Chapter 10.2 Managing Functional Problems Following Dynamic Graciloplasty

Chapter 10.2

Managing Functional Problems Following Dynamic Graciloplasty

Cornelius G.M.I. Baeten and Mart J. Rongen

Dynamic graciloplasty is a technique for patients with severe fecal inconti- nence who cannot be treated with other methods. The technique is based upon a much older operation described by Pickrell (1). In this operation, a gracilis muscle is wrapped around the anus. The main artery, vein, and nerve of this muscle are preserved. This muscle can only contract by will and closes the anal canal, and active voluntary contraction is only possible for a few minutes. The gracilis contains a majority of type II fibers that are very fatigable. Type II fibers can be changed into type I fibers by electrical stim- ulation (2). Every muscle is composed of a certain proportion of type I and II fibers dictated by the nerve leading to this muscle. The electrical stimu- lation “tricks the nerve” and the muscle changes towards the properties of the stimulated nerve. The same will happen when the nerves of two muscles are transected and are crosswise anastomosed. The muscles will both change to the characteristics of each other.

The problem that patients with fecal incontinence treated with a con- ventional graciloplasty have to overcome are twofold:

1. They have to concentrate on contracting the muscle. Psychologically, this is only possible for a very short time.

2. The muscle fatigues and the patients have to find a toilet in a few minutes, otherwise the muscle will relax and stool is lost.

Combining Pickrell’s technique (3) with the idea that a muscle can be changed by low-frequency electrical stimulation made it possible to change the gracilis muscle into a nonfatigable muscle (4) that contracts, because it is forced to do so on demand of the stimulator. Cerebral attention is no longer necessary. The combination of conventional graciloplasty with elec- trical stimulation is called dynamic graciloplasty. The only cerebral activity is to register a call to stool and to take the remote control to switch “off”

the stimulator. No stimuli will go to the muscle, the muscle will then relax, the anus opens, and the patient can defecate. After defecation, the stimu- lator can be switched “on” again with the same remote control so that the anus will close again.

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In the literature, the successful outcome of dynamic graciloplasty varies from 56% to 80% (5–8). This success rate is acceptable because this tech- nique is used as a last resort for patients who have already been treated unsuccessfully in various other ways. Dynamic graciloplasty is used in patients with severe fecal incontinence in whom diets, constipating drugs, biofeedback therapy, anal repair, and other operations have failed. The success can be obtained at the cost of many complications, most of which are treatable (9,10). Some of the problems seen in dynamic graciloplasty can be considered functional and form the subject of this chapter. The most important functional problems are: (A) non-contractility of the gracilis muscle, (B) persisting incontinence, and (C) constipation.

Non Contractility of the Gracilis

When after dynamic graciloplasty the muscle does not contract sufficiently, or not at all, it is important to find the cause and to ascertain whether it is a primary muscle problem or a stimulation problem. The difference can be found in a very simple way. The gracilis still has its own intact nerve and the patient is able to contract the muscle voluntarily.

When a voluntary contraction of the gracilis wrap is possible, the problem is not a muscle problem, but probably represents a stimulation failure. In a voluntary contraction, all the motor units in the gracilis are recruited and the muscle will give its maximal force. A contraction based upon electrical stimulation can, at its best, generate the same force as in a voluntary con- traction, but it is more likely that the generated force will be suboptimal.

The force is dependent on the number of motor units that can be activated by electrical stimulation. Every motor unit consists of a nerve fiber con- nected to one or more muscle fibers. The number of nerve fibers located in the electrical field between the electrodes determines the number of muscle fibers that will contract. This force is dependent on the localization of the electrode next to the nerve, on the amplitude, on the pulse width and fre- quency of the stimulation (Figure 10.2.1).

With higher amplitude, more motor units will be activated up to a maximum. When all fibers in the nerve are stimulated, a further increase in amplitude will not generate more force. Initially, poor contraction is most likely based upon a bad positioning of the electrode; the solution is rein- sertion of the lead. A secondary poor contraction can be based upon dis- location of the electrode or on two physiological phenomena.

1. Fibrosis will be formed around the electrode and higher amplitude is necessary to generate the same contraction force (11).

2. The muscle fibers will be changed from type II to type I. Type 1 fibers are less forceful.

Another reason for loss of contraction could be a possible breakage of the electrode. In our experience with 300 patients and 600 electrodes, this has never happened; the solution in such a case is electrode replacement.

