Application of Individualized Intensive Biofeedback Electrical Stimulation Therapy in the Recovery of Anal Function After Anal Reconstruction: A Case Report

Abstract

Introduction and Importance:

For patients with locally advanced low rectal cancer (LARC) unresponsive to neoadjuvant chemoradiotherapy, achieving functional sphincter preservation remains a major challenge due to tumor invasiveness and complex anal reconstruction requirements.

Case presentation:

A 67-year-old female with LARC underwent extended radical resection involving anal sphincter/puborectalis muscle excision and partial vaginal wall resection. Anal reconstruction was performed via a free left gracilis myocutaneous flap routed in a “γ-shaped” configuration. Postoperatively, an individualized intensive biofeedback electrical stimulation regimen was implemented. After 2 months of training, the patient’s anal function had significantly improved, as evidenced by the results of the anorectal manometry (pre-training vs. post-training resting pressure: 24.7 vs. 59.4 mmHg; contraction pressure: 35.1 vs. 434.0 mmHg). As a result, stoma reversal was successfully achieved, and the patient’s postoperative anal function is now good (Williams A, Wenxer score 8).

Clinical Discussion:

Gracilis muscle transplantation provides a viable option for sphincter reconstruction in LARC. Compared with conventional regimens, individualized intensive biofeedback electrical stimulation regimen can not only promote muscle fiber transformation but also significantly improve muscle contraction strength and endurance, addressing the limitations of traditional methods.

Conclusion:

This case highlights the efficacy of gracilis muscle transplantation for sphincter reconstruction and underscores the critical role of tailored biofeedback electrical stimulation in enhancing gracilis muscle contractility and endurance, and promoting anal function recovery. Our findings suggest that this multimodal approach offers a viable strategy for achieving functional sphincter preservation in low LARC, potentially improving long-term quality of life.

Introduction

In recent years, as multimodal therapy has become the mainstream treatment for low rectal cancer^[1], neoadjuvant chemoradiotherapy (nCRT) not only facilitates tumor downstaging^[2] in patients with locally advanced low rectal cancer (LARC) but also enhances sphincter preservation rates and prognosis^[3]. However, for patients who are unresponsive to nCRT, sphincter-preserving operation poses significant challenges^[4,5].

In this report, we present a patient with low LARC who underwent anal reconstruction surgery with gracilis muscle transplantation. Through individualized intensive biofeedback electrical stimulation training regimen, the patient has currently undergone colostomy and has good anal function. We discuss the significance of gracilis muscle transplantation for external anal sphincter reconstruction in achieving functional sphincter preservation for low LARC, as well as the importance of our center’s individualized intensive biofeedback electrical stimulation training program in postoperative anal function recovery. This case aims to provide new insights and experiences for functional sphincter preservation in low LARC. This case report is in line with the SCARE Criteria^[6].

Case presentation

A 67-year-old female was admitted to our hospital due to increased frequency of bowel movements and thinning of stool for over 6 months. Approximately 6 months prior, the patient sought medical attention at a local hospital for symptoms including increased frequency of bowel movements, thinning of stool, and paroxysmal abdominal pain. She was diagnosed with rectal adenocarcinoma (cT4aN1M0) and subsequently underwent nCRT at the local hospital from 25 May 2023, to 5 July 2023. From 25 July 2023, to 26 October 2023, she received five cycles of chemotherapy with mFOLFOX6. She was referred to our hospital for further surgical treatment. Digital rectal examination revealed a mass located 1 cm from the anal verge, which was firm, immobile, and had an irregular surface. Blood staining was observed on the glove upon withdrawal.

Blood tests revealed hypoalbuminemia (albumin 30.5 g/L), moderate anemia (hemoglobin 77 g/L, HTC 23.4%), and leukopenia (white blood cell (WBC) 1.3 × 10^9/L). CEA and CA199 were normal. Magnetic resonance imaging (MRI) confirmed the diagnosis of rectal cancer with extraserosal invasion, staged as mrT4N0M0, with positive mesorectal fascia (MRF) and extramural vascular invasion (EMVI) (Fig. 1A). Colonoscopy identified an ulceroproliferative lesion located 1 cm from the anal verge to the anal margin, and the lumen was severely narrowed, allowing only minimal passage of the colonoscope (Fig. 1B). Biopsy pathology confirmed the diagnosis of rectal adenocarcinoma, predominantly composed of signet-ring cell carcinoma.

