Internal anal sphincter parasympathetic-nitrergic and sympathetic-adrenergic innervation: a 3-dimensional morphological and functional analysis

Low Anterior Resection Syndrome and Quality of Life of Patients After Sphincter Preservation Surgery: A Prospective Study

Background After anterior resection (AR), one of the most debilitating complications is low anterior resection syndrome (LARS) seen in about 64% of patients. The severity of the LARS score was significantly correlated with neoadjuvant treatment, the extent of rectal surgery, complication by the anastomotic leak, female gender, and age < 64 years. In this study, we analyzed the impact of various clinical factors on LARS and also the various domains of quality of life (QoL). Purpose To assess the incidence of LARS in patients undergoing sphincter-sparing surgery for rectal cancer after the patient starts long-term defecating per anus, change in the QoL, and relation to LARS and factors affecting it. Methods One year before, 72 patients who had undergone AR in the Regional Cancer Centre were interviewed by a trained interviewer and data was collected from the file. The questionnaires used were the Wexner Incontinence score, LARS Malayalam Questionnaire, and European Organisation For Research and Treatment of Cancer (EORTC) QLQ C30 Malayalam translations. Statistical measures The LARS score was used to categorize patients into three grades. The scores were compared with clinical and social factors using the χ2 test for association. Continuous variables were compared by the Spearman Rho test. Results Details of patients were studied (male: 55.6% (40) and female: 44.4% (32)). Fifty patients underwent low anterior resection (LAR). The mean LARS score was 25.61, with 47.2% of patients having severe LARS score. The mean Wexner score was 6.84. The relation with type of surgery, approach (laparoscopic vs open), or type of neoadjuvant therapy was not found to be significant. A higher LARS score did not impact overall QoL as assessed by FACT-C. Insomnia and diarrhea symptoms scores were significantly worsened. The pain score was worse for those undergoing stapler anastomosis. Wexner's score was worse for those who had received adjuvant chemotherapy. Role functioning score was better for AR compared to low anterior resection (LAR). Only distance from the anal verge was found to be a significant cause of LARS and was negatively correlated. Discussion LARS of severe degrees were seen in most patients. No modifiable risk factors were significantly found to affect the chance of LARS. However, LARS did not have a significant impact on QoL, neither did the type of surgery. So sphincter preservation can be offered to the patients, but all patients undergoing LAR should be counseled well about the risk of LARS before surgery.

Interstitial cells of Cajal and human colon motility in health and disease

Our understanding of human colonic motility, and autonomic reflexes that generate motor patterns, has increased markedly through high-resolution manometry. Details of the motor patterns are emerging related to frequency and propagation characteristics that allow linkage to interstitial cells of Cajal (ICC) networks. In studies on colonic motor dysfunction requiring surgery, ICC are almost always abnormal or significantly reduced. However, there are still gaps in our knowledge about the role of ICC in the control of colonic motility and there is little understanding of a mechanistic link between ICC abnormalities and colonic motor dysfunction. This review will outline the various ICC networks in the human colon and their proven and likely associations with the enteric and extrinsic autonomic nervous systems. Based on our extensive knowledge of the role of ICC in the control of gastrointestinal motility of animal models and the human stomach and small intestine, we propose how ICC networks are underlying the motor patterns of the human colon. The role of ICC will be reviewed in the autonomic neural reflexes that evoke essential motor patterns for transit and defecation. Mechanisms underlying ICC injury, maintenance, and repair will be discussed. Hypotheses are formulated as to how ICC dysfunction can lead to motor abnormalities in slow transit constipation, chronic idiopathic pseudo-obstruction, Hirschsprung's disease, fecal incontinence, diverticular disease, and inflammatory conditions. Recent studies on ICC repair after injury hold promise for future therapies.

The Sphincter of O'Beirne - Part 1: Study of 18 Normal Subjects

BACKGROUND

Gastroenterologists have ignored or emphasized the importance of the rectosigmoid junction in continence or constipation on and off for 200 years. Here, we revisit its significance using high-resolution colonic manometry.

METHODS

Manometry, using an 84-channel water-perfused catheter, was performed in 18 healthy volunteers.

