Pain

Phantom Limb Pain is an example of neuropathic pain. In the United States, the prevalence of limb loss was 1.6 million in 2005, which is projected to increase to 3.6 million by 2050. Approximately 185,000 upper- or lower-limb amputations are performed annually. According to recent studies, vascular pathology is the most common etiology, accounting for 82% of limb loss discharges followed by trauma, cancer, and congenital anomalies.

The loss of a body part can lead to painful and non-painful neurologic categories: phantom limb pain, residual limb pain, and phantom sensations. Phantom limb pain is a painful or unpleasant sensation in the area of the lost body part. It can vary from pain described as a sharp, shooting, or electrical to dull, squeezing, and cramping. Phantom limb pain typically occurs within the first 6 months after the loss of a limb, but its prevalence several years after surgery has been reported to be as high as 85% and can persist for years after surgical amputation.

Treatment for phantom limb pain is difficult and challenging. There is often suboptimal treatment with fewer than 10% receiving lasting relief. Many studies have shown low-dose ketamine infusion therapy to be effective in the treatment of phantom limb pain when other traditional therapies proved resistant. NMDA receptors are known to play a central role in the development of phantom limb pain. Ketamine, a potent NMDA receptor blocker, has been successively used in many neuropathic pain conditions, such as phantom limb pain.

Also includes Restless leg syndrome (RLS), estimated to affect between 10-15% of the general population, is a sensory-motor syndrome characterized by people having uncomfortable sensations in their legs (and sometimes arms or other parts of the body) and an irresistible urge to move their legs to relieve the sensations. The condition causes an uncomfortable, “itchy,” “pins and needles,” or “creepy crawly” feeling in the legs. The sensations are usually worse at rest, especially when lying or sitting.

The severity of RLS symptoms ranges from mild to intolerable. Symptoms can come and go and severity can also vary. The symptoms are generally worse in the evening and at night. For some people, symptoms may cause severe nightly sleep disruption that can significantly impair their quality of life. RLS prevalence is higher in women than in men and the symptoms of anxiety and depression have been consistently associated with RLS.

As a result of the sensory-motor component within the central and peripheral nervous systems with RLS, and associated symptoms with depression and anxiety, treatment with intravenous ketamine has shown tremendous symptom relief and success for patients.

CRPS, also known as Reflex Sympathetic Dystrophy, is a progressive disease of the Autonomic Nervous System, and more specifically, the Sympathetic Nervous System.

The McGill Pain Index ranks CRPS as the most painful form of chronic pain that exists today. Anyone can get CRPS. It is estimated there are approximately 200,000 people in the U.S affected by CRPS. Seventy-five percent of the patients are women. The majority of those affected develop the disease in their 30’s and 40’s but it can be diagnosed at any age.

The four main symptoms of CRPS include constant, chronic burning pain, inflammation, spasms, and insomnia/emotional disturbances. The pain is typically accompanied by swelling, skin changes, extreme sensitivity, and can often be debilitating. It usually affects one or more of the four limbs but can occur in any part of the body and in over 70% of the patients it spreads to additional areas. There are a great many additional symptoms that can also occur over the course of the disease.

Current evidence suggests that the symptoms of CRPS are generated by a sufficiently intense or prolonged painful stimulus that causes increased and prolonged glutamate release. The glutamate released, in turn, stimulates NMDA receptors and causes central sensitization. Prolonged infusions of Ketamine (4 hours) appears to maintain a level of Ketamine in the central nervous system long enough to reverse the effects of the sensitization process and associated pain.

According to the Migraine Research Foundation, 12% of the population suffer from migraine headaches. This debilitating condition affects men, women, and children, but disproportionately affects women with 85% of chronic migraine sufferers being female. In 2015, the medical cost of treating chronic migraine headaches was approximately $5.4 billion.

Migraine headaches will often be characterized by throbbing, recurrent, moderate to severe head pain. However, a whole constellation of symptoms can be generated by migraines, including nausea, vomiting, visual disturbances, dizziness, sensitivity to light, sound, touch, and smell, and tingling of extremities and the face. Onset can be swift, and duration can be 4 – 72 hours.

There are some hospital in-patient services and hospital emergency rooms that have employed Ketamine infusions for several years to treat intractable migraine headaches. Recently, Dr. Eric Schwenk, the Director of Orthopedic Anesthesia at Thomas Jefferson University Hospital in Philadelphia, PA, and colleagues completed a retrospective study to ascertain the effectiveness of Ketamine in this population.

All sixty-one patients studied received daily low dose Ketamine infusions for three to seven consecutive days. Almost 75 percent of the patients experienced an improvement in their migraine intensity. On a scale of 0 – 10, the average migraine headache pain rating at admission was 7.5, compared to 3.4 on discharge. The average infusion was 5.1 consecutive days. The infusion day with the lowest average pain rating was day 4.

This study’s focus was on short-term relief. The author is encouraged by the potential for Ketamine infusions to provide long-term relief.