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Do We Need New Guidelines for Interventional Pain Procedures in Patients on Anticoagulants?

In this issue of Regional Anesthesia and Pain Medicine, Giberson et al 1 and Buvanendran and Young report the occurrence of spinal epidural hematomas in patients whose only apparent risk factor for the hematoma was their use of aspirin. These 3 cases are notable because the current guidelines from the American Society of Regional Anesthesia and Pain Medicine (ASRA) for the placement of epidural and spinal catheters do not recommend cessation of these antiplatelet agents for epidural procedures; nor do the guidelines differentiate between the often disparate procedures for interventional pain and those performed for perioperative anesthesia/analgesia. There are several reasons why the issue of antiplatelet agents and possibly other anticoagulants for some chronic pain procedures (eg, percutaneous spinal cord stimulation lead placement) may need to be rethought. First, the procedure for spinal cord stimulation lead placement requires the use of very large bore 14-gauge needles with a long ramped bevel to enhance directional control. These needles are placed at shallow angles into the interlaminar opening and, quite commonly, there is a need to place 2 or more needles and sometimes even to replace the needles. This is done in the presence of fibrous adhesions, plica mediana dorsalis, scar, or spinal canal stenosis/anatomical narrowing that prevents passage of the lead in the anatomical midline from the point of epidural space entry. Second, the leads are stiff, styletted cylindrical objects with multiple electrode contacts (up to 16), and may require repeated manipulation to achieve optimal locations for stimulation paresthesias that are analgesic. As noted, this process can entail multiple changes of stylets, repeated retraction, and steering of the leads into different areas of the epidural space. When leads are retracted, as noted by Giberson and colleagues, there may be a risk for “snagging” the edge of the lead, causing a sharp edge. Third, it is not rare for the lead to move laterally within the epidural space or even to enter the anterior epidural space despite apparent midline placement during fluoroscopy in the anteroposterior plane. To some extent, this risk can be reduced by alternating biplanar imaging, particularly using the lateral view. It may be that the lateral or anterior areas of the epidural space, where veins may be more prevalent, are at greater risk for vascular trespass. In some cases, however, the targeted area may be the lateral “gutter” of the epidural space. Fourth, technology is changing as quickly as the number of new pharmaceutical agents for anticoagulation. There are other types of percutaneous leads that are more paddle-shaped being placed through introducers as well as ongoing trials of novel dorsal root ganglion leads, which are designed to intentionally exit the neural foramen with unknown cumulative risks of bleeding/vascular trespass. Finally, the safety of placing chronic long-term stimulation devices in patients who will need to resume anticoagulation remains largely uncertain. Worries about lead migration causing a rebleed remain. In the 2 cases described by Giberson and colleagues, the hematomas seemed to be related to the removal of the spinal cord stimulator (SCS) leads. One patient took an aspirin-containing medication the morning the leads were pulled out. It is possible that this unique patient developed a spinal hematoma the first time he complained of back pain and transient paraplegia the day after the electrodes were placed. Unfortunately, no imaging was performed in the emergency department to confirm or rule out this possibility. The other patient stopped aspirin and “other nonsteroidal anti-inflammatory drugs” a week before the trial. The leads were removed 4 days later, or 11 days after the antiplatelet medications were stopped. Bleeding after removal of catheters is known; the reasons include trauma to vascular structures during manipulation and/or dislodgement of a clot or in the setting of full anticoagulation. In fact, Vandermeulen et al noted that almost half of the cases of reported spinal hematoma occurred immediately after removal of the catheter, leading to the ASRA recommendations that the same guidelines should apply to both placement and removal