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Urodynamic Patterns after Acute Spinal Cord Injury: Association with Bladder Trabeculation in Male Patients
0022-5347 /83/l.294·-0777$02,00/Q 129.
1'HE JOiJRNAL OF UROLOG:l
Printed in
Copyl'ight © 1983 by The 'Nilliams & \1Vilkins Co.
URODYNAMIC PATTERNS AFTER ACUTE SPINAL CORD INJURY: ASSOCIATION Vi/ITH BLADDER TRABECULATION IN MALE PATIENTS RODNEY U. ANDERSON From the Department of Surgery, Division of Urology, Stanford University School of Medicine, Stanford and Institute for Medical Research, Santa Clara Valley Medical Center, San Jose, California
ABSTRACT
A study was done on 80 male acute spinal cord injury patients with reflex bladder voiding to demonstrate an association between the development of radiological bladder trabeculation and serial urodynamic pressure/flow measurements. All patients were evaluated with cystograms and urodynamic studies during l to 3, 4 to 9 and 10 to 24 months after injury. Urodynamic measurements from those patients with bladder trabeculation were compared to those who .retained normal-appearing bladders on x-ray. A high percentage of patients (70 per cent) suffered trabeculation by 24 months after injury. Post-void residual urine volumes were not clinically helpful in identifying those patients with bladder deterioration. However, analysis of the urodynamic pressure/flow measurements revealed significant differences between patients who had trabeculation and those who maintained normal bladders on x-ray during the 3 sequential intervals after injury. Urologic complications and renal insufficiency continue to represent important aspects of the morbidity following spinal cord injury. Longitudinal studies compiled from rehabilitation centers reveal a high incid,:mce of infection, vHuna"""", vesicoureteral reflux and hydronephrosis occurring after injury. 1- 3 A major portion of these complications occur in male patients suffering from poor bladder balance owing to detrusor-sphincter dyssynergia. 3 Effective measures can be taken to prevent the development of bladder deterioration and resultant urinary tract deterioration if poor bladder balance is detected early. Bladder trabeculation is one of the earliest manifestations of neurog,mic dysfunction. The urodynamic features existent in patients with trabeculation of the bladder are characterized herein and compared to those of patients with no evidence of trabeculation. PATIENTS AND METHODS
Included in this series were 80 male spinal cord injury subadmitted to the rehabilitation center within 30 days of OrJy ~wcJ_,~~"~ who had reflex were evaluated but none was continent, Of the patients 28 per cent had,,,_,-,.,,_.,-,,and 72 per- cent had cord lesions. Baseline radiologic studies were obtained when required cervical frames or spinal v-,,~,---"'--'°" surgery, The radiologic consisted of a voiding cystourethrogram and limited excretory including a scout film, and 5 and 20-minute films. cystourethrography vvas done using an 8F pediatric feeding tube. The presence or absence of trabeculation was determined radiologically after at least 200 ml. contrast material had been infused but before any voiding occurred. These radiologic studies were performed l to 3, 4 to 9 and 10 to 24 months after spinal cord injury. Urodynamics. Urodynamic measurements usually were performed the same day as the radiologic studies or l to 2 weeks afterwards in some cases. When > 1 urodynamic study was performed on a patient within a given interval after injury the average of those measurements was computed for analysis. Synchronous water (37C) cystosphincterometry was done
using a medium fill rate of 30 ml. per minute through a 7F urethral membrane catheter as described previously, 4 The bladder volume at the onset of detrusor contraction, maximum premicturition bladder pressure and average intravesical pressure during voiding were measured. Urinary flow was measured to determine volume voided, maximum and average flow rates, opening time (number of seconds from the onset of a detrusor contraction to onset of urinary flow) and post-void residual. Urodynamic measurements in each group were averaged and compared between patients demonstrating radiological trabeculation and those with no evidence of trabeculation within the framework of the 3 observation intervals. Methods, definitions and units conform to the standards proposed by the International Continence Society except when noted specifically. Infection control. Each subject received appropriate antimicrobial therapy for bacteriuria detected at the time of hospitalization. Sterile intermittent catheterization was instituted at 4, 6 or 8-hour intervals to limit maximum bladder filling to <500 mL Patients received oral doses of 100 mg. nitrofurantoin macrocrystals once daily and had post-catheterization instillation of neomycin/polymy-',dn R 5 During the inpatient urme cultures were monitored daily and bacteriuria pers1st,mt for 2 consecutive at a level of > 10,000 1_;v,vune:, per n11. 1Nas antimicrobial. agents. 6 After the patient was from the uv.:,p,c= bacteriuria was monitored every time returned for a urinary tract study. Intermittent catheterization was discontinued as patients achieved a balanced bladder, that is when they were voiding without high bladder pressure and the residual urine volumes were <100 ml. If the urodynamic studies demonstrated either- overactivity of the bladder or evidence of obstruction the patients were treated with combinations of anticholinergics, a-adrenergic blocking agents, skeletal muscle relaxants and surgical incision of the external sphincter in a few instances. Any subjects who underwent an external sphincterotomy were excluded from the longitudinal studies for comparison purposes. Patients receiving pharmacological agents were included in the comparison analysis if they did not require intermittent catheterization.
