Electrical Stimulation of the urinary dysfunctionGuy de
Bisschop, MD, Eric de Bisschop, MD, André Mamberti-Dias, PhT.
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Received 4 april 2002 | ||||||||||||||||||||||||||||||||||||||||||
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Electrical stimulation is of great importance and is justified as the treatment of urinary dysfunction [1]. Unfortunately parameters mentioned by different authors often contribute to anarchical therapeutic techniques. Four types of incontinence are defined : urge, stress, reflex and overflow. Physiological effects are optimal at different stimulation parameters [2]. Stimulation parameters 1. Electrodes Two types are available: a.
Intra-vaginal or intra-anal electrodes: The device consists of a plastic probe with two embedded ring
electrodes. ("Sugar") We insist on the fact that one of the most important factors of success lies in the conception and quality of the electrodes. 2. Current Several types of electrical currents are available to treat urinary dysfunction: a. Pulses Monophasic, biphasic, alternating. Experiments and clinical investigations indicate that rectangular alternating pulses are most effective [3] (Fig. 1)
We have been using alternating medium frequency current modulated in low frequency for a long time (Fig. 2) [4-5]. A carrier frequency around 4000 Hz is modulated, exogenously or endogenously.
The amplitude modulation results in a beat frequency between 5 to 70 bps (Fig. 3).
Two modalities are available:
We developed this type of current for perineological indications. 20 ms bursts of 8 – 10 biphasic pulses (0,3 ms width) are generated each at 2 – 4 Hz (Fig. 6).
The clinical effect is that electrical discharges occur at lower amplitude settings, and thus tend to provide a more confortable sensation to the patient. This type of stimulation has an hypogastric effect on the bladder accomplished by a beta-adrenergic depression of the detrusor smooth muscle and an alpha-adrenergic depression on the transmission in vesical parasympathetic ganglia. This type of current is particularly indicated in detrusor
instability. A correct choice of stimulation frequency is very important. For single pulses and medium frequency currents a stimulation frequency of 10 Hz or beats is most suitable for bladder inhibition Urethral closure and weak muscle stimulation are most effective at frequencies around 50-70 Hz or bps [3]. Electrical treatment of urinary dysfunction 1. Detrusor instability - Urge incontinence Activation of a pudendal-pelvic reflex to either depress or totally eliminate unhinibited detrusor contraction [6-7]. The technique involves vaginal or pelvic stimulation by alternating pulses or medium frequency currents at a frequency of 5-10 Hz, or 2-4 Hz bursts. Two kinds of electrodes are available: - An intra-vaginal electrode is most suitable for bladder inhibition. Surface electrodes can be applied in different manners: a. Interferential quadripolar method - Two electrodes are placed symmetrically on the abdomen above the inguinal ligament, 3 cm
apart.
Alternating pulses, medium frequency
currents, uroflash.
A dermatome is considered to be the cutaneous region that is innervated by one spinal nerve though both of its rami. The visceral and the somatic afferents are connected with autonomic and somatic efferents at the segmental level of the the spinal cord (Fig. 9) [8-9].
A cutaneo-visceral reflex is based on the segmental afferents of the receptors in the skin with the autonomic efferents to the detrusor [10-11]. Considering dermatomal mapping, electrostimulation of the areas L3, L4, L5, S1, S2 successfully inhibit detrusor activity
(Fig. 10, 11, 12) [12-13-14-15].
Electrical stimulation can be used in cases of myogenic incontinence, weakness of periurethral muscles, damage to the peripheral nerve supply of the striated muscles of the pelvic floor. The effect of the electromyostimulation is to induce contraction of striated pelvic floor musculature, including the external urethral sphincter (Fig. 5, 9, 13, 14, 15) [16-17]. Neuromuscular stimulation improves muscular strength and enhances circulation in the contracting muscle [8]. These effects are particularly interesting in the framework of pelvic floor musculature pathology.
