Wrist blocks

Surgical approach (context: typical hand procedures done under wrist block)

Common indications: carpal tunnel release, trigger finger release, tendon repair, laceration exploration/repair, finger fracture manipulation, nail bed repair, foreign body removal, debridement
Patient positioning: supine, arm abducted on hand table; tourniquet may be used (forearm or upper arm) depending on surgeon preference
Preparation: antisepsis, draping; local infiltration by surgeon may be added at incision site
If tourniquet: limb exsanguination (Esmarch) then inflation; surgery typically 10–45 min depending on procedure

Anaesthetic management (overview)

Type of anaesthesia: regional (wrist block) ± minimal sedation; GA if unsuitable/uncooperative, extensive surgery, or prolonged tourniquet intolerance
Airway: usually none (spontaneous ventilation); if GA then SGA commonly suitable; ETT if aspiration risk, long case, or need controlled ventilation
Duration: block onset 5–20 min (agent-dependent); surgical time commonly 15–60 min; sensory duration ~2–12 h depending on LA choice and dose
How painful: wrist block itself mild–moderate; surgery usually well tolerated; major issue is tourniquet pain (esp >20–30 min) which wrist block does NOT reliably cover
Analgesia plan: paracetamol + NSAID (if appropriate) + rescue opioid; consider long-acting LA for prolonged postoperative analgesia; explain expected numbness and motor sparing
Monitoring: standard ASA; IV access recommended; full resus and intralipid available (LAST preparedness)

Definition and aims

Wrist block = blockade of terminal branches at the level of the wrist/hand to provide anaesthesia/analgesia for hand and digits
Typically targets: median nerve, ulnar nerve, superficial radial nerve; may add dorsal ulnar cutaneous branch and/or digital nerves depending on surgical site
Advantages: avoids proximal motor block (often preserves elbow/forearm movement), minimal haemodynamic effects, useful when brachial plexus block undesirable, can be done without ultrasound
Limitations: incomplete coverage if anatomy/territory misunderstood; does not cover tourniquet pain reliably; may require multiple injections

Indications and contraindications

Indications: surgery on hand/fingers (palmar or dorsal) when tourniquet time short or forearm tourniquet tolerated; ED procedures (lacerations, reductions)
Absolute contraindications: patient refusal, LA allergy (true IgE rare), infection at injection site, inability to consent/cooperate
Relative contraindications: anticoagulation/coagulopathy (lower risk than deep plexus blocks but still consider bleeding/haematoma), pre-existing neuropathy (document and discuss), severe peripheral vascular disease (avoid vasoconstrictors), inability to monitor post-block (e.g. discharge without supervision)

Relevant anatomy and sensory territories (high yield)

Median nerve: palmar surface of thumb, index, middle, and radial half of ring finger; dorsal distal phalanges/nail beds of these digits; thenar eminence
Ulnar nerve: palmar and dorsal ulnar half of ring finger + little finger; hypothenar region; dorsal ulnar cutaneous branch supplies dorsoulnar hand
Superficial radial nerve: dorsoradial hand and dorsal proximal phalanges of thumb, index, middle (variable); NOT palmar thumb pulp
Intercostobrachial nerve (T2) and medial cutaneous nerve of arm: contribute to upper arm tourniquet pain (not covered by wrist block)

Choice of local anaesthetic (LA) and dosing (principles)

Use the minimum effective volume; wrist blocks are field/terminal nerve blocks—small volumes usually adequate
Typical volumes (adult): median 3–5 mL; ulnar 3–5 mL; superficial radial 5–10 mL (subcutaneous fan); dorsal ulnar cutaneous 3–5 mL if needed
Agent selection: lidocaine 1–2% (fast onset, shorter duration), prilocaine 1% (similar), ropivacaine 0.2–0.5% or levobupivacaine 0.25–0.5% (longer duration)
Adrenaline: avoid in end-artery compromise; modern evidence suggests low-dose adrenaline in digits is often safe, but practice varies—follow local policy; avoid if PVD/Raynaud’s/sickle cell/previous revascularisation
Always calculate maximum safe dose (mg/kg) and document total dose across all injections; beware additive dosing if surgeon also infiltrates

Technique: stepwise approach (landmark ± ultrasound)

