The erector spinae plane block causes only cutaneous sensory loss on ipsilateral posterior thorax: a prospective observational volunteer study

Abstract

Background: Ultrasound-guided erector spine plane (ESP) block is widely used in perioperative analgesia for back, chest and abdominal surgery. The extent and distribution of this block remain controversial. This study was performed to assess the analgesia range of an ultrasound-guided ESP block. Methods: This prospective observational volunteer study consisted of 12 healthy volunteers. All volunteers received an erector spinae plane block at the left T5 transverse process using real-time ultrasound guidance. Measured the cutaneous sensory loss area (CSLA) and cutaneous sensory declination area (CSDA) using cold stimulation at different time points after blockade until its disappearance. The CSLA and CSDA were mapped and then calculated. The block range was described by spinous process level and lateral extension. The effective block duration for each volunteer was determined and recorded. Results: The cold sensory loss concentrates at T6-T9. The decline concentrates primarily at T4-T11. The lateral diffusion of block to the left side did not cross the posterior axillary line, and reached the posterior median line on the right. The area of cutaneous sensory loss was (172 ± 57) cm 2 , and the area of cutaneous sensory decline was (414 ± 143) cm 2. The duration of cutaneous sensory decline was (586 ± 28) minutes. Conclusion: Ultrasound-guided erector spine plane block with 20 mL of 0. 5% ropivacaine provided a widespread cutaneous sensory block in the posterior thorax, but did not reach the anterior chest, lateral chest, or abdominal walls. The range of the blockade suggested that the dorsal branch of spinal nerve was blocked.

Erector spinae plane block combined with general anaesthesia versus conventional general anaesthesia in lumbar spine surgery

“…Contrary to that, Zhang et al studied the range of area covered by ESP, they performed ESP in twelve cases and mapped the skin area blocked by ESP by cold sensory stimuli, the block did not extend to the lateral chest or anterior abdominal wall suggesting that only the dorsal branches of the spinal nerves but not the ventral branches were blocked [44].…”

The erector spinae plane block: the case of the elusive mechanism of action

“…Certains comptes rendus rapportent une préservation des nerfs cutanés antérieurs du thorax avec un bloc ESP, ce qui laisse penser que les rameaux ventraux ne sont pas uniformément bloqués. 5,6 D'autres études avec colorant ont montré une diffusion plus profonde à travers les foramens costotransverses et/ou dans l'espace paravertébral. 7,8 L'idée que le bloc ESP constitue une « porte d'entrée » pour l'espace paravertébral est certes séduisante.…”

“…Cependant, les études cliniques examinant les blocs ESP thoraciques observent d'importantes variations dans l'effet sur le dermatome d'une piqûre d'épingle ou de la sensation de froid, et certains blocs affichent même une épargne complète du tronc antérolatéral. 5,6 Il est donc surprenant de lire des comptes rendus rapportant l'efficacité du bloc ESP pour procurer un bloc chirurgical dense. Par exemple, Malawat et coll.…”

“…There have been some reports of the sparing of the anterior cutaneous nerves of the thorax with the ESP block, suggesting that ventral rami are not consistently blocked. 5,6 Other dye studies show deeper spread through the costotransverse foramina and/or into the paravertebral space. 7,8 The concept that the ESP block is a ''backdoor'' to the paravertebral space is certainly attractive.…”

“…Nevertheless, clinical studies involving a thoracic ESP block suggest widely variable patterns of dermatomal effect to pinprick or cold sensation, some of which exhibit complete sparing of the anterolateral trunk. 5,6 It is therefore surprising to read of the effectiveness of the ESP block in providing dense surgical blockade. For example, Malawat et al performed ESP blocks using 25 mL of 0.5% bupivacaine in 30 patients undergoing modified radical mastectomy and reported complete surgical anesthesia in every patient.…”