SIBO: Small intestinal bacterial overgrowth and the Vagus nerve. The problem of nerve compression.

Ross Hauser, MD

Many people with a diagnosis of SIBO or Small intestinal bacterial overgrowth are very familiar with possible causes and treatments as they, you, have heard about many causes of SIBO and they may have tried many treatments.

If you are reading this article it is likely that the treatments you have had have not been effective enough or at all. Over time and as treatments failed, you may have been told the possible cause of your intestinal problem (focused solely on gastrointestinal distress) may not be the actual cause.

There is also a strong chance that your diagnosis of SIBO is only one of many health challenges you are facing. At our center, we see many patients with a myriad of mysterious and simultaneous conditions and symptoms. Typically they also start treatment with us by explaining and showing us the shopping bag full of medications that they are taking for each symptom and the very thick printout of all the tests that they have performed over the years.

For people with SIBO or other “stomach distress,” this would include rotating, alternating, and combinations of antibiotic prescriptions for Neomycin, Levofloxacin, Ciprofloxacin, Metronidazole, and Rifaximin. Some “enlightened” doctors may suggest the use of probiotics. As you probably know firsthand, all these medications are designed to try to address the problems and symptoms of abdominal bloating, cramping, and digestive disorders by reducing the number of bacteria in the intestine. You may be currently on this rotation now or have been on this rotation for years as a kind of “hit and miss,” treatment. As you also probably know, this strong regimen of antibiotics is also usually arrived at when there is an added diagnosis of Irritable Bowel Syndrome and its accompanying problems of diarrhea, constipation, problems with gas, and problems passing stool.

This article will present one possible explanation for your unresponsive to treatment SIBO with a focus on cervical spine instability compromising or impeding vagus nerve (Cranial Nerve X) function. This is a connection between your small intestinal bacterial overgrowth, your SIBO, and other related digestive problems such as Irritable Bowel Syndrome, Leaky Gut Syndrome, and vagus nerve compression.

A brief overview of SIBO

In June 2023, doctors writing in the World Journal of Gastroenterology (1) gave an overview of how SIBO may develop, how the path of the disease may travel, what other diseases or conditions SIBO may be implicated in, and what possible paths of treatment can be followed.

In summary, the learning points are:

  • Proton pump inhibitor therapy is a significant risk factor for SIBO.
  • SIBO is significantly associated with the following digestive issues:
    • functional dyspepsia (frequent upset stomach with no known cause),
    • irritable bowel syndrome,
    • functional abdominal bloating,
    • functional constipation,
    • functional diarrhea,
    • short bowel syndrome (parts of the small intestine are damaged, non-functional, or missing and the ability to absorb nutrients from foods are diminished),
    • chronic intestinal pseudo-obstruction (foods and liquids are impaired or prevented from moving down the intestines because of  intestinal nerve or muscle problems,)
    • lactase deficiency (lactose intolerance, the body does not make enough of the lactase enzyme),
    • diverticular and celiac diseases,
    • ulcerative colitis,
    • Crohn’s disease,
    • gastroparesis.
  • SIBO is significantly associated with the following neurologic-type issues:
    • multiple sclerosis,
    • autism,
    • Parkinson’s disease.

This list is a partial list. These disorders listed above also have in common a connection to disorders of the vagus nerve which we will explore below.

Part 1: Traditional treatments of SIBO

  • When diet hasn’t helped your Small intestinal bacterial overgrowth.
  • Antibiotics.
    • Helicobacter pylori and SIBO.
    • Antibiotics for SIBO and irritable bowel syndrome.
  • Proton Pump Inhibitors.

Part 2: Understanding Vagus nerve problems or problems of vagal tone

  • Cervical spine instability – The many ways cervical instability can cause small intestinal bacteria overgrowth.
    • Gastroparesis.
    • Low production of stomach acid.
    • Pyloric Valve Dysfunction.
    • Small Intestine Dysmotility.
    • Ileocecal valve incompetence.
    • Sphincter of Oddi Dysfunction.
  • Possible symptoms related to small intestinal bacteria overgrowth.
  • A myriad of symptoms or “multisystem disorder,” is not something unique to the people who reach out to us.
  • Sphincters, Valves, and Bowel Transit. The answer may be in the Vagus Nerve.
  • Digestion & the Vagus Nerve: Sphincter function and related symptoms affected by neck instability.
  • Vagal dysfunction and small intestinal bacterial overgrowth: The medical hunt for a connection.
  • The vagus nerve and the small intestines, inflammation, overgrowing bacteria, stuck valves, and high acid. The road may lead to cervical spine instability and neck pain.
  • Does the SIBO cause small bowel transit time or does the small bowel transit time cause the SIBO?
  • SIBO is a problem of stuck valves and excess acid.
  • The Vagus nerve and digestion.
  • Gastrointestinal symptoms and vagus nerve compression.
  • So how do we treat a patient like this and how do we determine if these problems are from a vagus nerve compression in the neck?
  • Treating cervical ligaments with Prolotherapy  – published research from Caring Medical.

