A 50-year-old male presents with persistent burning pain and numbness in the right groin and upper thigh, 3 months after undergoing inguinal hernia repair surgery. The pain worsens with activity and is associated with sensory loss in the affected areas. Physical examination reveals decreased sensation in the groin and upper thigh, with no evidence of recurrent hernia or masses. The clinical findings are suggestive of genitofemoral nerve injury, and the physician decides to confirm the diagnosis with further testing. Which of the following diagnostic tests is most useful in confirming genitofemoral nerve injury?
