Hyperreflexia

Summary

The concept that elderly patients with urinary incontience due to detrusor hyperreflexia an be divided into two groups with differing natural histories on the basis of the detrusor contractility found on cystometry is reassessed.

Thirty patients shown to have hypedrreflexia on urodynamic study for persistent urinary incontinence following a recent neurological lesion had their contractility measured by the suggested criteria of the residual urine following a hypoerreflexic contraction and the rate of increase of detrusor pressure. The conistency of contractility on cystometry was also measued by repeating this three times on the same occassion.

A spectrum of values for the post-contraction volumes and the rate of increase of detrusor pressure was found. On repetitive cystomtry 11 out of 30 patients showed a variable post-contraction residual volume. While impaired contractility is common in detrusor hyperreflexia, the concept of two subgroups is not supported by these results. In some patients cystometric measures of contractility vary considerably on repeating the study on the same occasion.

Introduction

Detrusor overactivity often secondary to neurological lesions has been repeatedly shown by cystometric examination to be the commonest cause of urinary incotinence in the elderly patient [1]. Interest is now being directed into seeing whether different patterns of overactivity on cystometry have distinct clinical features and can lead to specific therapeutic measures that might guide management and improve the current resutls of treatment for this condition. Using the ice water and inhibition tests in addition to cystometry, Gerisson et al. [2] were able to distinguish three subtypes of overactive bladder in old age. Griffiths et al. [3] found different levels of urinary incontinence in patients with detrusor overactivity depending on whether bladder sensation was preserved or not. Resnick and Yalla [4] investigated patients with overt neurological lesions who had detrusor hyperreflexia and found two groups of patients on cystometric examination and on their results proposed a subclassification of this condition. They based this on the volume of the postcystometric residual urine with half their patients being found to empty the bladder almost completely with an uninhibited contraction, while the remainder evacuated very little. They proposed the term detrusor hyperrefleixa with impaired contractility, abbreviated to DHIC, for the group of patients showing less than 50% emptying. In addition, they found this subgroup also had a smaller rate of rise of detrusor pressure. They suggested there might be differences in the natural history of the two types, cases of DHIC being more likely to be precipiated into retention by anticholinergic therapy. If this proved correct the indications for cystometric examination in the elderly incontinent patient, now performed only on selected patients might be widened, as management could alter depending on the findings.

The aim of this study was to repeat the cystomectric study of post-conbtraction residual volumes and rate of rise of detrusor pressure in a group of patients under-going urodynamic investigation for persisting urinary incontinence due to detrusor hyperreflexia to assess how clearly the results suggested two subgroups. The consistency of detrusor contractility on cystometry was also assessed by repeating this three times on the same occasion.

Patients and Methods

Thirty patients, 26 women and four men, with a mean age of 80 (range 57-93) were studied. They were undergoing rehabilitation following a recent neurological lesion and had had urinary incontinence for less than 2 months. The incontinence had not responded to nursing measures. Before sutyd any urinary tract infections present were treated and faecal impaction relieved. The predominant clinical diagnoses were a recent stroke or a deterioration in Alzheimer's disease; the neurological lesions were all above mid-brain level. A preceding history of any symptoms suggestive of bladder outlet problems was an exclusion factor.

Patients were investigated by medium fill rate supine inflow cystometry, using a two-channel Elcomatic chart recorder. The study was repeated three times on the same occasion under similar conditions. All showed definite detrusor hyper-reflexia, i.e. they had a sudden uninhibitable rise of detrusor pressure at cystometry that exceeded 15 cm of water. Applying Geirsson's classification of blader overactivity [2] all cases would conform to his criteria for unhibited overactive bladder (UOB) and under Griffiths' criteria [3] they would be classified as showing motor urge incontinence due to an unstable detrusor contraction with reduced sensation of bladder fullness. Cystometric volume, post-contraction residual volume, and the maximum rate of increase in detrusor pressure were recorded on each occasion.

Results

As shown in the Figure a spread of results for bladder contractility as measured by the percentage of bladder emptying was found with no suggestio of a bimodal distribution. While in some patients the results on repeated cystomerty showed bladder evacuation to be similar on each of the hyperreflexic contractions, in others there was considerable variation. In 11 of the patients the percentage of bladder emptying ranged above and below 50% of cystometric bladder capacity on the different investigations. Such cases on the criteria suggested by Resnick and Yalla [4] would be difficult to classify as either cases of detrusor hyperreflexia or detrusor hyperreflexia with imparied contracility.

When the maximum rate of rise of detrusor pressure was examined in those patients who as shown in the Figure fulfilled Resnick and Yalla's criteria for either detrusor hyperreflexia or hyperreflexia with impaired contractility consistently, considerable overlap in values was found in the two groups. The mean maximum rate of increase in pressure in those with detrusor hyper-reflexia was 18.8 cm[H.sub.2]O/s (range 21-10 cm[H.sub.2]O/s and in those with DHIC the mean was 14.5 cm[H.sub.2]O/s (range 21-5 cm[H.sub.2]O/s).

Discussion

These results suggest that impaired contractility and the resultant residual urine occuring in elderly patients with detrusor hyperreflexia represent one end of a spectrum of contractility and do not represnetn a separate patient subgroup. In their paper Resnick and Yalla [4] suggested that further study might show this to be the case. However, their original report and this one involve small numbers of patients and for certainty a much larger group with detrusor hyperreflexia needs to be investigated.

This study has also demonstrated that in some patients there is considerable within-occasion variability in contractility on cystometry. This is also known to occur when this variable is mesured at different times, which suggests that a single measurement of contractility has limitations as a basic for classifying detrusor function.

The clinical importance of impaired detrusor contractility and its implications for patient management now need further study. It is certainly worthwhile measuring post-contraction residual volume routinely in elderly patients showing detrusor hyperreflexia where cystometry is perfomred without concomitant bladder screening facilities, to visualize the bladder contents after a contraction.

References

[1.] Castleden CM, Duffin HM, Asher MJ. Clincial and urodynamic studies in 100 elderly incontent patients. Br Med J 1981;282:1103-5.

[2.] Geirsson G, Fall M, Lindstorm S. Subtypes of overactive bladder in old age. And Ageing 1993;22:125-31.

[3.] Griffiths DJ, McCracken PN, Harrison GM, Gormley EA. Characteristics of urinary incontinence in elderly patients studied by 24-hour monitoring and urodynamic testing. Age Ageing 1992;21:195-201.

[4.] Resnick N, Yalla S. Detrusor hyperactivity with impaired contractile function: an unrecognised but common cause of incontinence in elderly patients. J AMA 1987;257:3076-81.

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