To Determine Diagnosis
- Consider need for CT prior to lumbar puncture:
- Perform to exclude mass lesion if altered consciousness, focal signs, papilledema, a recent seizure or is immunocompromised
- Do not delay treatment for CT – take blood cultures and commence antibiotics before scanning
- Lumbar puncture & CSF examination (if mass lesion excluded):
- Opening pressure
- Glucose, protein, lactate
- Cell count
- Gram stain
- Bacterial culture
- Pneumococcal and meningococcal PCR
- Viral PCR (enteroviruses, herpes simplex viruses type 1 and 2 (HSV-1 and HSV-2) and varicella zoster virus (VZV)
- Blood investigations:
- Blood cultures
- Pneumococcal and meningococcal PCR
- Glucose
- Lactate
- Procalcitonin
- Full blood count, urea, creatinine, electrolytes, liver function tests and clotting screen
- Additional investigations to determine aetiology:
- Throat swab for meningococcal culture
- Stool and/or throat swabs should be tested for enterovirus by PCR
- Selected investigations to detect source of infection:
- Chest X-ray – pneumonia
- Skull X-ray – fracture
- Sinus X-ray – sinusitis
- Petrous views – mastoiditis
To Assess for Complications
- Assess serum electrolytes (high frequency of SIADH)