Effects of sacral neuromodulation on isolated urinary bladder function in a rat model of spinal cord injury.

INTRODUCTION: Sacral neuromodulation has been considered as an effective treatment option for various types of chronic voiding dysfunction, but the mechanism of action has not been well understood. The aim of this study was to evaluate the effect of chronic sacral neuromodulation on isolated bladder functions in a rat model of spinal cord injury. MATERIALS AND METHODS: Female Sprague-Dawley rats (250-300 g; N = 20) were assigned to four groups as follows: 1) control group (N = 6); 2) spinal cord transection group (SCT; N = 5); 3) spinal cord transection + sacral neuromodulation group (SCT + SNM; N = 5); 4) sham (spinal cord transection + electrode wire implantation without sacral neuromodulation; N = 4). The rats in the SCT, SCT + SNM, and sham groups were anesthetized with ketamine (60 mg/kg, i.p.) and xylazine (7 mg/kg, i.p.). The spinal cord was completely transected at T8-T9 level in SCT and SCT + SNM groups. Electrode wires were implanted into S3 dorsal foramina in both sham and SNM groups, but only the SNM group was subjected to electrical stimulation for four hours a day for three weeks. Twenty-one days later, the rats were sacrificed via anesthetic overdose, and isolated longitudinal bladder strip preparations were placed in organ baths for the investigation of their isometric responses to pharmacological agents. RESULTS: In isometric contraction experiments, SCT was found to increase the contraction responses of the bladder strips to muscarinic stimulation, and SNM could not prevent this increase. In isometric relaxation experiments, SCT caused a decrease in ß-adrenergic relaxation responses, and SNM augmented the bladder's ß-adrenergic relaxation responses. Nitric oxide did not affect the relaxation responses. CONCLUSION: In our rat model of SCT, SNM seemed to alter adrenergic receptor function in the urinary bladder. Further studies are required to clarify the mechanism of these alterations at the level of bladder receptors following sacral neuromodulation.

Factors affecting the success of ureteroscopy in management of ureteral stone diseases in children.

PURPOSE: We retrospectively investigated the factors that affect the success of rigid ureteroscopy in the pediatric population for the management of pediatric ureteral stones. PATIENTS AND METHODS: We present a retrospective review of 61 consecutive pediatric patients who underwent 66 rigid ureteroscopy procedures for ureteral stone management. The effects of sex, age, stone diameter, stone localization, and degree of associated ureterohydronephrosis (UHN) on the success of ureteroscopy were evaluated. RESULTS: The mean age of the patients was 8.1 years (range 6 mos-16 yrs). The average stone diameter was 8.22 mm (range 4-20 mm). In 56 cases (84.8%), all of the stones were extracted. In five (7.6%) cases, clinically significant residual fragments were detected and extracted by second-look ureteroscopy. In five cases (7.6%), the operations ended in failure. The final stone clearance rate after ureteroscopic stone treatment was higher in lower ureteral stones then in middle and upper ureteral stones; thus, the difference was statistically significant (P = 0.011). Also, there is a significant negative correlation between stone size and success rate (P = 0.007). The final stone clearance rate after ureteroscopic stone treatment was higher in patients with no and mild UHN than in patients with moderate and severe UHN, but the difference was statistically insignificant (P = 0.118). Statistical analyses revealed no significant relationship between success rates with regard to the sex and age of the patients (P = 0.643 for sex, P = 0.390 for age). CONCLUSION: The stone localization and stone size are the factors that affect the success of the procedure.

The effects of hydronephrosis and stone burden on success rates of shockwave lithotripsy in pediatric population.

OBJECTIVES: To evaluate the efficacy of shockwave lithotripsy (SWL) with a third-generation SWL machine in the pediatric age group and to determine the effects of stone burden and the degree of hydronephrosis on the results. METHODS: Two hundred and sixty children with urinary system stones were treated with Siemens Lithostar Modularis Uro-Plus. The patients were divided into three groups according to stone burden (group 1: <100 mm(2); group 2: 101-200 mm(2); group 3: >200 mm(2)) and into four groups according to the degree of hydronephrosis (group 0: absent; group 1: mild; group 2: moderate; group 3: severe). These groups were compared in terms of the success rate of SWL. RESULTS: Two hundred and seventy-nine renoureteral units of 260 patients were treated with 402 SWL sessions. The average stone burden was 98.2 mm(2) (range: 11-525). The overall success rate was 87.5%. According to stone burden, the success rate was 93.1% in group 1, 85.5% in group 2, and 60% in group 3 (p < 0.001). According to the degree of hydronephrosis, the success rate was 93.8% in group 0, 89.6% in group 1, 73.3% in group 2, and 64.3% in group 3 (p < 0.001). The average energy, number of shockwaves, number of sessions, retreatment rate, auxiliary procedure rate, and overall efficacy quotient were 1.76 units, 2260, 1.4, 33%, 8.2%, and 0.62, respectively. CONCLUSION: SWL is an effective treatment method in selected patients in pediatric age group. However, percutaneous nephrolithotomy can be the first alternative for stones larger than 200 mm(2). It should also be kept in mind that the success rate of SWL decreases when the degree of hydronephrosis increases.