Baclofen in Spastic Paralysis: Dosing and Role
Baclofen is primarily indicated for the alleviation of signs and symptoms of spasticity resulting from multiple sclerosis and spinal cord diseases, with oral dosing starting at 5mg TID and gradually increasing to 20-80mg daily, while intrathecal baclofen is reserved for severe, refractory spasticity at doses of 50-800 micrograms/day. 1, 2
Mechanism of Action
- Baclofen is a GABA-B receptor agonist that acts at the spinal cord level to inhibit the release of excitatory neurotransmitters responsible for spasticity 2
- It is particularly effective for relieving flexor spasms, clonus, muscular rigidity, and associated pain 1
Oral Baclofen
Indications
- First-line for spasticity resulting from multiple sclerosis
- Valuable in patients with spinal cord injuries and other spinal cord diseases
- Not indicated for:
- Skeletal muscle spasm from rheumatic disorders
- Stroke (efficacy not established)
- Cerebral palsy (efficacy not established)
- Parkinson's disease (efficacy not established) 1
Dosing Protocol
- Initial dose: 5mg three times daily
- Titration: Gradually increase by 5mg per dose every 3 days
- Typical effective range: 20-80mg daily in divided doses
- Maximum dose: Generally not exceeding 80mg daily (higher doses may be required in some cases but increase risk of side effects)
- Discontinuation: Must be tapered gradually to prevent withdrawal syndrome, which can be life-threatening 2
Intrathecal Baclofen
Indications
- Severe spasticity unresponsive to oral medications
- Particularly effective for spinal spasticity (multiple sclerosis, spinal cord injury)
- May benefit selected patients with cerebral palsy 2, 3
Dosing Protocol
- Test dose: 50-100 micrograms via lumbar puncture to confirm efficacy
- Implantation: Programmable pump system surgically implanted if test dose successful
- Initial dose: Typically 50-100 micrograms/day
- Maintenance dose: 27-800 micrograms/day (individualized based on response)
- Monitoring: Regular assessment and dose adjustments as needed 4, 5
Efficacy
- Significantly reduces muscle tone (Ashworth scores typically decrease from ~3.8 to ~1.5)
- Reduces spasms (mean scores decrease from ~3.5 to ~1.2)
- Improves upper extremity function in some patients
- Enhances activities of daily living 4, 2
Clinical Considerations and Cautions
Side Effects
- Oral baclofen: Sedation, cognitive impairment, weakness, dizziness
- Intrathecal baclofen: Decreased consciousness, drowsiness, confusion (particularly in younger patients) 6, 5
Monitoring
- Regular assessment of therapeutic response
- Vigilance for side effects, especially sedation
- For intrathecal therapy: pump function, catheter integrity, infection signs 4
Potential Complications
- Tolerance: Some patients (approximately 15%) may develop tolerance requiring escalating doses
- Withdrawal syndrome: Abrupt discontinuation can lead to life-threatening withdrawal
- Device-related: Catheter malfunction (
20%), infection requiring pump removal (5%) 3, 2
Treatment Failures
- Poor response may occur in some forms of spasticity
- Limited effect on athetosis in cerebral palsy
- Less impact on spasticity in stroke compared to other conditions 2
Comparative Efficacy
- Intrathecal administration achieves much higher CSF levels than oral administration
- Intrathecal baclofen is more effective than other intrathecally administered drugs (e.g., morphine, midazolam) for reducing spasticity 6
- Tizanidine may be preferred for post-stroke spasticity with pain 2
By understanding the appropriate indications, dosing protocols, and potential complications of baclofen therapy, clinicians can optimize outcomes for patients with spastic paralysis while minimizing adverse effects.