Baclofen
Baclofen is a gamma-aminobutyric acid B agonist that is commonly used for the management of spasticity from central nervous system lesions or dysfunction and it is extensively used for SCI, stroke, cerebral palsy and multiple sclerosis (McCormick et al. 2016; Dietz et al. 2023). Baclofen for SCI can be administered orally or intrathecally with implantation of a metered pump (Dietz et al. 2023). Through the oral delivery of baclofen, greater doses than intrathecal delivery may be required for optimal effects, as only a fraction of the medication may pass through the blood-brain barrier (McCormick et al. 2016). However, while the intrathecal delivery of baclofen uses lower doses in comparison, it requires a more invasive approach and commitment to regular maintenance for the surgical placement of an internal pump and a catheter system (McCormick et al. 2016). McCormick et al. (2016) compared these two delivery methods of baclofen treatment and their effects on clinical outcomes such as fatigue.
Discussion
McCormick et al. (2016) compared the two methods of baclofen delivery and how clinical measures of fatigue, spasticity control, pain, sleepiness, and quality of life may be affected by each in participants who have been receiving baclofen for the treatment of spasticity. While the results showed improvements in spasm frequency and severity with intrathecal delivery in comparison to oral delivery, there were no significant differences in fatigue between groups (neither in the whole sample nor in the SCI sample; p=0.68-0.80). In a cross-sectional survey of 24 individuals (nine with SCI) who have been using intrathecal baclofen for more than 10 years, Mathur et al. (2014) reported low levels of pain, moderate levels of life satisfaction, normal levels of sleepiness, low-to-moderate levels of fatigue, infrequent spasms at mild-to-moderate severity, and high levels of satisfaction; however, no pre-post comparison was made (Mathur et al. 2014).
These positive results in spasticity outcomes, favoring intrathecal delivery, were consistent with results obtained in a recent systematic review of 98 studies that assessed the efficacy, dosing, and safety profiles of intrathecal and oral baclofen in treating spasticity after SCI (Dietz et al. 2023). However, this systematic review also found that 43 studies addressed adverse events and reported that muscle weakness and fatigue were the most frequent ones (Dietz et al. 2023). There are no further studies with a specific clinical population assessing the effects of baclofen regarding fatigue as an outcome.
Conclusions
There is level 2 evidence (from one cohort study: McCormick et al. 2016) that intrathecal baclofen resulted in fewer and less severe spasms in people with SCI compared to oral baclofen as measured by the Penn Spasm Frequency Scale. However, there were no significant differences in pain, sleep, fatigue, and quality of life between groups.
