A Contemporary Medicolegal Analysis of Implanted Devices for Chronic Pain Management : Anesthesia & Analgesia

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Chronic Pain Medicine: Original Clinical Research Report

A Contemporary Medicolegal Analysis of Implanted Devices for Chronic Pain Management

Abrecht, Christopher R. MD*; Greenberg, Penny RN, MS; Song, Ellen; Urman, Richard D. MD, MBA*; Rathmell, James P. MD*

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Anesthesia & Analgesia 124(4):p 1304-1310, April 2017. | DOI: 10.1213/ANE.0000000000001702
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Chronic pain is a large and growing problem in the United States, estimated to cost more health care dollars each year in the United States than heart disease, cancer, or diabetes.1 An estimated 100 million Americans are affected.2

Among the modalities available for the treatment of intractable pain are implanted devices such as intrathecal drug delivery systems (IDDS) and spinal cord stimulators (SCS). Clinical studies have indicated that among the most common indications for IDDS are failed back surgery syndrome, spasticity, degenerative joint disease, and malignant pain.3 For SCS, the indications include complex regional pain syndrome, failed back surgery syndrome, peripheral vascular disease, visceral pain, and peripheral neuropathy.4 Clinical studies, most of which are retrospective and observational in nature, have also reported on the common complications associated with these devices. Among IDDS, for instance, catheter-related complications such as catheter fracture, dislodgement, or migration are more common than deep infections requiring device explantation.5 The rarest of complications, which are often associated with significant morbidity, remain challenging to study. Intrathecal granuloma, for example, was estimated to occur in patients with intrathecal infusion devices at an incidence of 0.49%.6 Perioperative outcomes have also been reported.6a

Analyses of closed malpractice claims allow the study of rare but serious complications and, by raising awareness of such complications, are thought to have improved patient safety.7 Many such studies have been performed on anesthesia subspecialties in the United States8–10 as well as internationally.11,12 Closed claims analyses in the United States have already focused on injury and liability associated with chronic pain management, but have not focused on more recent cases from the last decade.13,14

The Controlled Risk Insurance Company (CRICO) is a malpractice insurance carrier. Its CRICO Strategies Comparative Benchmarking System (CBS) is an extensive repository of medical malpractice cases that also includes cases from other malpractice carriers and allows for the standardized study of a large group of claims. The claims presented in this analysis were drawn from a 5-year period from 2009 to 2013. By drawing from an array of malpractice carriers and from a recent timeframe, this analysis may represent more closely than other medicolegal studies the contemporary practice of pain medicine involving implanted devices.


CRICO was founded as a captive professional liability insurer for hospitals in the Harvard medical community. The CRICO Strategies CBS, in turn, is a database containing more than 400,000 malpractice claims from Harvard affiliate institutions and more than 400 academic and community institutions from across the country, representing approximately 30% of malpractice cases in the United States. CBS is used by CRICO’s Risk Management Foundation and other insurers across the country to study patient and provider risk using a standardized methodology.

The severity scale field used in the CBS database is that of the National Association of Insurance Commissioners,15 a scale from 0 to 9 whereby 0 corresponds to no injury and 9 corresponds to death. For our analysis, “high-severity” cases were 6 to 9 and represented death and other permanent major outcomes. “Medium-severity” cases were 3 to 5 and represented temporary major and permanent minor outcomes. “Low-severity” cases were 0 to 2 and represented temporary minor outcomes.

We queried the CRICO Strategies CBS database for the period January 1, 2009 to December 31, 2013, for cases in which pain medicine was the primary service. Pain medicine represented approximately 1% of cases from this period, whereas anesthesiology represented 5% of cases. Cases representing acute pain management were identified by manual inspection of the case narrative summaries and were removed from this analysis. Of the remaining chronic pain medicine cases, those representing outpatient pain procedures unrelated to implantable devices (eg, epidural steroid injections) and medication management were then removed from our analysis. The remaining 28 pain medicine cases involved IDDS and SCS. The average total incurred per case by primary responsible service was queried from the CBS database in August 2014. These payment amounts include the indemnity ultimately paid to the patient as well as the cost of legal fees.