Part 1: Traditional treatments of SIBO

Before we look into cervical spine instability and the vagus nerve as a possible cause or influencer in your SIBO issues, let’s explore recent research on the treatment of SIBO

When diet hasn’t helped your Small intestinal bacterial overgrowth

Many people have tried many diet regimens and they share why they may not have the desired effects on their SIBO situation. A June 2022 paper in The American Journal of Gastroenterology (2) discussed the problems of diagnosis and dietary recommendations for SIBO. “. . . The diagnosis of small intestinal bacterial overgrowth is limited by a lack of sensitive and specific tests, with significant knowledge gaps in relation to therapeutic measures to manage and cure small intestinal bacterial overgrowth. Currently, antimicrobials (antibiotic, antifungal, anti-parasitics) are the established management option.” The authors conclude with a possible explanation of dietary suggestions: “There have been significant clinical advances in dietary interventions related to the small bowel, but this area is currently a novel (new and evolving)  and advancing field for both patients and clinicians.


Helicobacter pylori and SIBO

The targeted effectiveness of antibiotics is of course desirable because of the complexity of a patient’s problem. In December 2023 in the journal BMC Microbiology (3) researchers acknowledged a “link between Helicobacter pylori (HP) infection and small intestinal bacterial overgrowth (SIBO) with nonspecific digestive symptoms. Nonetheless, whether Helicobacter pylori (HP) infection is associated with SIBO in adults remains unclear.”

In this study, the researchers reviewed previously published data to suggest that it is still not clear but through their analysis, a suggestion can be made that Helicobacter pylori (HP)  infection is associated with a higher prevalence of SIBO in adults, especially younger adults. Further, “The detection of SIBO should be considered for patients with digestive symptoms and Helicobacter pylori (HP) infection. Furthermore, there is a need to determine whether eradicating Helicobacter pylori (HP) can reduce SIBO in patients with this condition.” The question left unanswered is does eradicating Helicobacter pylori (HP) can reduce SIBO.

Antibiotics for SIBO and irritable bowel syndrome 

A January 2024 study in the Journal of Neurogastroenterology and Motility (4) performed the first systematic review to evaluate the effectiveness of antibiotics in relieving symptoms in patients with SIBO, and the first study to evaluate whether irritable bowel syndrome patients with evidence of SIBO are more likely to improve with antibiotics than irritable bowel syndrome patients without evidence of SIBO. What they found was that antibiotics may be effective at relieving symptoms in SIBO and that IBS patients with SIBO appear more likely to respond to antibiotics than IBS patients without SIBO. The findings according to researchers, support a precision medicine approach where testing for SIBO in IBS patients may help identify those more likely to respond to antibiotics.

Proton Pump Inhibitors

Here we will start making a connection to the vagus nerve. The function of the vagus nerve is described below.

Proton Pump Inhibitors are medications that inhibit or shut down the production of acid from the proton pump. Some people who contact us have a history of or have been recommended for a vagotomy to help ease their symptoms. A vagotomy is a surgery that removes all or part of your vagus nerve. Vagotomy is focused on helping people with stomach ulcers. The idea is that by cutting the vagus nerve, (the vagus nerve controls stomach acid secretion) stomach acids and the problems of acid erosion in the digestive tract can be managed and ulcers can heal. This procedure is not commonly performed as doctors were more eager to provide alternatives to this surgery such as proton pump inhibitors.

A January 2024 paper in the journal Digestive Diseases and Sciences (5) examined the increased risk of SIBO in patients with chronic Proton Pump Inhibitors use. The focus was on a short duration of seven days Proton Pump Inhibitor – 40 mg of pantoprazole. The catch was this study was performed on healthy volunteers.

  • Results: Thirty-eight healthy subjects (71.1% women, average age 25 years) were analyzed. The incidence of SIBO after 7 days of PPI administration was 7.8%. The patients who developed SIBO had a greater prevalence of bloating and flatulence after 7 days of treatment.
  • The conclusion: “Although inappropriate use of PPIs should be discouraged, but since more than 90% of subjects who received PPIs for one week did not develop SIBO, the advantages of PPI administration seem to outweigh the disadvantages.”

