Milnacipran for the drastic improvement of refractory pain in a patient without depressive symptoms: a case report

Dear Editor,

Milnacipran is a selective and potent dual serotonin and noradrenaline reuptake inhibitor. It has been reported that milnacipran is beneficial for the treatment of chronic pain [2] and fibromyalgia [5]. However, to our knowledge, drastic effectiveness of milnacipran for the treatment of refractory pain has not yet been reported. We present a patient with refractory pain who responded drastically to single-agent treatment with milnacipran despite a lack of depressive symptoms.

Mr. A, a 59-year-old man who had been suffering from a severe pain such as thrusting a wimble into his left lateral femoral region for 2 months, came to our outpatient clinic. Through X-ray of the femur, magnetic resonance imaging of the brain and the spinal cord, and a blood examination, however, his physical and neurological examinations were normal, and he had no abnormal findings causing his severe pain. His daily life was impaired extremely because nonsteroidal anti-inflammatory drugs and anticonvulsants were ineffective in his severe pain.

Mr. A had not received any prior psychiatric treatment and no past history of alcohol and substance abuse. After psychiatric interview with him, depression and dementia were excluded, and he was diagnosed with pain disorder according to DSM-IV criteria. We evaluated his severe pain in left lateral femoral region with visual analogue scale (0–100) [1]. His score on the VAS was 94. We prescribed 50 mg/day of milnacipran. After 2 weeks of his taking milnacipran, his severe pain was not alleviated and his VAS score was 90. After 4 weeks, he improved dramatically and his VAS score decreased from 90 to 38. We increased a dose of milnacipran to 100 mg/day. After 7 weeks of his taking milnacipran, his pain resulted in complete resolution, and his score on the VAS was 0. No adverse effects of milnacipran were observed.

Tricyclic antidepressants that have serotonin and noradrenaline reuptake inhibitor properties are used for the treatment and management of pain [3]. The mechanism of action is thought to modulate descending pain inhibitory pathways due to the inhibition of reuptake of serotonin and noradrenaline released predominantly in the raphe nucleus and the locus coeruleus of the brainstem [4]. Therefore milnacipran, a selective serotonin and noradrenaline reuptake inhibitor, have utility in the treatment of pain. Further studies are necessary to establish the efficacy of selective serotonin and noradrenaline reuptake inhibitors in the treatment and management of pain.