The painless thumb weakness and the ultrasound finding in the muscles




A 47 year old patient is referred to your lab. The referral diagnosis is posterior interosseus syndrome. 


As you look at the posterior interosseus nerve on its course through the supinator muscle, you suddenly notice what you can see in the first video below. You get curious and look at the extensor muscles of the forearm a little more distally (second video).


  1. What is the name of this phenomenon?
  2. What is the underlying cause?
  3. In which disorders can you find it and in which disorders is it a prominent   feature?
  4. How does that now fit in with the referral diagnosis?



Answers will follow on this page by June 1st smile


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