Medications for Muscle Rigidity
Baclofen is the first-line medication for treating muscle rigidity, particularly for spasticity resulting from central nervous system conditions such as multiple sclerosis, spinal cord injuries, and other spinal cord diseases. 1, 2
First-Line Medications
Baclofen: Acts as a GABA-B receptor agonist, effective for severe spasticity resulting from central nervous system injury, demyelinating conditions, and other neuromuscular disorders. Start with a low dose and gradually increase to minimize side effects (dizziness, somnolence, gastrointestinal symptoms). Requires careful tapering when discontinuing after prolonged use. 1, 2
Tizanidine: Effective for chronic stroke patients with spasticity, improving both spasticity and pain without significant loss of motor strength. Has fewer muscle-weakening effects compared to baclofen but may cause sedation and dry mouth. 1, 3
Dantrolene: Has limited trial data but offers the benefit of no cognitive side effects. Acts directly on skeletal muscle rather than centrally. 1
Second-Line and Adjunctive Treatments
Cyclobenzaprine: Effective for acute skeletal muscle spasm. Similar in structure to amitriptyline with comparable side effect profile. The 5mg TID dosing regimen provides efficacy similar to 10mg TID with fewer sedative effects. 1, 4
Other muscle relaxants: Carisoprodol, chlorzoxazone, and methocarbamol may relieve skeletal muscle pain, but their effects are nonspecific and not directly related to muscle relaxation. 1
Benzodiazepines: Limited efficacy for persistent pain management but may be justified for muscle spasm, especially when anxiety, muscle spasm, and pain coexist. However, they have a high risk profile in older adults and are relatively contraindicated in stroke patients during recovery. 1
Advanced Interventions for Refractory Cases
Botulinum toxin: Consider for selected patients with disabling or painful spasticity or spasticity resulting in poor skin hygiene or decreased function. 1
Intrathecal baclofen: For chronic patients with severe spasticity resulting in pain, poor skin hygiene, or decreased function who are unresponsive to oral medications. Delivers baclofen directly to the cerebrospinal fluid at much lower doses than oral administration. 1, 5
Phenol/alcohol injections: Consider for selected patients with disabling or painful spasticity. 1
Special Considerations
For stroke patients: Tizanidine is specifically recommended for chronic stroke patients with spasticity. Diazepam and other benzodiazepines are not recommended during stroke recovery due to possible deleterious effects on recovery. 1
For muscle cramps in cirrhosis: Baclofen (10 mg/day, with weekly increases of 10 mg/day up to 30 mg/day) may be effective. Alternative options include orphenadrine and methocarbamol. 1
For older adults: Muscle relaxants may be associated with greater risk for falls. Use with caution and consider dose reductions. 1
Pitfalls and Caveats
Muscle relaxants should not be prescribed in the mistaken belief that they directly relieve muscle spasm; their effects are often nonspecific. 1
Many muscle relaxants carry significant risk of sedation, which can impair function and increase fall risk, particularly in older adults. 1
Discontinuation of baclofen after prolonged use requires slow tapering to prevent withdrawal symptoms, which can include delirium and seizures. 1
Carisoprodol has been removed from the European market due to concerns about drug abuse potential. 1
For conditions like stiff-man syndrome, baclofen has shown effectiveness in reducing rigidity, cramping, stiffness, and spasm, allowing previously bedridden patients to walk. 6