Accuracy of ultrasound-guided suprascapular nerve block measured with neurostimulation

Although the use of ultrasound (US) to perform suprascapular nerve block (SsNB) is rapidly gaining popularity, information about its accuracy is still lacking. The aim of this study was to investigate the proximity of the needle to suprascapular nerve under US guidance by means of neurostimulation current intensity in SsNB. The patients who were referred for SSnB due to shoulder pain were included in the study. The patients were placed in sitting position, and when the operator decided that the needle was in the correct place under US guidance, the time duration until that time and the current amplitude in that location were recorded. Current intensity was obtained by gradually increasing the amplitude until patient feels parestesia over the shoulder area or contractions of the supraspinatus or infraspinatus muscles. Out of 27 patients, in five patients current intensity was between 0.1 and 0.8 mA (successful) and time duration was 2.52 ± 1.67 min in this group; in 19 patients, current intensity was between 0.9 and 1.4 mA (semi-successful) and time duration was 1.86 ± 1.02 min in this group; in three patients, current intensity was ≥1.5 mA (unsuccessful) and time duration was 2.41 ± 1.02 min in this group. Our results show that the needle could not reach sufficient proximity to the suprascapular nerve with only US guidance by means of NS current intensity.