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Interv Pain Med
Interv Pain Med
Interventional Pain Medicine
2772-5944
Elsevier

S2772-5944(24)00002-5
10.1016/j.inpm.2024.100384
100384
Case Report
Catheter dysfunction in long-term intrathecal baclofen pump users and when to evaluate integrity: A case series
Dean Kaylie P. Dean.kaylie@mayo.edu
a∗
Beck Lisa A. a
Mauck William D. b
a Mayo Clinic Department of Physical Medicine & Rehabilitation, United States
b Mayo Clinic Department of Pain Medicine, United States
∗ Corresponding author. Dean.kaylie@mayo.edu
17 1 2024
3 2024
17 1 2024
3 1 10038417 8 2023
29 12 2023
29 12 2023
© 2024 The Authors
2024
https://creativecommons.org/licenses/by-nc-nd/4.0/ This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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pmc1 Introduction

Intrathecal baclofen can be a life changing therapy for those with otherwise intractable spasticity. However, when intrathecal baclofen administration is interrupted, life-threatening withdrawal can occur. Inasmuch, an understanding of the delivery system is crucial. The intrathecal drug delivery system (IDDS) consists of a pump/reservoir component and a catheter component. The pumps have an approximate battery life of 7 years requiring a surgical exchange when expired. The catheter component has no such expiration yet and contributed to 83 % of the product performance events according to a 2016 Implantable Systems Performance Registry [1]. In 2012, Medtronic introduced new coated catheters (catheter models 8780 and 8781) enhanced with a braided polymer design to increase catheter “strength and durability” compared to the older, traditional silicone catheters (catheter models 8709, 8709 S C, 8711, 8731, 8731 S C, 8703 W). The 2022 Medtronic Product Performance Report demonstrated that only 69.4 % of the product performance events were from the catheters alone—a reduction, but still quite significant. The 3 most common catheter-related events were break, occlusion, and dislodgment from the pump in the old catheters and kink, occlusion, and dislodgement in the new catheters. Of note, catheter break was rare in the new catheters compared with older catheters (5 % vs 19 %) [2].

A common means of identifying catheter dysfunction are catheter access port (CAP) myelography (intrathecal dye study). It is valuable to understand the process and terminology regarding assessment of system integrity. CAP myelography is typically performed with fluoroscopy and requires aspiration from the CAP. If aspiration is not possible, myelography is not completed irrespective of imaging technique to prevent the risk of intrathecal overdose. Instead, complete imaging of the system is performed to ensure integrity. Recent work by Delhaas and Huygen suggests use of CAP-CT with myelography and 2D/3D reconstruction as a more accurate means of diagnosing intrathecal catheter dysfunction [3,4]. Other means of interrogating IDDS systems have been described including radionuclide scintigraphy. Choosing an interrogation process includes the consideration of cost, safety, availability, expertise, patient convenience and efficacy [5].

We reviewed charts of all 71 patients seen for intrathecal baclofen (ITB) pump management in a one-year period at a single facility. IRB exempt status was obtained from the institution for this chart review. Of the 71 patients reviewed, four were found to have experienced catheter-related dysfunction during the one-year period. Three of the 4 patients underwent routine pump exchange prior to catheter issues. Some had no known failures in therapy prior to surgery. All had catheters implanted prior to 2012. Given there is no known expiration or viability of previous catheter models, we provide suggestions for catheter and pump assessments to decrease the risk of, or to earlier detect, future catheter-related dysfunction.

2 Patient 1

An 83-year-old male with a 27-year history of ITB therapy for spastic quadriparesis underwent routine baclofen pump exchange. During surgery, it was noted the catheter had disconnected from the pump. It was unclear whether this occurred at the time of surgery or prior (long standing). The catheter was reconnected, and post-operatively, he did well. Three months later at routine pump refill, 22 cc more baclofen was retained in the pump than expected. Concerns for possible pump system failure and potential baclofen withdrawal prompted an urgent CAP myelography study. This could not be completed due to inability to aspirate through the catheter access port. A simple fluoroscopic survey was then performed and demonstrated a several centimeter breach in the catheter. It was the original catheter placed 27 years prior (catheter model 8703 W).

