Investigation of the Neurogenic Bladder

6 6Journal ofNeurology, Neurosurgery, anid Psychiatry 1996;60:6-13 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.60.1.6 on 1 January 1996. Downloaded from NEUROLOGICAL INVESTIGATIONS

Investigation of the neurogenic bladder

Clare J Fowler

Methods of examination which have been analogue signals but with the advances in used to investigate the neurogenic bladder electronics and development of microchip include tests of bladder function, so-called technology the machines have become pro- "urodynamics", and neurophysiological tests gressively more complex, more "intelligent", of sphincter and pelvic floor innervation. A and mostly easier to use. Today measured possible consequence of a neurogenic bladder is pressures are digitised allowing on line, real damage to the upper urinary tract but the time computer analysis of signals. investigation of such complications is essen- During the development of urodynamics an tially urological and is only briefly mentioned important advance came with the introduction in this review. of facilities to record pressure measurements superimposed on the fluoroscopic appearances of the bladder, a "videocystometrogram". History of the development of This combination provides a complete picture investigations of the behaviour of the bladder both during URODYNAMICS filling and emptying although it is expensive The term "urodynamics" encompasses any and exposes the patient to x rays. Much can be investigation of urinary tract function although learnt from simple cystometry alone and it is it is often used colloquially as a synonym for this investigation which is now a standard cystometry. Cystometry, the measurement of facility in almost every district general hospital bladder pressure, has been the main tool used with a urology department. to show abnormal behaviour of the neurogenic The hydrodynamic problems of measuring bladder. fluid flow are different from measuring pres- The earliest reference to a study measuring sure within an organ. Introduction of simple bladder pressure is commonly given as the and cheap equipment for measuring urinary http://jnnp.bmj.com/ paper by Mosso and Pellacani published in flow rate' has led to this becoming routine; 1882.1 With a water manometer they showed combined with ultrasound measurement of that bladder pressure rose at the start of mic- the postmicturition residual volume, it pro- turition and then gradually declined but that vides a simple non-invasive means by which during storage the pressure measured within much valuable information can be obtained the organ gave little indication of what volume about lower urinary tract function. it contained. However, the paper which

described a technique for cystometry produc- NEUROPHYSIOLOGICAL INVESTIGATIONS on September 26, 2021 by guest. Protected copyright. ing what is regarded as the precursor of modem Various types of neurophysiological investiga- day urodynamic recordings was published in tion of the pelvic floor and the sphincters have Brain in 1933 by Denny-Brown and been developed over the years. A neurophysio- Robertson2 from the National Hospital for logical method for recording the bulbocaver- Nervous Diseases, Queen Square. By means nosus reflex, regarded as clinically valuable in of an ingenious system of mirror manometers assessing patients with neurogenic bladder dis- they recorded intravesical and intraurethral orders, was first reported in 1967." pressure with two transurethral catheters (one Neurophysiological recordings of various inside the other), as well as recording rectal, pelvic floor reflexes were much in vogue in the perineal, and abdominal wall pressures in 1970s but have since lapsed and have been three neurologically normal men. From their transiently replaced by an enthusiasm for findings they defined the physiological recording the pudendal evoked potential. sequence of processes which occur with blad- Recording from the striated muscle of the der filling, the initiation of micturition, and urethral sphincter or anal sphincter during voiding to completion. cystometry was first recommended as a means The introduction of cystometry into clinical of detecting inappropriate sphincter contrac- disorder The National Hospital practice was gradual and by the 1960s it was tion during detrusor contraction, the for Neurology and being used in only a few specialised urological known as detrusor sphincter dyssynergia.7 For Neurosurgery, centres.3 When commercial equipment first several reasons this type of kinesiological Queen Square, London now little used sphincter WC1N 3BG, UK became available it consisted of a series of pen EMG is although C J Fowler recorders which recorded pressure changes as EMG performed as a separate neurophysio- Investigation of the neurogenic bladder 7

Figure 1 Filling J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.60.1.6 on 1 January 1996. Downloaded from cystometry in a healthy subject. Vinfus = infusion at 50 mllminute;

Pabd = intrabdominal ...... : ......