HIGHLIGHTS

• Locally advanced low rectal cancer (LARC) unresponsive to neoadjuvant chemoradiotherapy poses significant challenges for sphincter preservation.

• Gracilis muscle transplantation with “γ-shaped” routing configuration successfully achieved anal sphincter reconstruction in LARC requiring pelvic exenteration.

• Individualized intensive biofeedback-electrical stimulation regimen demonstrated superior efficacy in promoting gracilis muscle contractility and endurance.

• Comprehensive manometric improvements (resting pressure: 24.7→59.4 mmHg; contraction pressure: 35.1→ 434.0 mmHg) enabled successful stoma reversal with excellent postoperative continence (Williams A, Wenxer score 8).

• High-frequency, phase-adapted training protocol addressed limitations of traditional biofeedback methods, establishing a new strategy for post-transplant functional recovery.

Figure 1.

Preoperative diagnosis and radical resection of rectal cancer. (A) Magnetic resonance imaging (MRI) scans confirmed the diagnosis of rectal cancer with extraserosal invasion, staged as mrT4N0M0, with positive mesorectal fascia (MRF) and extramural vascular invasion (EMVI); (B) Colonoscopy identified an ulceroproliferative lesion located 8 cm from the anal verge to the anal margin, and the intestinal cavity was too narrow to barely passes through; (C) Perineal view after extended radical resection and pelvic exenteration for rectal cancer; (D) Pull-through anorectal reconstruction; (E) Intraoperative frozen section biopsy confirmed negative vaginal posterior wall resection margins.

Upon admission, the patient was treated with albumin infusion, blood transfusion, erythropoiesis-stimulating agents, leukopoiesis-stimulating agents, and intravenous nutritional support. Follow-up blood tests revealed significant improvement in albumin levels (albumin 37 g/L) and normalization of blood counts (hemoglobin 116 g/L, HCT 36.7%; WBC 5.0 × 10^9/L). After sufficient preoperative preparations, the patient underwent a radical operation. Intraoperative exploration revealed a firm, immobile, and irregularly surfaced mass located 1 cm from the anal verge in the lithotomy position, with tumor invasion into the posterior vaginal wall. The operations included extended radical resection of the rectal cancer (resection of the anal sphincter and puborectalis muscle, partial resection of the posterior vaginal wall, and pull-through anastomosis of the rectum and anal canal), posterior pelvic exenteration, gracilis muscle transplantation, abdominoperineal anoplasty, and terminal ileostomy (Fig. 1C and D). The posterior vaginal wall was sutured following confirmation of negative margins by intraoperative frozen section biopsy (Fig. 1E). The external anal sphincter was reconstructed using a free left gracilis myocutaneous flap. The flap was routed in a “γ-shaped” configuration to circumferentially encase the intestinal canal, with its distal end anchored to the periosteum of the right ischium (Fig. 2A and B).

Figure 2.

Gracilis muscle transplantation for anal reconstruction and secondary operation. (A) Gracilis myocutaneous flap transplantation and “γ-shaped” design; (B) Wound condition after anal reconstruction with gracilis muscle transplantation; (C) The final pathological diagnosis was signet ring cell carcinoma; (D) Pull-through intestinal condition 2 weeks after operation; (E) The perineal wound healing of the patient 3 months after operation.

Postoperative pathology revealed rectal signet-ring cell carcinoma, ulcerative type, measuring 4.5 × 3 × 1.1 cm, invading the anal canal wall and posterior vaginal wall, with no evidence of vascular or neural invasion, pT4N0M0 (Fig. 2C). The patient achieved favorable postoperative clinical outcome, with satisfactory healing of the perianal incision. The redundant pull-through intestinal segment was excised 2 weeks postoperatively (Fig. 2D), and the patient was discharged 3 weeks after surgery. The perineal wound healed well 4 months after operation (Fig. 2E).