Prior abdominal KUBs from 7 to 4 years prior were reviewed. The images demonstrated that the tubing was intact 7 years prior but was fractured 4 years prior, indicating he had not received any ITB for at least 4 years. The chart and patient confirmed at no point had he experienced any sign of baclofen withdrawal.

His lower extremities remained flaccid without signs of spasticity. The subcutaneous baclofen dose was significantly reduced over 2 months.

3 Patient 2

A 39-year-old male with cerebral palsy, spastic quadriplegia and a 13-year history of ITB use presented for routine pump replacement. Four months prior to surgery he noticed increased spasticity and was receiving Botox injections. At surgery the catheter in the pocket was noted to be fractured (Fig. 1), and the spinal segment was found to be covered in thick granulation tissue which occluded the catheter lumen. It was the original catheter from 2009 (catheter model unknown, placed in 2009). After pump replacement and catheter repair, the ITB was reduced by 75 %. The subsequent days and weeks he reported improved spasticity and gait while eliminating his need for Botox injections.Fig. 1 Fluoroscopic image demonstrating distal spinal segment of the catheter disconnected from the pump at time of pump exchange.

Fig. 1

4 Patient 3

A 58-year-old female with thoracic myelopathy, spastic paraparesis and a 13-year history of ITB therapy (catheter model 8731) underwent a routine pump exchange for battery end-of-life, and reconnection of the catheter to the pump was properly performed and documented. She presented two weeks later after a fall with increased spasticity of the left lower extremity and pruritis suggesting withdrawal. At presentation, CAP myelography demonstrated appropriate continuity and was delivering medication to the intrathecal space. Due to frank baclofen withdrawal, she was taken back to the operating room to visually investigate the IDDS. During surgery, the catheter was properly connected to the pump, and CSF was aspirated from the catheter access port. However, administration of sterile saline into the access port revealed a dynamic catheter leakage (Fig. 2). Though no leak was noted at dye study, a leak was noted at the catheter connector during surgery depending on how the connector was rotated, indicating a presumed crack in the connector itself. The catheter and connector were replaced. Three days after catheter revision, she was back to baseline. We speculate the catheter-pump connection failure occurred as a result of the fall.Fig. 2 When sterile saline was injected into the access port, there was a stream of fluid coming from the connector with dynamic movement of the catheter.

Fig. 2

5 Patient 4

A 69-year-old female with primary lateral sclerosis, associated spasticity, and 12-year history of ITB use (catheter model 8590–9 InDura), presented with worsening spasticity. Thoracic and lumbar spine radiographs did not reveal obvious catheter fracture. CAP myelography was attempted but demonstrated inability to aspirate CSF. A complete fluoroscopic survey at that time revealed no catheter kink, fracture, obstruction or disconnect. A catheter revision was performed revealing a kinked and eroded catheter. The affected catheter was removed, and a spliced catheter reconnected.

6 Discussion

Ten of the 71 baclofen IDDS patients underwent surgical revision or routine pump exchange in a twelve-month period at our institution. Three of the cases represented above are of unrecognized or unidentified IDDS catheter dysfunction at the time of IDDS surgery. Catheter dysfunction was unrecognized at routine pump exchange in two of the cases. The other two were associated with a presumed, but unidentified, catheter dysfunction. Three of the four patients experienced symptomatic baclofen withdrawal requiring hospitalization for urgent workup and ultimately catheter revision. All of the cases involved older catheters made before 2012. Two had catheter breaks (fractures), one was dislodged, and one was kinked. Routine or better imaging before each of these surgeries could have expedited care and possibly reduced morbidity in this vulnerable population.

