Are twitches that are caused by action/flexing or tension in muscle always of malignant cause like als?no dr can tell me and i am scared.it's in thumb

Muscle twitch.: Generally speaking, there are benign causes of muscle twitching as you describe. So while there may be a cause for this muscle twitching, it does not have to be a malignant cause by guarantee.

Isolated: muscle twitches like you describe are quite benign and are usually related to FATIGUE (eg" Repetitive movement) Hope this helps! Dr Z