Neuromodulation: Technology at the Neural Interface Received: August 6, 2014
Revised: September 22, 2014
Accepted: September 29, 2014
(onlinelibrary.wiley.com) DOI: 10.1111/ner.12258
Intrathecal Pump: An Abrupt Intermittent Pump Failure John Riordan, MB, BCh, BAO, BMed Sc; Paul Murphy, MD Setting: Intrathecal baclofen is an established method of treating spasticity. However, this therapy is not without significant morbidity and mortality. The known morbidity associated with intrathecal pumps includes death, infection, and sepsis including central nervous system infection, accidental overdose, wrong drug administration as well as technical failures such as pump or battery failure, catheter migration or catheter breakage. Medtronic has issued a number of advisories, most recently in June 2013, regarding the safety of the Medtronic SynchroMed II intrathecal pumps. Patient: Sixty-four months post insertion of a SynchroMed II, model 8637; our patient was reviewed as a matter of urgency by our team, as he was complaining of worsening spasticity and pain. The device was interrogated and this indicated a motor stall at the time of interrogation. The interrogation also revealed that this was the third period of motor stall in the preceding three days. According to the patient, and consistent with our interrogation, the device had been alarming intermittently for the previous three days. Intervention: He was commenced on oral baclofen overnight, which gave some improvement to his symptoms. A replacement intrathecal pump was inserted the following day. This provided the patient with his usual level of relief. The product Engineering Department at Medtronic reviewed the original pump. Outcome: The patient’s new intrathecal pump has been functioning uneventfully since its replacement and he continues to receive good symptom relief from his new pump. Internal inspection of the pump by the Engineering Department at Medtronic revealed corrosion of the motor gearbox. Conclusion: Our unit continues to retain a high level of vigilance when dealing with potential complications of intrathecal pump therapy. Supplemental oral baclofen may have a role in this setting. Keywords: Baclofen, case report, intrathecal drug delivery, safety, withdrawal Conflict of Interest: The authors have no disclosures or conflicts to declare.
INTRODUCTION
MATERIALS AND METHODS
Intrathecal pump technology facilitates continuous central nervous system drug delivery. This allows for symptom relief while minimizing the systemic effects of delivering the same drug parentarally. Intrathecal baclofen is an established method of treating spasticity (1). However, this therapy is not without significant morbidity and mortality and every effort must be made to minimize complications. The known morbidity associated with intrathecal pumps includes death, infection, and sepsis including central nervous system infection, accidental overdose, wrong drug administration as well as technical failures such as pump or battery failure, catheter migration or catheter breakage (2). In the past number of years, Medtronic has issued a number of advisories most recently in June 2013, regarding the safety of the Medtronic SynchroMed II intrathecal pumps. A Food and Drug Administration recall notice issued in June 2013 issued a recall on the SynchroMed II, model 8637 describing potential electrical shorting (3). Medtronic data analysis quotes a 95.6% overall device survival probability for this model of intrathecal pump at five years (4).
