Spinal cord stimulation as treatment for complex regional pain syndrome should be considered earlier than last resort therapy

The complex regional pain syndrome

Complex regional pain syndrome (CRPS) is the current consensus-derived name for a syndrome usually triggered by limb trauma. Required elements include prolonged, disproportionate distal-limb pain and microvascular dysregulation (e.g., edema or color changes) or altered sweating. CRPS-II (formerly "causalgia") describes patients with identified nerve injuries. CRPS-I (formerly "reflex sympathetic dystrophy") describes most patients who lack evidence of specific nerve injuries. Diagnosis is clinical and the pathophysiology involves combinations of small-fiber axonopathy, microvasculopathy, inflammation, and brain plasticity/sensitization. Females have much higher risk and workplace accidents are a well-recognized cause. Inflammation and dysimmunity, perhaps facilitated by injury to the blood-nerve barrier, may contribute. Most patients, particularly the young, recover gradually, but treatment can speed healing. Evidence of efficacy is strongest for rehabilitation therapies (e.g., graded-motor imagery), neuropathic pain medications, and electric stimulation of the spinal cord, injured nerve, or motor cortex. Investigational treatments include ketamine, botulinum toxin, immunoglobulins, and transcranial neuromodulation. Nonrecovering patients should be re-evaluated for neurosurgically treatable causal lesions (nerve entrapment, impingement, infections, or tumors) and treatable potentiating medical conditions, including polyneuropathy and circulatory insufficiency. Earlier impressions that CRPS represents malingering or psychosomatic illness have been replaced by evidence that CRPS is a rare complication of limb injury in biologically susceptible individuals.

Immediate Return to Ambulation and Improved Functional Capacity for Rehabilitation in Complex Regional Pain Syndrome following Early Implantation of a Spinal Cord Stimulation System

Complex regional pain syndrome (CRPS) is a neuropathic pain condition that is characterized by vasomotor, sensory, sudomotor, and motor symptoms. Spinal cord stimulation (SCS) has been successfully utilized for the treatment of pain refractory to conventional therapies. We present a case of a previously highly functioning 54-year-old female who developed a rarely reported case of idiopathic CRPS of the right ankle which spontaneously occurred four months after an uncomplicated anterior cervical disc fusion. This condition resulted in severe pain and functional impairment that was unresponsive to pharmacological management. The patient's rehabilitation was severely stymied by her excruciating pain. However, with the initiation of spinal cord stimulation, her pain was adequately controlled allowing for progression to full unassisted ambulation, advancing functional capacity, and improving quality of life. This case report supports the concept that rapid progression to neuromodulation, rather than delays that occur due to attempts at serial sympathetic blocks, may better control symptoms leading allowing for a more meaningful recovery.

Spinal cord stimulation for neuropathic pain: current perspectives

Neuropathic pain constitutes a significant portion of chronic pain. Patients with neuropathic pain are usually more heavily burdened than patients with nociceptive pain. They suffer more often from insomnia, anxiety, and depression. Moreover, analgesic medication often has an insufficient effect on neuropathic pain. Spinal cord stimulation constitutes a therapy alternative that, to date, remains underused. In the last 10 to 15 years, it has undergone constant technical advancement. This review gives an overview of the present practice of spinal cord stimulation for chronic neuropathic pain and current developments such as high-frequency stimulation and peripheral nerve field stimulation.

New horizons in neuromodulation

Electrical stimulation of the nervous system is a method used for several centuries which just in the past decades received wide recognition as an effective and safe modality in the management of neuropathic pain and other maladies. Explosion of new technologies and discovery of new neuromodulation targets are two parallel and interconnected processes. Using a paraphrase from the famous novel of Samuel Sham, The House of God, one can say that there is no nervous tissue in the human body that cannot be reached with a stimulating lead directed by a good strong arm. Neuromodulation devices are being used for the stimulation of the entire nervous system, from the cutaneous terminals to brain centers. Autonomic regulation is also subject to stimulation via implanted devices. Future research and development is tightly related to the process of discovery, experimental courage, and philosophical exploration of neurobehavioral mechanisms.

Refractory Chronic Pain Screening Tool (RCPST): a feasibility study to assess practicality and validity of identifying potential neurostimulation candidates

OBJECTIVE

An international panel of pain specialists (anesthesiology, neurology, neurosurgery, and psychology) and research methodologists developed a screening tool to identify patients who may be suitable for spinal cord stimulation (SCS)--the Refractory Chronic Pain Screening Tool (RCPST) prototype. We describe a feasibility study to explore practicality and validity of this prototype.

DESIGN

Consecutive outpatients were screened in two centers (United Kingdom and United States). Sixty chronic pain adults without satisfactory pain relief despite treatment were assessed using RCPST (by pain specialist without expertise in neurostimulation) and then evaluated by two pain specialists experienced in SCS implantation and management to determine whether the patient should be referred for SCS. To maintain blinding, the participating physicians did not inform each other or the patient of assessment outcome. Sensitivity and specificity of the RCPST prototype were calculated using implanters' judgment as "gold standard."

RESULTS

The average age of patients was 47.7 years; 53% were female. Fifty-seven patients completed the study (one withdrew consent, two lost to follow-up). The pain specialists agreed the prototype was easy to use and took <10 minutes to complete. Implanter agreement was moderate (Kappa: 0.63, 95% confidence interval: 0.35-0.91). The prototype had low sensitivity (40%, 19-61%) and moderate specificity (78%, 65-92%). Using the same questionnaire with a modified decision algorithm, new prototypes were generated with range of high sensitivity (80-100%) and specificity (89-97%) values.

CONCLUSIONS

The RCPST aims to identify patients that should be referred for consideration for neurostimulation. The final implant decision requires appropriate neurological diagnostic workup, psychological assessment, and trial stimulation. RCPST was considered practical for routine clinical practice and contained appropriate questions. Sensitivity needs to be improved. A future study should select and validate the ideal RCPST prototype.