The patient started individualized intensive biofeedback electrical stimulation training program 3 months after surgery. The training regimen consisted of a 20-minute Kegel template session, followed by 20 minutes of electrical stimulation therapy, and another 20-minute Kegel template session, constituting one treatment cycle. The patient completed two cycles per day, 5 days a week. The biofeedback training was divided into three phases on the basis of the average muscle fiber activity detected during the initial assessment: pre-intermediate level (10-15 μV), intermediate-advanced level(15-20 μV), and advanced level(20-30 μV). During the intermediate-advanced level, a gradual increase in both slow and fast muscle training was incorporated. The electrical stimulation therapy utilized a postoperative anal rehabilitation protocol, with stimulation intensity progressively adjusted according to the patient’s tolerance. For patients with extremely low resting anal pressure, the duration of electrical stimulation therapy was appropriately extended.(Fig. 5)

Figure 5.

Biofeedback electrical stimulation therapy device.

Under the one-on-one verbal guidance of the same trainer, the patient performed biofeedback training in a standing position. The patient followed voice prompts and observed changes in the electromyographic curve to alternately contract and relax the anal sphincter. Typically, the patient maintained a contraction for 10 s followed by a relaxation for 10 s, with thirty repetitions constituting one treatment session. Electrical stimulation therapy was administered during the intervals between biofeedback training sessions. The patient assumed a left lateral decubitus position, and a current of 10-40 Hz was applied to stimulate the nervous system of the anus, rectum, and pelvic floor muscles, enhancing the recovery of sensory nerve function. Each electrical stimulation session lasted 20 min.

Following the treatment sessions, the patient was instructed to perform gracilis muscle training (Kegel exercises) at home. The patient was advised to adopt positions such as standing, supine, or sitting to perform anal sphincter contraction and relaxation exercises. The patient was instructed to maximally contract the anal sphincter for 5-10 s, followed by a 10-s relaxation, constituting one repetition. The patient performed twenty sets daily, with ten repetitions per set, and the regimen was adjusted on the basis of the patient’s biofeedback training progress.

The detailed training regimen is summarized in Table 1. During the biofeedback training period, anorectal manometry was mainly used for anal function assessment, which showed significant improvement compared to the pre-training level (Figs 3 and 4). After a comprehensive evaluation, the patient underwent stoma reversal on 25 July 2024. Currently, the patient exhibits satisfactory anal function, as evidenced by manometry and anal function scores (Williams A, Wenxer score 8).

Table 1.

Individualized intensive biofeedback electrical stimulation training regimen

Training level	Time (day)	Date	Number of treatment courses
Pre-intermediate level	5	28.04-07.05	10
Intermediate-advanced level	25	08.05-10.06	50
Advanced level	14	11.06-28.06	28

Figure 3.

Comparison of anorectal manometry results 20 days after extended radical resection of rectal cancer and 50 days after ileostomy retraction. (A) Anorectal manometry at rest in early stage after extended radical resection for rectal cancer; (B) Anorectal manometry at anal contraction in early stage after extended radical resection for rectal cancer; (C) Anorectal manometry results at rest in patients after ileostomy retraction; (D) Anorectal manometry results at anal contraction in patients after ileostomy retraction.

Figure 4.

Dynamic change line chart of postoperative anorectal manometry results for patients.

Discussion

For low LARC with the lower edge of the tumor located less than 5 cm from the anal verge, abdominoperineal resection (APR) is the standard radical surgical approach^[7]. However, the permanent colostomy associated with APR often leads to stoma-related complications^[8,9], urogenital dysfunction, the need for long-term stoma care, and persistent psychological stress, all of which significantly impair patients’ postoperative quality of life^[10–12]. Consequently, many patients express a strong desire for sphincter preservation before operation^[13,14]. Nevertheless, the decision to perform sphincter-preserving operation for LARC remains controversial, primarily due to concerns regarding the oncological radicality of tumor resection and the challenge of reconstructing the anal sphincter after resection of the external anal sphincter and puborectalis muscle. Currently reported methods for anal reconstruction include internal anal sphincter replacement with demucosated colonic plication^[15], gracilis muscle transplantation for anal reconstruction^[16], and electrically stimulated gracilis neosphincter reconstruction^[17,18]. However, ensuring that the reconstructed anus achieves satisfactory functional outcomes is not only a critical measure of the success of anal reconstruction but also a technical challenge.

