The normal bladder is characterized grossly by its pelvic position in the adult. In the older male, the macroscopic anatomy of the bladder is most commonly affected by the growth of the prostate gland. Although most commonly benign prostate growth occurs in the transition zone surrounding the urethra, occasionally this growth becomes unrestrained in a cephalad manner and pushes the trigone superiorly to give the bladder an elevated appearance radiographically. Gross inspection of the bladder interior often demonstrates a trabeculated appearance. Trabeculations are often thought to be a sign of chronic obstruction but have also been observed in the female bladder as well.1

In women, the anatomical position of the bladder is most often altered by defects in the pelvic floor musculature. This leads to the presentation of cystoceles, effectively a herniation of the bladder through the anterior vaginal muscle layers. This defect, as well as rectoceles and enteroceles are commonly noted in parous individuals although the impact of ageing, obesity and possibly neurological dysfunction can be substantial.2, 3 Perucchini has demonstrated localized striated urethral muscle loss with ageing at the bladder neck and dorsal wall of the urethra.4 Others have shown an increase in paraurethral connective tissue in elderly females with a reduction of blood vessels.5 Falconer has demonstrated that altered collagen production in women with stress incontinence and poor quality collagen seen in postmenopausal women possibly contribute to disorders related to prolapse in the elderly.6

The histologic appearance of the ageing bladder can give clues to its ultimate ability to function as a storage facility for urine. Ultrastructural changes in the ageing bladder include collagen deposition, muscle degeneration and axonal degeneration. The degree of these changes may correlate with specific abnormalities in voiding and incontinence such as detrusor overactivity and impaired contractility.7 Chronic ischaemia of the bladder may play a large causative role in these changes.8

Bladder function involves both the storage of urine and the expulsion of urine at a socially appropriate time. To maintain continence the storage of urine must occur under low pressures and the bladder must empty adequately. Unfortunately, ageing results in changes that occur intrinsically and extrinsically to the bladder that affect continence and emptying. Pathological changes are seen in the bladder due to ageing. In addition, nerve transmission can be altered due to age, disease states, surgical procedures, or drugs. Anatomic obstruction or lack of adequate support of the bladder neck also changes the ability of the bladder to empty and store urine.

The bladder consists of two parts: the body and the base or bladder neck. The smooth muscle fibres of the body are arranged randomly and those of the bladder neck are arranged in an inner longitudinal and outer circular layer. In the male urethra the sphincter consists of both smooth muscles and striated muscles. The external sphincter consists of the periurethral striated muscle and the intramural striated muscle or rhabdosphincter. In the female these muscle are attenuated. DeLancey proposes that female continence is created by a combination of muscular coaptation and passive compression of the urethra by the pubourethral hammock.11

During urine storage, low-level afferent bladder stimulation signals sympathetic contraction of the bladder neck and relaxation of the detrusor muscle or body of the bladder. This results in storage of urine under low pressure. The voiding reflex is initiated when afferent activity becomes intense. The pontine micturition centre stimulates the parasympathetic pathway and inhibits the sympathetic pathway resulting in relaxation of the bladder outlet and contraction of the detrusor muscle and thus bladder emptying. The striated external sphincter, which has separate innervation from the bladder neck, is also influenced by the pontine micturition and storage centres. The voiding reflex results in inhibition of the external sphincter and the storage reflex results in activation of the pudendal nerve.

The bladder must be able to distend and contract to adequately function. Structural changes in the tissues and abnormalities in bladder shape can alter urinary storage and emptying. Bladder compliance is a measurable value defined as the change in volume divided by the change in intravesical pressure. A normally functioning bladder fills under a low pressure therefore the bladder is compliant. Compliance is greatly affected by tissue composition, innervation and vascular supply.

Histological studies have shown that as collagen levels increase compliance is lost. Landau demonstrated that in bladders with poor compliance the ratio of type III to type I collagen was significantly higher than that of normal bladders.12 The aged bladder has a higher deposition of collagen; in addition, innervation of the detrusor smooth muscle changes with age. Neurochemical studies of human detrusor strips have shown an increase in purinergic neurotransmission and a decrease in cholinergic neurotransmission with age. It is felt that the shift in neurochemical transmission may change the resting tone of the bladder and contribute to the overactive bladder symptoms in aged bladders.13

Bladder wall blood flow is affected by the intramural tension. A bladder with poor compliance has increased intravesical pressure and intramural tension therefore, a greater decrease in bladder blood flow. Ischaemia can result in diminished contractility and can result in patchy denervation. The end result is a bladder that poorly empties and may have detrusor instability.14 Injured areas of the bladder can become weak and form diverticulum resulting in ineffective bladder emptying.

The complexity of voiding dysfunction in the aged bladder makes if difficult to determine changes in the bladder secondary to the normal ageing process versus changes as the result of bladder outlet obstruction or diseases effecting the nervous system and/or vascular supply. Certainly the lower urinary tract symptoms of obstruction, instability and impaired detrusor function often overlap. The changes seen in bladder function with ageing must certainly overlap as well. A study by Homma found the symptoms of urgency, frequency and nocturia increased with age in both men and women. The cystometric capacity declined with age in both sexes.15

Histological changes in the aged bladder have been documented including increased collagen deposition, widened spaces between muscle fibres and ultrastructural changes of the smooth muscle cell membrane.7 Elbadawi also showed that aged bladders without urodynamic evidence of obstruction had muscle cell membranes with dominant dense bands and depleted caveolae.7 These finding were reproducible and different from the ultrastructural changes seen with obstruction, overactive or hypocontractile bladders. These findings are felt to represent dedifferentiation of the smooth muscle fibres.

