49 years old female patient seeks medical care with the story of diplopia and left eye ptosis in the previous three weeks. She also reports difficulty to walk, having many times fallen over, especially during night time. There is also dysarthria, dysphagia and difficulty with chewing. Upon examination, she presents isochoric and photo reactive pupils and general paresis (4/5). Electromyoneurography and Computed tomography (CT ) of the chest were requested.

Question:
Based on the history and the image, one can conclude that the most likely diagnosis is: