The myodural bridge and dural tension. A missing diagnosis of neurologic-like symptoms?

Ross Hauser, MD.

We are going to start this article with an examination of research surrounding an understanding of how the muscles in the back of your neck and the nerve pathways they use to move your head, may be causing a tugging on your spinal cord. This tugging can occur at the myodural bridge, a thick, dense collection of connective tissue, that connects the muscles to the dura of the spinal cord. Before I explain this in anatomical terms, let me explain it in human terms.

Here is an example story: Someone will tell us that they have an almost impossible list of neurologic, cardiovascular, and psychiatric-like symptoms and conditions that they suffer from. It has been suspected over the last few years that many of their problems are arising from issues in the cervical spine. These issues include spinal cord compression, nerve compression, and arterial compression, etc. A glaring feature of their cervical spine problems may be a wandering C2 which may be implicated as leading to the pain at the base of their skull, headaches, and dizziness.

Typically, doctors will look for a compression of the spinal cord being directly caused by the pressure of the C2. However, in some cases, a wandering C2 can expand these symptoms further. The wandering C2 can then start a cascade of instability problems leading to muscle spasms, headaches and the possibility of neurologic-like problems of swallowing difficulty, trouble speaking or with speech, facial numbness, tongue problems, and vision problems among others not by direct compression, but by pulling on the cervical muscles which in turn pull on the spinal dura which in turn pull on the spinal cord.

Most of the medical literature surrounding the examination of the myodural bridge and the tension it can cause by tugging on the spinal cord centers around the symptomology headaches. However this relativity unknown problem can in fact lead to big problems and a many year search for answers to a person’s worsening symptoms.

When the myodural bridge pulls on the dura, people may suffer from an expanded list of symptoms.

A brief introduction to dura tension

As will be explained again throughout this article, the dura is a thick membrane that protects the brain and spinal cord. It is the container for the cerebrospinal fluid that flows from the brain into the spinal canal. The dura is present in the neck from the C1 to C3 cervical vertebrae. When these cervical vertebrae are unstable and wandering, they cause tension on the muscles, which are in fact trying to hold the vertebrae in place. This tension is translated to the dura via the myodural bridge. When this tension is translated, this is when the symptoms begin. For more information please see my companion article Upper cervical instability and compression of the brainstem.

The myodural bridge – a focus on a newly observed cause of neurologic-like symptoms

Where is this tension on the dura coming from? Is it from muscle atrophy or muscle spasms in the back of the neck? Let’s start with a paper published by the Research Division, Logan University in Missouri (1). The results of this paper was addressed to the chiropractic community. Why start with this paper? Because it offers a non-surgical outlook towards solving the problems described below. Here is the paper’s learning points and some explanatory notes. The paper is quoted in the italics.

The role of posterior cervical musculature in sensorimotor control (simply how nerves and muscles work together to help you move, maintain balance, sense of spatial awareness), cervicocephalic pain (upper neck pain associated with headache), and stabilization of the spinal cord has been recently described.”

To summarize, the muscles at the back of the neck work with the nervous system to help you maintain balance and coordination. Disruption in this muscle-nerve pathway can result in headaches, neck pain, and possibly symptoms related to spinal cord compression. That you are here reading this article is an indication that you or a loved one understand these problems all to well and that you are looking for more answers than you may have received up until this point including that of a surgical consultation.

The role of the myodural bridge in these problems

Anatomical soft tissue connections which cross the cervical epidural space link suboccipital muscle fascia and dura. These myodural bridges provide passive and active anchoring of the spinal cord. They may also be involved in a dural tension monitoring system to prevent dural infolding, and maintain patency of the spinal cord.”

To summarize, there is a soft tissue connection that links the suboccipital muscle fascia and dura (as I will explain below the dura is the protective covering of the spinal cord). To understand this one step further, when you move your neck, if there is excessive hypermobility from cervical spine instability, that muscle may pull on that dura and in turn tug at the spinal cord. While obvious, that abnormal pulling on the spinal cord is not a good thing, the depth of problems this can cause are significant and not so obvious.

