Study design, materials and methods
A descriptive and analytical retrospective cohort study was conducted. Patients referred to the anorectal physiology unit of the coloproctology service of a high complexity hospital in latin america for severe low anterior resection syndrome who underwent specific electrostimulation between 2018 and 2023 were included. Patients with metastasis, neoplastic recurrence and less than 12 months after surgery were excluded. Sociodemographic variables, tumor characteristics, symptoms at the time of consultation, and extension studies (high-resolution manometry and endoanal ultrasound) were analyzed. The Low Anterior Resection Syndrome Score (LARS-S) and the Jorge Wexner Fecal Incontinence Score (Wexner) were used to measure quality of life before and after treatment.
Patients were placed in the left lateral decubitus position for specific electrostimulation therapy. An anal electrode connected to an electrical generator and a computer with software were used. Chattanooga Intelect advanced equipment was used. Each session lasted 20 minutes and took place once a week. Patients received electrical stimulation and biofeedback once per week for 12 ambulatory sessions.
The electrostimulation parameters were two-pole interferential energy (IF-2: fixed pulse 50 Hz, frequency 2500 Hz) and surface PTN (200 mg, frequency 20 Hz) for fecal incontinence; intracavitary asymmetric biphasic energy (80 ms, 5 Hz) for fecal urgency and intracavitary or surface symmetric biphasic energy (100 ms, 80 Hz) for pain, the voltage intensities were adjusted according to tolerance. Immediate biofeedback was performed with a Myotrac device connected to the endoanal electrode and a hip patch, using multimedia biofeedback software (BioGraph) to record electrical activity during effort and relaxation, visually and acoustically (verbalized by the attending physician with emphasis on the maneuver), for 10 min. The electrostimulation parameters are shown in Figure 1.
Statistical analysis was performed with Rstudio version 2023.06.1. Quantitative variables are expressed in medians and interquartile ranges (IQR). Categorical variables are expressed as percentages and proportions. Statistical comparison between scores before and after electrostimulation therapy was performed using wilcoxon signed rank test with correction for continuity, and a difference of p < 0.05 was considered statistically significant.
Results
Fourteen patients who underwent targeted electrical stimulation for severe low anterior resection syndrome were included in the study. The median age was 58 years [IQR 48.5 - 69.5], 78% (11/14) had no comorbidities. All patients had rectal adenocarcinoma confirmed by pathologic examination of surgical specimens, with stages IIIb (4/14), IIIa (2/14), and IIb (2/14) being the most common. The median distance of the tumor from the anal margin was 6 cm [IQR 4 - 9.5].
The most common symptom reported was fecal incontinence, present in 85.7% of patients (12/14), followed by anal pain and fecal urgency in 7.1% (1/14) of patients each. High-resolution manometry studies revealed hyposensitivity in 42.8% (6/14) and hypersensitivity in 28.5% (4/14) of cases. Internal anal sphincter hypotonia was present in 35.7% (5/14) and internal and external anal sphincter hypotonia in 64.3% (9/14) of cases. Rectal ultrasound was performed in 57.4% (8/14) of patients and showed fibrosis due to surgical history in 12.5% (1/8) and anal sphincter solutions in 75% (6/14).
After electrostimulation, 33.3% (4/12) of patients with incontinence reported 90% improvement, 25% (3/12) reported 80% improvement, 25% (3/12) reported 70% improvement, and 16.7% (2/12) reported 60% improvement. The improvement in fecal urgency was 70% and the improvement in anal pain was 60%. The median LARS-S was 41 points [IQR 37 - 41.75] before specific electrostimulation and 18 points [IQR 8.25 - 20] after specific electrostimulation (p < 0.001). The median Wexner was 16 points [IQR 15 - 17] before and 2.50 points [IQR 1.25 - 3.75] after specific electrostimulation (p < 0.001). 2 patients received subsequent electrostimulation with different energy types one after another cycle (12 sessions) for anal pain (80% improvement with 12 sessions), fecal urgency (70% improvement with 8 sessions) and anal incontinence.
Interpretation of results
The development of LARS is multifactorial, and an increasing number of options have been discovered to improve the quality of life of patients with rectal cancer. In our cohort, we found that the use of specific electrostimulation therapy in patients with low anterior resection syndrome could lead to improvement at the clinical level, as demonstrated by improvement in patients' symptoms and in the LARS-S and Wexner questionnaires.
To our knowledge, this is the first Latin American study evaluating the use of specific biofeedback electrostimulation in patients with severe low anterior resection syndrome. In our analysis, using this therapy was associated with at least a 70% improvement in fecal incontinence in 83.3% (10/12) of patients, and improved symptoms in patients with anal pain and fecal urgency. This improvement was also demonstrated by the questionnaires used, and the difference was statistically significant in both instances. In the case of the LARS score, a median decrease of 23 points was found, while in Wexner a decrease of 13.5 points was found, showing a significant difference in quality of life after the application of the therapy.
Currently, level II or B evidence supports the use of biofeedback for fecal incontinence in the short and long term, and suggests that electrostimulation and biofeedback achieve better results when used together, consistent with the results found [1,2]. It should be noted that the use of electrostimulation therapy has previously shown favorable results in cohorts of similar size; for example, in a series of 24 patients with fecal incontinence treated with low-frequency endoanal electrostimulation, a significant improvement in continence scores as well as manometric values was observed [2]. However, larger sample sizes with high levels of evidence are needed to determine the effect of this specific therapy in patients with LARS.