Baclofen Usage: Indications, Dosing, and Safety
Baclofen should be continued preoperatively including on the day of surgery, with oral formulations indicated for spasticity from multiple sclerosis and spinal cord diseases, while intrathecal baclofen is reserved for severe spasticity unresponsive to maximum oral therapy. 1
Indications
Oral Baclofen
Baclofen tablets are FDA-approved for alleviating signs and symptoms of spasticity from:
- Multiple sclerosis (particularly for flexor spasms, concomitant pain, clonus, and muscular rigidity)
- Spinal cord injuries and other spinal cord diseases
Critical exclusions: Baclofen is NOT indicated for skeletal muscle spasm from rheumatic disorders, and efficacy has not been established for stroke, cerebral palsy, or Parkinson's disease 2, 3
Intrathecal Baclofen
Reserved for patients with spasticity of spinal or cerebral origin who:
- Are unresponsive to maximum doses of oral baclofen, tizanidine, and/or dantrolene
- Experience intolerable side effects from oral medications 4, 5, 6
Approximately 25-30% of spinal cord injury and multiple sclerosis patients fail to respond to oral baclofen 5
Dosing Regimens
Oral Baclofen
- Initiation: Start at low doses and gradually titrate upward to minimize adverse effects 4
- Adverse effects threshold: Typically appear at doses >60 mg/day 5
- Efficacy: Open-label studies show improvement in 70-87% of patients for spasticity and 75-96% for spasms 4
Intrathecal Baclofen
Initial dosing:
- Average therapeutic/optimal dose: 230.6 μg/day (range 50-450 μg/day) 7
- Maintenance doses range from 22-1400 μg/day, with most patients adequately maintained on 90-703 μg/day 8
Dose escalation by etiology:
- Cerebral spasticity: Highest requirements
- At discharge: 102.66 μg
- 1 year: 402.29 μg
- 10 years: 578.74 μg
- Spinal spasticity:
- At discharge: 82.89 μg
- 1 year: 296.3 μg
- 10 years: 522.63 μg
- Multiple sclerosis:
- At discharge: 82.73 μg
- 1 year: 226.95 μg
- 10 years: 320.6 μg
The largest dose escalation occurs within the first year of ITB therapy 9
Dosing strategy: Use Ashworth score as an objective guide—do not increase baclofen dosage after Ashworth score reaches 1 7
Critical Safety Precautions
Perioperative Management
Never discontinue baclofen abruptly before surgery. Baclofen must be taken preoperatively including on the day of operation 1
Withdrawal Syndrome: Life-Threatening Emergency
Oral baclofen withdrawal symptoms include:
- Visual and auditory hallucinations
- Anxiety, agitation, delirium
- Fever, tremors, tachycardia
- Seizures 1
Intrathecal baclofen withdrawal is potentially fatal and presents with:
- High fever
- Altered mental status
- Rebound spasticity
- Muscle rigidity leading to rhabdomyolysis
- Multiorgan failure
- Death 1
Withdrawal typically emerges within 1-4 days after abrupt discontinuation 10. Rapid baclofen reinitiation consistently resolves withdrawal symptoms 10
For intrathecal baclofen: Perioperative management requires input from a specialist in this area 1
Adverse Effects
Oral baclofen (incidence 10-75%):
- Sedation/somnolence
- Excessive weakness
- Vertigo
- Psychological disturbances
- Nausea, dizziness, mental confusion 4, 6
Most adverse effects are dose-related, transient, and reversible. Treatment discontinuation due to intolerable effects ranges from 4-27% 5
Intrathecal baclofen complications (rare):
- Catheter-related: 8.8%
- Pump-related: 2.9%
- Drug tolerance: 5.9% 7
Toxicity
Baclofen toxicity commonly presents at doses ≥300 mg with:
- CNS depression (68%)
- Seizures (36%)
- Respiratory depression (21%)
- Mechanical ventilation required in ~54.5% of cases
Management is supportive, with full clinical recovery in 97.7% of cases and mortality generally low (0-4%) 10
Special Populations
Avoid or use with extreme caution in:
- Patients with hepatic or renal dysfunction (limited data suggest unnecessarily high risk) 4
- Elderly patients (increased risk of severe sedative and hypotensive effects)
- Patients with brain damage (higher risk of seizures, psychic symptoms, hyperthermia) 4
Intrathecal Baclofen: Additional Considerations
Advantages over oral route:
- Direct CSF administration bypasses blood-brain barrier
- Uses <1/100th the concentration of oral dosing
- Minimizes central side effects (drowsiness, confusion)
- Programmable continuous infusion allows dose titration throughout the day 5
Efficacy: >80% improvement in tone and >65% improvement in spasms 4
Contraindications for intrathecal catheter insertion:
- Anticoagulant therapy
- Coagulopathy
- Local or systemic infection
- Anatomical abnormality of the spine 5