Traditional regional anesthesia for hand surgery has historically relied on brachial plexus blockade via interscalene, supraclavicular, infraclavicular, or axillary approaches. These proximal techniques anesthetize the terminal branches of the plexus en bloc, producing dense sensory and motor blockade of the upper extremity. While highly effective for surgical anesthesia, they predictably result in global limb weakness and may be associated with complications such as pneumothorax and phrenic nerve–related diaphragmatic paralysis, particularly with interscalene and supraclavicular approaches (1). With advances in regional anesthesia, motor-sparing blocks have become increasingly preferred for hand surgery.
Motor-sparing forearm blocks are grounded in precise anatomical localization and ultrasound-guided deposition of low volumes of local anesthetic around individual terminal nerves rather than within the brachial plexus sheath. This selective strategy limits proximal motor involvement while maintaining dense sensory anesthesia of the hand. The median, ulnar, superficial radial, and lateral antebrachial cutaneous nerves are targeted at distal forearm or wrist levels where motor branches have largely separated from sensory components. Chin et al. describe ultrasound-guided motor-sparing forearm blocks as an approach that aligns anesthetic planning with surgical objectives, especially when preserving movement improves procedural accuracy (1).
The median nerve block is typically performed in the middle of the forearm, below the flexor digitorum superficialis and profundus muscles, to minimize spread to the motor branches that supply the forearm flexors. Under ultrasound visualization, local anesthetic is deposited within the surrounding fascial plane to achieve volar radial hand anesthesia (2). The ulnar nerve is blocked in the distal half of the forearm, proximal to the dorsal and palmar cutaneous branches yet distal enough to spare motor innervation to the flexor carpi ulnaris. This positioning provides sensory blockade of the ulnar digits without compromising intrinsic or extrinsic muscle strength. The superficial radial nerve, being purely sensory, is anesthetized through subcutaneous infiltration along the dorsolateral wrist. Because the thumb base and lateral wrist may also receive innervation from the lateral antebrachial cutaneous nerves, a supplemental subcutaneous injection superficial to the brachioradialis muscle is frequently added to ensure complete coverage (2).
Motor-sparing regional anesthesia is particularly advantageous in hand surgery cases that require a dynamic intraoperative assessment. For example, in flexor and extensor tendon repairs, active motion preservation enables surgeons to evaluate tendon glide, detect gapping at the repair site, and optimize tensioning before closing the incision. Similarly, tendon transfers and reconstructive procedures benefit from immediate assessment of excursion and functional positioning, which cannot be performed under complete motor blockade. Trigger finger release and selective nerve decompression also lend themselves to this approach because real-time feedback confirms the restoration of motion without the interference of limb paralysis. Ultrasound-guided distal blocks have demonstrated effective analgesia with minimal motor impairment in ambulatory hand surgery, supporting early mobilization and discharge (3). By preserving forearm muscle function while providing targeted sensory anesthesia, this approach aligns with modern ambulatory and “wide-awake” surgical models.
Ultrasound guidance allows visualization of neural structures, adjacent vessels, and fascial planes. This facilitates low-volume anesthetic deposition and reduces the risk of vascular puncture or intraneural injection (3). Using a small-gauge needle, such as a 25-gauge needle, minimizes patient discomfort during infiltration. The needle tip should be positioned tangentially adjacent to the nerve within the perineural sheath. Incremental injection confirms circumferential spread rather than direct neural penetration. When executed carefully, motor-sparing regional anesthesia is a function-preserving, anatomically rational alternative to traditional brachial plexus blockade in modern hand surgery.
References
1. Kowa CY, Ravarian B, Baltzer H, Chin KJ. Ultrasound-guided motor-sparing forearm blocks for hand surgery: surgical and anesthetic perspectives. Reg Anesth Pain Med. Published online December 13, 2025. doi:10.1136/rapm-2025-107388
2. Sehmbi H, Madjdpour C, Shah UJ, Chin KJ. Ultrasound guided distal peripheral nerve block of the upper limb: A technical review. J Anaesthesiol Clin Pharmacol. 2015;31(3):296-307. doi:10.4103/0970-9185.161654
3. Dufeu N, Marchand-Maillet F, Atchabahian A, et al. Efficacy and safety of ultrasound-guided distal blocks for analgesia without motor blockade after ambulatory hand surgery. J Hand Surg Am. 2014;39(4):737-743. doi:10.1016/j.jhsa.2014.01.011
Traditional regional anesthesia for hand surgery has historically relied on brachial plexus blockade via interscalene, supraclavicular, infraclavicular, or axillary approaches. These proximal techniques anesthetize the terminal branches of the plexus en bloc, producing dense sensory and motor blockade of the upper extremity. While highly effective for surgical anesthesia, they predictably result in global limb weakness and may be associated with complications such as pneumothorax and phrenic nerve–related diaphragmatic paralysis, particularly with interscalene and supraclavicular approaches (1). With advances in regional anesthesia, motor-sparing blocks have become increasingly preferred for hand surgery.
