.D. Departments of Neurosurgery and Neurology, University of Minnesota, Minneapolis, Minnesota The authors report over 100 sacral root blocks performed in 50 patients with detrusor activation by air cystometry. The detrusor reflex was abolished with unilateral sacral blocks in over 50% of the patients. The nerve roots most frequently innervating the bladder were S-3 and S-4. Most of these patients suffered from multiple sclerosis and had spinal cord involvement. The possible pathophysiology and its significance regarding urinary bladder innervation is discussed. KEY WORDS sacral nerve root block bladder parasympathetic nervous system detrusor muscle multiple sclerosis pelvic nerves spinal cord lesion mieturition TNNERVATION of the urinary bladder in humans has previously been studied.l mainly in human cadavers and, for comparison, in experimental animals. The evidence from such studies indicates that the main motor supply of the urinary bladder is parasympathetic in origin and arises from the sacral segments traveling over the ventral roots and pelvic nerves to the detrusor muscle. 4 The studies further suggest that the pelvic nerves also carry the afferent impulses essential for the micturition reflex since, following a sympathectomy that affects the bladder, patients continue to have a normal micturition pattern.~,l~,~ Harmon ~ concluded from cadaver dissections that the main outflow of the pelvic nerves was from S-3 while the outflow from S-2 and S-4 varied considerably in six human fetuses. Similar results were obtained by other investigators. 14,26,2s The consensus of the anatomical studies is that most fibers to the pelvic nerves arise from S-3 and S-4 with a variable number from S-2. Investigation of patients has provided information regarding the motor innervation of the bladder in humans. Heimburger, et al., ~'~ performed sacral nerve blocks in 12 traumatic paraplegic patients with hyperactive bladders, including studies of detrusor reflex activity before and after bilateral blocks of the desired nerve roots. Their findings revealed that the two third sacral roots provided the predominant innervation of the bladder in patients with complete or nearly complete spinal cord injury. Nagib, et al., 2~ described the results of direct stimulation of the ventral roots with cystometrogram control prior to sacral rhizotomy. In nine paraplegic patients they found that bladder contractions measured J. Neurosurg. / Volume 40 / January,

2 G. L. Rockswold, W. E. Bradley and S. N. Chou by rise in intravesical pressure were consistently obtained only by stimulating the roots at S-3 and S-4 separately. The contractions resulting from S-4 roots were usually more pronounced. Our experience with sacral root blocks indicates similar segmental innervation; however, in the majority of patients there was root predominance, and innervation was functionally unilateral. Material and Methods We have carried out 107 sacral nerve blocks in 50 patients. We selected patients with multiple sclerosis and voiding difficulties who had been studied by air cystometry, electromyography of the perineal muscles, and evaluation of urinary bladder innervation, 6 80% had a diagnosis of multiple sclerosis (Table 1). Informed consent was obtained from each patient after the nature of the procedure had been fully explained. Most suffered from frequency and urgency incontinence caused by low-threshold detrusor hyperreflexia 25 as demonstrated by air cystometry. 5 The typical cystometrogram (Fig. 1 left) revealed a marked increase in intravesical pressure with only a small volume of air introduced into the bladder. This sudden increase in pressure was due to an involuntary detrusor contraction and was associated clinically with the sensation of urgency and frequent precipitate voiding with little voluntary control. The bladder capacity was usually less than 100 cc. These TABLE 1 Original diagnosis of patients undergoing sacral nerve blocks Diagnosis No. of Cases % multiple sclerosis traumatic paraplegia 2 4 perineal pain 2 4 back pain 2 4 cervical spondylosis 1 2 parkinsonism 1 2 diabetes mellitus 1 2 postcraniotomy 1 2 total patients suffered from spinal cord involvement as a result of their demyelinating disease. The sacral nerves were anesthetized through a transsacral approach with the patient in the prone position. TM Approximately 3 to 5 cc of 1% xylocaine was used to anesthetize each sacral nerve. A baseline air cystometrogram was performed and then repeated after each individual sacral nerve block to determine the effect of the block on the detrusor reflex and bladder capacity. If there was no significant