John S. Wheeler

Percutaneous nephrolithotomy in the spinal cord injury population

We evaluated 23 male spinal cord injury patients who underwent percutaneous nephrolithotomy for the success rate of stone removal and the incidence of operative complications. There were 18 quadriplegic and 5 paraplegic patients, and 5 had bilateral procedures. Of the kidneys 7 had staghorn calculi, 8 had pelvic and caliceal combinations, 6 had large multiple caliceal stones, 4 had large (more than 2.5 cm.) pelvic stones and 3 had pelvic stones less than 2.5 cm. Placement of a nephrostomy tube and stone extraction were performed as a single procedure with the use of general anesthesia in all but 4 patients. Our results showed that 19 of 21 compliant patients (90.4 per cent) were free of stone, with an average of 2.04 procedures per patient. A total of 47 procedures was performed, with an average operative time of 1 hour 45 minutes. Major complications were associated with 4 of the 47 procedures (8.5 per cent), and consisted of a respiratory arrest, 2 perirenal abscesses and a hydrothorax. Minor complications included fever (more than 101.5F) in 64.3 per cent and retained stones in 14.3 per cent of the kidneys operated upon, dislodged nephrostomy tubes in 12.6 per cent of the procedures (21.4 per cent of the kidneys operated upon), and anemia requiring transfusion in 17.0 per cent (8 of 47) of the procedures (27.8 per cent of the kidneys operated upon). The presence of infected stones, prior operative procedures and medical complexity of these patients make complications more frequent. Nevertheless, percutaneous nephrolithotomy is a safe and effective procedure for the spinal cord injury population.

Nephro-Duodenal Fistula: A Complication of Percutaneous Nephrolithotomy

We report a case of a nephro-duodenal fistula complicating percutaneous nephrolithotomy that was managed conservatively. The patient was discharged from the hospital 14 days postoperatively, free of stone and doing well. The etiology and treatment of this problem are discussed.

Botulinum Toxin Injections for Voiding Dysfunction Following SCI

Botulinum toxin (BT) injections have been used successfully to treat spastic muscle conditions, including detrusor-sphincter dyssynergia (DSD) seen in spinal cord injury (SCI) patients. In our urology clinic, we used BT to treat three SCI patients who had voiding dysfunction, using a transperineal needle with electromyographic (EMG) monitoring. Two of the patients reported excellent results following the treatment. One patient, with whom the staff had difficulty doing intermittent catheterization (IC), improved significantly. The other patient had improved voiding with an external catheter and minimal urinary residual. The third patient had no improvement of leg spasms with his voiding dysfunction and required a sphincterotomy. Although patients may need repeat injections, BT is minimally invasive and easy to administer with no side effects. Overall, BT injection is an excellent method of managing voiding in SCI patients, especially those on continuous external catheters and with IC management who refuse or are not good candidates for surgery.

Comparison of direct bladder and sacral nerve stimulation in spinal cats

Neuroprosthetic techniques have been used to facilitate voiding via electrical stimulation for bladder management following spinal cord injury (SCI), but high urethral resistance has been a problem. This problem was investigated here in the chronic, spinal, male cat (C6-T1) using direct bladder and sacral nerve stimulation. Direct bladder stimulation was only conducted during terminal procedures with an open abdomen and with four hook electrodes inserted into the bladder wall. Sacral stimulation was conducted daily during the 10 weeks post-SCI and during terminal procedures. Stimulation was conducted with both implanted epidural electrode and surface electrodes over the sacral bone. Both of these sacral methods stimulated anterior and posterior roots. However, these sacral methods were generally ineffective for inducing voiding during the study. In three of the five animals investigated, stimulation did not empty the bladder. In the remaining two animals, the bladder was emptied with sacral stimulation, but only after return of bladder reflex activity, 2 to 4 weeks post-injury. When poor voiding occurred in spite of high bladder pressures, it indicates high urethral resistance. This was confirmed using video cystourethrography where the membranous urethra was observed to remain closed following stimulation. Direct bladder stimulation was then compared to sacral nerve stimulation during terminal procedures. Direct bladder stimulation induced voiding at a high rate both during and after stimulation, whereas sacral nerve stimulation with implanted electrodes induced voiding at a lower rate and only after stimulation. A simple urethral resistance measure, the ratio of bladder pressure to voiding rate, was lower with direct bladder stimulation than sacral nerve stimulation. Stimulation-facilitated voiding has also been associated with the development of bladder wall hypertrophy. This problem was investigated by evaluating bladder wall thickness postmortem in three groups of animals: the first group was the spinal-stimulated animals detailed above; the additional two groups were a spinal-nonstimulated but instrumented group maintained for 10 weeks following injury, and an intact group of animals. The stimulated spinal cats tended to have the thickest bladder wall followed by the nonstimulated spinal cats. The wall thickness of intact animals served as a control.

