Abstract
Background and Purpose:
Patients with spinal neuropathy are at an increased risk for urolithiasis. Data on percutaneous nephrolithotomy (PCNL) in this population are limited. Our objective is to review our experience in managing stones with PCNL in patients with spinal neuropathy.
Patients and Methods:
Twenty-one patients with spinal neuropathy underwent PCNL at our institution between January 2005 and August 2011. Their medical records were reviewed retrospectively to collect data relating to stone characteristics, treatment outcomes, and complications.
Results:
Forty-two PCNL were performed on 26 kidneys. Five patients had bilateral stones. They were 14 (66.7%) patients with spinal cord injury, 5 (23.8%) with spina bifida, and 2 (9.5%) with other neurologic abnormalities. There were 90.5% of patients with preoperative bacteriuria and 47.6% with severe scoliosis, making positioning for PCNL challenging. Complete staghorn stones occurred in 46.2% of kidneys, and 50% of stones were struvite. Only 53.8% of kidneys were stone free after the first PCNL. The success rate increased to 80.8% after the second and 88.5% after the third PCNL. Urosepsis developed in three (14.3%) patients, necessitating admission to the intensive care unit postoperatively. Six (28.6%) patients needed blood transfusion. One patient had a pneumothorax and another had a perforation of the collecting system.
Conclusions:
Based on our experience, PCNL in patients with spinal neuropathy had a stone clearance rate comparable with that of the general population. These patients, however, needed multiple PCNLs to be stone free and had a higher incidence of complications (especially infectious).
Introduction
The first percutaneous nephrolithotomy (PCNL)was performed in Sweden in 1973. 5 Since then, PCNL has replaced open surgery for the treatment of patients with large and complex renal stones. Because of the complexity of the patients with spinal neuropathy, available literature suggests that PCNL in this population is technically more difficult and associated with increased complications than the general population. 6 –8 Data on PCNL in this patient population is limited, however. 8 The objective of our study is to review our experience in treating patients who have spinal neuropathy with PCNL to determine the technical challenges, results, and complications of this procedure in this special population.
Patients and Methods
A retrospective chart review of patients with spinal neuropathy who underwent PCNL was undertaken. The charts of 21 patients (13 males, 8 females) with spinal neuropathy who underwent PCNL at our institution between January 2005 and August 2011 were reviewed. The review was exempt from Institutional Review Board approval. The procedures were all performed at the Oklahoma University Health Sciences Center by three different surgeons. The patients' medical records were also evaluated to retrieve data relating to patient characteristics, such as age, management of neurogenic bladder, preoperative conditions, and neuropathic condition.
The radiologic records were also reviewed to determine the preoperative and postoperative stone characteristics. Stone size was determined by measuring the greatest length of the stone on CT. In case of a kidney with multiple stones (not including kidneys with complete staghorn), the stone burden of that kidney was determined by adding the sizes of all the stones. Patients also had a functional study (CT urography, intravenous pyelography, or nuclear renography) to assess renal function.
A urine culture was obtained preoperatively in all patients. If patients had bacteriuria, they were treated with a culture-specific oral antibiotic for at least 1 week before the procedure. They were then admitted 1 day before surgery, and broad-spectrum antibiotics were administered intravenously.
Surgical technique
In the majority of cases, the urologist obtained access to the kidney. Under general anesthesia, with the patient in the lithotomy position, a 5F ureteral catheter was advanced to the renal pelvis. The catheter was then secured to a 20F Silastic Foley catheter. The patient was then placed in the prone position. Chest rolls were used to allow adequate ventilation, and all pressure points were appropriately padded. Using biplanar fluoroscopic guidance at 0 and 30 degrees and with an assistant filling the collecting system with contrast through the ureteral catheter, an 18-gauge needle was used to puncture the collecting system. We preferred to puncture the lower and most posterior calix, but depending on the stone location, renal anatomy, and patient spinal deformity, another puncture site may have been chosen.
Two guidewires (a safety and a working wire) were then passed to the bladder. One of the wires was used to dilate the tract using Amplatz dilators or balloon dilation while the other was used as a safety wire. The percutaneous tract was dilated up to 28F or 30F; the access sheath was then placed. Nephroscopy was performed using a 26F rigid nephroscope.
An ultrasonic lithotripter was used to fragment the stones. To access stones in calices with difficult angles, we used a flexible cystoscope with a holmium laser. In the majority of cases, a flexible ureteroscope was also used to clear the ureter from any fragments that migrated from the kidney.
At the end of the procedure, a 20F or 24F reentry nephrostomy tube was placed. In all patients, postoperative chest radiography was obtained. All patients were evaluated on postoperative day 1 with a noncontrast CT scan. Success was defined by complete absence of stones or presence of insignificant fragments (<2 mm), necessitating no further treatment. If patients were stone free, the nephrostomy tube was taken out. If there were residual stones, the reentry tube was kept in place for the second procedure. In case of a second-look PCNL, it facilitated the placement of an antegrade wire. The second procedure was scheduled within 1 week of the first PCNL.
Besides stone-free rate, other study end points were the number of PCNL necessary to clear the stone and intraoperative and postoperative complications (up to 30 days postoperatively).
Results
There were 21 patients who underwent a total of 42 procedures. Five patients had bilateral stones. Overall, these procedures were performed on 26 renal units using the methodology described. There were 13 males and 8 females in our patient cohort. The mean age of our patient population was 38.8 years.
Neurologic conditions of our patients were mainly traumatic spinal cord injuries and spina bifida. They were 14 patients with spinal cord injury (66.7%), and seven (33.3%) had spina bifida. Management of neurogenic bladder in these patients was either with indwelling catheterization (11 patients, 52.4 %), clean intermittent catheterization (8 patients, 38.1%), or urinary diversion with ileal conduit (2 patients, 9.5%). Almost half of our patients (42.8%) had a previous PCNL for kidney stones. The majority (90.5%) had bacteriuria preoperatively. Moreover, 10 (46.2%) patients had severe scoliosis.
Of the 26 kidneys that underwent PCNL, 8 (30.8%) had complete staghorn, 9 (32.6%) had multiple stones (32.6%), and 9 had only one stone (32.6%). The average size of the stones excluding complete staghorns was 31.3 mm. Stone composition mainly consisted of struvite (13/26 kidneys). These stone statistics, including in addition to stone location, are seen in Table 1.
Stone clearance rates increased with the number of PCNL procedures performed. After the first PCNL, 53.8% of kidneys were stone free. Stone clearance rates increased to 80.8% after the second procedure and 88.5% after the third PCNL. Each patient, on average, underwent two PCNL procedures with each renal unit undergoing 1.6 procedures. Complications of the procedures included the admission of three (14.3%) patients to the intensive care unit as a result of urosepsis. Six (28.6%) patients had hemorrhage that necessitated blood transfusion. One patient had a pneumothorax, which resulted in a pleural effusion that was managed conservatively. Another patient had a perforation of the renal collecting system, which was also managed conservatively. There were no mortalities in our patient population. The PCNL data and complication rates are summarized in Table 2.
PCNL=percutaneous nephrolithotomy.
Discussion
Despite major improvement in the urologic treatment of patients with spinal cord injury and neurogenic bladder, the incidence of upper-tract urolithiasis in this population remained stable. 1,9 The etiology of stones in the spinal neuropathy population is multifactorial. During the early stages, immobilization hypercalciuria is thought to play a major role. 10 Later, several factors are believed to play a role, including chronic infection, vesicoureteral reflux, and chronic catheterization. 2 –4 Upper-tract urolithiasis in the spinal neuropathy population is associated with renal function deterioration. Thus, many authors recommend aggressive screening for upper-tract stones in this population with yearly imaging (renal ultrasonography or radiography of the kidneys, ureters, and bladder). 11,12
Extracorporeal shockwave lithotripsy (SWL) is a safe modality of treatment and with good outcomes, especially for stones smaller than <1.5 cm. SWL in patients with spinal neuropathy, however, is associated with poorer rates of stone clearance than the general population. 13,14 This might be because of difficulty in positioning and maintaining the stone within the SWL focal point because of severe spinal deformities, and the lower rate of small fragments passage because of the abnormal anatomy and immobility. In addition, because of their atypical symptoms, 15 many of these patients will already have a large stone burden at the time of diagnosis. making PCNL the procedure of choice.
Current literature on PCNL in patients with spinal neuropathy is limited. 15 In one of the oldest series, Culkin and colleagues 6 reported a success rate of 90% with an average of 2.04 procedure per patient. The same authors, in a later study, 7 reported a lower stone clearance rate in patients with spinal cord injury when compared with the ambulatory population (88.6% vs 98.5%). In more recent studies, the highest success rate reported was 96%. 16 In this series, 16 however, all patients underwent a second-look procedure, four had a third-look procedure, and two had a fourth-look procedure to achieve stone clearance.
