Is the presence of measles antibody in cerebrospinal fluid (CSF) specific for subacute sclerosing panencephalitis (SSPE)?

Measles Antibody in CSF is Highly Specific for SSPE Diagnosis

The presence of measles antibody in cerebrospinal fluid (CSF) is highly specific for the diagnosis of subacute sclerosing panencephalitis (SSPE) and serves as a key diagnostic marker for this condition. 1

Diagnostic Value of Measles Antibodies in CSF for SSPE

• Detection of intrathecal synthesis of measles-specific antibodies in CSF is a crucial diagnostic criterion for SSPE 1
• SSPE has a characteristic clinical presentation with insidious onset, subtle personality changes, declining intellectual performance progressing to mental deterioration, seizures, myoclonic jerks, motor signs, coma, and death 1
• The EEG in SSPE reveals well-defined periodic complexes with a 1:1 relationship with the myoclonic jerks, which is another distinctive feature 1

Specificity of Measles Antibody Testing in CSF

• Elevated CSF/serum measles antibody indices (CSQrel ≥ 1.5) are considered indicative of intrathecal measles antibody synthesis and diagnostic for SSPE 2
• Measles-specific IgM antibodies are typically higher in CSF than in serum in SSPE patients, reflecting local production in the central nervous system 3
• Oligoclonal measles virus-specific IgG antibodies can be isolated from CSF and brain extracts in patients with SSPE, supporting the concept of local synthesis in the nervous system 4, 5

Clinical Context and Differential Diagnosis

• Measles can cause three separate encephalitic illnesses:

  1. Acute encephalitis or acute disseminated encephalomyelitis associated with acute infection
  2. Subacute encephalopathy in immunocompromised patients (around six months after primary infection)
  3. SSPE in immunologically normal individuals (occurring several years after primary infection) 1

• The detection of measles antibodies in CSF should be interpreted in the context of:

  • Clinical presentation (progressive neurological disorder with cognitive decline and myoclonus)
  • EEG findings (periodic complexes)
  • History of measles infection or vaccination status 1, 2

Diagnostic Algorithm for SSPE

1. Test for measles antibodies in simultaneously obtained serum and CSF samples 2
2. Calculate the CSF/serum antibody index (values ≥1.5 indicate intrathecal synthesis) 2
3. Look for oligoclonal bands in CSF with immunoblotting against measles virus proteins 1
4. Consider PCR testing of CSF for measles virus RNA (though antibody testing is often more reliable for SSPE) 1

Important Caveats and Considerations

• In rare cases, patients with SSPE may have absent antimeasles antibody in CSF when measured by conventional immunoassay techniques, requiring more sensitive methods like radioimmunoprecipitation 6
• The MRZ reaction (measles, rubella, and zoster virus intrathecal antibody synthesis) can be present in multiple sclerosis (MS), potentially causing confusion, but the pattern differs from the isolated strong measles response in SSPE 1
• Some MS patients may have measles antibodies in CSF, but typically only part of the oligoclonal IgG is associated with measles antibody activity, whereas in SSPE most or all oligoclonal IgG proteins carry measles antibody activities 4

Prevention and Management Implications

• Effective measles vaccination is the only way to prevent measles infection and subsequent SSPE development 2
• Intrathecal ribavirin has been used for treatment of SSPE, though with limited success 1
• The period between measles infection and SSPE development can range from 4.5 to 15 years, highlighting the importance of vaccination 2