Patient with Suspected Meningitis Age > 56 days — Interpretation of CSF Results — Clinical Pathway: Emergency, Inpatient

Suspected Meningitis Age > 56 days Clinical Pathway — Emergency Department, Inpatient and ICU

Interpretation of CSF Results, Typical CSF Parameters

Normal CSF Values for Infants/Children > 56 Days

WBC 0-6 cells/µL1
Glucose 40-80 mg/dL
Protein 5-40 mg/dL

CSF Values and Bacterial Meningitis

CSF Findings Suggestive of Acute Bacterial Meningitis
  • Interpret findings with history, physical examination, and other labs in determining a patient’s likelihood of having bacterial meningitis.
    • Cloudy or purulent CSF fluid
    • Increased opening pressure (> 25 cm H20)
    • Positive CSF Gram stain2
    • Abnormal CSF WBC count (varies by age)
    • CSF neutrophils > 50%
    • Increased CSF protein > 100 mg/dL
    • Decreased CSF glucose (< 40% serum glucose)
Findings Suggestive of Low Risk for Bacterial Meningitis in Children > 2 Months of Age3
  • CSF Gram stain negative for organisms
  • CSF protein < 80 mg/dl
  • No history of seizure before or at the time of presentation
  • Peripheral absolute neutrophil count < 10,000 cells/mm3
  • CSF absolute neutrophil count < 1000 cells/mm3
  • Not ill-appearing, not immunocompromised, no VP shunt, no recent neurosurgery, no antibiotic pre-treatment, no petechiae or purpura

Interpreting Bloody CSF

Elevated RBCs or Bloody Tap
  • May be seen with traumatic LP or intracranial (subarachnoid or intraparenchymal) hemorrhage.
  • Because correction methods using RBC to WBC ratios have not been validated, it may be appropriate to begin empiric antibiotics when CSF pleocytosis is present

References

  1. Hematology Laboratory flags all CSF WBC count ≥ 6 cells/µL as abnormal. CSF normal values are taken from the textbook: JL McGuire and AM Greene: Central Nervous System Infections (Chapter 16). Pediatric Neurocritical Care. NS Abend and M Helfaer (eds.). Demos, New York, Page: 267-336, 2013.
  2. Infectious Diseases Diagnostics Laboratory will call the attending physician with all positive CSF Gram stains.
  3. Nigrovic et al. Clinical prediction rule for identifying children with cerebrospinal fluid pleocytosis at very low risk of bacterial meningitis. JAMA 2007; 297(1):52-60.

Typical CSF Parameters by Disease in an Immune Competent Child > 56 Days Old

Below are typical CSF findings by disease with references for healthy children and children with bacterial meningitis. These may assist clinical decision making; however, note there is much overlap. Thus for patients with possible bacterial meningitis, timely antibiotic administration is a priority.

References

  CSF WBC CSF protein CSF glucose Opening pressure
Healthy 0-6 cells/hpf 5-40 mg/dL ~0.6x serum 11.5-28
Bacterial meningitis ↑ to ↑↑↑ (PMN) ↑ ↓ Normal or ↑
PMN, polymorphonuclear cell

Alternative CNS Infections

  CSF WBC CSF protein CSF glucose Opening pressure
Viral meningoencephalitis (enterovirus, others) ↑ (L/M) ↑ Normal or only slightly ↓ Normal or ↑
Lyme meningitis ↑ to ↑↑↑ (L) ↑ Normal Normal or ↑
TB meningitis ↑ to ↑↑↑ (L) ↑↑↑ ↓ ↑
Parameningeal abscess or empyema Normal or ↑ (PMN) Normal to ↑ Normal Normal or ↑
L, lymphocyte; M, monocyte; PMN, polymorphonuclear cell

Other Diagnoses

  CSF WBC CSF protein CSF glucose Opening pressure
Aseptic meningitis due to medications (IVIg, Bactrim) ↑ Normal Normal Normal or ↑
Idiopathic intracranial hypertension/pseudotumor cerebri Normal Normal Normal ↑ to ↑↑↑
Other causes of intracranial hypertension (tumor) Normal or ↑ Normal or ↑ Normal ↑ to ↑↑↑
Kawasaki Disease Normal or ↑ Normal Normal Normal
L, lymphocyte; M, monocyte; PMN, polymorphonuclear cell