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AUTOIMMUNE ENCEPHALITIS PANEL-2, CSF
Immunity
Report in 192Hrs
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No Fasting Required
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CSF antibody panel for autoimmune encephalitis.
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AUTOIMMUNE ENCEPHALITIS PANEL-2 CSF
- Why is it done?
- Detects antibodies against neuronal and glial cell surface antigens in cerebrospinal fluid (CSF) to identify autoimmune-mediated encephalitis
- Screens for multiple antibody targets including NMDA receptor, AMPA receptor, GABA-B receptor, LGI1, CASPR2, DPPX, and other CNS antigens in the CSF compartment
- Indicated in patients presenting with unexplained subacute encephalitis characterized by confusion, altered mental status, seizures, movement disorders, or behavioral changes
- Helps differentiate autoimmune encephalitis from infectious or other neurological causes when CSF pleocytosis is present
- Typically performed early in the diagnostic workup when autoimmune encephalitis is suspected and imaging and infectious studies are inconclusive
- Essential for guiding immunotherapy initiation and determining prognosis in encephalitis patients
- Normal Range
- Negative Result: No antibodies detected against any of the tested antigens (NMDA-R, AMPA-R, GABA-B-R, LGI1, CASPR2, DPPX, and other CNS targets). This is the normal/expected finding.
- Positive Result: Detection of one or more autoantibodies in CSF. Presence of specific antibodies correlates with specific autoimmune encephalitis phenotypes and warrants clinical correlation.
- Units: Qualitative (Positive/Negative) or semi-quantitative titers (Index values, U/mL) depending on methodology used
- Borderline/Equivocal Results: May indicate weakly positive or uncertain antibody presence requiring repeat testing, serum correlation, or follow-up CSF sampling
- Interpretation Principle: CSF detection of antibodies is more specific for CNS involvement than serum antibodies. CSF positivity in the appropriate clinical context establishes autoimmune encephalitis diagnosis.
- Interpretation
- NMDA Receptor Antibody Positive: Indicates NMDA receptor encephalitis, most common in young females; presents with psychiatric symptoms, movement disorders, autonomic instability, seizures, and decreased consciousness
- AMPA Receptor Antibody Positive: Suggests rapidly progressive cognitive decline, seizures, and often associated with underlying malignancy; strong correlation with paraneoplastic syndrome
- GABA-B Receptor Antibody Positive: Associated with prominent seizures, behavioral changes, memory impairment; significant association with small-cell lung cancer and other malignancies
- LGI1 Antibody Positive: Presents with faciobrachial dystonic seizures, memory disturbance, and relatively favorable prognosis; typically seronegative for cancer
- CASPR2 Antibody Positive: Associated with Isaacs syndrome, neuromyotonia, and encephalitis; can present with seizures and autonomic dysfunction; lower malignancy association
- DPPX Antibody Positive: Results in severe tremor, hyperekplexia, ataxia, myoclonus, and behavioral changes; rapidly progressive course requiring aggressive immunotherapy
- Multiple Antibodies Positive: Rare finding; may suggest overlapping syndromes or secondary immune activation; requires careful clinical correlation and potential repeat testing
- Negative Panel with High Clinical Suspicion: Does not exclude autoimmune encephalitis; consider intracellular antibodies (anti-Hu, anti-Yo, anti-CV2), additional antibodies not in standard panel, or serum testing
- Factors Affecting Interpretation: Timing of CSF collection relative to symptom onset, immunotherapy initiation before testing, concurrent infection, renal function affecting antibody clearance, and blood-brain barrier integrity
- Associated Organs
- Primary Organ System: Central Nervous System (CNS) including brain, spinal cord, and meninges
- Brain Regions Involved: Hippocampus (memory dysfunction), limbic system (behavioral/psychiatric symptoms), motor cortex, basal ganglia (movement disorders), and brainstem
