Serratus Posterior Superior Intercostal Plane Block: A Technical Report on the Description of a Novel Periparavertebral Block for Thoracic Pain.

Background and objective We report a novel block technique aimed to provide thoracic analgesia: the serratus posterior superior intercostal plane (SPSIP) block. Design A cadaveric evaluation along with a retrospective case series evaluating the potential analgesic effect of the SPSIP block. This study included one unembalmed cadaver and five patients. Interventions Bilateral ultrasound-guided SPSIP block was used on cadavers with 30 mL of methylene blue 0.5% on each side; single-injection SPSIP blocks were used in patients. To measure results, dye spread was used in the cadaver, and dermatomal/pain score evaluation was used in patients. Main results Anatomical investigation in one unembalmed cadaver shows that its mechanism of action covers the rhomboid major muscle, erector spinae muscle, the deep fascia of the subscapularis/serratus anterior muscles, and intercostal nerves. In our patients, SPSIP resulted in an almost complete sensory block in the back of the neck, shoulder, and hemithorax. Conclusion Our cadaveric study shows extensive dye spread from C7 to T7. Patients who were administrated SPSIP block reported consistent dermatomal blockade from C3 to T10 levels of the hemitorax. The SPSIP block seems to be a safe, simple, and effective technique for thoracic analgesia.