On one occasion, our unit experienced damage to the isolation sheath and a leakage of current leading to weak contraction of the muscle. The solu- tion here was replacement of the electrode. Loss of contraction also can occur when the electrode is distracted from the muscle. Dislocation means that the electrode generates an electrical field, but the nerve to the gracilis is no longer in the vicinity of this field. We have observed this once in a patient who played with the stimulator located in a subcutaneous pocket, where she turned the stimulator around and the electrodes twisted around and were torn out of the gracilis. The therapy there was reinsertion of the electrode.

Weak contraction can be seen when the amplitude is too low, meaning that the amplitude is close to the threshold. The threshold is the lowest amplitude with which a reaction of the muscle can be seen; the therapy was to reprogram the stimulator to a higher amplitude. Non-contraction of course is seen when the battery is empty. In that case, the programming of the stimulator is no longer possible. For the most part, the nearing end of the battery can be detected a few months earlier during programming.

The solution here is simple: the implantable pulse generator (IPG) has to be replaced. The longevity of the stimulator is dependant upon the

Figure 10.2.1. Electrically stimulated graciloplasty design. The circles represent motor units (shaded circles are conversion to Type I fibers for

continuous contraction).

programmed amplitude and frequency, and in our experience, this lasts for a median of about eight years (8). The programming of the stimulator itself is not very difficult. Changes can be made in amplitude, frequency, pulse width, the polarity of the electrodes, and in the IPG. The impedance can be measured, providing an indication whether or not the electrodes are intact or dislocated. Almost all stimulation problems are potentially solvable.

When the problem of poor or non-contractility is not a stimulation problem, the cause is most likely a malfunction of the muscle itself. The test to determine this has already been discussed. When no voluntary contrac- tion is possible, something is primarily wrong with the muscle. The gracilis muscle is the most superficial adductor in the upper leg and is innervated by a branch of the obturator nerve. This nerve is always accompanied by the branches of the obturator artery and vein. These three structures reach the gracilis muscle invariably eight centimeters from the origin of the gra- cilis. In freeing the gracilis muscle for the transposition around the anus, the nerve, artery, and/or vein can be damaged. These structures can also be damaged by traction in the transposition position. Damage of the nerve leads to atrophy, occlusion of the artery and necrosis, whereas damage to the vein leads to significant muscle congestion. This damage can lead to the disappearance of the entire muscle or to its deterioration into a fibrotic string around the anus so that the contractile function is lost. This problem has never been seen in our experience of over 300 dynamic graciloplasties.

The gracilis also has peripheral arteries and veins. The number of periph- eral arteries varies between patients, and in one patient even between the left and the right sides.

These peripheral structures have to be divided in order to make an adequate functioning gracilis wrap. In most cases, this division creates no problem for the survival of the muscle because the vessels of the gracilis form one vascular network that can sufficiently vascularize the whole muscle from the main proximal artery and vein (12). Nevertheless, in some muscles, the division leads to hypoperfusion of the distal part and to its distal fibrosis. When the distal part cannot contract, this leads to malfunc- tion of the dynamic graciloplasty. This problem is seen in a small percent- age of patients. The solution is a new graciloplasty from the other side or the application of another technique such as the artificial bowel sphincter (ABS) (13) (see Chapter 10.3).

Non-contractility of the gracilis seems to be present when the wrap is too loose.The muscle is not able to constrict the anal canal sufficiently.The same phenomenon occurs when the attachment of the distal tendon of the muscle to the periosteum of the pubic bone loosens. In these cases, re-attachment or shortening of the tendon can be a solution. During graciloplasty, it is always difficult to judge how tight the wrap must be, and as a general rule, we place one finger between the anus and the gracilis wrap and then suture the distal tendon tightly to fit against the pubic bone.

Non-contractility is also seen when the patient is under general anesthe- sia and muscle relaxants are used. This, of course, will disappear when the patient is awakened. General neurological diseases seldom afflict the gra- cilis muscle, and even in cases of paresis of the whole leg, the gracilis stays functional.

Persisting Incontinence

One of the most frustrating findings after graciloplasty is when the patient is not able to control stool despite a well-contracting muscle. One has to realize that continence is much more than only the function of the sphinc- ters. When a patient with fecal incontinence is analyzed and a deficient sphincter is found, it is logical that this is an indication to restore that func- tion with an anal repair, a dynamic graciloplasty or an ABS. Other reasons for incontinence can be under-detected at that stage. When we assess patients with incontinence after a successful restoration of sphincter func- tion, problems of hyposensibility, deficient rectal capacity, or rectal compli- ance with loose consistency of the stool become more prominent. Therapies to improve rectal sensibility are not always successful, and the only thing that can be done is to try physiotherapy with rectal balloons. A balloon can be placed into the rectum and inflated with several different volumes of air.