Changes in bladder compliance, nerve transmission and vascularity occur as the bladder ages. Certainly multiple disease processes may worsen these changes. With advanced age expected bladder symptoms might include increasing frequency and urgency with a decreased bladder capacity.

Several disease states especially affect the bladder in the geriatric population. Whether caused by neurological disease, endocrine problems, iatrogenic intervention or the ageing process itself, these problems exact particular morbidity on the lower genitourinary tract. The following conditions are particularly important.

Parkinson’s Disease

Parkinson’s disease affects 1% of all patients over the age of 60 and is rarely seen in those under 40. In addition to the characteristic tremors and motion deficits, the loss of dopaminergic neurons in the substantia nigra of the basal ganglia affects voiding by reducing the inhibitory effect of the basal ganglia on the micturition reflex as demonstrated in several animal studies.16

The voiding symptoms of Parkinson’s disease are frequency, urgency and urge incontinence. These irritative symptoms are present in well over half of all patients with the disorder.17 A significant problem from a diagnostic viewpoint is the presence of these symptoms in elderly males. These irritative voiding symptoms mimic the lower urinary tract symptoms (LUTS) associated with bladder outlet obstruction related to benign prostatic hyperplasia (BPH). Without urodynamic evaluation, the neurogenic component to the symptoms may be overlooked or not quantified well and inappropriate therapy instituted. Furthermore, men with multiple systems atrophy rather than in true Parkinson’s disease may actually have mild detrusor-sphincter dyssynergia, which again could mimic the obstructive symptoms of BPH.18

The typical urodynamic findings of Parkinson’s are detrusor hyperreflexia on filling cystometry. As much as 79% of bladder dysfunction in these patients can be related to hyperreflexia.19 Other findings are not uncommon though. Hyporeflexia is present in 16% of patients in Araki’s study.19 Obstruction can also be present particularly in the male with prostatic enlargement or stricture disease from previous interventions. Multichannel urodynamics is essential to the evaluation of voiding dysfunction in patients with Parkinson’s disease.

Cerebrovascular Accident (CVA)

Stroke can be considered a major health problem among elderly patients. Approximately three-quarters of the roughly 400 000 stroke patients per year in the United States are over 65 years old. The impact of this disorder on voiding and continence can range from mild to profound. When occurring in the aged patient, its effects can magnify pre-existing bladder conditions and cause great confusion as to proper therapy. Depending on the location of the ischaemic event, the bladder may range from hyperreflexic to areflexic. One can therefore present with an entire range of symptoms anywhere from nocturia and urgency/urge incontinence to voiding difficulties and urinary retention.20 The presence of urinary incontinence in the acute phase of a CVA is a powerful predictor of a negative outcome.21

The patient presenting with lower urinary tract symptoms following a CVA can be a diagnostic dilemma. In one study, detrusor hyperreflexia was seen in 68% of patients, detrusor-sphincter dyssynergia in 14%, and uninhibited sphincter relaxation in 36%.20 In that same study, there were patients with retention who were noted to have detrusor areflexia with an unrelaxing sphincter. No correlation was seen between site of lesion and urodynamic findings. In the elderly post-CVA male, neurogenic bladder problems may coexist with obstruction from the prostate gland. Nitti found in a group of men with a mean age of 70 with voiding complaints following a stroke that detrusor hyperreflexia was present in 82% of the group, but pressure-flow characteristics of definite obstruction were present in 63%.22 Multichannel urodynamics can be an important adjunct in the urological management of these patients.

Nocturia

Nocturia is commonly listed as a symptom by the older patients. In males it is often perceived as related to prostate enlargement. But this symptom is commonly noted in ageing women.23 Menopausal status may contribute to the presence of nocturia.24 In all likelihood, nocturia is a manifestation of normal ageing.

Other factors impacting the presence of nocturia in the ageing individual include sleep difficulties and nocturnal polyuria. Sleep disturbances are common in the elderly population and nocturia may be more related to those problems as opposed to a urinary tract dysfunction. Furthermore, the patient with nocturia from whatever cause will have poorer sleep.25 The problem of nocturnal polyuria in many of the elderly, which is reported as nocturia can be difficult to manage. With lower renal concentrating ability, poorer conservation of sodium, loss of the circadian rhythm of antidiuretic hormone secretion, decreased production of renin-angiotensin-aldosterone, and increased release of atrial natriuretic hormone, there is an age-related alteration in the circadian rhythm of water excretion leading to increased night-time urine production in the older population. Exacerbated by age-related diminution in functional bladder volume and detrusor instability, nocturnal polyuria often leads to a dramatic version of nocturia.26 Whatever the cause, nocturia is a significant problem both from a QOL standpoint and as a risk factor for falls leading to hip fractures.27 Essentially, nocturia more than twice per night is significantly associated with the risk of falls and subsequent fractures.

Dementias

The elderly patient with dementia faces the dual difficulties of having to face an ageing bladder with its consequences and in addition, the difficulties caused by an altered perception of his or her internal and external environments. This can lead to urinary incontinence and/or retention based on either bladder factors or due to central neurological misperceptions of urinary activity. The difficulties in management of these patients’ other significant conditions often pushes concerns over incontinence aside but the fact is that incontinence issues are the primary cause for institutionalization of the elderly patient.

Evidence of combined cerebral and urinary tract dysfunction comes from perfusion studies in elderly patients. From PET scan studies it has been demonstrated that the pontine micturition centre in the dorsomedial pontine tegmentum, the periaqueductal grey matter and the pre-optic area of the hypothalamus are all active during various phases of micturition.28 Furthermore, urge incontinence has been associated with underperfusion of the frontal areas of the brain.29