The PF-SCS has 3 programs (P1, P2, P3) that can be used. At Visit 1, the study physician will
review the PF-SCS program that the participant has been using. This program is known as the
optimal program (OPP) and will be known as P1. The study physician will then designate the
other two programs (P2 and P3); one of them will be identical to the OPP (P1) and the other
program will be the LAP. The participant will be unaware if the LAP is assigned to P2 or P3.
At the end of Visit 1, the study physician will have the participant switch from P1 to the
LAP (P2 or P3). The participant will be reassured that if their pain returns after they
switch programs, they can immediately call the study physician and will be switched back to
the previous OPP (P1) without delay. The participants whose pain returns will be categorized
as Group 1. The physician will document the time that had elapsed before their pain returned.
This time will be considered as "carry over time" (COT) from PF-SCS. Only the study
physicians will be aware of the programming parameters for P2 and P3. The rest of the study
staff and participants will be blinded and will not be aware of the programming parameters
for P2 and P3.
The participants whose pain remains stable while on the LAP will be categorized as Group 2.
All participants will keep a daily diary for pain intensity, sleep and any other concerns
that may arise related to the change of program.
At the end of Visit 1, a member of the study team will schedule Visit 2, between 14 to 28
days from Visit 1.
Phone call: A study physician will call subjects between 7-14 days after Visit 1. Group 1
participants will be asked to switch to the LAP (P2 or P3) before Visit 2. To minimize the
duration of the LAP, Visit 2 will be scheduled within six hours from the end of COT. The
Group 2 participants will attend Visit 2 without changing their LAP.
At Visit 2, participants will fill out questionnaires on pain intensity, sleep, activities
and global impression. A blinded study staff will perform QST on the subject. At the end of
Visit 2, Group 1 participants will be instructed to go back to the OPP (P1). At the end of
Visit 2, Group 2 will be allowed to switch back to the OPP (P1).
The investigators will use quantitative sensory testing (QST) as a tool to objectively
quantify the impact of SCS on heat pain threshold, heat pain tolerance and wind-up over the
painful area and compare this with a non-painful area in each subject. QST will be performed
at Visit 1 and Visit 2.