What is “Tone” and What Does it Mean to Me?

“Tone” is an umbrella term to refer to resting Muscle Tone and Spasticity. Both these terms are similar in what they mean but they have very important differences! 

Let’s break them down.

What is Muscle Tone?

Muscle tone is the natural level of tension in a muscle at rest. It helps us maintain posture and keeps our muscles ready for movement. You don’t usually notice your muscle tone unless something changes it. 

Muscle tone that is increased at rest may feel like a muscle that is contracting, like your bicep when you try to pick something up. At rest this can make the muscle harder to lengthen, but it may be easier to perform an action like holding something or standing. 

Muscle tone that is decreased at rest may feel like a muscle that is really soft and relaxed. At rest this can make the muscle really easy to move, but it can be much harder to perform a task since the muscle has a hard time contracting. 

What is Spasticity?

Spasticity is a specific type of increased muscle tone. This type of muscle tone is seen when a muscle is moved or stretched fast or suddenly. 

In simple terms, spasticity is an overactive stretch-reflex response. Muscles become tight or stiff during fast or unanticipated movements and typically resist being stretched or moved suddenly. 

The stretch reflex refers to the contraction of a muscle in response to its passive stretching. When a muscle is stretched, the stretch reflex regulates the length of the muscle automatically by contracting the muscle before it goes too far to prevent injury. 

This reflex is normally regulated by something called Supraspinal Inhibitory Control. This is when the brain sends signals to stop the stretch reflex from starting when we don’t want it to, like when we are about to move. 

Supraspinal Inhibitory Control is typically impaired in conditions that impact the central nervous system, such as stroke, multiple sclerosis, spinal cord injury, and cerebral palsy to name a few. 

What Does Tone Mean to Me? 

Muscle tone can increase and decrease throughout an individual's rehabilitation, neither increasing or decreasing is good or bad. 

Tone changing can actually often be seen as a sign of motor recovery! This is described by the Brunnstrum Stages of Motor Return. These stages outline a potential template that changes in tone would be expected. 

The Stages are as Follows:

Stage 1: Flaccidity

-Muscles of the affected area have decreased muscle tone. 

Stage 2: Appearance of Spasticity

Stage 3: Increased Spasticity.

Stage 4: Decreased Spasticity.

Stage 5: Complex Movement Combinations

-Spasticity has decreased to the point where you have the ability to use muscles one at a time. 

Stage 6: Spasticity Disappears.

Stage 7: Normal Function Returns.

Important Note: Not everyone experiences these stages in the same way, order, or time. However they provide a general timeline for reference. 

In summary, “Tone” is a short word that refers to a lot of complex things that we experience with our body when living with a neurological condition. Understanding what it means and how it relates to you is helpful in having an effective rehabilitation and wellness journey.  

References: 

Bannister K, Dickenson AH. Central Nervous System Targets: Supraspinal Mechanisms of Analgesia. Neurotherapeutics. 2020;17(3):839-845. doi:10.1007/s13311-020-00887-6

Bhattacharyya KB. The stretch reflex and the contributions of C David Marsden. Ann Indian Acad Neurol. 2017;20(1):1-4. doi:10.4103/0972-2327.199906

Trompetto C, Marinelli L, Mori L, et al. Pathophysiology of spasticity: implications for neurorehabilitation. Biomed Res Int. 2014;2014:354906. doi:10.1155/2014/354906