Part 2: Understanding Vagus nerve problems or problems of vagal tone

If your symptoms were limited to gastrointestinal distress, you would be in the hands of capable gastroenterologists and you would be managed and likely greatly helped. But what if your problems were bigger? What if SIBO and irritable bowel and possibly Leaky Gut Syndrome and its contributions of chronic diarrhea, constipation, bloating, nutritional deficiencies and even malabsorption, headaches, brain fog, skin problems, and joint pain joined in? What if your story sounded like these people’s that we will discuss below?

We are going to present information that these problems are related to Vagus nerve problems or problems of vagal tone.

Before you say I have read about that, or I have tried meditation and other stress-relieving techniques to help improve my vagal tone, that is not what this article is all about. This article is about identifying cervical spine instability, pain in your neck, and vagus nerve compression. This article is about how compression upsets and impacts the ability of your digestive tract to function properly. This article will also present options on how to possibly fix that.

Cervical spine instability – The many ways cervical instability can cause small intestinal bacteria overgrowth.

  • Gastroparesis
    • One of the symptoms patients may discuss with us is the constant presence of nausea and/or gastroparesis, a problem with their stomach’s ability to empty itself of food. While many readers may not be familiar with the term gastroparesis, they are familiar with the symptoms, heartburn, vomiting, the sensation of being bloated, a constantly full stomach, and of course nausea. I cover this subject at length in my article: How neck pain and cervical spine instability cause nausea, gastroparesis, and other digestive problems.
  • Low production of stomach acid.
    • The symptoms of low stomach acid are many. Problems digesting meat, undigested food in stool, heartburn, gas, bloating.
  • Pyloric Valve Dysfunction
    • In my article Pyloric stenosis in the adult patient: A problem of Vagus nerve impingement? I write about people who have food “stuck in their stomachs.” One possible cause for this stuck food may be a problem with the pyloric valve or the “doorway” that separates the stomach contents from those of the small intestine. When the pyloric valve doesn’t work properly, food stays in the stomach, and symptoms such as bloating, nausea, vomiting, and reflux can occur.  Eventually, if food can not be absorbed, weight loss occurs. Sometimes it is life-threatening.
  • Small Intestine Dysmotility
    • People diagnosed with Dysmotility are told they have a problem with muscles or nerves of the digestive tract or the nerves that cause food to pass through the digestive tract at abnormally slow transit times.
  • Ileocecal valve incompetence
    • In the medical textbook STAT Pearls, (6) housed at the National Library of Medicine, Ileocecal valve incompetence is described this way: “Patients with an incompetent ileocecal valve will decompress their large bowel into the small bowel and eventually present with vomiting, but a patient with a competent ileocecal valve will have ongoing distension of the obstructed colon, and will eventually present with significant right iliac fossa pain and impending cecal perforation (a perforation of the colon).”
  • Sphincter of Oddi Dysfunction
    • The sphincter of Oddi is a digestive tract valve that helps move bile (the liver’s digestive fluid stored in the gall bladder) and fluids from your pancreas into your small intestine. When this process is not working right it is called sphincter of Oddi dysfunction.

Possible symptoms related to small intestinal bacteria overgrowth.

These are examples of emails we receive, that have been edited for clarity. When someone presents with all these symptoms it is more likely to suggest something is at the root cause and that each disorder did not spontaneously appear for no reason. We will explore the vagus nerve as the root cause and the pressure exerted on it by cervical spine instability.

I believe I am suffering from cervical instability

I believe I am suffering from cervical instability and while my doctors may agree I have neck issues, they are confused and not sure that my neck issues are the cause of all the issues I have. In my neck, I have cracking, stiffness, and severe neck pain. The pain is causing pressure in my head, eye pressure, and vision difficulties. Many times I nearly pass out or faint when I stand. I have migraines, migraines from dizziness, and cognitive decline.

I have dysautonomia, interstitial cystitis, and bladder problems. I have chronic fatigue syndrome / Myalgic encephalomyelitis. My digestive problems include SIBO, constipation, and bowel obstruction. I have a history of years of antibiotic use.

It started with a car accident and a whiplash

I have many symptoms as they relate to my neck. The biggest problem was the whiplash injury I suffered in a car accident. Over time this caused me to have a military neck and loss of the natural curvature of my cervical spine. Some of my providers are suggesting that this whiplash problem is the cause of my SIBO and digestive disorders. I have a very slow GI transit time, sometimes this could approach a week. They have made mention of the vagus nerve and digestive problems and how I may have nerve compression.

It started with a car accident and neck and jaw injury, now my stool does not move.

I was in a car accident almost 8 years ago and fractured my jaw. Since the accident, I have suffered from C1 – Atlantoaxial instability. I have pain, stiffness, and loss of range of motion in my neck. Sometimes my neck gets stuck. After the accident, I also started having digestive issues. I have SIBO and a diagnosis of colonic inertia. My colon does not work. I do not make good stools and when I do, my stool does not move. It is stuck.

