Long-Term Outcomes of External Sphincterotomy in a Spinal Injured Population

Results 

A total of 84 patients were included in the study (52 with quadriplegia, 32 with paraplegia) undergoing a total of 116 sphincterotomy procedures. Mean followup after the first sphincterotomy was 6.35 years (range 1 to 20). Mean duration between onset of injury to first sphincterotomy was 48 months (median 17, range 2 to 454).

There were 84 first sphincterotomies performed. Mean patient age at first sphincterotomy was 35.6 years. The indications were DSD (73), recurrent UTI (39) and upper tract dilatation (11). Of the 84 primary sphincterotomies 27 required no further intervention (primary success rate 32%). Mean duration of success after this first procedure, including all patients who did not require re-treatment, was 81 months (median 71).

Eventual failure after initial sphincterotomy occurred in 57 of 84 patients (68%). Mean time to failure after 1 procedure was 42.7 months (median 36). The reasons for failure after initial sphincterotomy were UTI (51 cases), DSD (31) and upper tract dilatation (3). These cases were not mutually exclusive.

A second procedure was performed in 30 of the 57 patients in whom primary sphincterotomy failed. The indications were DSD (18), recurrent UTI (10) and upper tract dilatation (2). The procedure was successful without further intervention in 13 of those 30 patients (secondary procedure success rate of 43%). Mean duration of success after a second procedure was 80.2 months (median 68.5). Mean response before failure after a second procedure was 56.1 months (median 50) (see figure).

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Long-term outcome after initial and revision sphincterotomy in study cohort. Asterisk indicates 1 patient went on to undergo third sphincterotomy with durability of 120 months.

A single patient underwent a third procedure with response duration of 120 months, and then after further UTIs also went on to have a fourth procedure with a response duration to date of 72 months. This patient refused all other treatments for almost a decade because of a clinical response to sphincterotomy on each occasion. The degree of DSD was noted to decrease after each procedure as confirmed on videourodynamics. DSD is now absent on videourodynamics and he remains clinically stable.

Although revision sphincterotomy was considered for all patients in whom initial surgery failed, there was a subgroup in whom, over time, there had been additional factors that influenced the decision not to recommend revision surgery, including significant deterioration in general health for reasons unrelated to urinary drainage problems, geographic concerns of coming to a large center for further treatment, patient choice to have an indwelling catheter and patient preference to wait until more than 3 UTIs in a calendar year ensued before proceeding to revision sphincterotomy.

Thus, in patients who had clinically suspected treatment failure only 34 had followup videourodynamics in the study period, 32 after initial sphincterotomy and 2 after repeat sphincterotomy. Of these patients 8 had normal studies (low bladder pressures and good emptying) confirming success of the sphincterotomy and all of these were patients having an initial procedure only. Overall 25 patients in whom primary treatment failed and 15 in whom revision sphincterotomy failed did not have videourodynamics in the study period due to the reasons previously outlined. However, they continue to have clinical followup and none have required further surgical intervention.

In this study no sphincterotomy was revised due to renal function deterioration. The most recent serum creatinine for all patients in the study (median 60 μmol/l, range 38 to 146) indicates none had renal failure. No patient required transfusion postoperatively. As a secondary aim of the study global renal function was determined by cross-referencing our study database with dialysis and transplant databases. This indicated no patient required renal dialysis or transplantation due to renal function deterioration.

Discussion 

The treatment of SCI patients was revolutionized when clean intermittent catherization was introduced.7 It remains the gold standard for the treatment of SCI patients with DSD and has the goal of providing a balanced, low pressure bladder totally emptied at regular intervals without residual urine and leakage.3 External sphincterotomy has generally been considered the next best option for SCI patients in whom intermittent catheterization is not feasible2 and it has been demonstrated to reduce autonomic dysreflexia by more than 90%.8, 9 External sphincterotomy was also introduced with the ultimate aim of preserving renal tract function.

