Hello everyone. Thank you for taking the time to stop by and look at my poster. My name is Nathan Truax, and I am a PGY3 at the University of Utah. Today, I would like to present to you a case series involving two cases seen in our outpatient clinics involving refills of intrathecal backlift and pump reservoirs that led to overdose symptoms requiring hospitalization. These cases are novel in that withdrawal symptoms are typically seen with pocket fills. However, in these two cases, overdose symptoms are seen. Spasticity is defined as a velocity-dependent increase in muscle tone. Many treatment options exist, but we will be focusing on intrathecal baclofen today. As many of you likely know, baclofen is probably the most common drug used intrathecally for the management of severe spasticity. It is a GABA agonist at neurons in the spinal cord and brain. It is delivered intrathecally by a pump attached to a catheter. As you can see in Figures 1 and 3, the pump is surgically implanted in the subcutaneous tissues, usually in the abdomen. The pump is then connected to a catheter that runs into the intrathecal space, and the pump is programmed to deliver a set amount of medication over time. The pump has a reservoir that is refilled at set intervals based on the patient's needs. Figure 2 illustrates how the pump is accessed. Typically, a guide is placed over the pump, and a needle is inserted into the reservoir. Any excess baclofen is aspirated, and the reservoir is refilled with baclofen. Occasionally, the baclofen is injected around the pump and into the pocket, also known as a pocket fill. Typically, when this happens, the drug is not delivered via the pump into the intrathecal space, and the patient begins to experience withdrawal symptoms. However, we recently had two cases that experienced pocket fills that led to overdose-type symptoms. The first case involves a 44-year-old female who presented for routine refill in clinic. Her pump was refilled, and while she was still in clinic, began to start experiencing progressive numbness and weakness. She was brought over to the ED and was eventually intubated and admitted to the ICU. A serum baclofen level was drawn and resulted at 1 microgram per milliliter, over double the upper limit of therapeutic range. She began to experience seizures in hospital day one, which were responsive to Keppra. She was then taken to IR, interventional radiology, where very little fluid was aspirated from her pump, only half a milliliter. 23 milliliters of fluid was removed from the peripump area. Eventually, she was dialyzed with steady improvement, and a two-month follow-up had returned to her previous baseline level of activity. The second case involved a 59-year-old male presented for pump refill to interventional radiology. He had been undergoing pump refill under fluoroscopic guidance due to difficulty accessing his pump because of abdominal obesity. He tolerated the procedure well and returned to his care facility, where he was found unresponsive four hours later. He also had a witness to seizure en route with EMS and presented to the ED in status epilepticus. He was also a reflexive with hypotension, requiring pressors. He was taken to IR for pump access as well, where 18 milliliters of fluid was aspirated from the space anterior to his pump. This was sent to the lab and was found to be baclofen. He, too, underwent dialysis with improvement and eventually returned to his previous baseline. Pocket fills are overall a relatively uncommon occurrence, with studies estimating incidence at 0.03% of fills. Most instances of pocket fills result in withdrawal. However, interestingly, these two cases presented with overdose. In order for this to happen, baclofen likely would have needed to cross the blood-brain barrier. If it had entered systemic circulation, the doses of 80 milligrams and 40 milligrams would be highly unlikely to cause such profound overdose symptoms. We have hypothesized that baclofen injected into the pocket, tracked along the outside of the catheter and into the intrathecal space, causing the signs and symptoms seen. In conclusion, pocket fills are a rare but serious complication of baclofen pumps. Typically, these fills result in withdrawal, but we present here two cases of an overdose caused by pocket fills. Treatment of baclofen overdose is largely supportive, with hemodialysis being able to remove 80% of baclofen with a single session. Further research is still needed to assess safety outcomes with pump refills. I would like to thank my mentors and co-authors on the project, Drs. Stephen Edgeley and Michael Green, as well as Dr. Robert Shingleton, for providing their expertise, advice, and recommendations throughout this project. I would also like to thank all of those who have worked at the Craig Agneson Rehab Hospital at the University of Utah. We are truly fortunate to have a state-of-the-art facility to provide excellent care for our patients. Thank you again to all those of you who posted your questions.

case series

intrathecal baclofen pumps

overdose symptoms

pocket fills

blood-brain barrier