ELECTROMYOGRAPHY OF URETHRAL SPHINCTER IN WOMEN WITH URINARY RETENTION

Saturday 28 June 1986

urinary retention. EMG with a concentric-needle electrode

ELECTROMYOGRAPHY OF URETHRAL SPHINCTER IN WOMEN WITH URINARY RETENTION

CLARE J. FOWLER

R. S. KIRBY

Departments of Clinical Neurophysiology and Urology, Middlesex Hospital, London W1 Concentric-needle electromyography (EMG) of the urethral sphincter muscle was carried out in 48 women with urinary retention. Changes in motor unit configuration indicating reinnervation were found in 16 women, and myotonic-like EMG activity, which may impair urethral relaxation, in 19 women. Sphincter EMG was normal in 13 cases. The finding of a significant abnormality in 72% of cases calls into question the validity of the commonly applied diagnosis of psychogenic urinary retention.

Summary

Introduction ALTHOUGH

urinary retention

in

women

is

not

uncommon, there has been little useful research into the none of the various theories proposed to for it has gained general acceptance. It used to be thought that retention in women resulted from outflow obstruction caused by hyperplasia of urethral glands, a disorder analogous to prostatic hypertrophy in men.102 Histological studies, however, showed no pathology of these glands, and instead it was postulated that urethral obstruction might occur at the level of the bladder neck 2,3 Another suggestion was that the disorder was caused by a cauda equina lesion resulting from a silent prolapse of a lumbar intervertebral disc.4 Spasticity of the striated muscle of the urethral sphincter has also been implicated,sbut no neurophysiological explanation was proposed to account for this localised abnormality of muscle function. The normal findings on cystoscopy and absence of associated’ neurological abnormalities have led some workers to suggest that urinary retention is psychogenic.’-" This view has gained support, and now women with urinary retention may be labelled as having "psychogenic retention" in the absence of an alternative diagnosis. To investigate this disorder, we used conventional electromyographic (EMG) techniques to examine the striated muscle of the urethral sphincter in women with

disorder, and account

a

allows examination of individual motor units, from which reinnervation may be recognised. If there has been an incomplete lesion affecting the nerve supply of a muscle, collateral innervation can occur; axons from intact units sprout to innervate adjacent muscle fibres that have lost their nerve supply. As a result of this process, motor units develop more complex waveforms, which are polyphasic and of long duration initially, then become compact and increase in amplitude as the nerve sprouts mature. Concentric-needle EMG of the urethral sphincter muscle tests the integrity of the motor innervation that arises from the S2-S4 spinal levels.9,10 In addition, it can detect a type of activity associated with an impairment of relaxation of the striated muscle of the urethral sphincter, which we have called decelerating bursts and complex repetitive discharges.ll,12 Patients and Methods Previous studies of control subjects have allowed characterisation of EMG parameters of the urethral sphincter for this laboratory. 13 Our results were comparable with other control EMG data for this muscle.1O,14,1s The normal urethral sphincter in both sexes displays constant tonic activity at rest, with three to four motor units recorded at each site by a concentric-needle electrode. Individual motor unit analysis has shown that up to 7% of units may have polyphasic waveforms14,ls and that the motor units from the sphincter are of smaller amplitude and shorter duration than those recorded from skeletal muscle. 96% of units were less than 2.0 mV amplitude and less than 6-0 ms duration." 48 women with long-standing urinary retention were studied. There were overt neurological abnormalities in 3 patients, but in the others no diagnosis had been made before this study. EMG of the striated muscle of the urethral sphincter was recorded with a concentric-needle electrode introduced percutaneously into the muscle. The patient lay with her hips flexed and abducted, and the electrode (tip diameter 0-45 mm, length 30 mm) was inserted 1 cm lateral to the urethral meatus and guided towards the midline. Audio output of EMG activity aided electrode placement. Once the electrode was correctly sited, the time base of the oscilloscopic display was increased, so that features of individual motor units could be examined. By means of a delay line and signal triggering, ten motor units were analysed. The small size of the muscle limited the number of changes in needle position that could be made. From measurements of duration and amplitude an individual unit was considered to be abnormal if the waveform duration exceeded 6-0 ms or the amplitude 2 mV. A waveform with more than five phase reversals of voltage greater than 100 Jl V was

regarded as polyphasic. 8496

©

1456 DISORDERS ASSOCIATED WITH ABNORMAL MOTOR UNITS

urinary retention, although other symptoms and signs of neurological disease are also usually present. However, damage to the peripheral innervation of the bladder in the pelvis may result in loss of sensation and impairment of detrusor contraction and thus produce urinary retention as

