A 56-year-old male with a history of hypertension for over 10 years was admitted to the emergency department due to sudden headache and hemiplegia after defecation, lasting 4 hours, accompanied by vomiting twice. Physical examination: BP 26/14 kPa (195/105 mmHg), left upper and lower limb muscle strength grade 0/5, hypotonia, and left-sided hemihypesthesia. [Hypothetical scenario] If the patient suddenly becomes unconscious 10 hours after admission, with BP 26/14 kPa, comatose state, no response to orbital compression, pupil diameter: right 3.5 mm, left 2.5 mm, absent pupillary light reflex, and bilateral Babinski sign (+), the most likely diagnosis and prognosis are: