equis - Articles
Hindlimb: perineural analgesia
Synonym(s): Nerve block
Introduction
- By removing sensitization to source of pain, lameness is abolished or lessened.
- Technique is conducted sequentially working from distal to proximal.
Uses
- Valuable diagnostic tool for localization of pain causing lameness or poor performance.
- Direct diagnostic imaging, diagnosis and prognosis.
- Peri-operative analgesia.
Advantages
- Systematic procedure.
- Minimally invasive.
- Good regional localization of source(s) of pain is a valuable adjunct to lameness or poor performance work-ups.
- Majority of perineural analgesia techniques are easy to perform.
Disadvantages
- Local anesthetic solution may diffuse from deposition site and desensitize adjacent structures (eg joints, bursae, tendon sheaths) or more proximal nerves. Perineural analgesia is not as specific as once thought,
- Accurate technique and choice of volume of local anesthetic solution are essential
- Careful interpretation of results often requires experience
- Can be time consuming if multiple blocks are to be performed in multiple limbs.
- Anesthetic solution irritates tissues and can cause low grade inflammation → may sometimes confound scintigraphic imaging techniques for up to 2 weeks.
- Procedure complicated by fractious horses.
- There is a risk of introducing bacteria, and therefore infection.
Technical problems
- Good anatomical knowledge essential.
- Desensitization may not occur in the desired or intended regions.
- Inadvertent administration of local anesthetic solution into a synovial structure or blood vessel → misinterpretation of results and sterility concerns.
- Full (100%) resolution of lameness is ideal, however this is not always achieved and an improvement of 70-80% is generally considered a positive response.
- Diagnostic analgesia will not improve lameness associated with mechanical gait deficits.
- In horse with multi-limb lameness, all blocks should be performed before the first positive block wears off (90-120 min for mepivacaine Mepivacaine).
Alternative techniques
- Gait evaluation Musculoskeletal: gait evaluation.
- Examination of horse at rest Musculoskeletal: physical examination - adult, including thorough hoof and foot examination.
- Manipulative tests Musculoskeletal: manipulative tests.
- Intrasynovial anesthesia Hindlimb: joint anesthesia.
- Radiography Hindlimb: radiography.
- Ultrasonography Ultrasonography: musculoskeletal.
- Scintigraphy Bone: scintigraphy.
- Thermography Thermography.
- Computed tomography (CT) Computed tomography.
- Magnetic resonance imaging (MRI) Magnetic resonance imaging.
Time required
Preparation
- 5 min.
Procedure
- 15-60 min for each block to be administered, take effect and tested.
Decision taking
Criteria for choosing test
- Degree of lameness and history - if lameness is severe and a fracture Musculoskeletal: fracture - first aid is suspected do not administer nerve blocks. Diagnostic imaging is indicated instead.
- Presence or suspicion of cellulitis or infectious skin Wound: management - overview contraindicates injection.
- If strong suspicion of tarsal or stifle involvement, lower blocks can be skipped, and begin with low six- or four-point nerve block to rule out pain in the fetlock and digit.
- In horses with multi-limb lameness, always start by blocking the lamest limb.
- Local anesthetic solution:
- Lidocaine (2%) Lidocaine: shortest duration of action (30-45 min), greater tissue irritation.
- Mepivacaine Mepivacaine: duration of action is 90-120 minutes, less tissue irritation, most commonly used local anesthetic solution of diagnostic analgesia.
- Bupivacaine hydrochlorine (0.5%) Bupivacaine hydrochloride: longest duration of action (4-6 h), most commonly used for peri-operative analgesia
Requirements
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Preparation
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Technique
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Aftercare
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Outcomes
Subscribe To View
This article is available to subscribers.
Try a free trial today or contact us for more information.
Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- Pezzanite L, Contino E & Kackak C (2018) Lameness originating from the proximal metacarpus/tarsus: A review of local analgesic techniques and clinical diagnostic findings. Equine Vet Educ WileyOnline.
- Malton R & Nagy A (2015) Diffusion of radiodense contrast medium after a mid-pastern ring block. Equine Vet Educ 28 (1), 40-46 WileyOnline.
- Nagy A & Malton R (2015) Diffusion of radiodense contrast medium after perineural injection of the palmar digital nerves. Equine Vet Educ 27 (12), 648-654 WileyOnline.
- Paz C F, Magalhaes J F et al (2016) Mechanical nociceptive thresholds of dorsal laminae in horses after local anaesthesia of the palmar digital nerves or dorsal branches of the digital nerve. Vet J 214, 102-108 PubMed.
- Contino E, King M, Valdes-Martinez A & McIlwraith C W (2015) In vivo diffusion characteristics following perineural injection of the deep branch of the lateral plantar nerve with mepivacaine or iohexol in horses. Equine Vet J 47, 230-234 PubMed.
- Michou J & Leece E (2012) Sedation and analgesia in the standing horse 2. Local anaesthesia and analgesia techniques. In Pract 34 (10), 578-587 VetMedResource.
- Nagy A, Bodo G, Dyson S J, Szabo F & Barr A R S (2009) Diffusion of contrast medium after perineural injection of the palmar nerves: An in vivo and in vitro study. Equine Vet J 41 (4), 379-383 PubMed.
- Hendrickson D A & Nixon A J (1992) A lateral approach for synovial fluid aspiration and joint injection of the femoropatellar joint of the horse. Equine Vet J 24 (5), 399-401 PubMed.
Other sources of information
- Bassage L H & Ross M W (2011) Diagnostic Analgesia. In: Diagnosis and Management of Lameness in the Horse. Eds: Ross M W & Dyson S J. Elsevier Saunders, USA. pp 100-135.
- Moyer W, Schumacher J & Schumacher J (2011) Eds Equine Joint Injection and Regional Anesthesia. Academic Veterinary Solutions, Chadds Ford, USA.
- Hughes T K, Eliashar E & Smith R K W (2006) In-vitro Evaluation of a Single Injection technique for Diagnostic Analgesia of the Proximal Suspensory Ligament. In: ECVS Seville, Spain 2006 - Proceedings. Eds: Schramme M, Tremaine H, Walmsley J & Houlton J. ECVS, Zurich. pp 71-73.
- Dyson S (2006) Critical Evaluation and Review of Local Anaesthetic techniques for the Upper Hindlimb. In: Handbook of Presentations & Free Communications. BEVA Congress 2006. BEVA, UK. pp 33-34.
- Redding W R (2006) Critical Evaluation and Review of Local Anaesthetic techniques for the Lower Limb. In: Handbook of Presentations & Free Communications. BEVA Congress 2006. BEVA, UK. pp 28-30.
- Torre F (2004) How to Perform and Interpret Hind Leg Nerve Blocks in a Fractious Horse. In: Proc 43rd BEVA Congress. Equine Vet J Ltd, UK. pp 39.
- Stashak T S (2002) Perineural Anesthesia The Hindlimb. In: Adams Lameness in Horses. 5th edn. Lippincott, Williams & Wilkins, USA. pp 165-167.