. . . . . pressure measured by the ...... I I I . . . :

. = ...... : . . . .. rectal line; Pves . . I . . intravesical ...... pressure; . = ...... I . Pdet Pves-Pabd...... :

Respiratory movements, I III I I I . . . . . II . I I I which were not recorded ...... I . I : ...... h. with the intravesical --A-P%&amLm&A- Pves J _...... pressure measurements, 10 cm H20 were recorded with the rectal pressure line so that these appear as an artefact ~~~~~~~~~~~~~~~~~~~~~.... Pdet due to subtraction on Pdet. 10 cm H20 In the early part ofthe trace the subject was asked to @...... @.. ;@@...... cough and the subtraction Pabd

...... ofPabdfrom Pves was 1...... -.. 10 cm H20 complete so that no rise in Pdet is recorded. Vinfus ...... @*...... - 1:13 3:13 5:13 7:13 9:13 100 ml

Cough Time (min:s)

logical test remains a valuable investigation in ical and intrabdominal pressures a fine some circumstances. catheter is passed through the urethra into the bladder and another into the rectum. The catheter used to monitor intravesical pressure Principle underlying investigations is passed, together with a somewhat wider CYSTOMETRY diameter catheter through which the bladder is Cystometry is the recording of the pressure- filled. Important information is obtained if volume relation of the bladder. The intravesi- detrusor pressure is measured both during fill- cal pressure is measured and by subtracting ing and while the patient attempts to mic- the intra-abdominal pressure from this figure turate. In the interests of saving time an an estimate of the true pressure produced by unphysiologically rapid rate of filling of 50 the smooth muscle of the detrusor is obtained. ml/min is commonly used in cystometric This is best seen by looking at the preparatory studies. stages of cystometric recordings when the Recently, methods have become available patient is asked to cough (fig 1). Coughing for recording bladder pressures over periods of raises the intra-abdominal pressure and thus many hours and the bladder is left to fill natu- the measured intravesical pressure but under rally, so-called "ambulatory urodynamics".8 physiological conditions the detrusor does not In patients with neurogenic incontinence http://jnnp.bmj.com/ then contract so that the derived detrusor the commonest finding is of an abrupt rise in pressure (Pdet) remains unchanged or detrusor pressure which the patient is unable becomes slightly negative because the intra- to suppress and which is usually accompanied abdominal pressure may rise more than the by reports of urinary urgency (fig 2). If the intravesical pressure. To measure the intraves- patient is recognised as having a neurological

Figure 2 Detrusor hyperreflexia in a woman on September 26, 2021 by guest. Protected copyright. with multiple sclerosis. to 100 ml ...... Afterfilling . . . . : ...... (vinfus) there was a Q r detrusor contraction which ...... 5 m Is ...... * ...... resulted in a pressure rise of A ... 90 cm H20. Vinfus ...... ,i. 100 ml