The patient, a 37-year-old gentleman presented to this neurology service with worsening spasticity and pain. He had a prior history of childhood meningitis, complicated by contractures and spasticity of his back, head, and neck. For treatment of this he had a Medtronic SynchroMed II, model 8637-40, intrathecal pump inserted in March 2008, to facilitate intrathecal delivery of baclofen. Sixty-four months post pump insertion, at the request of our neurology service, the patient was reviewed as a matter of urgency
Department of Anaesthesia, Intensive Care and Pain Medicine, St. Vincent’s University Hospital, Dublin, Ireland For more information on author guidelines, an explanation of our peer review process, and conflict of interest informed consent policies, please go to http:// www.wiley.com/bw/submit.asp?ref=1094-7159&site=1
© 2014 International Neuromodulation Society
Neuromodulation 2015; 18: 433–435
433
www.neuromodulationjournal.com
Address correspondence to: John Riordan, MB, BCh, BAO, FCARCSI, FJFICMI, Department of Anaesthesia, Intensive Care and Pain Medicine, St. Vincent’s University Hospital, Elm Park, Dublin 4, Ireland. Email: [email protected]
RIORDAN & MURPHY by our service. The patient reported that the device had been alarming intermittently for the previous three days. Members of our team heard this at the time of interrogation. His device was interrogated, and this indicated a pump motor stall. The interrogation revealed a motor stall at day 10 post refill lasting for 9 hours 35 min, restarting spontaneously. A second stall occurred at day 11 post refill. This lasted 32 hours 15 min. The pump again restarted spontaneously at its usual rate. Prior to the interrogation the motor had stalled for a third time lasting 9 hours 3 min. The patient reported that he had heard the alarm occasionally in the previous number of days approximately during the times that the pump had stalled. The pump had functioned uneventfully for the preceding 64 months, and the previous refill of the pump, 13 days prior to presenting, had been uneventful. His daily dose of intrathecal baclofen was 2.3 mg/day, administered by simple continuous infusion at a concentration of 2 mg/mL. Therefore; we estimate that he was underdosed by 5.1 mg of intrathecal baclofen over the preceding three days. Reassuringly, he had experienced no seizures, his mental status remained normal, he was apyrexial and had a normal heart rate and blood pressure. The patient displayed no other features of a GABAergic mediated baclofen withdrawal syndrome other than worsening his spasticity (5). The patient was commenced on oral baclofen, 30 mg three times daily, which gave some improvement to his symptoms. The pump was explanted and a replacement intrathecal pump was inserted the following day. He was recommenced at his usual dose of intrathecal baclofen.
RESULTS This new pump provided the patient with his usual level of relief and he was discharged soon after, his new pump working well and with the same level of symptom control that the patient experienced prior to the series of stalls. The explanted intrathecal pump device was referred to the Medtronic Product Engineering service. The Medtronic Engineering Department reported that the pump motor compartment showed residue, corrosion and moisture present on the motor gear assembly, and that the corrosion of the motor gear box is related to the root cause of the reported motor stalls. The other aspects of the pump were within normal limits. The pump passed the Drug Dispense Accuracy Test (within 14.5% of desired drug delivery).
DISCUSSION
434
The pattern of intermediate stalling and restarting of an intrathecal pump, as seen in this case, is not one mentioned extensively in literature. We believe that this event should be considered a pump failure. We recommend that in the event of a similar presentation, the delivered drug should be administered by an alternative route, and the potentially defective pump be explanted and replaced with a new intrathecal pump. While enteral supplementation with baclofen does not remove the risk of a withdrawal syndrome it may have reduced the risk of this occurring and was associated with an improvement in the patient’s symptoms. Cyproheptadine also has been utilized in this clinical situation although neither approaches can be relied upon to prevent withdrawal syndromes. It also is reasonable to postulate that the patient may have been receiving some drug between stalls that this also may have helped prevent the development of withdrawal symptoms. www.neuromodulationjournal.com
The patient had a Medtronic SynchroMed II pump in situ at the time of the pump failure. The use of unlicensed medications has been associated with pump failure. At no time in the lifetime of this pump was any medication other than branded baclofen used for the patients pump. In a Food and Drug Administration class I recall notice issued in July 2011, on the SynchroMed II, model 8637, retrieval was not recommended in patients with this model in situ. As advised, we retain a high level of vigilance for the potential malfunction of these devices. Given the potential for morbidity with this patient population, as well as the potential for uncontrolled pain in other patients, our service endeavors to deal with any potential complication of intrathecal pump technology as a matter of the highest urgency. Medtronic has previously provided guidance for a similar clinical situation in the case of a battery failure. Patients are advised to attend our emergency department should concerns arise regarding implantable devices. As our service provides specialized pain services catering for patients throughout Ireland, some patients choose to attend their local general practitioner prior to making their journey. In this case, where the patient’s home is 100 km from our hospital, he chose to attend his general practitioner prior to arriving in the hospital. Intrathecal baclofen withdrawal syndrome is a GABAergic mediated withdrawal syndrome with serious and potentially fatal sequelae (5). A number of advisories have been issued relating to the functioning of Medtronic II pumps in the past 12 months. We are somewhat concerned regarding the long-term reliability of Medtronic pumps and that patients on long-term intrathecal opiates, benzodiazepines, clonidine as well as patients on longterm intrathecal baclofen are at risk of an acute life threatening withdrawal event.