Modulation of dural tension may be initiated via a sensory reflex to muscular contractile tissues. (Explanatory note: Your body senses this abnormal tugging and now needs to decide what, if anything, it can do about it. It sends messages to the muscles’ very specialized contractile tissue, that part of the muscle that makes the entire muscle contract. What is a muscle is contracture? A muscle that can be in spasms as spasms are painful contractions and tightening of your muscles.)”

Unanticipated movements such as hyperflexion extension injuries (stimulate deep suboccipital muscles and transmit tensile forces through the bridge to the cervical dura. Due to its larger cross sectional area, the rectus capitis posterior major myodural bridge may exert greater mechanical traction on the dura than the rectus capitis posterior minor.)

To summarize, the muscles are pulling on the dura.

What are we seeing in this image? The muscles of the neck and the upper cervical myodural bridge.

The myodural bridge helps anchor the spinal cord during head and neck motions. When upper cervical instability is present, tension in the suboccipital muscles is transferred to the upper spinal cord and brainstem via the myodural bridge. This can cause symptoms of sharp neck pain, headaches, autonomic storms, and a host of other symptoms. Autonomic storms have “distinctive characteristics include fever, tachycardia, hypertension, tachypnea, hyperhidrosis, and dystonic posturing.”(2)

The muscles of the neck and the upper cervical myodural bridge.

As the researchers noted above: “Head movements are complicated movements involving activities of many muscles.” In the image above we see the rectus capitis posterior major muscle and its connection from the C2 to the base of the skull at the occiput.  It is one of the muscles that helps you nod and move your head.

What are we seeing in this image? The rectus capitis posterior major muscle tugging on the myodural bridge

In ligamentous upper cervical instability, spinal cord tension occurs with tightening of the spinal dura (the outer layer covering of the spinal cord) via the myodural bridges as the rectus capitis posterior major muscle attempts to pull the axis backwards. This tugging on the upper cervical spinal cord can cause severe sharp pain, headaches, autonomic storms, and a host of other symptoms.

The rectus capitis posterior major muscle tugging on the myodural bridge

The controversy surrounding the myodural bridge and dural tension

The controversy surrounding the myodural bridge is firstly an understanding of exactly what it is. There have been many ideas presented. A paper in The spine journal (3) offers this understanding:

“Studies over the past 20 years have revealed that there are fibrous connective tissues between the suboccipital muscles, nuchal ligament (the ligament that helps among other things, hold your head up), and cervical spinal dura mater.”

Simply, there are connective tissues, not normal connective tissues but a specific conglomerate of connective tissue that connect the muscles to the dura. Now what does it do beside get tugged on?

“Researchers have inferred that the myodural bridge might have important functions. It was speculated that the function of myodural bridge might be related to proprioception transmission, (muscle activity, balance, stability and posture, and locomotion) keeping the subarachnoid space and the cerebellomedullary cistern unobstructed, and affecting the dynamic circulation of the cerebrospinal fluid.”

Explanatory note: “The subarachnoid space consists of the cerebrospinal fluid (CSF), major blood vessels, and cisterns. The cisterns are enlarged pockets of cerebrospinal fluid.”(4) I will be discussing this important aspect of unobstructed CSF flow below.

“In addition, clinicians have found that the pathologic change of the myodural bridge might cause cervicogenic or chronic tension-type headache. Previous gross anatomical and histologic studies only confirmed the existence of the myodural bridge but did not reveal the fiber properties of the myodural bridge. This is important to further mechanical and functional research on the myodural bridge.”

The purpose of this study was to examine the make up of the myodural bridge and why was it able to pull so hard on the dura matter and cause dural tension. What the researchers found out was the Myodural bridge is mainly formed by parallel running type I collagen fibers; thus, it can transmit the strong pull from the diverse suboccipital muscles or ligaments during head movement.” 