Preparation: consent (including nerve injury, infection, bleeding, LAST, incomplete block); check allergies/anticoagulation; baseline neurovascular status; asepsis; monitoring; IV access; resus drugs + intralipid available
Needle: 25G (or 22–25G) short bevel; incremental injection with frequent aspiration; avoid high pressure injection/paraesthesia
Median nerve (landmark): at proximal wrist crease between palmaris longus (if present) and flexor carpi radialis tendons; inject just deep to palmar fascia (avoid intraneural); ultrasound: nerve superficial to flexor tendons
- Pitfall: palmaris longus absent—use FCR tendon and midline landmarks; avoid injecting into flexor tendons
Ulnar nerve (landmark): just radial to flexor carpi ulnaris tendon at proximal wrist crease; ulnar artery is radial to nerve—identify pulse and stay ulnar to artery; ultrasound: nerve adjacent to artery
- Also consider dorsal ulnar cutaneous branch: subcutaneous injection dorsoulnar wrist if dorsoulnar hand surgery
Superficial radial nerve: subcutaneous ring block along dorsoradial distal forearm/wrist from radial styloid towards dorsal midline; ultrasound: small superficial branches near cephalic vein
- Avoid intravascular injection (cephalic vein) and intraneural injection (nerve is small/branching)
Digital nerve blocks (if required): inject at base of finger on each side (volar-lateral) avoiding epinephrine if vascular risk; small volumes (1–2 mL per side)
Assessment: loss of cold/light touch in appropriate territories; allow adequate onset time before incision; be ready to top up with targeted infiltration or convert to GA

Complications and management

Local anaesthetic systemic toxicity (LAST): risk increased with multiple injections, high concentration, intravascular injection (esp near ulnar artery/cephalic vein), low body weight, hepatic dysfunction
Nerve injury: intraneural injection, high pressure, paraesthesia pain; minimise by gentle technique, stop if pain/paraesthesia, consider ultrasound guidance
Vascular puncture/haematoma: ulnar artery proximity; apply pressure; caution in anticoagulated patients
Infection: aseptic technique; avoid through cellulitis
Block failure/patchy block: anatomical variation, inadequate volume, wrong plane; manage with top-up, supplemental digital blocks, surgeon infiltration, or conversion to GA
Tourniquet pain: treat with reassurance, sedation/analgesia, consider proximal block (e.g. axillary) or GA if prolonged

Postoperative considerations

Explain expected duration of numbness and limb protection (burns/trauma risk); provide written advice if day case
Analgesia: regular paracetamol ± NSAID; opioid rescue; consider rebound pain when block wears off—advise pre-emptive oral analgesia
Neurovascular check: document post-op sensation/motor function when appropriate; urgent review if severe pain, pallor, paraesthesia, or swelling (compartment syndrome/vascular compromise)

Describe how you would perform a wrist block for palmar hand surgery.

Structure: preparation → nerves to block → technique for each → assessment → rescue plan.

Preparation: consent (failure, nerve injury, infection, bleeding, LAST), check anticoagulation/allergy, baseline neuro exam, monitoring + IV access, asepsis, intralipid available
Nerves: median + ulnar + superficial radial (± dorsal ulnar cutaneous depending on incision)
Median: inject 3–5 mL at proximal wrist crease between palmaris longus and FCR (or use ultrasound); avoid intraneural injection
Ulnar: inject 3–5 mL just radial to FCU tendon but ulnar to ulnar artery pulse; aspirate frequently
Superficial radial: 5–10 mL subcutaneous fan over dorsoradial wrist/forearm; avoid cephalic vein
Assess sensory loss (cold/light touch) in territories; allow time; if patchy: targeted top-up/digital block/surgeon infiltration or convert to GA

Which nerves must be blocked for surgery on the index finger? What about the little finger?

Think palmar vs dorsal and nail bed.

Index finger: median nerve for palmar surface and much of dorsal distal phalanx/nail bed; superficial radial contributes to dorsal proximal phalanx (variable) → often block both median + superficial radial for complete coverage
Little finger: ulnar nerve for palmar and dorsal aspects; consider dorsal ulnar cutaneous branch for dorsoulnar hand involvement
If uncertainty or very distal surgery: add digital nerve blocks at base of the finger

Why might a wrist block fail to provide adequate operating conditions despite correct technique?

Common FRCA theme: anatomy, tourniquet, and incomplete territory coverage.

Wrong nerves blocked for the surgical site (e.g. dorsal ulnar cutaneous not blocked for dorsoulnar incision; superficial radial missed for dorsal radial hand)
Anatomical variation and branching (especially superficial radial nerve) leading to patchy sensory block
Inadequate volume or injection in wrong tissue plane (too superficial/deep)
Tourniquet pain (upper arm/forearm) not covered by distal blocks; requires sedation, alternative block, or GA
Time: insufficient onset time before incision

List the complications of wrist blocks and how you would reduce the risk of each.