Pves

~~~~~~~~~~~~~~~...... 10 cm H20 ...... --*-.....t*t* ---- -*v* @@*-

Pdet :1*\...''.''''..'...... 10 cm H20

@o@@@@v**-**-*vv*s~~~~~~~~~~~...... Padb 10 cm H20

1:02 2:02 3:02 4:02 5:02 ~~~~~~~~~~~~~~...... Time (min:s) 8 Fowler J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.60.1.6 on 1 January 1996. Downloaded from Figure 3 Abrams 100 - This has resulted in a large body of medical nomogram. Using values literature in which patients are classified for the maximalflow a 80 - (Qmax) and the I Obstructed according to their urodynamic findings rather corresponding voiding E 60 - than by the underlying pathophysiological a -0 detrusor pressure (Pdet) 40 - cause and diagnosis. point can be plotted on the Equivocal In patients with suspected obstruction of nomogram that determines CL 20 - Unobstructed whether the bladder outlet is / 1 outflow, particularly men with prostatic hyper- obstructed, unobstructed, or 0- trophy, measurement of detrusor pressure equivocally obstructed. ) 5 10 15 20 Qmax (ml/s) during voiding is important. This, together with urinary flow rate provides information about the outflow tract" and an estimate of condition, this is called "detrusor hyper- the presence of obstruction can be made reflexia", the condition is otherwise referred to (fig 3). as "detrusor instability"9-the cystometric changes in the two conditions being indistin- UROFLOWMETRY guisable. The cause of detrusor instability is Uroflowmetry is the measurement of urinary unknown but the weight of opinion is shifting flow rate. This is a non-invasive investigation. from thinking that it has a psychogenic cause The patient presents with a full bladder and or is due to an occult neurological lesion to the voids into a receptacle in the base of which is a view that it may be due to a disorder of the spinning wheel. Urinary flow slows the rate of detrusor muscle itself.'0 Likewise the causes of rotation and from this a graphical output of failure of bladder emptying cannot be identi- flow rate can be obtained (fig 4). fied from cystometry, and urological and neu- Abnormalities of flow can be due to local rological disorders can cause indistinguishable urological problems such as prostatic hyper- cystometric abnormality. Because bladder trophy, a urethral stricture, or neurogenic dis- behaviour cannot always be predicted from the orders of the bladder outlet mechanism. patient's history it has been argued that urody- Detrusor sphincter dyssynergia, which occurs namic investigations are important in the with spinal cord disease, is a common example investigation of urinary complaints but the of this and results in interrupted flow (fig 5). failure of urodynamics to provide anything Uroflowmetry combined with ultrasound more than a description of bladder dysfunc- scanning of the postmicturition residual vol- tion has not been properly acknowledged. ume is used as a screening test to exclude seri-

Figure 4 Uroflowmetry. The lower trace shows the rate of urinaryflow, which ...... reaches a maximum of 40 ...... : ...... : ...... mlls in three seconds and ...... I II II II I I : ...... then declines. The upper ...... : ...... trace is the result of ...... I I I I I I I I I : ......

. I ...... http://jnnp.bmj.com/ ...... integrating the flow rate ...... : :I . ..' ,....

...... III I I I I I I :. . . . . and shows that a total of . ... . : Vu ro . . . . I I ...... *.. . 275 ml was passed...... : :I . 100 ml . . ---dar - ...... -...... II...... ;------

......

...... Qura ...... 5 ml/s w. . . - 4 14 24 34 44 Time (s) ..--

Figure 5 Uroflowmetry in a patient with multiple sclerosis. He was paraparetic and had 50 ml/s flow rate :: :: frequency and urgency but also symptoms ofdifficulty voiding and was shown to have incomplete bladder ...... emptying. This interrupted ...... flow pattern is the result of ...... contractions of the striated urethral sphincter occumng during the detrusor contraction that is, "detrusor sphincter dyssynergia ". ..~~~~~.10 ~~~~~~~~~~~~~.20 30 40 50 60 70 80 90 Investigation of the neurogenic bladder 9 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.60.1.6 on 1 January 1996. Downloaded from ous outflow obstruction and can also provide the region are not tested. Possibly tests of the information for planning bladder management autonomic innervation of the genital region in patients with neurological disease. will prove more useful.2' Recording the pudendal evoked potential is ULTRASOUND SCANNING OF THE URINARY similar to recording tibial evoked potentials. TRACT The same cortical recording electrodes can be The residual volume left after voiding is used and it is advisable to record the tibial important, and can readily be measured with a evoked responses first to familiarise the patient small inexpensive ultrasound scanner. Great with the technique. The patient is then asked precision is not needed it is simply enough to to hold the stimulating electrode on the dorsal know whether there is more or less than 100 nerve of the penis or clitoris and a similar ml an obvious abnormality on ultrasound number of stimuli as needed for obtaining the scanning which does not need great expertise tibial evoked potentials are given. Surprisingly to recognise. Most scanners have cursors that the latency of tibial and pudendal responses is can be placed on the black outline of the urine similar despite the difference in conduction in the bladder