Evaluation of direct bladder stimulation with stainless steel woven eye electrodes

Encouraged by recent clinical reports of micturition induced in patients by direct bladder stimulation, we conducted a study of optimum methods of direct bladder stimulation. During surgery six male cats received eight large surface-area woven eye electrodes sutured to the bladder wall serosa, four on the bladder dome and four adjacent to the trigone area. Two additional small surface-area single knot electrodes were sutured in the trigone area. Suprapubic and intraperitoneal tubes were placed for pressure recording and bladder filling. Leg and pelvic floor EMG electrodes were also used for tethered recordings. One to eight weeks after surgery, optimum stimulation methods were evaluated as the animal freely moved about a urodynamic recording cage. Electrodes in the trigone region were more effective than electrodes on the dome and induced bladder contractions and voiding similar to spontaneously induced voiding with bladder filing. Large surface area, woven eye electrodes, composed of multistranded 316LVM stainless steel wire, were more effective than smaller surface area single knot electrodes. High stimulating frequencies (40 Hz) were better than lower frequencies (10 to 20 Hz), and a 1 millisecond pulse duration was optimal. Pulsing with stimulating currents from 10 to 25 mA induced effective bladder contractions with voiding when applied for 3 seconds. However, lower currents using longer stimulation periods were also effective. Bipolar electrodes with both electrodes on the bladder wall were superior to monopolar arrangements with the positive ground electrode along the animals back. We concluded that in the able-bodied cat model, bladder contractile activity for micturition can be induced with direct bladder stimulation and with little discomfort. An effective stimulation protocol consists of capacitor-coupled monophasic pulses with large surface area bipolar electrodes in the trigone region. Stimulating parameters of 40 Hz, 1 msec., 10 to 25 mA applied for 3 seconds were optimal. In addition, based on corrosion resistance observations, the electrodes are quite suitable for long-term studies.

Urodynamic evaluation of urethral opening area in females with stress incontinence

Urodynamic evaluation has been helpful in the diagnosis of stress incontinence in female patients. We evaluated two new parameters using standard urodynamic measures that were recorded during micturition. These two parameters were obtained by fitting a classic fluid dynamic equation for flow through short rigid tubes to published data of voiding, videourodynamics. This formula, an area equivalent factor female (AEFf) indicates urethral cross-sectional opening area based on bladder pressure and flow measures. The first parameter, maximal urethral opening or maximal AEFf, was observed at maximal flow, and this value further divided by the detrusor pressure determined the second parameter, the urethral total compliance. A preliminary retrospective study was conducted using detrusor pressure and urine flow data from stress incontinent (n=14) and continent (n=5) female patients. There was a trend toward greater maximal urethral opening at 14.2±5.9 mm2 in the stress incontinent group compared to the continent group, 9.2±2.9 mm2 (p=0.09). The stress incontinent group also showed a strong trend (p=0.09) toward greater total compliance values of 0.78±0.5 mm2/ cmH2O, compared to 0.35±0.2 mm2/cmH2O in the continent group. These parameters may have potential in the evaluation and understanding of stress incontinence.

Nocardia Epididymo-Orchitis in an Immunosuppressed Patient

The immunocompromised patient after organ transplantation is susceptible to unusual and life-threatening infections. We report a case of epididymitis that evolved into testicular nocardiosis after cardiac transplantation. An awareness of the potential for these infections and early diagnosis may prevent extensive morbidity in the post-transplantation patient.

Bladder-wall and pelvic-plexus stimulation with model microstimulators: Preliminary observations

Severe urinary retention is not a common condition, but may occur following some pelvic surgeries or other medical conditions. Electrical stimulation of the bladder has been examined as a means of managing this difficult problem. We conducted preliminary investigations in cats to prove the hypothesis that pelvic-plexus (bladder-neck) stimulation would produce greater micturition response with reduced side effects, such as animal movement or discomfort, than bladder-wall stimulation with electrodes implanted higher on the bladder wall. We used model microstimulators that mimic the look and function of commercial microstimulators, but that we constructed. We instrumented four female cats during a survival surgery. Animals recovered well and studies were conducted over a 1-month period in the conscious animal and under anesthesia. We performed a variety of studies with different stimulation parameters and electrode locations to evaluate our hypothesis. In the active animal, we supplied only low currents, but two animals responded to stimulation with bladder contractions and voiding. Following anesthesia, higher stimulating currents resulted in greater bladder contractions during stimulation in two of the three animals. In two cases, pelvic-plexus (bladder-neck) stimulation induced greater micturition responses than direct bladder-wall stimulation. In conclusion, we learned from these preliminary observations that stimulation at the pelvic plexus (bladder neck) may induce a better micturition response than stimulation higher on the bladder-wall. Newly available commercial microstimulators should be further studied for the treatment of urinary retention.

Osteomyelitis of the Pubis: Complication of a Stamey Urethropexy

Osteomyelitis pubis is a rare pyogenic infection of the anterior pelvis. Prior pelvic surgery is the factor that usually causes this problem. To my knowledge endoscopic urethropexy, that is the Stamey procedure, has not been reported as a predisposing cause. A case of pubic osteomyelitis following a Stamey urethropexy is reported.

Surface stimulation techniques for bladder management in the spinal dog.

Electrical stimulation of the bladder wall or sacral nerves may be effective for bladder management in the spinal cord injured patient. However, extensive surgery has been required for electrode implantation. We compared urodynamic responses using surface and minimally invasive epidural stimulating techniques in the chronic spinal male dog. Various surface stimulating techniques were effective: 1) sacral monopolar electrical stimulation with negative electrodes over S2 sacral foramina and positive electrodes on the legs, 2) sacral bipolar electrical stimulation with electrodes only over sacral foramina, 3) perineal monopolar electrical stimulation, and 4) perineal tactile stimulation. Urodynamic responses were similar to those for sacral epidural electrodes implanted adjacent to sacral nerves. Voiding was obtained both during stimulation and poststimulation. Stimulating parameters that were effective for daily voiding with sacral surface electrodes were 10 pps, 30 to 45 ma, 0.6 ms pulse duration, and 2 to 5 sec stimulation train duration.