referring to fig1 , a system and apparatus in accordance with an embodiment of the present invention , for treating fecal incontinence , are illustrated in schematic form . the system includes an apparatus comprising an implantable stimulator 1 and a device comprising contractile tissue 2 which is arranged to be stimulated by a signal that is generated by the stimulator 1 and , in this embodiment , applied to the contractile tissue 2 via an electrode 3 conductively connected between the stimulator 1 and contractile tissue 2 . in this embodiment , the stimulator 1 includes a signal generator for producing a pulsatile signal which is housed in a bio - compatible housing 4 . the stimulator 1 will be described in more detail later . the contractile tissue 2 in this embodiment is formed into a sphincter which is implanted about the fecal sphincter region , in this embodiment proximate to the anus . in fig1 , the external fecal sphincter is designated by reference numeral 5 and the internal fecal sphincter by reference numeral 6 . failure of operation of the external and / or internal fecal sphincters perhaps because of nerve damage , or other reason ) have led to fecal incontinence in this patient . stimulation of the contractile tissue sphincter 2 , in operation , causes the contractile tissue 2 to contract and maintain closure of the fecal canal 7 , maintaining fecal continence . in this embodiment , the contractile tissue is smooth muscle tissue . the smooth muscle tissue may be obtained from elsewhere in the body , formed into a sphincter and surgically implanted . alternatively , the smooth muscle tissue may be grown from smooth muscle stem cells and / or proliferative smooth muscle cells . alternatively , the smooth muscle tissue may be transplanted smooth muscle tissue augmented by smooth muscle stem cells and / or proliferative smooth muscle cells . alternatively , the smooth muscle tissue may be the tissue of the internal fecal sphincter . international patent application no : pct / 2006 / 001301 , referred to above , discloses augmentation of contractile tissue using proliferative smooth muscle cells or smooth muscle stem cells . growth , maturation and stability of the tissue may be influenced by growth factors ( trophic and / or neurotrophic factors ) that are a component of the treatment . smooth muscle may be taken from anywhere or grown ( as discussed above ). in an embodiment the smooth muscle may be taken from the smooth muscle of the bladder and transplanted about the urethra , with its circulation intact . alternatively , the muscle is venous smooth muscle , anococcygeus smooth muscle or terminal ileum transplanted as a segment devoid of mucosa and having its circulation intact . a further alternative is the dartos smooth muscle from the scrotum or a portion of the vagina or labia . in an embodiment , smooth muscle may be taken as a free graft . in this case , the tissue is separated from its normal circulation and becomes vascularised by ingrowth of blood vessels at the site of implant . the stimulator 1 includes a signal generator arranged to provide a stimulation signal for stimulating the smooth muscle sphincter 2 . a lead 8 extends from the stimulator 1 to the electrode 3 at the smooth muscle sphincter 2 , for providing the stimulation signal 2 to the smooth muscle sphincter 2 . the stimulation signal may be a signal of frequency and amplitude determined to maintain contraction of the smooth muscle sphincter 2 to facilitate continence . the stimulator 1 may also be arranged to produce a further electrical signal to stimulate the sphincter 2 to relax , to enable the patient to defecate . as an alternative to a further electrical signal , the stimulator 1 may be arranged to stop producing any electrical signal and it is the absence of the signal that causes the sphincter 2 to relax . in this embodiment , the stimulator 1 is arranged to have the stimulation signal varied under control of the patient by way of an external controller . fig2 shows an alternative embodiment . in the fig2 drawing , the same reference numerals have been used as in fig1 for equivalent components . those components have the same function as in fig1 and no further description will be given here . in the fig2 embodiment , the contractile tissue sphincter 2 is placed further up the colorectum , in the abdomino - pelvic region , away from the anus . this different positioning may be used if surgically convenient . in some cases , this different position may be utilised where there is some damage to the anus . such damage may occur , for example , from the former use of prosthesis in an attempt to correct the incontinence problem . there does not have to be any damage to the anus for this alternative positioning to be used . in a further alternative embodiment , the sphincter 2 may be positioned about the external fecal sphincter . in a further alternative embodiment , a neosphincter may not be