If suspect temporal arteritis → ESR
If suspect meningitis → CSF studies
Cannot use CBC to rule-out meningitis
Add India Ink, cryptococcal antigen if suspect AIDS-related infection
If suspect CO poisoning → carboxyhemoglobin level
If concern for ICH → non-contrast CT Brain ± Lumbar puncture
Cannot use CBC to rule-out meningitis
Add India Ink, cryptococcal antigen if suspect AIDS-related infection
Consider non-contrast head CT in patients with:
Thunderclap<unk> 
Worst<unk>  of life
Different<unk>  from usual
Meningeal signs<unk>  + intractable vomiting
New-onset<unk>  in patients with:
Age > 50yrs
Malignancy
HIV
Neurological deficits (other than migraine with aura)
Consider CXR
50% of patients with pneumococcal meningitis<unk> ve evidence of pneumonia on CXR
Thunderclap<unk> 
Worst<unk>  of life
Different<unk>  from usual
Meningeal signs<unk>  + intractable vomiting
New-onset<unk>  in patients with:
Age > 50yrs
Malignancy
HIV
Neurological deficits (other than migraine with aura)
Age > 50yrs
Malignancy
HIV
Neurological deficits (other than migraine with aura)
50% of patients with pneumococcal meningitis<unk> ve evidence of pneumonia on CXR
Headache
Migraine headache
Tinnitus
Tension headache
Dizziness
Cluster headache
Sore throat
Meningitis/encephalitis