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Abstract 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.

Abstract It has been found that rectal surgery still leads to high rates of postoperative urinary, fecal, or sexual dysfunction, which is why nerve-sparing surgery has gained increasing importance. To improve functional outcomes, techniques to preserve pelvic autonomic nerves by identifying anatomic landmarks and implementing intraoperative neuromonitoring methods have been investigated. The objective of this study was to transfer a new approach to intraoperative pelvic neuromonitoring based on bioimpedance measurement to a clinical setting. Thirty patients (16 male, 14 female) involved in a prospective clinical investigation (German Clinical Trials Register DRKS00017437, date of first registration 31/03/2020) underwent nerve-sparing rectal surgery using a new approach to intraoperative pelvic neuromonitoring based on direct nerve stimulation and impedance measurement on target organs. Clinical feasibility of the method was outlined in 93.3% of the cases. Smooth muscle contraction of the urinary bladder and/ or the rectum in response to direct stimulation of innervating functional nerves correlated with a change in tissue impedance compared with the pre-contraction state. The mean amplitude (Amax) of positive signal responses was Amax = 3.8%, negative signal responses from a control tissue portion with no stimulation-induced impedance change had an amplitude variation of 0.4% on average. The amplitudes of positive and negative signal responses differed significantly (statistical analysis using two-sided t-test), allowing the nerves to be identified and preserved. The results indicate a reliable identification of pelvic autonomic nerves during rectal surgery.

Abstract Low anterior resections (LAR) are frequently associated with complications such as urinary and fecal incontinence as well as sexual disorders. Typical risk factors are rectal cancer with low tumor location, preoperative radiotherapy, and surgery-related damage of pelvic autonomic nerves. As preserving the pelvic autonomic nerves without any technical assistance is challenging, the objective of this preclinical study was to investigate the technical feasibility of a new method for intraoperative pelvic neuromonitoring. Twelve female pigs undergoing low anterior resections were involved in a prospective preclinical study. Intraoperative pelvic neuromonitoring included direct pelvic nerve stimulation and tissue impedance measurement on the urinary bladder and the rectum for the identification of efferent pelvic nerves in the surgical area. Immunohistochemistry was used to verify the results. Smooth muscle contraction of the urinary bladder and/or the rectum in response to direct stimulation of the innervating nerves was detectable with impedance measurement. The macroscopic contraction of both the urinary bladder and the rectum correlated with a change in tissue impedance compared to the status before contraction. Thus, it was possible to identify pelvic nerves in the surgical area, which allows the nerves to be preserved. The results indicate a reliable identification of pelvic autonomic nerves, which allows nerve damage to be prevented in the future.

Abstract Painful lesions on the plantar aspect of the first interphalangeal joint (IPJ) of the hallux can be attributed to structures called ossicles, nodules, or sesamoids. The aims of the present study were first to verify that ultrasonography (US) is a high-sensitivity tool for diagnosing an interphalangeal ossicle (IO), and second to prove that US-guided-shaving surgery (“milling”) is a safe and feasible technique for remodeling the IO. The study is divided into three parts. In the first part, the prevalence of IOs was estimated in 12 cadaver feet using US, anatomical dissection, and fluoroscopy. In the second, a detailed US and morphological description of the IO was obtained. In the third, six cadaver feet were subjected to surgical milling. IO prevalence was 41.6% in gross anatomy, 41.6% in US examination and just 16.6% in fluoroscopy. The ossicles had a mean length of 4 mm (± 2 mm) and a width of 7 mm (± 2 mm). The ossicles could be completely shaved in all specimens without injuring important anatomical structures. Our results indicate that US is a more precise tool for diagnosing an IO than X-ray. Moreover, our US-guided mini-invasive surgical technique appears feasible and safe.