What is the initial treatment for phantom limb pain?

Initial Treatment for Phantom Limb Pain

The initial treatment for phantom limb pain should be gabapentin or pregabalin, which have demonstrated efficacy in reducing pain intensity compared to placebo. 1, 2

First-Line Pharmacological Options

• Gabapentin is recommended as first-line therapy, starting at 100-300 mg daily and gradually increasing to 900-3600 mg/day in divided doses 2, 3
• Pregabalin is an alternative first-line option with similar mechanism to gabapentin, starting at 25-50 mg/day in older adults and gradually increasing to 150-600 mg/day in divided doses 2
• In a randomized, double-blind, placebo-controlled study, gabapentin showed significantly greater pain intensity reduction compared to placebo after 6 weeks of treatment 3
• When combining results from studies, gabapentin shows favorable outcomes over placebo for pain relief (mean difference -1.16,95% confidence interval -1.94 to -0.38) 4

Alternative First-Line Options

• Tricyclic antidepressants (TCAs) like nortriptyline or desipramine can be considered as alternative first-line agents 1, 2
• Secondary amine TCAs are preferred over tertiary amines due to fewer anticholinergic side effects 2
• Serotonin-norepinephrine reuptake inhibitors (SNRIs) like duloxetine (60 mg daily) or venlafaxine (150-225 mg/day) are also effective alternatives 1, 2
• TCAs should be used with caution in patients with cardiac disease or ventricular conduction abnormalities, with dosages preferably kept below 100mg/day 1

Adjunctive Treatments

• Topical agents like lidocaine 5% patches may provide relief when applied to the residual limb for up to 12 hours daily 1, 2
• Topical combinations like amitriptyline 1-2% compounded with ketamine 0.5-5% have shown a 75% improvement rate when applied up to 3 times daily 1
• NMDA receptor antagonists like ketamine and dextromethorphan have shown analgesic effects in phantom limb pain, though memantine appears ineffective 4

Important Considerations and Monitoring

• Gabapentin's common adverse events include somnolence, dizziness, headache, and nausea 4
• Regular reassessment of pain, function, and side effects is essential, with an adequate trial of medication before considering alternatives 2
• Avoid inadequate dosing which can lead to treatment failures; ensure therapeutic levels are reached before concluding ineffectiveness 2
• Phantom limb pain occurs in up to 80% of amputees and must be differentiated from non-painful phantom phenomena and residual-limb pain 5

Non-Pharmacological Approaches

• Exercise therapy promotes systemic adaptation through reduction of inflammation and improvement of cardiovascular fitness 1
• Cognitive behavioral therapy helps address psychological aspects of chronic pain 1
• Avoid splinting of the residual limb as it may increase focus on the area, promote accessory muscle use, and lead to muscle deconditioning 1
• Transcutaneous electrical nerve stimulation (TENS) is a non-invasive option, although evidence is inconclusive 2

Refractory Cases

• For patients with inadequate response to first-line treatments, interventional procedures such as nerve blocks, spinal cord stimulation, or dorsal column stimulation can be considered 2
• Opioids may be considered for acute phantom limb pain or episodic exacerbations, but should be used cautiously due to risks of dependency, addiction, and hyperalgesia 1
• Morphine (oral and intravenous) has shown effectiveness in decreasing pain intensity in the short term, but with significant adverse events including constipation, sedation, and respiratory problems 4