Complex Regional Pain Syndrome most frequently occurs following and injury but can also occur from long standing pain problems leading to central sensitization. CRPS is one of the most difficult disorders to treat.  Prior to discussing Sphenopalatine Ganglion Blocks in the treatment of CRPS it is important to understand the basics.

Patients with CRPS often experience Hyperalgesia or increased sensitivity to nociceptive input can be severe with even minimal noxious stimulation leading to severe or paroxysmal pain responses and Allodynia, the perception of pain from non-nociceptive input such as light touch.

Complex Regional Pain Syndrome is the current designation for what was previously called reflex sympathetic dystrophy (RSD) and /or causalgia
Another designation was reflex neurovascular dystrophy (RND) which is an amplified musculoskeletal pain syndrome (AMPS).

CRPS frequently is associated with systemic autonomic dysregulation with major effects on the CNS or Central Nervous System and resultant symptoms including neurogenic edema.

The International Association for the Study of Pain describes two types of CRPS: Type I previously designated as reflex sympathetic dystrophy (RSD) and Type 2 previously designated as Causalgia.

Type one is also referred to as Sludeck’s Atrophy, Reflex Neurovascular Dystrophy or Algoneurodystrophy. Type 1 is by far the most common type of CRPS . Nerve lesions have not yet been confirmed in type 1 CRPS.

Type 2 by contrast routinely has easily seen nerve damage which may be why it is more difficult to control. While Type 1 is often considered Idiopathic disease Type 2 has a presumed cause of obvious frank nerve damage.

Treatment is challenging in cases of CRPS and is often unsatisfactory especially after the condition has become advanced. The enormous degree of enhanced sympathetic activity causing secondary vasoconstrictionmake some believe there is an unidentified neurotransmitter involved.

My personal theory is a combination of Neural Plasticity causing severe Central Sensitization with increased afferent nociceptive sensitivity leading to storms of neurotransmitter release inside the brain and possible wide spread chages in Gap Junctions in the CNS which could explain the spread of CRPS in affected individuals. The communication could spread directly cell to cell and not synaptically. The Glial cells could be a likely suspect of transmitting this gap junction spread as would the Schwann Cells responsible for Myelin Sheath coverage of neurons.

Secondarily, there is a descending storm of efferent activity again leading to storms of neurotransmitter release as well as kinins and histamine that also may open up increased Gap Juntion spread of the disorder periferrally. The Afferent – Efferent spread will create an I/O error or input output error to the brain.. Computer experts would dub this
Garbage in – Garbage out.

In computers the tech would shut down the computer and reboot.  In humans this is a more difficult problem.  Ketamine has been used to treat CRPS but probably is most effective if used to prevent or reverse early CRPS.  Ketamine is effective in reducing opiod  use post-surgery.  Opiod use stimultes the Glial cell to break down opiods therefore decreaing the amount used to control pain is key.  Ketamine used to treat intractable neuropathic pain and is useful in preventing spinal sensitization, the wind-up associated with chronic pain.  By reducing neuroplasticity it may prevent development of CRPS and other disorders associated with Central Sensitization.

While this may help with pain it will not be an effective “reboot” of the system.  (below source wikipedia) The effect of Ketamine causes dissociation between the limbic and thalamoneocortical systems with intact ocular, laryngeal, and pharyngeal reflexes.  Ketamine is an antagonist of the glutaminergic N-methyl-D-aspartate receptor (NMDA-R), both centrally and in the spinal cord, prevents neuronal Ca2+influx, interference with neuronal plasticity, learning and memory, analgesia at central and spinal cord level, as well as interruption of the central sensitization core to chronic pain syndromes.

Ketamine could be used early to prevent Central Sensization but it has weak evidence in the literature.

Pain Med 2015 Jan 13. doi: 10.1111/pme.12675.  A systematic Review of Ketamine for Complex Rgional Pain Syndrome was a Cockchrane review that” yielded 262 articles, 45 of which met the inclusion/exclusion criteria. Of those included, 6 were reviews, 5 were randomized placebo-controlled trials, 13 were observational studies, and 21 were case reports.”  The conclusions were “there is no high quality evidence available evaluating the efficacy of ketamine for CRPS and all manuscripts examined in this review were of moderate to low quality. Therefore, we conclude there is currently only weak evidence supporting the efficacy of ketamine for CRPS, yet there is clearly a rationale for definitive study.”

This does not mean Ketamine is not effective in individual cases, it just cannot yet be considred a first line treatment.   I believe the reason Ketamine is only weak in response is that Ketamine doses are insufficient to reboot the system in both dosage and time of infusion.

The use of a Curare type anaesthesia is association with Ketamine may be the Reboot Mechanism that is necessary for severe CRPS.    Theis will reversibly inhibit the nicotinic acetylcholine receptor at the physiologic junction.  Curare was shown to effectively treat tetanus and strichnine poisoning by interfering with nerve conduction from motor neuron to muscle at the physiologic junction (think Botox).  This would require total life support including respiration.  While the patient is in the anaesthesized state Insulin Potentiation Therapy using a shocking dose of insulin could simultaneously be used to Reboot the system.  Hyperbaric Oxygen Therapy is currently under investigation for CRPS therapy and conceivably could be used in conjunction with Insulin Potentiation.  Insulin potentiation can also be used to move medications across cell membranes and /or the blood brain barrier.  This could allow targeted medication use to limit adverse side effects of the medications.  I first learned about Insulin Potentiation Therapy from a friend Dr Steve G Ayre a Canadian physician who worked with moving AZT across the Blood Brain Barrier in earl aids research.  I learned fro Steve about Insulin Potentiation and then used the addition of very small amounts of insulin to lidocine while doing trigger point injections.  Steve was conviced that Oxygen Potentiation held enormous benefits in  the future.