Accepted for publication August 20, 1982. Read at annual meeting of Western Section, American Urological Association, Coronado, California, February 21-25, 1982. Supported by National Institute of Handicapped Research Grant 13p-59121/9.
RESULTS
Radiologic studies. Voiding cystourethrography showed that early bladder deterioration in the form of trabeculation oc777
778
AN.DERSON
curred within 1 to 3 months after injury in 17 of 74 subjects (23 per cent). Of the subjects with trabeculation 8 had incomplete and 9 complete spinal cord lesions. In addition to the trabeculation 2 of the patients had vesicoureteral reflux and both had sterile urine cultures at the time of the study. No patient had hydroureter or pyelocaliectasis during the first 3 months after injury. Of the remaining 57 patients with normal-appearing bladders on radiological examination 13 had incomplete and 44 had complete lesions. During the 4 to 9-month interval after injury 59 patients were evaluated. The number of patients with bladder trabeculation increased to 54 per cent and by the end of the 24-month observation it had increased to 70 per cent. Also, at 24 months 10 patients (12.5 per cent) had suffered reflux and 4 (5 per cent) had various grades of hydronephrosis. All of these patients with upper tract deterioration had accompanying bladder trabeculation. Urodynamic studies. The results of longitudinal urodynamic measurements during the 3 intervals after injury in patients with and without bladder trabeculation on x-ray are shown in table 1. There was considerable variation in the numbers of measurements evaluable owing to variability in subject performance and some patients failed to return for the followup testing. It can be seen that the volume voided was significantly different (p <0.01) between the 2 groups during the earliest interval, being reduced in the subjects with trabeculation. In fact, during all 3 intervals after injury the healthy bladder group voided larger volumes but it was only statistically significant during the first 3 months. Although the pre-micturition pressure was consistently higher in the bladder trabeculation group, suggestive of obstruction, the values were only significant during the 4 to 9-month interval. A similar pattern was noted for average voiding pressure. The opening time was prolonged in both groups, sometimes up to l½ minutes, in contrast to a 10second opening time seen in neurologically intact patients tested under the same conditions. To evaluate a composite of the urodynamic measurements, average voiding pressure, average flow rate and volume voided were considered. These measurements were analyzed in a ratio of average flow rate X volume voided/average voiding pressure, which provided a single number index. Table 2 shows this micturition index as calculated in the normal bladder group TABLE
1. Urodynamic measurements of subjects with normal and trabeculated bladders during 3 intervals after injury Interval After Injury (mos.)
Bladder volume at onset of detrusor contraction (ml.) Time from detrusor contraction to flow-opening time (sec.) Maximum pre-micturition intravesical pressure (cm. water) Av. flow rate (ml./sec.)
Volume voided (ml.)
Post-void residual volume (ml.)
Av. voiding pressure (cm. water)
1-3 4-9 10-24 1-3 4-9 10-24 1-3 4-9 10-24 1-3 4-9 10-24 1-3 4-9 10-24 1-3 4-9 10-24 1-3 4-9 10-24
Bladder Condition on X-Ray* Normal (No. pts.) 356 ± 335 ± 291 ± 100 ± 121 ± 68 ± 70 ± 72 ± 72 ± 4± 3± 4± 219 ± 171 ± 181 ± 185 ± 186 ± 130 ± 52 ± 50 ± 42 ±
24 28 42 26 39 21 9 8 13 0.6 0.6 0.9 22 21 26 22 22 42 5 7 6
(32) (24) (9) (19) (18) (9) (28) (21) (9) (25) (17) (9) (25) (17) (9) (34) (34) (9) (24) (21) (9)
Trabeculated (No. pts.) 257 ± 207 ± 246 ± 172 ± 82 ± 91 ± 83 ± 128 ± 84 ± 3± 3± 3± 124 ± 140 ± 131 ± 163 ± 106 ± 159 ± 60 ± 70± 59 ±
* Mean ± standard error. t p <0.01 compared to normal group in same interval after injury. :j:p <0.05.
