Anaes · Regional anaesthesia
Interscalene brachial plexus block
Also known as Interscalene block · ISB · Shoulder block · Interscalene brachial plexus block
Exam-exhaustive interscalene block: indications for shoulder surgery, C5–C7 coverage with ulnar spare, near-universal phrenic palsy, pneumothorax and LAST risks, low-volume and superior-trunk alternatives, and ultrasound technique for ANZCA Final and equivalents.
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Red flags
- Ipsilateral hemidiaphragmatic paresis is expected — contraindicated if the patient cannot tolerate loss of one hemidiaphragm (severe respiratory disease, contralateral phrenic palsy).
- Vertebral/carotid intravascular injection can produce rapid LAST — aspirate, fractionate, lipid available.
- Medial needle trajectory risks neuraxial spread; caudal trajectory risks pneumothorax.
- Ulnar (C8–T1) sparing — wrong block for hand/forearm surgery.
- Horner syndrome and recurrent laryngeal nerve block are usually transient but require counselling.
Meet the patient
A sixty-eight-year-old with severe chronic obstructive pulmonary disease is listed for arthroscopic rotator cuff repair, and the surgeon would like a regional block for analgesia. The block that fits the surgery is the interscalene block; the problem is that the same block paralyses half her diaphrag — and her lungs cannot spare it.[1]
The two questions that decide her plan are the two that decide every interscalene: will this block cover the surgery? (it will — shoulder is its home territory) and can her diaphrag take the hit? (it cannot, so you reach for a diaphragm-sparing alternative). Hold those two and the technique below slots into place.[1]
References6ShowHide
- [1]Riazi S, Carmichael N, Awad I, et al. Effect of local anaesthetic volume (20 vs 5 ml) on the efficacy and respiratory consequences of ultrasound-guided interscalene brachial plexus block. Br J Anaesth, 2008.PMID 18682410
- [2]da Cunha DF, et al. Incidence of hemidiaphragmatic paralysis in superior trunk versus interscalene block upper limb surgeries: a systematic review, meta-analysis, and trial sequential analysis Anesth Pain Med (Seoul), 2026.PMID 42130052
- [3]Verbeke AL, et al. The diaphragm-sparing effect of interscalene block with a low-volume of ropivacaine 0.1% vs. 0.5%: A double-blind, controlled, randomised trial. Eur J Anaesthesiol Intensive Care, 2026.PMID 42244823
- [4]Neal JM, et al. The Third American Society of Regional Anesthesia and Pain Medicine Practice Advisory on Local Anesthetic Systemic Toxicity: Executive Summary 2017. Reg Anesth Pain Med, 2018.PMID 29356773
- [5]Albrecht E, Renard Y, Desai N Intravenous versus perineural dexamethasone to prolong analgesia after interscalene brachial plexus block: a systematic review with meta-analysis and trial sequential analysis. Br J Anaesth, 2024.PMID 38782616
- [6]Franco CD, Williams JM Ultrasound-Guided Interscalene Block: Reevaluation of the "Stoplight" Sign and Clinical Implications. Reg Anesth Pain Med, 2016.PMID 27203394