RESULTS

The rectosigmoid junction registers as an intermittent pressure band of 26.2 ± 7.2 mmHg, or intermittent phasic transient pressure increases at a dominant frequency of 3 cpm and an amplitude of 28.6 ± 8.6 mmHg; or a combination of tone and transient pressures, at a single sensor, 10-17 cm above the anal verge. Features are its relaxation or contraction in concert with relaxation or contraction of the anal sphincters when a motor pattern such as a high-amplitude propagating pressure wave or a simultaneous pressure wave comes down, indicating that such pressure increases or decreases at the rectosigmoid junction are part of neurally driven programs. We show that the junction is a site where motor patterns end, or where they start; e.g. retrogradely propagating cyclic motor patterns emerge from the junction.

CONCLUSIONS

The rectosigmoid junction is a functional sphincter that should be referred to as the sphincter of O'Beirne; it is part of the "braking mechanism," contributing to continence by keeping content away from the rectum. In an accompanying case report, we show that its excessive presence in a patient with severe constipation can be a primary pathophysiology.

The Sphincter of O'Beirne-Part 2: Report of a Case of Chronic Constipation with Autonomous Dyssynergia

BACKGROUND

Chronic constipation can have one or more of many etiologies, and a diagnosis based on symptoms is not sufficient as a basis for treatment, in particular surgery.

AIM

To investigate the cause of chronic constipation in a patient with complete absence of spontaneous bowel movements.

METHODS

High-resolution colonic manometry was performed to assess motor functions of the colon, rectum, the sphincter of O'Beirne and the anal sphincters.

RESULTS

Normal colonic motor patterns were observed, even at baseline, but a prominent high-pressure zone at the rectosigmoid junction, the sphincter of O'Beirne, was consistently present. In response to high-amplitude propagating pressure waves (HAPWs) that were not consciously perceived, the sphincter and the anal sphincters would not relax and paradoxically contract, identified as autonomous dyssynergia. Rectal bisacodyl evoked marked HAPW activity with complete relaxation of the sphincter of O'Beirne and the anal sphincters, indicating that all neural pathways to generate the coloanal reflex were intact but had low sensitivity to physiological stimuli. A retrograde propagating cyclic motor pattern initiated at the sphincter of O'Beirne, likely contributing to failure of content to move into the rectum.

CONCLUSIONS

Chronic constipation without the presence of spontaneous bowel movements can be associated with normal colonic motor patterns but a highly exaggerated pressure at the rectosigmoid junction: the sphincter of O'Beirne, and failure of this sphincter and the anal sphincters to relax associated with propulsive motor patterns. The sphincter of O'Beirne can be an important part of the pathophysiology of chronic constipation.

Precision Surgery In Rectal Resection With Hyperspectral and Fluorescence Imaging And Pelvic Intraoperative Neuromonitoring (With Video)

Oncologic visceral surgery has recently been revolutionized by robotics, artificial intelligence (AI), sparing of functionally important structures and innovative intraoperative imaging tools. These techniques enable new dimensions of precision surgery and oncology. Currently, data-driven, cognitive operating rooms are standing at the forefront of the latest technical and didactic developments in abdominal surgery. Rectal low anterior resection with total mesorectal excision (TME) for lower- and middle-third rectal cancer is a challenging operation due to the narrow pelvis and the tender guiding structures. Thus, new approaches have been needed to simplify the procedure and to upgrade the results. The combination of robotics with pelvic intraoperative neuromonitoring (pIONM) and new possibilities of visualization, such as multi- and hyperspectral imaging (MSI / HSI) or fluorescence imaging (FI) with indocyanine green (ICG) is a forward-looking modality to enhance surgical precision and reduce postoperative complications while improving oncologic and functional outcomes with a better quality of life. The aim of our video-paper is to show how to achieve maximum precision by combining robotic surgery with pelvic intraoperative neuromonitoring and new imaging devices for rectal cancer.

