KETAMINE INFUSION AND CRPS

Ketamine is an anesthetic and a very potent analgesic medication that has shown positive results for the treatment of CRPS, fibromyalgia and severe depression among others. This medication has very serious side effects that can be ameliorated in the hands of a seasoned anesthesiologist. Few physicians offer this therapy because of the demanding work and monitoring required. Many patients travel several miles to get the treatment, with the subsequent monetary burden from lodging, flights, car rentals, etc.

CRPS (Complex regional pain syndrome) is a troubling and frequently intractable pain condition. It had different names in the past, but today is called CRPS. Complex because it has different presentations; Regional because typically involves an extremity; Pain because it is vital to the diagnosis; Syndrome because the pathophysiology is not very clear. CRPS usually follows an injury to a peripheral nerve (type II) or a trauma without obvious nerve damage (type I). It presents with a distinctive group of sensory, motor, and autonomic signs and symptoms, being pain the central feature. Patients also have symptoms like irritability, anxiety, sleep disturbances, tremors and nervousness. The most common cause are fractures (16%), sprain/strain (10-29%), surgery (3-24%). 1 out of 52 will develop CRPS in their lifetime with a female to male ratio 4:1.

The mechanism of the disease involves more than one aspect: neuropathic, immune and inflammatory. The neuropathic process is complex and has a sympathetic and a somatic component (sensory and motor) and can be peripheral or central. The immune process involves an autoimmune Ab (antibody) and alteration of the HLA expression and inflammation. The inflammatory aspect is evidenced by the increased levels of inflammatory factors.

Initially 3 stages were proposed, but today we know there is a very wide spectrum of the condition from patients with very mild symptoms to patients with severe symptoms. In most cases there is no progression of the disease, symptoms remain stable and may even improve. But in a 10% of patients the disease spreads to other extremities.

Diagnosis of CRPS is based on clinical criteria. No test has enough specificity and sensitivity to diagnose it. The latest proposed diagnosis is based in the Budapest criteria. It includes the absence of other conditions that explain the symptoms and the presence of sensory, vasomotor, sudomotor and motor/trophic signs and symptoms. The response to sympathetic block does NOT make a diagnosis.

Treatment includes PT (not tolerated by all); interventions like sympathetic blocks, IVRA, catheter techniques, spinal/peripheral cord stimulator, IT pumps, motor cortex stimulation; psychological interventions; and medications like antiepileptics, opioids, NSAIDs, antidepressants, α-1 blockers, α-2 agonists, NMDA antagonists (Ketamine), bisphosphonates, TNF-α antibodies, oral prednisolone, among others.

Ketamine infusion has been studied in the course of CRPS and the analysis of these studies suggests that the prolonged infusions produce reductions in pain that persist for weeks with evidence of a substantial (>50%) analgesic effect that could be useful in refractory cases of CRPS. The beneficial effects of the ketamine infusion on pain scores are lost after a few weeks, which must be set against the chronicity of the disease. Thus, repeated dosing would be needed for patients with CRPS. For these parenteral infusion protocols a very close observation is required and should be performed by a skilled anesthesiologist. There is a suggestion that prolonged dosing with ketamine may provide a greater likelihood of therapeutic benefit. The current guidelines for the management of CRPS recommend an integrated interdisciplinary approach to the patient's care, which aims to reduce pain, restore function and improve quality of life. The ketamine infusion studies showed evidence of a clinically meaningful analgesic benefit (although transitory), something that is all too rare in the pharmacological management of CRPS.

Dr. Leano is a Board-Certified Anesthesiologist with more than 15 years of experience. He is accepting new patients already diagnosed with CRPS and patients that are currently having Ketamine infusions several miles away from Palm Beach County. Call Palm Beach Pain at (561) 248-1166 to make an appointment to continue your regular ketamine infusions near home or to evaluate if you can benefit from it.