• Cancer Pain
• CHRONIC PAIN
• Multimodal Imaging
• Ultrasonography

We read with great interest the letter to the editor by Hernández-Porras et al entitled ‘Phenol Spread in Erector Spinae Plane Block for Cancer Pain’. In the letter, the authors describe a case where an erector spinae plane (ESP) block with phenol 6% was used for the treatment of refractory, thoracic, and chest wall pain in the setting of metastatic lesions to the pleura.1 This is one of the first reports where a neurolytical ESP was successfully used for the treatment of refractory, thoracic cancer-related pain. We commend the authors for their thought-provoking report.

Originally described for the treatment of thoracic neuropathic pain, the scope of applications of the ESP block has since expanded to encompass numerous perioperative and chronic pain settings.2 Nonetheless, use of a neurolytical ESP block raises several concerns. Recently, Schwartzmann et al demonstrated, in an MRI study of patients receiving an ESP block, that the injectate consistently reached the paravertebral and intercostal spaces, and in some cases the epidural space.3 This potential for epidural spread is particularly concerning in a neurolytical blockade, where rare but potentially catastrophic consequences may occur. In the past, epidural neurolysis with alcohol and phenol has been linked to complications such as paraplegia and urinary incontinence.4 5 These findings encouraged us to share a technical note based on our experience at the Division of Pain Medicine at a tertiary academic medical center affiliated with the University of Barcelona.

Hernández-Porras et al 1 used intraoperative CT to assess for contrast spread prior and during injection of the neurolytical agent.1 However, cost and limitations in availability of intraoperative CT may make it prohibitive for widespread use in this setting. In our Interventional Cancer Pain Program, we use intraoperative fluoroscopy as an alternative imaging modality to assess for contrast spread prior to and intermittently during injection of the neurolytical agent.

We attach an echogenic sharp needle (50/80 mm Echogenic Sonoplex II block needle; PAJUNK, Geisingen, Germany) to a double syringe montage using a Luer lock connector, one syringe containing 5 mL of non-ionic, water-soluble, iohexol contrast dye (Omnipaque 300; GE Healthcare, Chicago, Illinois, USA), and the other containing 10 mL of phenol 6% mixed with 5 mL of the aformentioned contrast dye (figure 1). This allows us to swap between injecting contrast and phenol while minimizing the risk of inadvertently moving the needle tip after achieving adequate contrast spread. After hydrodissection of the ESP under ultrasound (US) guidance with 2–3 mL of sterile saline solution, we administer 5 mL of contrast dye under continuous, combined US and fluoroscopy-guidance in the lateral view. Following a wait period of 2 min, we obtain a single lateral fluoroscopy image to exclude unequivocal epidural spread of contrast. We then administer three 5 mL boluses of phenol 6% mixed with contrast, each followed by another 2 min wait period. In the past, patients submitted to epidural phenol neurolysis have been found to accurately tell epidural spread of phenol within 30–60 s due to the onset of local discomfort, itching, and burning.5 After each 2 min wait period, another single lateral fluoroscopy image is obtained, once again to exclude the unequivocal pattern of epidural spread of the neurolytical agent. In total, we obtain four fluoroscopy images in the lateral view per procedure (one after contrast dye injection and one after each bolus of the therapeutic solution).

• Download figure
• Open in new tab
• Download powerpoint

Figure 1

Neurolytical erector spinae plane block with phenol 6%, showing the double syringe montage with a Luer lock system (left side) and the ultrasound scan at the level of the transverse process of the fifth thoracic vertebra, showing adequate cephalo-caudad injectate spread (right side). D, distal; P, proximal; T5, transverse process of the fifth thoracic vertebra.

Our experience is in keeping with the report by Hernández-Porras et al, suggesting that under image guidance this procedure can be performed with minimal risk.1 Furthermore, in settings where CT is not available for intraoperative use, fluoroscopy might be an adequate alternative.