Background and Objective Bleeding into the retropharyngeal space is a potential complication in stellate ganglion block (SGB). Retropharyngeal hematoma formation is considered to be due to damage of small arteries in the region, although only scanty details of the region are available. The aim of this study was to map the risk blood vessels in the retropharyngeal space to avoid accidental damage during SGB. Methods Contrast-enhanced 3-dimensional computed tomography images performed on 80 patients were reanalyzed retrospectively to construct detailed map of cervical blood vessels that are prone to damage and bleeding during SGB. Results Of the 160 bilateral necks, 6 (3.8%) and 82 (51.3%) small arteries were identified in the medial portions of the ventral surface of the transverse processes of the sixth and seventh cervical vertebrae, respectively. In particular, 5 of the 6 small arteries detected in the medial portion of the ventral surface of the transverse process of the sixth cervical vertebra were the inferior thyroid artery (ITA). Of the 160 vertebral arteries, 2 arteries were missing, 4 (2.5%) entered the transverse foramen of the fifth cervical vertebra, whereas 1 artery (0.6%) entered the transverse foramen of the fourth cervical vertebra. Conclusions Three-dimensional computed tomography identified the ITA in the medial portion of the ventral surface of the transverse process of the sixth cervical vertebra. The risk vessels of retropharyngeal hematoma during SGB could include the ITA.
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