Anatomische Grundlagen der nervenschonenden Rektumchirurgie

Intraoperative pelvic neuromonitoring based on bioimpedance signals: a new method analyzed on 30 patients

PURPOSE

Increasing importance has been attributed in recent years to the preservation of the pelvic autonomic nerves during rectal resection to achieve better functional results. In addition to improved surgical techniques, intraoperative neuromonitoring may be useful.

METHODS

This single-arm prospective study included 30 patients who underwent rectal resection performed with intraoperative neuromonitoring by recording the change in the tissue impedance of the urinary bladder and rectum after stimulation of the pelvic autonomic nerves. The International Prostate Symptom Score, the post-void residual urine volume and the Low Anterior Resection Syndrome Score (LARS score) were assessed during the 12-month follow-up period.

RESULTS

A stimulation-induced change in tissue impedance was observed in 28/30 patients (93.3%). In the presence of risk factors such as low anastomosis, neoadjuvant radiotherapy and a deviation stoma, an average increase of the LARS score by 9 points was observed 12 months after surgery (p = 0,04). The function of the urinary bladder remained unaffected in the first week (p = 0,7) as well as 12 months after the procedure (p = 0,93).

CONCLUSION

The clinical feasibility of the new method for pelvic intraoperative neuromonitoring could be verified. The benefits of intraoperative pelvic neuromonitoring were particularly evident in difficult intraoperative situations with challenging visualization of the pelvic nerves.

Automatic muscle impedance and nerve analyzer (AMINA) as a novel approach for classifying bioimpedance signals in intraoperative pelvic neuromonitoring

Frequent complications arising from low anterior resections include urinary and fecal incontinence, as well as sexual disorders, which are commonly associated with damage to the pelvic autonomic nerves during surgery. To assist the surgeon in preserving pelvic autonomic nerves, a novel approach for intraoperative pelvic neuromonitoring was investigated that is based on impedance measurements of the innervated organs. The objective of this work was to develop an algorithm called AMINA to classify the bioimpedance signals, with the goal of facilitating signal interpretation for the surgeon. Thirty patients included in a clinical investigation underwent nerve-preserving robotic rectal surgery using intraoperative pelvic neuromonitoring. Contraction of the urinary bladder and/or rectum, triggered by direct stimulation of the innervating nerves, resulted in a change in tissue impedance signal, allowing the nerves to be identified and preserved. Impedance signal characteristics in the time domain and the time-frequency domain were calculated and classified to develop the AMINA. Stimulation-induced positive impedance changes were statistically significantly different from negative stimulation responses by the percent amplitude of impedance change Amax in the time domain. Positive impedance changes and artifacts were distinguished by classifying wavelet scales resulting from peak detection in the continuous wavelet transform scalogram, which allowed implementation of a decision tree underlying the AMINA. The sensitivity of the software-based signal evaluation by the AMINA was 96.3%, whereas its specificity was 91.2%. This approach streamlines and automates the interpretation of impedance signals during intraoperative pelvic neuromonitoring.

Quality of Life in Patients With Rectal Resections and End-to-End Primary Anastomosis Using a Standardized Perioperative Pathway

Objectives: Lower rectal resection is associated with a high rate of postoperative complications and, therefore, adversely impacts the postoperative health-related quality of life (QoL). Though sporadically practiced in different centers, there is no standard perioperative protocol for the management of patients with rectal growths. The aim of this analysis is to evaluate the patient-reported outcomes after low rectal resections followed by an end-to-end-reconstruction and temporary covering ileostomy using a multidisciplinary fail-safe-concept.

Methods: Between 2015 and 2020, we evaluated patient reported outcomes after open and laparoscopic rectal resections with end-to-end reconstruction with a primary straight anastomosis using a standardized perioperative pathway All patients with stoma were excluded from the study. The data for the QoL of patients was collected using the established Low Anterior Resection Syndrome (LARS)-score and the EORTC-C30 and CR-29 questionnaires at a single postoperative timepoint.

Results: We recruited 78 stoma-free patients for this analysis. Of 78 patients included in the study, 87.2% were operated laparoscopically and the mean global health status was 67.95 points, while a major LARS was detected in 48 (61.5%) patients. No anastomotic leakage (AL) occurred within the study cohort. There was no significant change in the LARS-score or the global health status depending on the follow-up-period.

Conclusion: This study shows that good QoL and functional outcomes with no AL are achievable following end-to-end straight anastomosis using a standardized perioperative surgical fail-safe protocol procedure.

