Intrathecal Bolus Doses of Ziconotide

Inclusion Criteria: * Patient, at least 18 years of age * suffering from severe chronic (≥ 6 months) pain, who has failed on conventional pharmacological treatment * only patients with peripheral neuropathic pain or central neuropathic pain, due to trauma or surgery, will be included * Average usual VASPI last week ≥ 40 mm * Patient capable of judgment, i.e. able to understand information regarding the drug, the mode of administration and evaluation of efficacy and side effects Signed informed consent Exclusion Criteria: * Limited life expectancy (investigator's judgement) * Intrathecal chemotherapy * Known or suspected intracranial hypertension * Known liver or kidney disease, defined as ASAT, ALAT, Total Bilirubin, ALP or S- Creatinine \> 1.2 x ULN * Advanced cardio-pulmonary disease (investigator's judgment) * Ongoing infection, whether systemically or locally in the lumbar area * Coagulopathy (including medication with warfarin, clopidogrel and heparin) * Allergy to ziconotide or any of the excipients in the ziconotide vial * History of psychiatric disorders which in the investigator's opinion would put the patient at risk * Pregnant or lactating woman. * Menstruating women must use an effective contraceptive method (contraceptive pill or intrauterine spiral) during the trial period