and from this, assuming a distance. This is thought to be due to the spherical shape to the bladder, bladder volume slower conduction velocity of the pudendal can be calculated. afferents compared with fast conducting muscle Ultrasound scanning has largely overtaken afferents which respond when the tibial nerve intravenous urography as the method of at the ankle is stimulated.22 choice to examine the upper renal tract to The introduction of a method to record the detect dilatation but intravenous urography pudendal evoked potential was initially hailed remains the preferred method to look for as promising.23 It was considered that this ureteric stones. With modern, highly complex would provide a means of testing the afferent three dimensional scanning, details of the innervation from the sacral region and cer- structure of the lower urinary tract can tainly the responses were delayed in patients be made out.'2 This has exciting possibilities with conditions such as multiple sclerosis.2426 for both urologists and urogynaecologists. Like the lower limb somatosensory evoked potentials, the pudendal evoked potential is NEUROPHYSIOLOGICAL INVESTIGATIONS OF THE delayed if there is spinal cord disease but this SPHINCTERS AND PELVIC FLOOR is also usually apparent on clinical examina- Clinical neurophysiological techniques for tion. Recent studies have shown that the examining the pelvic floor have been used for pudendal evoked potential is very rarely many years. These studies have greatly abnormal unless there are other clinical signs enhanced our understanding of the physiologi- of neurological disease27-29 and furthermore if cal and pathophysiological mechanisms of the lesion is predominantly unilateral the neural control of the lower urinary tract. pudendal evoked potential can be within nor- The first neurophysiological measurements mal limits.29 It seems that there is little diag- made were of sacral reflexes starting with the nostic gain in recording the pudendal evoked bulbocavemosus reflex.6 '1 To record this potential although it is sometimes reassuring reflex either a surface or a needle electrode was to show that it is normal in patients in whom placed over or in the bulbocavemosus muscle neurological problems are suspected. http://jnnp.bmj.com/ and electrical stimuli were applied to the dorsal A technique for measurement of the termi- nerve of the penis. The time taken for the nal motor latency of the pudendal and perineal reflex contraction of the muscle to occur after nerves (PTML) was devised at St Mark's the stimulus was measured. After the intro- Hospital.30 It has been used to show patho- duction of this technique various other pelvic physiological changes in these nerves in floor reflex contractions were recorded14 and it women with faecal,30 urinary,3 or double

was shown that equally useful responses could incontinence.32 The pudendal nerve is stimu- on September 26, 2021 by guest. Protected copyright. be obtained by recording from the urethral or lated transrectally near the ischial spine anal sphincter or other parts of the striated through the wall of the rectum using an elec- muscle of the pelvic floor.') 1'It was argued trode mounted on the tip of the examiner's that abnormalities of the sacral roots, both finger. An electrode is mounted at the base of efferent and afferent, would lead to a delay in the finger, which records from the anal sphinc- this reflex and this did indeed prove to be the ter, and a ring electrode mounted on a Foley case in patients with established cauda equina catheter can be used to record from the peri- lesions.'3 18 19 However, it was found that reflex urethral striated muscle. The latency of the responses could still be elicited in patients with response has been found to be prolonged in partial cauda equina lesions20 and more impor- women with urinary stress incontinence after tantly these tests were of little value when childbirth and women with faecal inconti- applied to patients with uncertain neurological nence due to sphincter weakness. It is thought lesions presenting with hypocontractile blad- that stretching of the nerves during parturition ders or impotence. The explanation for this is and also with straining at defaecation in probably that, as with other reflexes measured chronic constipation results in pudendal nerve using clinical neurophysiological techniques, injury.33 Although of considerable research only the responses mediated by large myeli- value this test is not used in the routine assess- nated fibres are recorded. The small myeli- ment of women with urinary stress inconti- nated or unmyelinated fibres which either nence, nor has it proved to be as useful as innervate the smooth muscle or constitute the electromyography of the anal sphincter in the functionally important afferent nerve supply of assessment of faecal incontinence.34 10 Fozuler J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.60.1.6 on 1 January 1996. Downloaded from Electromyography (EMG) of the striated has been called "complex repetitive discharges musculature of the pelvic floor is of value in and decelerating bursts".'" Detailed EMG recognising changes of denervation and analysis of this activity, measuring the jitter of chronic reinnervation in patients with cauda the component potentials, has shown that in equina lesions as well those with suspected common with other complex repetitive