effect on the cystometrogram after 10 or 15 minutes, a second sacral nerve was blocked. This sequence was continued until the detrusor reflex, if present, was abolished and the bladder capacity significantly increased. Relevant dermatomes were checked for hypalgesia, and if there was apparent FIG. 1. Cystometric response following sacral nerve blocks. Left: Control cystometrogram showing an abnormally low threshold (+90 ml of air) detrusor hyperreflexia. Center: Cystometrogram following a unilateral S-2 block showing an increased threshold in the detrusor response (190 ml of air). Right: Cystometrogram following unilateral S-2 and S-3 blocks showing abolition of the detrusor reflex response Neurosurg. / Volume 40 / January, 1974

3 Effect of sacral nerve block on bladder TABLE 2 Effect of different methods of sacral nerve block on detrusor function Type of Detrusor Reflex Bladder Capacity No Block No. of Cases Abolished & Bladder Capacity Increased Increased Only Effect unilateral blocks on separate occasions 30 right side left side 7 1 either side 7 unilateral block on one side only right side left side simultaneous bilateral blocks total involvement of an adjacent dermatome this root was considered anesthetized also. In our experience, this was not an infrequent occurrence, probably due to diffusion of the anesthetic, since the sacral roots are in close proximity at any one sacral foramen. 18 An attempt was made to perform the right and left sacral root blocks on separate occasions in as many patients as possible. In some patients in whom multiple nerves were blocked before there was an effect on the cystometrogram, later attempts at abolishing the detrusor reflex were made by selectively blocking one or two sacral nerves. The effect of blocking two ipsilateral sacral nerves is seen in Fig. 1 right; the detrusor reflex was abolished and there was a marked increase in bladder capacity. Results The results of our series are summarized in Table 2. In 11 patients we abolished the detrusor reflex and significantly increased bladder capacity by unilateral sacral nerve blocks. A separate procedure on the opposite side on a second occasion produced no appreciable effect. In an additional eight patients unilateral sacral blocks abolished the detrusor reflex and increased bladder capacity but no attempt was later made to block the contralateral side. In seven patients unilateral blocks of either side abolished the detrusor reflex and increased bladder capacity. Thus, in 26 of 50 patients, or 52%, the detrusor reflex was abolished with unilateral sacral blocks. In seven patients who had bilateral blocks, no later attempt was made at selective unilateral blocks. It is possible that some of these patients also exhibited unilateral predominance in detrusor innervation. In six patients the detrusor reflex was abolished and/or the bladder capacity significantly increased by blocking a single sacral nerve. Anesthetizing two sacral nerves produced this effect in 17 patients. Tables 3 and 4 summarize the effect of anesthetizing various combinations of sacra/ nerves on the detrusor reflex and bladder capacity. There appears to be a definite predominance of the S-3 and S-4 nerve roots in detrusor innervation in these patients. Detrusor activity was effectively blocked by anesthetizing one or two sacral nerves in 28 instances; 23 of these involved S-3 and S-4 nerves either alone or in combination. The sacral nerve blocks have been used in the preoperative selection of patients for differential rhizotomyy ~ Where detrusor hyperactivity has been abolished by anesthetizing one or two sacral nerves, a partial anterior and posterior rhizotomy has been effective in significantly increasing bladder capacity while preserving detrusor reflex and sphincter function (Fig. 2). This has greatly improved the patients' symptoms of frequency and urgency incontinence. We have more recently begun to use sacral nerve blocks in evaluating neurological bladder disease of various etiologies (Table 1) and also for the evaluation of pain in the coccygeal and perineal areas. In J. Neurosurg. / Volume 40 / January,

