Work

Comparison of medial and lateral ultrasound-guided approaches to radial, ulnar, median, and musculocutaneous (RUMM) nerve injections in rats

Year: 2025

Type: article

Abstract: OBJECTIVE: To compare the length staining of the radial, ulnar, median, and musculocutaneous nerves (RUMM) in rat cadavers using one of two ultrasound-guided injection approaches: medial (MA) and lateral (LA). STUDY DESIGN: Prospective, experimental, randomized cadaveric study. ANIMALS: A group of ten frozen-thawed adult Wistar rat cadavers. METHODS: Ultrasound-guided proximal RUMM injections were performed using a volume of 0.1 mL of a bupivacaine-dye solution, divided between two injection sites: within the neurovascular sheath [radial, ulnar, and median (RUM) nerves] and near the musculocutaneous nerve. For LA (n = 10 rats, 10 limbs), a linear transducer was positioned over the triceps region at the proximal third of the brachium, oriented perpendicular to the humerus's longitudinal axis, with the needle advanced from caudal to cranial. For MA (n = 10 rats, 10 limbs), the transducer was aligned perpendicular to the proximal humeral head, with the needle introduced from caudal to cranial. Anatomical dissections were performed and length of nerve staining was measured. Data were analyzed using paired two-tailed t-tests for parametric data with significance set at p < 0.05. RESULTS: In both approaches, complete staining of RUM nerves within the neurovascular sheath was achieved. The MA resulted in significantly greater dye spread (10.4 ± 1.0 mm) than the LA (6.7 ± 1.7 mm, 95% confidence interval 2.1-5.3) (p < 0.001). All musculocutaneous nerves were stained in MA {5.0 mm [interquartile range (IQR): 4.8-6.0 mm]}, while one nerve was unstained in LA [5.5 mm (IQR: 5.0-6.0 mm)], with no observable differences between them. CONCLUSIONS AND CLINICAL RELEVANCE: The MA achieved greater dye spread length along the RUM nerves and similar spread length of the musculocutaneous nerve compared with the LA. Further studies are necessary to assess the application in live rats.

Source: Veterinary Anaesthesia and Analgesia

DOI: 10.1016/j.vaa.2025.101172

Authors: Douglas Castro, Andre Escobar, Nassim Bouhabib, Stuart C. Clark-Price, Erik H. Hofmeister

Institutions: Auburn University, Mississippi State University

Language: English

Topic: Veterinary Pharmacology and Anesthesia

Subfield: Small Animals

Field: Veterinary

Domain: Health Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $3,000