It got worse after cervical spine surgery.

I started having significant neck pain. It spread into my arms and I was diagnosed with c3-c7 radiculopathy. While this neck pain was worsening I started to have severe gastrointestinal issues. This included new and sudden food intolerances. There was concern about SIBO and bowel transit. I did however start taking better care of my health and watching the foods I eat.

As my neck pain worsened and more symptoms developed, I decided to go ahead with my surgeon’s recommendation for disc replacement surgery. This surgery did not go well for me. Besides the continued problems with cervical radiculopathy, my digestive problems have grown. I have bloating, and my stomach “jumps,” like in a spasm. I have a diagnosis of dyspepsia which only means to me that I have a problem with indigestion and I can’t get better with “better,” drugs. I also have problems with bowel transit time, inconsistent stools, and stool transit in my colon. I am just looking to make sense of all this and finally find the right path.

A myriad of symptoms or “multisystem disorder,” is not something unique to the people who reach out to us.

A case report offered in the journal Integrative Medicine (7) in September 2023 describes a 42-year-old woman who initially was seen for chronic SIBO and associated gastrointestinal complaints. This patient case demonstrated the importance of “the overlap seen between conditions such as Mast Cell Activation Syndrome, gastric dysmotility often manifesting as small intestine bacterial overgrowth (SIBO), dysautonomia, joint hypermobility disorders such as hypermobile Ehlers Danlos Syndrome (h-EDS) or other hypermobility spectrum disorders (HSD), and autoimmunity.” The patient’s final outcomes include “immense improvement upon mast cell stabilization with ketotifen, and remission of SIBO with low-dose naltrexone (LDN).” The paper stresses “the importance of careful history taking and the role of clinical suspicion on patient outcomes.”

Sphincters, Valves, and Bowel Transit. The answer may be in the Vagus Nerve.

Above I discussed where many people have made a connection between the Vagus Nerve and the problems of digestive disorders including Small Intestinal Bacterial Overgrowth. However, this connection is made usually in the context of someone suffering from stress and anxiety, and its remedies are called for in meditation, stress management, anxiety prescriptions, and medications. This would also include cortisol and adrenaline control and overstimulation of the “fight-flight” response. See our article on Autonomic nervous system dysfunction. But what few discuss or examine is the possibility that cervical spine instability is causing compression on the vagus nerve and this compression is distorting messages from the brain to the digestive tract. In other words, stool traffic is backed up, bacteria are showing up in places it should not, and gas is trapped.

What are we seeing in this image?

Cluster headache treatment - cervical ligament instability and the trigeminal and vagus nerves

If you look at the illustration above you will see where the Vagus nerve is closely related to the C1 – C2 – C3 vertebrae. While doctors usually discuss the vagus nerve in the singular sense, there are two vagus nerves, one on each side of the neck, and in combination, they are referred to as the vagal nerves. This means that the degenerative damage in your neck can significantly impact the function of one or both vagus nerves. The one on the left side of your body and the one on the right side of your body.

Digestion & the Vagus Nerve: Sphincter function and related symptoms affected by neck instability

Ross Hauser, MD discusses digestion and the vagus nerve as it relates to the sphincter function. In the histories of patients who we see in our center, they often feel like they hit a wall with regard to finding a resolution of symptoms or their digestion conditions because the focus has been too narrow. When looking at many digestive symptoms through the aspect of vagus nerve health, many times solutions can be found because the vagus nerve innervates many vital digestive organs. Thus, in our center, we find that in patients who have digestive complaints as part of their constellation of symptoms that also point to vagus nerve impairment, the upper cervical area and cervical curve should be analyzed and examined to see if this could be the cause of the issues.

Vagal dysfunction and small intestinal bacterial overgrowth: The medical hunt for a connection.

Digestive inflammation

Jessica Robinson-Papp, MD is a practicing neurologist and clinical researcher at the Department of Neurology, Icahn School of Medicine at Mount Sinai, New York. She specializes in helping people with HIV. In June 2018 she and her colleagues published a paper (8) making a connection between Vagal dysfunction and small intestinal bacterial overgrowth. Here are the learning points:

  • The idea is that vagal dysfunction, which occurs commonly as part of HIV-associated autonomic neuropathy, (Causing such symptoms as dizziness, fainting, digestive disorders, sweating abnormalities, and pupil dysfunction in senses light and dark), could exacerbate inflammation through gastrointestinal dysmotility, small intestinal bacterial overgrowth (SIBO), and alterations in patterns of soluble immune mediators. The study found that participants with vagal dysfunction had delayed gastric emptying and a higher prevalence of SIBO.

So one connection is that vagal dysfunction could cause digestive problems which would create inflammation in the digestive tract would worsen the problem it was itself creating. Inflammation is a problem caused by the vagus nerve.

An indicator of nerve inflammation

In 2007, a study was published in the World Journal of Gastroenterology (9) by a research team that wanted “to offer an explanation of one possible cause for functional dyspepsia (indigestion) and irritable bowel syndrome caused by cervical spondylosis.” In this study, the research team used laboratory rats who had surgically induced cervical instability at the C4-C6 levels. As a result, the researchers noted that in both the spinal cord and the stomach, there were elevated inflammatory markers including c-Fos protein, an indicator of nerve inflammation.

Symbiotic intestinal microbiota that presents a risk factor for intestinal inflammation

An interesting study came out of Switzerland in 2018. (10) What makes this study interesting is that it was led by researchers at the University Hospital of Psychiatry, University of Bern. Specifically the Division of Molecular Psychiatry. Molecular Psychiatry seeks to uncover biological mechanisms underlying psychiatric disorders and their treatment. We see many patients with cervical spine instability who have been recommended to psychiatry. Here the research team presents the biological aspect, not the psychiatric aspect, of gastrointestinal disorders as related to the vagus nerve.

“The gastrointestinal tract is constantly confronted with food antigens, possible pathogens, and symbiotic intestinal microbiota that present a risk factor for intestinal inflammation.” It is highly innervated by vagal fibers (vagus nerve) that connect the central nervous system with the intestinal immune system, making (the) vagus (nerve) a major component of the neuroendocrine-immune axis. This axis is involved in coordinated neural, behavioral, and endocrine responses, important for the first-line defense against inflammation.”

Above we see that the vagus nerve is shown responsible for fighting digestive tract inflammation.

The vagus nerve and the small intestines, inflammation, overgrowing bacteria, stuck valves, and high acid. The road may lead to cervical spine instability and neck pain.

The small intestine’s primary function is to absorb the nutrients from the food we eat. To do this very few bacteria are necessary.  Small Intestinal Bacterial Overgrowth (SIBO) is when an enormous amount of bacteria start residing and growing in the small intestine.

The small intestine is able to do its all-important nutrient absorption job well because there are a series of sphincters and valves and neurological mechanisms that control motility to ensure that when the partially digested food gets to the small intestine it is ready to have the nutrients absorbed.  When a person with SIBO gets on a food allergy elimination diet and good probiotics but symptoms persist it is most likely the SIBO is actually from a structural cause.

Most of the digestive tract from the pharynx to parts of the large intestine is neurologically under the control of the vagus nerve.  When a person has cervical instability that inhibits normal vagus nerve flow, the coordinated integrated processes that are necessary for proper digestion of nutrients break down.

The small intestine has very few bacteria because the bacteria in the food are destroyed by stomach acid and bile both of which are necessary for the proper breakdown of the food we eat.  When there is vagopathy (degeneration or decreased vagus nerve flow) a person can experience gastroparesis and low stomach acid, both of which can cause the chyme (partly digested food that goes from the stomach through the pyloric valve into the duodenum) to prematurely get into the small intestine before the food is digested properly.  In other words, the chyme is not ready yet for the small intestine.  When there is fat in the chyme, the bile produced by the liver and stored in the gallbladder is then released through the relaxation of the sphincter of oddi.  Dysfunction of the sphincter of oddi occurs when its neurology is off by decreased vagus nerve flow to it.  Without the normal amount of stomach acid breaking down the food (chyme) and an inadequate amount of bile going into the small intestine, there is a setup for whatever bacteria is in the food (chyme) to multiply and grow.

It normally takes six to eight hours for food to go from a person’s stomach through the small intestine when gastrointestinal motility is normal.  Since the vagus nerves communicate with the enteric nervous system, when there is low vagus nerve flow because of cervical instability, as the vagus nerve nodose ganglions sit right in front of the atlas, stomach, and small intestine paresis can occur, conditions commonly known as gastroparesis, intestinal dysmotility, and intestinal pseudo-obstruction.   Again the longer bacteria sit in the small intestine the greater the chance they will multiply, flourish, and cause SIBO.

Does the SIBO cause small bowel transit time or does the small bowel transit time cause the SIBO?

Dr. Bani Chander Roland, at the time of this study, was a researcher affiliated with Johns Hopkins Medical School and Yale University School of Public Health. He and his colleagues published a paper in the Journal of Clinical Gastroenterology (11) where they made an interesting post observation.

Here is an interesting observation.

  • Patients with underlying SIBO have significant delays in small bowel transit time.
  • The association between prolonged small bowel transit time and positive lactulose breath testing (the test to determine the number of bacteria in the digestive tract) may be useful in helping patients by targeting therapeutic options for those who are not responding to standard therapy.
  • Interestingly, patients with positive lactulose breath testing did not necessarily have generalized gastrointestinal motility suggesting that small bowel transit specifically predisposes to the development of SIBO. The slow bowel transit time caused the SIBO.

So here we have an observation. A disruption in the normal flow and transit of foods caused the SIBO. Let’s go a step further and continue with research from Dr. Bani Chander Roland.

SIBO is a problem of stuck valves and excess acid.

In the American Journal of Digestive Diseases (12) Dr. Roland Chander Bani continued this research by making these observations:

Small intestinal bacterial overgrowth (SIBO) is an increasingly recognized clinical syndrome; however, its origin and causes are poorly understood. In this study, the researchers hypothesized that loss of gastric acid, delayed intestinal transit, and ileocecal valve dysfunction may cause the development of SIBO.

Explanatory note: The ileocecal valve is a sphincter muscle where the small intestine and large intestine meet. When the small intestines are done absorbing foods, they pass the remnant product of digested food materials off to the large intestines at the colon.

  • Thirty patients with suspected SIBO were tested for their ability to move food through the intestines, ileocecal junction pressure which is the ability of the ileocecal valve to open and close properly and at the right times), small bowel transit time, and regional gastrointestinal pH. (The measurement for the amounts and potency of gastric acids).
  • Conclusions: Patients with SIBO have significantly lower ileocecal junction pressure (the valve is not opening and closing when it should), prolonged small bowel transit time, and a higher gastrointestinal pH as compared to those without SIBO.

The Vagus nerve and digestion

In my article Cervical spine instability as a cause of your digestive disorders, I give a detailed overview of the problem. I will summarize that article here:

When a patient comes into our center for cervical spine instability issues and they describe digestive problems, the digestive difficulties are usually one of many symptoms, as I described above. One of the causes of this myriad of symptoms may be found in compression of the vagus nerve. Among the many functions of the vagus nerve is that it provides 75% of the total input for the parasympathetic nervous system, part of the Autonomic nervous system.

Explanatory note: The autonomic nervous system is divided into two: the sympathetic nervous system  and the parasympathetic nervous system

  • The sympathetic nervous system controls energy flow to the digestive system during times of flight/fight. It slows down digestion so the legs and arms can get the blood they need as a priority. The parasympathetic nervous system restarts the digestive system when the stress passes. A malfunctioning Autonomic nervous system can lead to many digestive problems and symptoms including the development of SIBO.

The vagus nerve is responsible for managing our intestinal activity as well as managing the sphincter muscles in the gastrointestinal tract.

Gastrointestinal symptoms and vagus nerve compression

In this video Ross Hauser, MD. discusses a myriad of gastrointestinal symptoms that may be caused by vagus nerve compression typically found in cervical spine instability.

Below is a summary transcript with explanatory notes:

  • We see many patients with clicking, grinding, and crunching in their necks. They have terrible migraine headaches, neck stiffness, dizziness, ringing in the ears, swallowing difficulties, and other disabling symptoms. But our overall assessment also includes our look into these people’s gastrointestinal symptoms.

(0:40) What are we looking for by way of gastrointestinal symptoms?

  • We are looking for symptoms of:
    • Bloating
    • Very sensitive stomach
    • Constipation
    • Diarrhea
    • Crohn’s disease
    • Ulcerative Colitis
    • Irritable Bowel Syndrome

Some of these people have a long history of gastrointestinal symptoms and cervical spine instability, yet the connection was never made for them. Yet a connection can be obvious.

In the illustration below, the many things the vagus nerve is responsible for are outlined. Highlighting digestive disorders, we see that the vagus nerve:

  • Controls throat muscles to assist in swallowing
  • Regulates insulin secretion and glucose balance (homeostasis) in the liver
  • Regulates and controls digestion. Provides your brain with the feeling of satiation or “I’m full.” Helps regulate gastric juices, gut motility (the ability to move food through the digestive tract), and the production and regulation of stomach acids.

In this illustration, the many things the vagus nerve is responsible for is outlined. Highlighting digestive disorders, we see that the vagus nerve: Controls throat muscles to assist in swallowing. Regulates insulin secretion and glucose balance (homeostasis) in the liver. Regulates and controls digestion. Provides your brain with the felling of satiation or "I'm full." Helps regulate gastric juices, gut motility (the ability to move food through the digestive tract), and production and regulation of stomach acids.

The vagus nerve, and its important role in digestion that we explained above, runs right in front of the C1 vertebra.

