The Landscape of Chronic Pain

The Landscape of Chronic Pain: Broader Perspectives – free full-text /PMC6572619/ – by Mark I. Johnson – May 2019

Here is a recent lengthy review of what’s known about chronic pain: the various aspects of various types of pain under various circumstances.

This article shows the folly of making any numerical one-dimensional measurement of chronic pain, which can arise from a variety of causes, vary greatly over time and location, and make such intrusive incursions into our inner lives.

This special issue on matters related to chronic pain aims to draw on research and scholarly discourse from an eclectic mix of areas and perspectives.  

The Role of GABA in Anxiety

This Month’s Expert: Andrew Goddard , M.D., on The Role of GABA in Anxiety | Psych Central Professional – An interview with Andrew Goddard , M.D.

TCR: Dr. Goddard, you’ve done a lot of neurobiological research in anxiety disorders. It’s a very complex area, but basically what goes on in patients’ brains when they have a panic attack?

Dr. Goddard: It is complex, and initially researchers focused on the actions of monoamines in both depression and anxiety. The “monoamine theory” of depression holds that depression is caused by a depletion of norepinephrine and serotonin.

TCR: Is anxiety thought to result from the same thing?  

Epigenetic regulation of chronic pain

Here are three recent scientific full-text PMC articles about how chronic pain induces epigenetic changes which in turn may then also affect the pain in a feedback loop.

Epigenetic regulation of chronic pain  – PMC4422180 – 2016 Apr

Abstract

Chronic pain arising from peripheral inflammation and tissue or nerve injury is a common clinical symptom.

Inflammation-, tissue injury-, and/or nerve injury-induced changes in gene expression in sensory neurons of the dorsal root ganglion (DRG), spinal cord dorsal horn, and pain-associated brain regions are thought to participate in chronic pain genesis; however, how these changes occur is still elusive.  

Neuroscience 2016: Thermosensors

Neuroscience 2016: Part 1 | Thermosensors | Pain Research Forum – David Julius delivers sweeping history of thermosensors in featured lecture at Society for Neuroscience annual meeting – by Stephani Sutherland on 31 Jan 2017

Summary of a featured lecture delivered by David Julius, University of California, San Francisco. The lecture discussed the use of natural compounds to understand the structure and function of the TRPV1 ion channel.

Spicy plants and venomous beasts are the sources of natural products that have been used for decades to study neurophysiology. Rather than look for pain-relieving substances, Julius said he wanted to “flip the coin and find compounds that would activate pain.”

From a long list of compounds, a few emerged that could selectively activate pain-sensing nerve fibers, including capsaicin, menthol—which is cooling but can be painful—and isothiocyanates, volatile substances found in onions and other plants.  

Theories About Cause of EDS Pain

Below are 2 PubMed articles insinuating that EDS pain is due to central sensitization or general extreme pain sensitivity.

I still insist that EDS pain is mechanical (due to lax tissues) and/or biochemical (because cell walls are also made from our defective connective tissue). However, we cannot know if the amount of pain we feel is in “normal” proportion to the nociceptive stimuli we experience.

The question is: do we have more pain than average or are we just more sensitive to average pain?

In the “good old days”, before I had to take pain medication around the clock, I seemed extremely pain sensitive. Even a wrinkle in the bedsheet would become painful if laid on it too long.  

Management of Chronic Visceral Pain

Recommendations for the Management of Chronic Visceral Pain – Cindy Lampner –  July 05, 2016

The subjective experience of visceral pain and the neurobiological mechanisms that underlie it are substantially different from those of somatic pain, yet pain management strategies do not traditionally differ in their approaches.

As a result, the treatment of visceral pain frequently results in suboptimal outcomes and adverse effects on the GI tract.

Frequently diffuse, poorly localized and associated with autonomic and emotional reactions and alterations in visceral function, visceral pain is common across a range of clinical populations. 

Damage from Uncontrolled Chronic Pain

Here is a list of posts (21, through Dec 2016) covering the damage caused by uncontrolled chronic pain, both physical and mental.

While the news is filled with stories of damages from opioid abuse, the damages of pain itself are never mentioned anywhere in the media.

This leaves the public completely ignorant of all the biological damages pain patients suffer if they are not provided effective pain relief quickly.

These are arguments for allowing pain patients access to opioids, showing how important it is to eradicate pain by any means possible as soon as possible.  

Scientists discover a new class of pain relievers

Scientists discover and test new class of pain relievers – 6/2/2016

A research team at Duke University has discovered a potential new class of small-molecule drugs that simultaneously block two sought-after targets in the treatment of pain.

These proof-of-concept experiments, published June 1 in Scientific Reports, could lead to the development of a new drug to treat conditions including

• skin irritation and itching,
• headaches,
• jaw pain, and
• abdominal pain stemming from the pancreas and colon.

I find it odd that this drug treats pain only of specific types and in specific locations. 

Adenosine both causes and relieves pain

The Two Faces of Adenosine | Pain Research Forum – by Matthew Soleiman on 26 Jul 2016

Over several decades, adenosine—a purine nucleoside involved in many physiological and pathophysiological processes—has gained a reputation as a molecule that relieves pain.

But there have also been scattered reports that adenosine can produce pain.

Now, new research led by Yang Xia, University of Texas Medical School at Houston, US, helps make sense of adenosine’s dual nature.

mice with a deficiency in adenosine deaminase (ADA), an enzyme needed for the breakdown of adenosine, had sustained levels of circulating adenosine, which promoted mechanical and thermal pain sensitivity 

The Dichotomy of Substance P

The Dichotomy of Substance P in Mediating Analgesia in the PNS and Nociception in the CNS – Aug 2016  By Florence Chaverneff, Ph.D.

This is a very technical article about a very odd, and thus interesting, phenomenon.

The excitatory neuromodulator Substance P (SP) in the tachykinin family of neuropeptides is produced in the CNS and PNS.

Co-release of SP and glutamate, as well as upregulation of SP’s neurokinin G Protein-coupled receptors (GPCRs) have been implicated in acute and chronic inflammation as well as nociception.