Intrathecal Baclofen In the Treatment of Adult Spasticity

Joseph C. Hsieh, M.D., M.B.A., M.P.H.; Richard D. Penn, M.D.

Disclosures

Neurosurg Focus. 2006;21(2) 

In This Article

Benefits

There is little doubt that ITB therapy fills a critical role in the treatment of spasticity. The primary benefit of ITB is the relief of severe spasms and spasticity. Overall, pa-tients report increased independence, mobility, and ability to perform self-care. Some patients report that they have a more consistent sleep pattern at night; others report re newed ability to have sexual intercourse. Urinary function improves in some as detrusor hyperreflexia and bladder contractions are curtailed. Muscle pain and fatigue accompanying spasm is minimized with ITB, partly because of the reduction in spasms, and possibly also because ba clofen acts as an antagonist to substance P in suppressing central pain.[14] Ultimately, the dose level of ITB is set in a fashion to relieve spasticity while preserving voluntary movement and limiting side effects. Oral baclofen may be weaned over several weeks to prevent withdrawal symptoms of delirium, hallucinations, or seizures.

Reflexes have been found to be particularly improved. Latash, et al.,[18] observed mono- and polysynaptic reflexes and voluntary movements in the lower extremities in patients with chronic refractory spasticity treated with a single bolus of ITB. Responses on EMG studies to joint movements, H-reflexes, ankle clonus, and defensive reactions in the lower extremities were significantly reduced within 30 to 45 minutes and almost completely suppressed by 2 hours. There was also improvement in selective voluntary activation of leg muscles in those with residual mo tor control. Because ITB exerts an almost purely spinal effect with little or no supraspinal effect due to its concentration gradient, this evidence suggests that supra spin al central motor commands may be somewhat intact des pite long-term spasticity in some patients.

Intrathecal baclofen reduces nocturnal disturbance caused by spasticity. Little, et al.,[19] reported diurnal variation in different types of spasticity, with flexor spasms occurring most frequently at night in 50% of patients. Indeed, spasticity interfered with sleep in 82% of patients with incomplete lesions and in 50% of patients with complete lesions. Baclofen infusion improves sleep by reducing these spasms. The activity per hour of the tibialis anterior muscles was reduced during sleep, according to re sults of EMG studies performed after baclofen infusion, and this lower activity led to reduced sleep disturbance.[16]

Baclofen appears to work in patients suffering from spas ticity of either spinal or cerebral origin. For instance, Ordia, et al.,[29] studied 59 patients suffering from severe spasticity of spinal cord origin that was refractory to oral baclofen (for example, spinal cord injury, multiple sclerosis, familial spastic paraparesis, spinal cord tumor, cervical spondylotic myelopathy, transverse myelitis, and amyo trophic lateral sclerosis). In this series, the mean Ash wor th rigidity score significantly decreased, from 4.3 to 1.4 (p < 0.0005), and the spasm frequency score decreased from 3.6 to 0.5 (p < 0.0005).

Baclofen also appears to work in patients suffering from cerebral spasticity. Meythaler, et al.,[22] studied 17 patients with stroke who had chronic spasticity lasting longer than 6 months, in whom the Ashworth lower-ex tre mity scores were reduced an average of 2 points during screening. In this series, the mean Ashworth score in the lower extremities after pump implantation had declined at 1 year from 3.7 to 1.8 (p < 0.0001), the spasm score from 1.2 to 0.6 (p = 0.43), and the reflex score from 2.4 to 1 (p < 0.0001). The mean Ashworth score in the upper extremity declined from 3.2 to 1.8 (p < 0.0001), the spasm score from 0.7 to 0.3 (p = 0.87), and the reflex score from 2.4 to 1.5 (p = 0.33).

In another study, Meythaler, et al.,[23] evaluated 13 pa tients with CP who had intractable spastic hypertonia and quadriparesis refractory to oral medications who dropped an average of 2 points on their Ashworth lower-extremity scores during screening. In this series, the mean Ashworth score in lower extremities after pump implantation had declined at 1 year from 3.4 to 1.5 (p < 0.0001), the spasm score from 1.4 to 0.6 (p = 0.1024), and the reflex score from 2.5 to 0.7 (p < 0.0001). The mean upper-extremity Ash worth score decreased from 3 to 1.7 (p < 0.0001), the spasm score from 1.2 to 0.2 (p = 0.0135), and the reflex score from 2.3 to 0.5 (p < 0.0001).

Intrathecal baclofen appears to be cost-effective at an institutional level. Ordia, et al.,[29] found a reduction in the length of hospital stays but no change in overall use of outpatient resources during the 1st year after pump im plan tation. Patients reduced their mean hospital stays of 7.9 days/year preimplantation to 5.7 days/year in the 1st year postimplantation, with a cost savings of $6750 per pa tient (excluding the cost of pump implantation). As suming that reduction in hospital days continues beyond the 1st year, the cost of implanting the system is paid back in less than 2.5 years on average.

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