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Objective To develop an ultrasound-guided technique for retrobulbar nerve block in horses, and to compare the distribution of three different volumes of injected contrast medium (CM) (4, 8 and 12 mL), with the hypothesis that successful placement of the needle within the retractor bulbi muscle cone would lead to the most effective dispersal of CM towards the nerves leaving the orbital fissure. Study design Prospective experimental cadaver study. Animals Twenty equine cadavers. Methods Ultrasound-guided retrobulbar injections were performed in 40 cadaver orbits. Ultrasound visualization of needle placement within the retractor bulbi muscle cone and spread of injected CM towards the orbital fissure were scored. Needle position and destination of CM were then assessed using computerized tomography (CT), and comparisons performed between ultrasonographic visualization of orbital structures and success rate of injections (intraconal needle placement, CM reaching the orbital fissure). Results Higher scores for ultrasound visualization resulted in a higher success rate for intraconal CM injection, as documented on the CT images. Successful intraconal placement of the needle (22/34 orbits) resulted in CM always reaching the orbital fissure. CM also reached the orbital fissure in six orbits where needle placement was extraconal. With 4, 8 and 12 mL CM, the orbital fissure was reached in 16/34, 23/34 and 28/34 injections, respectively. Conclusion and clinical relevance The present study demonstrates the use of ultrasound for visualization of anatomical structures and needle placement during retrobulbar injections in equine orbits. However, this approach needs to be repeated in controlled clinical trials to assess practicability and effectiveness in clinical practice. [ABSTRACT FROM AUTHOR]

Study Type - Therapy (case series) Level of Evidence 4 What's known on the subject? and What does the study add? Vasectomy reversal is often performed in general or neuraxial anaesthesia. Even though the site of vasectomy reversal is easily amenable to regional/local anaesthesia, spermatic cord blocks are rarely applied because of their risk of vascular damage within the spermatic cord. Recently, we described the technique of ultrasonography (US)-guided spermatic cord block for scrotal surgery, which, thanks to the US guidance, at the same time avoids the risk of vascular damage of blindly performed injections and the risks of general and neuraxial anaesthesia. Vasectomy reversal can easily be done in regional anaesthesia with the newly described technique of US-guided spermatic cord block without the risks of vascular damage by a blindly performed injection and the risks of standard general and neuraxial anaesthesia. In addition, this technique grants long-lasting postoperative pain relief and patients recover more quickly. Microsurgical conditions are excellent and patient satisfaction is high. Thanks to these advantages, more patients undergoing vasectomy reversal might avoid general or neuraxial anaesthesia. OBJECTIVE To assess the success rate, microsurgical conditions, postoperative recovery, complications and patient satisfaction of ultrasonography (US)-guided spermatic cord block in patients undergoing microscopic vasectomy reversal and to compare them to a control group with general or neuraxial anaesthesia., PATIENTS AND METHODS The present study comprised a prospective series of 10 consecutive patients undergoing US-guided spermatic cord block for microscopic vasectomy reversal., The cohort was compared with 10 patients in a historical control group with general or neuraxial anaesthesia., RESULTS Nineteen of 20 (95%) blocks were successful, defined as no pain >3 on the Visual Analogue Scale (VAS), no additional analgesics and/or no conversion to general anaesthesia. Median pain was 0 on the VAS (range 0-5). Additional analgesics were requested in one (5%) block, and there was no conversion to general anaesthesia., Microsurgical conditions were excellent., In the spermatic cord block vs general/neuraxial anaesthesia groups, median times (range) between surgery and first postoperative analgesics, alimentation, mobilization and hospital discharge were 12 (2-14) vs 3 (1-6), 1 (0.25-3) vs 4 (3-6), 2 (1-3) vs 6 (3-10), and 4 (3-11) vs 8.5 (6-22) h, respectively., No complications were reported after the spermatic cord block., Patient satisfaction was excellent., CONCLUSIONS US-guided spermatic cord block for microscopic vasectomy reversal is highly successful and provides long-lasting perioperative analgesia., Times to alimentation, mobilization and hospital discharge are shorter under US-guided spermatic cord block than under general/neuraxial anaesthesia., Additional anaesthetic pain management might, however, be required unexpectedly with US-guided spermatic cord block. [ABSTRACT FROM AUTHOR]