As so many posts mentioned this is an ulnar n. problem. cool. But you also have to be able to distinguish between ulnar nerve at the hook of hamate vs ulnar nerve as it courses through the flexor carpi ulnaris.
with the Froment sign you know the deep branches of the ulnar nerve are being effected. This guy is on his bike and rides for 8-10 hours a day - pretty cray. But that's how you know its more likely compression from the handlebars at the hook of the hamate bone and not on the side from his flexor carpi ulnaris.
The adductor pollicis muscle is innervated by the ulnar nerve, giving this guy a difficult time holding a sheet of paper.
Most of intrinsic muscles of the hand are innervated by ulnar nerve - chronic compression at the hook of hamate could lead to nerve ischemia
Bicycle handlebar injury traditionally damages ulnar nerve @ the hook of the hamate bone
Why has no one commented about recurrent branch of median? Recurrent branch of the median nerve innervates all thenar muscles, with the exception of the adductor polis which is innervated by the ulnar.
Also the recurrent branch does not innervate interosseous muscles, thatโs ulnar.
Also also Fromentโs sign tests thumb adduction.
https://www.google.com/search?q=guyons+canal+syndrome+hamate&tbm=isch
submitted by โhello(429)
Guyon Canal Syndrome is due to an Ulnar Nerve lesions and is associated with bicycle handlebar use.
Also FINGER abduction and adduction is mediated by ulnar nerve. The patient is having trouble with FINGER abduction and adduction.
The Froment sign is testing ADDUCTOR POLICIS ACTIVITY, which is mediated by the ULNAR NERVE activity. It is NOT testing thumb opposition, which would be mediated by the median nerve.
See Froment sign