| Purpose When normal function of the lower urinary tract is disturbed among patients with spinal cord injury (SCI), a series of disorder develops in the form of urinary retention, detrusor hyperreflexia, detrusor-sphincter dyssynergia, high bladder pressure, incontinence, poor urine evacuation, ect, so that a number of complications such as vesicoureteral reflux and hydronephrosis. urinary tract infections, renal function failure are regularly found. Other symptoms include hypertension, strong headache, dripping with sweat, reflex bradycardia, which not only make patients suffer, but also threaten their lives. Nowadays we treated it by cystostomy, catherteriazation and transurethral sphincterotomy etc as usual in China. But electric stimulation has been using to treat it since 1970 in the world and became more and more mature. So the first aim of the experiment is to verify the ways of bladder contraction caused by sacral root electric stimulation, and find out the exact sacral root to stimulate and the parameter of electric stimulation.. Because sacral root consists of large diameter myelinated somatic fibers innervating the legs waist, tail (animal) and urethral sphincter(via pudendal nerves) and small diameter myelinated preganglionic parasympathetic fibers innervating detrusor muscle(via pelvic nerve), the major drawback of sacral root stimulation is the simultaneous contraction of all these muscles. Hence, sacral root stimulation leads to detrusor sphincter dyssynergia with the risk of elevated bladderpressure and incomplete bladder emptying. The second aim is to use andol blockage technic to selective activation of the bladder detrusor without activation of the urethral sphincter by selective stimulation of sacral roots.Materials and methods Twelve mongrel dogs. Half male and half female which body weight 10.25~32.3kg. NIHON KOHDFN Stimulator SEN-7101, Polygraph System and Oscillograph made in Japan; Electric monitoring meter made in China, Tianjin; Tripolar and bipolar stannus foil cuff electrodes. Stainless steel bipolar and Tripolar hook electrodes self made .A device of monitoring pressure was self made. Several 4 and 7F catheters.Anaesthesia was induced with pentobarbital (30mg/kg ) intrabdominal cavity Through a small abdominal incision , a 4F catheter was placed to record the pressure changes within the abdominal cavity in part of dogs. A 4F catheter was inserted urethra to measure pressure of urethra, a 7F catheter was inserted via the urethra to measure pressure in the bladder. Laminectomy was performed from T10_n and from L7~S4 and the sacral roots was divided. Practice of stimulation different pairs of sacral roots in different parameter and different electrode. Electric monitoring meter was monitoring current, oscillograph reveal electric wave, Polygraph System was recording the pressure wave, the monitoring pressure device show the pressure of bladder -, urethra and abdominal cavity.Result 11 of 12 dogs responsed well to stimulation. Test stimulation of the S,S2S3root showed the high rise in detrusor pressure with simultaneous contraction of the urethral sphincter. Most of L7 have little relax sphincter function. Totally S4 have rarely effect to detrusor and sphincter by stimulation.with suprathreshold current in certain rang ,the pressure of bladder and urethral become high as current strength become strong, and vice versa. Cuff electrode can decrease current strength, made amplitude more precision. Tripolar can selective activation of the bladder detrusor without activation of the urethral sphincter by selective stimulation of sacral roots.Conclusions1. Common stimulating sacral root can cause simultaneous contract of detrusor and sphincter .The best parameter of bipolar hook electrode: duration 210us, frequency 25Hz, amplitude0.1~6mA. The best parameter of bipolar cuff electrode: duration 210us, frequency 25Hz, amplitudeO.02~l.5mA. simultaneous contract of detrusor and sphincter, pressure of sphincter is higher than detrusor' s, all that made voiding...
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