Testing for spasticity involves assessing the velocity-dependent increase in muscle stretch reflexes, which is often associated with increased muscle tone. Here's how it's typically done, incorporating information from the reference:
Understanding Spasticity
According to Jim Lance (1980), spasticity is defined as a velocity-dependent increase in muscle stretch reflexes, coupled with increased muscle tone, as part of upper motor neuron syndrome. [1] It's crucial to understand this definition as it forms the basis for how we assess spasticity.
Clinical Assessment Methods
The primary method to test for spasticity is through clinical examination, focusing on:
-
Passive Range of Motion Assessment:
- The examiner moves the patient's limb slowly and then quickly, observing for resistance.
- Spasticity presents as increased resistance to rapid passive movement, especially at the beginning of the range. This is known as "catch" or "clasp knife" response.
- If there is more resistance felt during the rapid movement compared to slow movement, it is suggestive of spasticity.
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Modified Ashworth Scale (MAS):
- This is the most universally accepted clinical tool for quantifying spasticity. [1]
- It's a subjective scale that grades the muscle tone based on the resistance felt during passive movement of a limb.
- The scale ranges from 0 to 4, where 0 means no increase in tone and 4 indicates rigid tone.
The Modified Ashworth Scale Explained
| Grade | Description |
|---|---|
| 0 | No increase in muscle tone. |
| 1 | Slight increase in muscle tone, manifested by a catch and release or by minimal resistance at the end of the range of motion. |
| 1+ | Slight increase in muscle tone, manifested by a catch, followed by minimal resistance throughout the remainder of the range of motion (less than half). |
| 2 | More marked increase in muscle tone throughout most of the range of motion but affected parts are easily moved. |
| 3 | Considerable increase in muscle tone, passive movement is difficult. |
| 4 | Affected part(s) rigid in flexion or extension. |
How to Use the MAS
- Position the patient comfortably.
- Passively move the limb through its range of motion, first slowly and then quickly.
- Note the point of increased resistance or "catch".
- Assign a score based on the description in the table above.
- Repeat for different muscle groups as needed.
- Observation of Other Clinical Signs:
- Clonus: Involuntary, rhythmic muscle contractions when stretching the muscle.
- Hyperreflexia: Exaggerated deep tendon reflexes, often assessed using a reflex hammer.
- Muscle weakness: Spasticity is often associated with muscle weakness.
- Abnormal posture: Spasticity can lead to abnormal postures, like clenched fists, adducted thighs, and plantar flexed feet.
Practical Insights:
- Repeatability: It’s important to be consistent in technique and speed of movement during examination.
- Context: The results of spasticity tests should be interpreted within the patient's overall clinical presentation, medical history, and other neurological examination findings.
- Differentiation: Spasticity should be differentiated from other conditions with increased muscle tone such as rigidity (as seen in Parkinson’s disease) which is not velocity dependent.
Conclusion
Testing for spasticity primarily involves a clinical examination that incorporates the passive range of motion assessment, use of the modified Ashworth scale, and the observation of other signs like clonus, hyperreflexia and abnormal postures. The modified Ashworth scale is the most universally accepted clinical tool for measuring the increase of muscle tone. [1]
