Ultrasound-guided blockade of the dorsal nerve of the penis in a Great Dane

This report describes an approach to regional anaesthesia of the dorsal nerves of the penis in a Great Dane, as part of an anaesthetic protocol for surgical urethral resection and anastomosis. Bupivacaine (0.5%) was infiltrated around the left and right dorsal nerves of the penis, with ultrasound guidance. The locoregional approach was trans-perineal, with the ultrasound probe orientated at a right angle to the anus, at the level of the ischial symphysis. The described technique provided good visualisation of the urethra and dorsal arteries of the penis. No adverse events relating to the nerve blockade were encountered and no additional analgesia, other than the methadone premedication, was required intra-operatively. The locoregional approach was subsequently repeated on a cadaver using the same technique and, on dissection, demonstrated deposition of injectate next to the target neurovascular bundles. The technique described may provide a simple method of distal penile anaesthesia in the dog, where ultrasound is available.

A neuromonitoring framework supporting the intraoperative placement of an epidural spinal cord electrode array for functional restoration in people with paraplegia

Targeted stimulation of dorsal nerve roots of the lumbosacral spinal cord (SC) represents a promising way to improve lower extremity functions for people with paraplegia due to SC injury. Stimulation pulses are selectively applied at different segments of the SC by means of an implanted electrode array. For an optimal clinical outcome, correct positioning of the array in rostrocaudal and mediolateral direction of the SC is essential. We developed a neuromonitoring framework to support the neurosurgeon during the implantation procedure by automated stimulation and real-time analysis of evoked muscular responses. For the implementation we developed and combined a new software with several hardware and software modules for intraoperative neuromonitoring. The new software coordinates different interfaces and components including a neurostimulator, a multiplexer module and a biosignal amplifier. In addition, a graphical user interface (GUI) was implemented, allowing control of the system and display of analyzed data. With the framework, stimulation sequences in respect to stimulation amplitudes and selection of contacts of the electrode array can be predefined and executed in an automated manner. Synchronously the evoked electromyographic responses of the target muscles can be recorded, analyzed and displayed together with the stimulation setup for visual evaluation. The framework serves as a fundamental basis for the integration of a clinical knowledge-based algorithm and the realization of a future neuromonitoring system for this purpose.

Time course for urethral neuromuscular reestablishment and its facilitated recovery by transcutaneous neuromodulation after simulated birth trauma in rats

The aims of the study were to determine the time-course of urinary incontinence recovery after vaginal distension (VD), elucidate the mechanisms of injury from VD leading to external urethral sphincter (EUS) dysfunction, and assess if transcutaneous electrical stimulation (TENS) of the dorsal nerve of the clitoris facilitates recovery of urinary continence after VD. Rats underwent 4-h VD, 4-h sham VD (SH-VD), VD plus 1-h DNC TENS, and VD plus 1-h sham TENS (SH-TENS). TENS or SH-TENS were applied immediately and at days 2 and 4 post-VD. Micturition behavior, urethral histochemistry and histology, EUS and nerve electrophysiology, and cystometrograms were evaluated. VD induced urine leakage and disrupted EUS fibers and nerve-conduction. Urine leakage disappeared 13 days post-VD. Structural and functional recovery of the EUS neuromuscular circuitry started by day 6 post-VD but did not fully recovered by day 11 post-VD. TENS significantly decreased the frequency of urine leakage post-VD (p<0.01). We conclude that rat urinary continence function after VD requires 2 weeks to recover, although urethra structure is not fully recovered. Treatment to facilitate neuroregeneration should be applied within one-week after damage. TENS facilitated urinary continence recovery after VD. This treatment may have potential to decrease postpartum urinary incontinence in women.

The Degenerate Tale of Ascidian Tails

Ascidians are invertebrate chordates, with swimming chordate tadpole larvae that have distinct heads and tails. The head contains the small brain, sensory organs, including the ocellus (light) and otolith (gravity) and the presumptive endoderm, while the tail has a notochord surrounded by muscle cells and a dorsal nerve cord. One of the chordate features is a post-anal tail. Ascidian tadpoles are nonfeeding, but their tail is critical for larval locomotion. After hatching the larvae swim up towards light and are carried by the tide and ocean currents. When competent to settle, ascidian tadpole larvae swim down, away from light, to settle and metamorphose into a sessile adult. Tunicates are classified as chordates because of their chordate tadpole larvae; in contrast, the sessile adult has a U-shaped gut and very derived body plan, looking nothing like a chordate. There is one group of ascidians, the Molgulidae, where many species are known to have tailless larvae. The Swalla Lab has been studying the evolution of tailless ascidian larvae in this clade for over thirty years and has shown that tailless larvae have evolved independently several times in this clade. Comparison of the genomes of two closely related species, the tailed Molgula oculata and tailless Molgula occulta reveals much synteny, but there have been multiple insertions and deletions that have disrupted larval genes in the tailless species. Genomics and transcriptomics have previously shown that there are expressed pseudogenes in the tailless embryos, suggesting that the partial rescue of tailed features in their hybrid larvae is due to the expression of intact genes from the tailed parent. Yet surprisingly, we find that the notochord gene regulatory network is mostly intact in the tailless M. occulta, although the notochord does not converge and extend and remains as an aggregate of cells we call the “notoball”. We expect that eventually many of the larval gene networks will be become evolutionarily lost in tailless ascidians and the larval body plan abandoned, with eggs developing directly into an adult. Here we review the current evolutionary and developmental evidence on how the molgulids lost their tails.