Background of the Invention This invention relates to apparatus and a method for applying electrical energy to living tissue, and more particularly, to apparatus and a method for stimulating penile erectile tissue and a method of making such apparatus♦

As is well known, the erectile tissue of the penis is composed of hollow sinuses, the walls of which contain involuntary muscle tissue. Blood reaches the sinuses through arterioles and capillaries, and the outlets from the sinuses are also controlled by involuntary muscle. In erection, impluses from the pelvic nerve cause dilation of the arterioles and constriction of the involuntary muscle controlling the outlets from the sinuses. The combined effect of these actions is to dilate the vascular spaces and to create high pressure within them, causing hardening and erection of the organ.

Normal erection is dependent upon a complex interaction of psychological, neurological and vascular factors. Failure of any of them can result in an inability to

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sustain erection, a condition commonly referred to as male impotence.

It has been suggested that, in the case of individuals whose impotence is a result of certain neurological deficits, the application of external electrical stimu¬ lus may ameliorate the impotence. Thus, for example, in United States Patent No. 3,403,684, issued October 1 1968, to Stiebel, et al., a device was suggested in which a pair of electrodes were placed in the area of the prostate gland of a user, and it was proposed that an electrical signal be applied to the electrodes to cause electrical stimulation of the surrounding tissues.

It has now been demonstrated in laboratory animals that stimulation can best be accomplished by applying an electrical stimulus as directly as possible to certain highly sensitive and identifiable areas of the prostate gland. It is believed that if the signal is applied to these areas, the precise locations of which will vary from individual to individual, the nature of the signal is less critical than was formerly thought, and the de¬ sired results can be consistently and reliably obtained.

It is, therefore, a general object of this invention to provide apparatus and a method for stimulating erectile tissue, and more particularly apparatus and a method which are useful to promote penile erection by elec¬ trical stimulation.

Another object of this invention is to provide a method of making apparatus for stimulating penile erection, and it is still another object of the invention to provide a genital stimulator which is compact, self- contained, and capable of being accurately placed and positioned for use.

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Another object of this invention is to provide a geni¬ tal stimulator which is maintained in position for use by the anatomical structures, particularly the muscula¬ ture, which surround it when it is positioned for use.

Other objects will appear hereinafter.

The foregoing and other objects are realized, in a presently preferred form of the apparatus, by a sti u- lator which comprises a body member, the shape of which is determined by an impression molded in situ, and which is adapted for insertion into the rectum of a user. Molding in the above manner ensures that the body member is so configured as to closely conform to the unique configuration of the rectum of each user. Within the body member there is placed a highly minia¬ turized electrical signal generator, and electrodes are disposed at carefully selected localities on the outer surface of the body member. In accordance with the present invention, at least one electrode is juxtaposed as closely as possible to a selected spot on the pros¬ tate of the user which has been determined to be sensi¬ tive to electrical stimulation. Close conformity of the body member to the configuration of the rectum of the user, as well as a unique homeostatic effect de¬ scribed below, maintains the electrode in close proxim¬ ity to the sensitive spot, and assures application of electrical impulses to that spot to stimulate erection. Electrical signals are generated by signal generating circuitry disposed within a cavity in the body member, and the body member, signal generating circuitry and its associated power supply are self-contained. Actua¬ tion of the apparatus may be by means of a manually operated or magnetically activated switch associated with the body member, or by remote telemetric means.

In its method aspect, the present invention involves palpation of the prostate gland of-a potential user and application to the prostate, at selected spots, of an electrical impulse. The result of the application of the impulse at the selected spot can be sensed or observed, and determines for the clinician the efficacy of application of electrical stimulus to that spot. When the sensitive spot or spots of the prostate have been identified, an impression is taken of the rectum of the user in at least the region extending from the anus to a location proximate to the prostate gland, and from that impression, a body member closely conforming to the shape of the rectum can be made. Electrodes are positioned on the body member at locations correspond- ing to the previously identified sensitive spot or spots, and at other locations which provide suitable electrical contact with the tissues of the user.

