The Effect of Intrathecal Baclofen Therapy in Ambulatory MS Patients

Background: MS is a progressive disease that causes motor impairment including spasticity, and often affects ambulation. Intrathecal baclofen therapy (ITBT) has been shown to provide relief of spasticity in wheelchair-bound MS patients. ITBT is now being used to treat ambulatory MS patients, but the impact of this therapy on the patients’ ability to walk has not been well studied.

Objectives: To characterize the effects of ITBT on ambulation in MS patients with severe spasticity.

Methods: Data was extracted from the medical records of 49 ambulatory patients who received ITBT at our clinic and analyzed retrospectively. Primary outcomes were: ability to ambulate, Timed 25-Foot Walk (T25FW), and assistive device used. Statistical comparisons were made via two-tailed paired two-sample t-test or McNemar’s test.

Results: Our cohort consisted of 31 females and 17 males. Age at ITBT initiation was 48.6±8.4yrs. and duration of MS symptoms was 16.1±8.6yrs. Mean baseline time on the T25FW was 33.3±30.5s, with a mean change of -1.02s (p = 0.72) and 5.99s (p = 0.095) at 6 and 12 months, respectively. 6(20.7%) patients used no assistive device at baseline whereas 23(79.3%) used a unilateral or bilateral assistive device to complete the T25FW. This did not significantly differ at 6 months (no assistance - 3(10.3%); uni/bilateral assistance - 26(89.7%); p=0.18) but there was a significant increase in the proportion of patients using an assistive device at 12 months (no assistance – 2(6.9%); uni/bilateral assistance – 27(93.1%); p=0.045). Of the 49 patients, 36 and 33 remained ambulatory 6 and 12 months later, respectively. Those who remained ambulatory at one year walked faster on the T25FW at baseline than those who lost the ability to ambulate (22.07±18.19s vs. 61.99±38.53s; p=0.004).

Conclusions: Among patients who retained the ability to walk 1 year after initiation of ITBT there was no statistically significant change on the T25FW at 6 or 12 months, though use an assistive device increased significantly at 12 months. A subgroup of patients were unable to walk 25 feet at 6 (23%) and 12 (30%) months, but the potential contribution of ITBT to this functional decline, versus disease progression, remains to be determined.  Higher T25FW values (i.e. slower gait) at baseline were associated with a higher likelihood of becoming non-ambulatory 1 year after ITBT initiation. Further research is needed to better understand the effects of ITBT on ambulation in MS patients with severe spasticity.