Retromuscular drain output at removal does not influence adverse outcome rate in open ventral hernia repairs.

BACKGROUND: Retromuscular drains are commonly placed during retromuscular hernia repair (RHR) to decrease postoperative wound complications and help mesh in-growth. Drains are traditionally removed when output is low but the relationship between drain output at the time of removal and postoperative complications has yet to be delineated. This study aimed to investigate outcomes of RHR patients with drain removal at either high or low output volume. METHODS: An institutional review board-approved retrospective chart review evaluated adult patients undergoing open RHR with retromuscular drain placement between 2013 and 2022 at a single academic medical center. Patients were stratified into low output drainage (LOD, < 50 mL/day) or high output drainage (HOD, ≥ 50 mL/day) groups based on volume on the day of drain removal. RESULTS: We identified 336 patients meeting inclusion criteria: 58% LOD (n = 195) and 42% HOD (n = 141). Demographics and risk factors pertaining to hernia complexity were similar between cohorts. Low-drain output at the time of removal was associated with a significantly longer drain duration (6.3 ± 4.5 vs. 4.4 ± 1.6 days, p < 0.001) and postoperative hospital stay (5.9 ± 3.6 vs. 4.8 ± 2.8 days, p < 0.001). With a 97% 30-day follow-up, incidence of surgical site occurrence (SSO) was not statistically different between groups (29.2% LOD, 26.2% HOD, p = 0.63). Surgical site infection and SSO requiring procedural intervention was also not statistically significant between cohort. At 1-year follow-up, hernia recurrence rates were the same between groups (4.2% LOD, 1.4% HOD, p = 0.25). CONCLUSION: Following open ventral hernia repair with retromuscular mesh placement, the rate of postoperative wound complications was not statistically different based on volume of drain output day of removal. These results suggest that removing drains earlier despite higher output is safe and has no effect on short- or long-term hernia outcomes.

Updated guideline for closure of abdominal wall incisions from the European and American Hernia Societies.

BACKGROUND: Incisional hernia is a frequent complication of abdominal wall incision. Surgical technique is an important risk factor for the development of incisional hernia. The aim of these updated guidelines was to provide recommendations to decrease the incidence of incisional hernia. METHODS: A systematic literature search of MEDLINE, Embase, and Cochrane CENTRAL was performed on 22 January 2022. The Scottish Intercollegiate Guidelines Network instrument was used to evaluate systematic reviews and meta-analyses, RCTs, and cohort studies. The GRADE approach (Grading of Recommendations, Assessment, Development and Evaluation) was used to appraise the certainty of the evidence. The guidelines group consisted of surgical specialists, a biomedical information specialist, certified guideline methodologist, and patient representative. RESULTS: Thirty-nine papers were included covering seven key questions, and weak recommendations were made for all of these. Laparoscopic surgery and non-midline incisions are suggested to be preferred when safe and feasible. In laparoscopic surgery, suturing the fascial defect of trocar sites of 10 mm and larger is advised, especially after single-incision laparoscopic surgery and at the umbilicus. For closure of an elective midline laparotomy, a continuous small-bites suturing technique with a slowly absorbable suture is suggested. Prophylactic mesh augmentation after elective midline laparotomy can be considered to reduce the risk of incisional hernia; a permanent synthetic mesh in either the onlay or retromuscular position is advised. CONCLUSION: These updated guidelines may help surgeons in selecting the optimal approach and location of abdominal wall incisions.

An incisional hernia results from a weakness of the abdominal wall muscles that allows fat from the inside or organs to bulge out. These hernias are quite common after abdominal surgery at the site of a previous incision. There is research that discusses different ways to close an incision and this may relate to the chance of hernia formation. The aim of this study was to review the latest research and to provide a guide for surgeons on how best to close incisions to decrease hernia rates. When possible, surgery through small incisions may decrease the risk of hernia formation. If small incisions are used, it may be better if they are placed away from areas that are already weak (such as the belly button). If the incision is larger than 1 cm, it should be closed with a deep muscle-fascia suture in addition to skin sutures. If there is a large incision in the middle of the abdomen, the muscle should be sutured using small stitches that are close together and a slowly absorbable suture should be used. For patients who are at higher risk of developing hernias, when closing the incision, the muscle layer can be strengthened by using a piece of (synthetic) mesh. There is no good research available on recovery after surgery and no clear guides on activity level or whether a binder will help prevent hernia formation.

