The Denervated Pelvis

Professor Noel Clarke, Hope Hospital, Salford

Pelvic neuromuscular function involves complex and finely balanced system of autonomic homeostatic afferent and efferent regulation. This integrated and closely regulated control of this system is essential for balanced pelvic function. This includes storage and voiding functions of the bladder and differential sexual function in the male and female. The disruption of neuromuscular anatomy consequent upon pelvic pathology and its treatment by surgery ± radiotherapy results inevitably in the disturbance of function in a proportion of cases. The colorectal surgical and specialist nursing team must therefore have an understanding of this process in order to avoid the complications where possible and to counsel the patient appropriately where it is not. It is also important to remember that whilst many of the dysfunctional effects occur immediately, some will manifest in a delayed fashion.

Control of neuromuscular function involves central and peripheral autonomic pathways. These afferent and efferent nerve routes can be disrupted completely or partially by inflammation, surgical transaction or radiotherapy individually or in combination. The resultant clinical features may therefore be characteristic of complete denervation or they may present an incomplete of mixed picture.

Detrusor Effects
These comprise urinary retention, detrusor instability, stress incontinence or all of the above in combination. Accurate treatment is predicated on precise diagnosis: this requires full clinical and urodynamic evaluation by an experienced team. Simple tests will involve Frequency and Volume charts, pre and post micturition USScans, flow rate measurement and simple pad evaluation. More complex studies involve videourodynamics, ambulatory studies and pelvic floor EMG measurement.
Problems of pure obstruction may require bladder outflow surgery but this would potentially be the wrong treatment if the bladder was affected by primary detrusor instability. In this case the correct treatment would be use of anticholinergics, botulinum toxin or neuro-modulation as required. Detrusor failure would necessitate use of intermittent self catheterisation or an indwelling catheter whilst stress incontinence may need treatment with injectable bulking agents or artificial sphincter implantation in the male and colposuspension or urethral slings in the female.

Sexual Dysfunction
Pelvic dysfunction affects both the male and the female. The female tends to lose sensation/orgasm and secretory function. The male can suffer both erectile and ejaculatory dysfunction.
Ejaculatory dysfunction occurs in two ways. The first is because of disruption of the autonomic pathways driving prostatic/seminal vesicular function. The result is an irreversible loss of emission, with consequent infertility. Sperm retrieval from the epididymus is possible for some of these patients in the event that fertility is a concern. The second problem results from disturbance of adrenergic pathways supplying the smooth muscle of the bladder neck. This results in post surgical incompetence of the bladder neck with resultant retrograde ejaculation. This is also an irreversible effect but fertility is still possible with assisted conception techniques with post ejaculatory sperm retrieval from the urine.

Erectile dysfunction will occur in a proportion of men, even when they undergo nerve sparing TME. Patients with a degree of dysfunction beforehand are at even greater risk. Treatments include the use of PgE2 inhibitors (“Viagra” class drugs), injectable vasoactive agents, vacuum devices or penile implants. Treatments can be effective and useful but all have side effects and a significant failure rate.

Conclusion

Pelvic neuromuscular dysfunction is seen regularly following treatment of pelvic pathology. The surgical team need to be aware of this fact, avoiding the problems where possible by attention to technical detail. Patients should be counselled fully before treatment. In the event of post operative dysfunction expert opinion is required to achieve the best outcome