INTRODUCTION

Neurogenic bladder dysfunction describes abnormal function of the bladder and urethra due to lesions affecting their innervation, either within the central nervous system or in the peripheral nerves of the lower urinary tract.

Neurological conditions can alter bladder and urethral function by altering:

PATTERNS OF NEUROGENIC DYSFUNCTION

Although each individual patient will have a unique pattern of lower urinary tract dysfunction and require an individual management plan, the site of the lesion gives an indication of the likely pattern of the dysfunction.

Neurological lesions can be divided into four broad anatomical areas:

URODYNAMICS FOR NEUROGENIC BLADDER DISORDERS

In the management of neurogenic lower urinary tract function:

• The primary aim is to protect the upper urinary tract:

to maintain low intra-vesical pressures

to maintain a low post-void residual.

Urodynamic investigations can characterize the nature of the detrusor and sphincteric abnormality to:

Many patients with neurological disorders don’t display symptoms or signs until significant damage has occurred to the upper tracts or to detrusor function. Frequently urodynamic findings in this group of patients do not correlate well with the neurological examination findings and therefore the examination findings should not be used to plan the urological management. Instead all patients with neurological dysfunction that affects or is likely to affect lower urinary tract function should receive a thorough urodynamic assessment at an early stage to fully characterize the function and to plan appropriate management; patients may require subsequent follow-up urodynamic investigations to determine the success of any intervention and the extent of any change in lower urinary tract function.

Assessment of lower urinary tract dysfunction is no different from that in neurologically normal patients, consisting of history, examination, voiding diaries, uroflowmetry and pressure flow studies (± EMG). However the interpretation is often more complex and there are specific hazards such as autonomic dysreflexia; therefore the investigations are best performed in specialist centres using video urodynamics. It must be remembered that patients with neurogenic bladder dysfunction also suffer from the same lower urinary tract disorders as the rest of the population, e.g. BOO related to the prostate, and these conditions may further complicate assessment and management. Management should be tailored for each patient depending on the pattern of dysfunction and a plan for follow-up, other relevant investigations (renal function, ultrasound) and repeat urodynamic assessments should be carried out.

NDO AND SPHINCTER OVERACTIVITY (DSD)

The presence of both NDO and sphincter overactivity is a particularly dangerous urodynamic situation and as a rule of thumb those patients with a competent bladder outflow and a pre-micturition pressure of 40 cm H₂O or higher are at particular risk of developing upper urinary tract problems due to the high backpressure, although this is by no means an absolute value and damage to the upper tracts can occur at lower pressures (Figure 9.1). If this pattern of dysfunction is present then the preservation of renal function is of the utmost importance; this requires control of both the NDO and the sphincter overactivity.

Figure 9.1 Video urodynamic screening in a spinal cord injured patient, showing obstruction at the level of the sphincter (DSD), right vesico-ureteric reflux and hydronephrosis and also multiple bladder diverticuli.

Treatment strategies for the NDO include:

Treatment strategies for the overactive sphincter are to ensure adequate drainage; these include: