Monday, February 18, 2013

Sensory Week - The Vestibular System

The vestibular system is located in the inner ear and is responsible for our sense of movement, balance or equilibrium and spatial orientation. It provides information regarding the position of our head in space and acceleration and deceleration of movement. It is known to be one of the first sensory systems to fully develop in utero.

In her book, Sensory Integration and the Child, Dr. Ayres, the guru of sensory integration, an occupational therapist and developmental psychologist, explains:
The vestibular system is the unifying system. It forms the basic relationship of a person to gravity and to the physical world. All other types of sensation are processed in reference to this basic vestibular information. The activity
in the vestibular system provides a “framework” for the other aspects of our experience.
Vestibular input seems to “prime” the entire nervous system to function effectively. When the vestibular system does not function in a consistent and accurate way, the interpretation of other sensations will be inconsistent and inaccurate, and the nervous system will have trouble getting “started”.

As I learned in The Sensory Integrative Perspective Course, The vestibular system is like a news reporter. It reports new information as we move and as fibers in the ear change. 

The vestibular system also works with other related sensory systems including:
  • vestibular/auditory integration
  • vestibular/visual integration
  • vestibular/proprioceptive integration
There are varying types of vestibular processing difficulties including:
1. Gravitational Insecurity - The child has an "irrational" fear of falling during various types of movement. This may be when they are lifted in space, are flipped upside down, attempt jumping off of a curb or step. They do not like sudden movements and tend to move slowly and cautiously.
2. Intolerance to movement - The child vomits or has an upset stomach in a moving vehicle or becomes very upset with movement. These children may be considered Hyperresonsive (overresponsive) to movement.
3. Poor Registration or Hyporesponsiveness (underresponsive) to movement - Children often "seek" out input (jumping, spinning, swinging back and forth). They have difficulties holding still, show poor postural accommodations, are challenged with spatial orientation.
4. Decreased vestibular-ocular responses - poor eye movements and poor processing of visual input. For example, when the head moves right, the eyes move left, preserving the image on the center of the visual field.
5. Inadequate postural-ocular control - decreased extensor tone, poor concentration, decreased shoulder stability and eye-hand coordination, poor eye tracking, decreased stabilization of the head/neck/eyes/trunk.
6. Poor laterality, bilateral integration and sequencing - difficulties coordinating two sides of the body to work together, decreased ability to coordinate rhythmic sequences of movement, difficulties with symmetrical movements of both sides of the body (for example standing with right arm and right leg in front, jumping and switching so left arm and left leg are in front and then alternating in a smooth, rhythmic pattern), challenges with asymmetrical movements of both sides of the body (same as above, but begin with left arm and right leg - asymmetrical)

When children are not processing vestibular information properly, they may exhibit decreased balance and trunk control. Difficulties with successful interaction with their environment can also inhibit the execution of fine motor (i.e., handwriting), visual motor (i.e., legos), gross motor (PE class), and self-care activities (i.e., tilting the head back to rinse shampoo out of their hair). Struggles with vestibular processing are often related to the inability to regulate arousal level required to maintain focus and attention. There have also been links to decreased REM sleep and depression in regards to inhibited vestibular processing.

Here is an example of how a child with challenges related to their vestibular system may have adversities to handwriting. Vestibular processing affects spatial organization needed for writing; directionality, right/left issues. They may be unable to coordinate both sides of the body to perform writing, for example, hold the paper with one hand and write with the other, or as mentioned above, bilateral coordination. Decreased extensor tone inhibits overall muscle tone, proximal stability and postural control, all needed to sit with an upright posture and engage in the fine motor act of handwriting. Finally, vestibular input can also impact head and eye coordination necessary for writing. 

It is also important to consider inter-related or alternative reasons why children are having difficulties that may present themselves as challenges with vestibular functioning:
  • Limited experience or exposure
  • Neuromotor impairment
  • Muscle weakness
  • Decreased range of motion
  • Visual or hearing impairment
  • Emotional Disorder (ED)
  • Reactive Attachment Disorder (RAD) 
Some activities that target the vestibular system:
  • Swinging - the fastest and most effective way to provide vestibular input. Swinging in an orbital or circular motion is generally excitatory for the nervous system. Swinging in a slower, linear plane (front to back or up and down) is generally more calming for the nervous system). 
**When swinging children, it is extremely important that their responses are monitored. Indicators that the child is over-stimulated or not tolerating the movement include: red face, pallor color, nausea, or the child resisting the movement. 
  • Rolling in a barrel or rolling down a hill
  • Sliding down a slide
  • Bouncing or jumping on a ball or trampoline
  • Amusement rides
 If you think that your child or one of your students may be exhibiting vestibular processing challenges, which can impact many areas of their life, it is important to contact an occupational therapist. The OT will assess the child's sensory integration and, if needed, determine what sensory strategies will be effective in assisting your child in reaching an optimal state of functioning.

1 comment:

  1. This is an awesome article. My OT intern and I have been looking for research on this subject and have found some but nothing substantial. If you'd like I can forward the research to you, contact me via my blog and give me your email address and I'll send you the research if you're interested.