I

an

Results On the basis of the EMG allocated to three groups.

findings,

the

patients

were

Reinnervation In 16 women, individual motor unit analysis showed that than 50% of the motor units were abnormal, being either polyphasic and of long duration, or of increased amplitude. 12 of the patients had had associated disorders that may have led to neural damage in the cauda equina or pelvic nerves (see table). The cause of abnormal motor units in 4 cases was not clear. Myelography in 2 of these patients (both nulliparous) was normal. more

Decelerating Bursts and Complex Repetitive Discharges In 19 women, a prominent finding was a type of spontaneous EMG activity that we have termed decelerating bursts and complex repetitive discharges. Decelerating bursts sound very like myotonic discharges, and complex repetitive discharges produce a buzzing sound. The amount of such activity varied between patients, but in all 19 the activity occurred frequently and spontaneously during the examination. This activity was heard in addition to normal tonic motor unit firing. 11 patients with this type of EMG activity were multiparous or had had pelvic surgery (eg, hysterectomy). Normal Motor Units In 13 women, the motor units in the interference pattern of the tonic EMG activity were normal. Since sphincter EMG was not done as part of a urodynamic assessment, no observations were made on the kinetic activity of the sphincter during attempts to void. 3 patients in this group had associated disorders that could have been related to their

bladder dysfunction (1 fractured femur, 1 Behcet’s syndrome).

procidentia,

1

Discussion Normal micturition follows a sensation of bladder fullness and is achieved by coordinated relaxation of the urethral sphincter and detrusor contraction. This process depends on intact innervation between pontine centres and the bladder, with suprapontine centres effecting voluntary control. In spinal cord lesions, urinary retention results from an interruption of the descending medullary-spinal pathways necessary for the initiation of micturition but is usually associated with other symptoms and signs of cord dysfunction. Cauda equina lesions may likewise result in

isolated symptom.

Urethral-sphincter EMG has proved useful in the recognition of lower motor neuron lesions arising from injury to pelvic nerves. In 16 of the women we studied, the configuration of the individual motor units was abnormal, indicating previous partial damage to the nerve supply to the urethral muscle and subsequent reinnervation. 2 of these women had cauda equina lesions and another severe diabetic neuropathy. 9 had undergone extensive pelvic surgery that was probably the cause of pelvic and pudendal nerve injury.16,17 Urethral-sphincter EMG was valuable in the management of these patients, since it provided positive evidence of nerve damage and thus an explanation for the disorder. The other 4 who showed changes of reinnervation had not undergone pelvic surgery, but occult damage to the pudendal and pelvic nerves could have occurred during childbirth or as a result of repeated abdominal straining.18 In 19 patients, the predominant finding was of decelerating bursts and complex repetitive discharges, which we have suggested may be associated with impairment of sphincter relaxation. 11 We have already reported this type of EMG activity in women with isolated urinary retention and subsequently analysed its electrical properties in detail. 12 These abnormal burst discharges have properties in common with another type of EMG activity known as bizarre high frequency discharges, which have been described in skeletal muscle particularly in association with reinnervation. The discharges are thought to be due to direct ephaptic transmission of depolarising currents, spreading circuitously between muscle fibres ;19 this also appears to happen with decelerating bursts and complex repetitive discharges.12 The activity in skeletal muscles may produce muscle cramps,19 and we suggest that in the small semicircular urethral sphincter muscle, bursts of depolarising activity impair normal relaxation of the muscle. Complete bladder emptying is impeded, which results in an insidious increase in residual volumes and bladder distention, and eventually urinary retention. The pathogenesis of the abnormal burst discharges in the urethral sphincter is as yet unexplained, but it seems unlikely to be secondary to reinnervation, since we have not found the activity in significant amounts in patients with either cauda equina lesions13 or Shy-Drager syndrome,20 in which extensive reinnervation occurs. In the remaining 13 women, urethral EMG was normal. Although this technique demonstrated an abnormality in 72% of women with retention, it does not test spinal or supraspinal micturition pathways. Further studies are in progress to assess these pathways. Until the results of all

