Following a concussion patients can develop symptoms of dysautonomia, such as exercise intolerance, an erratic heart rate, anxiety, sleep disorders, temperature dysregulation, fevers, nausea, gut dysfunction and pain syndromes. Some symptoms appear immediately, while others have a gradual onset.
Patients with dysautonomia often have variability in their symptoms relative to stress levels, sleep, diet, the external environment, and many other factors. In order to understand how your treatments are impacting a patient with dysautonomia, it is important to have objective findings, rather than solely relying on a patient's subjective day-to-day experience.
Conducting pre- and post-treatment neurological exams can provide exactly this kind of information. Here, I will examine the neurological mechanisms involved in such a disorder and outline bedside examination techniques that you can utilize before, during, and after treatments.
What Does a Concussion Do to the Brain?
Concussions involve rotational forces on the brain that cause damage to axons. Axons are the long body of the nerve that, during concussion, undergo shearing forces similar in concept to a wet towel being rung dry. This axonal damage can lead to neuronal death, or, if the nerve survives, can lead to a functional pathology — a dysfunction in nerve conduction and interruption of proper neurotransmitter release.
White matter and grey matter have different densities, and therefore, different velocities during rotational and translational movement of the brain within the skull. For this reason, axonal damage often occurs where grey and white matter meet, such as in the brainstem — the hub of autonomic nervous system activity. This is one of the mechanisms by which axonal shearing can lead to the onset of dysautonomia following concussion.
Understanding the ANS
The autonomic nervous system (ANS) is a complex network of regions in the brain including the mesencephalon, pons, medulla, amygdala, hypothalamus, and the insular and medial prefrontal regions of the cerebral cortex. The ANS controls circulation of blood to the brain, systemic blood pressure, heart rate and rhythm, temperature regulation, sleep patterns, and proper function of the gut.
In dysautonomia, these autonomic functions are not properly regulated, and there is a loss of balance between the sympathetic and parasympathic systems, leading to a wide range of symptoms including tachycardia, arrhythmia, poor temperature regulation, digestive dysfunction, blood pressure fluctuations, and cerebral blood flow dysregulation.
Many manifestations of dysautonomia are a product of too much sympathetic nervous system activity; elevated heart rate, increased perspiration, decreased intestinal motility, and pupil dilation are some examples. Immune system depression can also occur as a result of excess sympathetic activity.
Dysautonomia has been correlated with both irritable bowel syndrome, depression and anxiety disorders.1 The causal link between the brain injury and subsequent sequelae of autonomic dysregulation may easily be missed by both patient and practitioner if a thorough intake including a timeline of head injuries and onset of symptoms is not obtained.
For example, irritable bowel syndrome, or the onset of gluten and other food intolerances may actually be a consequence of dysautonomia that develops months to years following a concussion. When this is the case, therapies aimed at improving gut health alone, that do not take into account the ANS aspect often fall short of providing a satisfactory resolution of symptoms.
In dysautonomia there can exist an imbalance within the ANS and sympathetic activity between the right and left sides of the body. How can this be? The brainstem is comprised of three areas, the mesencephalon (midbrain), the pons, and the medulla.
Your Treatment Strategy
The pons and the medulla comprise the lower brainstem. Within the pons and medulla is a system called the ponto-medullary reticular formation (PMRF). This important network of neurons functions to inhibit sympathetic nervous system activity at the spinal cord level. It is clinically possible for there to be a decreased output of the PMRF on one side of the brainstem relative to the other that can manifest as an increase in sympathetic nervous system activity on one side of the body.
This becomes important to know in regards to acupuncture treatment strategy, and may determine whether a practitioner does bilateral needling or unilateral needling. Assessing ANS function and sympathetic activity on the left and right sides of the body will be the focus of the second article in this series. It is not enough, however, to simply assess ANS function alone. Other areas of the brain such as the frontal lobes and cerebellum are essential for providing activation of the brainstem. In seeking an understanding of why the brainstem and ANS may not be functioning ideally, a practitioner needs to understand if the neurological deficit also involves the cortex or cerebellum.
The right frontal cortex and the right cerebellum both provide activation to the right brainstem, and the left frontal lobe and left cerebellum provide activation to the left brainstem. Therefore, if a patient had a deficit in function of the right frontal lobe as a result of a brain injury, for example, that right frontal lobe injury can have a downstream consequence of decreased right-sided brainstem activation leading to a decreased output of the right PMRF.
Let's take this example one step further. If the right PMRF fails to inhibit the sympathetic nervous system at the spinal cord level, tachycardia can result. The sinoatrial node sits on the right side of the heart and controls heart rate. It receives sympathetic nervous system input via the right intermediolateral cell column (a tract within the spinal cord). In failing to inhibit the sympathetic output to the right intermediolateral cell column, the sinoatrial node is excessively stimulated and the heart rate becomes chronically elevated, or abnormally elevated with basic movements such as standing up and walking.
Examining the Brain
An understanding of the relationship between the frontal lobes, cerebellum, and brainstem necessitate the performance of a neurological exam that provides feedback on the integrity of each of these systems. Through such an exam, we can start to understand whether an imbalance does exist between the left and right sympathetic systems, and if so, whether a failure to inhibit sympathetic output is coming from the brainstem itself, or if the upstream cause is coming from the ipsilateral frontal lobe or cerebellum.
These findings can inform acupuncture treatment strategy. If there is a decrease in right brain function, scalp acupuncture on the right, and distal points on the left would be appropriate. If the decreased function is in the right brainstem, auricular points on the right would serve to activate the right vagus nerve which has its nuclei in the right brainstem. Collecting objective information on the integrity of the central nervous system is vital in monitoring the progress of a patient with a concussion and subsequent dysautonomia.
Reference
- Esterov D, et al. "Autonomic Dysfunction after Mild Traumatic Brain Injury." Brain Sci, 2017; 7(8).