CONCLUSION The patient’s new intrathecal pump has been functioning uneventfully since its replacement, and he continues to receive good symptom relief from his new pump. As mentioned the explanted pump was analyzed by the Engineering Department of Medtronic. The pump failure was reported to the Irish Medicines Board. Our unit continues to retain a high level of vigilance when dealing with potential complications of intrathecal pump therapy. Supplemental oral baclofen may have a role in this setting but cannot be relied upon to prevent baclofen withdrawal syndrome.
Authorship Statement Drs. Riordan and Murphy diagnosed, treated, and followed up with the patient. They also composed and read the final draft.
How to Cite this Article: Riordan J., Murphy P. 2015. Intrathecal Pump: An Abrupt Intermittent Pump Failure. Neuromodulation 2015; 18: 433–435
© 2014 International Neuromodulation Society
Neuromodulation 2015; 18: 433–435
VIGILANCE WITH INTRATHECAL TECHNOLOGY
REFERENCES 1. Penn RD, Savoy SM, Corcos D et al. Intrathecal baclofen for severe spinal spasticity. NEJM 1989;320:1517–1521. 2. Awaad Y, Rizk T, Siddiqui I, Roosen N, McIntosh K, Waines GM. Complications of intrathecal baclofen pump: prevention and cure. ISRN Neurol 2012; e-pub ahead of print. doi: 10.5402/2012/575168. 3. 3 June 2013. FDA Medtronic model 8637 SynchroMed II Implantable Infusion Pump recall letter. 4. 2012. Medtronic product performance report: data through July 31, 2012. http:// professional.medtronic.com/pt/neuro/idd/prod/synchromed-ii/performance-data/ index.htm#.UklK09KgrmQ 5. Coffey RJ, Edgar TS, Francisco GE et al. Abrupt withdrawal syndrome from intrathecal baclofen: recognition and management of a potentially life-threatening syndrome. Arch Phys Med Rehabil 2002;83:735–741.
435
www.neuromodulationjournal.com
© 2014 International Neuromodulation Society
Neuromodulation 2015; 18: 433–435
Revised: September 22, 2014
Accepted: September 29, 2014
(onlinelibrary.wiley.com) DOI: 10.1111/ner.12258
Intrathecal Pump: An Abrupt Intermittent Pump Failure John Riordan, MB, BCh, BAO, BMed Sc; Paul Murphy, MD Setting: Intrathecal baclofen is an established method of treating spasticity. However, this therapy is not without significant morbidity and mortality. The known morbidity associated with intrathecal pumps includes death, infection, and sepsis including central nervous system infection, accidental overdose, wrong drug administration as well as technical failures such as pump or battery failure, catheter migration or catheter breakage. Medtronic has issued a number of advisories, most recently in June 2013, regarding the safety of the Medtronic SynchroMed II intrathecal pumps. Patient: Sixty-four months post insertion of a SynchroMed II, model 8637; our patient was reviewed as a matter of urgency by our team, as he was complaining of worsening spasticity and pain. The device was interrogated and this indicated a motor stall at the time of interrogation. The interrogation also revealed that this was the third period of motor stall in the preceding three days. According to the patient, and consistent with our interrogation, the device had been alarming intermittently for the previous three days. Intervention: He was commenced on oral baclofen overnight, which gave some improvement to his symptoms. A replacement intrathecal pump was inserted the following day. This provided the patient with his usual level of relief. The product Engineering Department at Medtronic reviewed the original pump. Outcome: The patient’s new intrathecal pump has been functioning uneventfully since its replacement and he continues to receive good symptom relief from his new pump. Internal inspection of the pump by the Engineering Department at Medtronic revealed corrosion of the motor gearbox. Conclusion: Our unit continues to retain a high level of vigilance when dealing with potential complications of intrathecal pump therapy. Supplemental oral baclofen may have a role in this setting. Keywords: Baclofen, case report, intrathecal drug delivery, safety, withdrawal Conflict of Interest: The authors have no disclosures or conflicts to declare.
