Differential Diagnosis for a 74-year-old man with inability to extend fingers and altered sensation after a fall
- Single most likely diagnosis:
- Radial nerve injury: The patient's inability to extend the fingers of the right hand, along with altered sensation on the palmar aspect, suggests a radial nerve injury. The radial nerve controls finger extension and supplies sensation to the back of the hand, but the palmar aspect sensation could be affected if there's a more proximal injury or involvement of other nerves. The mechanism of injury, with the arm jammed between the floor and body, could have caused compression or damage to the radial nerve.
- Other Likely diagnoses:
- Posterior interosseous nerve (PIN) injury: A branch of the radial nerve, the PIN specifically controls finger extension. An injury to this nerve could result in the inability to extend fingers without affecting wrist extension, as the extensor carpi radialis longus (which helps in wrist extension) is innervated before the PIN branches off.
- Combined nerve injury: Given the altered sensation on the palmar aspect, which is typically supplied by the median nerve, there could be a combined injury involving both the radial and median nerves.
- Do Not Miss diagnoses:
- Compartment syndrome: Although less likely given the time frame and specific symptoms, compartment syndrome is a medical emergency that can result from increased pressure within a muscle compartment, leading to nerve and muscle damage. It's crucial to consider this diagnosis due to the potential for severe and irreversible damage if not promptly treated.
- Vascular injury: An injury to the blood vessels supplying the arm could lead to ischemia and nerve dysfunction. This would be a medical emergency requiring immediate intervention.
- Rare diagnoses:
- Neuropraxia or axonotmesis of other nerves: While the clinical picture suggests radial nerve involvement, other nerves could be affected, leading to similar symptoms. These would be less common given the specific mechanism and presentation.
- Fracture or dislocation with nerve entrapment: Although the question does not mention significant trauma to the bones, a fracture or dislocation could potentially entrap nerves, leading to the observed symptoms. This would be less likely without other signs of fracture or dislocation but should be considered in the differential diagnosis.