This system, like other sensory systems, has a defensive component. When an infant feels herself falling, she responds to this vestibular sensation as if saying, “Uh, oh!” She extends her arms and legs, groping for something to grab. Her whole body responds in this automatic, self-protective reflex.
As a child grows, her brain integrates reflexive responses in a process called reflex maturation. She learns to discriminate vestibular sensations. She seems to say, “Aha! I’m learning to sense what direction I’m going in and whether my movement is fast or slow.”
Now, when movement sensations help her perceive that she is off center, she learns how to regain her balance. She learns to “stand on her own two feet,” in an upright position, against the pull of gravity. She learns to differentiate her body movements so she can function with an economy of motion.
She can also discriminate among the sounds vibrating in her inner ear, and she learns to listen. She can coordinate her own body movements with visual sensations, and she learns to discriminate what she sees.
She learns to enjoy all kinds of movement. One kind is linear movement—back-and-forth, side-to-side, or up-and-down. Slow and low linear movement, which does not challenge gravity, is usually soothing. Parents have known since time immemorial that they can comfort a baby in a rocking chair, in a cradle, or with gentle bounces. In fact, many children (and adults) rock themselves when they are upset, as a kind of tranquilizing self-therapy.
Another kind of movement is rotary—moving around and around. Examples of rotary movement include spinning oneself on a tight axis, (e.g., planting one foot on the ground and turning rapidly), riding on a merry-go-round, or swinging high on a long-roped swing. Most children enjoy twirling on a tire swing—even to the point of getting dizzy. Rotary movement stimulates the vestibular system. Usually, it feels good, and that’s why it is so much fun!
THE OUT-OF-SYNC VESTIBULAR SENSE
Vestibular dysfunction is the inefficient processing in the brain of sensations received through the inner ear. The child with a vestibular problem has difficulty processing information about gravity, balance, and movement through space.
The child may not develop the postural responses needed to keep upright. She may never have crawled or crept and may be late learning to walk. She may sprawl on the floor, slump when she sits, and lean her head on her hands when she is at the table.
As she grows, she may be awkward and uncoordinated at playground games. She may fall often and easily, tripping on air when she moves, bumping into furniture, and losing her balance when someone moves her slightly off center.
As eye movements are influenced by the vestibular system, she may have visual problems. She may have inadequate gaze stability and be unable to focus on moving objects or on objects that stay still while she moves. At school, she may become confused when looking up at the board and down to her desk. Reading problems may arise if she hasn’t developed brain functions imperative for coordinating left-to-right eye movements.
Vestibular dysfunction may also contribute to difficulty processing language—a great disadvantage in everyday life. The child who misperceives language may have problems learning to communicate, read, and write.
Many movements provide a calming effect. The out-of-sync child, however, can’t always calm herself because her brain can’t modulate vestibular messages. Difficulty moving smoothly interferes with her behavior, attention, self-esteem, and emotions. The child with an inefficient vestibular system may have modulation, discrimination and motor problems affecting her every move.
Sensory Modulation Disorders
VESTIBULAR OVERRESPONSIVITY—“OH, NO!”
Vigorous movement, or the possibility of being moved, causes the child with vestibular overresponsivity to respond negatively and emotionally, or to become overexcited.
This modulation disorder means that her brain can’t regulate movement sensations. Her vestibular system is on overload. Particularly when her head or eyes move, her brain is bombarded with sensory stimuli that it can’t organize. Two types of vestibular overresponsivity are intolerance to movement and gravitational insecurity.
INTOLERANCE TO MOVEMENT—“NO, DON’T!”
The child who is overresponsive to vestibular sensations may be intolerant of movement. Faulty processing causes aversive responses. “Oh, no, don’t make me move! Moving quickly is too much for me.”