The patient can try to concentrate on feeling low filling volumes. The stool consistency can be influenced by diets or constipating drugs, and the capac- ity of the rectum can be enlarged by gradual rectal filling with balloon dis- tension or by operations to augment the rectum. A good technique is to bring down a vascular-intact bowel loop and to suture this onto the opened frontal side of the rectum in the same way as urologists create a bladder augmentation (e.g., cecocystoplasty) (14). However, even with these extra therapies in quite a number of cases, patients often stay incontinent and operations to restore the sphincter function are blamed for this poor outcome. However, they often are successful in improving sphincter func- tion, although they cannot make up for the other deficient factors. Combi- nations of sphincter restoration and conservative therapy often ultimately result in success.

Constipation

One of the most frequent functional problems after dynamic graciloplasty is constipation. The first thought, of course, is that the wrap is too tight, forming an obstruction. This indeed can happen once in a while, but is actu- ally quite rare. We have seen such a stenosis in only five cases in 300 patients (1.6%). Therapy for this condition includes detachment of the gracilis tendon, resulting in a good outcome in two of these five patients so that the cut tendon allowed the gracilis to retract over a small distance. The gracilis

probably was connected to the surrounding tissue in such a way that a complete retraction did not occur. Two patients stayed continent after this procedure.

In most cases, the constipation is seen in patients who have a normal accessible anus and anal manometry shows normal values. We found con- stipation without stenosis in 16% of our cases. It is very frustrating for the patients when incontinence for feces is replaced by severe constipation.

Here, transit studies in these patients often give an indication for slow- transit constipation without outlet obstruction. One can speculate how this is possible, where many patients have a history of constipation first devel- oping in their youth. Severe constipation may lead to expulsion difficulties and destruction of the anal sphincters. These patients then become incon- tinent despite their firm stool and hidden constipation. When patients are seen in the phase of incontinence, therapies like dynamic graciloplasty are provided in specialist units. This restores the sphincter function; however, the original problem resurfaces. There is no absolute proof of this, but it provides an acceptable explanation of this problem.

The treatment for this constipation is initially dietary therapy and laxa- tive drugs. In most cases, this is sufficient, but some patients require enemas.

Here, water enemas can be used in small volumes with a syringe or in large volumes with the aid of a pump. This retrograde lavage (15) of the colon is almost always successful. The median time to clean the bowel is usually about 20 minutes. Two patients in our series had no success with this ret- rograde lavage and complained that only the distal part of the colon was effectively emptied. In these patients, we used a Malone appendicostomy for antegrade lavage (16). This resulted in one good and one poor outcome.

Of course, one can argue that patients who need to lavage the colon after dynamic graciloplasty probably have “pseudoincontinence” and do not need their graciloplasty in the first place. Nevertheless, these patients benefit from the tighter anus that makes it possible to instill the fluid into the colon without leakage. During the time between two separate lavages, these patients remained continent. Another form of antegrade lavage is described by the group headed by Professor Norman Williams (17). They divided the sigmoid colon and constructed an end-to-side anastomosis of the proximal part to the distal part. Here, the transected distal portion was then invaginated and anastomosed to the skin of the abdomen as a conti- nent stoma for antegrade tap-water irrigation. Although good results have been described with this procedure, the extra intervention is complex when compared with the Malone procedure.

Conclusions

Graciloplasty has been used in one form or another for fecal incontinence since 1946, although electrically stimulated graciloplasty designed to convert fatigable fibers into fatigue-resistant fibers has only been intro-

duced and studied in the last 15 years. In well-selected patients, there is a durable success in over 70% of cases (18). Disturbances of evacuation are a problem in up to one-fifth of cases, although this is usually a temporary problem. We still require parameters that are more likely to accurately predict successful outcome following this procedure. It may well be that dynamic graciloplasty might be successful in those patients where initial sacral neuromodulation has provided only limited response, and in this regard, dynamic graciloplasty has paved the way for improved understand- ing of the effects of electrical stimulation on the anal sphincter (19).

References

1. Pickrell KL, Broadbent TR, Masters FW, and Metzger JT. Construction of a rectal sphincter and restoration of continence by transplanting the gracilis muscle. Ann Surg. 1952;135(6):853–62.

2. Pette D. Fiber transformation and fiber replacement in chronically stimulated muscle. J Heart Lung Transplant. 1992;11:S299–S305.