57 24 31 63 20 25 9 13 10 0.5 0.6 0.5 19 22 14 57 19 24 7 9 8
(10) (23)t (23) (14) (21) (18) (14) (21)t (18) (14) (20) (23) (14)t (20) (18) (9) (2l)t (22) (14) (21):j: (18)
TABLE
2. Micturition index in male spinal cord injury patients
Interval After Injury (mos.)
Normal (No. pts.)
Trabeculated (No. pts.)
1-3 4-9 10-24
26.6 ± 7.3 (19) 12.8 ± 3.1 (18) 21.3 ± 7.2 (10)
5.9 ± 1.0 (14)t 4.7 ± 1.0 (19)t 6.9 ± 1.2 (18)t
Bladder Condition on X-Ray*
Micturition index, (Q X V)/P, was calculated from a relationship of average flow rate (Q av.), volume voided (V) and average voiding pressure (Pav.). * Mean ± standard error. t p <0.05 compared to normal group in same interval after injury.
compared to the trabeculated bladder group in the 3 intervals tested. By combining these 3 measurements into a ratio, statistically significant values are found between the 2 groups in every interval (p <0.05). There were 18 subjects who received oral uropharmacologic agents to treat bladder hyperactivity with or without detrusorsphincter dyssynergia. The mean pre-treatment micturition index was calculated to be 8.5 ± 1.8 (standard error) and the post-treatment index increased to 20.8 ± 4.9. This represented a significant improvement (p <0.001) when tested by a paired Student's t test analysis. Infection control. Bacteriuria monitoring at the time of radiologic and urodynamic testing revealed that 9 per cent of the patients with nontrabeculated bladders had significant bacteriuria (> 104 colonies per ml.) at 1 to 3 months compared to 30 per cent in the trabeculated bladder group. By the end of the 2-year observation period 25 per cent of the normal group and 50 per cent of the trabeculated bladder group had infection. DISCUSSION
The prevalent method of urologic management following spinal cord injury includes evaluation with an IVP, urine culture and measurement of post-void residual urine volume. Most physicians are satisfied with a post-void residual volume <100 ml. or 25 per cent of the bladder capacity. The bladder is said to be balanced under these conditions. However, Stover and associates reported that patients whose bladder balance status was defined by residual urine volume measurements and a status free of a catheter suffered pyelocaliectasis 30 per cent of the time within 2 to 6 years after injury. 2 Detrusor-sphincter dyssynergia clearly is the major cause of poor bladder emptying, and McGuire and Brady found that even a sphincterotomy may not prevent upper tract damages. 3 They followed patients for 2 years after injury and demonstrated that sphincterotomy by itself was no panacea for bladder emptying. It appears that lower urinary tract function in the spinal cord injury patient should be monitored carefully with objective urodynamic data and x-ray studies. Clinical voiding patterns and post-void residual urine volumes may be misleading. The concept of balanced bladder following acute spinal cord injury needs better definition. Bladder trabeculation is an early form of deterioration that develops in the face of detrusor instability and outflow obstruction. 7 This trabeculation consists of smooth muscle hypertrophy that progresses with time to total replacement by collagen. 8 The distortion of the bladder wall from hypertrophy and fibrous tissue creates ureterovesical junction changes, which result in obstructive and refluxing physiologic patterns. In this series of patients hydronephrosis and reflux occurred only in those with accompanying bladder trabeculation. While trabeculation has been reported to occur in lower motor neuron bladders, this investigation was concerned only with reflex bladders. In some of these patients early trabeculation (1 to 2+) on an x-ray improved after pharmacological manipulation and improvement of the urinary micturition index. This iµvestigation demonstrates that single urodynamic measurements do not predict which patients might have tra-
URODYNAMIC PATTERNS AFTER ACUTE SPINAL CORD INJURY
beculation of the bladder; post-void residual urine volumes actually were lower in the bladder deterioration group. Virtually all subjects had varying degrees of detrusor-sphincter dyssynergia, with a common finding of prolonged, uninhibited waves of detrusor contraction occurring before opening. Low amplitude detrusor waves also occurred without simultaneous spastic sphincter activity and may represent a response owing to the filling rate of 30 ml. per minute. No correlation with this prolonged detrusor activity and radiologic bladder trabeculation could be found. It is necessary to analyze combinations of urodynamic measurements to quantify the differences between the normal and bladder deterioration groups. Various urodynamic scoring systems have been proposed to measure bladder function and outlet resistance. Mural wall tension, calculated from intravesical pressure, volume and radius of the bladder as a sphere, is an example. 9 Urethral resistance (R) = bladder pressure (P)/flow rate squared (Q 2 ), is a convenient calculation and quite helpful in quantifying degrees of outlet obstruction. 