Cerebrospinal fluid baclofen concentrations in patients undergoing continuous intrathecal baclofen therapy

The aim of this study was to report concentrations of cerebrospinal fluid (CSF) baclofen in children undergoing chronic intrathecal baclofen (ITB) infusions. CSF baclofen concentrations were analyzed in 53 specimens obtained by intrathecal catheter aspiration from 43 participants (28 males, 15 females; range 3-44y, mean 16y [SD 8y 11mo]), with functioning baclofen pumps and catheters. Daily ITB doses ranged from 70 to 1395 mu g per day (mean 607 mu g per day [SD 363], median 575). Baclofen concentration was quantified by high-pressure liquid chromatography and confirmed by injection onto a gas chromatograph. CSF baclofen concentrations from children receiving either simple continuous or complex infusions ranged from 0.2 to 20.0 mu g/ml (mean 4.64 mu g/ml, median 3.3 mu g/ml). CSF baclofen concentrations from children receiving simple continuous infusions ranged from 0.5 to 12.9 (mean 4.7 mu g/ml, median 3.55 mu g/ml). There was no correlation between ITB dosage and CSF baclofen concentration. We conclude that baclofen concentration can be measured to determine if baclofen is present in CSF. However, there appears to be no correlation between the ITB dose infused and the corresponding CSF baclofen level.