Tolerance to Intrathecal Baclofen For Amyotrophic Lateral Sclerosis-Associated Spasticity: Analysis of Outcomes and Predictors of Onset

Shearwood McClelland III M.D.¹, Francois A. Bethoux M.D.², Matthew H. Sutliff P.T.², Darlene K. Stough R.N.², Kathleen M. Schwetz R.N.², Danuta M. Gogol R.N.², Michelle Harrison P.T.², Erik P. Pioro M.D., Ph.D.², Nicholas M. Boulis M.D.³

¹Department of Neurosurgery, University of Minnesota Medical School, Minneapolis, MN; ²Department of Neurology, The Cleveland Clinic Foundation, Cleveland, OH; ³Department of Neurosurgery, The Cleveland Clinic Foundation, Cleveland, OH.

Introduction:

Intrathecal baclofen (ITB) pump placement is commonly reserved for the treatment of medically refractory spasticity. The potential issue of tolerance to ITB has not been rigorously examined previously. We reviewed a cohort of amyotrophic lateral sclerosis (ALS) patients with intractable spasticity requiring ITB to further define the impact of tolerance (defined as greater than double the initial dosage at/within one year of surgery) on this patient population.

Methods:

From 2003-2005, ten patients (6M, 4F) with intractable ALS-associated spasticity underwent ITB placement at our institution. Mean age at surgery was 46.6 years (range: 33-77), and average ALS duration was 51 months (range: 13-120). All patients had a positive response to preoperative ITB test injection (25-50 mcg), and were subsequently implanted with a programmable intrathecal infusion system. Dosages of baclofen at surgery and at/within one year postoperatively were examined to investigate the development of tolerance. Mean follow-up was 8.1 months (range: 3-12).

Results:

Following ITB placement, 4 patients developed tolerance, three of which did within 3 months of implantation. Neither age under 45 (p=0.09) nor duration of ALS longer than 3 years (p=0.74) were predictive of subsequent tolerance development.

Conclusion:

In the first report examining tolerance to ITB placement in ALS-associated spasticity patients, 40% of patients developed tolerance, of which 75% did so within the first three months following surgery. Neither age at surgery nor duration of ALS was independently predictive of subsequent tolerance development. This report underscores the importance of early postoperative ITB evaluation in the management of potential tolerance.

Keywords:

Spasticity, Intrathecal Baclofen, Tolerance, Amyotrophic Lateral Sclerosis