HOW INTOLERANCE TO MOVEMENT AFFECTS A CHILD’S BEHAVIOR
A Typical Child A Child with Intolerance to Movement
Noah’s favorite activities are movement and music. Today, the preschoolers play “Noncompetitive Musical Chairs.” In this game, no chair is ever taken away. The object is to move around the chairs while the music plays and sit on any seat when the music stops. Everyone plays the whole time; no one is ever “out.” When the music starts, Noah jumps up and circles the chairs with the other kids. When the music stops, he slithers into a chair. Once, he lands on another child’s lap, but he looks around fast, sees an empty chair, and runs to it. Safe! Sean, four, dislikes most music and movement activities. “Noncompetitive Musical Chairs” makes him especially uncomfortable. While the other children run freely around the circle, he inches along, clinging to the seats of the chairs. By the time he has circled the chairs twice, his forehead is sweaty, and his stomach is churning. The music finally stops, and Sean sits down with a sigh of relief. When the music resumes, he remains seated.
For her, linear movement is distressing, especially when rapid. Riding in a car—particularly in the back seat—often causes car sickness. She may avoid riding a bicycle, sliding and swinging at the playground, or just walking down the street.
Rotary movement can be even more distressing. She may become easily dizzy and nauseated on a tire swing. Even watching someone or something spinning can make her feel queasy. Moving in circles may make her head ache and stomach hurt.
If she avoids moving, she may lose the ability to keep up with others. She may become breathless and easily fatigued. Her motor planning skills and coordination may suffer, because she can’t practice them with confidence.
GRAVITATIONAL INSECURITY—“I’M FALLING!”
Being connected to the earth is a primal need for survival. The vestibular system tells us where we are in relation to the ground. The trust that we are attached to the earth is called gravitational security.
Usually, a child has inner drive to experiment with gravity. Jumping, swinging, and somersaulting, she can relinquish her grip on earth for an instant, because she knows she will always return. With this basic sense of stability, she can develop emotional security.
The child with poor modulation may not enjoy this sense of stability. She feels vulnerable if her feet leave the ground. Lacking a basic sense of belonging to the earth, she has gravitational insecurity, or “G.I.”
Gravitational insecurity is abnormal distress and anxiety in response to falling or the possibility of falling. It is a primal fear. It occurs when the child’s brain overreacts to changes in gravity, even as subtle as standing up.
Movement for this child is not fun; it is scary. When her head moves, she responds, “I’m falling! I’m out of control!” She overreacts with a fight-or-flight response.
The “fight” response plays out as negative, defiant behavior, particularly when she is passively moved. She may resist being picked up, rocked, or pushed in the stroller. She may become angry and stubborn when someone suggests riding in the car or sledding down a hill.
The “flight” response plays out as extreme caution or avoidance of movement. She prefers keeping her head up and feet down, firmly planted. She may avoid playing “Ring Around the Rosy,” riding a bicycle, sliding and swinging. She may be fearful of unstable surfaces, such as a sandy beach or a climbing net at the playground. She may avoid novel experiences, such as visiting a friend’s house, because any place other than home is unpredictable.
The child with this terror tends to be inflexible and controlling. She
often has social and emotional problems, because she is so worried about falling that she always feels vulnerable when around other people. The result is that she can’t get organized for other tasks, such as playing and socializing.
HOW GRAVITATIONAL INSECURITY AFFECTS A CHILD’S BEHAVIOR
A Typical Child A Child with Gravitational Insecurity
With his class, Jack, nine, goes for a hike up a little mountain. At one point, a thick vine hangs down from a branch. Jack takes a turn swinging on the vine, screaming, “Tarzan!” Jack’s efficient vestibular system permits him to enjoy exploring gravity as he swings and soars through the air. The day his class goes hiking, Brad, nine, watches each step. He is grouchy, silent, and slow. He stands aloof while his classmates swing on a vine. When it’s his turn, he takes the vine reluctantly. He can’t move. The others cry, “Come on! What’s your problem? It’s fun!” Brad senses that if his feet leave the ground, he’ll fall into the void. Saying, “I’m really not interested in this stupid game,” he drops the vine and stalks away.
VESTIBULAR UNDERRESPONSIVITY—“HO, HUM.”