dis- multiple system atrophy. A single fibre needle charges, it is due to ephaptic transmission may be used to show changes in fibre density3' between muscle fibres"' and it has been sug- or a concentric needle electrode to show gested that it is this activity which can be changes in configuration of individual motor recorded as a continuous phenomenon which units which result from reinnervation.36 prevents the muscle from relaxing. The stri- The striated muscles of the sphincters are ated muscle of the urethral sphincter is a cir- innervated by anterior horn cells that lie in cularly placed horseshoe-like structure and it Onuf's nucleus in the sacral part of the spinal is not difficult to see how a failure of it to relax cord. Neurophysiological studies showed loss would result in either obstructed voiding or of cells in Onuf's nucleus in patients dying urinary retention. Why the abnormal activity with Shy-Drager syndrome.7 These pathologi- should develop remains unknown but it is not cal changes may be reflected in abnormalities uncommon for women with urinary retention of sphincter EMG in life. This was first shown to have clinical features of polycystic ovaries. 15 by Sakouta et aP8 and then in a systematic A speculative hypothesis is that the striated study by Kirby et al.39 Sphincter EMG is now muscle of the urethral sphincter, being hor- used to distinguish between patients with monally sensitive, undergoes a breakdown in bladder symptoms and multiple system atro- membrane stabilisation secondary to the per- phy and atypical parkinsonism and those with vading hormonal abnormality of polycystic idiopathic Parkinson's disease,404' and a uro- ovary syndrome allowing ephaptic transmis- logical disorder as in the first condition sion between muscle fibres to occur. changes of reinnervation can be found which Unfortunately no specific treatment has yet are not present in the second. Changes of rein- been effective and the women manage best by nervation in multiple system atrophy are non- performing intermittent self catheterisation. specific and some caution must be exercised in A similar abnormality has not been found in interpreting EMG findings in multiparous men and extensive neurophysiological testing women or patients who have had extensive has failed to show a defect in the less com- pelvic surgery. However, the changes which monly encountered young men with urinary occur in the motor units in multiple system retention without a urological explanation. atrophy are so extreme as to make the test reli- The role of primary detrusor abnormality in able and robust. these men needs to be explored as it does in Using a concentric needle electrode 10 dif- patients with idiopathic detrusor instability. ferent motor units are recorded from either the Unfortunately there is as yet no neurophysio- urethral or anal sphincter, the anal sphincter logical means of investigating detrusor smooth being more accessible and therefore less muscle function. uncomfortable for the patient but equally valuable for giving a significant result. The mean duration of the 10 motor units is measured as Planning investigations http://jnnp.bmj.com/ well as the number of units which exceed 10 Investigations of bladder symptoms are carried ms in duration. In multiple system atrophy, out for two very different purposes: with blad- some motor units remain of normal duration, der symptoms and established neurological but others become excessively prolonged. By disease urodynamic investigations may be per- contrast with this-for example, after multiple formed to try and understand the pathophysio- deliveries all the units might be mildly pro- logical basis for the patient's symptoms and

longed. The values used to define normal are a obtain information on which to base recom- on September 26, 2021 by guest. Protected copyright. mean duration of less than 8-5 ms and less mendations for management of incontinence. than 20% of units having a duration of less When the question is being asked "is this a than 10 ms.40 A mean duration of more than neurogenic bladder?" a different approach is 10 ms is highly abnormal and suggestive of required. In this instance investigations are of multiple system atrophy but there is inevitably a neurological or neurophysiological nature. an area of uncertainty when the mean value is less than this. URODYNAMIC INVESTIGATIONS IN PATIENTS The other condition in which urethral WITH ESTABLISHED NEUROLOGICAL DISEASE sphincter EMG has proved to be of particular Poor bladder control is a common and trou- value is in the investigation of young women blesome feature of many types of neurological with urinary retention.42 These patients have disease, especially of the spinal cord. The no neurological signs on clinical examination commonest complaints are of urgency, fre- and in particular no evidence of spinal cord quency, and urge incontinence and in estab- disease.43 It was previously suggested that they lished neurological disease these can be were either presenting with urinary retention assumed to reflect detrusor hyperreflexia. as the first symptom of multiple sclerosis or However, patients with neurogenic bladder that they had a hysterical disorder. The first is disorders often have a disorder of emptying as now easy to disprove as imaging and neuro- well; incomplete emptying is probably due to a physiological investigation in these women combination of detrusor sphincter dyssynergia show no appropriate abnormality. Sphincter and poorly sustained detrusor contractions. If EMG shows a myotonic-like activity which the bladder does not empty completely the Investigation of the neurogenic bladder I11

