Understanding Post-Stroke Spasticity
Spasticity is a common condition after a stroke, characterized by a velocity-dependent increase in muscle tone, causing stiffness and involuntary muscle contractions [1.3.3, 1.4.2]. It occurs due to miscommunication between the brain and muscles following the neurological damage from a stroke [1.4.2]. The prevalence of post-stroke spasticity (PSS) is significant, affecting approximately 25.3% of all stroke patients [1.3.2]. This condition can interfere with mobility, daily activities, comfort, and hygiene, often leading to pain and joint contractures if not managed effectively [1.3.3]. Spasticity can be categorized as either focal (affecting a specific group of muscles, like in a hand or foot) or generalized (affecting multiple limbs) [1.2.2]. The choice of medication often depends on this classification.
Oral Medications for Generalized Spasticity
Oral antispasmodic medications are often used to treat generalized or widespread spasticity. These drugs work systemically, affecting the entire body rather than specific muscles [1.5.2]. While they can be effective, their use is often limited by side effects, such as drowsiness, weakness, and dizziness [1.5.1, 1.5.3].
Commonly Prescribed Oral Agents
- Baclofen (Lioresal®): Baclofen acts on the central nervous system to relax muscles by acting as a GABA-B agonist [1.2.2, 1.5.5]. It can reduce muscle spasms and tightness [1.5.3]. However, common side effects include drowsiness, confusion, weakness, and dizziness [1.7.2]. Abruptly stopping baclofen can lead to withdrawal symptoms [1.2.2].
- Tizanidine (Zanaflex®): This medication is a central alpha-2-adrenergic agonist that reduces spasticity by inhibiting nerve impulses without significantly lessening muscle strength [1.2.3, 1.5.5]. It is often used for short-term relief. Side effects can include dry mouth, sleepiness, and low blood pressure [1.7.2]. Liver function monitoring may be necessary [1.2.2].
- Dantrolene Sodium (Dantrium®): Unlike other oral agents, dantrolene works directly on the skeletal muscles by inhibiting the release of calcium, which is necessary for muscle contraction [1.2.2, 1.5.5]. It can cause generalized weakness, and due to a risk of hepatotoxicity, requires regular liver function monitoring [1.2.2, 1.7.1].
- Benzodiazepines (e.g., Diazepam/Valium®): These drugs act on the central nervous system to produce muscle relaxation [1.5.3]. Their use as a first-line treatment for spasticity is often limited due to significant side effects like sedation, cognitive impairment, and the potential for dependence [1.2.2, 1.7.2].
Injectable Medications for Focal Spasticity
For focal spasticity, where stiffness is confined to specific muscle groups, injectable treatments are preferred. These medications offer targeted relief with fewer systemic side effects compared to oral drugs [1.2.1, 1.2.3].
Botulinum Toxin (BoNT)
Botulinum toxin type A (BoNT-A), known by brand names like Botox®, Dysport®, and Xeomin®, is a first-line treatment for focal post-stroke spasticity [1.2.4, 1.4.3].
- Mechanism of Action: BoNT-A is a neurotoxin that blocks the release of acetylcholine at the neuromuscular junction, the chemical that signals muscles to contract [1.4.2, 1.7.1]. This results in temporary relaxation of the injected muscles.
- Efficacy and Use: It is highly effective at reducing muscle tone, improving passive function (like hygiene and dressing), and reducing pain associated with spasticity [1.2.2, 1.4.1]. The effects typically last for about three to four months, after which repeat injections are necessary [1.4.2, 1.7.1]. BoNT-A is most effective when combined with physical or occupational therapy, as the temporary muscle relaxation creates a window of opportunity to work on stretching and strengthening [1.4.2].
- Side Effects: Side effects are generally localized and may include pain at the injection site, and weakness in the injected muscle. Systemic side effects are rare [1.2.3, 1.7.1].
Other Injectable Options
- Phenol and Alcohol Neurolysis: These agents cause chemical denervation by destroying nerve fibers, providing longer-lasting relief than BoNT-A [1.2.2]. However, they are more technically challenging to administer and carry a higher risk of complications, including dysesthesia (abnormal sensation) and pain [1.2.1, 1.7.1]. They are typically considered when BoNT-A is not feasible [1.2.2].
Intrathecal Baclofen (ITB) Therapy
For severe, generalized spasticity that does not respond to oral medications or when their side effects are intolerable, Intrathecal Baclofen (ITB) therapy is an option [1.2.7].
How ITB Works
ITB therapy involves the surgical implantation of a small pump in the abdomen, which delivers liquid baclofen directly into the intrathecal space surrounding the spinal cord via a catheter [1.6.4]. Because the medication is delivered directly to the central nervous system, much lower doses are needed compared to oral baclofen, significantly reducing systemic side effects like drowsiness [1.6.2, 1.6.3]. Studies have shown that ITB therapy is superior to conventional oral medication for improving spasticity and pain [1.6.1, 1.6.5]. The pump's battery lasts for about seven years before needing replacement [1.6.4].
Medication Comparison Table
| Medication/Therapy | Type | Primary Use | Mechanism of Action | Common Side Effects |
|---|---|---|---|---|
| Baclofen (Oral) | Oral | Generalized Spasticity | GABA-B agonist in the CNS [1.2.2] | Drowsiness, weakness, dizziness, confusion [1.7.2] |
| Tizanidine | Oral | Generalized Spasticity | Alpha-2 adrenergic agonist in the CNS [1.2.2] | Dry mouth, sleepiness, low blood pressure [1.7.2] |
| Dantrolene | Oral | Generalized Spasticity | Acts directly on muscle, inhibits calcium release [1.2.2] | Generalized weakness, drowsiness, potential liver damage [1.7.1] |
| Botulinum Toxin | Injectable | Focal Spasticity | Blocks acetylcholine release at neuromuscular junction [1.7.1] | Injection site pain, muscle weakness in injected muscle [1.2.3] |
| Phenol/Alcohol | Injectable | Focal Spasticity | Chemical nerve destruction (neurolysis) [1.2.2] | Injection site pain, dysesthesia (abnormal sensation) [1.7.1] |
| Intrathecal Baclofen (ITB) | Pump | Severe Generalized Spasticity | Delivers baclofen directly to spinal fluid [1.6.4] | Pump/catheter malfunction, infection, headache [1.2.1, 1.6.2] |
Conclusion
The choice of medication for post-stroke spasticity is highly individualized, balancing efficacy with side effects and considering whether the spasticity is focal or generalized. For widespread spasticity, oral agents like baclofen and tizanidine are common starting points, though limited by systemic side effects [1.5.1]. For focal spasticity, botulinum toxin injections are the recommended first-line treatment, offering targeted relief that enhances the effectiveness of physical therapies [1.2.2, 1.4.3]. In cases of severe, refractory spasticity, intrathecal baclofen therapy provides a powerful alternative with fewer cognitive side effects than high-dose oral medications [1.6.3]. Effective management often involves a combination of these pharmacological treatments with a consistent rehabilitation program to maximize functional recovery. For more information, visit the American Stroke Association.
