Reason: stab wound of right upper arm at level of lower third of humerus with radial nerve palsy. R/O radial nerve laceration History: pain and wrist drop There is circumferential fluid within the tendon sheath of the long head of the biceps indicating a tenosynovitis. There is decreased linear signal abnormality traversing the subcutaneous tissue along the lateral and posterior aspect of the arm at the level of the mid to distal diaphysis of the humerus which likely represents scarring from prior injury/laceration. There is a skin marker in the overlying area presumably corresponding to the patient's area of prior injury. There is an 11 x 10 mm focus of increased signal abnormality on fluid sensitive sequences at the expected location of the radial nerve, interposed between the brachialis and medial head of the triceps musculature medial to the aforementioned scarring from prior injury which is nonspecific and may represent granulation tissue or perhaps a small seroma/hematoma, however, this is incompletely characterized on this noncontrast examination (image 10; series 6). The radial nerve is indistinct and poorly visualized and the surrounding area and may be disrupted. No bone marrow signal abnormality is identified. There is increased signal abnormality within the extensor musculature which likely represents subacute denervation injury (image 25; series 13). The imaged musculature of the right arm is otherwise unremarkable.
1. 11 mm nonspecific focus of increased signal abnormality at the expected location of the radial nerve at the level of the distal humeral diaphysis which is incompletely characterized but may represent granulation tissue or perhaps a small seroma/hematoma. The radial nerve is poorly visualized in the adjacent area and is likely disrupted. 2. Increased signal abnormality within the imaged extensor musculature is likely related to subacute denervation injury.