What is the first‑line oral muscle relaxant for a spasticity‑induced contracted limb?

First-Line Oral Muscle Relaxant for Spasticity-Induced Contracted Limb

For a contracted limb caused by spasticity, oral baclofen is the first-line medication, starting at 5-10 mg/day and titrating slowly to a typical target dose of 30-80 mg/day divided into 3-4 doses. 1, 2

Treatment Algorithm

Step 1: Non-Pharmacological Interventions First

• Always initiate antispastic positioning, range of motion exercises, stretching, splinting, and serial casting before or alongside any medication. 1, 2, 3
• These foundational interventions should be performed several times daily and continued regardless of medication choice. 2, 3

Step 2: Oral Baclofen as First-Line Pharmacological Treatment

• Baclofen is FDA-approved and guideline-recommended specifically for spasticity causing pain, poor skin hygiene, or decreased function. 1, 2
• Start at 5-10 mg/day and titrate slowly every 2-5 weeks to minimize side effects (sedation, weakness, dizziness). 1, 4
• Target dose is typically 30-80 mg/day divided into 3-4 doses. 1, 2
• Allow 4-8 weeks at maximum tolerated dose before declaring treatment failure. 1

Step 3: Consider Focal vs. Generalized Spasticity

• If the contracture is focal (affecting specific muscles like hand or ankle), botulinum toxin injections are actually preferred over oral baclofen as first-line pharmacological treatment. 1, 3
• For generalized spasticity affecting multiple limbs, oral baclofen remains the appropriate first choice. 2, 3

Step 4: Alternative Oral Agents

If baclofen causes intolerable side effects or is ineffective:

• Tizanidine has equivalent efficacy to baclofen but better tolerability, particularly less weakness. 1, 5
• Dantrolene is another FDA-approved alternative for generalized spasticity. 2, 3

Step 5: Advanced Interventions for Refractory Cases

• Intrathecal baclofen via implanted pump is indicated for severe spasticity unresponsive to maximum oral doses, with >80% of patients showing improvement in muscle tone. 1, 6
• Neurosurgical procedures (selective dorsal rhizotomy) are last-resort options. 1, 2

Critical Safety Warnings

Absolute Contraindications and Precautions

• Never abruptly discontinue baclofen in long-term users—taper slowly over weeks to avoid life-threatening withdrawal (seizures, hallucinations, hyperthermia, death). 1
• Avoid benzodiazepines (diazepam) during stroke recovery as they have deleterious effects on neurological recovery. 1, 2, 3
• Use extreme caution and reduce doses in renal impairment (start at 5 mg/day) due to renal clearance and risk of CNS toxicity. 1
• Use caution in elderly patients and those with hepatic dysfunction due to increased CNS effects. 1

Common Adverse Effects

• Sedation, excessive weakness, dizziness, and mental confusion occur in 25-75% of patients. 5, 7
• Most adverse effects are dose-related, transient, and reversible. 5
• Baclofen may worsen obstructive sleep apnea by promoting upper airway collapse. 1

Evidence Quality Considerations

The American Heart Association, American Academy of Neurology, and American Stroke Association all consistently recommend baclofen as a guideline-supported first-line oral agent for generalized spasticity. 1, 2, 3 However, the evidence distinguishes between focal and generalized spasticity—botulinum toxin is superior for focal contractures affecting specific muscle groups. 1, 3 Open-label studies show 70-87% of patients improve with oral baclofen, though controlled trials demonstrate only modest superiority over placebo. 5, 7