CHAPTER 7 Sensory disorders

INTRODUCTION

Urodynamic investigations were originally developed to study the ‘motor’ function of the lower urinary tract. However in recent years it has been recognized that the sensory component of voiding function is frequently involved in the pathophysiology of common lower urinary tract disorders such as the overactive bladder (OAB) syndrome. Bladder sensation can be assessed using stimulating electrodes introduced through the urethra, but such techniques are used for research purposes rather than routine assessment.

Urodynamic investigations are not ideal techniques for evaluating sensory disorders, which can be very subjective, but do allow some sensory information to be obtained and enable the observer to:

• measure the sensory thresholds objectively

• exclude motor disorders.

Abnormalities of bladder sensation can be broadly categorized into:

• increased bladder sensation (hyper-sensitive)

• reduced bladder sensation (hypo-sensitive).

HYPER-SENSITIVITY

Increased bladder sensation

This is defined, during filling cystometry, as an early first sensation of bladder filling (or an early desire to void) and/or an early strong desire to void, which occurs at low bladder volume and which persists.

Causes of hyper-sensitivity include:

• Idiopathic.

• Bladder or urethral inflammation:

bacterial cystitis

urethritis

urethral syndrome

post-irradiation cystitis

cyclophosphamide cystitis

chemical cystitis.

• Chronic prostatitis.

• Bladder pain syndrome/painful bladder syndrome/interstitial cystitis (BPS/PBS/IC).

• Bladder calculus.

• Bladder carcinoma.

Bacterial cystitis is the commonest cause; it is therefore important to ensure that there is no concurrent infection immediately before performing pressure/flow urodynamics, as the test will often exacerbate the urinary infection and will produce a falsely increased bladder sensitivity.

Evaluation of bladder hyper-sensitivity

Frequently patients with bladder hyper-sensitivity complain of storage symptoms and also supra-pubic pain in association with bladder filling.

A full history is particularly important in the assessment of hypersensitive disorders of the bladder. Clinical features can include:

• Daytime frequency – a prominent symptom for which bladder pain rather than impending incontinence is the trigger.

• Urgency – but rarely associated with incontinence.

• Bladder pain – usually relieved by voiding.

• Dysuria.

• Dyspareunia – a common symptom.

• Haematuria – requires full investigation of both the lower and upper urinary tracts.

The symptoms are usually chronic, often with a history of previous probable urinary tract infections; although frequently urine cultures have not been performed or the urine has been found to be sterile. Antibiotics have usually been unhelpful in providing long term relief from the symptoms. Women often report improvement at the end of their menstrual cycle and many will have had a hysterectomy, perhaps for lower abdominal/pelvic pain, but with no obvious gynaecological pathology.

Examination may be unremarkable, but attention should be paid to the urethral meatus, which may be inflamed or show mucosal prolapse (a urethral caruncle). There may also be bladder tenderness, both supra-pubically and on vaginal examination. A gentle bimanual examination will identify other pelvic pathology. The iliococcygeus muscle or pelvic side wall is often tender and trigger points may be identified.

All cases require urinalysis and culture to rule out an active UTI or haematuria. Often other investigations are indicated to exclude other causes for the symptoms including:

• urine cytology

• voiding diaries

• pressure/flow cystometry

• cystoscopy ± biopsy

• abdominal/pelvic ultrasound (to rule out gynaecological disorders).

Investigations of bladder oversensitivity are often complex with the requirement to exclude a number of pathologies. Figure 7.1 shows a possible management pathway for the investigation and management of this complex problem.

Figure 7.1 Algorithm for the management of hyper-sensitive bladder disorders. This is a complex area and such an algorithm usually has to be modified for each individual patient.

Management is also often difficult and options for bladder hypersensitivity and suspected BPS/PBS/IC include:

• Cystoscopy and overdistension (pressure of 80–100 cm H₂O for 5 min) and bladder biopsies of any abnormality as appropriate – this procedure is both investigative and in some cases therapeutic. There is usually a rise in pulse rate and blood pressure in patients with bladder hyper-sensitivity, under a light general anaesthetic; in addition, bleeding and non-specific glomerulations can often be seen in the bladder following the distension.

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Related posts:

Paediatric urodynamics Clinical evaluation of the lower urinary tract Urodynamic procedures Basic structure, function and control of the lower urinary tract Pressure/flow cystometry Storage disorders and incontinence

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