Intrathecal Baclofen Therapy Underused

Intrathecal baclofen therapy (IBT; Lioresal) may be underused in stroke patients with spasticity, according to a new survey by the National Stroke Association. Of patients responding to the survey, 58% experienced spasticity. Of these, only half (51%) received any type of treatment for their condition. Although IBT has been shown to effectively reduce spasticity in patients with various types of brain injuries and diseases such as cerebral palsy and multiple sclerosis (MS), a mere 3% of patients surveyed were offered IBT. Commonly used rehabilitative treatments included motion exercises (58%); gentle stretching (51%); oral medications such as baclofen, tizanidine, and clonazepam (47%); and injectable medication (33%).

Baclofen is structurally similar to y-aminobutyric acid and binds to presynaptic y-aminobutyric acid-B receptors within the brain stem, dorsal horn of the spinal cord, and other sites in the CNS. Oral baclofen penetrates the blood-brain barrier poorly, so milligrams must be delivered daily. Intrathecal baclofen, however, is delivered directly to the subarachnoid space, so daily doses are in micrograms.¹

Besides being dose-sparing, IBT is better tolerated than oral baclofen. "It is much easier for a person to tolerate delivery of baclofen directly to the site where it's needed," remarked Mya Schiess, MD, associate professor of neurology at the University of Texas Medical School at Houston. "You bypass the system circulation, so you bypass the systemic side effects." Schiess currently treats more than 200 patients with IBT.

IBT generally has been reserved for use in nonambulatory stroke patients who experience severe spasticity, explained Schiess. One of the reasons for lack of broader use is the unfounded concern that the therapy would cause additional weakness and loss of function in healthy limbs. "The side effects of intrathecal baclofen therapy are fewer than some of the side effects of oral antispasmotic medications and can be more effective," she said. "I think neurologists also are hesitant to use intrathecal baclofen because they are not accustomed to advocating surgical interventions, yet the surgery itself is minimal."

"It's been heavily used in ambulatory and nonambulatory patients with traumatic brain injury, spinal cord injury, and multiple sclerosis," she added. "It is underutilized in the stroke population because there were some myths running around. Physicians fear that intrathecal baclofen can affect tone in limbs that had not been affected by a stroke in the hemiparetic stroke population. However, it is now well substantiated in the literature that this is untrue."

It is important to provide IBT for patients before they reach a nonambulatory state or before intractable spasticity develops, Schiess cautioned. "The therapy doesn't provide muscle strength; however, if abnormal tone will not allow a patient to use a muscle group or limb, that patient's muscles will eventually decondition and the patient will have increasing weakness. If you eliminate spastic tone, you allow a person to rehabilitate muscle strength in groups of muscle or limbs."

In their studies of the effects of intrathecal baclofen pumps in patients with stroke, Schiess and colleagues concluded that IBT is highly effective and well tolerated. In a study of 21 stroke patients aged 18 to 75 years who had spasticity for at least 6 months and in whom oral antispasmodic therapy had failed, muscle tone improved by an average 0.8 points per muscle group on the Modified Ashworth Scale following 12 months of IBT. Arm strength improved by an average 70% on the Manual Motor Test, and gait velocity increased by a mean of 60%.

DRAWBACKS TO THERAPY
Although Schiess has not observed many IBT-associated adverse events in the patients she treats, seizure and infection have been reported in other studies. A 2005 study by Stephan Schuele, MD, a resident, and colleagues in the Department of Neurology at the Cleveland Clinic, found a higher incidence of seizure in patients receiving IBT. The researchers followed 99 patients with MS and observed a higher incidence of epileptic seizures in patients treated with IBT (7%) than in patients given placebo (1%). However, the researchers concluded that additional triggering factors were associated with these seizures.²

A retrospective study by Linda Krach, MD, medical director of rehabilitation at Gillette Children's Specialty Healthcare, Department of Physical Medicine and Rehabilitation, University of Minnesota, St Paul, and colleagues examined the experience of 12 patients, aged 10 to 32 years, in whom Gram-negative infections developed after they received IBT.³ At the institution, a total of 571 baclofen pump surgeries had been performed from 1996 to 2003, and 45 resulted in infections. Of the 45 patients with infections, 12 had Gram-negative infections (2 of which resulted in meningitis); 10 of these infections occurred within 60 days of surgery. Pumps were explanted in 11 of the 12 affected patients. The Gram-negative infections were caused by Pseudomonas aeruginosa, Escherichia coli, Proteus, Enterobacter cloacae, Klebsiella, Enterobacter aerogenes, and Enterobacter vulnaris.

