Electrical stimulation of the rectal ampulla causing reflex voiding

Functional Evaluation of the Rectal Ampulla with Ampullometrogram

An ampullometrogram (AMG) was done in 20 patients to evaluate the rectal ampulla as a functional unit. Results were compared to a cystometrogram (CMG). The AMG displayed a normal curve (capacity 230 to 330 ml; pressure 47 to 80 cmH2O) in 14 of 16 patients having a normal CMG. The AMG was hyporeflexic (variable capacity; no increase in pressure at capacity) in 3 of 5 patients having a hyporeflexic CMG and hyperreflexic (capacity less than 175 ml, pressure over 80 cmH2O) in one patient having a hyperreflexic CMG. This technique might represent a useful clinical adjunct in the evaluation of bladder dysfunction, the evaluation of neurogenic type bowel dysfunction, and in the possible use of functional electrical stimulation for treatment of faecal incontinence or constipation.

Simultaneous dynamic electromyographic proctography and cystometrography

The rectum and bladder share a common origin and work in harmony; disturbance in one may lead to a similar problem in the other. The two have, however, not previously been investigated dynamically and simultaneously. A new system has been devised allowing dynamic integrated electromyographic proctography to be performed simultaneously with cystometrography in 41 patients (28 women and 13 men). Of 16 women with chronic constipation who underwent the combined study, ten were shown to have obstructed micturition. Eight of these ten women exhibited an inappropriate contraction of the puborectalis muscle during micturition, compared with one of the six with normal micturition (P = 0.02). Of the patients with obstructed micturition, seven of eight women with a rectocele also had anismus, compared with none of four women with a rectocele among those who were able to micturate normally (P = 0.02). Eight of the ten women with obstructed micturition thus had a proctological abnormality that explained the urological symptoms. Of 12 women with idiopathic faecal incontinence who underwent the combined study, eight were shown to have genuine stress incontinence of urine. In seven of these the severity was shown to be of type 2a or greater, indicating that pelvic floor dysfunction may be the causal factor of both rectal and urinary symptoms. The combined study shows abnormalities in one system that could explain similar symptoms in the other.

The organization of pudendal motoneurons and primary afferent projections in the spinal cord of the rhesus monkey revealed by horseradish peroxidase

The horseradish peroxidase tracing technique was utilized to study the distribution of motoneurons and primary afferent neurons contributing fibers to the pudendal nerve in the monkey. Application of horseradish peroxidase to the central cut end of the pudendal nerve labeled motoneurons in the ipsilateral spinal cord primarily in the S1 and L7 segments. In transverse sections these neurons were distributed within an oval area (Onuf's nucleus) with an average dimension of 360 X 290 micron, located at the base of the ventral horn, medial to the lateral motor nuclei. An average of 418 (range: 170-577) medium-sized (44 X 26 micron) neurons were labeled per animal. In longitudinal sections the nucleus appeared as a beaded column of cells extending 9.3 mm rostrocaudally with a prominent network of longitudinal dendrites. In the transverse plane, other groups of dendrites were observed: one group extended dorsomedially toward the central canal, while a second group extended dorsolaterally to the intermediolateral gray, with some of the latter dendritic processes following the lateral border of the ventral horn. An average of 9,200 afferent neurons were labeled in the dorsal root ganglia of each animal. Approximately 85% of these cells were located in a single dorsal root ganglion (S1 or S2). This ganglion was always located one spinal segment caudal to the segment containing the majority of cells in Onuf's nucleus. In the spinal cord, afferent labeling in the dorsal columns and Lissauer's tract extended from S3 to at least L1. The density of afferent labeling in the spinal cord paralleled the number of labeled dorsal root ganglion cells in the corresponding segments. From Lissauer's tract and the dorsal columns a prominent collateral fiber bundle passed medially over the apex of the dorsal horn to the dorsal commissure and to medial laminae I-IV of the dorsal horn. A much less prominent pathway passed ventrally along the lateral edge of the dorsal horn to lamina V, where a few collaterals continued medially to the dorsal commissure. The majority of labeled lateral afferent axons ended slightly dorsal to the sacral parasympathetic nucleus. A comparison of the present findings with previous descriptions of the sacral visceral pathways shows a considerable overlap in certain areas of the spinal cord of pudendal and pelvic nerve afferent and efferent systems. This close anatomic relationship is consistent with the physiological observation that somatovisceral integration in the lumbosacral spinal cord is essential for the normal regulation of micturition, defecation, and sexual function.

Another aspect of acute urinary retention in young patients

Four homosexual men and one heterosexual woman presented with acute urinary retention secondary to intense anal intercourse. All had normal urologic histories. Their residual urine volumes ranged from 475 ml to 1,400 ml. Urinalyses and urine cultures were negative. All were treated with an indwelling Foley catheter and then with bethanechol and dibenzyline. Normal micturition was restored. To evaluate the influence of anal dilatation on detrusor function, five control patients with urge incontinence were studied. A cystometrogram (CMG) displayed a hyperreflexic bladder pattern in all five patients. Average bladder capacity was 86 ml. Calibrated anal dilatation increased bladder capacity to the average value of 406 ml on CMG. The diameter of anal dilatation ranged from 3.5 cm to 5 cm. Intense anal intercourse producing severe anal dilatation triggers reflex bladder inhibition leading to acute urinary retention. The sensory input travels from the dilated anus to the sacral spinal micturition center, which sends inhibitory stimuli to the urinary bladder.

Detrusor hyperreflexia inhibited by anal dilatation

Urge incontinence in 6 patients was found to be due to detrusor hyperreflexia. A cystometrogram was repeated during calibrated anal dilatation and showed increased bladder capacity and decreased hyperreflexia in 4 patients and a normal curve in 2 patients. The mechanism of this response is discussed.

Comparison of pressure measurements in the lower urinary and lower fecal pathways

The bladder and rectal ampullae have similar but not identical innervation from the spinal cord S2 to S4. A comparison of the functional behavior of the bladder and rectal ampullae was done with a cystometrogram and an ampullometrogram. The behavior of the urethral and anal sphincters was compared with electromyography and pressure profiles. In 20 patients there was a close relationship between the functional behavior of the lower urinary and lower fecal pathways.

Acute urinary retention in young homosexuals

Acute urinary retention secondary to and intercourse was found in 4 homosexuals. All four were treated initially with an indwelling Foley catheter and then with bethanechol and phenoxybenzamine (Dibenzyline). Normal micturition was restored in all 4 patients. Anal dilatation can produce reflex bladder inhibition resulting in acute retention.