A
Immediate surgical exploration of the radial nerve
B
Magnetic Resonance Imaging (MRI) of the humerus
C
Immediate Electromyography (EMG)
D
Observation and expectant management for 3-4 months
Explanation:The correct option is 'd'. A secondary (iatrogenic) radial nerve palsy occurring after closed reduction of a closed humeral shaft fracture is generally treated with observation, much like a primary palsy. Over 90% of these will recover spontaneously. Immediate exploration is typically reserved for open fractures, vascular injuries, or failure to recover after 3-4 months (at which point an EMG is useful to assess for reinnervation).
Reference: Shao YC, Harwood P, Grotz MR, Limb D, Giannoudis PV. Radial nerve palsy associated with fractures of the shaft of the humerus: a systematic review. J Bone Joint Surg Br. 2005;87(12):1647-1652.