3. Baeten C, Spaans F, and Fluks A. An implanted neuromuscular stimulator for fecal continence following previously implanted gracilis muscle. Report of a case. Dis Colon Rectum. 1988;31(2):134–7.

4. Konsten J, Baeten CG, Havenith MG, and Soeters PB. Morphology of dynamic graciloplasty compared with the anal sphincter. Dis Colon Rectum. 1993;36(6):

559–63.

5. Mander BJ, Wexner SD, Williams NS, Bartolo DC, Lubowski DZ, Oresland T, et al. Preliminary results of a multicentre trial of the electrically stimulated gracilis neoanal sphincter. Br J Surg. 1999;86(12):1543–8.

6. Seccia M, Menconi C, Balestri R, and Cavina E. Study protocols and functional results in 86 electrostimulated graciloplasties. Dis Colon Rectum. 1994;37(9):

897–904.

7. Mavrantonis C, Billotti VL, and Wexner SD. Stimulated graciloplasty for treatment of intractable fecal incontinence: critical influence of the method of stimulation. Dis Colon Rectum. 1999;42(4):497–504.

8. Rongen MJGMU, O; El Naggar K, Geerdes BP, Konsten J, and Baeten CGMI.

Long term results of dynamic graciloplasty for fecal incontinence. Dis Colon Rectum. In press 2003.

9. Matzel KE, Madoff RD, LaFontaine LJ, Baeten CG, Buie WD, Christiansen J, et al. Complications of dynamic graciloplasty: incidence, management, and impact on outcome. Dis Colon Rectum. 2001;44(10):1427–35.

10. Geerdes BP, Heineman E, Konsten J, Soeters PB, and Baeten CG. Dynamic graciloplasty. Complications and management. Dis Colon Rectum. 1996;39(8):

912–17.

11. Rongen MJGM, Adang EM, Gerritsen van der Hoop A, and Baeten CI.

One step versus two step procedure in dynamic graciloplasty. Submitted 1999.

12. Geerdes BP, Kurvers HA, Konsten J, Heineman E, and Baeten CG. Assessment of ischaemia of the distal part of the gracilis muscle during transposition for anal dynamic graciloplasty. Br J Surg. 1997;84(8):1127–9.

13. Wong WD, Congliosi SM, Spencer MP, et al. The safety and efficacy of the arti- ficial bowel sphincter for fecal incontinence: results from a multicenter cohort study. Dis Colon Rectum. 2002;45(9):1139–53.

14. Williams NS, Ogunbiyi OA, Scott SM, Fajobi O, and Lunniss PJ. Rectal aug- mentation and stimulated gracilis anal neosphincter: a new approach in the management of fecal urgency and incontinence. Dis Colon Rectum. 2001;44:

192–8.

15. Briel JW, Schouten WR, Vlot EA, Smits S, and van Kessel I. Clinical value of colonic irrigation in patients with continence disturbances. Dis Colon Rectum.

1997;40(7):802–5.

16. Rongen MJ, van der Hoop AG, and Baeten CG. Cecal access for antegrade colon enemas in medically refractory slow-transit constipation: a prospective study.

Dis Colon Rectum. 2001;44(11):1644–9.

17. Abercrombie JE and Williams NS. Total anorectal reconstruction. Br J Surg.

1995;82(4):438–42.

18. Rongen MJ, Uludag O, El Naggar K, Gerdes BP, Konsten J, and Baeten CG.

Long-term follow-up of dynamic graciloplasty for fecal incontinence. Dis Colon Rectum. 2003;46:716–21.

19. Baeten CG, Bailey HR, Bakka A, et al. Safety and efficacy of dynamic gracilo- plasty for fecal incontinence: report of a prospective, multicenter trial. Dynamic Graciloplasty Therapy Study Group. Dis Colon Rectum. 2000;43:743–51.

Editorial Commentary

Dynamic graciloplasty has become a widely accepted option for the treat- ment of severe fecal incontinence in patients otherwise refractory for treatment and potentially destined for a stoma. The technique was largely championed and developed by Dr. Cornelius Baeten and therefore it is appropriate that along with his coworkers he has provided the information.

He notes that the successful outcome of this operation varies from 56% to 80% and describes many of the reasons for failure of the operation to achieve its optimal goal, showing the significance of noncontractility in con- stipation which may occur following this operation. Although the dynamic graciloplasty is no longer available in the United States it is available throughout the rest of the world and many patients in the United States have already undergone this operation necessitating some familiarity with its complications and aftermath which directly affect outcome and case pre- sentation to the coloproctologist working in a tertiary referral center.

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