Background: Phantom pain is present in more than 70% of amputees, and often progresses to chronic pain.1 Its control is challenging due to multiple somatic and neuropathic mechanisms, with no optimal pharmacological management.2 We present a case of difficult phantom pain control in spite of analgesic multimodal therapy to identify better approaches in the future.
 
Case report: A 23-year-old female, ASA III, 45kg, was proposed for left inter-scapular-thoracic amputation due to a humeral metastasis, with good pain control with transdermal fentanyl 75 µg/day. Pre-operatively, she expected the limb might not be amputated. She had a balanced general anaesthesia with fentanyl (3 µg/kg) and a ketamine infusion (4 µg/kg/min). Before limb removal, the supraclavicular brachial plexus was infiltrated with ropivacaine 0.75% (10mL). A perineural catheter was placed under direct visualization. Intraoperative analgesia included paracetamol 1g, metamizole 2g, ketorolac 30 mg and morphine 5 mg. She woke up referring severe (10/10) phantom pain, poorly (8/10) relieved after rescue analgesia with IV morphine and perineural ropivacaine 0.2%.
Post-operative multimodal analgesia was early initiated. Even though, she had persistent uncontrolled phantom pain, requiring therapeutic adjustments over several days, up to maximum doses of paracetamol 1g 4id, metamizol 1g 3id, duloxetine 30 mg bid, pregabalin 250 mg daily, ketamine infusion 9 µg/kg/min, ropivacaine 0.375% 10 mL boluses 6id, morphine PCA  2 mg/h with 1mg bolus. Non-pharmacological measures - psychological support and hypnosis, were started on postoperative (PO) day 8.
The first significant reduction in pain scores happened on PO day 10, (pain score<3), with downward therapy titration.
 
Discussion: Phantom pain is multifactorial but still poorly understood, and its treatment is often complex. Morphine, gabapentin and ketamine are evidence-based short term treatments.2 Pharmacological management is often not enough, as verified in our case. Perioperative psychological factors seem to have been determinant for our patient.
 
References
1. 	Warner NS, et al. Pain Pract. 2015;15(7):E76-E80.
2. 	Alviar M, et al. Cochrane Database Syst Rev Protoc. 2016;(1):1-52.

Learning points: Prevention and treatment of post-amputation pain with targeted interventions should remain a key goal for anaesthesiologists. Pre-emptive analgesia, pre-operative psychological support and alternative therapies such as hypnosis should be early adopted.


10 / Upper limb acute phantom pain - a case of difficult pain control