Percutaneous trial case for complex regional pain syndrome

Scenario

A 45-year-old female with a 2-year history of right lower extremity complex regional pain syndrome I (CRPS I) is referred by a community neurologist for a trial of spinal cord stimulation (SCS). The patient incurred an Achilles tendon injury at work that necessitated surgical repair. Several weeks after the surgery, the patient continued to have excessive burning pain with associated swelling, persistent erythema, and piercing cold dysesthesias that encompassed the entire lower extremity involving the foot and calf up to the knee. She did extensive casting followed by physical therapy. Despite adequate healing, there is no real improvement in the intensity and nature of her pain. The extremity was well perfused, and the lack of an explanation for persistent pain led to a diagnostic triple phase bone scan that supported the suspected diagnosis of CRPS. She then received a series of lumbar sympathetic blocks as well as medications in conjunction with physical therapy. The patient derived very short-term relief and complained of poor sleep. In addition, allodynia of the right lower limb meant that she could not even have a bed sheet contact it.

• Variation : The patient has no diagnostic tests before referral -- The diagnosis of CRPS continues to be based on clinical criteria (so-called Budapest Criteria). For medical and as well as future legal matters that not uncommonly follow these patients, it is important to have documented diagnostic criteria that support the CRPS diagnosis. Diagnostic tests such as inflammatory markers, X-rays, magnetic resonance imaging studies, and bone scans can help exclude other causes and support the diagnosis. Once there is a region (nondermatomal) of the extremity that is affected on clinical assessment, then CRPS is evaluated using the following criteria: sensory alterations (allodynia, hyperalgesia), vasomotor (temperature difference of 1°C, color variation), sudomotor/edematous changes, and motor/trophic alterations (ankylosing of joints, atrophy, dystonia). These criteria are applied in terms of symptomatic complaints in which case there must be three of the categories fulfilled as well as two distinct categories on physical examination. Not uncommonly, with progression of time, the physical findings can diminish in many patients, but others can remain with chronic edema, lower limb atrophy, and loss of range of motion in the toes and ankle. Patients with CRPS, who present for SCS therapy, usually do so after 1–2 years of poorly managed symptoms.

• Variation : There was no response to lumbar sympathetic blockade -- The response to sympathetic blockade that eliminates a substantial component of the patient's pain implies sympathetically mediated pain (SMP). Sympathetic blocks are well established for treatment of the acute phase of CRPS and can help facilitate rehabilitation. Once CRPS establishes a more persistent state, the analgesic effects of the block are not uncommonly short-lived. SCS has become well established as a therapy that can modulate the sympathetic nervous system in both preclinical as well as clinical studies. SCS is therefore highly likely to alleviate the pain in a patient with SMP, but because of the multiple mechanisms of action involved in SCS, the therapy can also have a significant chance of success in sympathetically independent pain.

• Variation : The patient had a trial of gabapentin only -- The management of symptoms using medications for CRPS continues to evolve. The use of membrane-stabilizing agents such as gabapentin, pregabalin, or topiramate may offer relief of neuropathic symptoms. Not uncommonly, the relief is modest, and antidepressant medications in the categories of serotonin and norepinephrine reuptake inhibitors or tricyclics are used to enhance analgesia. Antiinflammatory agents may help with the ankylosing component of the syndrome. Corticosteroids are of use only early in the syndrome. Atypical opioids such as tramadol or tapentadol are not well studied in CRPS but can offer analgesia. The current trend is to avoid traditional mu agonist opioids or at least maintain low dose. Finally, the use of ketamine infusions has been established in randomized control trials to offer short-term relief, but insurance coverage is not uncommonly an issue.

• Variation : In addition, the patient has complaints of right lower extremity weakness, stiffness, and spasm -- Patients with CRPS frequently have additional symptomatic complaints in the extremity that go beyond neuropathic pain and are not likely to be palliated by SCS. Therefore, a directed discussion with the patient on what SCS will likely treat is important before the trial as well as full implantation. The reversal of dystonia, tremors, muscle spasm, and joint ankylosis are not reliably responsive to SCS therapy. Alleviation of the neuropathic component can still play a major role to facilitate rehabilitation that may permit more symptomatic control of the trophic changes. Additionally, patients with CRPS may have multiple systemic complaints that are not ameliorated or caused by SCS therapy but do nonetheless impact the quality of life for these individuals. Multiple organ systems may be affected that can cause neurocardiogenic syncope, incontinence, feeling of shortness of breath, dysphagia, irritable bowel syndrome, and reflux disease.

• Variation : The patient has high levels of anxiety -- CRPS is a very distressing syndrome that carries a very high disability rate in the chronic state. Patients lose a great deal of autonomy and self-worth that can exacerbate or lead to worsening anxiety and depressive states. In a multidisciplinary pain center, these patients are referred to a psychologist who specializes in the treatment of these conditions as they relate to CRPS. The key issue is to manage the psychopathology to a level that will permit a trial of SCS therapy. A trial of SCS in the presence of high anxiety levels is often indeterminate and confounded by procedural pain and preoccupation with multiple somatic complaints with the inability to focus on the temporary trial. There is a steep learning curve of the technology, and patients need to be able to familiarize themselves with the therapy to maximize their chances for relief. The patient may, out of pure desperation, demand the therapy even if the trial was of unclear benefit.