AUTONOMIC dysfunction (AD)

A look at this picture will give you an idea of what this system does.



The brain and the spinal cord comprise the Central Nervous System (CNS) while the rest of our nerves make up the Peripheral Nervous System (PNS).

•The ANS is part of the PNS.

•The ANS generally controls many of the automatic (subconscious) bodily functions that we depend on every second.


For example, the ANS is responsible for the following situations:

  1. Bringing objects in to focus
  2. Salivating
  3. Sweating
  4. Regulating digestive fluids
  5. Controls Peristalsis (i.e., rhythmic contractions) which moves food and feces along in the body
  6. Alters the strength and rate of your heart’s contraction
  7. Changing the state of your lung’s airways to help efficiently oxygenate blood
  8. Controls blood flow to organs
  9. Urination
  10. Sexual Function
  11. Regulates metabolism
  12. Potentiating neuromuscular and cognitive processes



Reference for picture –


The ANS consists of 2 divisions:

The Sympathetic Nervous System (SNS) and the Parasympathetic Nervous System (PSNS).

• The SNS is also referred to as the “fight-or-flight” system as it directs the ANS to stimulate the body in a way that would be advantageous in the face of some sort of active endeavour from standing up suddenly to scurrying away from a threat.

• The PSNS is also referred to as the “rest-and-digest” system as it directs the ANS to stimulate the body in a way that would be advantageous in the face of some sort of passive endeavour like digesting or relaxation.

These two systems are complementary, like the yin and the yang.

Dysfunction in the way the ANS operates is common in those with concussions. As the ANS does “scut” work, albeit vital, most of us never consciously give it the credit it deserves.


Post-concussion, many of the symptoms can be caused by AD: dizziness, fatigue, blurry vision, sensitivity to light, lack of exercise tolerance, cognitive impairment, etc. These can in turn spiral into other post-concussion features like sleep disturbances, headache and low/irritable/anxious mood and many of their functional consequences on patients’ daily lives.


We provide 2 interesting examples:

  1. We recently treated a middle-aged gentleman who had been gaining a lot of weight despite not changing his diet or his exercise regimen. This was part of the problem as by sticking with his (aggressive) pre-concussion workout routine, he was not complying with the treatment of Autonomic Dysfunction (see more below). Suffice it to say, his weight started to improve when he exercised (strategically) less!


  1. Another middle-aged gentleman had well-controlled blood pressure with medication before his concussion. However, after his concussion, his blood pressure went quite high on a consistent basis, i.e., 190/100, etc. There was no other reason (other than AD) that could be clinically found to explain the sudden shift. He was reminded of standard lifestyle and diet management strategies for hypertension and had his medications adjusted. We then embarked on biofeedback training.

Practically, AD is usually diagnosed clinically. Concussion remains a significant cause of AD so a high index of suspicion is called for in all concussion patients. Intimate knowledge of the way it presents, its treatment and appreciation of features it shares with other diagnoses is required.

1. History

These patients will usually complain of one or many of the symptoms that could be caused by AD (see above). Some of these symptoms may not be typical symptoms of concussion – abdominal cramps, clamminess, feeling either warm or cold, etc.


2. Physical exam

Changes in blood pressure and heart rate (compared to pre-injury levels or even post-injury postural differences, i.e., sitting vs. standing); changes in measures of the eyes ability to accommodate for near targets; etc.


3. Functional exams

Bruce Treadmill Protocol can identify those with AD that present with exercise intolerance.

•Functional tests of the visual, neck and vestibular systems are often carried out on concussion patients. If symptoms persist despite the patient performing well on these specific challenges, it is a clue that AD is claiming part of the clinical picture.


4. Investigations

a. Specific investigations targeting the complaint (i.e., the effect) are often employed:

•Palpitations – Holter monitor

•Blood pressure changes – Ambulatory Blood Pressure Monitoring

•Urinary difficulty – laboratory investigations, cystoscopy, urodynamic studies, post-void residual ultrasound

•Abdominal issues – laboratory investigations, Imaging, Endoscopy

•Weight gain – laboratory investigations including a hormonal panel

•Sleep Disturbances – Sleep Diary


b. Biofeedback equipment can detect abnormalities of many of the systems directly impacted by changes in the ANS:

•Skin conductance – measure of the sweat gland responsiveness to stress and relaxation protocols

•Skin temperature – caused by your blood vessels ability to dilate (warm up) and constrict (cool down) to stress and relaxation protocols

•Blood pressure monitoring in response to postural changes, stress/relaxation protocols and breathing maneuvers.

Heart rate variability (HRV) is a big topic and one that receives a lot of attention recently with respect to AD and specifically concussion patients.


c. Traditional methods of looking for Autonomic dysfunction have variable success rates in different clinical contexts and are often impractical. These include methods like tilt-table testing and quantitative sudomotor axon reflex test (QSART).

We will focus our discussion to the treatment AD’s consequences in the context of concussion patients. A coordinated approach involving the treatment strategies below in a multi-disciplinary environment is effective.


1. Functional challenges: School/Work accommodations

2. Low Energy: Fatigue Management Protocols

3. Mood changes: Relaxation techniques, CBT, mindfulness, therapeutic activities, reintegrating the patient in normal activities of life

4. Sleep: Cognitive Behavioural Therapy for Insomnia

5. Blurry vision/Light sensitivity: prescription glasses/tint + Vision therapy

6. Reduced exercise tolerance: cardiovascular exercise, return-to-athletics protocols

7. Dizziness: Cardiovascular exercise protocol +/- Vestibular therapy


A comprehensive explanation of how each one of these treatments contribute to the treatment of AD; and how coordinated treatment on many fronts potentiates the response has its explanation in neurophysiology and is beyond the scope of this post. Suffice it to say, there are many treatment options for concussion patients afflicted with AD.


This brings us another treatment option that is very specialized, for which there is a lot of evidence, and which has been similarly well received by the medical and alternative medical community…Biofeedback training.


The patient’s case from the second example above is a good example of the utility of biofeedback training. For example, HRV training has evidence to show that increasing HRV is related to improvements in asthma, coronary artery disease, chronic obstructive pulmonary disease, fibromyalgia, heart failure, hypertension, irritable bowel syndrome, major depressive disorder, performance anxiety, PTSD. A glance at the image of all the organs affected by the ANS and one will notice that the pervasive nature of the ANS tallies with the versatile effect of biofeedback therapy.


We will soon post more education about biofeedback modalities and training.

Last update: August 2018