A 25-year old woman, who has been out of work since dropping out of college early, arrived at the Emergency Department with a sudden onset of left-sided hemiparesis. Her father mentioned that she had been hospitalized for chest pain 4 years ago, but he did not have any further information about the admission. She occasionally smokes cigarettes when she can afford them.
During the examination, she had a flushed face and livedo reticularis on her thighs. She was 1.7 m tall and had scoliosis. Her blood pressure and heart sounds were normal. Her Mini-mental scale score was 26/30. She had a slight left-sided facial palsy and pyramidal weakness in her left limbs. Her speech and sensory system were normal.
What is the most probable underlying diagnosis?