Functional Neurology Terms and Concepts

Written By: David Burns

cubeCommunication between providers and patients is very important and it is something that many of us struggle with. Discussions involving brain often become confusing, especially when it comes to out of the ordinary, theoretical clinical applications.

Therefore, the following is a list of some of the terms, concepts or metaphors that are used at Brain Centers NW. The intent is to help the readers of this site and patients of Brain Centers NW gain a better understanding of the applications being used, tests, and reports that are implemented in clinical practice.

These terms may or may not be unique to Brain Centers NW. I encourage comment, criticism or expansion of these terms or concepts, but please understand that this is directed to patients and clients and not the medical community.

Baseline Testing: The idea of baseline testing is to know what a person’s present level of function is. The information obtained can either be used to proactively intercede if a relative functional deficit is discovered, which can exist without symptoms, or can be used as a benchmark of function in the event of a head injury.

To illustrate the range of applications of the information obtained I will use a metaphor of a “mental push up”. Let’s say that in order to function within their given sport or academic level a person needs to be able to do 10 mental push ups, so as not to exhibit symptoms. Now let’s say they experience a concussion and drop to an “8” mental push up capacity. Understanding that we are symptomatic when a stress is greater than our ability to handle it, this person would exhibit symptoms when trying to perform to the level that requires 10 mental push ups.

When we rely on symptoms alone, we end up letting the player return to play once they are asymptomatic, which only means they can perform 10 mental push ups. But what if prior to injury they could perform 15 mental push ups? As a parent would you want them at the level of 10 mental push ups or back to their 15 mental push ups or perhaps still higher at 17 or 20 mental push ups?

The only way to know how many “mental push-ups” they can perform is to do baseline testing. There are various levels of baseline testing. The more “windows” examined the greater the understanding of your child’s level of function.

“Brain Muscle”: Obviously, brain is not muscle. This analogy is used to communicate the idea that like the body, the brain is made of various “muscles” and that these muscles, like the muscles of the body, work in concert with one another. Moreover, like the muscles of the body these “brain muscles” can be exercised, strengthened and consequently can function at higher levels.

The strength and endurance of “Brain Muscles” are tested by looking at how quickly they respond to a stimulus and how long it takes them to fail. For example, when looking at the pupils we can look at how fast they respond to light and how long they take to fail. We can also compare one side to the other, to understand their relative strength and endurance. This is what I am referring to when I say the “rate of summation and fatigue”.

Now, when we are looking at the pupils, what is noted may be related to the pupils themselves or maybe a “window” into the areas of brain that perform the function of dilation and constriction or still further a “window” into the areas that fire into the areas that perform this function. The key point to understand is that we are looking at how fast things respond and how quickly they fail and that the entire neural network and relevant relationships are considered with each test or “window”.

Windows: I will often say that I cannot open you and probe at your various areas of brain, therefore I must look through as many “windows” into your brain and nervous system as possible to have as clear a picture as possible.

There are countless “windows” that reveal what is going on inside and the degree of clarity of that window is dependent on the observer’s capacity to see it and understand it, in that moment and how it relates to all that is transpiring at that moment.

A window is a physical manifestation that reflects the relative “strength” of what is going on within the nervous system. A few examples of the countless hundreds of windows include: gait, strength, tone of muscle, reflexes, eye movements, balance, coordination, attention, emotion, thought processing, likes / dislikes, musicality, sensory processing, heart rate and rhythm, pupils, respiration, blood pressure, posture.

Continuum: This term is used when discussing the “continuum of health” or perhaps the “continuum of function”. It is to say that, health or function is not an “either or” state; it is not “have or have not” but rather a dynamic state within a range from a very poor disease and symptomatic state to no symptoms and beyond to a higher functioning level wherein higher levels of “stress” to the system could be handled due to the relative increased “strength” of the system. It is to say that, one’s function can be significantly greater than simply being at a state without symptoms. Some have argued that being “well” has nothing to do with symptoms.

Symptoms vs Function: When one is symptomatic, it only means that the level of structure or function is not capable of handling the degree of stress being applied. On the other hand, a lack of symptoms only implies that the structure or function in question is handling the given level of stress being applied. For example, if you sprained your ankle it would be sore with any weight bearing. Once the symptoms are gone, while standing for example, do we say that the ankle is returned to its previous normal healthy state? Of course not. It only means that it can handle that degree of stress (i.e. standing). So the ankle is rehabbed or strengthened, to handle the level of function required for that individual’s needs (e.g. running, cutting, jumping).

Symptoms only mean that your level of function is less than than the degree of stress being applied. This notion is true for physical structures as well as relationships. A stress challenges a system and will increase the strength of the system so long as it is not greater than the system’s ability to respond.

At Brain Centers NW this concept is applied to brain, wherein the level of function is challenged to increase it’s relative strength so that at times of greater stress it will not begin to fail and directly exhibit symptoms (e.g. confusion) or indirectly (e.g. manifestations within the body).

Significant Findings: Many of the tests or diagnostics employed are standard tests that you would see performed during most neurological exams. What is perceived as significant, however, is where things may differ. When you are examining somebody from a disease model you rightfully have a higher point or threshold before you label something as abnormal. A “normal” finding could be interpreted to mean “common” or not significant enough to suggest pathology.

On the other hand from a functional standpoint I am looking for differences, side to side, top to bottom and relative to people I’ve seen before. Additionally, the finding itself is appreciated within the context of a picture that is created by all the findings as a whole. That is to say, does a pattern exist that would suggest weakness within a given network of assemblies of neurons.