Another child may be underresponsive to movement experiences. She does not respond negatively; she simply does not seem to notice. As an infant, she may have been “such an easy baby,” always ready to curl up in anyone’s arms, always ready for a long, long nap. As she matures, she seems to lack inner drive to move actively. Although she requires extra movement to “get in gear,” this child does not usually seek movement. Once started, however, she may have difficulty stopping.
Also, the child may be oblivious to the sensation of falling. She cannot respond efficiently with protective extension, i.e., extending a hand or a foot to catch herself. Many children with autism with this difficulty may have bruises because of frequent falls.
HOW VESTIBULAR UNDERRESPONSIVITY AFFECTS A CHILD’S BEHAVIOR
A Typical Child A Child with Underresponsivity
Jeff, thirteen, comes to the pool for aquatic therapy to strengthen his leg, which he broke while skiing last winter. On the concrete pool deck, he slips on a puddle and reacts immediately to catch himself, reaching for the wall so he doesn’t fall and break the other leg. That’s all he needs. Cameron, a thirteen-year-old with autism, comes to the pool for aquatic therapy. Lumbering toward his recreational therapist, he slips on a puddle. Unaware of the sensation of falling, and slow to protect himself, he ricochets off the wall and collapses on the pool deck. The therapist rushes to his side and guides him into the soothing water before he has a meltdown.
VESTIBULAR CRAVING—“MORE!”
The child who craves vestibular sensations never seems to get enough of movements that are sufficiently satisfying for others. The child has an increased tolerance for movement. She seeks and enjoys a great deal of vigorous activity to satisfy her sensory needs.
To get vestibular sensations, the child may seek to resist gravity in unusual ways. For instance, she may assume upside-down positions, hang over the edge of her bed, or place her head down on the floor and pivot around it.
The child may frequently seek intense movement sensations, such as jumping from the top of the jungle gym, or running fast when a sedate pace would do. Climbing may be her passion; for the sensory craver, everything is a ladder.
She may crave linear movement and enjoy rocking or swinging for exceptionally long times. She may especially seek rotary movement, such as twirling in circles, shaking her head vigorously from side to side, or spinning on the playground merry-go-round or tire swing.
She may flit and dart from one activity to another, always seeking a new thrill. Her attention span may be short, even for activities she enjoys. Although she may be constantly on the go, she may move without caution or good motor coordination.
HOW SENSORY CRAVING AFFECTS A CHILD’S BEHAVIOR
A Typical Child A Child with Sensory Craving
Justin, three, is at the swim center with his mother. He paddles in the kiddie pool, occasionally pausing to watch the big kids climb the ladder to the high diving board and jump into the water. When it is time to go home, he takes his mother’s hand and says, “Let’s go see that big ladder.” He looks up, longingly. It’s so high! So scary! Someday he’ll be big and brave enough to climb it, but not yet. Billy, three, is at the swim center with his mother. He starts to jump into the big pool, but she restrains him and guides him into the kiddie-pool enclosure. While she and the lifeguard discuss scheduling Billy’s first swimming lesson, he escapes. He clambers up the high diving board. He teeters on the edge, ready to jump into the deep water. His mother notices his absence, springs up the ladder, and catches him just before he falls.
HOW THE VESTIBULAR SENSE AFFECTS EVERYDAY SKILLS
The vestibular sense gives us information necessary for many everyday skills:
Gravitational security (see p. 120)
Movement and balance
Muscle tone
Bilateral coordination
Praxis (motor planning)
Vision and hearing (see Chapters Six and Seven)
Emotional security
Movement and Balance
Automatic, coordinated movement and balance are possible when the central nervous system connects vestibular sensations with other sensations. Movement and balance are sensory-based motor skills, not senses per se.
The vestibular system tells us which way is up, and that up is where we want to be. When we’re upright, we’re alert and in control. To keep upright, we make subconscious, physical adaptations, called postural background adjustments. These subtle adjustments allow us to stabilize our bodies, to correct and maintain our balance, and to move easily.
