|LETTER TO THE EDITOR
|Year : 2016 | Volume
| Issue : 2 | Page : 143-144
Is radiofrequency ablation of superior hypogastric plexus a correct approach to manage cancer pain or just a placebo?
Department of Anesthesia and Intensive Care, Al Sabah Hospital, Safat, Kuwait
|Date of Web Publication||18-Jul-2016|
Department of Anesthesia and Intensive Care, Al Sabah Hospital, Safat
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Aggarwal A. Is radiofrequency ablation of superior hypogastric plexus a correct approach to manage cancer pain or just a placebo?. Indian J Pain 2016;30:143-4
|How to cite this URL:|
Aggarwal A. Is radiofrequency ablation of superior hypogastric plexus a correct approach to manage cancer pain or just a placebo?. Indian J Pain [serial online] 2016 [cited 2020 May 26];30:143-4. Available from: http://www.indianjpain.org/text.asp?2016/30/2/143/186475
I read with great interest, the recently published article entitled "Radiofrequency ablation (RFA) of superior hypogastric plexus for the management of pelvic cancer pain."  Although I applaud the work, this case report raises some pertinent questions we need to ponder.
An understanding of the factors that affect RF heat lesion size and shape are critical for successful ablation of the target nerve or plexus. Lesion geometry determines the extent and likelihood of desired and undesired tissue damage, given the active tip's position and orientation in patient anatomy. RF heat lesion geometry depends reproducibly on electrode shape, tip diameter/gauge, tip length, tip temperature, and lesion time. ,,
- There is not mention of the characteristics of RF needle used whether straight or curved and length of un-insulated shaft
- How to confirm that needle is close to the plexus, that is, whether sensory or motor stimulation has been used and what is our goal when we are doing plexus ablation. Is dye spread close to target area enough to start doing conventional RFA. What was the impedance at the time of lesioning?
- According to principles of RF are two lesions of conventional RFA done at a single point, sufficient for thermal ablation of entire plexus?
Superior hypogastric plexus, a large plexus of nerves is located anterior to the L5 vertebra between the promontory of the sacrum and the bifurcation of the aorta in the retroperitoneal space. Further, the fibres separate and form right and left hypogastric nerves. 
A well-circumscribed lesion created by conventional RFA is shaped like a match head and using a needle 22-gauge, i.e. 0.71 mm in diameter and the usual lesion size is around 2-4 mm.  The heated lesion is maximal around the shaft of the needle and minimal ahead of the tip. The pattern of the electric field produced by RF is directly opposite.  Thus, the needle has to be placed parallel to the nerve for conventional RFA (thermo-coagulation) for the effective lesion.
To create a lesion of a larger area, Bipolar RFA is the chosen modality. Cosman et al. have mentioned in his article that Bipolar RFA between parallel cannulae produces a rounded brick-shaped lesion of comparable shape to three sequential monopolar lesions generated using the same cannulae and generator settings.  Also, dimensions grow most rapidly over the 1 st min, average lesion width is 11-20% larger at 2 min, and 23-32% larger at 3 min, compared with 1 min. 
Keeping all these points into consideration, I have failed to understand scientifically how to do precisely successful RFA of superior hypogastric plexus. As per the literature, it seems, at present, using even bipolar RFA it will be a herculean task to ablate efficiently the entire plexus.
| References|| |
Bharti N, Singla N, Batra Y. Radiofrequency ablation of superior hypogastric plexus for the management of pelvic cancer pain. Indian J Pain 2016;30:58.
Cosman ER Jr., Dolensky JR, Hoffman RA. Factors that affect radiofrequency heat lesion size. Pain Med 2014;15:2020-36.
Alberts WW, Wright EW Jr., Feinstein B, Von Bonin G. Experimental radiofrequency brain lesion size as a function of physical parameters. J Neurosurg 1966;25:421-3.
Gauci CA, Basia J. Manual of RF Techniques: A Practical Manual of Radiofrequency Procedures in Chronic Pain Management. 2 nd
ed. Meggen: Flivo Press Publication; 2004.
Waldman SD. Pain Management. 2 nd
ed. Philadelphia, PA: Elsevier Health Sciences Publication; 2011.