Children may be more likely than adults to have adverse reactions to IBT. John R. Vender, MD, associate professor in the Department of Neurosurgery, and colleagues at the Medical College of Georgia in Augusta conducted a retrospective review of complications encountered in a series of 314 pump- and catheter-related procedures in pediatric and adult patients. They looked at 314 procedures in 195 patients (226 pediatric, 88 adult) that had been performed by 2 surgeons during a 5-year period.⁴

Although no significant intraoperative complications were encountered, a higher percentage of procedures for complication management was seen in pediatric patients than in adult patients. New pump and catheter implants were required in 171 (116 pediatric, 55 adult) of the 314 procedures. Twenty-six (15 pediatric, 11 adult) elective pump replacements were made because the device's battery life had ended; 5 (3 pediatric, 2 adult) elective pump repositionings were made per physiatrist request; and 14 (10 pediatric, 4 adult) elective catheter repositionings and 2 pediatric catheter explorations with normal results were performed. Surgical procedures for complication management included 7 (5 pediatric, 2 adult) pump revisions, 48 (38 pediatric, 10 adult) catheter revisions, and 41 (37 pediatric, 4 adult) wound revisions. The majority of pumps implanted in adults were placed subdermally, whereas the majority of pumps implanted in pediatric patients were placed subfascially. IBT catheters were usually placed using fluoroscopic guidance. Catheter tips were placed at T1 to T2 for spastic quadriplegia, T6 to T10 for spastic diplegia, and midcervical for dystonia.

IMPROVING QUALITY OF LIFE
In general, Schiess believes that rehabilitation is not a significant focus for most physicians treating stroke patients. "The attitude is-if you're a survivor of stroke, good for you," Schiess said. "About 90% of the neurologist's effort is put into preventing future strokes. But now that it has come to everyone's attention that stroke is the leading cause of disability in the United States, we need to see what we can do to remedy that."

Study results have shown that treatment with IBT can significantly improve quality of life. A study by Collette Staal, RN, and colleagues at the Mary Free Bed Rehabilitation Hospital in Grand Rapids, Michigan, explored quality of life, complication rates, and length of IBT as reported by patients.

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Surveys from 49 (30 adult, 19 pediatric) patients were analyzed; 36 (73%) had undergone treatment with the pump for 1 year or more.

Of these patients, 43 (88%) said their quality of life had improved while they were receiving IBT. Positive effects included spasticity control without sedative effects, ease of care for caregivers, easier positioning, less pain/increased comfort, and improved patient transfers. Although there was a complication rate of 39%, 46 of the 49 patients (3 patients did not respond) surveyed said they would recommend the treatment to others.

Because of its positive impact on patient function, Schiess recommends that IBT be used earlier in stroke patients than has been previously reported in the literature. In 2005, a group of physicians including Schiess met to create guidelines for IBT use. "We feel it is certainly safe and appropriate to start using IBT when spasticity begins to impair function at 6 months and beyond," said Schiess. "People in the field had been saying this therapy should not be used until a patient has experienced spasticity for a year, but we feel it would be more beneficial earlier on. The thing is that there is no magic bullet. When abnormal tone presents, it does not go away-it does not have a period of remission. It can evolve over time to chronic spasticity."

REFERENCES1. Meythaler JM, Guin-Renfroe S, Brunner RC, Hadley MN. Intrathecal baclofen for spastic hypertonia from stroke. Stroke. 2001;32:2099-2109.
2. Schuele SU, Kellinghaus C, Shook SJ, et al. Incidence of seizures in patients with multiple sclerosis treated with intrathecal baclofen. Neurology. 2005; 64:1086-1087.
3. Wunderlich CA, Krach LE. Gram-negative meningitis and infections in individuals treated with intrathecal baclofen for spasticity: a retrospective study. Dev Med Child Neurol. 2006;48:450-455.
4. Vender JR, Hester S, Waller JL, et al. Identification and management of intrathecal baclofen pump complications: a comparison of pediatric and adult patients. J Neurosurg. 2006;104:9-15.
5. Staal C, Arends A, Ho S. A self-report of quality of life of patients receiving intrathecal baclofen therapy. Rehabil Nurs. 2003;28:159-163.