4 G. L. Rockswold, W. E. Bradley and S. N. Chou TABLE 3 Effect of unilateral sacral nerve blocks on detrusor function Roots Blocked No. of Blocks S-2 1 S-3 5 S--4 4 S-2,-3 5 S-3, S-2,-3,-4 43 total 81 Detrusor Reflex Abolished Bladder Capacity No & Bladder Capacity Increased Increased Only Effect Right Left Right Left Right Left four of the 10 patients with a diagnosis other than multiple sclerosis we were able to abolish the detrusor reflex and increase bladder capacity with unilateral sacral blocks. In an additional four patients we were only able to increase bladder capacity since a detrusor reflex could not be consistently elicited. This was not unusual since in the normal person the reflex is often suppressed by the unfamiliar surroundings and by the discomfort and embarrassment of catheter insertion. In this last group three patients had perineal or back pain and normal neurological examinations. Discussion This study of the effect of sacral nerve blocks on the air cystometrogram is essentially an investigation of the effect of the block on an important component of the micturition reflex, namely, detrusor reflex contraction. Barrington 2 considered this the first reflex in a sequence of six responsible for micturition in the cat. The reflex stimulus was passive distension of the bladder, the afferent and efferent reflex pathway was via the pelvic nerves, and the response was a strong contraction of the TABLE 4 The effect of bilateral sacral nerve blocks on detrusor function Detrusor Reflex Roots No. of Abolished & Bladder Capacity No Blocked Blocks Bladder Capacity Increased Only Effect Increased S-3 bilat 1 S-3,--4 bilat S-2,-3,-4 bilat S-2,-3,--4 (It) (rt) 1 1 S-3,--4 (It) S-2,-3,--4 (rt) S-2,-3,--4 (It) S-3,--4 (rt) 1 1 S-3 (It) S-3,-4 (rt) 1 1 S-2,-3 (It) S-2,-3,--4 (rt) 2 2 S-2,-3,-4 (It) S--2,-3 (rt) total J. Neurosurg. / Volume 40 / January, 1974

5 Effect of sacral nerve block on bladder FIG. 2. Cystometrograms before (left) and after (right) partial section of S-3 and S-4. Bladder capacity has been significantly increased postoperatively while the detrusor reflex has remained intact. detrusor muscle producing an intravesical pressure rise. The reflex was abolished if the pelvic nerves of the eat were sectioned, the spinal cord divided either in the lower thoracic or upper cervical region, or if the bladder interior was eocainized. Nathan and Smith 21,22 determined that the principal afferent and efferent pathway for micturition in the spinal cord of man lay within the lateral columns. They based this conclusion on a careful correlation of a clinical evaluation of the patient with a postmortem histological examination of the spinal cord. They also concluded that unilateral lesions of the spinal cord pathways did not significantly interfere with voiding. Their findings are consistent with experimental investigations in animals, a,2r In experimental animals it has been coneluded that the detrusor reflex represents a brain-stem reflex which is long routed through the spinal cord. 7,s This varies considerably from the clinical concept of a reflex arc involving a voiding center in the sacral spinal cord on which descending inhibiting and facilitating impulses act. 9,1~ Our data are compatible with either concept. A pathological process such as a demyelinating disease could possibly interrupt long routed pathways, primarily unilaterally. A contralateral sacral nerve block would then interrupt the functioning side of this reflex arc, abolishing the detrusor reflex. In a study of the topographic distribution of plaques in the spinal cord in multiple sclerosis patients, Fog 11 found one of the sites of predilection to be the center and posterior two-thirds of the lateral columns. Although the plaques were mainly bilateral, the disease process was at a late stage. Certain multiple sclerosis patients may have predominantly unilateral plaques early in the course of the disease. Demyelinating plaques could also occur primarily unilaterally in the sacral segments. This could explain the effect of the unilateral blocks if the reflex arc ascended only to the sacral cord. However, one would then expect fairly frequent involvement of dorsal root entry zones with evidence of buttock numbness. This was not the case in the patients we studied. If long routing of this reflex to the brain stem is to be considered a valid hypothesis, an explanation for the establishment of a hyperactive detrusor reflex following spinal transection must be sought. A recirculating of the reflex arc distal to the injury could occur on the basis of collateral sprouting of J. Neurosurg. / Volume 40 / January,

