Main indications for block
The Plexus brachialis block is used in topographic anatomy and operative surgery to address two main clinical objectives. First, it is used as nerve block anesthesia for various surgeries on the upper extremity, as well as for surgical interventions directly on the shoulder joint. Second, this procedure is indicated for patients diagnosed with severe upper extremity neuralgia that is refractory to standard treatment.
Technique (supraclavicular approach)
To successfully perform the anesthesia, it is essential to strictly follow the algorithmic steps and rely on bony landmarks. The procedure is performed in several stages:
- Patient position: The patient should be seated. A critical condition is that the arm on the side of the injection must be firmly pulled downward. This ensures optimal tissue tension and stabilization of anatomical structures.
- Determining the injection site: The needle is inserted 1.5 cm above the midpoint of the upper clavicular border.
- Needle trajectory: The vector of needle advancement must be directed precisely toward the spinous process of the third thoracic vertebra.
- Depth of insertion: The needle is advanced to a depth of 3 cm. At this level lies the adipose tissue surrounding the trunks of the plexus.
- Administration of the anesthetic: 20 ml of a 2% novocaine solution is injected into this adipose tissue.
Characteristics and onset time of anesthesia
The clinical picture of pain relief directly depends on the precision of solution placement relative to the nerve trunks.
- Standard block progression: When the drug is properly injected into the adipose tissue surrounding the Plexus brachialis, full anesthesia develops gradually—on average after 30 minutes. The total duration of effective pain relief ranges from 1.5 to 2 hours.
- Direct contact with the plexus: If the needle tip perforates the sheaths and the solution enters the plexus itself, the clinical picture changes. At this moment, the patient experiences characteristic pain irradiation (a shooting sensation) down the limb. In such cases, anesthesia occurs immediately.
Complications and their prevention
The primary anatomical hazard of the supraclavicular approach is related to the close proximity of the pleural dome to the injection site.
The most formidable complication is accidental pleural injury, which inevitably leads to the development of pneumothorax. To avoid this life-threatening condition, topographical anatomy suggests modifying the classic injection site: for reliable prevention of pleural injury, the needle should be inserted significantly higher—3 cm above the midpoint of the upper clavicular border.
Briefly: answers to topical questions
From the anterior rami of which spinal nerves is the brachial plexus formed?
The brachial plexus is formed from the anterior rami of the spinal nerves of the lower cervical and upper thoracic segments. The following structures of the peripheral nervous system participate in its formation:
- Cervical spinal nerves — anterior rami from the fifth to the eighth (C5–C8).
- Thoracic spinal nerves — anterior ramus of the first thoracic nerve (Th1).
These rami subsequently form the trunks and cords of the plexus to innervate the upper extremity.
Which long branches of the brachial plexus innervate the free upper extremity?
The long branches of the brachial plexus innervating the free upper extremity are formed from its three cords.
- Musculocutaneous nerve (n. musculocutaneus) and the lateral root of the median nerve — from the lateral cord.
- Ulnar nerve (n. ulnaris), medial cutaneous nerves of the arm and forearm (n. cutaneus brachii medialis, n. cutaneus antebrachii medialis), and the medial root of the median nerve — from the medial cord.
- Median nerve (n. medianus) — formed by the union of the medial and lateral roots.
- Radial nerve (n. radialis) and axillary nerve (n. axillaris) — from the posterior cord.
Which local anesthetics and at what concentrations are used for brachial plexus block?
Solutions of local anesthetics of the amide and ester groups in various concentrations are used for brachial plexus block.
- Novocaine (procaine) — a 2% solution in a volume of 20 ml is used (for the supraclavicular approach).
- Ropivacaine — a 0.2% solution is used for continuous infusion at a rate of 4–6 ml/h.
- Levobupivacaine — a 0.2% solution is used for continuous infusion at a rate of 4–6 ml/h.
What approaches exist for nerve block anesthesia of the brachial plexus, besides the supraclavicular one?
In addition to the supraclavicular approach, interscalene and axillary approaches are used for nerve block anesthesia of the brachial plexus.
- Interscalene approach — performed in the projection of the lateral cervical triangle; the interscalene space serves as the landmark.
- Axillary approach — used for brachial plexus block via the axillary region.
To memorize the technique, use the "Rule of Threes": the needle insertion depth is 3 cm, the needle is directed toward the spinous process of the third thoracic vertebra, and to prevent pneumothorax, the injection site is elevated 3 cm above the clavicle.
Class and exam questions
How long after the administration of novocaine into the tissue does anesthesia occur?
With proper injection of the anesthetic into the tissue surrounding the plexus, anesthesia occurs within 30 minutes.
How to determine that the needle has directly entered the nerve plexus?
Upon direct contact with the plexus, the patient feels sharp pain radiating into the limb, and the anesthetic effect develops immediately, without a waiting period.
Which complication is most characteristic of the supraclavicular approach?
The most dangerous complication is pleural injury, which leads to the onset of pneumothorax.
What else to study on this topic
- Topographical anatomy of the spinous process of the third thoracic vertebra as a landmark
- Structure of fascial spaces surrounding the trunks of the Plexus brachialis
- Topography of the pleural dome and the mechanism of pneumothorax development
- Etiology of refractory upper extremity neuralgia
- Alternative approaches for upper extremity nerve block anesthesia
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