The variables provided by case included the following: claimant age, claimant gender, indemnity paid to the patient, total incurred by the insurance carrier, location of injuring event (eg, physician clinic, ambulatory surgery center), National Association of Insurance Commissioners score, current procedural terminology code, International Classification of Diseases, 9th Revision code for the injury, and the CRICO-coded field for the injury (eg, infection, hematoma). Also provided was a detailed narrative summary of the case prepared by CRICO, including the information from the medical files, claims files, depositions, and the testimony of expert witnesses for the defense and the prosecution and how the cases settled (eg, closed to a statute of limitations versus dismissed with prejudice). The original case documents were examined when additional details were sought.

Contributing factors determined to have led to the alleged damaging event were another variable in the CRICO Strategies CBS database. More than 1 of these contributing factor subcategories could be listed for a given claim. For example, a case coded as having the technical skill category could have multiple subcategories including inexperience with the procedure, incorrect body position, or a retained foreign body. Similarly, the clinical judgment category included such descriptors as a narrow differential diagnosis focused only on the patient’s chronic issues, inadequate assessment before discharge, failure to respond to the patient’s concerns, or selection of an inappropriate surgical intervention. Communication subcategories included the inadequate consent and poor physician–patient rapport; documentation subcategories included deficits in documented consent and clinical findings. Furthermore, a given claim could be identified as having multiple contributing factor categories (eg, deficits in technical skill as well as in supervision of staff).

The contributing factors and other coded variables were applied by clinical taxonomy specialists who are registered nurses overseen by a taxonomy governance committee of physicians, lawyers, and other analysts. The decision, for instance, to apply a technical skill-contributing factor is based on the taxonomy specialist’s review of the medical records, the testimony of the expert witnesses, and the guidelines of the proprietary taxonomy manual. Similarly, the chronic pain diagnosis listed as prompting implantation was selected by the clinical taxonomy specialist, not the implanting physician. Regular audits of the coding process performed by the taxonomy governance committee ensure consistency and accuracy of the contributing factors and other coded fields.


Table 1.:
Patient Demographics, Outcome Severity, and Financial Impact of IDDS / SCS Claims
Table 2.:
Total Amount Incurred in Closed Claim, by Primary Service

The average total incurred for pain medicine claims was $166,028 higher than the averages for general surgery, anesthesiology, and orthopedics. Table 1 lists the incurred amounts by primary service. IDDS represented 17 of the closed claims; SCS represented 11 of the closed claims. The patient demographics and claim characteristics are listed in Table 2.

Patient Conditions Prompting Device Implantation

Figure 1.:
Chronic pain diagnosis for IDDS / SCS implantation. A, Chronic pain diagnosis for IDDS implantation. B, Chronic pain diagnosis for SCS implantation. Degenerative joint disease, with lumbar radiculopathy (DJD, with L radiculopathy), degenerative joint disease, with cervical radiculopathy (DJD, with C radiculopathy), cerebrovascular infarct-triggered central pain (CVA-triggered central pain), not available (N/A). IDDS indicates intrathecal drug delivery systems; SCS, spinal cord stimulators.

The chronic pain diagnoses for which devices were implanted are listed in Figure 1. Nonmalignant, nonspastic pain (eg, failed back surgery syndrome, degenerative joint disease with lumbar, or cervical radiculopathy) represented the overwhelming majority of cases. Malignant pain represented only 1 IDDS case. Other diagnoses cited for IDDS implantation included complex regional pain syndrome and postsurgical neuropathic pain.