The gracilis muscle is an ideal donor for transplantation due to its rich blood supply, long neurovascular pedicle, superficial anatomical location, high survival rate, strong resistance to infection, and minimal impact on lower limb function after harvest^[19]. Numerous studies have confirmed that the gracilis muscle is a voluntary muscle composed primarily of fast-twitch, fatigue-prone type II skeletal muscle fibers. Unlike the anal sphincter, which consists of fatigue-resistant type I muscle fibers, the gracilis muscle lacks the sustained, fatigue-resistant contraction capability required for optimal postoperative fecal continence^[20]. However, research has demonstrated that the characteristics of type I muscle fibers, which are maintained by distinct enzymatic and metabolic profiles compared to type II fibers, can be transformed through long-term training or continuous bioelectrical stimulation^[21]. Therefore, biofeedback electrical stimulation training following gracilis muscle transplantation for anal reconstruction is crucial for the recovery of postoperative anal function^[22] (Fig. 5). It not only promotes the transformation of type II muscle fibers into fatigue-resistant type I fibers but also enhances the restoration of neorectal sensation^[23] and the development of gracilis sphincter function^[24]. Although some researchers have applied biofeedback therapy to patients after gracilis muscle transplantation for anal reconstruction, the training methods employed have been relatively uniform and lack individualized regimens tailored to the specific characteristics of each patient^[25,26].

Unlike traditional biofeedback training regimens for fecal incontinence, which typically involve weekly sessions lasting 30-60 min^[27], an individualized and intensive biofeedback-electrical stimulation protocol was implemented in this case. First, we incorporated electrical stimulation therapy into the regimen^[28]. For patients with extremely low resting anal pressure, we extended the duration of electrical stimulation therapy^[29]. This approach not only aids in the restoration of impaired anorectal sensation^[30] but also enhances the coordination of defecation^[31]. Second, we designed a stepwise, personalized biofeedback training plan on the basis of the average slow-twitch fiber activity (measured in uV) detected during the initial biofeedback session^[32]. During the intermediate and advanced stages, we gradually increased the training intensity for both slow and fast-twitch muscle fibers, comprehensively improving the strength, speed, and endurance of the neosphincter^[33]. Third, we intensified the frequency and duration of the biofeedback training sessions. Studies have shown a positive dose-response relationship between the number of biofeedback sessions and therapeutic efficacy for fecal incontinence^[34], a finding supported by the outcomes observed in this case. Additionally, during our clinical practice, we observed that biofeedback training in a standing position is more effective for patients who have undergone gracilis muscle transplantation for anal reconstruction. This may be attributed to the reduced interference from the contraction of lateral thigh muscle groups, allowing patients to better control and strengthen the anal sphincter function of the transplanted gracilis muscle.

Our case report has several limitations. Firstly, this study is a single case report and is easily influenced by individual differences. In addition, due to limited relevant research, it cannot be compared with other standardized treatment; Secondly, this case only reported short-term oncological and functional results, and long-term efficacy needs further follow-up. Furthermore, although the individualized training program has been relatively refined, some rehabilitation parameter settings still rely on subjective clinical judgment. In addition, intensive training has high requirements for patient compliance and tolerance, which will affect the standardization and generalizability of the program. Finally, this study emphasizes the potential mechanisms of muscle fiber transformation, but further mechanistic research is needed to confirm these inferences.

Conclusion

This case highlights that gracilis muscle transplantation for anal reconstruction is an effective approach for achieving functional sphincter preservation in patients with low LARC. Furthermore, individualized intensive biofeedback-electrical stimulation training is a highly effective therapeutic strategy for enhancing postoperative anal function and improving quality of life in patients who have undergone gracilis muscle transplantation for anal reconstruction.

Ethical approval

The studies involving humans were approved by Yangpu Hospital, Tongji University School of Medcine. The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study. Written informed consent was obtained from the individual(s) for the publication of any potentially identifiable images or data included in this article.

Consent Statement

Written informed consent was obtained from the patient for publication of this case report and accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal on request.

Source of Funding

Not available.

Author Contributions

Conceptualization, H.D., H.J., Y.F., A.L., Z.L., Y.C., H.L.; Writing – original draft, H.D.; Writing - review & editing, H.J., A.L.; Investigation, H.D., Z.L., Y.C.; Supervision, S.F., M.L.

Conflicts of interest disclosure

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Guarantor

Moubin Lin, MD.

Research Registration Unique Identifying Number (UIN)

Not available.

Provenance and peer review

Not commissioned, externally peer-reviewed.

Availability of data and materials

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.