10' 11 However, Abrams and associates found that bladder function must include the volume voided, since it showed no correlation with urethral resistance alone. 12 Abrams and Griffiths reported that prostate obstruction could be assessed objectively from a plot of detrusor pressure against flow rate throughout voiding. 13 Any urodynamic scoring system used in patients after spinal cord injury must take into account the rampant variability in the same individual, even on the same day, and progressive changes in neurophysiologic patterns with time after injury. The advantage of a quantitative index for micturition as proposed in this study lies in its numerical quality. Comparison numbers may alert the physician to poor urethral vesical function. Based upon the results of this investigation a micturition index of 10 is considered to be the lowest acceptable value in a patient who possesses uncontrolled reflex bladder activity. Values below this level suggest vulnerability for bladder deterioration, first in the form of trabeculation and then progression to reflux and hydronephrosis. For comparison purposes neurologically normal male subjects who underwent the same testing in our laboratory have average micturition indexes approaching 100. The index also is valuable in assessing the results of pharmacological manipulation. When a poor micturition index is improved to a value > 10 surgical procedures such as sphincterotomy may be procrastinated. Patients who have poor balance and inadequate detrusor activity frequently are converted to low pressure systems with anticholinergic agents and managed with intermittent catheterization. If pharmacological management is not satisfactory or there is evidence of deterioration, then a sphincterotomy becomes the procedure of choice. More intensive evaluation using frequent objective urodynamic measurements and cystograms should be performed in the early months following spinal cord injury and consequent neurogenic bladder. Bladder management during those crucial weeks may set the stage for a lifetime. Urodynamic studies were performed by Paula Gilman and Glenn Mullin. Clinical coordination was provided by Karen
Ziegler. Dr. Ann Lynch performed the radiological interpretations. REFERENCES
1. Price, M., Kottke, F. J. and Olson, M. E.: Renal function in patients with spinal cord injury: the eighth year of a ten-year continuing study. Arch. Phys. Med. Rehab., 56: 76, 1975. 2. Stover, S. L., Lloyd, L. K., Nepomuceno, C. S. and Gale, L. L.: Intermittent catheterisation: follow-up studies. Paraplegia, 15: 38, 1977. 3. McGuire, E. J. and Brady, S.: Detrusor-sphincter dyssynergia. J. Urol., 121: 774, 1979. 4. Karol, J.B. and Anderson, R. U.: Evaluation of synchronous water cystosphincterometry with the membrane catheter in spinal cord injury. J. Urol., 123: 907, 1980. 5. Anderson, R. U.: Prophylaxis of bacteriuria during intermittent catheterization of the acute neurogenic bladder. J. Urol., 123: 364, 1980. 6. Anderson, R. U. and Hatami-Tehrani, G.: Monitoring for bacteriuria in spinal cord-injured patients on intermittent catheterization. Dip-slide culture technique. Urology, 14: 244, 1979. 7. Shah, P. J. R., Whiteside, C. G., Milroy, E. J. G. and TurnerWarwick, R. T.: Radiological trabeculation of the male bladdera clinical and urodynamic assessment. Brit. J. Urol., 53: 567, 1981. 8. Gosling, J. A. and Dixon, J. S.: Structure of frabeculated detrusor smooth muscle in cases of prostatic hypertrophy. Urol. Int., 35: 351, 1980. 9. Anikwe, R. M.: Bladder wall tension in benign prostatic hypertrophy. Invest. Urol., 14: 452, 1977. 10. Susset, J. G., Rabinovitch, H. H., Rosario, F. and MacKinnon, K. J.: Measurement of urethral resistance. J. Urol., 96: 746, 1966. 11. Anikwe, R. M.: Direct recording of urethral resistance using the "urethroresistance". J. Urol., 119: 643, 1978. 12. Abrams, P. H., Skidmore, R., Poole, A. C. and Follett, D.: The concept and measurement of bladder work. Brit. J. Urol., 49: 133, 1977. 13. Abrams, P. H. and Griffiths, D. J.: The assessment of prostatic obstruction from urodynamic measurements and from residual urine. Brit. J. Urol., 51: 129, 1979. EDITORIAL COMMENT The author has explored the vagaries of spinal cord injury and has arrived at a combination of findings, permitting an over-all plan of management predicted on individual variability. This pragmatic approach is useful and allows a period of delay before one commits patients to a permanent method of management that many early spinal cord injury patients resist hoping for recovery. The reference to McGuire and Brady (reference 3 in article) is not completely accurate. As Doctor Anderson, those authors found that reliance on a concept of "balanced bladder function" determined by residual urine and capacity was inaccurate and dangerous. Indeed, half of the patients believed to show "balanced bladder function" had upper tract changes with time. Edward J. McGuire Department of Surgery Section of Urology Yale University School of Medicine New Haven, Connecticut
1'HE JOiJRNAL OF UROLOG:l
Printed in
Copyl'ight © 1983 by The 'Nilliams & \1Vilkins Co.
