Ultrasound-guided suprascapular nerve block, description of a novel supraclavicular approach.
OBJECTIVE
The suprascapular nerve (SSN) block is frequently performed for different shoulder pain conditions and for perioperative and postoperative pain control after shoulder surgery. Blind and image-guided techniques have been described, all of which target the nerve within the supraspinous fossa or at the suprascapular notch. This classic target point is not always ideal when ultrasound (US) is used because it is located deep under the muscles, and hence the nerve is not always visible. Blocking the nerve in the supraclavicular region, where it passes underneath the omohyoid muscle, could be an attractive alternative.


METHODS
In the first step, 60 volunteers were scanned with US, both in the supraclavicular and the classic target area. The visibility of the SSN in both regions was compared. In the second step, 20 needles were placed into or immediately next to the SSN in the supraclavicular region of 10 cadavers. The accuracy of needle placement was determined by injection of dye and following dissection.


RESULTS
In the supraclavicular region of volunteers, the nerve was identified in 81% of examinations (95% confidence interval [CI], 74%-88%) and located at a median depth of 8 mm (interquartile range, 6-9 mm). Near the suprascapular notch (supraspinous fossa), the nerve was unambiguously identified in 36% of examinations (95% CI, 28%-44%) (P < 0.001) and located at a median depth of 35 mm (interquartile range, 31-38 mm; P < 0.001). In the cadaver investigation, the rate of correct needle placement of the supraclavicular approach was 95% (95% CI, 86%-100%).


CONCLUSIONS
Visualization of the SSN with US is better in the supraclavicular region as compared with the supraspinous fossa. The anatomic dissections confirmed that our novel supraclavicular SSN block technique is accurate.
Pain Center, Department of Anesthesiology, University Hospital of Lausanne-CHUV, Lausanne, Switzerland. andisiegenthaler@gmail.com
Andreas
A
Siegenthaler
Bernhard
B
Moriggl
Sabine
S
Mlekusch
Juerg
J
Schliessbach
Matthias
M
Haug
Michele
M
Curatolo
Urs
U
Eichenberger
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002102:Cadaver; D016009:Chi-Square Distribution; D004396:Coloring Agents / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007208:Indocyanine Green / Q000008:administration & dosage; D007267:Injections; D008297:Male; D008875:Middle Aged; D009407:Nerve Block / Q000009:adverse effects / Q000379:methods*; D056888:Patient Positioning; D010525:Peripheral Nerves / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D012782:Shoulder / Q000294:innervation*; D016683:Supine Position; D013557:Switzerland; D018084:Ultrasonography, Interventional; D055815:Young Adult
D004396:Coloring Agents; D007208:Indocyanine Green