Prediction of Inter-individual Differences in the Response to Morphine Versus Milnacipran in Patients With Sciatica

Prediction of Inter-individual Differences in the Response to Morphine by Psychophysical Assessment of Pain Enhancing and Inhibiting Mechanisms in Patients With Chronic Neuropathic Pain

Clinical, psychophysical, behavioral or genetic factor will predict the response to opioid treatment in patients with chronic neuropathic pain.

Inclusion Criteria:

1. Patients with moderate to severe chronic neuropathic pain or patients with radiculitis between 18 and 75 years of age.

2. Candidates for chronic opioid therapy for nonmalignant pain as determined by treating physician.

3. Patients treated with non-opioid analgetics, anti- inflammatory drugs or low opioid dosage (< 30 mg of oral morphine-equivalents per day).

4. Ability to understand the purpose and instructions of the study and to sign an informed consent.

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   Exclusion Criteria:

1.Diabetic Neuropathy 2.Pain in upper limbs 3.Receiving anti- depressants and/or anticonvulsants 4.Pregnant women 5.Inability to comply with study protocol. 6.Allergy to Opioids 7.A diagnosis of Raynaud's Syndrome 8.History of substance abuse

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