A nurse in an emergency department is caring for a client who had a seizure and became unresponsive after stating she had a sudden, severe headache and vomiting. The client's vital signs are as follows: blood pressure of 198/110 mm Hg, pulse of 82/min, respirations of 24/min, and a temperature of 38.2 C (100.8 F). Which of the following neurologic disorders should the nurse suspect?