URODYNAMIC PATTERNS AFTER ACUTE SPINAL CORD INJURY: ASSOCIATION Vi/ITH BLADDER TRABECULATION IN MALE PATIENTS RODNEY U. ANDERSON From the Department of Surgery, Division of Urology, Stanford University School of Medicine, Stanford and Institute for Medical Research, Santa Clara Valley Medical Center, San Jose, California
ABSTRACT
A study was done on 80 male acute spinal cord injury patients with reflex bladder voiding to demonstrate an association between the development of radiological bladder trabeculation and serial urodynamic pressure/flow measurements. All patients were evaluated with cystograms and urodynamic studies during l to 3, 4 to 9 and 10 to 24 months after injury. Urodynamic measurements from those patients with bladder trabeculation were compared to those who .retained normal-appearing bladders on x-ray. A high percentage of patients (70 per cent) suffered trabeculation by 24 months after injury. Post-void residual urine volumes were not clinically helpful in identifying those patients with bladder deterioration. However, analysis of the urodynamic pressure/flow measurements revealed significant differences between patients who had trabeculation and those who maintained normal bladders on x-ray during the 3 sequential intervals after injury. Urologic complications and renal insufficiency continue to represent important aspects of the morbidity following spinal cord injury. Longitudinal studies compiled from rehabilitation centers reveal a high incid,:mce of infection, vHuna"""", vesicoureteral reflux and hydronephrosis occurring after injury. 1- 3 A major portion of these complications occur in male patients suffering from poor bladder balance owing to detrusor-sphincter dyssynergia. 3 Effective measures can be taken to prevent the development of bladder deterioration and resultant urinary tract deterioration if poor bladder balance is detected early. Bladder trabeculation is one of the earliest manifestations of neurog,mic dysfunction. The urodynamic features existent in patients with trabeculation of the bladder are characterized herein and compared to those of patients with no evidence of trabeculation. PATIENTS AND METHODS
Included in this series were 80 male spinal cord injury subadmitted to the rehabilitation center within 30 days of OrJy ~wcJ_,~~"~ who had reflex were evaluated but none was continent, Of the patients 28 per cent had,,,_,-,.,,_.,-,,and 72 per- cent had cord lesions. Baseline radiologic studies were obtained when required cervical frames or spinal v-,,~,---"'--'°" surgery, The radiologic consisted of a voiding cystourethrogram and limited excretory including a scout film, and 5 and 20-minute films. cystourethrography vvas done using an 8F pediatric feeding tube. The presence or absence of trabeculation was determined radiologically after at least 200 ml. contrast material had been infused but before any voiding occurred. These radiologic studies were performed l to 3, 4 to 9 and 10 to 24 months after spinal cord injury. Urodynamics. Urodynamic measurements usually were performed the same day as the radiologic studies or l to 2 weeks afterwards in some cases. When > 1 urodynamic study was performed on a patient within a given interval after injury the average of those measurements was computed for analysis. Synchronous water (37C) cystosphincterometry was done
using a medium fill rate of 30 ml. per minute through a 7F urethral membrane catheter as described previously, 4 The bladder volume at the onset of detrusor contraction, maximum premicturition bladder pressure and average intravesical pressure during voiding were measured. Urinary flow was measured to determine volume voided, maximum and average flow rates, opening time (number of seconds from the onset of a detrusor contraction to onset of urinary flow) and post-void residual. Urodynamic measurements in each group were averaged and compared between patients demonstrating radiological trabeculation and those with no evidence of trabeculation within the framework of the 3 observation intervals. Methods, definitions and units conform to the standards proposed by the International Continence Society except when noted specifically. Infection control. Each subject received appropriate antimicrobial therapy for bacteriuria detected at the time of hospitalization. Sterile intermittent catheterization was instituted at 4, 6 or 8-hour intervals to limit maximum bladder filling to <500 mL Patients received oral doses of 100 mg. nitrofurantoin macrocrystals once daily and had post-catheterization instillation of neomycin/polymy-',dn R 5 During the inpatient urme cultures were monitored daily and bacteriuria pers1st,mt for 2 consecutive at a level of > 10,000 1_;v,vune:, per n11. 1Nas antimicrobial. agents. 6 After the patient was from the uv.:,p,c= bacteriuria was monitored every time returned for a urinary tract study. Intermittent catheterization was discontinued as patients achieved a balanced bladder, that is when they were voiding without high bladder pressure and the residual urine volumes were <100 ml. If the urodynamic studies demonstrated either- overactivity of the bladder or evidence of obstruction the patients were treated with combinations of anticholinergics, a-adrenergic blocking agents, skeletal muscle relaxants and surgical incision of the external sphincter in a few instances. Any subjects who underwent an external sphincterotomy were excluded from the longitudinal studies for comparison purposes. Patients receiving pharmacological agents were included in the comparison analysis if they did not require intermittent catheterization.
