A 23-year-old woman presents for evaluation of a severe headache that developed gradually over 5 days. She reports that this morning she found she is unable to walk because of weakness in both legs....

A 23-year-old woman presents for evaluation of a severe headache that developed gradually over 5 days. She reports that this morning she found she is unable to walk because of weakness in both legs. What is the most likely vessel to be involved?

A. Sigmoid sinus

B. Transverse sinus