From the Guidelines
The primary mechanism of action for treating muscle spasms in patients with Spinal Cord Injuries (SCI) involves the use of agents that act as GABAB agonists, such as baclofen, which reduces muscle tone by inhibiting the release of excitatory neurotransmitters in the spinal cord. The treatment of muscle spasms in patients with SCI is crucial for improving their quality of life and reducing morbidity. When considering the management of patients with spinal cord injury, the focus is on multimodal analgesia strategies that can include non-opioid analgesics, antihyperalgesic drugs, and opioids, as recommended in the French guidelines for the management of patients with spinal cord injury or at risk of spinal cord injury 1. However, for muscle spasms specifically, the agent used, such as baclofen, works by binding to GABAB receptors in the spinal cord. This binding inhibits the release of excitatory neurotransmitters and reduces the hyperexcitability of motor neurons, thereby decreasing the frequency and intensity of muscle spasms. Key points about the mechanism of action include:
- Binding to GABAB receptors
- Inhibition of excitatory neurotransmitter release
- Reduction of motor neuron hyperexcitability
- Decrease in muscle spasm frequency and intensity Given the importance of managing muscle spasms effectively in patients with SCI to prevent complications and improve quality of life, the use of a GABAB agonist like baclofen is a critical component of their care, with the potential for intrathecal delivery for those with severe spasticity not adequately controlled by oral medication.
From the FDA Drug Label
The precise mechanism of action of baclofen is not fully known. Baclofen is capable of inhibiting both monosynaptic and polysynaptic reflexes at the spinal level, possibly by hyperpolarization of afferent terminals, although actions at supraspinal sites may also occur and contribute to its clinical effect The mechanism of action of baclofen in treating muscle spasms in patients with Spinal Cord Injuries (SCI) is not fully known. However, it is believed to involve the inhibition of monosynaptic and polysynaptic reflexes at the spinal level by possible hyperpolarization of afferent terminals 2.
From the Research
Mechanism of Action of Agents Used to Treat Muscle Spasms in Patients with Spinal Cord Injuries (SCI)
The primary agents used to treat muscle spasms in patients with SCI include baclofen, botulinum toxin type A, and other medications such as benzodiazepines and dantrolene sodium.
- Baclofen is a GABA receptor agonist that acts on the central nervous system to reduce spasticity by inhibiting the transmission of nerve signals that cause muscle spasms 3, 4, 5, 6.
- Botulinum toxin type A works by blocking the release of acetylcholine, a neurotransmitter that stimulates muscle contractions, thereby reducing muscle spasms 4, 7.
- Benzodiazepines and dantrolene sodium also have a role in reducing spasticity, although their mechanisms of action are different from those of baclofen and botulinum toxin type A 3, 5.
Administration Routes and Treatment Approaches
The administration routes and treatment approaches for these agents vary:
- Baclofen can be administered orally or intrathecally, with intrathecal administration often used for severe cases of spasticity 3, 4, 6.
- Botulinum toxin type A is typically administered via injections into the affected muscles 4, 7.
- A combination of these treatments, along with rehabilitation programs, may be used to manage spasticity in patients with SCI 4, 7, 6.
Efficacy and Safety of Treatments
The efficacy and safety of these treatments have been studied in various clinical trials and case reports:
- Intrathecal baclofen has been shown to be effective in reducing spasticity in patients with SCI, with significant improvements in Ashworth scores and activities of daily living performances 3, 4.
- Botulinum toxin type A has also been found to be effective in reducing focal spasticity and improving functional outcomes in patients with SCI 4, 7.
- The use of spinal cord stimulation and intrathecal baclofen therapy has been compared in a study, with both treatments showing significant improvements in spasticity index, but with different response durations 6.