Comparing patient's preference of dorsal column stimulation versus dorsal root ganglion stimulation in patients with complex regional pain syndrome confined to the knee

Complex regional pain syndrome is a collection of locally appearing painful
conditions following a trauma, which mainly occur in the feet or the hands and
exceed in both intensity and duration the expected clinical course of the
original trauma. The natural history of CRPS is not always positive and can
result in permanent disability. Our interest was drawn by a group of patients
with CRPS confined to the knee. Neurostimulation is an accepted, effective and
safe way for the treatment of chronic pain. Neurostimulation has already been
demonstrated as being effective as treatment for patients with CRPS. CRPS is
the second common indication for dorsal column stimulation (failed back surgery
being the first one). DCS has his limitations; it is rather nonspecific and
places like the knee are difficult to stimulate. In 2011 the first patients
received a dorsal root ganglion stimulation device as treatment for their
chronic neuropathic pain. Both stimulation devices require a test period; if
the patient has clinical significant pain relief during this test period, a
definitive implantation can be the next step.

Dorsal column stimulation and dorsal root ganglion stimulation are both proven
to be effective as treatment for chronic, neuropathic pain. We want to compare
patients preference of stimulation type in patients with chronic, neuropathic
pain due to CRPS confined to the knee.

The study consists of two phases. Patients will be screened based upon the
inclusion and exclusion criteria, consented and enrolled into the study. The
patients are included for both phases of the study. Fifteen patients will then
be assessed for baseline measurements of several secondary outcomes.

Phase 1.
Temporary Trial Stimulation. Patients will trial the two neurostimulation
systems during a period of 16 days. Day 1 will be the day when the intervention
takes place. Both types of stimulationleads will be implanted during the same
time, during the same procedure. Day 1-4 will be without any stimulation; in
this way the patient is given some time to recover from the intervention. Days
5-9 and days 12-16 will be the days when one of each stimulation is active. A
randomisation based on a computer program takes place for each patient to
decide the order of stimulation. During days 10-11 there will be a wash out
period; a period without any stimulation. Every patient need to document the
pain relief and satisfaction for each stimulation during phase 1 in a patient
diary. If the eligible patients agrees to have a definitive implantation, they
will undergo another surgical procedure following phase 1 within two weeks, in
which the definitive neurostimulation will be fully implanted.
Phase 2.
Long term Follow Up. During the long term follow up the patients will be
visiting the department at one, three, six and twelve months after the implant.
In case a patient was a *double-negative*, he/she will still be visiting the
department the same time as the implanted patients. The double-negatives will
than serve as controls. During the visits at 3 and 12 months after implant the
patient will undergo the same measurements as they already did at baseline. At
the 6 months after implant visit, the patient will undergo a FDG/PET CT scan
for the second time, to see if the stimulation has any effect on the
inflammation.

Placement of two different types of neurostimulation leads: corsal column
stimulation leads and dorsal root ganglion stimulation leads. After the trial
period of 16 days, the patient will undergo a next operation within one week
for definitive placement of the neurostimulator.

The potential benefits of the therapy include significant pain relief,
increased quality of life, increased function, and reduced medicinal intake for
pain management. Both neurostimulation devices are usual standard care in
reducing chronic pain. The possibility of trying both systems, in randomised
order, in the same patient, before choosing which stimulation will be implanted
after clinically relevant pain relief is not usual standard care. The leads
will be placed during the same procedure, at the same time. No additional risks
are expected. During the trial period the patients will have to visit the
Erasmus MC two times extra; during this visit one system will be turned off and
the other one will be turned on. The FDG/PET-CT scan will be performed with
radioactive load, but the amounts are negligible.