The Novel Costotransverse Foramen Block Technique: Distribution Characteristics of Injectate Compared with Erector Spinae Plane Block

Abstract

Background: The costotransverse foramen (CTF) is a space continuous with the paravertebral space. We hypothesized that injections passing through the CTF will result in a successful injectate spread to the paravertebral space.

Objectives: We investigated patterns of dye spread to assess characteristics of neural blockade following ultrasound-guided CTF and erector spinae plane (ESP) injection in an anatomic and clinical study.

Study design: Prospective cadaveric study, and case studies.

Setting: University hospital.

Methods: Six soft cadavers were studied. The boundaries of the CTF and the needle pathway of CTF injection were identified in the first cadaver. The CTF and ESP injections were performed on either the left or right sides of the T4 vertebral level in cadavers 2 to 6. Fifteen milliliters of 0.2% methylene blue was injected in each block, and the spread of dye was assessed by anatomic dissection. We also report 2 case studies of CTF and ESP blocks.

Results: Cadaver studies of CTF injection demonstrate that with injection to the inferior aspect of the base of the transverse process, the dye mainly passes anteriorly through the CTF into the paravertebral space, with minimal track-back to the deep back muscles. Consistent sensory blockade was achieved in 2 case studies. With the ESP injection, the spread of dye was observed cephalocaudad to the fascia of the erector spinae muscle, with no dye spreading within the paravertebral space in all cadavers.

Limitations: Prospective case series.

Conclusions: CTF block was consistently associated with a mainly anterior spread of injectate into the paravertebral space that involved the thoracic spinal nerves, and minimal posterior spread of injectate to the deep back muscles.

Key words: Thoracic vertebrae, rib cage, paraspinal muscle, nerve block, joints.