(0:55) The number of disrupted nerve cells and how they cause digestive impairment

  • The vagus nerve cell bodies, which form the connection to the peripheral nerve processes of the visceral sensory nerves of the vagus, and their important role in digestion that we explained above, run right in front of the C1 vertebra. There are about 100,000 neurons in the vagus nerve and those 100,000 neurons have to tell the 100 million neurons in the enteric nervous system (the digestive system) what to do. So you can imagine if somebody has C1-C2 instability and the vagus nerve input to the digestive tract is hampered, there’s going to be a lot of enteric neurons in the digestive tract not working correctly.

(1:30) Digestive disorders and stomach acids

  • When the vagus nerve is working correctly it tells the stomach to secrete stomach acid. But if you have a vagus nerve problem, stomach acid production may be impeded and you cannot break down your food properly.
  • This would cause gastroesophageal reflux because the undigested food sits in your stomach and causes bloating
  • The vagus nerve also stimulates the pancreas to make enzymes so think of the double whammy you can’t make stomach acid then your pancreas can’t make enzymes that digest the food. Then the food is not getting absorbed so of course, you could get cramping and diarrhea.
  • You may also suffer from fatigue and feel very tired because you’re not absorbing the nutrients from the food.

(2:25) Intestinal problems, constipation

  • The vagus nerve also tells the intestines to contract so then if the vagus nerve isn’t working right you could also get constipation. In some cervical spine patients, they are taking laxatives to have a bowel movement. For some people, terrible constipation that they are suffering from has an undiscovered connection to their upper cervical or cervical instability issues.

(3:00) The liver and the spleen, fat absorption, and floating stools.

  • Even secretions from the liver and the spleen which control inflammation in the body all depend on proper vagus nerve input so for people who have gallstones or their liver isn’t working right, what tells the liver to make bile? What tells the gallbladder to release the bile? It is the vagus nerve. So bile is necessary for fat absorption. If you have a vagus nerve issue from cervical instability you could have fat malabsorption. You would know you have fat malabsorption because your stools float. Stools are supposed to be the consistency of a banana they’re supposed to slowly sink.

(4:05) Inflammation and spleen dysfunction

  • The spleen controls information, if you have body-wide, chronic inflammation, maybe an autoimmune disease such as rheumatoid arthritis, lupus, or Sjogren’s syndrome (dry eyes, dry mouth), there may be a cervical spine instability connection and there may be a structural cause of the disease which is cervical instability.

(4:30) Leaky gut syndrome

  • Leaky gut syndrome can be the result of diminished or impeded vagus nerve signaling. The tight junctions of the digestive tract widen and then you get substances that get into the bloodstream that shouldn’t be there. If you have been treated for a long time with leaky gut syndrome and you have vast food sensitivities and you’re not getting better you may actually have a structural cause of that condition called upper cervical instability hampering vagus nerve flow and causing the condition.

So how do we treat a patient like this and how do we determine if these problems are from a vagus nerve compression in the neck?

We perform dynamic and upright imaging, including Digital Motion X-ray and cone beam CT scan to assess for the integrity of the cervical curve as you can see here when the curve is normal we have a normal backward curve or lordosis, your head is sitting on top of your shoulders. In this position, the vagus nerve is properly positioned. We also check what we’ve termed “Neck Vitals” which looks at the size of the vagus nerve in the neck and function by measuring Heart Rate Variability.

  • When there is cervical spine instability, and there is a change to the natural curve of the neck, the vagus nerve is stretched and this stretching creates an unnatural tension on the nerve and this tension disrupts normal nerve signaling.

We see patients who are losing weight to the point that they should not lose anymore. When we put them in a cervical collar following Prolotherapy injections and we see them four days later they are eating again because “their stomach is working again.”

  • A conduction block – when certain nerve impulses in the vagus nerve aren’t going through or not going through from the brain to the stomach or the stomach to the brain.

The vagus nerve isn’t supplying your stomach and your stomach’s not working and you’re severely constipated or your colon is not working and your doctor said he got all these food sensitivities that won’t go away while you might have it where vagus nerve because the impulses to the enteric nervous system aren’t there to get leaky gut that is  causing your autoimmune diseases

Treating cervical ligaments with Prolotherapy  – published research from Caring Medical

Prolotherapy is an injection technique that stimulates the repair of unstable, torn, or damaged ligaments. When the cervical ligaments are unstable, they allow for excessive movement of the vertebrae, which can stress tendons, atrophy muscles, pinch on nerves, such as the vagus nerve,  and cause other symptoms associated with cervical instability including problems of digestion among others.

In 2014, we published a comprehensive review of the problems related to weakened damaged cervical neck ligaments in The Open Orthopaedics Journal. (13) We are honored that this research has been used in at least 6 other medical research papers by different authors exploring our treatments and findings and cited, according to Google Scholar, in more than 40 articles.