utilised , instead stimulation may be applied directly to the internal fecal sphincter 6 . the stimulator 1 is shown in more detail in fig3 . in this embodiment , a signal generator that is arranged to provide the electrical signal for stimulation of the sphincter 2 is in the form of a control unit 9 and stimulus driver 10 . the control unit 9 encodes the stimulus and provides a signal to the stimulus driver 10 which provides the stimulation signal at output 16 . the output 16 outputs to conductor 32 and to one or more electrodes 3 . in this embodiment , the control unit 9 and stimulus driver 10 form , together with a demodulator 18 , a processing unit for generating the stimulation signal ( s ) at output 16 . the demodulator 18 is arranged to demodulate a signal received by transceiver 15 . an external control unit and external programmer unit ( both to be described later ) are able to communicate via the transceiver 15 with the processing unit 14 in order to control application of stimuli and / or vary the stimuli . in addition , as described in more detail later , the processing unit 14 may transmit , via control unit 9 , demodulator 18 and transceiver 15 , signals to the control unit or programmer unit . the transmitted signals may deliver telemetry information indicative of parameters of the stimulator , for the purposes of calibration and control . the entire stimulator 1 ( including components 14 and 15 ), is enclosed in a housing which includes a casing made from a bio - compatible material , such as titanium , silicone polymer or other acceptable materials , or combinations of materials , including , but not limited to inert materials . the frequency of the rf signal for transmission and reception by the transceiver 15 may depend on the material of the casing of the stimulator . fig4 shows a system in accordance with an embodiment of the present invention . the system incorporates the implanted stimulator 1 , with transceiver 15 . the electrode ( s ) 3 is shown schematically together with cable 32 . the system also comprises an external controller 17 which includes a transmitter 11 . the controller 17 is intended for operation by a patient with the stimulator implanted , for control of the stimulator 1 . the controller 17 includes an actuator ( such as a button , not shown ) operable by the patient to selectively send signals to the implanted stimulator 1 , for control of the stimulation signals being sent to the electrode ( s ) 3 . in one embodiment , the stimulator is “ fail safe ”. unless a signal is received from the controller 17 , the stimulator produces a signal which maintains tone in the smooth muscle implant 2 , maintaining fecal continence . when the patient wishes to defecate , the patient actuates the controller 17 to send , via the transmitter 11 , a signal to the stimulator 1 . in response to receiving the signal , the control unit 9 operates to turn the stimulating signal off causing the sphincter 2 to relax and allow the patient to defecate . the controller 17 may also be arranged to provide a further signal under patient control , once the patient has finished defecating , the further signal causing stimulator 1 to resume providing the stimulation signals to the electrode ( s ) 3 . in “ fail safe ” mode , if the further signal is not produced , the stimulator may resume providing the stimulation signal to the electrode ( s ) 3 after a predetermined period of time . the stimulation signal 16 provided to contract the smooth muscle sphincter 2 is selected so as to provide a substantially continuous tone in the sphincter 1 . a generally rectangular and symmetrically biphasic pulse may be suitable for this . the signal has a substantially constant current less than or equal to 50 ma , 15 ma , 10 ma , or 5 ma , and in some preferred embodiments may be in the order of 4 ma , 8 ma , 12 ma , or 15 ma . stimulation pulse frequency provided to sphincter 1 is in the range of 0 . 1 hz to 5 hz , 0 . 2 hz to 4 . 0 hz . 0 . 25 hz to 3 . 0 hz , 1 hz to 3 . 0 hz , 1 . 5 hz to 3 hz , 1 . 75 hz to 2 . 5 hz , or a 0 . 25 hz to 2 . 25 hz , and in one embodiment , is 1 hz , 2 hz , 2 . 5 hz or 3 hz . stimulation phase width of each phase is in the range of 0 . 05 ms to 2 . 0 ms , 0 . 1 ms to 1 . 5 ms , 0 . 2 ms to 1 ms , 0 . 25 ms to 0 . 75 ms , and in one embodiment is 0 . 2 ms , 0 . 4 ms , 0 . 5 ms or 1 ms . the stimulator is current regulated , and accordingly the stimulation voltage will vary with the resistance of the muscle tissue between the electrodes . typical values for the voltage are between 0 . 1 and 15 volts , 0 . 2 and 12 volts , 0 . 5 and 12 volts , 0 . 5 and 10 volts , or 0 . 5 and 7 . 5 volts . in one embodiment , the voltage is 2 . 5 volts , 5 volts , 7 . 