Efficacy and Safety of Pregabalin in Treatment of Neuropathic Pain in Patients With Idiopathic Small Fiber Neuropathy

Inclusion Criteria: * Subjects with idiopathic predominate-small fiber neuropathy * Subject must have chronic peripheral neuropathic pain for more than 3 months * A score \>3 and \<8 on Pain intensity scale for pain in prior week at first visit; * Show increase in pain intensity scores during the wash off period; * Age older than 18 years; Exclusion Criteria: * Subjects with large-fiber predominant neuropathy * Subjects with HIV infection, trigeminal neuralgia (TGN), toxic neuropathy (e.g. chemotherapy exposure), paraneoplastic neuropathy, mono-gammopathy, inflammatory neuropathy, celiac disease, systemic lupus, peripheral vascular disease, connective tissue disorders, hepatitis C, Fabry disease, and diabetes; * Subjects with uncontrolled thyroid or B12 disorders * Subjects with Complex Regional Pain Syndrome * Allergy to Pregabalin * Subjects at risk of suicide or self harm * Subjects with any clinically unstable cardiovascular, hematological, autoimmune, endocrine, renal, hepatic, renal, respiratory, or gastrointestinal disease; epilepsy, symptomatic peripheral vascular disease including intermittent claudication, pernicious anemia, untreated hypothyroidism, venous insufficiency, or spinal stenosis. * History of known analgesic, alcohol or illicit drug abuse within 12 months of first visit; * Pregnant females; breastfeeding females.