title: Sonoanatomical Change of Phrenic Nerve According to Posture During Ultrasound-Guided Stellate Ganglion Block.
abstract: OBJECTIVE
  To evaluate the risk of phrenic nerve injury during ultrasound-guided stellate ganglion block (US-SGB) according to sonoanatomy of the phrenic nerve, and determine a safer posture for needle insertion by assessing its relationship with surrounding structure according to positional change.
  
  
  METHODS
  Twenty-nine healthy volunteers were recruited and underwent ultrasound in two postures, i.e., supine position with the neck extension and head rotation, and lateral decubitus position. The transducer was placed at the anterior tubercle of the C6 level to identify phrenic nerve. The cross-sectional area (CSA), depth from skin, distance between phrenic nerve and anterior tubercle of C6 transverse process, and the angle formed by anterior tubercle, posterior tubercle and phrenic nerve were measured.
  
  
  RESULTS
  The phrenic nerve was clearly identified in the intermuscular fascia layer between the anterior scalene and sternocleidomastoid muscles. The distance between the phrenic nerve and anterior tubercle was 10.33±3.20 mm with the supine position and 9.20±3.31 mm with the lateral decubitus position, respectively. The mean CSA and skin depth of phrenic nerve were not statistically different between the two positions. The angle with the supine position was 48.37°±27.43°, and 58.89°±30.02° with the lateral decubitus position. The difference of angle between the two positions was statistically significant.
  
  
  CONCLUSIONS
  Ultrasound is a useful tool for assessing the phrenic nerve and its anatomical relation with other cervical structures. In addition, lateral decubitus position seems to be safer by providing wider angle for needle insertion than the supine position in US-SGB.
authors.affiliation: Department of Physical Medicine and Rehabilitation, Korea University Guro Hospital, Seoul, Korea.
authors.forename: Eui Soo
authors.initials: ES
authors.lastname: Joeng
authors.affiliation: Department of Physical Medicine and Rehabilitation, Korea University Guro Hospital, Seoul, Korea.
authors.forename: Young Cheol
authors.initials: YC
authors.lastname: Jeong
authors.affiliation: Department of Physical Medicine and Rehabilitation, Korea University Guro Hospital, Seoul, Korea.
authors.forename: Bum Jun
authors.initials: BJ
authors.lastname: Park
authors.affiliation: Department of Physical Medicine and Rehabilitation, Korea University Guro Hospital, Seoul, Korea.
authors.forename: Seok
authors.initials: S
authors.lastname: Kang
authors.affiliation: Department of Physical Medicine and Rehabilitation, Korea University Guro Hospital, Seoul, Korea.
authors.forename: Seung Nam
authors.initials: SN
authors.lastname: Yang
authors.affiliation: Department of Physical Medicine and Rehabilitation, Korea University Guro Hospital, Seoul, Korea.
authors.forename: Joon Shik
authors.initials: JS
authors.lastname: Yoon
keywords: Phrenic nerve; Posture; Stellate ganglion; Ultrasound