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BackgroundCervical erector spinae plane (ESP) block has been described to anesthetize the brachial plexus (BP), however, the mechanism of its clinical effect remains unknown. As the prevertebral fascia encloses the phrenic nerves, BP and erector spinae muscles to form a prevertebral compartment, a local anesthetic injected in the cervical ESP could potentially spread throughout the prevertebral compartment. This study utilizes cadaveric models to evaluate the spread of ESP injections at the C6 and C7 levels to determine whether the injection can reach the BP and its surrounding structures.MethodsFor each of the five cadavers, an ESP injection posterior to the transverse process of C6 was performed on one side, and an ESP injection posterior to the transverse process of C7 was performed on the contralateral side. Injections were performed under ultrasound guidance and consisted of a 20 mL mixture of 18 mL water and 2 mL India ink. After cadaver dissection, craniocaudal and medial-lateral extent of the dye spread in relation to musculoskeletal anatomy as well as direct staining relevant nerves was recorded. The degree of dye staining was categorized as “deep,” “faint,” or “no.”ResultsThe phrenic nerve was deeply stained in 1 injection and faintly stained in 2 injections. Caudally, variable staining of C8 (100%) and T1 (50%) roots were seen. Faintly staining at C4 root was only seen in one sample (10%). There was variable staining of the anterior scalene muscles (40%) anterior to the BP and the rhomboid intercostal plane caudally (30%).ConclusionsUltrasound-guided cervical (C6 and C7) ESP injections consistently stain the roots of the BP and dorsal rami. This study supports the notion that the cervical ESP block has the potential to provide analgesia for patients undergoing shoulder and cervical spine surgeries.

Background: The Rhomboid intercostal and Subserratus plane (RISS) block is a new interfascial block that has shown promising results for abdominal and thoracic surgeries. Our objective was to describe improved analgesia and dermatomal coverage within the patients who received bilateral ARISS blocks after major abdominal surgery. Case: Twenty-one patients who underwent abdominal surgery received the rhomboid intercostal component of the block at the level of T5 to T6 and the subserratus component block was performed at T6 to T9 level (either single injections or catheter infusion). RISS blocks provided effective postoperative analgesia. There was a variation of dermatomal coverage ranging from T3 to T12. Patients reported a high satisfaction rate from pain management. Conclusions: RISS block in abdominal surgery seems to have an important role in perioperative pain management complementing the multimodal analgesic regimen. To determine the efficacy of RISS block for abdominal surgery, further randomized control trials are needed.