persistent postmicturition residual volume acts with anticholinergic drugs is that although J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.60.1.6 on 1 January 1996. Downloaded from as a stimulus for repeated detrusor contrac- they may be effective in lessening detrusor tions so that efforts to treat detrusor hyper- hyperreflexia they can adversely affect bladder reflexia are unlikely to succeed until effective emptying. It is advisable therefore if a patient emptying is achieved. The most effective treat- starts on these drugs and fails to respond to ment for detrusor hyperreflexia is an anti- recheck the postmicturition residual volume cholinergic drug (oxybutynin is currently and make sure that this has not significantly recommended) but there is no oral medication accumulated. which improves neurogenic voiding disorders If the patient has recurrent urinary tract and the best management is intermittent infections or fails to respond to the regimen catheterisation, performed by the patient or outlined in fig 6, it is advisable to refer the carer. patient to a urologist who will carry out investi- In summary the presence of detrusor hyper- gations to exclude urinary tract stones or some reflexia may be reliably deduced from clinical other structural lesion. history, but incomplete emptying, although Although cystometry is not critical in the contributing appreciably to the problem, can routine investigation and management of be largely asymptomatic. For this reason the patients with neurological disability such as single most important investigation when multiple sclerosis, there are other neurological planning the management of patients with conditions in which measurements of bladder neurogenic incontinence is measurement of pressure are important. This is particularly the the postmicturition residual volume. This can case in patients with parkinsonian features and either be done by simple ultrasound (see ear- bladder symptoms. There must be a high lier) or by "in-out" catheterisation. The index of suspicion of multiple system atrophy advantage of using catheterisation is that it in such a patient, best investigated by sphinc- familiarises the patient with what is involved in ter EMG (see earlier). If, however, sphincter intermittent self catheterisation. EMG is normal and the disorder seems to be Investigation of the postmicturition residual idiopathic Parkinson's disease the question of volume is recommended before starting on an prostatic obstruction of outflow in men arises anticholinergic drug, as shown in the algo- and full cystometry with a voiding study is rithm in fig 6. A further point about treatment essential. Cystometry is also of value when investigating patients with an uncertain neurological Figure 6 Algorithm for diagnosis who have among their symptoms management ofpatients complaints of bladder dysfunction. Finding with neurogenic bladder disorders. By following this sensory urgency may provide an explanation both aspects of bladder for bladder symptoms without suggesting a dysfunction-incomplete neurogenic basis. emptying and hyperreflexia-are treated. IS THIS A NEUROGENIC BLADDER? The role of urodynamics in trying to decide if a patient has a neurogenic bladder disorder is limited. In most patients sent by urologists to http://jnnp.bmj.com/ neurologists, filling cystometry has disclosed bladder overactivity. In this instance the neurologist must try to confirm or refute that there is a neurological basis for the problem. Foremost in the patient's assessment is the clinical neurological examination. on September 26, 2021 by guest. Protected copyright. The clinical neurological examination The neural organisation of control of bladder function is widely distributed throughout the neuraxis. The neural programmes which determine whether the bladder is in storage or voiding mode exist in centres in the dorsal tegmentum of the pons.46 For these programmes to be effected there must be intact connections between the sacral part of the spinal cord, which is the level of efferent and afferent neural connections to the lower urinary tract, and the pons. Spinal cord abnormality is therefore a common cause of neurogenic bladder dysfunction. The influ- ence of higher centres and particularly input from the mesial frontal lobes is thought to be important in modulating the activity of the pontine micturition centres and there is probably also input from other suprapontine regions although these have been less clearly defined. Thus any lesion between 12 Fowler J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.60.1.6 on 1 January 1996. Downloaded from the frontal lobes and the sacral part of the equina has replaced myelography as the inves- spinal cord is likely to result in bladder dys- tigation of choice for imaging this region.51 It function. seems that a congenital malformation of the Because of the relative levels at which the lower spinal cord such as a tethered cord can- innervation of the lower limbs and the bladder not be excluded by a plain radiograph as vari- arise, it is unusual to have a lesion between the ous forms of dysrraphism can occur without pons and the sacral