膀胱電気剌激の研究

核下型慢性期脊髄損傷犬について

抄録

Recently, considerable interest has been directed to electrical stimulation of the bladder as a means of management of the incompetent detrusor muscle due to neurogenic dysfunction. Rokujo, one of our colleagues, reported the results of electrical stimulation of the bladder in dogs with upper motor neuron lesion (acute and chronic stages) and also in dogs with acute lower motor neuron lesion. This paper is concerned with the results in dogs with chronic lower motor neuron lesions. 35 female mongrel dogs were subjected to transection of the conus medullaris at the level of the 6-7th lumbar vertebra, and were followed over 5 weeks to 17 months. In dogs with chronic lower motor neuron lesions, the bladder pressure above 40cm. of water could be obtained by using a stimulus of 30 pulses per second, 3 millisecond, and 10-15 volts with a pair of electrodes buried in the detrusor muscle near the uretero-vesical junction, and pressure response remained for 7 months, and then gradually reduced after 8 months.
In most cases, despite a good rise in intravesical pressure, bladder emptying was incomplete mainly because of the urethral contraction encountered in detrusor stimulation. Mechanism of the urethral contraction was analysed by 1) measurement of so called urethral resistence and intraurethral pressure, 2) pick-up of the spread-current, 3) stimulation of urethral muscle, and 4) stimulation of the pudendal nerves. It became apparent that the urethral contraction are due to stimulation of the unsevered pudendal nerves. In many dogs, after bilateral pudendal neurectomy, the bladder could be satisfactorily emptied by electrical stimulation. And in some cases showing poor electrical micturition even after pudendal neurectomy, longitudinal incision of the urethral muscle layer was necessary to produce a good urinary stream. No vesicoureteral reflux was observed.