The Source and the Course of the Articular Branches to the T4-T8 Zygapophysial Joints.

OBJECTIVE: To define the source and the course of the articular branches to the midthoracic zygapophysial ("z") joints. DESIGN: Cadaveric dissection. SETTING: The Gross Anatomy Laboratory of the Duke University School of Medicine. SUBJECTS: Ten human cadaveric thoraces. METHODS: Gross and stereoscopic dissection of dorsal rami T4-T8 was performed bilaterally on 10 adult embalmed cadavers. The medial and lateral branches were traced to their origins from the dorsal rami, and the course of the articular nerves was documented through digital photography. Radio-opaque wire (20 gauge) was applied to the nerves. Fluoroscopic images were obtained to delineate their radiographic course with respect to osseous landmarks. RESULTS: Forty-eight inferior articular branches were identified. Three (6.3%) originated from the medial branch and 44 (91.7%) from the dorsal ramus. One was indeterminate. Fifty-one superior articular branches were identified. Eight (15.7%) originated from the medial branch and 43 (84.3%) from the dorsal ramus. In 12% of cases (6/50), there was side-to-side asymmetry in the origins of the articular branches. Nerves were commonly suspended in the intertransverse space. The articular branches contacted an osseous structure in only 39% of cases. As previously reported, a "descending branch" was not identified in any specimen. CONCLUSIONS: Articular branches to the T4-T8 z-joints have substantial inter- and intraspecimen variability of origin. They typically arise from the dorsal ramus rather than the medial branch and frequently do not contact any osseous structure to allow percutaneous needle placement.

Forgotten Branch of the Intercostal Nerve: Implication for Cryoablation Nerve Block for Pectus Excavatum Repair.

BACKGROUND: We first utilized and reported on the use of cryoanalgesia for postoperative pain control for Nuss procedure in 2016. We hypothesized that postoperative pain control could be optimized if the intercostal nerve anatomy is better understood. To test this hypothesis, human cadavers were dissected to elucidate the intercostal nerve anatomy. Cryoablation technique was modified. METHODS: Cadaver Study: Adult cadavers were used to visualize the branching patterns of the intercostal nerves. Cryoablation: Posterior to the mid-axillary line for intercostal nerves 4, 5, 6 and 7, main intercostal nerve, lateral cutaneous branch and collateral branch were cryoablated under thoracoscopic view. Verbal pain scores were obtained from patients one day after the procedure. RESULTS: The study results were obtained during the years 2021 and 2022. Eleven cadavers were dissected. The path of the main intercostal and lateral cutaneous branch lie on the inferior rib surface of the corresponding intercostal nerve. Total of 92 lateral cutaneous branches of the intercostal nerve were dissected and measured as they pierced the intercostal muscle. Most lateral cutaneous branches of the intercostal nerve pierced the intercostal muscle anterior to midaxillary line 78.3%, posterior to midaxillary line 18.5% or on the midaxillary line 3.3%. The collateral branch of the intercostal nerve separated near the spine and traveled along the superior surface of the next inferior rib. Cryoablation: 22 male patients underwent Nuss procedure with cryoanalgesia. Median age of the patients was 15 years (IQR: 2), median Haller index was 3.73 (IQR: 0.85), median pain score (0-10 maximum pain) was 1 (IQR: 1.75). CONCLUSION: Cryoablation of the intercostal nerve and its two branches improves pain control after a Nuss procedure. LEVEL OF EVIDENCE: Level 4. TYPE OF STUDY: Observational study.