Question

A 65-year-old man presents with dry mouth and difficulties rising from a chair, climbing stairs, and walking. His symptoms started about 1 year ago, are worse in the morning, and improve with exercise. He is a heavy smoker and was recently diagnosed with lung cancer.

What is the most likely underlying mechanism of his weakness?

1. Infiltration of the nerves
2. Spinal cord compression
3. Spinal cord metastasis
4. Paraneoplastic
5. Nicotine poisoning

Answer 1

The most likely underlying mechanism of weakness in this 65-year-old man is paraneoplastic syndrome caused by his lung cancer.

Step-by-step explanation:

The most likely underlying mechanism of weakness in this 65-year-old man is paraneoplastic syndrome caused by his lung cancer.

Paraneoplastic syndrome refers to a group of signs and symptoms that occur in cancer patients due to substances produced by the tumor or an immune response to the tumor.

In this case, the patient's muscle weakness is likely due to autoantibodies that are produced by the immune system in response to the lung cancer, which cross-react with the nerves and disrupt their function.