Registry-Based Trainee Assessments: Leveraging a Quality Collaborative for Surgical Education.

INTRODUCTION: We present our experience developing and embedding a registry-based module for resident feedback. METHODS: At our institution, entering operative data into the institutional quality collaborative registry is standard practice. In February 2019, a surgical education module was embedded into the registry to capture procedure-specific resident operative assessments. Faculty engagement with the sugical education module was assessed during its first year in existence (February 2019-February 2020). RESULTS: In total, 1074 of 1269 (85%) operative assessments were completed by 27 faculty via the surgical education registry module. Median faculty engagement rate with the module following resident-assisted procedures was 91% [IQR 76%-100%]. Residents received a median of 7 operative assessments [IQR 2-19] over the study period. CONCLUSION: By embedding a surgical education module into an existing surgical quality collaborative registry, procedure-specific operative assessments can be routinely captured.

Multidisciplinary Simulation Training Improves Surgical Resident Comfort With Airway Management.

BACKGROUND: Airway management is an essential element of surgical training, but with fewer procedures performed during residency, simulation is crucial to fill educational gaps. We evaluated the effect of a multidisciplinary airway simulation on the comfort of general surgery residents in managing airways. MATERIALS AND METHODS: All residents PGY 2-5 at a large academic general surgery residency program participated in a multidisciplinary airway management simulation. Precourse surveys evaluated self-perception of skills in three areas of airway management: surgical airway, basic ventilator strategies, and endotracheal intubation. Simulation consisted of didactic and procedural components and used high- and low-fidelity models including silicon airways, ventilators, porcine trachea, and airway adjuncts. Instruction was provided by anesthesia and otolaryngology faculty. Postcourse assessment was performed with a four-level Likert questionnaire. Results were analyzed using paired t-tests. RESULTS: Of the 19 residents surveyed, 37% of residents had 1-5 h and 32% had 5-10 h of prior airway instruction. Significant increases in mean comfort were observed across all three studied areas. Residents reported increased comfort performing a surgical airway (1.16 versus 1.95), P < 0.0001, and troubleshooting ventilator issues (1.59 versus 2.16), P < 0.0001. Comfort regarding overall airway management including endotracheal intubation demonstrated similar improvement (1.84 versus 2.32), P = 0.02. Subgroup analysis by PGY level showed the greatest impact on comfort level in junior residents. CONCLUSIONS: Multidisciplinary airway simulation can be effectively implemented in a general surgery training program and positively affect trainee comfort with these techniques, particularly among junior residents.

Registry-Based Randomized Controlled Trials: A New Paradigm for Surgical Research.

BACKGROUND: Randomized controlled trials (RCTs) are the gold standard to establish evidence for surgical practice but can be hindered by high costs, complexity, and time requirements. Recently, observational registries have been leveraged as platforms for clinical trials to address these limitations, though few registry-based surgical RCTs have been conducted. Here, we present our group's approach to surgical registry-based RCTs and early results. MATERIALS AND METHODS: To facilitate these trials, we focused on registry integration into surgeons' workflows, routine collection of patient-reported outcomes at clinic visits, and pragmatic trial design featuring broad inclusion criteria and standard of care follow-up. These features maximize generalizability and facilitate follow-up by minimizing visits and tests outside of normal practice. RESULTS: Since 2017, our group has completed enrollment in 4 registry-based RCTs with another 5 trials ongoing. Of these, 4 trials have been multicenter. Over 1000 patients have been enrolled in these studies, with follow-up rates of 90% or greater. Most of these trials are on track to complete enrollment in approximately 2 y from their start date. Beyond salary support, resource utilization is low. None of our trials has been terminated due to lack of resources or futility. CONCLUSIONS: Registry-based RCTs allow for efficient conduct of pragmatic surgical trials. Thoughtful study design, registry integration into surgeons' routines, and a team culture embracing research are paramount. We believe registry-based trials are the future of affordable, high-level, prospective surgical research.

Late chronotype is associated with enhanced amygdala reactivity and reduced fronto-limbic functional connectivity to fearful versus happy facial expressions.

