Protocols and Degrees of Freedom

Protocols

Protocols are nice packages of processes that allow for a task to be completed or a problem to be addressed in a predictable organized fashion.  They allow for for the process to be easily communicated, taught and used by a new person.

Protocols and the special needs needs child

Behavioral  optometry  recognizes the effect and importance of vision on the rest of the body. The effect of the visual intervention on the rest of the body increases the number variables that will effect the outcome of a protocol. Just as we as therapists must recognize the role of vision in the interventions we apply, the behavioral optometrist must also recognize the interaction of their intervention on the rest of the body.

An example:

A child with cerebral palsy develops a toe walking gait as a pathological solution to ambulating with increased trunk and lower extremity tone.  The application of base down prism, a common solution for toe walking, would, in this instance, destabilize this patient’s  gait and balance, most likely making him unable to walk. The visual input would be attempting to make his body do something it is unable to do. Is the base down prism helpful when when used during physical therapy sessions after a child has had other interventions for muscle tone? Maybe. This is the point at which an interdisciplinary team with a collective understanding of the entire person becomes most useful.

The larger point of the example is that the entire system is affected by the visual intervention but without an understanding of the entire system, the success of the protocol decreases.

Degrees of freedom

The variables within any biological human system are are complex and innumerable. The biological factors that influence the behaviors and abilities of children with special needs are even more difficult to list. Vestibular, proprioceptive,  muscular tone, sensory interpretation, etc, all are acting upon every human at all times. As a child presents to a provider, the provider must understand these systems and take into account the affect a change to any one of the systems will have upon the others. This is the challenge of anyone working with special needs children.

But a child’s degrees of freedom reach beyond his biology. All children exist in a context that includes parents, siblings, socio-economic factors, and teachers that also have an effect upon their behavior and abilities. A failure to acknowledge and understand these factors will also make the outcomes of interventions difficult to predict. As therapists working with children, it is all of these things that make us continuously look for understanding of the entire context for each child allowing us to treat this child in the most efficient way.

Toolbox vs Protocols

A large part of a therapists education involves learning to assess the degrees of freedom of the systems that that fall under their disciplines scope. Occupational therapists learn about the developmental sequence, range of motion, coordination and strength assessment. We learn standardized assessment for sensory processing and function ability and many other things. Physical therapists look at posture and gait, muscle tone, and balance. Speech therapist learn about swallowing, articulation and language processing.

But speech therapists also recognize the importance of posture for breathing to produce sounds. OTs know that a child without sufficient hand strength cannot use a walker to help him walk. A physical therapist knows a too cold room will affect the behavior of their sensory sensitive patient.  We are taught to have a holistic view of our patient to be successful.

Most therapists will talk about their “toolbox” rather than a protocol. Even interventions presented as a protocol, will quickly be modified and changed to accommodate a child’s needs and make the intervention more successful.

The Message

As the scope of behavioral optometry evolves, know that an understanding of the interaction of all systems, including the patient’s individual context, will render protocols less and less useful. The provider intervening must be able to apply tools from their toolbox freely and confidently to adjust for constantly changing demands of a specific patient and the individual needs of their special patient.

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Sensory Modulated Postural Dysfunction

Posture and Vision

The magnocellular tract plays an important role in posture. It provides visual information that allows for spontaneous adjustment of posture and muscle tone as the environment changes. Integration of vestibular information with this visual information helps keep us stable when are moving.

Think of standing on a boat gently pitching to and fro on the water. As the boat rock, the muscles of ones legs, trunk, and neck all compensate and adjust to allow you to stay standing. Imagine how hard it would be to do this if one were blindfolded. It would be much more difficult if the brain was unable to get accurate data about the changes in horizon and the incoming waves.

Sensory Modulated Postural Dysfunction

SMPD is one of the subtypes of sensory dysfunction described by the Star Institute. Marked by postural weakness and decreased stamina (what we may have described previously as “low tone”), these children have difficult times sitting up tall and may demonstrate a head-forward, flexed posture with shoulder rolled forward and possible scapular winging. They may have weak hands and present to OT for difficulty with handwriting or visual motor integration. In optometry, they call this postural dysfunction or other terms.

Posture is Vision Is Posture

The link between posture and vision is very important. Decreased visual acuity or decreased magnocellular awareness can cause the brain to get poor information about the body’s position in space and not allow for appropriate muscular corrections as the environment changes and the child moves.  The vestibular system as well requires visual input to allow for correct adjust adjustment of posture. We might observe this as a clumsy child or a child with weak posture.

As therapists, it is important that we make sure our young patients have a full and complete eye exam as we begin to address postural weakness, visual motor integration and handwriting problems. An uncorrected visual system will make treatment very difficult. But an appropriate visual system becomes a powerful tool to help correct these problems.

