Managing Complications of Intrathecal Baclofen Therapy

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Facilities with strict protocols to prevent problems have been able to report significantly lower complication rates. <i>Credit:Dr P. Marazzi/Science Source</i>
Facilities with strict protocols to prevent problems have been able to report significantly lower complication rates. Credit:Dr P. Marazzi/Science Source

Intrathecal baclofen (ITB), delivered via an implanted pump, carries primary indications for the reduction of spasticity in children resulting from spinal cord injury, or associated with cerebral palsy or multiple sclerosis.1,2 According to a recent review by Winter et al,1 the use of ITB is expanding in the pediatric population to include a number of metabolic or neurodegenerative conditions. It is most commonly used to treat both spasticity and secondary dystonia in cerebral palsy, as primary dystonia does not respond to baclofen therapy.1

Intrathecal baclofen has been shown to significantly improve functional outcomes in gait, sitting, and crawling, as well as upper extremities, which improves activities of daily living and quality of life among young children. However, these benefits must be weighed against the risk for complications associated with ITB therapy, estimated to be as high as 25% to 30%.1-3

Complication Rates

A 2014 study by Motta and Antonello found that 25% of pediatric patients experienced at least 1 complication over the course 14 years.4 Complications of ITB are usually directly related to 1 or more issues involving the surgical implantation procedure, mechanical failure of catheter/pump devices, and issues with the baclofen drug therapy, including withdrawal and overdose.

Facilities with strict protocols to prevent problems have been able to report significantly lower complication rates. Mary-Lynn Chu, MD, pediatric neurologist at Hassenfeld Children's Hospital and director of pediatric services at the Orthopedic Hospital at NYU Langone in New York City, estimates that issues with ITB therapy are less than 10% at their facility. "We have an excellent system to ensure patients do not miss their refill dates, and this would be [the] number 1 reason for withdrawal," she told Neurology Advisor. The Department of Rehabilitation at Children's Hospital of Colorado also reports a complication rate of about 10%, according to Kim Sawyer, CPNP, who works directly with pediatric patients who have a baclofen pump. "Our most common complication is catheter obstruction. We also see infection after placement, replacement, or new placement of spinal hardware," she said.

Surgical Complications

The first stage of ITB therapy involves neurosurgical introduction of a catheter under the skin into the intrathecal space (usually between the T8 and T10 vertebrae), which is then connected to a baclofen pump implanted under the skin to 1 side of the abdomen. Implantation complications resulting from the surgery or failure of the device usually arise within 6 months of the procedure.

Device-Related Complications

The most common types of complications seen with ITB are catheter-related, involving infections (usually Staphylococcus aureus) at a rate of 1% to 5% within the first 6 weeks; a 5% to 15% rate of catheter migration;and an incidence of cerebrospinal fluid leaks of about 1% per month.4

This is often a result of older catheters in patients, Dr Chu reported, which sometimes have microtears or may disconnect or move out of the space. "The newer catheter, which has been around for more than 6 years and which most of the patients have, appears to be more reliable since we have not heard of issues with microtears," she said, noting that at Hassenfeld, they do not preventively change the previous catheter in patients who have reported no issues.

For complications involving failure of the pump device itself, clinicians will manage symptoms and refer the patient back to neurosurgery for replacement of the pump. "If a patient has an active infection and the device needs to be removed, the patient is usually titrated down and managed with [intravenous] benzodiazepines and other drugs," Dr Chu explained.

Often, complications will develop with no apparent cause, necessitating clinical evaluation of the entire treatment protocol. Dr Chu elaborated on several approaches to evaluating the integrity of the baclofen pump system, including the catheter. "If slowly increasing baclofen-resistant spasticity develops in spite of dose increases, it suggests a need to interrogate the pump to determine the amount of ITB in the pump reservoir," she said. When the reservoir is not low, then catheter continuity would be investigated next. An X-ray of the abdomen can help determine catheter position ir reveal a disconnection of the catheter from the pump, kinking of the catheter, or malrotation of the pump. Another method is to check for access to the side port on the pump. "If we can withdraw the drug, for the most part we know the catheter is intact. If the catheter is not intact, then we refer to neurosurgery," she said, noting that a catheterogram can also be done to check continuity.