Introduction and validation of a new semi-automated method to determine sympathetic fiber density in target tissues

In recent years, the role of sympathetic nervous fibers in chronic inflammation has become increasingly evident. At the onset of inflammation, sympathetic activity is increased in the affected tissue. However, sympathetic fibers are largely absent from chronically inflamed tissue. Apparently, there is a very dynamic relationship between sympathetic innervation and the immune system in areas of inflammation, and hence a rapid and easy method for quantification of nerve fiber density of target organs is of great value to answer potential research questions. Currently, nervous fiber densities are either determined by tedious manual counting, which is not suitable for high throughput approaches, or by expensive automated processes relying on specialized software and high-end microscopy equipment. Usually, tyrosine hydroxylase (TH) is used as the marker for sympathetic fibers. In order to overcome the current quantification bottleneck with a cost-efficient alternative, an automated process was established and compared to the classic manual approach of counting TH-positive sympathetic fibers. Since TH is not exclusively expressed on sympathetic fibers, but also in a number of catecholamine-producing cells, a prerequisite for automated determination of fiber densities is to reliably distinct between cells and fibers. Therefore, an additional staining using peripherin exclusively expressed in nervous fibers as a secondary marker was established. Using this novel approach, we studied the spleens from a syndecan-3 knockout (SDC3KO) mouse line, and demonstrated equal results on SNS fiber density for both manual and automated counts (Manual counts: wildtype: 22.57 +/- 11.72 fibers per mm²; ko: 31.95 +/- 18.85 fibers per mm²; p = 0.05; Automated counts: wildtype: 31.6 +/- 18.98 fibers per mm²; ko: 45.49 +/- 19.65 fibers per mm²; p = 0.02). In conclusion, this new and simple method can be used as a high-throughput approach to reliably and quickly estimate SNS nerve fiber density in target tissues.

Anterior resection syndrome: What should we tell practitioners and patients in 2018?

Multidisciplinary management of infra-peritoneal rectal cancer has pushed back the frontiers of sphincter preservation, without impairment of carcinological outcome. However, functional intestinal sequelae, grouping together several symptoms known under the name of anterior resection syndrome (ARS), have emerged and become an increasingly frequent concern for both patients and physicians. The pathophysiology is complex: ARS is a combination in various degrees of stool frequency, incontinence for flatus and/or stools, urgency, and disorders in discrimination and evacuation. The "Low Anterior Resection Score" (LARS), validated in 2012, is currently used to evaluate the severity of ARS and its impact on quality of life. While ARS can show improvement over the first two years, symptoms persist for longer than two years in nearly 60% of patients and in half of these patients, ARS is considered severe. The most frequently reported independent risk factors of severe ARS include neo-adjuvant radiation therapy, the extent of resection (total mesorectal excision that includes inter-sphincteric resection), absence of colonic pouch and anastomotic leak. In the absence of surgical complications and/or local recurrence, physicians can draw from a wide therapeutic armamentarium in order to improve the functional outcome of patients, including diet and lifestyle modifications, gut motility regulators, multimodal rehabilitation (biofeedback, electro-stimulation) and sacral nerve modulation. Permanent colostomy is an alternative of last resort, proposed only when all other solutions fail. A better understanding of the natural history of ARS, its risk factors as well as the array of therapeutic alternatives should provide better patient information and optimize management.

Internal anal sphincter nerves - a macroanatomical and microscopic description of the extrinsic autonomic nerve supply of the internal anal sphincter

AIM

The internal anal sphincter (IAS) contributes substantially to anorectal functions. While its autonomic nerve supply has been studied at the microscopic level, little information is available concerning the macroscopic topography of extrinsic nerve fibres. This study was designed to identify neural connections between the pelvic plexus and the IAS, provide a detailed topographical description, and give histological proof of autonomic nerve tissue.

METHODS

Macroscopic dissection of pelvic autonomic nerves was performed under magnification in seven (five male, two female) hemipelvises obtained from body donors (67-92 years). Candidate structures were investigated by histological and immunohistochemical staining protocols to visualize nerve tissue.

RESULTS

Nerve fibres could be traced from the anteroinferior edge of the pelvic plexus to the anorectal junction running along the neurovascular bundle anterolaterally to the rectum and posterolaterally to the prostate/vagina. Nerve fibres penetrated the longitudinal rectal muscle layer just above the fusion with the levator ani muscle (conjoint longitudinal muscle) and entered the intersphincteric space to reach the IAS. Histological and immunohistochemical findings confirmed the presence of nerve tissue.