Damaging Events

The alleged damaging events prompting patient injury are listed in Figure 2. Pump refill errors were among the most common damaging events. These alleged damaging events included a relatively benign case wherein an intentional IDDS dose increase was judged to be within the standard of care resulted in patient sedation. Other cases included accidental subcutaneous injection of 100 µg/mL sufentanil by a registered nurse in an obese patient with abdominal scar tissue, an accidental 6-fold intrathecal medication dose increase performed by a medical assistant, and an accidental 20-fold dose increase performed by a physician.

Figure 2.:
Alleged damaging events for IDDS / SCS claims. A, Alleged damaging event for IDDS claims. B, Alleged damaging events for SCS claims. Failure to monitor for aberrant drug behavior (ADB).

Intraoperative nerve damage was another common alleged damaging event. One of these cases involved an uneventful placement of a SCS under monitored anesthesia care, after which the patient developed permanent left lower extremity weakness, determined later by computed tomographic myelogram and a neurology consultant to be Brown Sequard syndrome likely because of traumatic insertion of the lead. Other cases involved transient weakness or transient worsening pain after uneventful SCS trials with no imaging supporting any neuraxial damage and which were dismissed.

Postoperative infection damaging events included soft tissue and epidural abscess formation related most often to the infection surrounding a device component. In 1 case, a patient who went swimming against medical advice after IDDS implantation developed pseudomonas meningitis.

Intrathecal granuloma formation was marked in all cases by a decreased analgesic effect despite an increased dose of intrathecal medications. Diagnostic interventions were delayed until after neurologic deficits had developed. Involved agents included intrathecally delivered morphine and, in 1 case, methadone.


The outcomes are detailed in Figure 3. High-severity outcomes consisted of nerve damage and death. These nerve damage outcomes ranged from IT granuloma-related persistent bilateral lower extremity weakness to IT granuloma-related paraplegia and epidural abscess-related quadriplegia requiring tracheostomy, enteric feeding tube, and placement in a long-term care facility. The 2 cases of death were attributed to pulmonary emboli.

Figure 3.:
Outcomes for IDDS / SCS claims, by outcome severity. A, High-severity outcomes for IDDS claims. B, High severity-outcomes for SCS claims. C, Medium-severity outcomes for IDDS claims. D, Medium-severity outcomes for SCS claims. IDDS indicates intrathecal drug delivery systems; SCS, spinal cord stimulators.

Medium-severity outcomes included drug reactions, all from pump refill errors and ranged from somnolence to respiratory arrest requiring intensive care unit admission and naloxone infusion. Other medium-severity outcomes included the need for reoperation, most commonly because of the retained device component or infection. Complaints of no improvement or worsening of symptoms (eg, pain, urinary incontinence) were also a common outcome.

Contributing Factors

Table 3.:
IDDS and SCS Contributing Factors, as Coded by CRICO

The CRICO Strategies CBS-coded contributing factors are listed in Table 3. One case had no factors, 5 cases had 1 factor, 11 cases had 2 factors, 5 cases had 3 factors, 4 cases had 4 factors, 1 case had 5 factors, and 1 case had 6 factors.


Pump refill errors and nerve damage, whether from intraoperative injury, infection, or intrathecal granuloma formation, were the foremost cause of patient injury in this series. The pump refill claims included inadvertent subcutaneous injection of medication and programming errors, in multiple instances by providers without substantial training in performing this procedure. These findings build on the previous reports of pocket fills and programming errors as the causes of injury.16,17 The nerve damage claims relating to intraoperative injury and the development of infection also reflect the published reports of these known complications.18,19 Furthermore, the intrathecal granuloma claims, in this series often involving a delay in diagnosis, reflect device company and peer-reviewed reports of this complication.20,21 New findings from this case series include the observation that the mean payment for chronic pain claims ranks above the mean payment for operating room anesthesiologists and near that of many other surgical specialties. The contributing factors analysis provided by CRICO Strategies also offers a novel, standardized method for commenting on risk.

