Brain abscess

A 12-year-old boy is brought to the emergency department by his mother because of severe frontal headaches and vomiting. His medical history is relevant to a recent bacterial sinus infection. Upon medical interrogation,  the mother reports that before his condition worsened, the boy had a very aggressive and reckless behavior. Physical exam shows mental status deterioration, speech apraxia, and unilateral body hemiparesis. His temperature is 38.4°C (101.2°F), pulse is 100/min, respirations are 17/min, blood pressure is 110/70 mmHg. At this point, requesting which of the following is the most appropriate next step?