The method of making the apparatus involves the taking of an impression of the rectum of the potential user by inserting into the rectum a sheath; injecting a molding composition into the sheath; permitting the molding composition to become somewhat hard; withdrawing the sheath slightly and permitting the composition to further harden; and then removing the sheath and the impression when the composition has fully hardened. The hardened composition thus forms an impression closely conforming to the configuration of the rectum, from which the body member of the apparatus may be molded. Electrodes can then be applied to the body member in positions corresponding to the sensitive spots on the prostate as earlier determined by palpa¬ tion and stimulation, and electrical circuitry may be placed within the body member to produce the above- described apparatus.

There are seen in the drawings forms of the invention which are presently preferred (and which represent the best mode contemplated for carrying the invention into effect), but it should be understood that the invention is not limited to the precise arrangements and instru¬ mentalities shown.

Description of Drawings

Figure 1 is a cross-sectional view, showing apparatus in accordance with the invention operatively disposed in the rectum of a user.

Figure 2 is a partial cross-sectional view, depicting aspects of the method by which apparatus in accordance with the present invention may be fitted to a user.

Figure 3 is another view depicting aspects of a method of making apparatus in accordance with the invention.

Figure 4 is a cross-sectional view of a female mold used in a method of making apparatus in accordance with the invention.

Figure 5 is a cross-sectional view, depicting another step in the method of making apparatus in accordance with the invention.

Figure 6 is a view, partly broken away, showing certain structural details of apparatus in accordance with the invention.

Figure 7 is a pictorial view of one form of apparatus in accordance with the invention.

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Figures 8, 9 and 10 are schematic diagrams illustrating exemplary electronic circuit means for use in the present invention.

Figure 11 illustrates apparatus which may conveniently be used for palpation and stimulation in practicing the present invention.

Detailed Description

Referring now to the drawings in detail, wherein like reference numerals indicate like elements, there is seen in Figures 1, 6 and 7, stimulator apparatus desig¬ nated generally by the reference numeral 10.

The apparatus 10 comprises a body member 12 _r adapted, as is best seen in Figure 1, for insertion into the rectum 14 of a user. The shape of the body member 12 is unique to each user, and is arrived at by molding in situ, in a manner described in detail below.

Disposed on the outer surface of the body member 12 are electrodes which are so positioned that when the body member 12 is properly disposed within the rectum 14 they intimately contact the mucosa of the rectum and adjacent structures. The electrodes comprise, in the illustrated embodiment, three ground electrodes, 16, 18 and 20, and what may be referred to conveniently as an active electrode 22. As is best seen in Figure 1, the electrodes 16, 18 and 20 confront the anal sphincter 24 of the user. The active electrode 22 intimately con¬ tacts the rectal wall, in juxtaposition to and in close contact with a critical region of the prostate gland 26.

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Referring to Figure 6, it will be seen that the body member 12 has an internal cavity 28, in which there is housed electrical and electronic components and cir¬ cuitry designated generally by the reference numeral 30. In general, the electrical and electronic compo¬ nents include a highly miniaturized and self-contained signal generator with associated control circuitry, and a power supply 32, all associated with a compact printed circuit board 34.

Referring now to Figures 6 and 7, the electrical and electronic components 28 may include an off-on switch 36, to activate the apparatus 10. In one form of the apparatus 10, in which the switch 36 is manually opera- ble, the switch 36 is disposed in an end wall 38 of the body member 12, and is accessible for manipulation when the apparatus 10 is operatively disposed. As an alter¬ native, the apparatus 10 may be activated by means of a radio frequency or other remote signal. Figure 8 illustrates an alternative switching and latching circuit, which serves (as does the manual switch 36) to activate the apparatus 10, placing the circuitry in an "on" condition and "latching" the circuitry 30 in that condition as long as desired. Referring again to Figures 6 and 7, the switch 36 may be encased within a flexible, liquid impervious end seal 38, sufficiently thin to permit ready manipulation of the switch 36 by applying external pressure to the end seal 38.

