Concussions and the Sympathetic Nervous System

Concussions usually involve symptoms from six physical domains that are sequelae of functional brain disturbances, but is there one domain that is more primary? In a large variety of concussion clients, they often experience disruptions in multiple domains.

Concussion domains are usually clustered in the following physical groups:

  • Visual 
  • Neurocognitive 
  • Vestibular 
  • Autonomic 
  • Structural 
  • Neurological 

Meanwhile concussion symptoms are grouped into 4 subgroups including physical, cognitive, sleep and emotional.

A common outcome measure used to evaluate these symptoms is the Post-Concussion Symptom Scale as part of the SCAT 5, and this outcome measure includes 22 symptoms for total score 132.

Key to treating concussion injuries is determining the primary domain that is most responsible for the symptoms. Being able to isolate the main domain is key to a quicker and full recovery. But which one is it and where do you start?  For example, visual ocular motor (VOMS) testing is one of the group of tests that can help isolate between vision, cervical, and vestibular symptoms.

Literature shows that a common area involved in post concussion symptoms (ongoing symptoms lasting greater than 30 days) is the autonomic nervous system (ANS). Over the past year in our practice at Honsberger Physio+, we have found that addressing the autonomic nervous system first with many of our concussion clients has resulted in quicker improvements in their symptomology. Using a system of tests proposed by Dr. John Beck and others, we have been able to isolate whether the ANS is the primary cause of symptoms. For example, clients often note aggravation of their symptoms with VOMS testing such a saccades (rapid side to side or up-down movement of the eyes with the head fixed). When the ANS has been normalized or taken out of the equation, saccade testing was symptom free. The importance of normal saccades is being symptom free for looking, reading, driving, and many other daily functions.

The premise of this approach is that the ANS balance is not present. The ANS consists of 2 parts: the sympathetic nervous system (SNS) and the parasympathetic nervous system (PNS). Each of responsible for different functions in the body but must work together to keep the body in homeostasis.  The parasympathetic nervous system is the "rest and digest" system, whereas the sympathetic nervous system is the "fight or flight" nervous system. In the ideal situation, the human body desires to spend most of its time in the parasympathetic state, but it needs to be easily able to switch to the sympathetic nervous system when needed. 

At Honsberger Physio+ we have seen that many clients post-concussion are often stuck in a constant SNS state, often referred to as sympathetic dominance or sympathetic dystrophy. In this state the body can manifest the following symptoms:

  • Sensitivity to light
  • Sensitivity to sound
  • High blood pressure
  • Sleep issues
  • Shoulder or neck muscular tightness
  • Tiredness
  • Irritability
  • Headaches
  • Anxiety/ depression
  • Digestive upsets

These symptoms should look very familiar to concussion symptoms!

A study in March 2020 in the journal of Gait and Posture evaluated the effect of forward head posture on the ANS and cervical sensorimotor control. They found that those with forward head posture showed a decrease in eye movement control, greater errors in cervical joint testing, and decreased postural balance stability, as well as a difference in ANS function. They hypothesized that normal cervical alignment is essential for sensorimotor control affecting neck proprioception, vestibular system, and visual system, and is essential for maintaining normal function of the ANS. A normal cervical lordosis may improve PNS activation and decrease the overall sympathetic tone, decreasing the adverse neck tension acting on the brainstem and cranial nerves.

Two common examples we have seen resolve quickly are VOMS symptoms as described in the earlier example with the saccades. A second example involves cervical hypermobility and postural positioning. Cervical restrictions such as upper neck joint limitations, which are often linked to headaches, are normalized quickly when the SNS dominance is reduced. 

To get a full post concussion recovery all concussion domains need to be normalized, but focusing on the primary domain has a greater opportunity to return an individual to their pre-injury lifestyle in a faster manner. Clinical experience at Honsberger Physio+ has shown that addressing the autonomic nervous system first, especially the sympathetic nervous system seems to have a greater impact on overall concussion recovery.

Written by 

Efan Gonsalves, PT, AT (retired) Clinical Director- Markham
Corporate Professional Services Director



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Feddermann-Demont et al. Br J Sports Med. 2017 Jun;51(11):903-918. What domains of clinical function should be assessed after sport-related concussion? A systematic review.

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Moustafa IM1, Youssef A2, Ahbouch A3, Tamim M3, Harrison DE4. Gait Posture. 2020 Mar;77:29-35. Is forward head posture relevant to autonomic nervous system function and cervical sensorimotor control? Cross sectional study.

Pertab JL et al. NeuroRehabilitation. 2018; 42(4): 397–427. Concussion and the autonomic nervous system: An introduction to the field and the results of a systematic review.


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