Electrodes · Vaginal or anal probe Current · Alternating pulses:
Frequency: 50 Hz To ensure the muscle does not fatigue excessively the electrical stimulation may be automatically turned “On” (contraction) and “Off” (relaxation) [8]. 3. Postpartum 1. Muscular damage Delivery may be a factor of developing anatomic alteration of the muscle levator ani, particularly the muscle puborectalis. That leads to a pelvic floor muscular weakness, without electrical sign of denervation. Local ischemia, stretching and compression, microtraumas with microhematomas, induce a decrease of contractile power, and a muscular teary if the elasticity-limit is exceeded. Without a specific treatment, fibrosis of muscular tissue may develop, that is a definitive loss of some muscular fibers. Concentric needle electromyography of perineal muscles (levator ani, bulbocavernosus, sphincter) reveals a high percentage of polyphasic potentials with a reduction in the mean duration of the motor unit potentials, that reflects a loss of muscles fibres within the motor unit. However these signs are transitory. Fibrillation potentials are sometimes present. In this type of damage they don’t represent an axonal denervation but an isolated part of a broken muscle-cell (myogenic fibrillation). (Fig. 16)
Pudendal nerve and its branches are composed of myelinated and unmyelinated nerve fibers. They are susceptible to be stretched or compressed [18-19]. The “primum movens of damaging” is at first vascular which causes an impairment of the intraneuronal microcirculation and formation of intraneural œdema. These disturbances lead to physiopathologic changes in nerve function. A demyelinisation occurs with a slowing of the nerve conduction, which is not a denervation [20-21]. However disturbances are not identical in the different nerve fibers composing the pudendal nerve. Thus, fiber velocities are not decreased with the same importance that induces asynchrone nerve conductions and results in a muscular weakness. This decrease of the volontary muscle contraction could be falsy interpreted as a denervation by a non experimented clinician. Nerve function recovers quickly when the remyelinisation is effective. Electrostimulation helps resynchronizing of the different nerve fibers. The function of nerve fibers is not only to transmit impulses but also to transfer biological material from the neuronic soma to end organs (striated muscles in the present case). It may be blocked by ischemia, compression or stretching, that compromises the trophicity of muscle fibres. Moreover damage fibers are oversensitive and can give rise to a detrusor ectopic activity. Nerve function recovers in some weeks, if a specific electrotherapy has been applied. Two types of urinary incontinence may be distinguished during the postpartum, and me be present in the same time: Electrological findings are characterized by signs of minor importance : mild increase of polyphasic potentiels, normal duration of motor unit potentials (MUP), possibility of slight slowing of the distal pudendal nerve conduction, no sign of axonal denervation. 3. To suming up During postpartum the effector organ is more dysfunctioning than the motor command. 4. When starting electrostimulation? Electrostimulation may be applied one month – six weeks after delivery, not later. It is necessary to recall the old adage of the french electrologists: “one day lost, a week lost; one week lost, one month lost”.
Before electrostimulation complete neurourological investigations are necessary: Neurourological functional investigations are of primordial importance to explore pelvic floor dysfunction and the intricated system of control. They are most adapted for choosing adequate therapy [22]. Diagnosis can only be made by both urodynamical (UD) and electrophysiological (EP) methods, which must be considered as a whole (UD-EP). These two types of investigation obligatory must be executed by the same physician and in the same time. Disregarding this necessary procedure is an absurdity and may lead to diagnosis errors and therapeutic faults. Pathophysiology of vesicosphincterian troubles and pelviperineal pain is often complex and needs a global consideration. For diagnosis the major problem is based upon a standardisation of UD-EP techniques. There are different categories of ætiological symptoms affecting the genitourinary system : gynaecologic, urologic, neurologic, idiopathic, functional… Urodynamic tests can identify either vesical, urethral and/or vesicosphincterian dysfunction [23] However it is necessary to consider two categories of disease affecting the genitourinary system : Those affecting the central nervous system (Parkinson’s disease, spinal cord injury, multiple sclerosis) and those affecting the peripheral innervation of the bladder, urethral and anal sphincter, pelvic floor musculature, including autonomic innervation. For these reasons urodynamic exploration imperatively has to be coupled to electrodiagnosis methods [24]: - Concentric needle EMG of the perineal muscles (levator ani, urethral sphincter,
bulbocavernosus) The different elements of the perineum are interdependent and their dysfunction can interfere, even to the lumboscral spine. Pelvic floor dysfunction evolves in the framework of the correlative pathology. Choice of the type of therapy, physical, medical, surgical, depends in a great part of the results of UD-EP investigations, which can play a warning role for a surgical decision. Conclusion Electrical stimulation is an effective therapeutic option for urinary incontinence. Furthermore it is a safe procedure with no serious reported adverse effects. But to be successful, it necessary to take into account electrical stimulation parameters, low frequency for bladder inhibition, higher frequency for urethral closure dysfunction and weakening of pelvic floor musculature. During postpartum stimulation has to be started early after delivery (4 or 6 weeks). Choice of the types and parameters of stimulation depends of neurourological investigations. At the beginning, treatments must be applied by perfectly educated physical therapists or midwives, and later home treatments [31-32] have to be supervised by the sames. References | ||||||||||||||||||||||||||||||||||||||||||
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