Contrast Spread in the Superoposterior Approach of Transforaminal Epidural Steroid Injections for Lumbosacral Radiculopathy

OBJECTIVE: To observe the contrast spread in superoposterior transforaminal epidural steroid injection (SP TFESI) and investigate the correlation between spread patterns and efficacy. METHODS: Thirty-one patients with lumbosacral radiculopathy underwent single-level TFESI under fluoroscopy. The final needle tip position was targeted toward the SP quadrant of the intervertebral foramen. To observe the spread, 1 mL of contrast material was injected, followed by a steroid injection. The contrast spread was graded anteroposteriorly and vertically in the epidural space. The effect of SP TFESI was evaluated by proportional pain score reduction. RESULTS: Levels injected were L4-5 (n=20) and L5-S1 (n=11). Seventeen cases were lateral, and 14 were central herniated disc (HD). Baseline mean visual analog scale score was 6.23. Contrast dispersed dorsally in all the cases, and 45.2% cases showed a concurrent ventral spread. The proportion of the pain reduction after 2 weeks showed no difference between the two groups. In vertical spreading analysis, mean cephalic/caudal grades were 1.40/1.55 at L4-5 level and 1.73/1.64 at L5-S1 level. The HD location had no effect on contrast dispersion. CONCLUSION: In SP TFESI, ventral contrast spread did not guarantee a better effect; however, the extent of cephalic flow in ventral expansion group correlated with the proportion of pain reduction.

Sonoanatomical Change of Phrenic Nerve According to Posture During Ultrasound-Guided Stellate Ganglion Block

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. CONCLUSION: 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.