CONCLUSIONS

Autonomic nerve fibres supplying the IAS emerge from the pelvic plexus and are distinct to nerves entering the rectum via the lateral pedicles. Thus, they should be classified as IAS nerves. The identification and precise topographical location described provides a basis for nerve-sparing rectal resection procedures and helps to prevent postoperative functional anorectal disorders.

Total mesorectal excision for cancer: histological and immunohistochemical evidence of nerve removal and risk-factor analysis

AIM

Whether or not nerve-sparing rectal-cancer surgery can effectively prevent removal of the pelvic autonomic nerves has not been substantiated microscopically. We aimed to analyse the quality of nerve preservation in female patients by quantifying residual nerve fibres in total mesorectal excision specimens, to analyse pro-erectile function of the nerve fibres removed and to determine risk factors for pelvic denervation.

METHOD

Serial transverse sections from female patients, 64 ± 18 years of age, were studied after the mesorectal fascia was inked and studied histologically [using anti-S100 and anti-neuronal nitric oxide synthase (nNOS) antibodies]. Nerve fibres located within 1 mm of the inked surface were counted and analysed according to type of surgery, tumour location, pT stage, circumferential resection margin and the necessity for a posterior colpectomy.

RESULTS

Twelve specimens were analysed. Per specimen, the mean number of nerve-fibre sections outside the mesorectum was 5.3 ± 3.6 (range: 1-12). The mean number of fibres per specimen was 6.4 ± 4.1 in patients having a low-rectal tumour and 4.4 ± 2.9 in those with mid or higher rectal tumours (P = 0.42). The mean number of fibres was higher (9.2) for T4 tumours than for T2/T3 tumours (5.0 ± 3.5), but this difference was not statistically sigmificant (P = 0.25). Patients having abdominoperineal excision, a posterior colpectomy or a circumferential resection margin of less than 1 mm had significantly more nerve fibres in the specimen (10.6 ± 1.9 vs 4.4 ± 2.8; P = .041). Fibres localized at the anterolateral rectum corresponded to branches of the neurovascular bundle, expressing rich pro-erectile activity (positive anti-nNOS immunostaining).

CONCLUSION

The neurovascular bundle is a key risk zone for pelvic denervation during total mesorectal excision. Abdominoperineal excision, posterior colpectomy and an invaded circumferential resection margin are associated with perineal denervation.

Surgeons' assessment of internal anal sphincter nerve supply during TaTME - inbetween expectations and reality

Background: Intraoperative identification of nerve fibers heading from the inferior rectal plexus (IRP) to the internal anal sphincter (IAS) is challenging. The transanal total mesorectal excision (TaTME) is said to better preserve pelvic autonomic nerves. The aim of this study was to investigate the nerve identification rates during TaTME by transanal visual and electrophysiological assessment.

Material and methods: A total of 52 patients underwent TaTME for malignant conditions. The IRP with its posterior branches to the IAS and the pelvic splanchnic nerves (PSN) were visually assessed in 20 patients (v-TaTME). Electrophysiological nerve identification was performed in 32 patients using electric stimulation under processed electromyography of IAS (e-TaTME).

Results: The indication profile for TaTME was comparable between the v-TaTME and the e-TaTME group. The identification of IRP was more meaningful under electrophysiological assessment than under visual assessment for the left pelvic side (81% vs. 45%, p = 0.008) as well as the right pelvic side (78% vs. 45%, p = 0.016). The identification rates for PSN did not significantly differ between both groups, respectively (81% vs. 75%, p = 0.420 and 84% vs. 70%, p = 0.187).

Conclusions: The transanal approach facilitated visual identification of IAS nerve supply. In combination with electrophysiological nerve assessment the identification rate almost doubled. For further insights functional data are needed.