Answer in categories: systemic, neural, vascular, infective, functional.

LAST: calculate max dose, use low volumes, incremental injection with aspiration, consider ultrasound, avoid high concentration/large total dose, monitor and have lipid rescue ready
Nerve injury: avoid intraneural injection, stop if severe pain/paraesthesia, avoid high-pressure injection, use short bevel, consider ultrasound
Vascular puncture/haematoma: identify ulnar artery pulse, use gentle technique, compress if punctured, caution with anticoagulation
Infection: strict asepsis; avoid injecting through cellulitis
Ischaemia (rare): avoid vasoconstrictor in high-risk patients; monitor perfusion; urgent assessment if pallor/coolness/pain

A patient develops tinnitus, metallic taste and perioral tingling after you start injecting for a wrist block. What do you do?

Treat as evolving LAST until proven otherwise.

Stop injecting immediately; call for help; maintain ABCs; high-flow oxygen; ensure IV access; monitor ECG/BP/SpO2
Treat seizures with benzodiazepine (avoid large propofol doses if cardiovascular instability)
Start lipid emulsion therapy per local guideline (e.g. 20% intralipid bolus then infusion); continue supportive care
If cardiac arrest: follow modified ALS for LAST (early lipid, avoid vasopressin, use reduced adrenaline doses, avoid lidocaine)
Post-event: critical care observation, document and report; counsel patient

Explain tourniquet pain and why a wrist block may not prevent it.

Key concept: tourniquet pain is mediated by proximal nerves and ischaemia-related mechanisms.

Tourniquet pain is a dull, aching pain that increases with time; related to ischaemia, C-fibre activation, and pressure on tissues
Upper arm tourniquet pain involves intercostobrachial (T2) and medial cutaneous nerve of arm; forearm tourniquet may involve musculocutaneous/medial cutaneous forearm contributions—distal wrist blocks do not block these
Management: minimise tourniquet time/pressure, consider forearm tourniquet, provide sedation/analgesia, or use more proximal block/GA

What sensory testing would you perform to confirm an adequate wrist block before incision?

Test in the correct territories rather than at the injection site.

Use cold or light touch and compare to contralateral side
Median: palmar tip of index finger (and thenar eminence)
Ulnar: palmar tip of little finger (and hypothenar region)
Superficial radial: dorsum of thumb/index web space (dorsoradial hand)

How would you modify your plan for a patient on a DOAC requiring hand surgery under wrist block?

Wrist blocks are superficial/compressible but still require risk assessment.

Assess bleeding risk of block and surgery; wrist block sites are compressible and generally lower risk than deep plexus blocks
Check timing of last DOAC dose, renal function, and local/regional guidelines; discuss with surgeon and document shared decision-making
Use ultrasound if available to reduce vascular puncture; use small-gauge needle; apply firm pressure after injections
Have a low threshold to abandon if significant bleeding/haematoma develops; ensure post-op instructions and observation

Compare wrist block with axillary brachial plexus block for hand surgery.

Frame as advantages/disadvantages and patient/surgical factors.

Wrist block advantages: simpler, superficial, minimal proximal motor block, fewer systemic effects, useful when proximal block contraindicated
Wrist block disadvantages: multiple injections, patchy coverage, does not cover tourniquet pain, may need supplementation
Axillary block advantages: more complete anaesthesia for hand/forearm; better tourniquet tolerance (especially forearm); single-site block (though multiple nerves)
Axillary block disadvantages: larger LA volume, deeper/less compressible, more motor block, potential complications (vascular puncture, nerve injury), requires more set-up/skill

A patient has persistent numbness in the median nerve distribution 24 hours after a wrist block. How do you assess and manage this?

Differentiate expected duration vs neuropraxia vs compressive pathology.

Assess: timing and LA used (expected duration), severity and distribution, motor involvement, pain/paraesthesia, vascular status, any tight dressings/cast
Examine and document neurovascular status; remove/loosen constrictive dressings if concern; consider surgical causes (haematoma, compartment syndrome) if severe pain/swelling
Escalate early to senior anaesthetist and surgical team; consider urgent imaging if compressive lesion suspected
If isolated sensory symptoms and improving: reassure, safety-net, arrange follow-up; if persistent/worsening motor deficit: urgent referral to peripheral nerve service/neurology per local pathway