Regional Anesthesia and Peripheral Nerve Blocks
Regional anesthesia (conduction anesthesia) is the practice of producing reversible loss of sensation in a defined part of the body by interrupting nerve conduction with a local anesthetic placed near nerves, nerve plexuses, or the neuraxis, while the patient may remain awake or lightly sedated. It encompasses neuraxial techniques (spinal and epidural) and peripheral nerve blocks, and it has been transformed in recent decades by ultrasound guidance.
Definition
Regional anesthesia is the reversible interruption of nerve conduction by local anesthetic agents applied to peripheral nerves, plexuses, or the spinal/epidural space, producing analgesia or anesthesia confined to the region those nerves supply.
Scope
This area orients the reader to conduction anesthesia as a branch of anesthesiology. It groups the pharmacology of local anesthetics and their systemic toxicity, neuraxial (spinal and epidural) techniques, peripheral nerve blocks, the role of ultrasound guidance, and the patient-selection and technical judgements that govern safe practice. It is a reference and educational overview of how these techniques work and how their evidence base is organized, not a procedural manual or a source of dosing or treatment instructions.
Sub-topics
Key concepts
- Conduction (regional) anesthesia
- Local anesthetic blockade of voltage-gated sodium channels
- Neuraxial anesthesia (spinal and epidural)
- Peripheral nerve and plexus blocks
- Ultrasound-guided needle and catheter placement
- Local anesthetic systemic toxicity (LAST)
- Differential and dynamic sensory-motor block
- Single-injection versus continuous catheter techniques
Mechanisms
Local anesthetics produce regional blockade by binding voltage-gated sodium channels on nerve membranes and preventing the rise in sodium conductance needed to propagate an action potential, so impulses fail to cross the blocked segment (Marhofer 2005; Miller's Anesthesia). Where the drug is deposited determines the territory anesthetized: near a single peripheral nerve or plexus for a peripheral block, or in the subarachnoid or epidural space for neuraxial anesthesia, where spread along the neuraxis blocks multiple spinal segments. Because nerve fibers differ in diameter and myelination, sensory, motor, and autonomic functions are not blocked equally, producing the differential block characteristic of these techniques.
Clinical relevance
Regional techniques are used to provide surgical anesthesia and to manage acute and chronic pain across many surgical and obstetric settings, and they are a major component of multimodal, opioid-sparing analgesia. This entry describes the field as a reference subject — how the techniques are categorized and studied — and does not provide procedural, dosing, or individualized patient-care recommendations.
Evidence & guidelines
Practice in this area is informed by structured advisories from professional societies, including the American Society of Regional Anesthesia and Pain Medicine (ASRA) advisories on local anesthetic systemic toxicity and on neurologic complications (Neal 2018; Neal 2015). These documents synthesize observational evidence and expert consensus on safety, monitoring, and complication management, and are periodically updated.
History
Conduction anesthesia began with the introduction of cocaine as a topical and injected local anesthetic in the 1880s, followed by spinal anesthesia and the synthesis of safer ester and amide local anesthetics through the twentieth century (Miller's Anesthesia). The development of nerve-localization methods — from paresthesia and fascial-click techniques to peripheral nerve stimulation and, more recently, real-time ultrasound guidance — progressively improved the precision and safety of nerve blocks (Marhofer 2005).
Related topics
Seminal works
- neal-2018-last
- marhofer-2005-us
- neal-2015-neuro
Frequently asked questions
- How does regional anesthesia differ from general anesthesia?
- Regional anesthesia blocks conduction in specific nerves so only a region of the body loses sensation, and the patient may stay awake; general anesthesia produces a controlled, reversible loss of consciousness affecting the whole body.
- What are the two broad categories of regional anesthesia?
- Neuraxial techniques, which place local anesthetic in the spinal (subarachnoid) or epidural space, and peripheral nerve blocks, which target individual nerves or plexuses away from the neuraxis.