Baclofen Withdrawal

Sudden interruption of baclofen therapy can result in baclofen withdrawal, which is recognized as a serious medical emergency. Dr Chu noted that symptoms of withdrawal "usually present close to their scheduled refill dates, and 40% are due to catheter-related problems. Other causes include infected pump removal, empty reservoir volume, end of battery life, and iatrogenic programming error." 

Rebound spasticity is the earliest symptom, and can be associated with tachycardia, fever leading to hyperthermia, itching, paresthesias, or seizures. In addition, patients can have neuropsychiatric symptoms such as hallucinations, delirium, delusions, and paranoia, she said, whereas severe symptoms might include malignant hyperthermia, autonomic instability, rhabdomyolysis, diffuse intravascular coagulopathy, and multiorgan system failure.

"The main symptoms of baclofen withdrawal include increased tone, agitation, fever, and pruritus," Ms Sawyer explained. "We try to rule out other causes of agitation/tone such as pain stimulus (fracture, wounds, intestinal pain including kidney stones, gall stones, or appendicitis), constipation, anxiety, or infection. If no other etiology is found, we look at ITB programming and ensure that they have the correct medication concentration, dosing, and available drug. If the patient has missed an ITB refill, will refill the ITB pump. We typically access the side port and withdraw 3 mL of fluid; if we are unable to withdraw fluid, they have a presumed catheter obstruction or disconnect and will be scheduled for surgical catheter revision. If fluid is withdrawn without problem and programming is within normal limits, we will administer a single bolus via ITB pump (usually 50 μg) and monitor for response 4 hours later."

Baclofen Overdose

A similarly serious complication is baclofen overdose, which Dr Chu stated presents with signs of hypotension, bradycardia/tachycardia, hypotonia, flaccid paralysis, somnolence, delirium, respiratory depression, seizures, or cardiac abnormalities, and is characterized by rapid deterioration with profound respiratory depression/coma. "There is no specific antidote for reversing overdose symptoms," she said, emphasizing the need for supportive intensive care unit care, along with careful monitoring for signs of withdrawal. "In acute ITB overdose, the delivery of baclofen via the pump should be stopped for a maximum of 48 hours. Then, either replace reservoir with saline or restart at a minimum rate (nontherapeutic dose) to prevent damage to [the] pump. In severe cases, we can decrease the baclofen load by withdrawal of 30 cc to 40 cc of cerebrospinal fluid via lumbar puncture. Before restarting the pump, concentration of the drug in the tubing and catheter needs to be taken to account to avoid complications of further overdose," Dr Chu said.

The procedure is similar at Children's Hospital of Colorado. "If a patient presents with signs/symptoms of baclofen overdose, we monitor respiratory status and offer respiratory support as needed, start clean intermittent cathing if needed, and decrease ITB pump dose by 25% to 40%," Ms Sawyer reported. "It typically takes a while for a patient's symptoms to resolve from overdose, so watch for change over the next 12 hours and continue to decrease ITB dose if there is no improvement (or not enough improvement)," she said.

References

  1. Winter G, Beni-Adani L, Ben-Pazi H. Inthrathecal baclofen therapy—practical approach: clinical benefits and complication management. J Child Neurol. 2018;1-8.
  2. Borrini L, Bensmail D, Thiebaut JB, et al. Occurrence of adverse events in long-term intrathecal baclofen infusion: a 1-year follow-up study of 158 adults. Arch Phys Med Rehabil. 2014;95:1032-1038.
  3. Stetkarova I, Brabec K, Vasko P, Mencl L. Intrathecal baclofen in spinal spasticity: frequency and severity of withdrawal syndrome. Pain Physician. 2015;18:E633-641.
  4. Motta F, Antonello CE. Analysis of complications in 430 consecutive pediatric patients treated with intrathecal baclofen therapy: 14-year experience. J Neurosurg Pediatr. 2014;13:301-306.
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