Composite nerve fibers in the hypogastric and pelvic splanchnic nerves: an immunohistochemical study using elderly cadavers

To determine the proportion of nerve fibers in the hypogastric nerve (HGN) and pelvic splanchnic nerve (PSN), small tissue strips of the HGN and PSN from 12 donated elderly cadavers were examined histologically. Immunohistochemistry for neuronal nitric oxide synthase (NOS), vasoactive intestinal peptide (VIP), and tyrosine hydroxylase (TH) was performed. More than 70% of fibers per bundle in the HGN were positive for TH at the level of the sacral promontory. In addition, NOS- (negative) and/or VIP+ (positive) fibers were observed in small areas of each nerve bundle, although the proportion of each was usually less than 10%. In the PSN near the third sacral nerve root, the proportion of nerve fibers positive for NOS and/or VIP (or TH) was below 30%. In both the HGN and PSN, the number of VIP+ fibers was usually greater than that of NOS+ fibers, with frequent co-localization of NOS and VIP. More fibers in both nerves were positive for TH than for these other markers. In contrast to pelvic plexus branches, there were no differences in the proportions of NOS+ and VIP+ fibers between nerve bundles in each of the tissue strips. Thus, target-dependent sorting of nerve fibers was not apparent in the HGN at the level of the sacral promontory or in the PSN near the third sacral nerve root. The NOS+ and/or VIP+ fibers in the HGN were most likely ascending postganglionic fibers to the colon, while those in the PSN root may be preganglionic fibers from Onuf's nucleus.

Topography of the extrinsic internal anal sphincter nerve supply during laparoscopic-assisted TAMIS TME: five key zones of risk from the surgeons' view

PURPOSE

Sparing the extrinsic autonomic innervation of the internal anal sphincter during total mesorectal excision is important for the preservation of anal sphincter function. This study electrophysiologically confirmed the topography of the internal anal sphincter nerve supply during laparoscopic-assisted transanal minimally invasive surgery for total mesorectal excision.

METHODS

This prospective study was conducted at two large multispecialty referral centers. Six patients (five males and one female) aged between 45 and 65 years with low rectal cancer (≤5 cm from the anal verge) were enrolled. Surgery was performed under electric stimulation of the pelvic autonomic nerves with observation of the electromyographic signals of the internal anal sphincter.

RESULTS

The minimally invasive transanal surgical approach enabled advantageous visualization of the pelvic autonomic nerves in all patients. In particular, extrinsic innervation to the internal anal sphincter near the levator muscle was consciously spared under electrophysiological confirmation. The evoked absolute electromyographic amplitudes of the internal anal sphincter during transanal minimally invasive surgery were significantly lower than the initial results of the laparoscopic approach [3.7 μV (interquartile range 2.4; 5.7) vs. 4.3 μV (interquartile range 3.1; 8.6); p = 0.002]. Five key zones of risk for pelvic autonomic nerve damage were identified. No complications occurred.

CONCLUSIONS

The electromyographic results of this preliminary study indicate advantages for sparing the internal anal sphincter innervation during transanal minimally invasive mesorectal dissection considering the specific in situ neuroanatomical topography.

Percutaneous nerve evaluation based on electrode placement under control of autonomic innervation

BACKGROUND

Foramen needle electrode placement for percutaneous nerve evaluation (PNE) is currently carried out while observing the somatic motor response. This study investigated electrode placement while observing the autonomic as well as the somatic response.

METHODS

A consecutive series of ten patients (seven women) with a median age of 51.9 (range 30-75) years undergoing PNE for faecal incontinence (n = 6) and obstipation (n = 4) were investigated prospectively. Electrode placement was carried out under simultaneous electromyography (EMG) of the external anal sphincter (EAS) and internal anal sphincter (IAS) and cystomanometry.

RESULTS

PNE under control of somatic and autonomic nerve responses was carried out in all patients. In three out of ten patients, initial needle electrode placement showed single evoked EMG signals from the EAS. Final electrode placement resulted in adequate somatic motor and autonomic responses in all patients. Comparison of the increases in IAS EMG amplitude on the right and left stimulation sites for sacral nerves S3 and S4 demonstrated significant differences [S3 right: median 15.3 (interquartile range (IQR) 10.4; 20.1) µV vs. S3 left: median 11.6 (IQR 8.6; 16.0) µV, p = 0.034 and S4 right: median 24.1 (IQR 20.1; 37.2) µV vs. S4 left: median 12.0 (IQR 10.7; 13.7) µV, p = 0.012]. Stimulation-induced bladder activation was achieved in all seven patients with concomitant urinary dysfunction.

CONCLUSIONS

Control of not just the somatic motor response but also the autonomic nerve response during foramen needle electrode placement may objectify PNE.