[Low anterior resection syndrome-Causes and treatment approaches]

BACKGROUND

With improvement of the oncological prognosis and more sphincter-preserving procedures for rectal cancer of the lower third, the functional sequelae of anterior rectal resection become more and more predominant and are summarized under the term low anterior resection syndrome (LARS).

MATERIAL AND METHODS

In this narrative review the causes, associated factors, prevalence, diagnostics and treatment strategies are presented based on an evaluation of the international literature.

RESULTS

The central role of the rectum in the physiology of defecation and continence explains the frequency of symptoms following anterior rectal resection. In an unselected patient population a major LARS is to be expected in approximately 40% and a minor LARS in approximately 20%. The most important factor is the length of the remaining rectal stump. The diagnosis of LARS is made clinically and can be quantified by scores, especially by the LARS score. Treatment options range from patient counselling to stoma construction and a symptom-related, stepwise approach is generally accepted.

CONCLUSION

While the evidence for the causes, the quantification and determination of associated factors of LARS is good, the treatment options are based either on experience or on only few studies.

Perirectal Fascial Anatomy: New Insights Into an Old Problem

BACKGROUND

The architecture of perirectal fasciae is complex as mirrored by different anatomical concepts.

OBJECTIVE

This study aimed to perform a comprehensive visualization of perirectal fasciae to facilitate strategies of rectal surgery such as total mesorectal excision, intersphincteric resection, and transanal total mesorectal excision.

DESIGN

Macroscopic dissection and histologic studies of perirectal fasciae and autonomic pelvic nerves were performed.

SETTINGS

This study was conducted in a university laboratory of macroscopic and microscopic anatomy.

PATIENTS

Thirteen (5 female) pelvic specimens were obtained from body donors (67-92 years of age).

MAIN OUTCOME MEASURES

The primary outcomes measured were the photodocumentation of perirectal fasciae, spaces and fusion zones, and histologic and immunohistochemical analysis of key structures.

RESULTS

The retrorectal space is a mesofascial interface between the mesorectal fascia and the parietal pelvic fascia. The parietal pelvic fascia is composed of 2 lamellae ensheathing the autonomic pelvic nerves. The outer lamella of the parietal pelvic fascia and the presacral fascia confine the presacral space. The presacral fascia covers the median sacral blood vessels. Approximately at the fourth sacral vertebra, all fascial layers fuse in the midline and are densely connected to the posterior rectal wall via the rectosacral ligament. The parietal pelvic fascia fuses with the pubococcygeal and longitudinal rectal muscles at the anorectal junction. Anterolaterally, the neurovascular bundles are closely related to this fascial fusion zone and the rectogenital septum.

LIMITATIONS

Because of the increased age of the body donors, the findings may be subjected to age-related degenerative processes.

CONCLUSIONS

The 2 lamellae of the parietal pelvic fascia and the fascial fusion zones are key structures of perirectal anatomy. For autonomic nerve preservation, the recognition of the inner lamella of the parietal pelvic fascia is crucial. To avoid inadvertent rectal perforation or accidental presacral dissection, the rectosacral ligament must be identified and transected for complete rectal mobilization. See Video Abstract at http://links.lww.com/DCR/B389. ANATOMÍA FASCIAL PERIRRECTAL: NUEVOS CONCEPTOS SOBRE UN ANTIGUO PROBLEMA: La arquitectura de las fascias perirrectales es compleja, reflejada por distintos conceptos anatómicos.Integración de conceptos sobre las fascias perirrectales para facilitar las estrategias de cirugía rectal, como la escisión mesorrectal total, la resección interesfintérica y la escisión mesorrectal total transanal.Disección macroscópica y estudios histológicos de fascias perirrectales y nervios pélvicos autonómicos.Laboratorio universitario de anatomía macroscópica y microscópica.Trece (5 mujeres) muestras pélvicas obtenidas de donantes de cuerpo (67-92 años).Foto documentación de fascias perirrectales, espacios y zonas de fusión, análisis histológico e inmunohistoquímico de estructuras claves.El espacio retrorectal es una interfaz mesofascial entre la fascia mesorrectal y la fascia pélvica parietal. Este último se compone de dos láminas que envuelven los nervios pélvicos autonómicos. La lámina externa de la fascia pélvica parietal y la fascia presacra definen el espacio presacro. La fascia presacra cubre los vasos sanguíneos sacros medianos. Aproximadamente en la cuarta vértebra sacra, todas las capas fasciales se unen en la línea media y están densamente conectadas a la pared rectal posterior a través del ligamento rectosacro. La fascia pélvica parietal se une con los músculos rectal pubococcígeo y longitudinal en la unión anorrectal. Anterolateralmente, los haces neurovasculares están estrechamente relacionados con esta zona de fusión fascial y el tabique rectogenital.Debido al aumento de la edad de los donantes de cuerpos, los hallazgos pueden estar sujetos a procesos degenerativos relacionados con la edad.Las dos láminas de la fascia pélvica parietal y las zonas de fusión fascial son estructuras claves de la anatomía perirrectal. Para la preservación del nervio autónomo de nervios pélvicos autonómicos, el reconocimiento de la lámina interna de la fascia pélvica parietal es importante. Para evitar la perforación rectal inadvertida o la disección presacra accidental, el ligamento rectosacro debe ser identificado y seccionado para una movilización rectal completa. Consulte Video Resumen en http://links.lww.com/DCR/B389.

