P021: INTRATHECAL PUMP VERSUS SPINAL CORD STIMULATOR: A POTENTIALLY LIFE ALTERING AND DISASTROUS THERAPY IN EPENDYMOMA TREATMENT
David McEnerney, DO; Dan Yarnovsky; Seung Lee, MD; University of Maryland Medical Center
Introduction: Intrathecal pump (ITP) and Spinal cord stimulation (SCS) are both implantable devices that help manage chronic pain. ITP can deliver morphine, bupivacaine, ziconotide, and clonidine to the subarachnoid space leading to decreased pain scores and fewer systemic side effects. SCS, however, does not involve medication and instead utilizes Gate Theory, a mechanism by which electrical stimulation of the spinal cord dorsal columns replaces noxious stimuli with a vibratory sensation. In the following patient case, we will see both the benefits and potential disadvantages of ITP over SCS as a treatment for neuropathic pain.
Case Description: The patient is a 53 year old female with a 24 year history of chronic pain due to a recurrent ependymoma of the lumbar spine. She underwent chemotherapy, multiple laminectomies of the lumbar spine, and tumor resections before remission. During her treatment course she developed severe bilateral lower extremity neuropathic pain that was resistant to medical management. At the time, a discussion was had whether to place a SCS or ITP. An ITP with morphine and bupivacaine was chosen due to her history of cancer with the possibility of recurrence. The patient received excellent analgesia from the ITP and was able to wean off of oral narcotics and neuropathic pain medications.
Four years later on surveillance MRI an ependymoma was found that caused a spinal cord injury leading to paraplegia. At this point, the patient began developing severe spasticity of her lower extremities. Through a weaning process her morphine and bupivacaine was changed to baclofen, which helped reduce the frequency of severe spasms for the next six years.
Following the switch to baclofen, she was admitted for purulent discharge from the pump site. After a failed course or oral antibiotics and irrigation and debridement the decision was made to remove the pump. The patient was placed on high dose oral baclofen after removal, but went into baclofen withdrawal and was admitted to the intensive care unit (ICU). She had a lengthy stay in the ICU, but eventually was discharged to a rehab center.
Discussion: For this patient, an ITP was chosen to treat her neuropathic pain, as well as in anticipation of possible cancer pain, the need for future MRIs, and more flexibility for converting to different therapies. While a SCS could provide similar neuropathic pain relief, it would be limited to the spinal cord level it was placed at, making it ineffective at treating any cephalic disease progression. Unfortunately, the risk of bleeding, infection, and damage to surrounding structures is present with any implantable therapy, and should be considered prior to proceeding. An infection that led to ITP therapy failure for this patient resulted in acute baclofen withdrawal, which can be life-threatening. The decision to place an advanced pain therapy involves careful consideration of the advantages and disadvantages of each therapy, which is highlighted in the case presentation.