Neurologic safety of baclofen use after a spinal cord injury

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Lay Summary by Lauren Eggenberger

Edited by Rona Herzog

This is a summary of a research study conducted with ICORD researchers Dr. Jacquelyn Cragg, Bobo Tong, Catherine R. Jutzeler, Freda M. Warner, Dr. John Kramer, and their colleagues. Click here to access the original paper.


What is baclofen and why is it important to study? 

In addition to reduced sensation and paralysis, another complication of spinal cord injury (SCI) is muscle spasms. Muscle spasms are often treated with the addition of the drug, baclofen, which is a central nervous system (CNS) antagonist. This means the drug acts by binding to specific receptors in the CNS, decreasing their activity, which leads to a reduction in random muscle contractions.

Despite baclofen being used as a drug used to treat some of the secondary complications of SCI, it has not been previously studied during the acute phases of injury. The acute phases of injury, also known as the recovery phase, starts from the instant the injury occurs and can last for weeks or months. Due to safety concerns surrounding baclofen, it is not used during the “recovery phase” in other conditions such as stroke and multiple sclerosis; however this is not based on scientific evidence. The main goal of this paper was to determine the safety of baclofen usage during the acute (recovery) phase of SCI. 

How was this study conducted?

This study re-examined the 1992-1998 United States Food and Drug Administration Sygen spinal cord and injury clinical trial data, (more information on this study can be found here). This trial was originally conducted to test the efficacy of another drug, GM1 ganglioside, administered during SCI recovery.  In order to be included in the trial, participants needed to have complete sensory and motor scores taken within 72 hours post injury. The study monitored patients for one year post SCI. This included tracking all medications being taken, as well as the marked recovery* of individuals as indicated by an increase in their sensory and/or motor ability scores. In total, 651 of the original patients were included in this re-examination analysis. 

Is baclofen use safe during the acute phase of SCI recovery?

The results of this study showed that the addition of baclofen within the four-week period post injury showed no damaging effects to marked recovery and in fact, higher doses of Baclofen were related to increases in marked recovery for individuals with AIS A and C/D grades. 

What do these findings mean for people with SCI?

These findings provide support for the use of baclofen during recovery of SCI and disprove the notion that baclofen is unsafe to use during this period. This analysis provides more information about a safe medication option to manage muscle spasticity and involuntary muscle spasms during the first month of SCI recovery.  

What are the limitations of this study?

The exact mechanism by which baclofen use increases marked neurological recovery is not known, but many researchers believe that it could function by reducing muscle spasms which could allow muscles to regain strength. However, it is important to note that other antispasmodic medications did not provide this same benefit; this supports the idea that it is the use of baclofen, specifically, that causes an increase in marked recovery, as opposed to the effect of reducing muscle spasms causing an increase in marked recovery. Researchers suggest that future studies should look at the causality between central nervous system activity, baclofen use and neurological recovery.  

Note:

*“Marked Recovery”, which is defined as a transition to a higher sensory and motor function, was a primary outcome of the secondary analysis. This outcome was based on Benzel grades and the American Spinal Association Impairment Scale (AIS) grades.

Note:

*“Marked Recovery”, which is defined as a transition to a higher sensory and motor function, was a primary outcome of the secondary analysis. This outcome was based on Benzel grades and the American Spinal Association Impairment Scale (AIS) grades.

Type of Grading Benzel Grades  AIS Grades
Grading Reference Indicates ability to walk with/without assistance using a scale of 1 to 7

Examines walking in terms of limited or unlimited function

Takes into account secondary factors that can limit an individual’s walking mobility, including lack of endurance or fear of falling 

Indicates level of injury completeness 

AIS A/B are motor complete

AIS C/D are motor incomplete 

 

For this Study ‘Marked Recovery’ was determined by: 

Grade prior to Baclofen use:  AIS-A and AIS-B injuries  AIS-C and AIS-D
What is the marked recovery after Baclofen use: A change in AIS grade to AIS-C and AIS-D (respectively) Recovering of limited or unlimited walking function (respectively) determined by a change in Benzel grades 
What does this mean? Entails a regaining of sensory and motor function below the level of injury Entails a change in the individual’s ability to walk with/without assistance 

 

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