Increasing evidence suggests late chronotype individuals are at increased risk of developing depression. However, the underlying neural mechanisms that confer risk are not fully understood. Here, fifty healthy, right-handed individuals without a current or previous diagnosis of depression, family history of depression or sleep disorder underwent functional magnetic resonance imaging (FMRI). Participants completed an implicit emotion processing task (gender discrimination) including happy and fearful facial expressions. Linear effects of chronotype on BOLD response in bilateral amygdala were tested for significance using nonparametric permutation tests. Functional connectivity between amygdala and prefrontal cortex was also investigated using psychophysiological interaction (PPI) analysis. A significant negative correlation between BOLD response and chronotype was observed in bilateral amygdala where later chronotype was associated with an enhanced amygdala response to fearful vs. happy faces. This response remained significant after sleep quality, age, gender, mood, and time of scan were included as covariates in the regression model. Later chronotype was also significantly associated with reduced functional connectivity between amygdala and dorsal anterior cingulate cortex (dACC). The current results appear consistent with theories of impaired emotion regulation of the limbic system (particularly the amygdala) associated with depression and may, in part, explain the increased vulnerability for depression in late chronotype individuals.

Reducing the incidence of surgical site infection after ventral hernia repair: Outcomes from the RINSE randomized control trial.

BACKGROUND: The clinical and financial impact of surgical site infection after ventral hernia repair is significant. Here we investigate the impact of dual antibiotic irrigation on SSI after VHR. METHODS: This was a multicenter, prospective randomized control trial of open retromuscular VHR with mesh. Patients were randomized to gentamicin â€‹+ â€‹clindamycin (G â€‹+ â€‹C) (n â€‹= â€‹125) vs saline (n â€‹= â€‹125) irrigation at time of mesh placement. Primary outcome was 30-day SSI. RESULTS: No significant difference was seen in SSI between control and antibiotic irrigation (9.91 vs 9.09 â€‹%; p â€‹= â€‹0.836). No differences were seen in secondary outcomes: SSO (11.71 vs 13.64 â€‹%; p â€‹= â€‹0.667); 90-day SSO (11.1 vs 13.9 â€‹%; p â€‹= â€‹0.603); 90-day SSI (6.9 vs 3.8 â€‹%; p â€‹= â€‹0.389); SSIPI (7.21 vs 7.27 â€‹%, p â€‹= â€‹0.985); SSOPI (3.6 vs 3.64 â€‹%; p â€‹= â€‹0.990); 30-day readmission (9.91 vs 6.36 â€‹%; p â€‹= â€‹0.335); reoperation (5.41 vs 0.91 â€‹%; p â€‹= â€‹0.056). CONCLUSION: Dual antibiotic irrigation with G â€‹+ â€‹C did not reduce the risk of surgical site infection during open retromuscular ventral hernia repair.

Psychotic Like Experiences in Healthy Adolescents are Underpinned by Lower Fronto-Temporal Cortical Gyrification: a Study from the IMAGEN Consortium.

BACKGROUND AND HYPOTHESIS: Psychotic Like Experiences (PLEs) are widely prevalent in children and adolescents and increase the risk of developing psychosis. Cortical gyrification characterizes brain development from in utero till about the first 2 years of life and can be measured in later years as static gyrification changes demonstrating neurodevelopment and dynamic gyrification changes reflecting brain maturation during adolescence. We hypothesized that PLEs would be associated with static cortical gyrification changes reflecting a neurodevelopmental abnormality. STUDY DESIGN: We studied 1252 adolescents recruited in the IMAGEN consortium. We used a longitudinal study design, with Magnetic Resonance Imaging measurements at age 14 years and age 19 years; measurement of PLEs using the Community Assessment of Psychic Experiences (CAPE) questionnaire at age 19 years; and clinical diagnoses at age 23 years. STUDY RESULTS: Our results show static gyrification changes in adolescents with elevated PLEs on 3 items of the CAPE-voice hearing, unusual experiences of receiving messages, and persecutory ideas-with lower cortical gyrification in fronto-temporal regions in the left hemisphere. This group also demonstrated dynamic gyrification changes with higher cortical gyrification in right parietal cortex in late adolescence; a finding that we replicated in an independent sample of patients with first-episode psychosis. Adolescents with high PLEs were also 5.6 times more likely to transition to psychosis in adulthood by age 23 years. CONCLUSIONS: This is the largest study in adolescents that demonstrates fronto-temporal abnormality of cortical gyrification as a potential biomarker for vulnerability to PLEs and transition to psychosis.

