Purpose Anatomic variations complicate surface landmark-guided needle placement, thereby increasing nerve blockade failure rate. and 25.3??8.0?mm, respectively, in the extended supine position. In the extended supine position, the cricoid cartilage was more cephalad than C6TP and C7TP in all patients. The distance from the cricoid cartilage to C6TP was 12.1??7.6?mm in men and 17.2??7.7?mm in women. Conclusion C6TP and C7TP are located approximately 15 and 25?mm, respectively, caudal to the cricoid cartilage in the extended supine position. Our results spotlight the fact that there can be significant anatomic variation between the extended and neutral supine positions used in stellate ganglion block, which should be kept in mind when devising easily identifiable and palpable surface landmarks. test was used to compare differences between buy 488-81-3 the extended and neutral positions. The two-sample test was used to compare differences by sex. A value <0.05 was considered to be statistically significant. Statistical Package for the Social Sciences version 20.0 software (IBM Corp., Armonk, NY, USA) was used Rabbit polyclonal to ZNF484. for all statistical analyses. Results Forty-two patients (16 men, 26 women; mean age 54.5?years; range 27C91?years) were included in the study. Demographic data buy 488-81-3 for the participants are shown in Table?1. Table?1 Demographic data of the patients In the neutral supine position, the mean distances from the cricoid cartilage to buy 488-81-3 the C6TP and C7TP were 6.0 and 15.1?mm, respectively. In the extended supine position, these distances were 15.2 and 25.3?mm, respectively. The difference between the corresponding distances in the neutral and extended supine positions was statistically significant (p?0.001 for both; Table?2). Table?2 Distances from the cricoid cartilage to the C6 transverse process or the C7 transverse process in the neutral and extended supine positions of the neck (mm) The distance from the cricoid cartilage to the C6TP was significantly different between men and women in both the neutral (p?=?0.028) and extended (p?=?0.041) supine positions. The distance from the cricoid cartilage to the C6TP was significantly different between the neutral and extended supine positions in both sexes (p?0.001 for men and women; Table?3). Table?3 Distances from the cricoid cartilage to the C6 transverse process based on sex in the neutral and extended supine positions of the neck (mm) The buy 488-81-3 distance from the cricoid cartilage to the C7TP was not significantly different between men and women in the neutral supine position (p?=?0.148) or in the extended supine position (p?=?0.132); however, it was different between the two positions in both men (p?0.001) and women (p?0.001; Table?4). Table?4 Distances from the cricoid cartilage to the C7 transverse process based on sex in the neutral and extended supine positions of the neck (mm) Discussion In this study, we evaluated the distance between the cricoid cartilage and C6TP and C7TP when patients are in the neutral supine position and the extended supine position. The cricoid cartilage was positioned, on average, more cephalad than the C6TP and C7TP in the supine position in all except seven patients (16.7?%) in the neutral supine position [six of these seven patients (94.2?%) were men], and in all patients (100?%) in the extended supine position. This means that the targets of SGB, i.e., C6TP and C7TP, should be located caudal to the cricoid cartilage in the extended position. Further research on SGB target points was performed using radiography [4]. This study analyzed the cervical vertebrae and explored the relationship between the cricoid cartilage and the C6TP. However, the X-ray of the cervical vertebrae was not obtained in the supine position, so the position was different from that used in SGB. When the patient is placed in an extended supine position for SGB, the cricoid cartilage moves cephalad. We cannot conclude that this tubercle that moves laterally from the cricoid cartilage is the C6TP. However, we can conclude that when performing SGB with the patient in an extended supine position, C6TP and C7TP are found more caudally than the cricoid cartilage. In the neutral and extended supine buy 488-81-3 positions, the distance from the cricoid cartilage to the C6TP in men was significantly different from that in women, whereas no such difference was found for the distance between the cricoid cartilage and the C7TP. Thus, the SGB injection point will be different between men and women for C6TP, but will not be different for C7TP. The reason for these results may be the anatomic difference between the sexes in the thyroid cartilage or muscular connections between the.