Phantom limb pain is suprizingly resistant to treatment and some articles on the subject have concluded “put them on opioids – perhaps methadone”. Now come two different approaches to treating the leg version of this – memantine and pulsed radioifrequency.
Memantine:Anesth Analg. 2008 Oct;107(4):1377-9.
Profound pain reduction after induction of memantine treatment in two patients with severe phantom limb pain.
Hackworth RJ, Tokarz KA, Fowler IM, Wallace SC, Stedje-Larsen ET abstract
Memantine Titrated to 10 -15 mg BID along with gabapentin 900-1200 mg tid, amitriptyline 50-75 mg hs, celecoxib 200 mg BID, and decreasing doses of methadone. The adjunctive meds were eventually stopped.
Did mention that their were some double blind trials of memantine in phantom limb pains that “was unsuccessful at showing a benefit in already- established chronic PLP.7,13–15 However, other studies have shown that memantine had a significant pain reduction effect in a certain subset of amputees [ie early cases benefit]
Radiofrequency of sciatic nerve:
Clin J Pain. 2008 Oct;24(8):736-9.
Pulsed radiofrequency treatment of lower extremity phantom limb pain.
Wilkes D, Ganceres N, Solanki D, Hayes M. abstract
Case severe pain helped temporarily by sciatic nerve block. So they did the following peripheral nerve procedure:
“In an effort to extend the pain relief, pulsed radiofrequency treatment of the sciatic nerve was performed. We used the Baylis Medical pain management generator and a 100 mm active tip Sluijter-Mehta Cannulae (Integra-Radionics) needle. To locate the sciatic nerve, we used the sensory stimulation mode under voltage control. The factory set rate is 50 Hz with 1 ms pulse duration. The voltage was initially set to 1 volt and was decreased in 0.1 volt increments until sensory stimulation of the phantom limb was no longer felt at 0.2 mV. Then, 0.2 mL of 5% lidocaine was injected for patient comfort. We completed 2 cycles on auto pulse mode. The factory set parameters are the following: duration of 120 s; temperature of 42°C; pulse duration of 20 ms; and pulse rate of 2 pulse/s. A total of 20 mL of 0.25% bupivicaine and 40 mg kenolog was injected after the treatment. The patient reported complete pain relief. At the 1-month follow-up visit, she continued to report 0/10 pain.”
Comment – memantine does not seem to work until you get levels that have considerable side effects. The trick with it is to catch the patient early. The pulsed radiofrequency seemed an act of desperation that worked out. Lidocaine 5% also has neurolytic properties and kenalog reduces firing in neuromas – so it might be a team effort that silenced the nerve. Both these small series are miracles and we need more of those..