What causes dystonia, really?

One of the most frustrating things about suffering from dystonia and other related neurological conditions, is that many of us get misdiagnosed and mistreated for years; once we finally do get a correct diagnosis, we are told that there is no way of knowing why we developed the condition and no real way to get better. Nothing could be further from the truth.

What I am about to share applies to most people with dystonia and related painful spasms (e.g. those related to TMJ disorder). It does not apply to those who were pretty much born with a dystonic spasm, generally on a limb, those who have temporary dystonic symptoms because of a drug, and those who have secondary dystonia caused by other conditions (Parkinson's, multiple sclerosis, etc.). For all the rest of us, read carefully! This information is truly life-changing. It is based on existing research, insights by leaders in this domain, as well as my experience with my clients’ and my own recovery.

Dystonia is an emergent phenomenon: a number of causes produce it together, and individual causal factors are insufficient to explain it. Not all of these factors have to be present in each individual, although a majority usually are.

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The main causes of dystonia are:

1. A predisposition for neuroplasticity;

2. Dysfunctional anatomical or physical inputs;

3. Physical trauma and scars;

4. Psychological trauma;

5. Repetitive movements;

6. Heavy metal toxicity and certain viral infections.

Let’s go into each one of these in detail.

1. A predisposition for neuroplasticity

Neuroplasticity is the brain’s ability to adapt and shape itself based on given inputs. Those of us who are blessed with a plastic brain may have an easy time learning and adapting to new circumstances such as a new country. We may be gifted at languages, proficient in playing a musical instrument, and may easily switch from one career path to another.

Yet this predisposition for neuroplasticity also has a more challenging side: just as our brain adapts and changes according to ‘good’, functional inputs, it can also adapt to accommodate dysfunctional inputs. Dystonia is just that: a form of maladaptive neuroplasticity.

With most of the following causal factors, you’ll see how the dystonic brain adapts to a dysfunctional input. It does so in order to allow us to live with an injury, an anatomical imbalance, or to protect us from reliving a traumatic experience.

The good news is that just as the brain learns a maladaptive pattern, it can unlearn it and substitute it with a functional one (see ‘How to Recover’).

1. Dysfunctional anatomical or physical inputs

Cranium

Many people with painful spasms and important imbalances in the body, whether they have a dystonia diagnosis or not, often have remarkably asymmetrical craniums. One side might be smaller than the other, one eye might be higher than the other, and the maxilla (upper arch) might sit in a crooked position. The sphenoid bone, the wing-shaped structure that connects the facial bones with the rest of the cranium, is often misaligned, as if pushed back on one side.

Such asymmetries cause a number of issues. First among them is that when the cranium is asymmetrical, the upper cervical vertebrae have to stack under an asymmetrical structure. This creates patterns of compensation that extend all the way to the toes. The shoulders and pelvis tilt up in all three planes (like the airplane in the image below), in order to allow the vertebrae to remain stacked underneath an asymmetrical cranium.

Image Credit: Wikimedia Commons.

This is not a stable homeostatic position, as it requires a significant amount of effort for the neuromuscular and vestibular systems to maintain equilibrium and even muscle tone despite the imbalance. It increases the likelihood, among other things, of a subluxation of the upper cervical vertebrae C1 and C2, potentially constricting the brainstem and contributing to neurological symptoms.

Temporomandibular joint (TMJ) disorder, or TMD

The cranium, the upper cervical vertebrae and the jaw constitute a single complex: each part helps maintain the entire body’s equilibrium together with the others. When one of these elements is challenged, the others may suffer. For this reason, asymmetries in the cranium increase the likelihood of temporomandibular joint (TMJ) disorders.

The temporomandibular joint is an extremely complex and delicate joint. The ends of the jaw bone, or condyles, sit in the fossa, a dip in the corresponding part of the cranium. Through that area pass numerous crucial cranial nerves, which are fundamental parts of the nervous system and crucial in understanding and rehabilitating dystonia (subscribe to the newsletter at the bottom of the Hope for Dystonia homepage to be notified of a future blog post on cranial nerves).

Depending on how the condyles sit in the fossa, cranial nerves on either side of the head may receive more or less pressure and therefore be stimulated more or less. This simple dynamic can cause a myriad of neurological symptoms, including oromandibular, cervical and generalized dystonia.

The reason for this is that the cranial nerves are at the heart of how our brain perceives the world and our place in it: sight, smell, hearing and taste center around cranial nerves; the tenth cranial nerve, or vagus nerve, performs a huge range of tasks, from regulating autonomic functions like heart rate, digestion and breathing to helping us perceive safety around us, as we learn from polyvagal theory.

What happens, for example, when the right branch of the vagus nerve is more stimulated than the left one, because of the way the condyle sits in the fossa on that side? The answer is a cascade of supposedly ‘mysterious’ neurological symptoms: the soft palate is tighter on the right side, there might be difficulty speaking (dysphonia), digestion might be impaired, and a pervasive sense of instability and lack of safety may predominate.

As another example, when the eleventh cranial nerve is affected, its ability to symmetrically innervate the muscles of the neck is impaired, and visible cervical dystonia may develop.

Lastly, it is important to note that an imbalance in the temporomandibular joints can in and of itself cause a subluxation (misalignment) of C1 and C2, adding another source of stress to the brainstem.

The temporomandibular joints might be imbalanced because of asymmetrical dental wear, missing teeth, short-sighted orthodontic interventions and much more. Whatever the reason, the implications of TMJ disorder for the health of the nervous system are hard to overstate.

Other

The condyles are of course not the only potential source of pressure on nerves. Enlarged lymph nodes in the neck sometimes apply pressure on certain cranial nerves causing dysphonia and cervical dystonia. This is just one of many examples of physical pressure on, and consequent stimulation of the nerves. As we’ll see below, scars can put pressure on nerves as well.

1. Physical trauma and scars

Physical trauma is never purely physical, as we are not purely physical beings: there is always a component of fear, grief or stored trauma. Both physical and emotional components of trauma exist in the same place: our nervous system.

Physical trauma can take many forms: injury from an accident, surgery, dental interventions, assault, and more. The consequences of such wounding can be more or less evident. Some of these injuries may leave scars in the body: tissue that can pull muscles, press nerves, and send all kinds of confusing messages to the central nervous system.

When such impactful scarring is present, the brain can find itself forced to adapt and accommodate the new inputs. For instance, if a scar from a difficult childbirth is pulling the left leg inwards, a woman may find herself twisting as she walks, pulled by dystonic spasms. The rest of the body will compensate in order to allow this new way of moving and being in the body, resulting in potentially far-reaching and debilitating symptoms.

There can be less visible consequences of physical wounding as well, such as lingering infections, swollen lymph nodes, internal scarring, and more; all of these can potentially impact the nervous system and start a process of maladaptive neuroplasticity.