Radiographic identification of thoracoabdominal hernias.

PURPOSE: Hernias spanning both chest and abdominal walls are uncommon and associated with chest wall trauma, coughing and obesity. This study describes the radiographic appearance of these hernias to guide proper identification and operative planning. Proposed standardized reporting patterns are also presented. METHODS: The cross sectional imaging of patients presenting with thoracoabdominal hernias was reviewed. Radiographic reports were supplemented by surgeon imaging review and operative findings during repair. Defect dimensions, hernia content, level of herniation, presence of osseous or cartilaginous disruption of the chest wall and degree of rib displacement were collected. Disruption of myofascial planes was also noted. RESULTS: Six patients were identified. All hernias occurred below the 9th rib and were associated with complete intercostal muscle disruption. The transversus abdominis was disrupted in all hernias and the internal oblique was disrupted in five of the hernias. The majority (83%) had caudal rib displacement (median 6.8 cm compared to contralateral side). Median hernia width was 10.35 cm (1.6-19.1 cm) and median length was 10.2 cm (1.8-14.3 cm). Five patients had associated bone/cartilage injuries: two with 11th rib fractures, two with combined bone and cartilaginous fractures and one with a surgical rib resection. CONCLUSION: The typical injury pattern of thoracoabdominal hernias includes disruption of the intercostal muscles, transversus abdominis, and commonly the internal oblique with an intact external oblique. Inferior rib displacement by hernia contents and unopposed pull of the abdominal musculature is common. Osseous or cartilaginous disruption always occurs unless the defect is bounded on at least one side by a floating rib.

The role of cognitive control in the positive symptoms of psychosis.

BACKGROUND: Positive symptoms of psychosis (e.g., hallucinations) often limit everyday functioning and can persist despite adequate antipsychotic treatment. We investigated whether poor cognitive control is a mechanism underlying these symptoms. METHODS: 97 patients with early psychosis (30 with high positive symptoms (HS) and 67 with low positive symptoms (LS)) and 40 healthy controls (HC) underwent fMRI whilst performing a reward learning task with two conditions; low cognitive demand (choosing between neutral faces) and high cognitive demand (choosing between angry and happy faces - shown to induce an emotional bias). Decision and feedback phases were examined. RESULTS: Both patient groups showed suboptimal learning behaviour compared to HC and altered activity within a core reward network including occipital/lingual gyrus (decision), rostral Anterior Cingulate Cortex, left pre-central gyrus and Supplementary Motor Cortex (feedback). In the low cognitive demand condition, HS group showed significantly reduced activity in Supplementary Motor Area (SMA)/pre-SMA during the decision phase whilst activity was increased in LS group compared to HC. Recruitment of this region suggests a top-down compensatory mechanism important for control of positive symptoms. With additional cognitive demand (emotional vs. neutral contrast), HS patients showed further alterations within a subcortical network (increased left amygdala activity during decisions and reduced left pallidum and thalamus activity during feedback) compared to LS patients. CONCLUSIONS: The findings suggest a core reward system deficit may be present in both patient groups, but persistent positive symptoms are associated with a specific dysfunction within a network needed to integrate social-emotional information with reward feedback.

Cognitive control network connectivity differentially disrupted in treatment resistant schizophrenia.

Antipsychotic treatment resistance affects a third of people with schizophrenia and the underlying mechanism remains unclear. We used an fMRI emotion-yoked reward learning task, allied to prefrontal cortical glutamate levels, to explain the role of cognitive control in differentiating treatment-resistant from responsive patients. We investigated how reward learning is disrupted at the network level in 21 medicated treatment-responsive and 20 medicated treatment-resistant patients with schizophrenia compared with 24 healthy controls (HC). Dynamic Causal Modelling assessed how effective connectivity between regions in a cortico-striatal-limbic network is disrupted in each patient group compared to HC. Connectivity was also examined with respect to symptoms, salience and anterior cingulate (ACC) glutamate levels measured from the same region of the ACC. We found that ACC connectivity differentiated these patient groups, with responsive patients exhibiting increased top-down connectivity from ACC to sensory regions and reduced ACC drive to the striatum, while resistant patients showed altered connectivity within the ACC itself. In these resistant patients, the ACC drive to striatum was positively correlated with their symptom severity. ACC glutamate levels were found to correlate with ACC control over sensory regions in responsive patients but not in resistant patients. We suggest a central non-dopaminergic impairment that impacts cognitive control networks in treatment-resistant schizophrenia. This impairment was associated with disrupted reward learning and could be underpinned by aberrant glutamate function. These findings should form the focus of future treatment strategies (e.g. glutamatergic targets and giving clozapine earlier) in resistant patients.

