Effects of Serotonergic Medications on Locomotor Performance in Humans with Incomplete Spinal Cord Injury

JOURNAL OF NEUROTRAUMA, 2014 · DOI: 10.1089/neu.2013.3206 · Published: August 1, 2014

Spinal Cord Injury Pharmacology Rehabilitation

Simple Explanation

Incomplete spinal cord injury (iSCI) often leads to motor impairments, reducing functional mobility. This may be due to a loss of serotonin input to spinal circuits. Spastic motor behaviors in SCI are sometimes attributed to changes in spinal serotonin receptors, augmenting their activity, which can be contradictory to other findings about motor effects. This study investigates the effects of medications affecting serotonin on locomotion in chronic iSCI patients, examining gait kinematics, muscle activity, and oxygen consumption.

Study Duration

Not specified

Participants

10 male subjects with chronic motor iSCI

Evidence Level

Not specified

Key Findings

1
Neither SSRIs nor 5HT antagonists improved locomotion in iSCI subjects.
2
5HT antagonists significantly decreased peak overground gait speed.
3
5HT medications had differential effects on EMG activity, with 5HT antagonists decreasing extensor activity and SSRIs increasing flexor activity.

Research Summary

This study evaluated the acute effects of serotonergic medications on locomotor performance in individuals with incomplete spinal cord injury (iSCI). The study found that administration of a 5HT antagonist resulted in significantly decreased peak overground speed, while SSRI administration resulted in no significant changes. Detailed evaluation of muscle activity and gait kinematics demonstrated few differences at fastest treadmill speeds. However, comparisons at fastest matched speeds revealed increased flexor muscle activity after SSRI and decreased extensor activity with 5HT antagonists.

Practical Implications

Clinical Practice

Single-dose administration of neither 5HT medication led to improvement in locomotor function.

Further Research

Additional research is needed to determine the effect of pairing pharmacological agents with specific interventions in humans with iSCI.

Understanding Mechanisms

Further investigation is required to determine the relationship between locomotor function and lower-extremity strength and muscle activity.

Study Limitations

1
The study only assessed acute effects of single-dose administration, which may not reflect the effects of chronic medication use.
2
The sample size was relatively small (n=10), which may limit the generalizability of the findings.
3
The study population consisted of individuals with AIS D iSCI, which may not be representative of all individuals with iSCI.

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