Nerve supply to the internal anal sphincter differs from that to the distal rectum: an immunohistochemical study of cadavers

PURPOSE

Fecal incontinence is a common problem after anal sphincter-preserving operations. The intersphincteric autonomic nerves supplying the internal anal sphincter (IAS) are formed by the union of: (1) nerve fibers from Auerbach's nerve plexus of the most distal part of the rectum and (2) the inferior rectal branches of the pelvic plexus (IRB-PX) running along the conjoint longitudinal muscle coat. The aim of the present study is to identify the detailed morphology of nerves to the IAS.

METHODS

The study comprised histological and immunohistochemical evaluations of paraffin-embedded sections from a large block of anal canal from the preserved 10 cadavers.

RESULTS

The IRB-PX came from the superior aspect of the levator ani and ran into the anal canal on the anterolateral side. These nerves contained both sympathetic and parasympathetic fibers, but the sympathetic content was much higher than in nerves from the distal rectum. All intramural ganglion cells in the distal rectum were neuronal nitric oxide synthase-positive and tyrosine hydroxylase-negative and were restricted to above the squamous-columnar epithelial junction. Parasympathetic nerves formed a lattice-like plexus in the circular smooth muscles of the distal rectum, whereas the IAS contained short, longitudinally running sympathetic and parasympathetic nerves, although sympathetic nerves were dominant.

CONCLUSIONS

The major autonomic nerve input to the IAS seemed not to originate from the distal rectum but from the IRB-PX. Injury to the IRB-PX during surgery seemed to result in loss of innervation to the major part of the IAS.

Topohistology of sympathetic and parasympathetic nerve fibers in branches of the pelvic plexus: an immunohistochemical study using donated elderly cadavers

Although the pelvic autonomic plexus may be considered a mixture of sympathetic and parasympathetic nerves, little information on its composite fibers is available. Using 10 donated elderly cadavers, we investigated in detail the topohistology of nerve fibers in the posterior part of the periprostatic region in males and the infero-anterior part of the paracolpium in females. Neuronal nitric oxide synthase (nNOS) and vasoactive intestinal polypeptide (VIP) were used as parasympathetic nerve markers, and tyrosine hydroxylase (TH) was used as a marker of sympathetic nerves. In the region examined, nNOS-positive nerves (containing nNOS-positive fibers) were consistently predominant numerically. All fibers positive for these markers appeared to be thin, unmyelinated fibers. Accordingly, the pelvic plexus branches were classified into 5 types: triple-positive mixed nerves (nNOS+, VIP+, TH+, thick myelinated fibers + or -); double-positive mixed nerves (nNOS+, VIP-, TH+, thick myelinated fibers + or -); nerves in arterial walls (nNOS-, VIP+, TH+, thick myelinated fibers-); non-parasympathetic nerves (nNOS-, VIP-, TH+, thick myelinated fibers + or -); (although rare) pure sensory nerve candidates (nNOS-, VIP-, TH-, thick myelinated fibers+). Triple-positive nerves were 5-6 times more numerous in the paracolpium than in the periprostatic region. Usually, the parasympathetic nerve fibers did not occupy a specific site in a nerve, and were intermingled with sympathetic fibers. This morphology might be the result of an "incidentally" adopted nerve fiber route, rather than a target-specific pathway.

Intraoperative monitoring of bladder and internal anal sphincter innervation: a predictor of erectile function following low anterior rectal resection for rectal cancer? Results of a prospective clinical study

BACKGROUND

The objective was to investigate whether two-dimensional intraoperative neuromonitoring (IONM) of pelvic autonomic nerves has the potential to predict erectile function (EF) following surgery for rectal cancer.

METHODS

A consecutive series of 17 sexually active male rectal cancer patients undergoing IONM-based nerve-sparing low anterior rectal resection were evaluated prospectively. IONM was performed by electric stimulation of the pelvic splanchnic nerves with concomitant electromyography of the internal anal sphincter and cystomanometry. Sexual function was assessed using a validated questionnaire.