5 volts or 10 volts . either a current source ( voltage limited ) or a voltage source ( current limited ) stimulator may be used . it is also possible to use an asymmetric biphasic pulse , in which , for example , the first phase is shorter in duration than the second phase . fig5 shows a system in accordance with an embodiment of the present invention , including a programmer unit 13 which may be utilised by a physician to set and adjust parameters of the implanted stimulator 1 . the programmer unit is arranged for communication with the stimulator via transceiver 11 , and may comprise a computing device . the control unit 9 is also arranged to transmit stimulator telemetry information indicative of one or more of the parameters of the stimulator 1 , for detection by the programmer 13 via transceiver 1 . the programmer unit 13 can therefore determine parameters of the stimulator from telemetry information and can adjust the parameters by transmitting control signals to the stimulator 1 . the signal from the programmer may be able to selectively vary the output current , shape , frequency and / or pulse width of the stimulation signal ( s ). in operation , a physician adjusts parameters of the stimulation signal ( s ). the physician will note feedback from the patient as to the effect of the stimulus on fecal continence control , and may subsequently re - adjust the parameters until the stimulation is optimum . for example , patient perceived feedback may be used to set the maximum stimulation threshold of the smooth muscle sphincter . in the above - described embodiments , signals between the controller or programmer and the stimulator are rf signals . other types of transmission media other than rf may be used . for example , microwave signals may be used for transmission , optical signals may be used , and in another embodiment magnetic transmission may be used . magnetic transmission may be used for the controller 17 to cause the stimulator to stop producing stimulation signals and therefore allow the patient to defecate . in this embodiment , the controller 17 may be a simple magnet which , when passed over a magnetic receiver of the stimulator 1 , results in the stimulator ceasing to provide stimulation signals for contracting the sphincter . in the above embodiments , any suitable electrode ( s ) may be utilised to stimulate the implant 2 . for example , button electrodes , cuff electrodes or any other suitable electrode may be utilised . in embodiments , an electrode arrangement such as a disclosed in pct / au / 20054 / 001698 may be utilised . fig6 illustrates an embodiment of the present invention where a “ peg ” electrode 3 a such as disclosed in pct / au20054 / 001698 is utilised to transmit signals to the implant 2 from the stimulator 1 . in fig6 , the same reference numerals as used in previous embodiments have been utilised to designate similar components , and no further description will be given here of these components . the electrode 3 a will now be described in more detail . the electrode comprises a number of components . these include an electrode cover 100 ( shown in most detail in fig1 through 18 ). the components also include an electrode shroud ( shown in best detail in fig1 through 13 ) and also an electrode lead 102 ( shown in fig7 , 8 & amp ; 9 , together with the other components of the electrode arrangement ). in this embodiment first and second electrode elements are formed by the electrode cover 100 , which includes insulating elements 103 , 104 extending from a base 105 . the insulating extending elements 103 , 104 are formed with a slot 106 , 107 , respectively , extending substantially along the length of the extending elements 103 , 104 . when the electrode arrangement is assembled , platinum foil electrodes 108 , 109 ( fig7 ) are placed on the outer surfaces of the elements of the elements 103 , 104 so that they are insulated from the gap 110 formed between the elements 103 , 104 apart from the slots 106 , 107 , which expose portions of the conductive plates 108 , 109 to the gap 110 ( and , in use , to any tissue seated within the gap ). when assembled , the electrode cover 100 and platinum electrode foils 108 , 109 seat within the electrode shroud 101 as best shown in fig1 , 11 , 12 & amp ; 13 . fig1 in particular shown in cross - section where the electrode cover seats . electrode shroud 1 is formed from silicone . in order to provide reinforcement , pet mesh covers 111 , 112 are provided to fit to upper 113 and lower 114 extending portions of the shroud 101 . suture holes 115 , 116 are provided in the covers 111 , 112 and also in the elements 113 , 114 of the shroud 101 . note that the reinforcement can be provided by other means and is not limited to pet mesh . further , the electrode shroud need not be in silicone but could be of other bio - compatible material and may not require reinforcement . further , note that other means for affixing to the tissue may be provided other than suture holes or instead of suture holes . the electrode lead 102 is a multi - component arrangement which includes an outer insulating cover 120 , a tine collar 