Dementia, Autoimmune/Paraneoplastic Evaluation, CSF (Sendout)

Useful For: Investigating new onset dementia and cognitive impairment plus 1 or more of the following accompaniments using cerebrospinal fluid specimens:

• Rapid onset and progression
• Fluctuating course
• Psychiatric accompaniments (psychosis, hallucinations)
• Movement disorder (myoclonus, tremor, dyskinesias
• Headache
• Autoimmune stigmata (personal history or family history or signs of diabetes mellitus, thyroid disorder, vitiligo, poliosis [premature graying], myasthenia gravis, rheumatoid arthritis, systemic lupus erythematosus)
• Smoking history (20+ pack years) or other cancer risk factors
• History of cancer
• Inflammatory cerebrospinal fluid
• Neuroimaging findings atypical for degenerative etiology

Refer to Autoimmune Encephalitis Testing Recommendations for additional ordering guidance.

Test Algorithm: Reflex testing may be performed at additional charge. Refer to the Mayo algorithm below for a full list of tests and potential reflex tests included in this panel.

• Autoimmune/Paraneoplastic Dementia Evaluation Algorithm-Spinal Fluid

Reference Values:

Note: Includes reference values for panel tests only.

Neuron-restricted patterns of IgG staining that do not fulfill criteria for ANNA-1, ANNA-2, ANNA-3, CRMP-5-IgG, PCA-2, or PCA-Tr may be reported as "unclassified anti-neuronal IgG." Complex patterns that include nonneuronal elements may be reported as "uninterpretable."

CRMP-5 Note: CRMP-5 titers lower than 1:2 are detectable by recombinant CRMP-5 Western blot analysis. CRMP-5 Western blot analysis will be done on request on stored spinal fluid (held 4 weeks). This supplemental testing is recommended in cases of chorea, vision loss, cranial neuropathy, and myelopathy.

Intepretation: Antibodies specific for neuronal, glial, or muscle proteins are valuable serological markers of autoimmune epilepsy and of a patient's immune response to cancer. These autoantibodies are not found in healthy subjects and are usually accompanied by subacute neurological symptoms and signs. It is not uncommon for more than 1 of the following autoantibodies to be detected in patients with autoimmune dementia:

• Plasma membrane antibodies (N-methyl-D-aspartate [NMDA] receptor; 2-amino-3-[5-methyl-3-oxo-1,2- oxazol-4-yl] propanoic acid [AMPA] receptor; gamma-amino butyric acid [GABA]-B receptor). These autoantibodies are all potential effectors of dysfunction.
• Neuronal nuclear autoantibody type 1 (ANNA-1) or type 3 (ANNA-3)
• Neuronal or muscle cytoplasmic antibodies (amphiphysin, Purkinje cell antibody-type 2 [PCA-2], collapsin response-mediator protein-5 neuronal [CRMP-5-IgG], or glutamic acid decarboxylase [GAD65] antibody).

Cautions:

Negative results do not exclude autoimmune dementia or cancer.

This evaluation does not detect Ma1 or Ma2 antibodies (also known as MaTa). Ma2 antibody has been described in patients with brainstem and limbic encephalitis in the context of testicular germ cell neoplasms. Scrotal ultrasound is advisable in men who present with unexplained subacute encephalitis.

Outside Laboratories: Refrigerate 4 mL (2 mL minimum) CSF in a sterile vial.

Stability: Refrigerated (Preferred): 28 days; Frozen: 28 days; Ambient: 72 hours.

Reject Due To: Gross hemolysis, lipemia, or icterus.

Refrigerate CSF in a sterile vial.

Login: SEND1-;REFRIG

• RSNDT1: MAYO
• RSTYP1: CSF
• RSTRQ1: ;Dementia Autoimmune Evaluation, CSF (Mayo Test DMC2)

Sendouts:

• Order Mayo test: DMC2.

Stability: Refrigerated (Preferred): 28 days; Frozen: 28 days; Ambient: 72 hours.

Reject Due To: Gross hemolysis, lipemia, or icterus.

CPTs: 86255x21, 86341x1

• Note: Includes panel tests only. Reflex testing may be added at additional charge.