Background/AimsAcidic saline injections produce mechanical hyperresponsiveness in male Sprague-Dawley rats. We investigated the effect of milnacipran in conjunction with tramadol on the pain threshold in an acidic saline animal model of pain.MethodsThe left gastrocnemius muscle of 20 male rats was injected with 100 µL of saline at pH 4.0 under brief isoflurane anesthesia on days 0 and 5. Rats administered acidic saline injections were separated into four study subgroups. After determining the pre-drug pain threshold, rats were injected intraperitoneally with one of the following regimens; saline, milnacipran alone (60 mg/kg), milnacipran (40 mg/kg) plus tramadol (20 mg/kg), or milnacipran (40 mg/kg) plus tramadol (40 mg/kg). Paw withdrawal in response to pressure was measured at 30 min, 120 min, and 5 days after injection. Nociceptive thresholds, expressed in grams, were measured with a Dynamic Plantar Aesthesiometer (Ugo Basile, Italy) by applying increasing pressure to the right or left hind paw until the rat withdrew the paw.ResultsA potent antihyperalgesic effect was observed when tramadol and milnacipran were used in combination (injected paw, p=0.001; contralateral paw, p=0.012). This finding was observed only at 30 min after the combination treatment.ConclusionsWe observed potentiation of the antihyperalgesic effect when milnacipran and tramadol were administered in combination in an animal model of fibromyalgia. Further research is required to determine the efficacy of various combination treatments in fibromyalgia in humans.

A 67-year-old man developed swelling of the right leg with inguinal and abdominal pain over a period of 5 days. Excisional biopsy of the left supraclavicular lymph nodes revealed the diffuse, large B cell type of malignant lymphoma. After chemotherapy, he complained of a tingling sensation and weakness in the left upper extremity, and then this progressed to quadriplegia. Electrodiagnostic testing demonstrated the characteristic findings of demyelination, which was consistent with Guillain-Barre syndrome (GBS). Non-Hodgkin's Lymphoma (NHL) leading to GBS, as was observed in the present case, suggests that physicians should be aware of GBS and non-Hodgkin's lymphoma as the full spectrum of these diseaseshas not been fully defined. (Korean J Hematol 2008;43:263-267.)