The price of strong tissue

Up until this moment I have described the myodural bridge as tough connective tissue that connects to the dura mater that surrounds and protects the spinal cord. But why is the myodural bridge so tough? As suggested by researchers writing in the journal SRA Surgical and radiologic anatomy (5) “In the process of head movement, tensile forces could be transferred possibly and effectively by means of the myodural bridge complex.” Its tough because it protects head movement. That toughness can be turned against the body when the cervical bones are wandering.

The wandering C2. The mystery and controversy of the pulling on the dura mater – is this where your symptoms of unknown origin are originating from?

We are laying the ground work for an understanding of some of the symptoms you may be experiencing. Here, we discuss what happens when upper cervical instability causes muscle tension and spasm with a resulting pull on the dura matter. So now let’s further explore the dura matter.

As I mentioned above, the spinal dura or dura matter is the outer layer covering of the spinal cord. It is thick and dense so it can serve its function as spinal cord protector. As noted in the research paper the myodural bridges (tissue) fibers have different connective tissue types mixed in as does the dura matter. The mixture helps strengthen these structures. The dura matter also encloses the arachnoid mater, another layer of the meninges (coverings that protect the spinal cord)  which keeps cerebrospinal fluid from leaking out.

So up until this point we have an understanding that muscles in the cervical spine move the head. If the upper cervical spine is in a state of instability and the bones of the neck are wandering, the muscles that move the head begin to spasm. With this spasm is a pull on the dura or spinal matter. Symptoms develop. Now let’s explore further.

What are we seeing in this image? Dura tension build up, upper cervical instability and symptom development

To the right of the image is the progression of  upper cervical instability to symptomology

This leads to symptoms of:

Dura tension build up, upper cervical instability and symptom development

The nuchal ligament – what are we seeing in this image?

A cadaver study explored the upper cervical spine and evaluated the myodural bridges along with position of spinal cord in response to passive motion of upper cervical spine. The main focus is that when stress is placed on the nuchal line (where the muscles attach), it tugs at the spinal cord by creating tension on the dura.

A cadaver study explored the upper cervical spine and evaluated the myodural bridges along with position of spinal cord in response to passive motion of upper cervical spine.

The spinal cord moves within the spinal canal during passive movement.

The image above comes from doctors at the Department of Rehabilitation Sciences, Florida Gulf Coast University, Fort Myers. It comes from their published research in the journal PeerJ an Open Access, peer-reviewed, scholarly journal.(6)

In this paper the researchers suggested that the “myodural bridges between posterior suboccipital muscles and the dura might be important explaining conditions associated with the upper cervical spine dysfunction such as cervicogenic headache. This cadaver study explored the upper cervical spine and evaluated the myodural bridges along with position of spinal cord in response to passive motion of upper cervical spine. . . The presence of tissue connections between ligament, bone and muscles in the suboccipital region was confirmed. The nuchal ligament was continuous with the menigiovertebral ligament and the dura. Passive upper cervical motion results in spinal cord motion within the canal and possible tensioning of nerve and ligamentous connections.”

Basically, when the health workers performing the cadaver applied pressure to create a passive movement, he/she was able to, stress the spinal cord.

If you can nod your head, you can move CSF. What if you cannot nod your head? Suboccipital muscles impacting heart rate, breathing and headaches.

A paper was published in the prestigious journal Scientific reports in July 2021 (7). It comes from doctors at Dalian Medical University. Here is what the paper outlined:

“Head movements are complicated movements involving activities of many muscles. Amongst these muscles, the rectus capitis posterior minor, rectus capitis posterior major, and obliquus capitis inferior are located deep and posterior (behind) to the axis (C1) and atlas (C2).

It was well known that (these muscles) were connected to the upper cervical spinal dura mater via the myodural bridges through the posterior atlanto-occipital and atlanto-axial interspaces. Furthermore, studies have shown that the suboccipital musculatures including rectus capitis posterior minor, rectus capitis posterior major, obliquus capitis inferior, and the nuchal ligament participated in forming the myodural bridges complex. The myodural bridges (tissue) fibers from different origins could associate with each other and synergistically exert a pulling effect on the dura mater.”

