Following a stroke patients may present with abnormal tone which may be decreased (hypotonus), increased (hypertonus) or a combination of the two. A combination of the two occurs where there is increased tone in one muscle group and decreased tone in another.
Tone may be increased temporarily by pain, discomfort, anxiety, effort and certain body positions.
Hypotonus
- Low-toned muscles are floppy and sag away from their bony connections leaving the associated joints unsupported and unstable.
- Low-toned limbs feel heavy and drop against gravity when handled if insufficient support is given. The muscle groups will feel flabby to handle and little or no resistance will be felt through the range of the movement. Great care must be taken to ensure adequate support of joints throughout their range of movement to prevent trauma, particularly to the shoulder.
Hypertonus
- High-toned muscles are tense and bulky, with tendons visible beneath the skin. Joints spanned by high tone muscles will assume a shortened position rendering the patient unable to relax.
- High-toned muscles will resist movement and feel tight.
Tone diagrams: these findings may be recorded using a tone diagram where high-tone muscles are shown with a (+) and low-tone muscles with a (-).
Base of support (BOS) is the surface area supporting the body or body part. A larger base of support e.g. lying down, allows greater muscle relaxation and therefore decreases muscle tone. A smaller base of support e.g. standing up, encourages more activity in muscles and therefore increases muscle tone.
By manipulating a patient’s base of support it is possible to alter their presenting patterns of muscle tone.
For more information on managing muscle tone visit STARS AM 19: Management of tone and spasticity after stroke: a role for everyone
Page last reviewed: 25 Feb 2021