RESULTS

The degree of agreement between electromyography-based and cystomanometry-based IONM with postoperative EF was moderate and good (κ = 0.43 and κ = 0.66). Combined assessment yielded the best agreement (κ = 0.76) with sensitivity of 90%, specificity of 86%, positive predictive value of 90%, negative predictive value of 86%, and overall accuracy of 88%, respectively, in terms of prediction of postoperative EF.

CONCLUSION

The method may be suitable to predict male EF following rectal resection.

Laparoscopic neuromapping in pelvic surgery: scopes of application

BACKGROUND

New developments in intraoperative electrophysiological neuromonitoring for conventional surgery are providing further insights into functional neuroanatomy and nerve-sparing in the minor pelvis. The aim of this study was to open up potential scopes of application in laparoscopy.

METHODS

Ten patients with different indications for surgery (presacral tumor excision, n = 2; resection rectopexy. n = 2; low anterior rectal resection, n = 2; proctocolectomy. n = 2; abdomino-perineal excision of the rectum, n = 2) were investigated prospectively. The pelvic autonomic nerves were bilaterally mapped by laparoscopic electric stimulation under simultaneous electromyography of the internal anal sphincter and manometry of the bladder. Stimulation results were compared to patients' anorectal and urogenital functional outcome.

RESULTS

In all the operations laparoscopic neuromapping (LNM) was technically feasible. Laparoscopy enabled excellent visibility of pelvic neural structures for simple and differentiated electric stimulation. In all cases LNM resulted in significantly evoked electromyographic potentials and intravesical pressure rises. The technique facilitated electrophysiological determination of functional neuroanatomical topography in the minor pelvis. The stimulation results were suitable to confirm laparoscopic nerve-sparing and compatible with patients' anorectal and urogenital functional outcome.

CONCLUSIONS

LNM is technically feasible and opens up a new dimension for verification of functional nerve integrity. Further developments and investigations are mandatory to evaluate its role for laparoscopic nerve-sparing procedures.

Identification of the origin of adrenergic and cholinergic nerve fibers within the superior hypogastric plexus of the human fetus

Nerve fibers contributing to the superior hypogastric plexus (SHP) and the hypogastric nerves (HN) are currently considered to comprise an adrenergic part of the autonomic nervous system located between vertebrae (T1 and L2), with cholinergic aspects originating from the second to fourth sacral spinal segments (S2, S3 and S4). The aim of this study was to identify the origin and the nature of the nerve fibers within the SHP and the HN, especially the cholinergic fibers, using computer-assisted anatomic dissection (CAAD). Serial histological sections were performed at the level of the lumbar spine and pelvis in five human fetuses between 14 and 30 weeks of gestation. Sections were treated with histological staining [hematoxylin-eosin (HE) and Masson's trichrome (TriM)] and with immunohistochemical methods to detect nerve fibers (anti-S100), adrenergic fibers (anti-TH), cholinergic fibers (anti-VAChT) and nitrergic fibers (anti-nNOS). The sections were then digitalized using a high-resolution scanner and the 3D images were reconstructed using winsurf software. These experiments revealed the coexistence of adrenergic and cholinergic fibers within the SHP and the HNs. One-third of these cholinergic fibers were nitrergic fibers [anti-VACHT (+)/anti-NOS (+)] and potentially pro-erectile, while the others were non-nitrergic [anti-VACHT (+)/anti-NOS (-)]. We found these cholinergic fibers arose from the lumbar nerve roots. This study described the nature of the SHP nerve fibers which gives a better understanding of the urinary and sexual dysfunctions after surgical injuries.

Evaluation of two-dimensional intraoperative neuromonitoring for predicting urinary and anorectal function after rectal cancer surgery

PURPOSE

The aim of this study was to compare the results of two-dimensional intraoperative neuromonitoring (IONM) with the postoperative urinary and anorectal function of rectal cancer patients.

METHODS

A consecutive series of 35 patients undergoing low anterior resection were investigated prospectively. IONM was performed with electric stimulations of the pelvic splanchnic nerves under simultaneous manometry of the bladder and electromyography (EMG) of the internal anal sphincter (IAS). Urinary and anorectal function were evaluated preoperatively and at follow-up by standardized questionnaires, digital rectal examination scoring system, and long-term catheterization rate.