Referring now to Figures 2 through 5, a presently preferred technique or method by which the body member 12 may be molded is illustrated. Referring first to Figure 2, a finger 40 of a clinician or technician is placed in a flexible chemically inert sheath 42. The sheath 42 for this purpose may be an ordinary condom. The finger 40, encased in the sheath 42 is inserted

intra-anally to a depth of perhaps 10 cm., to a point at which, the prostate 26 may be palpated. Molding composition 44, contained in a syringe 46 whose tip 48 projects into the sheath 42, may now be injected into the sheath 42, thus filling the sheath and causing the sheath 42 to expand within the rectum 14. The molding composition 44 injected into the sheath 42, it has been found, can be of the kind known as Alginate or its equivalent, commonly used to make dental impressions- Such a material is prepared from a powder and water mixture, and, depending upon temperature, becomes firm but not rigid in about three to five minutes. The molding composition 44, once inserted into the sheath 42, is allowed to become semi-rigid, and the sheath 42 is then drawn rearwardly through the anus to a small extent so that the anal sphincter 24 tends to compress the rigidifying mass. It has been found that, at this stage of the procedure, the application of topical electrical stimulation to the anal area {on the order of about 3v. ) causes contraction of the musculature of the anal area so as to create an accurate and detailed outline of the configuration of the rectum 14. The sheath 42 is next left in position and the molding composition 44 is permitted to harden to form a plug¬ like mass 50 which closely conforms to the configura- tion of the subject's rectum and anus. ^"

^' Referring now to Figure 4, the mass 50 may be used, in a conventional manner, to make a female mold 52, and from the female mold 52 there may be made any number of duplicates of the mass 50. The duplicates may be made from plaster, dental stone, epoxy or vinyl molding compounds of numerous kinds as well as methyl methacry- late (acrylic). The mass 50 may be inserted into the rectum 14 and used to determine the position of the electrodes in a manner to be described below.

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Referring to Figure 5, the female mold 52 may be used to mold the final form of the body member 12. In the molding of the body member 12, the cavity 54 of the female mold 52 is partly fille by a core 56 suspended within the cavity 54. Material suitable for the body member 12 includes castable plastic polymeric materi¬ als, such as methylmethacrylate. This material, like other suitable materials, is chemically inert and usable in the body.

The material of the female mold 52, it should be under¬ stood, is of rubber-like composition, which can be deformed to permit removal of the molded article from the cavity 54. As an alternative, the female mold 52 may be a split mold, halves of which can be separated to free a sharply undercut molded article. Removal of the core 56 from the molded article yields a body of the kind shown in Figure 6, which includes a cavity 26 whose shape conforms to the core 56.

The electrodes 16, 18, 20 and 22 may now be applied to the body member 12. The electrode 22 is so positioned on the body member 12 that when the body member 12 is properly placed within the rectum, the electrode 22 is juxtaposed to a previously-determined sensitive spot 58 of the prostate 26, seen in Figure 1. The electrodes 16, 18 and 20 are so positioned as to be juxtaposed to the ring defined by the anal sphincter 24, and are grasped by the anus. The body member 12 may be pro- vided, when molded, with projections 60 (one of which is seen in Figure 6) at locations corresponding to the locations of the electrodes 16, 18, 20 and 22. This may be accomplished by appropriately adding material to the mass 50 or removing it from the female mold 52. The electrodes themselves may advantageously be "dished" to conform to the projections 60, and to

present a convex outer surface which enhances electri¬ cal contact with surrounding tissues. The electrodes 16, 18, 20 and 22 may be of platinum or other suitable conductive, inert, non-polarizing material affixed to the body member 12 by suitable adhesives.

An important aspect of the invention is the manner in which the body member 12 with its associated electrodes is held in position by the configuration of the rectum. The above-described molding technique, which yields a body member 12 closely conforming to the shape of the rectum, causes the body member 12, when positioned within the rectum, to be constrained against either rotation or movement axially with respect to the anal orifice. Thus, the body member 12, and consequently the electrodes 16, 18, 20 and 22 are maintained by the anal cleft and the shape of the rectum 14 in a desired orientation with respect to the prostate gland 26. The above-described steps of allowing the molding composi- tion 44 to become semi-rigid and then drawing the sheath 42 through the anus to a small extent assure that the impression defined by the mass 54 encompasses regions within the rectum 14 and also regions external of the anus. Contact between the body member 12 and the irregularly configured surrounding structures tends to maintain the body member 12 in precisely the desired position. The body member 12 may also be made with a roughend surface, to minimize any tendency of the appa¬ ratus 10 to shift with respect to the surrounding structures.