investigations have been shown to be normal, a diagnosis of psychogenic urinary retention should not be such

entertained. We thank Mr R. T. Turner-Warwick, Mr E. Milroy, Mr W. Hendry, Mr P. Worth, Prof J. Blandy, Mr J. Osborne, and Mr J. Steele, for permission to study their patients, and Sir Roger Bannister, Dr M. Harrison, Dr M. Swash, and Dr Morgan-Hughes, for referring patients.

Correspondence should be addressed to C. J. F., Reta Lila Weston Institute of Neurological Studies, Middlesex Hospital Medical School, London WIN 8AA.

1457

PERCUTANEOUS LASER THERMAL ANGIOPLASTY: INITIAL CLINICAL RESULTS WITH A LASER PROBE IN TOTAL PERIPHERAL ARTERY OCCLUSIONS D. C. CUMBERLAND D. I. TAYLER C. L. WELSH J. K. GUBEN1

T. A. SANBORN1 D. J. MOORE A. J. GREENFIELD1 T. J. RYAN1

Northern General Hospital, Sheffield, UK; and Boston University Medical Center, Boston, Massachusetts, USA1

A metal-tipped laser fibre was used Summary during percutaneous angioplasty of femoral/popliteal or iliac artery occlusions in 56 patients. Primary success was achieved in 50 (89%) of these total occlusions, providing a channel for subsequent balloon dilatation. Before the procedure, 18 lesions had been judged

untreatable by conventional angioplasty and four of the six failures were in these. Complications directly attributable to the laser probe were one case of vessel perforation and two cases of entry into vessel walls; these had no sequelae. Other acute complications were a distal thrombosis in a non-heparinised patient, requiring local streptokinase treatment, and two reocclusions and one transient peripheral embolic episode in the first 24 hours. The laser probe technique has potential for increasing the proportion of patients suitable for

angioplasty. Introduction PERCUTANEOUS balloon angioplasty is an established technique for treating selected patients with arterial disease. Ideally, it is applied to isolated stenoses. It can also be used in some chronic total occlusions but a major limiting factor is the difficulty of traversing them by guidewires and catheters. Success rates in highly

selected total occlusions in the femoral/popliteal segment are about 75%,l,2 compared with over 90% for stenoses.1 In coronary occlusions, angioplasty is unlikely to succeed if the occlusion has been present for more than about two months.3 Atheroma and thrombus can be vaporised with laser energy,4 but experiments in animals have been beset by a high incidence of vessel wall perforation,s whatever the wavelength or delivery system used.6 The very limited

1. Folson AI. The female 2. Emmett JL, Hutchins

urethra. JAMA 1931; 97: 1345-51. SPR, McDonald JR. The treatment of urinary retention in women by transurethral resection. J Urol 1950; 63: 1031-42. 3. Braasch WF, Thompson GJ. Treatment of the atonic bladder. Surg Gynecol Obstet

1935; 61: 379-84. 4. Emmett JL, Love JG. Vesical dysfunction caused by protruded lumbar disk. J Urol 1971; 105: 86-91. 5. Raz S, Smith RB. External sphincter spasticity syndrome in female patients. J Urol 1976; 115: 443-46. 6. Larsen JW, Swenson WM, Utz DC, Steinhilber RM. Psychogenic urinary retention in women. JAMA 1963; 184: 697-700. 7. Margolis GJ. A review of literature on psychogenic urinary retention. J Urol 1965; 94: 257-58. 8. Allen TD. Psychogenic urinary retention. South Med J 1972; 65: 302-04. 9. Jesel M, Isch-Treussard C, Isch F. Electromyography of the striated muscle of anal and urethral sphincters. In: Desmedt JE ed. New developments in electromyography and clinical neurophysiology, vol 2. Basel: Karger, 1973: 421-32. 10. Blaivas JG, Labib KB, Bauer SB, Retik AB. A new approach to electromyography of the external urethral sphincter. J Urol 1977; 117: 773-77. 11. Fowler CJ, Kirby RS. Abnormal electromyographic activity (decelerating burst and complex repetitive discharges) in the striated muscle of the urethral sphincter in 5