Patient-reported opioid use after open abdominal wall reconstruction: How low can we go?

BACKGROUND: Little data exist to inform discharge opioid prescribing for patients undergoing abdominal wall reconstruction. The aim of this study was to evaluate postoperative, patient-reported opioid use after abdominal wall reconstruction. We hypothesized that the majority of patients undergoing open abdominal wall reconstruction would require between 16 and 30 opioid tablets after discharge. METHODS: Postoperative, patient-reported opioid use was collected prospectively for all patients undergoing elective, open abdominal wall reconstruction at a single high-volume center. All opioid medications were converted to an equivalent number of 5 mg oxycodone tablets. The primary outcome was the total number of opioid tablets taken within 30 days of hospital discharge after abdominal wall reconstruction. RESULTS: Ninety-eight patients were included. Median hernia width was 15 cm (interquartile range 12-19), 42% were recurrences, and all underwent transversus abdominis release. At the 30-day follow-up visit, 24% reported no postdischarge opioid use, and 76% reported taking 15 tablets or fewer. Of the 23 patients who used no opioids on the day before discharge, 16 (70%) reported taking no opioids after discharge. CONCLUSION: Most patients reported taking fewer opioid tablets than prescribed and fewer than our hypothesis within 30 days of abdominal wall reconstruction. Opioid use on the day before discharge may allow for prognostication of outpatient opioid requirements to prevent overprescribing.

Functional magnetic resonance spectroscopy in patients with schizophrenia and bipolar affective disorder: Glutamate dynamics in the anterior cingulate cortex during a working memory task.

The glutamate system is implicated in the pathophysiology of schizophrenia and mood disorders. Using functional magnetic resonance spectroscopy (1H-fMRS), it is possible to monitor glutamate dynamically in activated brain areas and may give a closer estimate of glutamatergic neurotransmission than standard magnetic resonance spectroscopy. 14 patients with schizophrenia, 15 patients with bipolar disorder II (BPII) and 14 healthy volunteers underwent a 15 min N-back task in a 48s block design during 1H-fMRS acquisition. Data from the first, second and third 16s group of 8 spectra for each block were analysed to measure levels of glutamate and Glx (glutamate + glutamine), scaled to total creatine (TCr), across averaged 0-back and 2-back conditions. A 6 × 3 repeated-measures analysis of variance (rmANOVA) demonstrated a significant main effect of time for Glx/TCr (P = 0.022). There was a significant increase in Glu/TCr (P = 0.004) and Glx/TCr (P < 0.001) between the final spectra of the 0-back and first spectra of the 2-back condition in the healthy control group only. 2 × 2 rmANOVA revealed a significant time by group interaction for Glx/TCr (P = 0.019) across the 0-back condition, with levels reducing in healthy controls and increasing in the schizophrenia group. While healthy volunteers showed significant increases in glutamatergic measures between task conditions, the lack of such a response in patients with schizophrenia and BPII may reflect deficits in glutamatergic neurotransmission. Abnormal increases during periods of relatively low executive load, without the same dynamic modulation as healthy volunteers with increasing task difficulty, further suggests underlying abnormalities of glutamatergic neurotransmission in schizophrenia.

Inflammation, Glutamate, and Cognition in Bipolar Disorder Type II: A Proof of Concept Study.

