Is it reasonable for post-operative spine patients to be on baclofen (muscle relaxant) + cyclobenzaprine (muscle relaxant) concurrently?

Concurrent Use of Baclofen and Cyclobenzaprine in Post-Operative Spine Patients

This combination should generally be avoided in post-operative spine patients due to additive CNS depression risks and lack of evidence supporting dual muscle relaxant therapy, with the notable exception being patients on chronic baclofen who require continuation to prevent dangerous withdrawal. 1, 2

Key Safety Concerns with Combination Therapy

Increased Delirium Risk

• Postoperative muscle relaxant use (baclofen and/or cyclobenzaprine) doubles the risk of delirium in older adults undergoing lumbar fusion, with an incidence of 17.6% versus 7.9% in controls (hazard ratio 2.00,95% CI: 1.14-3.49). 2
• This risk is particularly concerning as both agents cause CNS depression, and their effects are additive when combined with opioids and other sedating medications commonly used perioperatively. 1

Additive Sedation and CNS Depression

• The Society for Perioperative Assessment and Quality Improvement (SPAQI) explicitly warns that "a consistent adverse effect of concern in the perioperative period is the potential for increased sedation when used concomitantly with opiates and/or other central nervous system depressants." 1
• Both baclofen and cyclobenzaprine are CNS depressants with overlapping side effect profiles including drowsiness, dizziness, and sedation. 1

When Baclofen Must Be Continued

Withdrawal Prevention

• Baclofen must be continued perioperatively in patients on chronic therapy to prevent potentially life-threatening withdrawal. 1
• Withdrawal symptoms include visual and auditory hallucinations, anxiety, agitation, delirium, fever, tremors, tachycardia, and seizures. 1
• Abrupt withdrawal of intrathecal baclofen can cause high fever, altered mental status, rebound spasticity, muscle rigidity leading to rhabdomyolysis, multiorgan failure, and death. 1
• SPAQI consensus recommendation: "Take preoperatively including the day of operation." 1

Cyclobenzaprine Considerations

Limited Postoperative Utility

• Cyclobenzaprine requires a 2-3 week taper when discontinued after chronic use to prevent withdrawal symptoms (malaise, nausea, headache). 3
• There is no high-quality evidence supporting cyclobenzaprine's efficacy specifically for post-spine surgery pain management. 1
• All muscle relaxant trials were 2 weeks or less in duration, indicating these agents should only be used short-term. 4

Preferred Alternatives

• If a single muscle relaxant is needed postoperatively and the patient is not already on chronic baclofen, tizanidine is the preferred choice based on mounting evidence for perioperative benefit including improved postoperative pain control, decreased opioid consumption, and hemodynamic stability. 1
• Tizanidine has the strongest evidence base among muscle relaxants for acute musculoskeletal pain (8 trials) and is recommended by the American College of Physicians as the first alternative to cyclobenzaprine. 4

Clinical Algorithm for Post-Operative Spine Patients

Patient Already on Chronic Baclofen

• Continue baclofen at home dose throughout perioperative period to prevent withdrawal. 1
• Do not add cyclobenzaprine due to additive CNS depression and increased delirium risk. 2
• If additional muscle relaxation is needed, optimize multimodal analgesia with gabapentin/pregabalin, COX inhibitors, and acetaminophen instead. 1

Patient Not on Chronic Muscle Relaxants

• Avoid initiating dual muscle relaxant therapy postoperatively. 2
• If muscle relaxation is deemed necessary, use a single agent (preferably tizanidine) for short-term use only (≤2 weeks). 1, 4
• Prioritize multimodal analgesia: pregabalin/gabapentin, COX inhibitors, acetaminophen, and judicious opioids. 1

Patient on Chronic Cyclobenzaprine

• Continue cyclobenzaprine to avoid withdrawal symptoms. 3
• Do not add baclofen due to lack of evidence for combination therapy and increased CNS depression risk. 2

Common Pitfalls to Avoid

• Do not assume muscle spasm requires muscle relaxant therapy - postoperative spasm does not necessarily represent a significant element of postoperative pain requiring pharmacologic intervention. 5
• Do not use muscle relaxants as first-line therapy when multimodal analgesia with gabapentinoids, NSAIDs, and acetaminophen may be more appropriate and safer. 1
• Do not abruptly discontinue baclofen in patients on chronic therapy, even if concerned about side effects - the withdrawal syndrome is far more dangerous than continuing the medication. 1
• Exercise particular caution in elderly patients (>65 years) who have substantially higher delirium risk with muscle relaxants. 2