Accepted for publication August 20, 1982. Read at annual meeting of Western Section, American Urological Association, Coronado, California, February 21-25, 1982. Supported by National Institute of Handicapped Research Grant 13p-59121/9.
RESULTS
Radiologic studies. Voiding cystourethrography showed that early bladder deterioration in the form of trabeculation oc777
778
AN.DERSON
curred within 1 to 3 months after injury in 17 of 74 subjects (23 per cent). Of the subjects with trabeculation 8 had incomplete and 9 complete spinal cord lesions. In addition to the trabeculation 2 of the patients had vesicoureteral reflux and both had sterile urine cultures at the time of the study. No patient had hydroureter or pyelocaliectasis during the first 3 months after injury. Of the remaining 57 patients with normal-appearing bladders on radiological examination 13 had incomplete and 44 had complete lesions. During the 4 to 9-month interval after injury 59 patients were evaluated. The number of patients with bladder trabeculation increased to 54 per cent and by the end of the 24-month observation it had increased to 70 per cent. Also, at 24 months 10 patients (12.5 per cent) had suffered reflux and 4 (5 per cent) had various grades of hydronephrosis. All of these patients with upper tract deterioration had accompanying bladder trabeculation. Urodynamic studies. The results of longitudinal urodynamic measurements during the 3 intervals after injury in patients with and without bladder trabeculation on x-ray are shown in table 1. There was considerable variation in the numbers of measurements evaluable owing to variability in subject performance and some patients failed to return for the followup testing. It can be seen that the volume voided was significantly different (p <0.01) between the 2 groups during the earliest interval, being reduced in the subjects with trabeculation. In fact, during all 3 intervals after injury the healthy bladder group voided larger volumes but it was only statistically significant during the first 3 months. Although the pre-micturition pressure was consistently higher in the bladder trabeculation group, suggestive of obstruction, the values were only significant during the 4 to 9-month interval. A similar pattern was noted for average voiding pressure. The opening time was prolonged in both groups, sometimes up to l½ minutes, in contrast to a 10second opening time seen in neurologically intact patients tested under the same conditions. To evaluate a composite of the urodynamic measurements, average voiding pressure, average flow rate and volume voided were considered. These measurements were analyzed in a ratio of average flow rate X volume voided/average voiding pressure, which provided a single number index. Table 2 shows this micturition index as calculated in the normal bladder group TABLE
1. Urodynamic measurements of subjects with normal and trabeculated bladders during 3 intervals after injury Interval After Injury (mos.)
Bladder volume at onset of detrusor contraction (ml.) Time from detrusor contraction to flow-opening time (sec.) Maximum pre-micturition intravesical pressure (cm. water) Av. flow rate (ml./sec.)
Volume voided (ml.)
Post-void residual volume (ml.)
Av. voiding pressure (cm. water)
1-3 4-9 10-24 1-3 4-9 10-24 1-3 4-9 10-24 1-3 4-9 10-24 1-3 4-9 10-24 1-3 4-9 10-24 1-3 4-9 10-24
Bladder Condition on X-Ray* Normal (No. pts.) 356 ± 335 ± 291 ± 100 ± 121 ± 68 ± 70 ± 72 ± 72 ± 4± 3± 4± 219 ± 171 ± 181 ± 185 ± 186 ± 130 ± 52 ± 50 ± 42 ±
24 28 42 26 39 21 9 8 13 0.6 0.6 0.9 22 21 26 22 22 42 5 7 6
(32) (24) (9) (19) (18) (9) (28) (21) (9) (25) (17) (9) (25) (17) (9) (34) (34) (9) (24) (21) (9)
Trabeculated (No. pts.) 257 ± 207 ± 246 ± 172 ± 82 ± 91 ± 83 ± 128 ± 84 ± 3± 3± 3± 124 ± 140 ± 131 ± 163 ± 106 ± 159 ± 60 ± 70± 59 ±
* Mean ± standard error. t p <0.01 compared to normal group in same interval after injury. :j:p <0.05.
57 24 31 63 20 25 9 13 10 0.5 0.6 0.5 19 22 14 57 19 24 7 9 8
(10) (23)t (23) (14) (21) (18) (14) (21)t (18) (14) (20) (23) (14)t (20) (18) (9) (2l)t (22) (14) (21):j: (18)
TABLE
2. Micturition index in male spinal cord injury patients
Interval After Injury (mos.)