Identification of the spot or spots to be stimulated by the apparatus 10 is accomplished by applying to the prostate gland 26 electrical energy which simulates the erection-stimulating signal ultimately to be produced by the apparatus 10. Such applications, when made at

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sensitive spots, cause palpable or visible physical reactions which are signs of incipient erection. The presently, preferred technique for locating sensitive spots is the use of glove-mounted electrodes of the kinds described in co-pending application, Serial No. 452,319 filed December 22, 1982, for "MEANS FOR TRANS¬ FERRING ELECTRICAL ENERGY TO AND FROM LIVING TISSUE" (assigned to the assignee of the present application), and illustrated in Figure 11 herein. It has been found in laboratory animals that the application of electri¬ cal stimuli to critical spots of the prostate yields the desired result, while other regions show relative insensitivity to the application of the stimulus. As has been explained, advantages of the present apparatus and method flow from the ability of the apparatus 10 to apply energy directly to only those specific regions which have been ascertained to provide the desired result. When desirable spots have been identified and noted, the desired locations of electrodes such as the electrode 22 on the body member 12 may be ascertained by measurement, so that when the apparatus 10 is posi¬ tioned for use, the active electrodes are proximal the efficacious spots on the user's prostate gland. As indicated above, the unique shape of the body member 12, cooperating with key anatomical landmarks, serves to maintain the apparatus 10 in precisely the desired orientation with respect to the rectum and prostate gland, so that the electrodes are maintained in close contact with the anatomical structures adjacent to which they are placed. In humans, the anatomical landmarks which maintain the apparatus 10 in position include the anal cleft, the configuration and angular orientation of the anal sphincter, and the position and configuration of the prostate gland itself.

A unique characteristic of the apparatus 10, which has been observed in laboratory animals, is its tendency to induce in the anatomical structures surrounding it forces which tend to restore the appratus 10 and its associated electrodes to their desired positions. In other words, it has been found that the apparatus 10 creates what may be characterized as a self-restorative or homeostatic force, by electromechanical feedback resulting from displacement of the appratus 10. This effect, it is theorized, is due to the fact that tran¬ sient lateral displacement of an electrode such as the electrode 22 results in the application of electrical energy to the tissues contacted by the displaced elec¬ trode. This, it has been found, results in contraction of localized myofibers in those specific areas, and such contractions, due to the shape of the body member 12 and the surrounding anatomy tend to urge the appa¬ ratus 10 and electrode 22 to their original and desired positions. This homeostatic mechanism aids the above- described interaction between the shape of the body member 12 and surrounding anatomical landmarks to maintain the apparatus 10 and the electrodes in their desired positions.

Figure 9 illustrates a presently preferred electronic circuit by which stimulating signals can be produced, although other specific circuitry may perform the same function. The illustrated circuitry includes an asta- ble multivibrator, designated generally by the refer- ence numeral 62; a monostable multivibrator, designated generally by the reference numeral 64; NAND gating 66, the purpose of which will be described below; two inverters 68 and 70; and an emitter-follower 72 provid¬ ing a "high" voltage (about 20 volts) output.

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The power supply 32 in the presently preferred form of the invention is provided by lithium batteries (seen in Figure 6), maintained in series relationship by a shrink-fitted sleeve as is known in the art. In one form of the invention, the power supply 32 consists of two 3.0 volt batteries, producing six volts, and eight 3.0 volt batteries, providing 24 volts.

The astable multivibrator 62 and monostable ultivi- brator 64, which comprise the first and second stages of the circuitry 30, provide pulses of approximately six volts, and of a desired pulse-width and frequency. Thus,, in the illustrated circuitry 30, the output of the astable multivibrator 62 is a series of square pulses at an amplitude of six volts and a frequency of about 30 to 33 Hz, and the monostable multivibrator 64 serves to shape the pulses to a presently preferred width of 500 microseconds.

The principal components of the illustrated astable and monostable multivibrators 62, 64 are commercially available highly miniaturized integrated circuits. Thus, with reference to the astable multivibrator 62, each of the integrated circuits (labeled "IC-1") are of a type sold by Amperex Electronics Corporation, a sub¬ sidiary of North American Phillips Corp., as so-called "leadless inverted devices" ("LIDS"). They are elec¬ tronically equivalent, however, to standard sized inte¬ grated circuits. The integrated circuit 74, for exam- pie, in Figure 9, and the other integrated circuits labeled "IC-1" are "LIDS" equivalent to CMOS No. 4011 integrated circuits available from numerous manufac¬ turers, including, among others, RCA, Texas Instruments Corp., National Semiconductor, and Solid State Scien- tific. All of the other components in the preferred form of the circuitry 30 are commercially available

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items. By way of illustration, the diode 76 in one operative form of the circuitry is an Amperex Elec¬ tronic Corporation Part No. LDD-5. The NPN transistor 78 used in the inverter circuit 68 is an Amperex LDA- 404 {"LIDS" equivalent to 2N 3904). The PNP transistor 80 in the inverter 70 is an Amperex LDA-452, equivalent to a 2N 3906. The NPN transistor 82 is also an Amperex LDA-404.

