Inclusion Criteria:

• Each patient must have chronic severe pain of malignant or nonmalignant etiology with inadequate pain relief from or intolerance to conventional therapy.
• Each patient must have a predicted life expectancy of greater than or equal to 6 weeks relative to baseline.
• Each patient must be able to respond to the Visual Analog Scale of Pain Intensity (VASPI).
• Each patient must have an implanted programmable SynchroMed infusion device or a CADD-Micro external programmable infusion device and spinal catheter (hereafter "IT pump and spinal catheter") prior to enrollment into this trial. (If a patient has an external pump, the Investigator must ensure that the patient is at a low risk for infection and that the patient is capable of maintaining good personal hygiene. The Investigator must have demonstrated the ability to successfully manage patients with external pumps prior to enrolling a patient in this trial.)
• Each patient must be at least 18 years of age.
• Each patient must be competent to give written informed consent and has given written informed consent prior to performance of any study-related procedures. Reasonable accommodation of visually impaired patients will be allowed.
• Each patient is willing and able to comply with the protocol requirements.
• Each female patient of childbearing potential must agree to use adequate contraceptive methods while on PRIALT as determined by the Investigator.

Exclusion Criteria:

• Presence of pregnancy or lactation.
• Participation in another investigational drug or device trial within the preceding 30 days.
• Presence of known hypersensitivity to PRIALT or any of its components.
• Presence of any contraindication to continued IT therapy (for example, infection at the pump or catheter externalization site, uncontrolled bleeding diathesis, spinal canal obstruction that impairs cerebrospinal fluid [CSF] circulation, or patient and caregiver inability to manage and protect the IT pump and spinal catheter system and return for clinic follow up visits).
• Presence of any condition (for example, psychosis, severe depression or suicidal ideation, homicidality, somatization disorder, active substance abuse, cognitive deficits, dementia or other serious medical or psychiatric condition) that in the Investigator's opinion precludes the patient's ability to participate in this study.