121 including tines 122 for retaining the lead in position within a patient . it also includes a sutured collar 123 including suture holes 124 for suturing to patient tissue to also facilitate retaining the lead 102 in position . there is also bifurcation moulding 125 which enables the lead to split into two parts 126 , 127 which may contain separate conductors , and connectors 128 , 129 which may be arranged to contact to a simulation device . in the above embodiments , the electrode arrangement includes a pair of electrode elements which extend away from a base which joins them together at their proximal ends . in a further embodiment , a single electrode element which is not joined at any base is provided . this single electrode element may be used to provide stimulation to contractile tissue on its own , or may be used together with one or more similar electrode elements to provide stimulation . in the above described embodiments , each electrode element is provided with a single electrode . the single electrode is an elongate electrode extending substantially the majority of the length of the electrode element . one advantage of having thin electrodes bounded by insulating material on either side is that the arrangement operates to confine the electric field produced by the electrode to the tissue immediately adjacent the electrode . this reduces or prevents stimulation of tissue that it is not desirable to stimulate e . g . tissue external to a contractile tissue sphincter being controlled . in operation , the electrodes 108 , 109 and extending elements 103 , 104 are positioned either side of the smooth muscle implant to enable signals to be transmitted to the implant for operation . electrode arrangement 3 a allows application of an electric field between the opposing electrode elements to stimulate the tissue between them . the electric field in one embodiment is confined so that stimulation is to a band of tissue between the electrodes . in one embodiment , innervation runs within the implant 2 perpendicular to the band of tissue being stimulated . the elements in electrode 3 a extend over the tissue in a manner analogous to that of a clothes peg . the elements in electrode 3 a extend over the tissue in a manner analogous to that of a clothes peg . other electrode patterns then a single line electrode on the surfaces of the elements may be utilised . as discussed above , in an embodiment , the stimulater implant is preferably sealed and encased in a biologically inert material such as a biocompatible silicone material . metallic electrodes and leads may be of plantinum - iridum alloy . the connecting wires are , in one embodiment , insulated with a silicon coating . the implant may be placed between the abdominal muscle and the skin . in the above embodiment , the stimulator is a totally implantable device . in an alternative embodiment , the stimulator may not be implantable . the stimulator in this embodiment may comprise a stimulator device having similar componentry to that discussed above in relation to the embodiment of fig3 , 4 and 5 , but being ranged to be placed externally of the patient . in one embodiment , signals are coupled to electrodes placed within the patient in order to stimulate the contractile tissue . coupling may be by way of inductively coupling the signals across the patient &# 39 ; s skin to an internally positioned electrode arrangement . in another embodiment , part of the stimulator componentry may be placed outside the patient and part inside the patient . in the above embodiments a single stimulation signal generator is used to provide the electrical signal . other embodiments may use two or more signal generators . other embodiments may use two or more stimulators , which may be placed in different locations . it will be appreciated by persons skilled in the art that numerous variations and / or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described . the present embodiments are , therefore , to be considered in all respects as illustrative and not restrictive . in the claims which follow and in the preceding description of the invention , except where the context requires otherwise due to express language or necessary implication , the word “ comprise ” or variations such as “ comprises ” or “ comprising ” is used in an inclusive sense , i . e . to specify the presence of the stated features but not to
the present invention relates to a method and apparatus for treating fecal incontinence . a smooth muscle sphincter is implanted about the distal part of the large intestine in the region of internal anal sphincter or the anal canal , the rectum or the sigmoid colon . the smooth muscle sphincter is electrically stimulated by a stimulator device , in order to contract the smooth muscle sphincter and maintain continence . stimulation is ceased or varied in order to allow the smooth muscle sphincter to relax and the patient to defecate .