The circuitry 30 illustrated in Figure 9, as presently contemplated, may use one of two modes of control. In the first mode, perhaps best seen in Figure 9, manual operation of the switch S., (the above-mentioned switch 36, seen in Figures 6 and 7), applies to the astable multivibrator 62, monostable multivibrator 64, and other aspects of the circuitry 30, the 6 volt supply. An output pulse will be repetitively supplied during - the time in which the circuitry 30 is so powered. In other words, stimulation is enabled upon closing of the switch 36 to power the circuit, and stimulation is inhibited when the switch 36 is open.

Referring now to Figure 8, there is seen an alternative arrangement for enabling stimulation, using an external reed switch 84 to control pulse output, and hence stimulation. The reed switch 84 may advantageously be operated by an external magnet or other remotely opera¬ ble means, under the control of the user.

The reed switch 84 controls a flip-flop, designated generally by the reference numeral 86, which performs a latching function with respect to the power supply of the circuitry 30. The flip-flop 86 in its presently preferred form, is based upon an LIDS equivalent 4013 integrated circuit (LFF 4013), supplying, through the output resistor 88 a PNP transistor 90 (LDA 452-, LIDS

equivalent to 2N3906). Because it is of the PNP type, the transistor 90 is "off" when it sees high , and when the transistor 90 is off no voltage will be seen at the six volt input of the circuitry 30. It will be 5 appreciated, however, that changing the state of the flip-flop 86 will turn on the six volt supply to the circuitry 30, thus enabling stimulation.

The apparatus illustrated in Figure 8 thus provides both a latching function (enabling continuous stimula¬ tion) -and a controlled six volt power supply for the circuitry 30. The circuitry illustrated in Figure 8 enables the stimulator apparatus 10 to be inserted into or removed from the rectum 14 with assurance that the apparatus 10 is inhibited, thus eliminating undesirable effects such as untimely or unwanted neural stimulation affecting muscle groups other than those involved in penile erection.

Figure 10 illustrates diagrammatically the functional interrelationship between the reed switch 84, the flip-flop 86, the signal generating and control cir¬ cuitry 62, 66, 68 and 72, and the power supply (repre¬ sented in Figure 10 by six volt and high voltage sources corresponding to the power supply 32). As can be seen in Figure 10, closing of the reed switch 84 (by magnetic or remote means) configures the flip-flop 86 to provide to the other circuitry a controlled six volt supply. The other circuitry, in turn provides the stimulating signal and delivers it to the active elec¬ trode 22.

The above-described circuitry 30 is designed to drive ^* an output load of approximately 330 ohms (the assumed load resistance based on observations in laboratory animals). When the output pulse is inhibited, the

output is zero volts. When the output is enabled, the actual output level is a function of the voltage of the high voltage supply (V. ). In one operative embodi¬ ment, the high voltage supply provides twenty-four volts, and the output is within 0.5 volts of this voltage and substantially constant for 500 microseconds when driving a 330 ohm load.

Those skilled in the art will appreciate that the high and low voltages, as well as the parameters (pulse width, frequency and wave form) of the output pulse may be varied by conventional circuit elements, perhaps controlled by telemetry. Utilizing appropriate feed¬ back mechanisms, the circuit may be made self-regulating and self-optimizing.

Figure 11 illustrates, somewhat schematically, a surgi¬ cal glove 92, to which there are affixed electrodes 94. The electrodes 94 may be electrically connected to a source 96 of electrical energy, such as a signal gener¬ ating circuit analogous to the above-described cir¬ cuitry 30. Palpation may thus be done using the glove 92, and stimulation may be accomplished by application of electrical energy through the electrodes 94.

The present invention may be embodied in other specific forms without departing from its spirit and essential attributes and, accordingly, reference should be made to the appended claims rather than the foregoing speci- fication as indicating the scope of the invention.