INTRODUCTION
MATERIALS AND METHODS
Intrathecal pump technology facilitates continuous central nervous system drug delivery. This allows for symptom relief while minimizing the systemic effects of delivering the same drug parentarally. Intrathecal baclofen is an established method of treating spasticity (1). However, this therapy is not without significant morbidity and mortality and every effort must be made to minimize complications. The known morbidity associated with intrathecal pumps includes death, infection, and sepsis including central nervous system infection, accidental overdose, wrong drug administration as well as technical failures such as pump or battery failure, catheter migration or catheter breakage (2). In the past number of years, Medtronic has issued a number of advisories most recently in June 2013, regarding the safety of the Medtronic SynchroMed II intrathecal pumps. A Food and Drug Administration recall notice issued in June 2013 issued a recall on the SynchroMed II, model 8637 describing potential electrical shorting (3). Medtronic data analysis quotes a 95.6% overall device survival probability for this model of intrathecal pump at five years (4).
The patient, a 37-year-old gentleman presented to this neurology service with worsening spasticity and pain. He had a prior history of childhood meningitis, complicated by contractures and spasticity of his back, head, and neck. For treatment of this he had a Medtronic SynchroMed II, model 8637-40, intrathecal pump inserted in March 2008, to facilitate intrathecal delivery of baclofen. Sixty-four months post pump insertion, at the request of our neurology service, the patient was reviewed as a matter of urgency
Department of Anaesthesia, Intensive Care and Pain Medicine, St. Vincent’s University Hospital, Dublin, Ireland For more information on author guidelines, an explanation of our peer review process, and conflict of interest informed consent policies, please go to http:// www.wiley.com/bw/submit.asp?ref=1094-7159&site=1
© 2014 International Neuromodulation Society
Neuromodulation 2015; 18: 433–435
433
www.neuromodulationjournal.com
Address correspondence to: John Riordan, MB, BCh, BAO, FCARCSI, FJFICMI, Department of Anaesthesia, Intensive Care and Pain Medicine, St. Vincent’s University Hospital, Elm Park, Dublin 4, Ireland. Email: [email protected]
RIORDAN & MURPHY by our service. The patient reported that the device had been alarming intermittently for the previous three days. Members of our team heard this at the time of interrogation. His device was interrogated, and this indicated a pump motor stall. The interrogation revealed a motor stall at day 10 post refill lasting for 9 hours 35 min, restarting spontaneously. A second stall occurred at day 11 post refill. This lasted 32 hours 15 min. The pump again restarted spontaneously at its usual rate. Prior to the interrogation the motor had stalled for a third time lasting 9 hours 3 min. The patient reported that he had heard the alarm occasionally in the previous number of days approximately during the times that the pump had stalled. The pump had functioned uneventfully for the preceding 64 months, and the previous refill of the pump, 13 days prior to presenting, had been uneventful. His daily dose of intrathecal baclofen was 2.3 mg/day, administered by simple continuous infusion at a concentration of 2 mg/mL. Therefore; we estimate that he was underdosed by 5.1 mg of intrathecal baclofen over the preceding three days. Reassuringly, he had experienced no seizures, his mental status remained normal, he was apyrexial and had a normal heart rate and blood pressure. The patient displayed no other features of a GABAergic mediated baclofen withdrawal syndrome other than worsening his spasticity (5). The patient was commenced on oral baclofen, 30 mg three times daily, which gave some improvement to his symptoms. The pump was explanted and a replacement intrathecal pump was inserted the following day. He was recommenced at his usual dose of intrathecal baclofen.
RESULTS This new pump provided the patient with his usual level of relief and he was discharged soon after, his new pump working well and with the same level of symptom control that the patient experienced prior to the series of stalls. The explanted intrathecal pump device was referred to the Medtronic Product Engineering service. The Medtronic Engineering Department reported that the pump motor compartment showed residue, corrosion and moisture present on the motor gear assembly, and that the corrosion of the motor gear box is related to the root cause of the reported motor stalls. The other aspects of the pump were within normal limits. The pump passed the Drug Dispense Accuracy Test (within 14.5% of desired drug delivery).