This primarily true when looking at “physiological lesions” or soft lesions rather than hard lesions. For example, if you were doing a finger to nose test and you missed your nose by half an inch with the left hand but not the right, this might not be significant from a pathological standpoint but it does say to me that the structures responsible for the function on the left side did not perform to the degree that the structures on the right side performed. Now if something simple could be done to increase the function of the structures on the left side, I would imagine most would prefer that reality or honing of that function.

Protection Through Function: All things being equal, if one knee is stronger than the other and they both sustained the same degree of trauma, we would assume that the stronger knee would have a better outcome to that physical stress.

We know that those with ADHD or Dyslexia have a worse prognosis in the event of a concussion than those without this diagnosis. We know, through imaging studies, that these diagnoses are associated with relative deficits of function of certain areas of brain or “brain muscles”.

If that is true, and neurons are neurons, it might also be true that any area of brain that is relatively weaker would have a worse prognosis in the event of a concussion. For example, if the areas of brain associated with visual tracking are “weak” and it is this area that is concussed than it may be true that the prognosis would be worse than if that weakness was not present.

Perhaps, when we pay attention only to symptoms post concussion rather than level of function we allow an individual to return to play with a lower level of function or “weakness” increasing the probability of a subsequent concussion. If we increased the level of function perhaps we increase the relative protection of the brain. Note the author is not making a known evidence based claim, rather it is a hypothesis.

What does your brain need?: A brain needs food, oxygen and exercise. The first two are transported via the arterial system. The food that we eat and our cardiovascular fitness influences our brain integrity and function. Exercise for a neuron is dependent on the other neurons that it is connected to. Neurons require constant stimulation to survive and they depend on one another to do so. When one area of brain begins to falter the areas that it is connected to will in turn begin to decrease in function. In medicine this concept is termed “diaschisis”.

Each neuronal assembly is a node within a network wherein the firing of one node increase the probability of firing the nodes that it connects to. Like a muscle when a neuron is “fired” upon, if it is of sufficient input, whether that is an excitatory or inhibitory stimulus, it will result in protein replication within the cell. This is similar in a sense to our body muscles.

It is this protein replication, and the negative charge of protein that helps stabilize the neuron. A neuron without stimulus and subsequent protein replication will become weak and “unhealthy”.

Therefore, at Brain Centers NW our goal is to “exercise” these various “brain muscles” to help maintain their health and integrity. Think of us like a “brain gym” and the doctors as personal trainers or coaches for the brain.

Brain exercises: One of the intents at Brain Centers NW is to come up with individualized exercise plans that challenge the “weaker” areas of brain or generally try to increase the relative function of various “brain muscles”. These exercises are “neuroscientifically based interventions”. That is, these exercises are based off of the information that the scientific community has gleaned from imaging studies (e.g. PET or SPECT scans), information from known disease states as it relates to the function and structure of areas of brain (e.g. Parkinson’s) and the known result of injuries to various aspects of brain and the consequences of that injury.

Because these are theory based therapies or exercises, we measure or examine the level of function and expect that level of function or strength to increase with the application or exercise. If there is not improvement in function than two possibilities include: the exercise is not addressing the correct muscle or not enough “weight” has been put on the bar. That is, the exercise was not enough of a challenge or stress for the system to respond and become “stronger”.

Ablative lesion vs Physiological lesion: An ablative lesion refers to disease states or injuries wherein the connections are cut or interrupted between pools of neurons, “the road is out” (e.g. multiple sclerosis, stroke, tumors). Sometimes ablative lesions are referred to as hard lesions and physiological lesions are referred to as “soft” lesions.

A physiological lesion on the other hand, is referred to when we are talking about the relative strength or function of an area of the nervous system. Unlike, an ablative lesion the road between dynamic neuronal assemblies or nodes of neurons are intact. These physiological lesions can be a consequence of a lack of appropriate food or exercise (i.e. substrate or activation). The lack of exercise or input can be a result of an ablative lesion. For example, if a person suffers an injury to the right frontal cortex, physiological changes in the left cerebellum can be noted (i.e. diaschisis) by virtue of their connection to one another. We expect physiological lesions to change or improve.

Hemisphericity: This term can be flip flopped depending on the source. Within Brain Centers NW’s world, a hemispherity refers to the relative weaker half of the brain. It is my understanding that other professions (e.g. psychology) that the opposite is true and that hemisphericity refers to the stronger hemisphere. It should be understood that while one might be said to have a “right hemisphericity” it does not mean that relative weaknesses are not found on the left side. It is a general term of function or pattern only.

Network vs Focal Function: It is often thought that brain functions exist in a given area and that this area is independent of the other areas. This is rarely if ever the case. Brain functions have areas that are key to that given function but that given region is dependent on all the areas that it is connected to. That is to say, input A may not bring area B to threshold as a consequence of deficits of input from area B and C, thereby the given function of A may not be realized or at least may be altered qualitatively or quantitatively (e.g. sight, sounds, taste, memory). Within this notion of brain operating in a network or web of nodes is the reality that midline structures relate to midline structures, intermediate relate to intermediate and lateral relate to lateral. Therefore if a lower level midline structure fires, comes to threshold, there is a possibility of the areas above and below it firing as well. From an evolutionary standpoint, midline structures are older structures and lateral structures are newer structures. Old connects to old and new connects to new.

Recommended Further Reading:
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