Background: Two current theories regarding the neuroscientific bases of mood disorders involve alterations in glutamatergic neurotransmission and excessive activation of inflammatory pathways. We hypothesized that glutamate (Glu) levels and peripheral inflammatory markers would be associated with cognitive function, in patients with Bipolar Disorder Type II (BP-II), and that such factors would be associated with psychological treatment outcomes. Aims: The primary aim of this study was to explore the relationship between the neurotransmitter Glu, cytokines (CRP, IL_6, and TNFa) and neuropsychological and related functioning. The secondary aim was to assess cognitive functioning as a predictor of poor response to psychological therapy. Methods: Proton magnetic resonance spectroscopy data were acquired from the anterior cingulate cortex (ACC) of 15 participants with BP-II, and 13 healthy controls in a 3T magnetic resonance imaging scanner. The Digit Symbol Task (DST) for processing speed, TMT-B for executive function and Rey Auditory Verbal Learning Test (RAVLT) were administered to assess cognitive domains. Results: There was no significant difference in anterior cingulate Glu, or inflammatory markers between groups. Furthermore, we found no significant difference between groups in any cognitive tests. Scores on the DST were found to be significantly associated with poor response to psychological therapy. Conclusions: This study may highlight an association between neuropsychological dysfunction and treatment outcome in euthymic patients with BP-II. We did not find any association between peripheral inflammatory markers and brain Glu levels. This may have been in part due to the small sample size.

Mapping cortical surface features in treatment resistant schizophrenia with in vivo structural MRI.

Decreases in cortical volume (CV), thickness (CT) and surface area (SA) have been reported in individuals with schizophrenia by in vivo MRI studies. However, there are few studies that examine these cortical measures as potential biomarkers of treatment resistance (TR) and treatment response (NTR) in schizophrenia. This study used structural MRI to examine differences in CV, CT, and SA in 42 adults with schizophrenia (TR = 21, NTR = 21) and 23 healthy controls (HC) to test the hypothesis that individuals with TR schizophrenia have significantly greater reductions in these cortical measures compared to individuals with NTR schizophrenia. We found that individuals with TR schizophrenia showed significant reductions in CV and CT compared to individuals with NTR schizophrenia in right frontal and precentral regions, right parietal and occipital cortex, left temporal cortex and bilateral cingulate cortex. In line with previous literature, the temporal lobe and cingulate gyrus in both patient groups showed significant reductions of all three measures when compared to healthy controls. Taken together these results suggest that regional changes in CV and CT may index mechanisms specific to TR schizophrenia and potentially identify patients with TR schizophrenia for earlier treatment.

Exploring the effect of chronotype on hippocampal volume and shape: A combined approach.

Current evidence suggests that acute depression is associated with reduced total hippocampal volume and regional atrophy. Here, using structural magnetic resonance imaging, we assayed linear effects of chronotype on total hippocampal volume and morphology. Later chronotype was associated with localised atrophy in the subiculum region of the right hippocampus in the absence of changes in total volume. The hippocampus forms a key node in a network of brain regions implicated in emotional regulation and alterations in the structure of this region may underpin, in part, the increased vulnerability for depression in late chronotype individuals.

Altered resting-state connectivity within default mode network associated with late chronotype.

Current evidence suggests late chronotype individuals have an increased risk of developing depression. However, the underlying neural mechanisms of this association are not fully understood. Forty-six healthy, right-handed individuals free of current or previous diagnosis of depression, family history of depression or sleep disorder underwent resting-state functional Magnetic Resonance Imaging (rsFMRI). Using an Independent Component Analysis (ICA) approach, the Default Mode Network (DMN) was identified based on a well validated template. Linear effects of chronotype on DMN connectivity were tested for significance using non-parametric permutation tests (applying 5000 permutations). Sleep quality, age, gender, measures of mood and anxiety, time of scan and cortical grey matter volume were included as covariates in the regression model. A significant positive correlation between chronotype and functional connectivity within nodes of the DMN was observed, including; bilateral PCC and precuneus, such that later chronotype (participants with lower rMEQ scores) was associated with decreased connectivity within these regions. The current results appear consistent with altered DMN connectivity in depressed patients and weighted evidence towards reduced DMN connectivity in other at-risk populations which may, in part, explain the increased vulnerability for depression in late chronotype individuals. The effect may be driven by self-critical thoughts associated with late chronotype although future studies are needed to directly investigate this.

Minimally Invasive Approaches to Inguinal Hernias.

Both the transabdominal preperitoneal approach and the total extraperitoneal approach to inguinal hernias provide an effective means of repairing inguinal hernias. The robotic platform can be used and may help to decrease immediate postoperative pain; however, as this is a fairly new technique, more research will help further determine long-term outcomes. In all methods of fixation, we ensure adequate fixation medially with tacks placed on the Cooper ligament. Awareness of the nerves and vessels helps to guide dissection as well as prevent inadvertent injury during mesh fixation.