part of the cord giving rise spina bifida. to a neurogenic bladder that does not also produce signs of an upper motor neuron lesion in Pelvic floor neurophysiological investigationis the lower limbs. This is undoubtedly the case There are two conditions in which neurophys- in patients with multiple sclerosis47 but it also iological investigations can disclose an abnor- seems to hold for most other instances of mality that might not otherwise be evident. spinal abnormality unless the lesion is very If there are any other neurological features small and intramedullary. A predictable such as parkinsonism, cerebellar ataxia, pos- exception to this rule might be expected from a tural hypotension, or symptoms suggesting conus or cauda equina lesion affecting only laryngeal stridor, a diagnosis of multiple sys- S2-S4. It seems, however, that even with such tem atrophy should be considered.52 Sphincter extreme caudal lesions there are usually neuro- EMG has proved a valuable test in detecting logical abnormalities in the lower limbs and this disorder by showing pronounced changes foot deformities may be present if the problem of denervation and reinnervation in the motor has been of long duration. units (see earlier). Brain stem or pontine abnormalities giving In young women with bladder disturbance rise to bladder dysfunction often cause other but no other convincing neurological deficit, neurological deficits but occasionally a lesion EMG of the urethral sphincter may show the can be sufficiently dorsal and discrete to pro- myotonic-like activity, decelerating bursts, and duce predominantly a defect of bladder func- complex repetitive discharges described ear- tion.48 An internuclear ophthalmoplegia is a lier.12 Even if sphincter EMG is not available, frequent additional sign, due presumably to in a young woman with urinary retention sim- the proximity of the median longitudinal fasci- ply indicating an absence of spinal cord signs culus. on clinical examination makes a diagnosis of The contribution of suprapontine disease to multiple sclerosis, a condition otherwise likely neurogenic bladder dysfunction, with the to be considered as the cause, highly improba- exception of areas in the frontal lobes, is ble. poorly defined. Patients with incontinence due to lesions of the frontal lobe usually have pro- found neuropsychological impairment includ- Conclusion ing a change of personality but are not The difficulty that neurologists have had with indifferent to their incontinence unless there investigating the neurogenic bladder stems has been extensive frontal lobe damage.4' from a combination of factors: the range of pre- Hydrocephalus probably causes bladder dys- senting symptoms is limited to either inconti- function by pressure effects from the dis- nence or retention, it is not possible to examine tended lateral ventricles on the frontal the bladder clinically, and the impression that http://jnnp.bmj.com/ regions. 501 urodynamics may prove a "diagnosis" has The neurologist may be asked if a patient's obscured the fact that there are many bladder peripheral neuropathy is responsible for blad- disorders of unknown cause. Finally there has der dysfunction. Many forms of neuropathy been the neurologists' reluctance to become are length dependent, the maximum deficit involved in the management of incontinence. being evident in the longest fibres whereas the In bladder dysfunction established neurological

nerve fibres to the bladder are comparatively disease should be regarded as an essentially on September 26, 2021 by guest. Protected copyright. short. For the innervation of the bladder to neurological symptom and investigated and have been affected as part of a generalised managed appropriately. Bladder symptoms are neuropathy there should be clinical evidence among the most treatable of neurological of extensive disease with loss of both knee and deficits and are an unpleasant and troublesome ankle jerks and sensory impairment in small burden for the patient and their carer. fibres to a level well above the ankles. Even if In patients sent from urologists to neurolo- the neuropathy is selective for small fibres gists the emphasis should be on excluding symptomatic bladder involvement occurs rela- spinal cord disease, which can be readily done tively late and only in patients with other pro- by clinical examination. A high index of suspi- found neuropathic symptoms. cion for multiple system atrophy should be maintained for older patients as this is a neu- Imaging of the nervous system rological disease which can present with blad- From the preceding section emphasising the der dysfunction and the patients do not benefit value of clinical examination, it is apparent from urological surgery. that there are regions of the CNS where a 1 Mosso A, Pellacani P. Sur les fonctions de la vessie. lesion can cause bladder symptoms and yet Arc/lives Itali'nnes ds Biologic 1882;i:98-128. produce only minor or equivocal physical 2 Denny-Brown D, Robertson E. On the physiology of mic- is indicated to turition. Brain 1933;56:149-90. signs. Imaging particularly 3 Scott FB, Quesada EM, Cardus C. The use of combined exclude a suprapontine abnormality or a sub- uroflowmetry, cystometry and electromyography in evaluation of neurogenic bladder dysfunction. In: Boyarsky S, sacral cauda equina lesion. Magnetic reso- ed. 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