Background Complex regional pain syndrome (CRPS) is characterized by intense pain and loss of
function, and associated with motor, trophic, sudomotor, and/or vasomotor changes of the
affected extremity. CRPS of the upper extremity is seen frequently in our electrodiagnostic,
neurology, and musculoskeletal clinics and occurs in up to one-third of patients who have
undergone common surgical procedures, such as carpal tunnel release or release of Dupuytren's
contracture. To date, there is a limited understanding of the underlying pathophysiology of
CRPS. As a consequence, few effective treatment options are available.
Peripheral nerve blocks have proven to be successful in reducing pain for several
musculoskeletal and neurologic conditions. These blocks could be an opportunity for blocking
somatic and autonomic sensory fibers that are thought to contribute to CRPS. In a small
exploratory study, we found that peripheral nerve blocks in the upper extremity
(suprascapular and median nerves) resulted in a 56% and 37% pain reduction in the shoulder
and hand two weeks after injection, respectively, and were well-tolerated in patients with
CRPS. While this was highly encouraging, large randomized placebo-controlled trials (RCTs)
are necessary to demonstrate effectiveness and safety of nerve blocks for this population
before this treatment is accepted into clinical practice. This proposal aims to demonstrate
the feasibility of performing such a RCT.
Objective To evaluate the feasibility of performing a placebo-controlled RCT assessing the
efficacy and safety of peripheral nerve blocks (suprascapular, median, and ulnar nerves) for
reducing pain in patients with CRPS. This is a phase IV feasibility study that will test the
critical elements necessary for performing a RCT.
Methods We will recruit participants (≥18 years old) from The Ottawa Hospital, Bruyère
Continuing Care (Elisabeth Bruyère Hospital, St-Vincent Hospital), and Providence Care
Hospital (Kingston, ON), meeting the well-established clinical Budapest criteria for upper
extremity CRPS and having a visual analog scale (VAS) pain score of at least 40 mm (to avoid
flooring effect). Participants will be block-randomized by the Ottawa Methods Centre to
receive injections of either A) intervention (suprascapular, median, and ulnar nerves) with
bupivacaine and triamcinolone acetonide, or B) placebo (saline). All participants will
receive standard care for CRPS.
Feasibility outcomes will focus on crucial methodologic aspects for the future RCT,
including: (1) level of recruitment, (2) rate of acceptance from eligible patients to the
randomization procedure, (3) blinding efficacy, (4) degree of patient retention, (5) rate of
data completion, and (6) rate of adverse events for both the placebo and intervention groups.
Outcome measures will be evaluated within 1 hour, 2 weeks, 6 weeks, and 3 months
post-injection.