Insulin Potentiation may  become a treatment of choice for administering drugs to treat acquired Gap Junction Disease.

Cochrane reviews would never find evidence for drastic treatment of this type but considering the decrease in quality of life (QOL) in CRPS patients.  A study “Risk factors for suicidal ideation among patients with complex regional pain syndrome.” by Lee DH, Noh EC, Kim YC, et al. in Psychiatry investigation. 2014 Jan;11(1):32-8. reported 74% of patients were considered at high risk for suicide. (abstract below).

The severe nature of CRPS and effects on QOL or Quality of Life demands seeking answers for our patients.  Sympathetic Blocks including stellate ganglion blocks have had some success but there is little wrtten on the utilization of Sphenopalatine Ganglion Blocks for treating CRPS.  ”

I recently had a patient in my office for routine dental work but due to her severe CRPS we had anaesthesia with Ketamine to facilitate what otherwise would have been incredibly painful experience.  After the necessary dental work was done a bilateral SPG block was performed thru the greater palatine foramen intra-orally.  The patients husband the pain relief from the Ketamine infusion lasted longer than when she goes in for just Ketamine infusion.  These changes could be due to dosage and time of infusion or to addition of Parasympathetic Ganglion Block of the Sphenopalatine Ganglion.

I first began utilizing SPG Blocks in the 1980’s when a  TMJ/ Headache/ Migraine patient brought in the book “Miracles on Park Avenue” about an ENT physician who treated all matters of pain with Sphenopalatine Ganglion Blocks.  The patient wanted me to    help them find a doctor who would perform the block.   There were no doctors in greater Chicagoland area but a friend and mentor Dr Jack Haden in Kansas City taught me a simple method of doing SPG blocks transnasally.  The effect was life changing for my patient and I have been an advocate ever since.  There are numerous protocols for administering SPG Blocks including intra-oral and extra-cranial injections and transnasal approaches such as MiRx protocol with TX360 or use of Sphenocath.  I prefer the original method I learned for Jack Haden and the book “Miracles on Park Ave: Treatment of Arthritis andd other Chronic Pain” by Albert Benjamin Gerber.  The bibliography ain that book was my library index of articles I read to understand the SPG block.

The advantage to the original approach is that it can easily and safely  be self administered by patients at home one or multiple times daily and is extremely effective in eliminating and/or preventing pain in many patients.  It is a tool I use in treating TMD (TMJ) patients, Migraine , Chronic Migraine, Autonomic Cephalgia, Tension headache and Chronic Daily Headache patients.

Correcting underlying physiology is easier when patients are comfortable.

“Risk factors for suicidal ideation among patients with complex regional pain syndrome.”  Lee DH, Noh EC, Kim YC, et al.    Psychiatry investigation. 2014 Jan;11(1):32-8.

***What follows is Reprinted from the National Institute of Neurological Disorders and Stroke*****

http://www.ninds.nih.gov/disorders/reflex_sympathetic_dystrophy/detail_reflex_sympathetic_dystrophy.htm

What is complex regional pain syndrome?

Complex regional pain syndrome (CRPS) is a chronic pain condition most often affecting one of the limbs (arms, legs, hands, or feet), usually after an injury or trauma to that limb.  CRPS is believed to be caused by damage to, or malfunction of, the peripheral and central nervous systems.  The central nervous system is composed of the brain and spinal cord, and the peripheral nervous system involves nerve signaling from the brain and spinal cord to the rest of the body.  CRPS is characterized by prolonged or excessive pain and mild or dramatic changes in skin color, temperature, and/or swelling in the affected area.

Anyone can get CRPS. It can strike at any age and affects both men and women, although it is much more common in women. The average age of affected individuals is about age 40. CRPS is rare in the elderly. Children do not get it before age 5 and only very rarely before age 10, but it is not uncommon in teenagers.

What are the symptoms of CRPS?

The key symptom is prolonged pain that may be constant and, in some people, extremely uncomfortable or severe. The pain may feel like a burning or “pins and needles” sensation, or as if someone is squeezing the affected limb. The pain may spread to include the entire arm or leg, even though the precipitating injury might have been only to a finger or toe. Pain can sometimes even travel to the opposite extremity. There is often increased sensitivity in the affected area, such that even light touch or contact is painful (called allodynia).

Doctors aren’t sure what causes some individuals to develop CRPS while others with similar trauma do not. In more than 90 percent of cases, the condition is triggered by a clear history of trauma or injury. The most common triggers are fractures, sprains/strains, soft tissue injury (such as burns, cuts, or bruises), limb immobilization (such as being in a cast), or surgical or medical procedures (such as needlestick). CRPS represents an abnormal response that magnifies the effects of the injury. In this respect it is like an allergy. Some people respond excessively to a trigger that causes no problem for other people.

Currently there is no single diagnostic test to confirm CRPS. Diagnosis is based on the affected individual’s medical history and signs and symptoms that match the definition. But because several other conditions can cause similar symptoms, careful examination is important. Since most people improve gradually over time, diagnosis may be more difficult later in the course of the disorder.

The outcome of CRPS varies from person to person. Almost all children and teenagers have good recovery. Occasionally individuals are left with unremitting pain and crippling, irreversible changes despite treatment. Anecdotal evidence suggests early treatment, particularly rehabilitation, is helpful in limiting the disorder, but this benefit has not yet been proven in clinical studies. More research is needed to understand the causes of CRPS, how it progresses, and the role of early treatment.

How is CRPS treated?

The following therapies are often used:

The National Institute of Neurological Disorders and Stroke (NINDS), part of the National Institutes of Health (NIH), is the primary Federal supporter of research on the brain and central nervous system. Other NIH institutes also support research on CRPS and other painful conditions.