In our clinical and research observations, we have documented that Prolotherapy can offer answers for sufferers of cervical instability, as it treats the problem at its source. Prolotherapy to the various structures of the neck eliminates the instability and the sympathetic symptoms without many of the short-term and long-term risks of cervical fusion. We concluded that in many cases of chronic neck pain, the cause may be underlying joint instability and capsular ligament laxity. Furthermore, we contend that the use of comprehensive Prolotherapy appears to be an effective treatment for chronic neck pain and cervical instability, especially when due to ligament laxity. The technique is safe and relatively non-invasive as well as efficacious in relieving chronic neck pain and its associated symptoms.

Get help and information from the Hauser Neck Center at Caring Medical.


1 Efremova I, Maslennikov R, Poluektova E, Vasilieva E, Zharikov Y, Suslov A, Letyagina Y, Kozlov E, Levshina A, Ivashkin V. Epidemiology of small intestinal bacterial overgrowth. World Journal of Gastroenterology. 2023 Jun 6;29(22):3400. [Google Scholar]
2 Rej A, Potter MD, Talley NJ, Shah A, Holtmann G, Sanders DS. Evidence-Based and Emerging Diet Recommendations for Small Bowel Disorders. The American Journal of Gastroenterology. 2022 Jun 4;117(6):958-64. [Google Scholar]
3 Liao L, Su BB, Xu SP. Helicobacter pylori infection and small intestinal bacterial overgrowth: a systematic review and meta-analysis. BMC microbiology. 2023 Dec 6;23(1):386. [Google Scholar]
4 Takakura W, Rezaie A, Chey WD, Wang J, Pimentel M. Symptomatic Response to Antibiotics in Patients With Small Intestinal Bacterial Overgrowth: A Systematic Review and Meta-analysis. Journal of Neurogastroenterology and Motility. 2024 Jan 1;30(1):7. [Google Scholar]
5 Durán-Rosas C, Priego-Parra BA, Morel-Cerda E, Mercado-Jauregui LA, Aquino-Ruiz CA, Triana-Romero A, Amieva-Balmori M, Velasco JA, Remes-Troche JM. Incidence of Small Intestinal Bacterial Overgrowth and Symptoms After 7 Days of Proton Pump Inhibitor Use: A Study on Healthy Volunteers. Digestive Diseases and Sciences. 2024 Jan;69(1):209-15. [Google Scholar]
6 Lieske B, Meseeha M. Large Bowel Obstruction. InStatPearls [Internet] 2021 Aug 11. StatPearls Publishing. [Google Scholar]
7 Quinn AM. Complex Presentations, Identification and Treatment of Mast Cell Activation Syndrome and Associated Conditions: A Case Report. Integrative Medicine. 2023 Aug 1;22(4). [Google Scholar]
8 Robinson-Papp J, Nmashie-Osei A, Pedowitz E, Benn EK, George MC, Sharma S, Murray J, Machac J, Heiba S, Mehandru S, Kim-Schulze S. Vagal dysfunction and small intestinal bacterial overgrowth: novel pathways to chronic inflammation in HIV. AIDS (London, England). 2018 Jun 1;32(9):1147. [Google Scholar]
9 Song XH, Xu XX, Ding LW, Cao L, Sadel A, Wen H. A preliminary study of neck-stomach syndrome. World Journal of Gastroenterology: WJG. 2007 May 14;13(18):2575. [Google Scholar]
10 Breit S, Kupferberg A, Rogler G, Hasler G. Vagus nerve as modulator of the brain-gut axis in psychiatric and inflammatory disorders. Frontiers in psychiatry. 2018 Mar 13;9:44. [Google Scholar]
11 Roland BC, Ciarleglio MM, Clarke JO, Semler JR, Tomakin E, Mullin GE, Pasricha PJ. Small intestinal transit time is delayed in small intestinal bacterial overgrowth. Journal of clinical gastroenterology. 2015 Aug 1;49(7):571-6. [Google Scholar]
12 Roland BC, Mullin GE, Passi M, Zheng X, Salem A, Yolken R, Pasricha PJ. A prospective evaluation of ileocecal valve dysfunction and intestinal motility derangements in small intestinal bacterial overgrowth. Digestive Diseases and Sciences. 2017 Dec 1;62(12):3525-35. [Google Scholar]
13 Steilen D, Hauser R, Woldin B, Sawyer S. Chronic neck pain: making the connection between capsular ligament laxity and cervical instability. The open orthopaedics journal. 2014;8:326. [Google Scholar]


This article was updated February 7. 2024

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