0022-534 7 /82/1274-0736$02.00
`THE JOURNAL OF UROLOGY
`Copyright© 1982 by The Williams & Wilkins Co.
`
`Vol. 127, April
`Printed in U.S. A.
`
`ABDOMINAL WALL ELECTROMYOGRAPHY: A NONINVASIVE
`TECHNIQUE TO IMPROVE PEDIATRIC URODYNAMIC ACCURACY
`
`STEPHEN A. KOFF AND EVAN J. KASS*
`From the Section of Urology, Department of Surgery, University of Michigan Medical Center and C. S. Mott Children's Hospital,
`Ann Arbor, Michigan
`
`ABSTRACT
`
`Abdominal wall electromyography, using sticky surface patch electrodes placed on the rectus
`abdominus muscles, was used during noninvasive urodynamic studies in 60 children to detect
`straining. Straining, which usually was imperceptible to the examiner, occurred in 64 per cent of
`neurologically normal children. Urodynamics identified detrusor-sphincter dyssynergia during strain(cid:173)
`ing to void but reverted to normal when the same children voided without straining. Because the
`urodynamic findings that characterize detrusor-sphincter dyssynergia are mimicked by straining and
`other common urologic entities, the potential for misdiagnosis is great unless some assessment of
`intra-abdominal pressure is made during neurourologic testing.
`
`With the proliferation of noninvasive pediatric oriented uro(cid:173)
`dynamic techniques has come the suspicion that detrusor(cid:173)
`sphincter incoordination is a major cause of urologic dysfunc(cid:173)
`tion in children. However, because dyssynergia can be mim(cid:173)
`icked by other conditions, such as straining and uninhibited
`detrusor contractions, these conditions must be detected to
`ensure urodynamic accuracy. The usual approach in adults to
`identify straining during voiding and to confirm uninhibited
`bladder contractions during cystometry involves a rectal bal(cid:173)
`loon to measure intra-abdominal pressure. However, in children
`this technique is often incompatible with normal and natural
`micturition, especially when studies are performed while the
`patient is awake. Herein we describe a totally noninvasive
`method for assessing abdominal wall muscular activity using
`electromyography and present our experience with this tech(cid:173)
`nique in the urodynamic study of 60 children with voiding
`disturbances.
`
`MATERIALS AND METHODS
`Urodynamic testing was done in 39 girls and 21 boys between
`6 months and 20 years old (mean age 9.3 years). All patients
`had symptoms of voiding dysfunction, including diurnal enu(cid:173)
`resis, precipitate micturition, incontinence and weak or inter(cid:173)
`rupted streams, and/or recurrent urinary tract infections. Ves(cid:173)
`icoureteral reflux was present in 16 children and 5 had either
`congenital (myelodysplasia) or acquired spinal cord injury.
`A standard urodynamic protocol was adopted to test sepa(cid:173)
`rately bladder filling and emptying. Urotropic drugs were
`stopped 24 hours before investigations and premedication was
`not used. Two disposable infant electrocardiogram electrodes,
`which are pre-jelled and self-adhering, are placed perianally in
`approximately the 10 and 2 o'clock positions. 1 Two similar adult
`electrocardiogram electrodes are placed on the anterior abdom(cid:173)
`inal wall over the lower rectus abdominis muscles, and a third
`reference electrode is placed on the lateral abdominal wall. In
`some older patients hair must be removed to afford better
`electrode adherence. The patient is then asked to cough, strain
`down and squeeze the perineum to confirm satisfactory elec(cid:173)
`trode placement and recording. In addition to recording abdom(cid:173)
`inal wall muscular activity, the abdominal electrodes also mon(cid:173)
`itor electrocardiogram activity, which is easily distinguished
`from the electromyographic tracing. Next, the child is in-
`
`Accepted for publication July 1, 1981.
`Read at annual meeting of American Urological Association, Boston,
`Massachusetts, May 10-14, 1981.
`* Current address: Children's Hospital National Medical Center, 111
`Michigan Ave., N. W., Washington, D. C. 20010.
`
`structed to void into the uroflowmeter, t either standing or
`sitting, with simultaneous recording of electromyographic activ(cid:173)
`ity of the abdominal and perineal muscles as well as the uroflow
`rate on a TECA TE4 multichannel recording electromyograph.:j:
`If straining, evidenced by increased abdominal wall electromy(cid:173)
`ographic activity, is noted during voiding, the child is asked to
`stop voiding and to try again to void without straining (fig. 1).
`Upon completion of the voiding study the patient is trans(cid:173)
`ferred with electrodes in place to an examining table and a lOF
`urethral catheter is inserted in the bladder. With a carbon
`dioxide cystometer§ and the recording electromyograph, com(cid:173)
`bined cystometry, and perinea! and abdominal wall electro(cid:173)
`myography is performed. To test for uninhibited contractions
`the patient is specifically instructed not to void during bladder
`filling. After completing the cystometric studies, those patients
`in whom the voiding examination was either incomplete or
`associated with straining are restudied by uroflowmetry and
`electromyography after filling the bladder with saline. At the
`conclusion of urodynamic testing each patient is anesthetized
`for cystoscopy.
`To assess the significance of increased abdominal wall elec(cid:173)
`tromyographic activity 7 children were studied simultaneously
`with a rectal balloon to monitor intra-abdominal pressures
`during urodynamic testing.
`
`RESULTS
`The surface patch electrodes were applied successfully in all
`cases and, in each instance, voluntary contraction of the peri(cid:173)
`nea! and abdominal wall muscles confirmed electrode position
`and produced an increase in the respective electromyographic
`activities. Differences in the pattern of muscular activation
`were observed during Valsalva type maneuvers (such as cough(cid:173)
`ing and bearing down), which usually produced a simultaneous
`increase in perineal and abdominal wall electromyographic
`activity compared to perineal tightening, which typically caused
`only a response in perineal electromyography. In children stud(cid:173)
`ied simultaneously with rectal balloon pressure measurements
`elevation in rectal pressure was observed in all cases whenever
`abdominal electromyography indicated activation of the ab(cid:173)
`dominal wall musculature (fig. 2).
`In tests of bladder emptying 56 of 60 children (93 per cent)
`voided successfully into the uroflowmeter on ~l occasions. Of
`23 children who voided to completion (residual urine <25 cc)
`t American Medical Systems Model N7520B, Minneapolis, Minne(cid:173)
`sota. t TECA Corp., White Plains, New York.
`§ Modern Controls, Inc., Minneapolis, Minnesota.
`
`736
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`Petitioner - Avation Medical, Inc.
`Ex. 1037, p. 736
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