The effects of perineural and intrasynovial anaesthesia of the equine foot on subsequent magnetic resonance images.

This research investigates the potential effects of nerve and joint anesthesia on the quality of Magnetic Resonance Imaging (MRI) in equine feet. The findings suggest that such anesthesia doesn’t significantly alter MRI outcomes except for an increase in synovial fluid volume inside the digital flexor tendon sheath.

Objective of the Research

• The main aim of this research was to identify whether the process of perineural (around the nerves) and intrasynovial (inside the joints) anesthesia in equine feet could trigger any changes that would be apparent in subsequent MRIs. The researchers wondered if these procedures might affect the interpretation of MRI images.

Methods Used in the Study

• A baseline MRI of the front feet of 15 horses was conducted 2-6 days before the injection of mepivacaine (an anesthetic) around the lateral and medial palmar digital nerves and inside the podotrochlear bursa, digital flexor tendon sheath, and distal interphalangeal joint of a randomly chosen front limb.
• Additional MRIs were taken at the 24 and 72-hour marks after the injection, leading to a qualitative and quantitative appraisal of the findings.

Findings of the Study

• The MRIs captured 24 and 72 hours after the mepivacaine injection showed no substantial differences compared to the baseline when examined for the palmar digital nerves, the podotrochlear bursa, and the distal interphalangeal joint.
• However, there was a notable rise in the volume of synovial fluid within the digital flexor tendon sheath in the post-injection MRIs.

Conclusions of the Study

• According to the results, perineural anesthesia of palmar digital nerves and intrasynovial anesthesia of the podotrochlear or distal interphalangeal joint did not affect the interpretation of MRI images taken 24 or 72 hours after injection.
• Yet, the intrasynovial anesthesia of the digital flexor tendon sheath led to an iatrogenic (caused by medical examination or treatment) increase in synovial fluid that was visible in MRIs for a minimum of 72 hours post injection.
• The research concludes by suggesting that an interval of over three days should be given between the application of intrasynovial anesthesia to the digital flexor tendon sheath and conducting an MRI evaluation.