Compass is still being developed and is effectively in beta. Some content and features may be incomplete, change, or not work as expected.

Content is anchored to trusted sources where available, but Compass has not yet been clinically reviewed. It provides general information rather than medical advice.

Feedback helps us identify gaps, errors, usability problems and opportunities to improve Compass over time.

How Compass is developedGive feedback

Movement and daily function

Muscle cramp

A sudden, painful tightening of a muscle that holds for a while and then releases.

What it means

Common in ALS/MND, often at night or after activity, and frequently in the calves, hands or abdomen.

Why you might hear it

  • It is asked about routinely at clinic visits.
  • It is easy to confuse with spasticity, which is a different thing.

People who may help

Where Compass goes into this

About this explanation

These are plain explanations of words you may come across, not advice about your own situation. Where a word matters to a decision, the question pages go into it properly, and your own team is the place to take it.