Understanding “Low Tone”
Written by Jennifer MacEachern (BHScPT, BPE)
Registered Physiotherapist With a special interest in Paediatrics
We live in a world defined by the “label” – a combination of words or phrases that are used to describe a person, a grouping, or a product. This is especially true in the healthcare system, where such terminology can be very confusing. The goal of this article is to help you, as a parent, to better understand what the label “low tone” means and how it may apply to your child.
“Your child has low tone….he/she is a floppy baby……your child is hypotonic”.
Taber’s Medical Dictionary defines tone as:
“…the normal tension or responsiveness (of muscles) to stimuli…the resistance of muscles to passive elongation or stretch…the ability of a muscle to resist a force for a considerable period of time without change in length.”
We can use the example of sitting in a chair. Think how you’d sit if you were sitting on a stool, something with no back or foot support. You’d sit up straight, helping to hold in place on the stool. You are still sitting still on your stool but you’ve had to increase your tone to prevent you f
rom falling off the stool. Now think of how you’d sit in a comfortable reclining chair, one that was well padded, with full back and head support. You’d become one-with-the-chair, decreasing your tone significantly. In these two scenarios you have intentionally increased and decreased your tone respectively. Think of it as having a sliding scale of sorts.
What does this really mean? In clearer terms, tone is that underlying current from our brains that allows our muscles to remain at the ready to respond to any input or stimulation. We all have tone. It’s what keeps us vertical even amidst the powerful and constant forces of gravity. It’s what allows us to hold our head up, keep our backs straight and stay up on our feet without having to think or concentrate about it. Each individual’s tone is different and there is a range of what is considered “normal”. What is also interesting is that within the range of normal there can be fluctuations in our tone dependent on the situational requirements.
rom falling off the stool. Now think of how you’d sit in a comfortable reclining chair, one that was well padded, with full back and head support. You’d become one-with-the-chair, decreasing your tone significantly. In these two scenarios you have intentionally increased and decreased your tone respectively. Think of it as having a sliding scale of sorts.
What about hypotonia? What does this mean? “Hypotonicity” has been described as:
“….reduced resistance to passive stretch; displayed as the inability to hold resting posture against gravity; limp, “floppy” extremities during passive movement.” 2
Hypo (indicating less than, below or under)1 and tonicity, when combined describe a situation where the tone of the muscle or the resistance to passive movement is decreased below the range of what is considered normal. We use the term Hypotonic when this oneness-with-the-chair, as above, is a more persistent state. It is now interfering with the normal day-to-day function of the individual, impairing their ability to produce a functional level of resistance to an imposed force (such as gravity or an action that is weight bearing). This hypotonicity is most notable, particularly in children with Down Syndrome (DS), when it comes to their motor skills: head control, trunk control, fine and gross motor skill acquisition, coordination, and oral motor control (suck/swallow, speech). Having hypotonia makes it more difficult to move, requiring increased input or stimulation and increased strength to obtain a functional level. A child with hypotonia must actually work harder, exert more energy and power to achieve the same result as a child without hypotonia.
No two children will ever present exactly the same, despite a similar diagnosis. Some have greater tone than others, making their muscles more responsive to input and it easier to move their bodies and gain control over their bodies in space. Unfortunately there is little we can do to alter that underlying resting state or tone. What we can do is manage it. In that, it is vital that the child be exposed to movement patterns that encourage the proper use of the muscles, that structure and alignment are protected and that the body is strong and responsive. For this early intervention is vital. Consultation with a developmental therapist: Physiotherapist, Occupational Therapist, Early Interventionist, Play therapist etc. will help teach you and your child normal movement patterns so that their bodies grow and develop, building on each skills set and advancing their strength and coordination. The label adds a challenge certainly, but does not have to be synonymous with a motor delay and abnormal movement patterns. You and a trained professional can advance your child’s motor skills so that they are able to achieve independent exploration of their environment as appropriate at each developmental stage.
Jennifer has worked exclusively in paediatrics for the past 15 years and is currently practicing in Newmarket, Woodbridge and Toronto. She has completed courses in NDT, NMES, CME (Medek), KinesioTape (K1K2), Theratogs, Myofascial Release, manual therapy, feeding and is an ADP Mobility Authorizer.
References:
1. Thomas, CL. Taber’s Cyclopedic Medical Dictionary 17th Edition. Philadelphia, PA: FA Davis Co, 1989
2. Umphred, DA. Neurological rehabilitation 2nd Edition. Toronto, ON: The CV Mosby Co, 1990