The child with vestibular dysfunction has problems with movement and balance. She moves too little or too much, with too much or too little caution. Her movements may be uncoordinated and awkward.
HOW MOVEMENT AND BALANCE AFFECT A CHILD’S BEHAVIOR
A Typical Child A Child with Vestibular Dysfunction
When Jeremy, ten, first got his skateboard, he fell frequently, but he has gradually learned to adjust his weight to keep his balance. He sets up obstacle courses in the street, with ramps and traffic cones, and invites his pals to try new tricks. When Joe collides with him and throws him off balance, Jeremy can usually land on his feet. Joe, ten, can’t quite get the hang of riding his skateboard, although he practices every day and works hard to master this skill. Yet he still crashes into Jeremy’s ramps and traffic cones, and even into Jeremy. Usually Joe feels himself falling but can’t stop himself, because his postural background adjustments are ineffective and he keeps losing his balance.
Muscle Tone
Muscle tone is the degree of tension normally present when our muscles are in a resting state. (Muscles never relax completely unless we are unconscious.) Muscle tone is a sensory-based motor skill and is a component of normal movement patterns. When we have good muscle tone, we usually take it for granted.
If you lead a normal life and exercise sometimes, you probably have adequate tone when you are resting. If you exercise regularly, you probably have firm tone. If you are a “couch potato,” you probably have low tone. And, furthermore, if you are a couch potato—because the apple does not fall far from the tree—chances are that your child is a “potato chip.”
The vestibular system, along with the proprioceptive system, strongly affects tone by regulating neurological information from the brain to the muscles, telling them exactly how much to contract, so that we can resist gravity to perform skilled tasks. Usually, our muscle tone is neither too tight nor too loose; it is just right, so we don’t have to use much effort to move our bodies or keep ourselves upright.
HOW MUSCLE TONE AFFECTS A CHILD’S BEHAVIOR
A Typical Child A Child with Vestibular Dysfunction
Scotty, four, pulls on his socks and his high-top sneakers. He doesn’t yet know how to tie his shoes. He grips with his toes to keep the loose sneakers on his feet and thumps to his father for help. His father sa
ys, “You’re growing so fast, soon you’ll be able to tie your shoes all by yourself.” Scotty says, “But I can make them twinkle. Want to see, Daddy?” He springs up, and when he lands, the heels of the sneakers light up. Ted’s father parks him on the bed and tries to push his limp feet into a pair of socks. “Can you help me, son?” he asks. “It seems as if I’m doing all the work here.” Ted tries to cooperate, but his feet don’t always do what he wants them to do. Finally, the socks are on. While his father wiggles Ted’s feet into his sneakers, Ted sprawls backwards on the bed. “Can you help me, please?” asks his father. “Too tired,” says Ted.
The child with vestibular dysfunction may have a “loose and floppy” body, or low tone. This is a postural disorder that interferes with her movement. Nothing is wrong structurally with her muscles, but her brain is not sending out sufficient messages to give them “oomph.” Without that energizing oomph, the child’s muscles lack the readiness or tension necessary to move with ease.
The sensory slumper may often lay her head on the table, or sprawl on the floor, or slouch in the chair. She may have difficulty turning knobs and pressing levers. She may handle objects loosely or with a very tight grasp in order to compensate for the underlying low muscle tone. She may tire easily, because resisting the pull of gravity requires a great deal of energy.
Bilateral Coordination
Bilateral (from the Latin for “both sides”) coordination means that we can use both sides of the body to cooperate as a team. A well-regulated vestibular system helps us to integrate sensory messages from both sides of our body.
By the age of three or four, a child should be crossing the midline. For the child who avoids crossing the midline, coordinating both body sides may be difficult. When she paints at an easel, she may switch the brush from one hand to the other at the midway point separating her right and left sides. She may appear not to have established a hand preference, sometimes using her left and sometimes her right to eat, draw, write, or throw. It may also be hard to survey a scene or to track a moving object visually without stopping at the midline to blink and refocus.
The Out-of-Sync Child Page 13