Specific Nerve Blocks

Introduction

Specfic Nerve Blocks are used when a particular region needs to be anaesthetised. It can be considered a regional block as often will block out a large region and commonly used in standing surgeries in larga animals. It is similar to infiltration methods but involves full thickness soft tissue including the nerves running through that region. Also, it can be produced by blocking the sensory nerve and nerve conduction that supplies the site.

Agents

As for infiltration, agents used include lidocaine, bupivicaine, and mepvicaine.

Uses

This procedure is commonly used in cattle when a inverted L block is performed when a caesarean section is required. Other types include ring blocks, which are commonly used when an extremity is being blocked such as a distal limb or tail etc. It is important to test the area before any procedure is performed to ensure the agent has had enough time to act, and the appropriate area has been blocked. It can also be used in diagnostic procedures such as lameness investigations.

Commonly used blocks include: -

• Inverted L Block
• Ring blocks
• Distal limb blocks including palmer digital, abaxial sesamoid and low 4 point for example.
• Cornual nerve block.

Advantages

• Removes the need for sedation for some patients.
• Relatively easy to perform.
• Requires basic equipment - Hypodermic needle and syringe.

Disadvantages

• Agents cannot pass over fascial sheet so if nerve is seperated by fascia then it may not be blocked.
• Requires thorough knowledge of topographical anatomy of nerves.