PAIN MEDICINE: Case Report
Neuraxial catheters may be placed to provide intraoperative anesthesia, postoperative analgesia, or interventional pain management. Most catheters used for perioperative regional techniques are composed of biologically inert plastic. The incidence of catheter breakage, resulting in a retained catheter fragment, is unknown. Likewise, the decision to remove or leave indwelling sequestered catheter sections remains controversial. Texts have increasingly recommended that catheters sheared or broken off in the epidural space not be removed surgically unless the catheter fragment is in the subcutaneous tissues, where it may serve as a wick for infection into the epidural space (1,2). Typically, the patient is informed of the catheter fragment, and no surgical intervention is recommended unless the patient develops symptoms (3,4). Fragmented intrathecal catheters have been managed similarly without complication (5).
The Racz® catheter (Epimed International, Inc., Johnstown, NY) differs in application and composition from standard neuraxial catheters. The catheter is constructed of a continuous stainless-steel coil with a dual fluoropolymer coating. Tensile strength is further increased by the presence of an intralumen stainless-steel ribbon. Nonetheless, Racz® catheter breakage and unraveling have been reported (6–8). Sequestration of such a catheter tip may have clinical implications. This ferromagnetic catheter may interact with the magnetic field during subsequent magnetic resonance imaging (MRI). We report a case in which a patient with a retained Racz® catheter fragment underwent an uneventful MRI study. The catheter fragment was incidentally removed during lumbar laminectomy.
The patient was a 51-yr-old man with a 9-yr history of low back pain. Lumbar hemilaminectomies were performed 4 and 7 yr after the initial injury. He reported relief of symptoms for 2 yr after the second surgery, when he began to experience worsening of moderate lower back pain. He was evaluated by an outside neurosurgeon, who believed that the patient was not a surgical candidate. The patient was referred to a pain clinic, where MRI suggested epidural scarring. The patient was believed to be a good candidate for a “caudal with an epidurogram using a Racz® catheter.” During the procedure, the Racz® catheter was inserted and manipulated toward the right L5 nerve root under fluoroscopic observation. Lysis of adhesions was attempted, but there was considerable resistance to manipulation of the Racz® catheter, and during withdrawal a significant portion sheared off and remained in the sacral hiatus. The patient’s pain and neurologic status were unchanged. Surgical removal of the retained catheter fragment was not advised. The patient did not receive counseling regarding the effect of the retained catheter fragment on future MRI studies.
The patient presented to this medical center 3 mo later for evaluation of his recurrent lumbar radiculopathy. As part of the evaluation, a lumbar series of radiographs and an MRI examination were ordered. The lumbar films demonstrated hypertrophic changes and the presence of an opaque catheter fragment in the sacral canal. The MRI was compromised in the vicinity of the L5-S1 nerve root because of a metallic artifact (Fig. 1), and the neurosurgeon thus requested a computerized tomography myelogram, which demonstrated a nonfilling defect of the right S1 nerve root. Electromyography demonstrated an acutely worsened right S1 radiculopathy, and surgical correction was advised and performed. During the partial hemilaminectomy at L5-S1 on the right, the catheter fragment was visualized in the epidural space just to the left of the midline. The 8-cm Racz® catheter fragment was extracted (Fig. 2), and the surgery proceeded uneventfully. The patient subsequently recovered without complications and reported relief of pain symptoms.
The Racz® catheter was introduced in 1981 (9) as an alternative epidural catheter for providing anesthesia or analgesia. Initial reports of catheter breakage and unraveling (6,7) led to improvements in catheter strength (10). The catheter is used exclusively in interventional pain management. Awareness of the character and number of catheter manipulations required during epidural neuroplasty suggests a mechanism of catheter breakage. If a caudal approach is used, epidural needle position within the sacral canal is fluoroscopically verified and an epidurogram is performed. If a “filling defect” consistent with the patient’s pain is identified, the catheter is directed toward this site. Multiple passes and adjustments may be required to successfully position the catheter at the scarred area. Lysis of adhesions is promoted by the injection of saline (with or without hyaluronidase). The catheter is secured and left in place for three days. On the second and third days, the catheter is injected once daily with local anesthetic, followed by hypertonic saline (11). This patient had been scheduled for a similar procedure, but the catheter broke during the initial catheter placement.
Although the patient was aware of the retained catheter fragment, he had not been advised of potential complications relating to the retained segment. Thus he denied, during his pre-MRI screening, the presence of metallic objects that could result in bodily harm or degrade image quality. Consequently, the neurosurgeon and radiologist assumed that the fragment was that of a standard epidural catheter. The observed ferromagnetic image degradation proved this assumption to be incorrect. MRI in patients with incorporated ferromagnetic objects can result in object movement, dislodgement, or thermal injury (12,13). No change in the patient’s neurologic status was noted, however, after his MRI. It is important to note that the manufacturers have recently placed a warning on the Racz® catheter packaging stating that patients with retained catheter fragments should not undergo MRI studies. This is of potential significance because MRI has become the predominant imaging modality for assessment of back pain and radiculopathy.
The incidence of Racz® catheter breakage is unknown. Peer-reviewed publications regarding this catheter consist of letters to the editor (6,7,14,15) and case reports (8) and involve catheter-related complications. A leading authority writes (11), “In our practice, catheter shearing does seem to occur every time we have a new group of pain fellows,” suggesting that sheared catheters are not uncommon.
A Food and Drug Administration (FDA) Web site (http://http://www.fda.gov/cdrh/maude.html) contains 22 Racz® catheter-shearing reports. MRI was used to characterize the retained fragment in two cases. In seven patients, the catheter remnant was surgically removed. Because the MedWatch system uses voluntary reporting of adverse events by physicians and other health care professionals, it is very likely that the actual frequency of Racz® catheter shearing and breakage is more frequent. For example, a survey of physicians estimated that only 5% of adverse events were reported to the FDA (16).
The decision to surgically remove broken neuraxial catheters or manage the patient conservatively is controversial. Current practice, based on ease of retrieval, is to observe the patient if a standard nonferromagnetic catheter fractures in the lumbar region (1,2) but to intervene if the catheter was placed caudally (1). Conversely, surgical removal of a retained Racz® catheter is strongly recommended (11), but the rationale for catheter removal is not provided. There is potential for neurologic and/or infectious complications with any foreign body. However, the presence of a Racz® catheter fragment may present additional risk. Although our patient underwent MRI uneventfully, it cannot be assumed that MRI is safe in patients with a retained Racz® catheter segment, and the packaging advises otherwise. Safety issues aside, a retained Racz® catheter fragment can result in MRI image degradation. In this case, this resulted in a wasted MRI scan and required an alternative imaging method to obtain pertinent anatomical information.
In summary, we present a case in which a patient with a retained Racz® catheter segment underwent MRI without neurologic worsening, although the images were degraded and required additional diagnostic imaging studies. Increased awareness of the Racz® catheter construction and vigilance in pre-MRI screening are necessary to decrease the possibility of catheter-magnetic field interactions and to avoid the cost of additional imaging. More information is needed to determine whether removal of retained Racz® catheter fragments is necessary.
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© 2003 International Anesthesia Research Society
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