Motor-sparing forearm blocks are grounded in precise anatomical localization and ultrasound-guided deposition of low volumes of local anesthetic around individual terminal nerves rather than within the brachial plexus sheath. This selective strategy limits proximal motor involvement while maintaining dense sensory anesthesia of the hand. The median, ulnar, superficial radial, and lateral antebrachial cutaneous nerves are targeted at distal forearm or wrist levels where motor branches have largely separated from sensory components. Chin et al. describe ultrasound-guided motor-sparing forearm blocks as an approach that aligns anesthetic planning with surgical objectives, especially when preserving movement improves procedural accuracy (1).
The median nerve block is typically performed in the middle of the forearm, below the flexor digitorum superficialis and profundus muscles, to minimize spread to the motor branches that supply the forearm flexors. Under ultrasound visualization, local anesthetic is deposited within the surrounding fascial plane to achieve volar radial hand anesthesia (2). The ulnar nerve is blocked in the distal half of the forearm, proximal to the dorsal and palmar cutaneous branches yet distal enough to spare motor innervation to the flexor carpi ulnaris. This positioning provides sensory blockade of the ulnar digits without compromising intrinsic or extrinsic muscle strength. The superficial radial nerve, being purely sensory, is anesthetized through subcutaneous infiltration along the dorsolateral wrist. Because the thumb base and lateral wrist may also receive innervation from the lateral antebrachial cutaneous nerves, a supplemental subcutaneous injection superficial to the brachioradialis muscle is frequently added to ensure complete coverage (2).
Motor-sparing regional anesthesia is particularly advantageous in hand surgery cases that require a dynamic intraoperative assessment. For example, in flexor and extensor tendon repairs, active motion preservation enables surgeons to evaluate tendon glide, detect gapping at the repair site, and optimize tensioning before closing the incision. Similarly, tendon transfers and reconstructive procedures benefit from immediate assessment of excursion and functional positioning, which cannot be performed under complete motor blockade. Trigger finger release and selective nerve decompression also lend themselves to this approach because real-time feedback confirms the restoration of motion without the interference of limb paralysis. Ultrasound-guided distal blocks have demonstrated effective analgesia with minimal motor impairment in ambulatory hand surgery, supporting early mobilization and discharge (3). By preserving forearm muscle function while providing targeted sensory anesthesia, this approach aligns with modern ambulatory and “wide-awake” surgical models.
Ultrasound guidance allows visualization of neural structures, adjacent vessels, and fascial planes. This facilitates low-volume anesthetic deposition and reduces the risk of vascular puncture or intraneural injection (3). Using a small-gauge needle, such as a 25-gauge needle, minimizes patient discomfort during infiltration. The needle tip should be positioned tangentially adjacent to the nerve within the perineural sheath. Incremental injection confirms circumferential spread rather than direct neural penetration. When executed carefully, motor-sparing regional anesthesia is a function-preserving, anatomically rational alternative to traditional brachial plexus blockade in modern hand surgery.
References
1. Kowa CY, Ravarian B, Baltzer H, Chin KJ. Ultrasound-guided motor-sparing forearm blocks for hand surgery: surgical and anesthetic perspectives. Reg Anesth Pain Med. Published online December 13, 2025. doi:10.1136/rapm-2025-107388
2. Sehmbi H, Madjdpour C, Shah UJ, Chin KJ. Ultrasound guided distal peripheral nerve block of the upper limb: A technical review. J Anaesthesiol Clin Pharmacol. 2015;31(3):296-307. doi:10.4103/0970-9185.161654
3. Dufeu N, Marchand-Maillet F, Atchabahian A, et al. Efficacy and safety of ultrasound-guided distal blocks for analgesia without motor blockade after ambulatory hand surgery. J Hand Surg Am. 2014;39(4):737-743. doi:10.1016/j.jhsa.2014.01.011