Vision as a Postural Tool

It is possible to make use of the powerful magnocellular system to help with posture. The addition of prism or binasal occulsion during a typical treatment for postural problems and “low tone” can alter the perception of visual space. Base down prism will shift visual space upward, making the head go up. When the goes up, the trunk moves into more extension. The brain quickly makes adjustment to the body based on the altered visual space.

Can they see?

I continue to find children with a full team of professionals: PT, OT SLP, ABA, pediatricians, etc,  that have not had an eye exam. Know the ODs in your town that perform comprehensive binocular vision exams and make sure your kiddos can see !!

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Motion sickness and the eyes

Motion Sickness

As part of my vision rehab evaluation with patient I always ask about motion sensitivity (or car sickness). The answer can give cues to the functioning of the ambient (magnocellular)visual system.

What is motion sickness?

The semicircular canals within the ears (vestibular system) tell the body that it is motion. The magnocellular visual pathway also “confirms” this motion as movement is observed. But when the system is less aware of magnocellular output (such when one is reading or playing a game in the car) then the vestibular and the magnocellular system get different information. When this happens nausea and rest follow.

The magnocellular system

The magnocellular system is responsible for visual input that affects gait, posture and balance. It also helps us track during reading as it gives the brain the ability to see the line peripherally as the eyes focus on the words being read. There was some discussion that magnocellular problems were associated with dyslexia as well.

Treating the Magnocellular system

To improve magnocellular input, we do activities on a balance board while performing visual scanning tasks that emphasize keeping the head still and maintaining balance as targets are toughed. I will have patient do this while wearing glasses with binasal occlusion or base up or down prism depending on posture. This can also be helpful with idiopathic toe walking.

More recently, motion coherence tests have been developed which help to quantify magnocellular function. In these computer based tests, dot move randomly and the patient must decide which direction most of the dots are moving. Devices like the Neuro-tracker also work on magnocellular function.

Using the system as tool

The magnocellular system can be a powerful tool in improving posture and balance. The altered visual input quickly re-aligns posture without cueing and makes use of the brain natural ability.

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Balance and Vision

 

Two Visual Pathways

The focal, central or Parvocelluar visual system is called the “What” vision system. It is responsible for object identification. It allows us to focus on a specific object in the visual field. This information is interpreted in the occipital lobe.

The ambient/peripheral or Magnocellular visual system is the “Where” system responsible for spatial information, balance, coordination and peripheral awareness. This information is shared with the occipital lobe, in addition to links to the cerebellum and balance areas of the brain. Functional MRI shows this information actually reaching 99% of the cortex. Using ambient vision, we can automatically change our posture and gait to walk uphill or protect ourselves from falling over as someone bumps into us.

Functionally, these two systems allow use to look at the road ahead of us (focal vision) and be aware of the car to our left(ambient). It also allows us look at the TV but be aware of where the door in the room is. It allows us to be focused on a word in reading, but still make accurate saccades to the next word.

Notice what happens to the people attempting to walk through the tunnel.

Notice how the people in the tunnel are leaning to one side. The tunnel walls have confused their ambient vision system and affected the gait and balance.

A tool for rehabilitation…

Frequently this system can become faulty following a neurological event. In a condition called Post Trauma Vision Syndrome”, patients become over-centrally focused. This is seen clinically as decreased balance, decreased reading accuracy and poor spatial awareness a midline shift or toe/heel walking.  The patients also report becoming “over-stimulated” by visual information.   A visual field done a patient with this condition might look like this

peripheral loss

This is one eye, but the other may look the same. Notice the reduced periphery that might not show up in typical in-clinic screening of visual fields.  This visual field test is called a Goldman 30-2 and is done on each eye.  It  should be a standard part of the assessment of all of the post-TBI/CVA patients.

Improving Ambient Visual Function

To improve function of the ambient system, binasal occlusion may be added to a patients glasses with or without mild base in prisms.  How does this help?

A person that is over-centrally focused has a difficult time seeing the entire word. They tend to see letters rather than the whole word which greatly reduces reading fluency and comprehension. Saccades also become less accurate due to the decreased awareness of the line of text  making the person lose their place frequently.

This can also improve posture and gait. As the brain becomes more aware of the ambient visual system, it is better able to correctly adjust gait and posture. Remember the tunnel?

Optometrists that offer this type of service are involved in neuro-optometry. The organization is called the Neuro-Optometric Rehabilitation Association. This is a multi-disciplinary organization that was started by ODs who wanted to understand brain injury better and exchange information with other providers of care in the  TBI community like OTs and PTs. There is a provider list on their website to help you find a NORA optometrist in your area.

Learn More

Learn more about this subject in a live course presented by Robert.  Its now available as a webinar too!! Hosted by PESI Education

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