This patient has symptoms consistent with encephalitis (obtundation, fever, elevated cerebrospinal fluid [CSF] leukocyte count) and should undergo electroencephalography (EEG). Recent consensus guidelines promote standardized evaluation for encephalitis, which includes lumbar puncture, brain MRI, and EEG. EEG is indicated to confirm the diagnosis of encephalitis, provide information that may help identify a causative organism, and assess the need for antiepileptic therapy. Nonconvulsive seizures, defined as the presence of seizure activity on EEG in the absence of myoclonic movements or other clinical evidence of seizures, could contribute to alterations in consciousness. Nonconvulsive status epilepticus may be focal or generalized and has been reported with viral and autoimmune encephalitides. Nonconvulsive status epilepticus in patients with encephalitis is associated with a delay in initiating antiepileptic therapy and an increased risk for death.

Cerebral edema is a poor prognostic factor in encephalitis, and patients with evidence of increased intracranial pressure based on neuroimaging or increased opening pressure are best managed in an intensive care setting. The opening CSF pressure for this patient is within normal limits, indicating the absence of cerebral edema or increased intracranial swelling. Therefore, intracranial pressure monitoring or initiating mannitol, which is used to decrease intracranial edema, is not necessary.

Transcranial Doppler ultrasonography is useful for monitoring patients at risk for vasospasm after subarachnoid hemorrhage. It has not been found to be beneficial in the management of patients with encephalitis and would not be indicated in this patient.