In our series, only 53.8% of patients were stone free after the first PCNL, which is comparable to the rate reported in a recent series by Symons and associates 8 (62%). At our institution, treatment of upper urinary lithiasis in patients with spinal neuropathies had an overall success rate of 88.5% with an average of two procedures per patient. These results are compatible with other published series 6 –8,14,16 that showed that in patients with spinal neuropathy, stone-free rates of around 90% can be achieved.
Nevertheless, multiple procedures are often needed to achieve these results. Of note, 30.8% of the kidneys in our series had complete staghorn, and the average size of stone burden in the other kidneys was 31.3 mm. This finding is proof of the significant stone burden often encountered in the patient with spinal neuropathy, which makes PCNL in this special population more challenging. We think that to achieve the results reported above, the urologist should have access to a variety of scopes and instruments (flexible cystoscope, flexible ureteroscope, holmium laser) to overcome the technical challenges encountered in these patients.
Complications rates in the patients with spinal neuropathy who are treated with PCNL are generally higher than in the general population. The higher rate of complications in the spinal neuropathy population is expected because these patients generally have complex medical problems, including limited pulmonary capacity and prolonged immobilization, making the anesthetic requirements more complicated than in the general population. Culkin and coworkers 7 reported a 20% rate of major complications in the patients with spinal cord injury vs 1.4% in the ambulatory patients. Other series report a major complications rates ranging from 7% to 12%. 6,8,16,17
The most common major complications reported are urosepsis, pneumothorax, perirenal abscess, and respiratory arrest. Three deaths are reported in the literature. 7,8 No standard classification was used in reporting the complications, however, which makes comparison between the series difficult.
We report a major complication rate of 14.3% (3/21): Urosepsis developed in three of our patients, and severe hemorrhage necessitating admission to the intensive care unit postoperatively, broad-spectrum antibiotic therapy, and aggressive fluid resuscitation. Of note: All of these patients had positive preoperative urine culture results and were treated with culture-specific antibiotics before the procedure. There was no mortality.
The transfusion rate in our series was 28.6%, which is increased compared with that of other authors. 16,17 The higher risk of hemorrhage encountered in the spinal neuropathy population might be related to the chronic urinary tract infection in this population causing chronic inflammation, which could lead to coagulopathies. 18
Another important factor is the high rate of preoperative bacteriuria in patients with neurogenic bladder. 13,16 In our series, the preoperative urine culture was positive in 90.5% of patients. This finding underlines the importance of obtaining a preoperative urine culture in patients with spinal neuropathy and the need to treat them with a culture-specific antibiotic before the procedure. Our practice is to treat the patients at least for 1 week with a culture-specific oral antibiotic and to admit them 1 day before surgery for intravenous administration of a broad-spectrum antibiotic. We think that this might decrease the rate of sepsis postoperatively, although we did not randomize our patient population to verify this conclusion.
In addition, when pyonephrosis is noted on obtaining access to the kidney, we prefer to reschedule the procedure to allow appropriate drainage of the kidney before attempting to clear the stone. In this series, this was encountered in one patient, which led to immediate termination of the procedure.
One limitation of our study is that we did not perform routine stone cultures, which could have been useful in managing postoperative urosepsis. Another interesting finding in our series is that 47.6% of patients had severe scoliosis, making the positioning for PCNL more challenging and the surgery technically more difficult (Fig. 1). In addition, these patients often have contractured or folded limbs and orthopedic hardware that often prevent good visualization of the kidney with fluoroscopy. This can also explain the higher complication rate in patients with spinal neuropathy when compared with the general population.
Patient with severe scoliosis and bilateral kidney stones.
Limitations of this study include the small number of patients and the lack of standardization in stone classification and in reporting complications. Despite the presence of several studies reporting good outcomes of PCNL in the spinal neuropathy population, we think that more studies using standardized classification systems are needed to report on complications in this complex population. This would allow us to implement prevention measures to decrease the high morbidity associated with PCNL in this population.
Conclusions
PCNL in patients with spinal neuropathies is associated with good outcomes. Multiple procedures are often needed, however, to clear the stones, and the complication rate, especially infectious, is significantly higher than in the general population. These patients often have multiple medical problems, significant stone burden, and abnormal anatomy, making the surgery and the postoperative management more difficult. PCNL is a good option for the management of upper-tract stones in patients with spinal neuropathy, but it requires careful preoperative planning, good equipment, and experienced surgeons.
Footnotes
Disclosure Statement
No competing financial interests exist.