DISCUSSION
434
The pattern of intermediate stalling and restarting of an intrathecal pump, as seen in this case, is not one mentioned extensively in literature. We believe that this event should be considered a pump failure. We recommend that in the event of a similar presentation, the delivered drug should be administered by an alternative route, and the potentially defective pump be explanted and replaced with a new intrathecal pump. While enteral supplementation with baclofen does not remove the risk of a withdrawal syndrome it may have reduced the risk of this occurring and was associated with an improvement in the patient’s symptoms. Cyproheptadine also has been utilized in this clinical situation although neither approaches can be relied upon to prevent withdrawal syndromes. It also is reasonable to postulate that the patient may have been receiving some drug between stalls that this also may have helped prevent the development of withdrawal symptoms. www.neuromodulationjournal.com
The patient had a Medtronic SynchroMed II pump in situ at the time of the pump failure. The use of unlicensed medications has been associated with pump failure. At no time in the lifetime of this pump was any medication other than branded baclofen used for the patients pump. In a Food and Drug Administration class I recall notice issued in July 2011, on the SynchroMed II, model 8637, retrieval was not recommended in patients with this model in situ. As advised, we retain a high level of vigilance for the potential malfunction of these devices. Given the potential for morbidity with this patient population, as well as the potential for uncontrolled pain in other patients, our service endeavors to deal with any potential complication of intrathecal pump technology as a matter of the highest urgency. Medtronic has previously provided guidance for a similar clinical situation in the case of a battery failure. Patients are advised to attend our emergency department should concerns arise regarding implantable devices. As our service provides specialized pain services catering for patients throughout Ireland, some patients choose to attend their local general practitioner prior to making their journey. In this case, where the patient’s home is 100 km from our hospital, he chose to attend his general practitioner prior to arriving in the hospital. Intrathecal baclofen withdrawal syndrome is a GABAergic mediated withdrawal syndrome with serious and potentially fatal sequelae (5). A number of advisories have been issued relating to the functioning of Medtronic II pumps in the past 12 months. We are somewhat concerned regarding the long-term reliability of Medtronic pumps and that patients on long-term intrathecal opiates, benzodiazepines, clonidine as well as patients on longterm intrathecal baclofen are at risk of an acute life threatening withdrawal event.
CONCLUSION The patient’s new intrathecal pump has been functioning uneventfully since its replacement, and he continues to receive good symptom relief from his new pump. As mentioned the explanted pump was analyzed by the Engineering Department of Medtronic. The pump failure was reported to the Irish Medicines Board. Our unit continues to retain a high level of vigilance when dealing with potential complications of intrathecal pump therapy. Supplemental oral baclofen may have a role in this setting but cannot be relied upon to prevent baclofen withdrawal syndrome.
Authorship Statement Drs. Riordan and Murphy diagnosed, treated, and followed up with the patient. They also composed and read the final draft.
How to Cite this Article: Riordan J., Murphy P. 2015. Intrathecal Pump: An Abrupt Intermittent Pump Failure. Neuromodulation 2015; 18: 433–435
© 2014 International Neuromodulation Society
Neuromodulation 2015; 18: 433–435
VIGILANCE WITH INTRATHECAL TECHNOLOGY
REFERENCES 1. Penn RD, Savoy SM, Corcos D et al. Intrathecal baclofen for severe spinal spasticity. NEJM 1989;320:1517–1521. 2. Awaad Y, Rizk T, Siddiqui I, Roosen N, McIntosh K, Waines GM. Complications of intrathecal baclofen pump: prevention and cure. ISRN Neurol 2012; e-pub ahead of print. doi: 10.5402/2012/575168. 3. 3 June 2013. FDA Medtronic model 8637 SynchroMed II Implantable Infusion Pump recall letter. 4. 2012. Medtronic product performance report: data through July 31, 2012. http:// professional.medtronic.com/pt/neuro/idd/prod/synchromed-ii/performance-data/ index.htm#.UklK09KgrmQ 5. Coffey RJ, Edgar TS, Francisco GE et al. Abrupt withdrawal syndrome from intrathecal baclofen: recognition and management of a potentially life-threatening syndrome. Arch Phys Med Rehabil 2002;83:735–741.
435
www.neuromodulationjournal.com
© 2014 International Neuromodulation Society
Neuromodulation 2015; 18: 433–435
