Does the Absence of Anal Reflexes Guarantee a “Safe Bladder” in Children with Spina Bifida?

Summary

Introduction: Increased detrusor pressure is a risk factor for renal damage in patients with neuropathic bladder, and probably requires inappropriate contraction of the external urethral sphincter. It seems logical that the absence of sacrally-mediated anal reflexes in a child with spina bifida makes such sphincteric spasm unlikely. One report has suggested that, in such circumstances, neuropathic bladder behaviour is usually predictable and safe. This article examines the reliability of this assumption, and whether routine urodynamic studies can be, therefore, safely omitted in this group.

Materials and Methods: 76 children and adolescents (aged 3 - 18 years) with spina bifida were tested for the presence of the anocutaneous reflex immediately prior to video-urodynamic studies, on entry into a therapeutic trial. The relationship between the anal reflex status and two surrogate indicators of urethral sphincter function, namely maximal detrusor pressure (MDP) and leak point pressure (LPP), was analysed.

Results: Only 11 (14 %) children had a positive reflex. Their mean MDP and their mean LPP were not statistically significantly greater than those in children without an intact reflex. Indeed the reflex was absent in the only two patients with MDP, ≥ 100 cm H₂O, and in the only five children with LPP, ≥ 60 cm H₂O.

Conclusion: The absence of anal reflexes is a poor predictor of safe bladder pressures in children with spina bifida. There is no justification for depriving such a population of routine urodynamic assessment on this basis. Our impression remains that there is probably no such entity as a predictably safe neuropathic bladder.

Key words

Spina bifida - Bladder dysfunction - Neuropathic bladder - Urodynamics

References

• 1 Abrams P, Blaivas J G, Stanton S L, Andersen J T. The standardisation of terminology of lower urinary tract function. Produced by the International Continence Society Committee on standardisation of terminology.  World J Urol. 1989;  6 233-245
• 2 Brown S, Marshall D, Patterson D, Cunningham A M. Chronic pyelonephritis in association with neuropathic bladder.  Eur J Pediatr Surg. 1999;  9 29-30
• 3 Cohen R A, Rushton H G, Belman A B, Kass E J, Majd M, Shaer C. Renal scarring and vesicoureteral reflux in children with myelodysplasia.  J Urol. 1990;  144 541-544
• 4 Marshall D F, Brown S, Patterson D. Do children with neuropathic bladder without vesico-ureteric reflux need regular DMSA scans? XLV Annual International Congress of the British Association of Paediatric Surgeons. 1998: A63
• 5 Pontari M A, Keating M, Kelly M, Dyro F, Bauer S B. Retained sacral function in children with high level myelodysplasia.  J Urol. 1995;  154 775-777
• 6 van Gool J D. Vesico-ureteral reflux in children with spina bifida and detrusor-sphincter dyssynergia.  Contr Nephrol. 1984;  39 221-237
• 7 Williams M P, Katz Z, Escala J M, Rickwood A M. Peripheral neurology as a predictor of bladder dysfunction in congenital neuropathic bladder.  Br J Urol. 1988;  62 51-53
• 8 Wyndaele J J, de Sy W A. Correlation between the findings of a clinical neurological examination and the urodynamic dysfunction in children with myelodysplasia.  J Urol. 1985;  133 638-639