- A lesion of the PIN causes weakness of finger extension (finger drop) without wrist drop.
- The wrist deviates radially on extension due to weakness of the PIN innervated extensor carpi ulnaris muscle with preservation of the main trunk innervated extensor carpi radialis longus muscle.
- Some of the fingers may be affected more than others most often the ring and small fingers are selectively dropped, producing an abnormal posture which will superficially resembles an ulnar griffe (pseudoulnar claw hand).
- Sometimes, cervical radiculomyelopathy will also selectively drop the ring and small fingers (Ono's hand, myelopathy hand, pseudopseudoulnar claw hand).
- A PIN lesion is not associated with sensory changes.
- Neuropathy of the superficial radial nerve will cause pain and alterations of sensation in its
- distribution; it may be injured by tight bands around the wrist
Labels:
clinical sign
,
neurology