The Nalu Neurostimulation System is capable of delivering multiple therapy options to address patient needs. The study will confirm the efficacy, safety, comfort and compliance with the Nalu Neurostimulation System in adult subjects with chronic pain in the legs and back. Patients who have been diagnosed with failed back surgery syndrome (FBSS) and meet other study eligibility criteria will be enrolled in the study to receive the Nalu Neurostimulation System.

The study is a prospective, multi-center, open-label, single-arm clinical study with each subject serving as their own control. The study will confirm device efficacy, safety, comfort and compliance with the system.

Subjects who meet the protocol specified eligibility criteria and provide documented informed consent will be considered for study participation. There are three phases in the study: Screening/Baseline Phase, Trial Phase, Permanent Implant Phase. On confirmation of eligibility during the screening/baseline phase, subjects will enter the Trial Phase where they will undergo a trial with the Nalu Neurostimulation System. Trials will be done per standard clinical practice and per system IFU. Subjects receiving at least 50% reduction in their back pain, during the trial phase, will continue to the permanent implant phase.

Eligible subjects will receive the Nalu Neurostimulation System per standard surgical and medical practices and will be programmed for stimulation with one or more therapies to optimize pain reduction. All subjects receiving a permanent implant will be followed for 3-months post device activation. They will visit the clinic at 1 month and 3-months follow-up and programming, as required. Adverse Event data will also be collected to support a safety endpoint.

Multiple outcome domains will be captured throughout the study to confirm system performance and subject response to the device. These include Visual Analogue Scale (VAS) for pain, Numeric Rating Scales for pain, EQ-5D (QoL), the Oswestry Disability Index (ODI), PROMIS Sleep Disturbance SF, Beck's Depression Index (BDI), pain and paresthesia maps, pain and wearability diaries.

At study completion, subjects will return to standard clinical practice.

Inclusion Criteria:

1. Subject is between 21 and 80 years of age at enrollment.
2. Subject has chronic (defined as at least 6 months duration), intractable neuropathic pain of legs and/or back; any nociceptive pain must be less prominent than the neuropathic pain.
3. Subject's pain is unresponsive to conservative treatment options.
4. Subject has a VAS Score of at least 6 in the back and/or leg at screening.

Exclusion Criteria:

1. Subject currently has an active implantable medical device such as a drug pump, spinal cord stimulator, sacral nerve stimulator, deep brain stimulator, and/or cardiac pacemaker.
2. Subject has previously failed SCS therapy (either trial system evaluation or permanent implant).
3. Subject has had an ablative procedure directed at the spinal cord including the dorsal root entry zone (DREZ) or dorsal root ganglion (DRG).
4. Subject has pain in another anatomic region besides the leg(s) and back that would interfere with their ability to accurately report pain (e.g. hip joint pain).
5. Subject has a medical condition that would prevent them from participating in the current study per investigator's or medical monitor's judgment.