Intraoperative fluorescence angiography with indocyanine green: retrospective evaluation and detailed analysis of our single-center 5-year experience focused on colorectal surgery

Objectives

Assessing bowel perfusion with indocyanine green fluorescence angiography (ICG-FA) shows positive effects on anastomotic healing in colorectal surgery.

Methods

A retrospective evaluation of 296 colorectal resections where we performed ICG-FA was undertaken from January 2014 until December 2018. Perfusion of the bowel ends measured with ICG-FA was compared to the visual assessment before and after performing the anastomosis. According to the observations, the operative strategy was confirmed or changed. Sixty-seven low anterior rectal resections (LARs) and 76 right hemicolectomies were evaluated statistically, as ICG-FA was logistically not available for every patient in our service and thus a control group for comparison resulted.

Results

The operative strategy based on the ICG-FA results was changed in 48 patients (16.2%), from which only one developed an anastomotic leakage (AL) (2.1%). The overall AL rate was calculated as 5.4%. Within the 67 patients with LAR, the strategy was changed in 11 patients (16.4%). No leakage was seen in those. In total three AL happened (4.5%), which was three times lower than the AL rate of 13.6% in the control group but statistically not significant. From the 76 right hemicolectomies a strategy change was undertaken in 10 patients (13.2%), from which only one developed an AL. This was the only AL reported in the whole group (1.3%), which was six times lower than the leakage rate of the control group (8.1%). This difference was statistically significant (p=0.032).

Conclusions

Based on the positive impact by ICG-FA on the AL rate, we established the ICG-FA into our clinical routine. Although randomized studies are still missing, ICG-FA can raise patient safety, with only about 10 min longer operating time and almost no additional risk for the patients.

Outcome of bowel function following anterior resection for rectal cancer-an analysis using the low anterior resection syndrome (LARS) score

PURPOSE

Severity of anorectal dysfunction after low anterior resection is associated with various patient- and treatment-related factors. We aimed to quantify anorectal dysfunction after treatment for rectal cancer using the low anterior resection syndrome (LARS) score.

METHODS

We retrieved from a prospective database 331 eligible patients on whom anterior resection for rectal cancer had been performed from 2000 to 2014. All patients were sent a LARS score accompanied by a supplementary questionnaire. Response rate was 78.8% (261 patients). The main outcome measure was the relation of the LARS score to potentially associated patient and treatment factors. Secondary endpoints were further measures that reflect anorectal dysfunction, e.g., Vaizey score.

RESULTS

Overall, 144 (55.2%) patients exhibited scores > 20 reflecting minor (n = 51 (19.5%)) or major (n = 93 (35.6%)) LARS. A significant difference for scores > 20 was found for intersphincteric resection (IR, 73.2% affected patients) compared to total mesorectal excision (TME, 58.4%) and partial mesorectal excision (PME, 38.0%, p = 0.001). Radio(chemo)therapy resulted in LARS scores > 20 in 64.6% of patients compared to 43.1% in patients without irradiation (p = 0.001). Type of procedure (TME and IR as compared to PME), radio(chemo)therapy, and younger age were independently associated with LARS in logistic regression analysis. However, younger age remained the only independent factor for higher scores after exclusion of PME.

CONCLUSIONS

The LARS score identified a substantial proportion of patients after surgery for rectal cancer with anorectal dysfunction. The extent of surgical procedure is independently associated with the severity of symptoms whereas the role of radiotherapy needs further assessment.