Stagnant cerebrospinal fluid – The myodural bridge may act as a pump for CSF circulation dynamics

In the research we are examining in this article the study authors are suggesting another factor, problems at the back of the neck and muscle spasms may impact the myodural bridge’s ability to act as a CSF pump.

Remember the research team suggested that head movements are complicated movements involving activities of many muscles deep and behind the axis (C1) and atlas (C2) and there can be a pulling effect on the dura mater. They also made a suggestion that maybe considered controversial if not intriguing and may go a long way to explain many symptoms patients with upper cervical instability suffer from.

In this study, the research team cited two earlier papers that suggested that the myodural bridge may act as a pump for CSF circulation dynamics, and another paper that demonstrated that “CSF diastolic (fluid returns to the brain) flow was significantly affected by the one-minute-head-rotation period, indirectly supporting the myodural bridge CSF circulation dynamics hypothesis.”

As a further investigation upon the function of head movements, the present study found that the CSF flow was significantly affected in the one-minute-head-nodding period . . .suggesting “that means nodding-head has a strong tendency to slow down the cerebrospinal fluid pulsation velocity toward the cranial cavity, although there was no obvious impact on the volume parameters of CSF flow.” In other words the myodural bridge was acting as a regulating pump to help maintain balance of fluids in and out of the brain.

What are we seeing in this image? You need to flush the brain to get rid of neuron poop. The brain functions as a toilet to get rid of its poop.

This may be a whimsical way to describe this serious problem, but over the last few years, this idea of a brain not being able to flush away wastes has helped our patients as a simple, to the point understanding of their challenges. This subject is discussed at length in my companion article Treating neurologic-like symptoms by addressing cervical spine instability and disrupted blood flow into the brain. Indeed if you can identify this problem and present a treatment option, you can help people rid themselves of many neurologic-like symptoms as outlined already here.

The neurons are big consumers of food / fuel to create energy. Simply anything that eats a lot usually poops a lot. The brain naturally flushes this poop out with Cerebrospinal fluid (CSF). If for whatever reason, the toilet tank does not fill, the toilet tank does not flush into the brain, the toilet clogs and causes overflow, the poop does not move out of the brain.

As stated in the captions of these images. Obstruction of the arteries and veins, both into and out of the brain, from cervical instability and wandering vertebrae compressing these vital structures,  will ultimately result in an accumulation of Cerebrospinal fluid (CSF) in various parts of the brain including the frontal lobe. The neuron’s own waste will ultimately suffocate and drown them. This is one explanation for severe brain fog and mental decline in people with upper and lower cervical instability.

“the myodural bridge contributes to symptomatology and prognosis in mild traumatic brain injury”

There seems to be a connection between injury to the muscle, whether caused by cervical spine instability which put the muscle into constant states of spasms, or mild traumatic neck injury. Let’s explore a study published in the AJNR. American journal of neuroradiology.(8)

In this paper researchers explored the suggestion that suboccipital muscles affect symptom severity, neurocognitive performance, and recovery time in patients with mild traumatic brain injury.

How did the study work?

The neurological connection is well known

Here the researchers made a connection between cause of headache and the myodural bridge. “The dura is innervated by the first three cervical nerves, which converge with the trigeminal nerve. (The convergence occurs at the trigeminocervical nucleus caudalis where descending nerves from the brain meet with ascending nerves from the brain stem). Resulting activation of the nociceptors (pain snesors) in the trigeminocervical nucleus by these cervical nerves produces a cervicogenic headache. It is therefore not surprising that the low cross-sectional area (a weak or atrophied) rectus capitis posterior minor was associated with greater symptom severity and headaches in (the study group).

In fact, cervicogenic headache from injury to the rectus capitis posterior minor –dural connection is a well-known phenomenon in headaches from suboccipital procedures, where injury to the myodural bridge results in abnormal adhesions between the rectus capitis posterior minor and the dura.

