A 29-year-old man is seen in the office after returning from a hiking trip in Colorado. He complains of feeling unwell and reports symptoms of fever, myalgia, headache, and nausea. Two days ago, he noticed a rash on his wrists and ankles that has now spread to his body. He recalls having had numerous insect bites during his trip. On examination, his blood pressure is 90/60 mmHg, pulse 100/min, and respirations 20/min. There are multiple 1-5 mm macules on his body and some of them have a hemorrhagic center consistent with a petechia. His neck is supple and fundi are normal. The heart sounds are normal, lungs clear, and legs are edematous. Cranial nerve, motor, and sensory examination is normal. A clinical diagnosis of Rocky Mountain Spotted Fever (RMSF) is made and he is started on appropriate therapy. Which of the following is the most common type of central nervous system (CNS) presentation in this condition?