THE INVESTIGATION OF VOIDING MECHANISM IN CHILDREN

The 4th Report: Urodynamic Studies of Neurogenic Bladder in Children

Abstract

The present study was performed on a total of 121 children with neurogenic bladdder, consisting of 51 boys and 70 girls, or diagnostically of 45 with uninhibited neurogenic bladder, 6 with automatic neurogenic bladder and 60 with autonomous neurogenic bladder (incluidng 25 with tethered cord syndrome (Table 1). On these 121 children was performed the voiding urodynamic examination (hereafter referred to as VUD) which simultaneously recorded the voiding factors on a 6-channel polygraph: intra-abdominal pressure, urethral pressure, vesical pressure, tone of the anal sphincter, EMG of the anal sphincter and urinary flow rate. Furthermore, the sacral nerve reflex test using the tone of the anal sphincter and EMG of the anal sphincter was performed as necessary. The Lewis' cystometrograph or the Sato's cystometrograph was used for taking the cystometrogram during filling. The determined values were statistically processed as voiding parameters by the student t-test, with the published values for normal children as standards. The results are presented below.
1. Uninhibited neurogenic bladder
A. From the results of statistic processing of the voiding parameters (Table 2-A), (1) because the resting vesical pressure at the maximal desire to void and the terminal voiding pressure were high and also because the rate of occurrence of vesical after-contraction was high, it was presumed that the bladder was in an unstable state; and (2) urethral resistance during voiding was found located chiefly at the site where the external urethral sphincter is present.
B. From the voiding factor curves, (1) contraction insufficiency or relaxation insufficiency of the pelvic floor musculature during voiding was observed in part of the children (Fig. 1-a-iii), while the voiding factor curves were mostly normal in the other childnren (Fig. 1-b-ii)-A); (2) only a small number of children could not or insufficiently could interrupt voiding voluntarily (Figs. 1-a-i)-B, and 1-b-ii)-C); (3) the urethral pressure was unstable in some children before and after voiding and also during total voiding (Fig. 1-a-i)-B); and (4) the sacral nerve reflex test was normal or enhanced (Fig. 1-a-iii).
2. Automatic neurogenic bladder
A. From the results of statistic processing of voiding parameters (Table 2-A), (1) it was presumed that the bladder and the urethra were in an unstable state as in uninhibitied neurogenic bladder; (2) it was presumed that a very large power was required to open the bladder neck; (3) resistance was found in the external urethral sphincter segment, too; and (4) the urinary flow rate was decreased.
B. From the voiding factor curves, (1) contraction insufficiency of the pelvic floor musculature was found during voiding (Fig. 2-a); (2) the urethral pressure curve was normal or lower than normal, compared with a very high vesical pressure curve (Fig. 2-a); and (3) the sacral nerve reflex test was normal or enhanced (Fig. 2-b).
3. Autonomous neurogenic bladder
Out of the children with this disease, many girls were with hypotonic bladder: therefore, only the girls were divided into those with hypertonic or normotonic bladder and those with hypotonic bladder.
1) Hypertonic or normotonic bladder in boys and girls
A. From the results of statistic processing of the voiding parameters (Table 2-A), (1) there were large losses in energy at the bladder neck; (2) there were some energy losses in the external urethral sphincter segment; (3) the urinary flow rate was low; and (4) many children of this group made the micturition in co-operation with abdominal straining.
B. From the voiding factor curves, (1) children with typical hypertonic or normotonic bladder gave the vesical pressure curve intermixed with sharp spikes due to voiding with abdominal contraction (Figs. 3-a and 3-b); (2) the urethral pressure was low, compared with the markedly high vesical pressure (detrusor-vesical neck dyssynergia); (3) the anal sphincter tone cur