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B44 The missing superior trunk
  1. F Costa1,
  2. V Scaduto1,
  3. G Pascarella1,
  4. A Strumia1,
  5. LM Remore1,
  6. F Longo1,
  7. F Gargano1,
  8. E Sammartini1,
  9. D Sammartini1,
  10. A Tognù2 and
  11. FE Agrò1
  1. 1Fondazione Policlinico Campus Bio-Medico, Roma, Italy
  2. 2Rizzoli Orthopaedic Institute, Bologna, Italy


Background and Aims The brachial plexus is a complex anatomical structure and its variability is frequently observed. [1] Some rare arrangements of the plexus might represent a challenge even for experts in regional anesthesia.

Ultrasound scanning gave us the chance to identify and illustrate a very rare variant of the brachial plexus, never described so far (figure 1)

Methods A 29-year-old female resident was selected as a model for a live demonstration regarding ultrasound guided regional anesthesia.

Results Scanning on the right side of the neck:C5 – emerges between anterior and posterior tubercles of C5 transverse process (TP); courses anteriorly to the anterior scalene muscle (ASM), then becoming superficial, goes back, and dives into the interscalene groove alone without joining the C6 root.C6 and C7 – emerge from the corresponding TP, run inside the interscalene groove, joining each other below the transverse cervical artery (TCA), forming a sort of trunk.

C8 – becomes visible in the corner pocket and immediately joins the trunk.

T1 – never becomes visible

TCA level: C5 root and the trunk are clearly visible; a fascial sheet keeps them divided. (figure 2) (The course of the plexus is visible in a video linked to the qr code in the figure.)

The contralateral plexus was perfectly normal.

Conclusions This rare anatomical variation might represent a challenge in case of interscalene block. Since the upper trunk does not exist, a superior trunk block (STB) [3] would be impossible. An accurate ultrasound examination, aiming to recognize standardized structures [2] would be helpful.

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