Irrespective of catheter model, intrathecal catheters remain a significant source of IDDS failure. The most recent Medtronic Implantable Systems Performance Registry (2016) followed 7266 intrathecal pumps and 6816 intrathecal catheters over a 10-year reporting period. They report 148 pump-related product performance events (2 %) vs 752 catheter-related product performance events (11 %). The most common reasons for pump-related performance events were motor stall or corrosion and/or gear wear (80 of 148 events)1. The most common catheter-related events were break, occlusion, dislodgement, and kink. While routine pump exchange is typically performed every 7 years due to end-of-life battery, there is no recommendation for routine catheter exchange or evaluation. Despite the newer catheters being marketed as having increased “strength and durability” compared to older catheters, the 2022 Medtronic Performance Report describes the average catheter survival drops to 69.9 %, for new catheters compared to 73.5 % for older catheters [2].

Delhaas and Huygen present an algorithm with novel imaging techniques for IDDS failure. They report by utilizing either low-dose single-energy CT (SECT) scan or catheter access port (CAP) CT myelography with 2D/3D reconstructions that IDDS product failures can be identified [3]. Utilizing these imaging techniques in a case series of 70 IDDS patients evaluated for delivery system failure, Delhaas demonstrated the CAP-CT myelography resulted in a sensitivity of 81 % and a specificity of 93 % in identifying catheter breaks, kinks, dislodgement and pump-catheter connection failure. The standard CAP myelography in identifying the same was a sensitivity 52 % and a specificity of 86 % [4].

In their case series of 70 patients, Delhaas et al. found that CAP myelography has a lower sensitivity for detecting IDDS failure than CAP-CT myelography (52 % vs 81 %), and the authors conclude that conducting CAP myelography under fluoroscopy alone is insufficient to diagnose IDDS failure [4]. Delhaas recommends using CAP-CT myelography and postprocessing 2D/3D processing when there is evidence of an IDDS issue, however we suggest that it could be a tool to detect IDDS issues before patients become symptomatic [3]. Three out of ten (30 %) of our patients who underwent surgery for routine pump exchange in a one-year period did not have symptoms of catheter dysfunction at the time of their pump exchange yet soon after were discovered to have catheter dysfunction. We speculate that in three of our patients, a more sensitive, proactive imaging technique may have identified the catheter dysfunction before surgery.

We are in the process of implementing CAP CT-myelography with postprocessing 2D/3D reconstruction in lieu of CAP myelography dye study not only for patients with presumed IDDS dysfunction, but also before end-of-life pump exchanges. These pumps have an average 7-year life expectancy which incidentally corresponds with a drop in the 7-year catheter life expectancy, particularly in the newer catheter models. Identification of early catheter dysfunction would.• assure continued spasticity therapy/management,

• avoid future episodes of withdrawal,

• avoid second surgery and associated complications,

• potentially reduce health care costs associated with a second surgery, and

• improve patient satisfaction.

We suggest obtaining CAP myelography dye studies, radiographs, or CAP-CT myelography with postprocessing 2D/3D reconstructions that fully visualize the catheter pump interface to the catheter tip when.• planning IDDS exchange or revision, including in asymptomatic patients with systems older than 7 years,

• baclofen needs increase and symptoms cannot be explained by disease progression,

• baclofen withdrawal symptoms are present, or

• pump refill anomalies occur such as more/less residual baclofen in reservoir than expected.

Again, myelography would only be indicated when able to aspirate from the CAP to prevent the risk of intrathecal overdose. Image scanning of the system or 2D/3D reconstruction could be performed irrespective of myelography.

7 Conclusions

We provide suggestions on when to further investigate the integrity of the catheters to decrease the risk of, or to earlier detect, future catheter-related dysfunction. By adopting our proposed process, we believe up to 80 % of the most common problems in the older and newer catheters—kink, dislodgement, occlusion and break—would be better identified. While we report on patients with baclofen IDDS, this proposed plan could benefit patients with IDDSs infusing any medication.

Funding statement

The authors did not receive any funding for this project.

Declaration of interests

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:Dr. Mauck serves on the editorial board for the Interventional Pain Medicine journal.
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