Symptoms, headache, strange vibration in the upper lip, deep pain at the base of the skull, or severe pain between the eyebrows. Sometimes all of them.

In this video Ross Hauser, MD. discusses C0-C1 instability and the problems it creates on C1 nerve root compression. The highlights and summary transcript are below.

Occipital neuralgia

Below is a summary and the learning points of my article Occipital neuralgia and Suboccipital headache – C2 neuralgia treatments without nerve block or surgery.

Patients who write to us often describe a condition of hopelessness from a diagnosis of Occipital neuralgia or C2 neuralgia. They tell us about unrelenting headaches, pain and even swelling in the back of the head and neck. They will tell us about large doses of medications they take, some later to be found inappropriate or ineffective. They will even describe the problem of not getting enough medications.

Treatments that did not or helped short-term:

Occipital neuralgia and migraines are different problems and while similar in symptoms are vastly different in treatment needs. Or are they?

In your research on headaches, you may have come upon many websites that suggest that:

Your doctor may think you have Occipital neuralgia because your migraine medications are not working

For many patients, it is common to go through a long medical history that is in reality a process of elimination. Often Occipital neuralgia will be diagnosed on a basis of a medication or treatment that is not working.

A brief explanation of cervical ligament injury and headaches

In this video, Ross Hauser, MD, explains the mechanisms of cervical ligament injury and headaches.

Transcript summary:

Summary and contact us. Can we help you? How do I know if I’m a good candidate?

We hope you found this article informative and it helped answer many of the questions you may have surrounding your neck pain. Just like you, we want to make sure you are a good fit for our clinic prior to accepting your case. While our mission is to help as many people with chronic pain as we can, sadly, we cannot accept all cases. We have a multi-step process so our team can really get to know you and your case to ensure that it sounds like you are a good fit for the unique testing and treatments that we offer here.

Please visit the Hauser Neck Center Patient Candidate Form

References

1 Enix DE, Scali F, Pontell ME. The cervical myodural bridge, a review of literature and clinical implications. The Journal of the Canadian Chiropractic Association. 2014 Jun;58(2):184. [Google Scholar]
2 Rabinstein AA, Benarroch EE. Treatment of paroxysmal sympathetic hyperactivity. Current Treatment Options in Neurology. 2008 Mar 1;10(2):151-7. [Google Scholar]
3 Zheng N, Chi YY, Yang XH, Wang NX, Li YL, Ge YY, Zhang LX, Liu TY, Yuan XY, Yu SB, Sui HJ. Orientation and property of fibers of the myodural bridge in humans. The Spine Journal. 2018 Jun 1;18(6):1081-7. [Google Scholar]
4 Shafique S, Rayi A. Anatomy, Head and Neck, Subarachnoid Space. StatPearls [Internet]. 2021 Feb 11. [Google Scholar]
5 Zheng N, Chung BS, Li YL, Liu TY, Zhang LX, Ge YY, Wang NX, Zhang ZH, Cai L, Chi YY, Zhang JF. The myodural bridge complex defined as a new functional structure. Surgical and Radiologic Anatomy. 2020 Feb;42(2):143-53. [Google Scholar]
6 Sillevis R, Hogg R. Anatomy and clinical relevance of sub occipital soft tissue connections with the dura mater in the upper cervical spine. PeerJ. 2020 Aug 10;8:e9716. [Google Scholar]
7 Xu Q, Yu SB, Zheng N, Yuan XY, Chi YY, Liu C, Wang XM, Lin XT, Sui HJ. Head movement, an important contributor to human cerebrospinal fluid circulation. Scientific reports. 2016 Aug 19;6(1):1-7. [Google Scholar]
8 Fakhran S, Qu C, Alhilali LM. Effect of the suboccipital musculature on symptom severity and recovery after mild traumatic brain injury. American Journal of Neuroradiology. 2016 Aug 1;37(8):1556-60. [Google Scholar]

This article was updated August 31, 2021

 

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