Preface

Pain is a primary defensive mechanism existing in all living animals. As such, it helps to prevent or abort any harmful activity or stimulus, thereby stopping and avoiding further damage. But it can also be a source of immense trouble. Once the pain becomes chronic, it can lose this defensive aspect and transform itself into a new problem. Controlling chronic pain is the aim and purpose of many of our currently existing treatment strategies, significantly when the pain's original cause cannot be corrected any longer. How this chronic pain can be controlled is another source of concern.

People often take over-the-counter drugs, opioids, and other pain-management medications without in-depth knowledge of their long-term consequences. Examples include kidney damage that can be induced by NSAIDs or the strong addictive properties of opioids. As a result, our developed societies currently face an opioid epidemic, yet we often see many of these drugs being advertised on the TV as if they were a commodity to be used ad libitum.

Drugs have a significant advantage in that their use can be stopped if side effects appear, but chronic pain is not like other diseases. Once patients start with pain killers, particularly with opioids, all that can be expected is a progressive escalation in the dose and the drugs' analgesic power. In case of adverse effects, it is possible to change the drug but, in general, not to stop them altogether.

Over the years, many invasive procedures have been devised, aimed at controlling chronic pain. They can be broadly divided into reversible and disruptive. Generally, reversible treatments are preferred as no bridge is burnt, allowing other possibilities to be explored in case of failure. Among these reversible procedures, a wide array of neurostimulation options are available to control pain by inhibiting the chronic pain pathways. By modifying stimulation parameters or the location where stimulation is applied, different options can be explored. Ultimately, if there is no success, the equipment can always be disconnected and something else attempted.

In comparison, disruptive procedures are not reversible, but they are beneficial in treating some forms of chronic pain (i.e., DREZ procedure for brachial plexus avulsion pain), but these procedures are not devoid of problems and complications.

Unfortunately, at times, the economic cost of these procedures comes into play. For example, reversible stimulation procedures require very costly electronic equipment that is not always affordable, particularly in low-income countries. Conversely, disruptive procedures (i.e., cordotomy, DREZ, and zygapophyseal joint rhizotomy) are not that expensive and are available to a more significant range of economies. Unfortunately, not all pain-treating physicians have expertise with all of these techniques. Some are clinicians with a better understanding of drugs and their management, some are anesthetists that can perform certain invasive procedures (particularly neurostimulation), and others can fully perform disruptive operations. Today's pain clinics coordinate all of these players into a single treating group;

without them, patients must often go from one clinic to the next until they find a solution to their case at a price their pockets can afford.

This book attempts to illustrate some of the aforementioned disruptive procedures that can be of particular help to certain patients. It is also important to keep in mind that due to their very reasonable cost, these procedures can be utilized in almost any country, provided the treating physician masters them.

> **Vicente Vanaclocha** Professor, Department of Surgery, Division of Neurosurgery, University of Valencia, Spain

Dedication

*To the memory of my parents, my eternal support and inspiration*.

**Nieves Saiz-Sapena** University of Valencia, Spain