RESULTS

The rate of postoperative newly developed bladder dysfunction was 17 %. IONM with bladder manometry had a sensitivity of 100 %, specificity of 96 %, positive predictive value of 83 %, negative predictive value of 100 %, and overall accuracy of 97 %, respectively. The proportion of patients with severely impaired anorectal function at follow-up was 8 %. The sensitivity, specificity, and positive and negative predictive values for IONM with EMG of the IAS were, respectively, 100, 96, 67, and 100 % with an accuracy of 96 %. The degree of agreement for IONM with EMG of the IAS was good for anorectal function (к = 0.780) and poor for urinary function (к = 0.119). IONM with bladder manometry yielded a very good degree of agreement for urinary function (к = 0.891) and a fair agreement for anorectal function (к = 0.336).

CONCLUSIONS

The two-dimensional IONM method is suitable for verification of bladder and IAS innervation. Accurate prediction of urinary and anorectal function necessitates both bladder manometry and EMG of the IAS.

Nerves in the intersphincteric space of the human anal canal with special reference to their continuation to the enteric nerve plexus of the rectum

In the intersphincteric space of the anal canal, nerves are thought to "change" from autonomic to somatic at the level of the squamous-columnar epithelial junction of the anal canal. To compare the nerve configuration in the intersphincteric space with the configuration in adjacent areas of the human rectum, we immunohistochemically assessed tissue samples from 12 donated cadavers, using antibodies to S100, neuronal nitric oxide synthase (nNOS), and tyrosine hydroxylase (TH). Antibody to S100 revealed a clear difference in intramuscular nerve distribution patterns between the circular and longitudinal muscle layers of the most inferior part of the rectum, with the former having a plexus-like configuration, while the latter contained short, longitudinally running nerves. Most of the intramural ganglion cells in the anal canal were restricted to above the epithelial junction, but some were located just below that level. Near or at the level of the epithelial junction, the nerves along the rectal adventitia and Auerbach's nerve plexus joined to form intersphincteric nerves, with all these nerves containing both nNOS-positive parasympathetic and TH-positive sympathetic nerve fibers. Thus, it was histologically difficult to distinguish somatic intersphincteric nerves from the autonomic Auerbach's plexus. In the intersphincteric space, the autonomic nerve elements with intrapelvic courses seemed to "borrow" a nerve pathway in the peripheral branches of the pudendal nerve. Injury to the intersphincteric nerve during surgery may result in loss of innervation in the major part of the internal anal sphincter.

Resection rectopexy--laparoscopic neuromapping reveals neurogenic pathways to the lower segment of the rectum: preliminary results

PURPOSE

Nerve sparing in functional pelvic floor surgery is strongly recommended as intraoperative damage to the autonomic nerves may predispose to persistent or worsened anorectal and urogenital function. The aim of this study was to investigate the intraoperative neural topography above the pelvic floor in patients undergoing laparoscopic resection rectopexy in combination with electrophysiologic neuromapping.

METHODS

Ten consecutive female patients underwent laparoscopic resection rectopexy for rectal prolapse. Intraoperative identification of pelvic autonomic nerves was carried out with a novel intraoperative neuromonitoring system based on electric stimulation under simultaneous electromyography of the internal anal sphincter and manometry of the bladder. Neuromonitoring results were compared to patients' preoperative anorectal and urogenital function and their functional results at the 3-month follow-up.

RESULTS

Laparoscopy in combination with electrophysiologic neuromapping revealed neurogenic pathways to the lower segment of the rectum during surgical mobilization. In all procedures, intraoperative neuromonitoring finally confirmed functional nerve integrity to the internal anal sphincter and the bladder. Patients with preoperatively diagnosed fecal incontinence were continent at the 3-month follow-up. The Wexner score improved in median from preoperative 4 (range 1-18) to 1 (range 0-3) at follow-up (p = 0.012). Cleveland Clinical Constipation Score improved in median from 10 (range 5-17) to 3 (range 1-7; p = 0.005). In none of the investigated patients a new onset of urinary dysfunction did occur. No change in sexual function was observed.

CONCLUSIONS

Laparoscopy in combination with electrophysiologic neuromapping during nerve-sparing resection rectopexy identified and preserved neurogenic pathways heading to the lower segment of the rectum above the level of the pelvic floor.