UOTW #76

A 45 year old male presents with shortness of breath following a right rotator cuff repair surgery. These scans were obtained at the mid axillary line at the level of T4.



ANSWER:  Phrenic nerve paralysis following interscalene brachial plexus block.

  • This patient presents with increasing shortness of breath following a right rotator cuff surgical repair after which he had a continuous nerve block catheter placed next to the interscalene brachial plexus. The anesthetic affected the phrenic nerve, which is responsible for supplying motor innervation to the diaphragm.1
  • Peripheral nerve blocks are often performed to assist in post-operative analgesia, reducing the need for opioids and increasing patient satisfaction.2
  • The technique involves identifying the nerve roots C5-7 between the anterior and middle scalene muscles.3  The phrenic nerve arises from nerve rooms C2-4, which are in close proximity to where the interscalene brachial plexus lies.4
  • Phrenic nerve paresis has been well documented in the anesthesia literature, with some sources stating that it occurs in up to 100% of cases if large volume blocks are used.5
  • Although more common in larger volume blocks and when indwelling catheters are used, there have been reported instances of phrenic nerve paresis occurring after emergency medicine performed interscalene brachial plexus blocks.6
  • The expected complication of transient phrenic nerve paresis after an interscalene brachial plexus block should be carefully taken into account when assessing the risk benefit ratio for the patient.


  • After identification of right diaphragmatic paralysis, the indwelling interscalene brachial plexus catheter was removed per anesthesia and orthopedic recommendations.
  • The patient was discharged, and reported partial resolution of symptoms.


  1. Smith HM, Duncan CM, Hebl JR. Clinical utility of low-volume ultrasound-guided interscalene blockade: contraindications reconsidered. Journal of ultrasound in medicine. 28(9):1251-8. 2009. [pubmed]
  2. Bowens C, Sripada R. Regional blockade of the shoulder: approaches and outcomes. Anesthesiology research and practice. 2012:971963. 2012. [pubmed]
  3. Falyar CR, Grossman EC. Ultrasound-guided interscalene-supraclavicular block for an intramedullary nailing of a pathologic humeral fracture: practical application of ultrasound-guided regional anesthesia. AANA journal. 82(3):219-22. 2014. [pubmed]
  4. Jariwala A, Kumar BC, Coventry DM. Sudden severe postoperative dyspnea following shoulder surgery: Remember inadvertent phrenic nerve block due to interscalene brachial plexus block. International journal of shoulder surgery. 8(2):51-4. 2014. [pubmed]
  5. Sala-Blanch X, Lázaro JR, Correa J, Gómez-Fernandez M. Phrenic nerve block caused by interscalene brachial plexus block: effects of digital pressure and a low volume of local anesthetic. Regional anesthesia and pain medicine. 24(3):231-5. 1999. [pubmed]
  6. Mantuani D, Nagdev A. Sonographic evaluation of a paralyzed hemidiaphragm from ultrasound-guided interscalene brachial plexus nerve block. The American journal of emergency medicine. 30(9):2099.e5-7. 2012. [pubmed]