The main issues of concern regarding this established treatment are its potential irreversibility, the likelihood of needing repeat procedures and postoperative bleeding. However, in published series only approximately 10% of patients have reported postoperative bleeding and in most this did not require transfusion.10, 11 This is consistent with the absence of requirement for transfusion in our series.

The requirement for revision procedures in this series was considerable and we would regard external sphincterotomy potentially as a staged procedure, which may require intermittent repetition to provide for satisfactory bladder drainage rather than performance as a one-off intervention. When primary sphincterotomy fails it appears to do so reasonably early at a median of 36 months after surgery. This is approximately half the duration of efficacy where primary intervention alone was satisfactory (71 months). Where repeat sphincterotomy failed it also did so only after a prolonged intervention-free interval (mean 56 months). A 10-year retrospective analysis by Santiago also concluded that sphincterotomy ultimately had to be repeated in 9 of 25 patients.12

The adequacy of sphincterotomy may be difficult to gauge intraoperatively, especially if bleeding ensues, and consequent undertreatment may account for some instances of early revision requirement. A more complete sphincterotomy can be offered to achieve better drainage at a revision procedure. An alternative to electrosurgical incision is laser sphincterotomy. It offers several potential advantages because electrosurgery produces poorly defined effects that vary in depth unpredictably according to the electrical resistance of the target tissue. Alternatively the contact laser produces predictable and sharply defined areas of thermal effect with no bleeding.6 Several series have had encouraging results and perhaps a lower revision rate could be achieved with the laser. However, at this stage there are no long-term data to support this.6, 13

A strict definition of success of sphincterotomy was used in this study, with any event in which the long-term aim of the procedure was intermittently breached being regarded as a failure. However, not all patients who experienced such episodes (usually occasional UTI) required re-treatment. Although 57 of 84 patients (68%) were regarded as eventually experiencing treatment failure only 30 (35%) required reoperation. A single external sphincterotomy provided relief from further surgery in approximately two-thirds of spinal cord injured patients requiring treatment for detrusor-sphincter dyssynergia.

The results obtained in this series compare favorably to those for other treatment alternatives. Longer term complications with catheterization including sepsis, urethral injury and potential for malignant change in the bladder have resulted in this approach becoming obsolete as a definitive management strategy. There are limited data on treating DSD with prostatic balloon dilation. However, McFarlane et al reported a failure rate of 86% in a 1997 study of 14 patients.14 Of the failures 68% occurred within 12 months of treatment.

Urethral stenting also has been suggested as an alternative to sphincterotomy. Permanent versions (Urolume®) require a shorter hospital stay and less operative time.2 Stent migration, erosion and encrustation also ensue frequently, and have been reported in 15% to 30% of patients in those few studies with long-term outcome data.15, 16, 17 Stent migration invariably necessitates endoscopic removal.

Reversible urethral stents (Memokath™) offer a short-term solution which may be of potential benefit for recently injured patients who may recover sufficient dexterity to perform clean intermittent self-catheterization. They also may permit a return to antegrade ejaculation and fertility if temporarily removed. However, because they are designed as a temporary device, migration of these stents is even more frequent than with Urolume stents. There is evidence that the majority of stent removals are performed within 2 years of insertion.18, 19

Other more invasive methods available for managing DSD in SCI patients include ileovesicostomy or cystectomy.20, 21 No patients at our institution underwent either procedure particularly as ileovesicostomy has only recently become an alternative.21 More data will be required before ileovesicostomy becomes the standard procedure of choice in a SCI population. Furthermore, the general trend toward less invasive procedures makes such procedures difficult for many SCI patients to accept.

Conclusions 

A single external sphincterotomy provided definitive control of DSD in a SCI population in 27 of 84 patients (32%) and avoided the requirement of further surgery in 54 of 84 (65%). For optimal management of bladder emptying in this population sphincterotomy may require revision and should potentially be regarded as a staged procedure. Newer techniques of bladder management should have underlying risks benchmarked against contemporary low risk, durable outcome data for sphincterotomy. Importantly no patient in this large series experienced renal failure requiring dialysis or transplant after treatment with external sphincterotomy.