Focal Pain Outcomes using Configurations Applied for Lateral Stimulation

Chronic intractable pain is often defined as pain persisting for at least 6
months which has not responded to conservative treatment(s). The pain may be
due to current or past nerve injury and can result in significant disability,
reduced work productivity, reduced quality of life, and significant cost burden.

Early treatments for chronic pain typically include over *the-counter and
prescription medications. Later treatments like physical therapy and
interventional pain procedures (e.g. intraspinal injections, vertebroplasty,
pulsed RF) are attempted, sometimes followed by chronic high dose opioids and
back surgery, if indicated.

If back surgery is unsuccessful in relieving the chronic pain, the patient can
be labeled as having failed back surgery syndrome (FBSS). Spinal cord
stimulation is an option in the well-selected patient with chronic low back
and/or leg pain. Such pain can lead to a number of co-morbidities, including
reduced health-related quality of life, reduced ability to engage in activities
of daily living, increased disability, increased emotional depression, and
weight gain due to the adoption of a sedentary lifestyle.

Spinal cord stimulation (SCS) is effective for chronic intractable pain
associated with a variety of conditions, including, but not limited to: FBSS,
complex regional pain syndrome, low back pain and leg pain.

SCS is a less invasive treatment option for FBSS but has generally been
reserved for patients who have failed multiple, and indeed all possible, repeat
operations. With SCS, an implanted pulse generator (IPG) delivers electrical
current to electrode(s) implanted in the epidural space. This electrical
current causes activation of nerves and can be programmed to direct
stimulation to the nerves innervating the painful location, resulting in a
reduction of the intensity of that pain.

Traditionally, SCS has relied on the understanding that to achieve pain relief,
dorsal column stimulation-induced paresthesia (perceptionbased stimulation) has
to be generated overlying the area of pain in order to successfully treat pain.
However, recent studies indicate that effective pain relief may be obtained by
employing stimulation without paresthesia (subperception based stimulation).

Also outcomes of another stimulation paradigm (burst-stimulation) without
paresthesia induction has been reported.

Lateral stimulation outcomes, where leads are placed laterally in the epidural
space to target nerve roots, have been previously reported for foot pain.

This study will evaluated different types of stimulation. Perception based and
subperception based spinal cord and nerve root stimulation is evaluated.

To evaluate Multiple Independent Current Control (MICC) perception and
sub-perception based programming at Dorsal Column (DC) targets and Dorsal Root
(DR) targets for focal foot, knee, or groin pain relief.

Multi-center, double blind randomized controlled cross-over study.

All participants will be implanted with 1 or 2 additional electrodes at the
nerve roots.

Main study cohort:
Subjects from the main study cohort will be randomized twice. First
randomization takes place before start of the perception based stimulation. A
second randomization will take pace before the start of the subperceptionbased
stimulation.

Main study cohort and substudy cohort:
Subjects will be asked to implement wash out periods for maximum 7 days.

Patients who receive the device are subject to the same risks as patients
outside of this study who receive the same or other similar commercial devices.
However, there are additional risks related to the implantation of up to 2
electrodes at the lower level of the spine compared with the implantation of
the electrodes at the standard level of the spine. In addition, there is also a
higher risk related to the number of electrodes implanted in the study (up to 4
electrodes) compared with the number of electrodes implanted as standard of
care (2 electrodes only).

During the study the patients will be treated with different types of
stimulation. Patients may find certain stimulation parameters to be less
effective than others at reducing their pain, and they might experience
stimulation-related side effects including, but not limited to, muscle spasm
and discomfort, which the physician will address as per standard of care.

This study is set up to collect data through questionnaires and diary. To
complete these questionnaires, patients may spend additional time at the
hospital compared to standard of care.

For those follow up visits where programming is performed and questionnaires
are completed, patients may spend up to 1,5 hours additional time at the
hospital. Patients may find it difficult, uncomfortable or tiresome to complete
study visits, the pain diary and/or questionnaires.

Considering the above burden and risks, the conduct of this study is justified.