The lessons gleaned from this case series echo suggestions from professional society guidelines, the American Society of Anesthesiologists Closed Claims Project, and other groups. Intrathecal drug delivery system refills, performed relatively frequently but with a small margin of error and a high risk of patient harm, must be given their due attention. Clinicians performing refills must be properly trained, and patients should be made aware of the signs of complications. As consensus guidelines have already suggested, a device refill template should be available during pump refills and fluoroscopy or ultrasound considered in technically challenging cases.22 If used, these diagnostic modalities should also be documented.

This case series also highlights the American Society of Anesthesiologists Closed Claims Project’s message that claims in pain management are likely increasing in number and severity.23 Nerve damage, for instance, has been shown in a previous report on neuraxial procedure claims to be a permanent, disabling outcome related to needle trauma, hematoma, and other injuries such as abscess or spinal cord infarct from intra-arterial injection.24 Therefore, providers should not only be aware of the possibility of these complications—and inform their patients accordingly during the consent process—but also minimize provider-derived risk by undergoing adequate procedural training in pain medicine. Furthermore, both this case series and the American Society of Anesthesiologists Closed Claims Project have shown that malpractice claims in pain medicine are associated not only with the provider, but also with patient risk factors.14,25 Mitigation of patient-related risk may be achieved through consistent, clear communication and expectation setting between the provider and the patient. Proper patient selection, including a thorough psychologic assessment, is also essential for mitigating risk and has long been supported in the pain management literature and detailed in society guidelines.26 Continued vigilance for aberrant drug behaviors is also essential for patients with implanted devices. Finally, pain medicine physicians must be aware that decreasing pain relief, new back pain, and neurologic deficits could herald an intrathecal granuloma in a patient with an intrathecal drug delivery system. The diagnostic test of choice for this condition is magnetic resonance imaging; evidence of neural compression should prompt a neurosurgical consultation.27 Computed tomography with myelography, looking for a filling defect within the thecal sac, is another acceptable modality to evaluate for intrathecal granuloma.28

Limitations of this study include the well-documented limitations of other closed claim analyses.29 First, a closed claims analysis provides only a partial numerator; it does not capture all of the complications because not all complications end in malpractice insurance claims. It also does not provide a denominator and therefore cannot estimate the incidence of complications. Second, it is biased toward more severe complications, in part because these are more likely to result in significant monetary compensation. Third, as a retrospective analysis without a control, it cannot establish a cause–effect relationship. Fourth, the data are not randomized and may not apply, for example, to a practitioner in a different geographic region treating a different patient population. Despite these limitations, closed claims analysis allows the study of a large number of rare but frequently severe complications. An additional limitation of this study, not shared with other closed claims analyses, is that the contributing factor criteria and selection of other coded fields are proprietary to CRICO and therefore cannot be independently verified by another entity.


Implanted devices used for pain management involve a significant risk of morbidity and mortality. Proper education of providers and patients is essential. Providers must acquire the technical skills required for implantation and refilling of these devices and the clinical skills required for the identification and management of complications such as intrathecal granuloma formation. Proper patient selection is crucial as is clear communication between the provider and the patient about the possibility of complications.


Name: Christopher R. Abrecht, MD.

Contribution: This author helped collect and analyze the data, and write and edit the manuscript.

Conflicts of Interest:None.

Name: Penny Greenberg, RN, MS.

Contribution: This author helped collect and analyze the data, and edit the manuscript.

Conflicts of Interest:None.

Name: Ellen Song.

Contribution: This author helped collect and analyze the data, and edit the manuscript.

Conflicts of Interest:None.

Name: Richard D. Urman, MD, MBA.

Contribution: This author helped analyze the data, and edit the manuscript.

Conflicts of Interest:Richard D. Urman has received funding from Medtronic for an unrelated study.

Name: James P. Rathmell, MD.

Contribution: This author helped review the data, and edit the manuscript.

Conflicts of Interest:None.

This manuscript was handled by: Honorio T. Benzon, MD.

Acting EIC on final acceptance:Thomas R. Vetter, MD, MPH.


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