- Associated Autoimmune Encephalitis Diseases: NMDA receptor encephalitis, AMPA receptor encephalitis, GABA-B receptor encephalitis, LGI1-associated encephalitis, CASPR2-associated encephalitis, DPPX-associated encephalitis, and other CNS-specific autoimmune disorders
- Associated Malignancies: Small-cell lung cancer, ovarian teratoma (NMDA-R), breast cancer, melanoma, lymphoma, and other occult malignancies depending on antibody type
- Secondary Organ Involvement: Peripheral nervous system (neuromyotonia with CASPR2), autonomic nervous system dysfunction, and potential involvement of muscles and organs depending on antibody specificity
- Potential Complications: Status epilepticus, aspiration pneumonia from decreased consciousness, autonomic instability with cardiac arrhythmias, respiratory failure requiring mechanical ventilation, memory loss and cognitive impairment, movement disorders, permanent neurological disability if untreated
- Risk of Disease Progression: Early detection and treatment initiation are critical to prevent irreversible neuronal damage and improve long-term functional outcomes
- Follow-up Tests
- Serum Autoimmune Panel: Concurrent testing to check for antibodies in serum; CSF-restricted antibodies have higher specificity but serum positivity helps establish systemic involvement
- Extended Antibody Panel (Intracellular Antigens): Anti-Hu, anti-Yo, anti-CV2/CRMP5, anti-amphiphysin, anti-CRMP5 if initial panel negative but clinical suspicion remains high
- Neuroimaging (MRI Brain/Spine): To assess for evidence of inflammation, lesions, or structural abnormalities; repeated if clinical deterioration or new symptoms develop
- Electroencephalography (EEG): To evaluate seizure activity and identify characteristic patterns such as extreme delta brush or psychomotor seizures; serial EEGs to monitor treatment response
- Malignancy Screening: Comprehensive cancer screening including CT chest/abdomen/pelvis, mammography (females), pelvic ultrasound (NMDA-R cases), and age-appropriate malignancy workup based on antibody type
- Repeat CSF Analysis: If initial panel is negative but clinical suspicion remains, repeat lumbar puncture at 5-10 days may increase antibody detection rates
- CSF Studies (Basic Parameters): Cell count, differential, glucose, protein, lactate, and cultures to exclude infectious causes; oligoclonal bands and immunoglobulin index to assess intrathecal synthesis
- Brain Biopsy: Rarely needed but may be considered if diagnosis remains unclear after extensive workup and clinical deterioration requires definitive diagnosis
- Monitoring Frequency: Clinical examination at least weekly during acute phase; MRI/EEG at baseline, 4-6 weeks, and 3-6 months post-treatment; repeat CSF if clinical plateau or deterioration
- Long-term Follow-up: Neuropsychological testing at 6-12 months to assess cognitive recovery; neuro-oncology surveillance if malignancy detected; immunosuppressive regimen monitoring
- Fasting Required?
- Fasting Status: No fasting required. CSF is collected via lumbar puncture (spinal tap) procedure rather than blood draw, so fasting status is not relevant to sample collection.
- Pre-procedure Preparation: Patient may eat and drink normally before lumbar puncture unless otherwise instructed by physician. Patients should be well-hydrated prior to procedure.
- Medications to Avoid: Anticoagulants (warfarin, apixaban, rivaroxaban) should be held 3-5 days prior if possible; antiplatelet agents (aspirin, clopidogrel) hold 5-7 days; discuss with physician as risk-benefit varies by clinical context
- Other Special Instructions: Void bladder before procedure; lie flat for 1-2 hours post-procedure to reduce post-lumbar puncture headache; increase fluid intake after procedure; consider analgesics for post-procedure headache
- Procedural Requirements: Informed consent required; baseline coagulation studies (PT/INR, PTT) should be normal or corrected; CT brain or MRI recommended before LP if papilledema, focal deficits, or mass effect suspected
- Sample Handling: CSF must be processed quickly; refrigeration at 2-8°C if processing delayed; sample should not be frozen; tubes should be sterile and free of contaminants for optimal antibody detection
- Additional Blood Draw: Concurrent serum sample should be collected for comparison; blood can be drawn with standard precautions without fasting requirement
How our test process works!