Normal (No. pts.)
Trabeculated (No. pts.)
1-3 4-9 10-24
26.6 ± 7.3 (19) 12.8 ± 3.1 (18) 21.3 ± 7.2 (10)
5.9 ± 1.0 (14)t 4.7 ± 1.0 (19)t 6.9 ± 1.2 (18)t
Bladder Condition on X-Ray*
Micturition index, (Q X V)/P, was calculated from a relationship of average flow rate (Q av.), volume voided (V) and average voiding pressure (Pav.). * Mean ± standard error. t p <0.05 compared to normal group in same interval after injury.
compared to the trabeculated bladder group in the 3 intervals tested. By combining these 3 measurements into a ratio, statistically significant values are found between the 2 groups in every interval (p <0.05). There were 18 subjects who received oral uropharmacologic agents to treat bladder hyperactivity with or without detrusorsphincter dyssynergia. The mean pre-treatment micturition index was calculated to be 8.5 ± 1.8 (standard error) and the post-treatment index increased to 20.8 ± 4.9. This represented a significant improvement (p <0.001) when tested by a paired Student's t test analysis. Infection control. Bacteriuria monitoring at the time of radiologic and urodynamic testing revealed that 9 per cent of the patients with nontrabeculated bladders had significant bacteriuria (> 104 colonies per ml.) at 1 to 3 months compared to 30 per cent in the trabeculated bladder group. By the end of the 2-year observation period 25 per cent of the normal group and 50 per cent of the trabeculated bladder group had infection. DISCUSSION
The prevalent method of urologic management following spinal cord injury includes evaluation with an IVP, urine culture and measurement of post-void residual urine volume. Most physicians are satisfied with a post-void residual volume <100 ml. or 25 per cent of the bladder capacity. The bladder is said to be balanced under these conditions. However, Stover and associates reported that patients whose bladder balance status was defined by residual urine volume measurements and a status free of a catheter suffered pyelocaliectasis 30 per cent of the time within 2 to 6 years after injury. 2 Detrusor-sphincter dyssynergia clearly is the major cause of poor bladder emptying, and McGuire and Brady found that even a sphincterotomy may not prevent upper tract damages. 3 They followed patients for 2 years after injury and demonstrated that sphincterotomy by itself was no panacea for bladder emptying. It appears that lower urinary tract function in the spinal cord injury patient should be monitored carefully with objective urodynamic data and x-ray studies. Clinical voiding patterns and post-void residual urine volumes may be misleading. The concept of balanced bladder following acute spinal cord injury needs better definition. Bladder trabeculation is an early form of deterioration that develops in the face of detrusor instability and outflow obstruction. 7 This trabeculation consists of smooth muscle hypertrophy that progresses with time to total replacement by collagen. 8 The distortion of the bladder wall from hypertrophy and fibrous tissue creates ureterovesical junction changes, which result in obstructive and refluxing physiologic patterns. In this series of patients hydronephrosis and reflux occurred only in those with accompanying bladder trabeculation. While trabeculation has been reported to occur in lower motor neuron bladders, this investigation was concerned only with reflex bladders. In some of these patients early trabeculation (1 to 2+) on an x-ray improved after pharmacological manipulation and improvement of the urinary micturition index. This iµvestigation demonstrates that single urodynamic measurements do not predict which patients might have tra-
URODYNAMIC PATTERNS AFTER ACUTE SPINAL CORD INJURY
beculation of the bladder; post-void residual urine volumes actually were lower in the bladder deterioration group. Virtually all subjects had varying degrees of detrusor-sphincter dyssynergia, with a common finding of prolonged, uninhibited waves of detrusor contraction occurring before opening. Low amplitude detrusor waves also occurred without simultaneous spastic sphincter activity and may represent a response owing to the filling rate of 30 ml. per minute. No correlation with this prolonged detrusor activity and radiologic bladder trabeculation could be found. It is necessary to analyze combinations of urodynamic measurements to quantify the differences between the normal and bladder deterioration groups. Various urodynamic scoring systems have been proposed to measure bladder function and outlet resistance. Mural wall tension, calculated from intravesical pressure, volume and radius of the bladder as a sphere, is an example. 9 Urethral resistance (R) = bladder pressure (P)/flow rate squared (Q 2 ), is a convenient calculation and quite helpful in quantifying degrees of outlet obstruction. 10' 11 However, Abrams and associates found that bladder function must include the volume voided, since it showed no correlation with urethral resistance alone. 