clinical experience with percutaneous laser angioplasty suggests the same drawback. In a series of 15 patients undergoing peripheral angioplasty with argon laser energy, there were two perforations, despite verification that the fibre was within the lumen;7 and in another series the perforation rate was three out of 16.8 In neither series was the use of laser found to confer any benefit over conventional methods.7.8 In a report of in-vitro experiments with Nd-YAG energy,9 Geschwind et al9 mentioned production of a narrow channel in two femoral occlusions without complication, but they gave no details. Lately, a rounded metal-tipped laser fibre, the laser probe, has been developed (Trimedyne Inc, Santa Ana, California). This converts all the laser energy to heat, providing an operating temperature of about 400° C at the end of the fibre. In a rabbit model, thermal angioplasty with the laser probe has been found to produce a larger lumen with less risk of perforation than a bare laser fibre.1O We report here our combined clinical experience with the laser probe in patients undergoing percutaneous angioplasty for total peripheral artery occlusions.

Patients 56

and Methods

patients with total peripheral artery occlusions consented

as part of The indication for angioplasty was intermittent claudication in 41 and rest pain or gangrene in 15. There were 53 femoral/popliteal occlusions of 1-35 cm length (mean 8 cm) and 3 iliac occlusions, 4-6 cm long. Ethical committee approval, and in the case of the Boston patients approval of the US Food and Drug Administration, had been obtained. An arterial sheath was placed antegradely in the ipsilateral femoral artery by percutaneous catheterisation under local anaesthesia, and 5000 U of heparin were given intra-arterially. From previous assessment of the angiogram and/or by gentle probing at the proximal limit of the occlusion with a guide wire (without an attempt to cross the occlusion), the lesions were subjectively classified as "easy" (17) or "difficult" (21) to cross by conventional angioplasty methods. 18 occlusions were classified as "impossible" either because previous angioplasty attempts had failed (11) or because they were deemed anatomically unsuitable for conventional angioplasty (for example, extension into the tibial vessels, 7). The system included a laser probe, connected to a 14 watt argon laser source via a 300 micron core fibre, that was passed

to

undergo percutaneous laser thermal angioplasty

their balloon

angioplasty procedure.

with persisting urinary retention. Br J Urol 1985; 57: 69-70. CJ, Kirby RS, Harrison MJG. Decelerating burst and complex repetitive discharges m the striated muscle of the urethral sphincter, associated with urinary retention in women. J Neurol Neurosurg Psychiatry 1985; 48: 1004-09. 13. Fowler CJ, Kirby RS, Harrison MJG, Milroy EJG, Turner-Warwick R. Individual motor unit analysis in the diagnosis of disorders of urethral sphincter innervation. J Neurol Neurosurg Psychiatry 1984; 47: 637-41. 14. Chantraine A. Electromyographie des sphincters stries uretral et anal humains. Etude descriptive et analytique. Rev Neurol 1966; 115: 396-403. 15. Vodusek DB, Light JK. The motor nerve supply of the external urethral sphincter muscles: an electrophysiologic study. Neurourol Urodynam 1883; 2: 192-200. 16. Low JA, Mauger OM, Carmichael JA. The effect of Wertheim hysterectomy on bladder and urethral function. Am J Obstet Gynecol 1981; 139: 826-34. 17. Blaivas JG, Babalias GA. Characteristics of neural injury after abdominoperineal resection. J Urol 1983; 129: 84-87. 18. Swash M, Henry MM, Snooks SJ. Unifying concept of pelvic floor disorders and incontinence. J R Soc Med 1985; 78: 906-11. 19. Trontelj J, Stalberg E. Bizarre repetitive discharges recorded with single fibre EMG. J Neurol Neurosurg Psychiatry 1983; 46: 310-16. 20. Kirby R, Fowler CJ, Gosling J, Bannister R. Urethro-vesical dysfunction in progressive autonomic failure with multiple system atrophy. J Neurol Neurosurg Psychiatry 1986; 49: 554-62. women

12. Fowler