6 G. L. Rockswold, W. E. Bradley and S. N. Chou dorsal root axons. 16A7 This concept is supported by De Groat and Ryall's experimental work in cats, s which showed that the latencies of reflex discharges recorded in parasympathetic neurons evoked by stimulation of the pelvic nerve were much shorter following spinal cord transection than those elicited in the intact spinal cord. They concluded that the short latency spinal reflex was probably unimportant in normal micturition but was due to abnormally circulating impulses in a spinal cord isolated from supraspinal input. In light of present knowledge of micturition reflex organization, it is difficult to interpret the fact that the detrusor reflex can be abolished by unilateral sacral nerve blocks on either the right or left in certain patients. Perhaps there was partial bilateral interruption of the spinal cord pathways of the detrusor reflex by the disease process, and sacral blocks on either side were sufficient to interrupt the detrusor reflex. Sacral nerve blocks are valuable in the evaluation and care of patients with neurological bladder dysfunction. Information accumulated by using air cystometry and urinary sphincter electromyography with sacral nerve blocks will contribute to a better understanding of human bladder physiology. In addition, the effects of these blocks on rectal and sexual function also deserve further study. References 1. Barrington FJF: The localization of the paths subserving micturition in the spinal cord of the cat. Brain 56: , Barrington FJF: The relation of the hindbrain to micturition. Brain 44:23-52, Bors E: Neurogenic bladder. Urol,Survey 7: , Bors E, Comarr AE: Neurological Urology. Baltimore, University Park Press, Bradley W, Clarren S, Shapiro R, et al: Air cystometry. J Urol 100: , Bradley W, Logothetis J, Kennedy W, et al: Electromyography and spinal cord evoked responses in examination of voiding in patients with multiple sclerosis. Neurology 21:397, Bradley WE, Teague CT: Spinal cord organization of micturition reflex afferents. Exp Neurol 22: , de Groat WC, Ryall RW: Reflexes to sacral parasympathetic neurones concerned with micturition in the cat. J Physiol 200:87-108, I Denny-Brown D, Robertson EG: On the physiology of micturition. Brain 56: , Denny-Brown D, Robertson EG: The state of the bladder and its sphincters in complete transverse lesions of the spinal cord and cauda equina. Brain 56: , Fog T" Topographic distribution of plaques in the spinal cord in multiple sclerosis. Arch Neurol Psyehiat 63: , Harmon NB: The pelvic splanchnic nerves; an examination into their range and character. J Anat Lond 33: , Heimburger RF, Freeman LW, Wilde NJ: Sacral nerve innervation of the human bladder. J Neurosurg 5: , Kimmel DL, McCrea LE: The development of the pelvic plexuses and the distribution of the pelvic splanchnic nerves in the human embryo and fetus. J Comp Neurol 110: , Learmonth JR: A contribution to the neurophysiology of the urinary bladder in man. Brain 54: , Liu CN, Chambers WW: Intraspinal sprouting of dorsal root axona; development of new collaterals and preterminals following partial denervation of the spinal cord in the cat. Arch Neurol Psychiat 79:46-61, McCough GP, Austin GM, Liu CN, et al: Sprouting as a cause of spasticity. J Neurophysiol 21: , Meredith JM: The importance of anatomic precision in differential sacral neurotomy for "cord bladder." Am J Surg 87: , Moore DC: Regional Block: A Handbook for Use in the Clinical Practice of Medicine aml Surgery. Springfield, Ill, Charles C Thomas, 1965, ed Nagib A, Leal J, Voris HC: Successful control of selective anterior sacral rhizotomy for treatment of spastic bladder and ureteric reflex in paraplegics. Med Serv $ Canada 22: , Nathan PW, Smith MC: The centrifugal pathway for micturition within the spinal cord. J Neurol Neurosurg Psychiat 21: , Nathan PW, Smith MC: The centripetal pathway from the bladder and urethra within the spinal cord. J Neurol Neurosurg Psychiat 14: , Nesbit RM, McLellan FC: Sympathectomy for the relief of vesical spasm and pain resulting from intractable bladder infection. Surg Gynec Obstet 68: , Rockswold GL, Bradley WE, Chou SN: Differential sacral rhizotomy in the treatment of neurogenic bladder dysfunction: preliminary report of six cases. J Neurosurg 38: , Ruch TC: Central control of the bladder, in 88 I. Neurosurg. / Volume 40 / January, 1974

7 Effect of sacral nerve block on bladder Magoun HW (ed): Handbook of Physiology, Vol 2, Sect 1: Neurophysiology. Baltimore, Williams & Wilkins, 1960, pp Sheehan D: Spinal autonomic outflows in man and monkey. J Comp Neurol 75: , Stewart CC: On the course of impulses to and from the cat's bladder. Am J Physiol 2: , Woollard HH, Norrish RE: The anatomy of the peripheral sympathetic nervous system. Brit J Surg 21:83-103, 1933 This study was supported in part by U. S. Public Health Service Research Grant NS06055 and National Institutes of Health Training Grant NS Address reprint requests to: Shelley N. Chou, M.D., Department of Neurosurgery, Medical School, B-590 Mayo Memorial Building, Minneapolis, Minnesota J. Neurosurg. / Volume 40 / January,