Risk assessment of dorsal scapular nerve injury in the medial scapular area associated with upper extremity position: An ultrasonographic study.

Introduction/aims: Injuries to the dorsal scapular nerve (DSN) in the interscapular region are relatively uncommon. Physicians may therefore underestimate the risk of damage to the DSN during procedures. The aim of this study was to identify the topographic position of the DSN in the interscapular region and to identify injection positions for the upper extremities that minimize the risk of damage to the DSN during procedures.

Methods: The positional relationships between the DSN and scapula were quantified by ultrasonography in 46 healthy volunteers. The distances between the medial scapular line and DSN and the DSN depths from the surface in Zones 1 (the superior angle), 2 (the scapular spine), and 3 (between the scapular spine and inferior angle) were measured in the anatomical and contralateral shoulder touch positions (positions 1 and 2, respectively).

Results: The DSN was located further away from the medial border of the scapula and closer to the skin in position 2 than in position 1. The horizontal distance of the DSN in Zone 2 differed significantly between the two positions (0.85 ± 0.38 vs 1.23 ± 0.38, P < .001). The results suggest a safe area as just medial to the medial scapular border in Zone 2 in position 2. The safety margin should be considered at least 1.5 cm medial to the medial border of the scapula in Zone 3 in position 1.

Discussion: Performing invasive procedures in the interscapular region, appropriate individualized positioning may reduce the risk of DSN injury.