12 Abrams and Griffiths reported that prostate obstruction could be assessed objectively from a plot of detrusor pressure against flow rate throughout voiding. 13 Any urodynamic scoring system used in patients after spinal cord injury must take into account the rampant variability in the same individual, even on the same day, and progressive changes in neurophysiologic patterns with time after injury. The advantage of a quantitative index for micturition as proposed in this study lies in its numerical quality. Comparison numbers may alert the physician to poor urethral vesical function. Based upon the results of this investigation a micturition index of 10 is considered to be the lowest acceptable value in a patient who possesses uncontrolled reflex bladder activity. Values below this level suggest vulnerability for bladder deterioration, first in the form of trabeculation and then progression to reflux and hydronephrosis. For comparison purposes neurologically normal male subjects who underwent the same testing in our laboratory have average micturition indexes approaching 100. The index also is valuable in assessing the results of pharmacological manipulation. When a poor micturition index is improved to a value > 10 surgical procedures such as sphincterotomy may be procrastinated. Patients who have poor balance and inadequate detrusor activity frequently are converted to low pressure systems with anticholinergic agents and managed with intermittent catheterization. If pharmacological management is not satisfactory or there is evidence of deterioration, then a sphincterotomy becomes the procedure of choice. More intensive evaluation using frequent objective urodynamic measurements and cystograms should be performed in the early months following spinal cord injury and consequent neurogenic bladder. Bladder management during those crucial weeks may set the stage for a lifetime. Urodynamic studies were performed by Paula Gilman and Glenn Mullin. Clinical coordination was provided by Karen
Ziegler. Dr. Ann Lynch performed the radiological interpretations. REFERENCES
1. Price, M., Kottke, F. J. and Olson, M. E.: Renal function in patients with spinal cord injury: the eighth year of a ten-year continuing study. Arch. Phys. Med. Rehab., 56: 76, 1975. 2. Stover, S. L., Lloyd, L. K., Nepomuceno, C. S. and Gale, L. L.: Intermittent catheterisation: follow-up studies. Paraplegia, 15: 38, 1977. 3. McGuire, E. J. and Brady, S.: Detrusor-sphincter dyssynergia. J. Urol., 121: 774, 1979. 4. Karol, J.B. and Anderson, R. U.: Evaluation of synchronous water cystosphincterometry with the membrane catheter in spinal cord injury. J. Urol., 123: 907, 1980. 5. Anderson, R. U.: Prophylaxis of bacteriuria during intermittent catheterization of the acute neurogenic bladder. J. Urol., 123: 364, 1980. 6. Anderson, R. U. and Hatami-Tehrani, G.: Monitoring for bacteriuria in spinal cord-injured patients on intermittent catheterization. Dip-slide culture technique. Urology, 14: 244, 1979. 7. Shah, P. J. R., Whiteside, C. G., Milroy, E. J. G. and TurnerWarwick, R. T.: Radiological trabeculation of the male bladdera clinical and urodynamic assessment. Brit. J. Urol., 53: 567, 1981. 8. Gosling, J. A. and Dixon, J. S.: Structure of frabeculated detrusor smooth muscle in cases of prostatic hypertrophy. Urol. Int., 35: 351, 1980. 9. Anikwe, R. M.: Bladder wall tension in benign prostatic hypertrophy. Invest. Urol., 14: 452, 1977. 10. Susset, J. G., Rabinovitch, H. H., Rosario, F. and MacKinnon, K. J.: Measurement of urethral resistance. J. Urol., 96: 746, 1966. 11. Anikwe, R. M.: Direct recording of urethral resistance using the "urethroresistance". J. Urol., 119: 643, 1978. 12. Abrams, P. H., Skidmore, R., Poole, A. C. and Follett, D.: The concept and measurement of bladder work. Brit. J. Urol., 49: 133, 1977. 13. Abrams, P. H. and Griffiths, D. J.: The assessment of prostatic obstruction from urodynamic measurements and from residual urine. Brit. J. Urol., 51: 129, 1979. EDITORIAL COMMENT The author has explored the vagaries of spinal cord injury and has arrived at a combination of findings, permitting an over-all plan of management predicted on individual variability. This pragmatic approach is useful and allows a period of delay before one commits patients to a permanent method of management that many early spinal cord injury patients resist hoping for recovery. The reference to McGuire and Brady (reference 3 in article) is not completely accurate. As Doctor Anderson, those authors found that reliance on a concept of "balanced bladder function" determined by residual urine and capacity was inaccurate and dangerous. Indeed, half of the patients believed to show "balanced bladder function" had upper tract changes with time. Edward J. McGuire Department of Surgery Section of Urology Yale University School of Medicine New Haven, Connecticut