Subacute Sclerosing Panencephalitis (SSPE)
Background Neuroimaging Gross Pathology Histopathology & Immunohistochemistry
Differential Diagnosis Reference
BACKGROUND AND CLINICAL INFORMATION:
Head
Incidence:
The most common form of chronic encephalitides.
Pathogenesis:
Due
to reactivation of measles virus years after the initial attack. SSPE
preferentially occurs following measles during the first two years of life;
history of measles exposure a few weeks to up to six monthns before onset of
symptoms.
Immune
status: Most of the cases are seen in infants with cell mediated
immunodeficiency. Can also be seen
in immunosuppressed adults.
Course
of disease: The
course is progressive and has uncontrollable generalized seizures, epilepsia
partialis continua, progressive mental deterioriation and other neurological
abnormalities. Patients die in a few weeks to a few months.
CSF: High titer of measle antibody in serum and CSF. Oligoclonal bands may be seen.
Anatomical
distribution of lesions: The viral antigens are widely distributed in the
brain stem, basal ganglia, cerebral gray and white matter, but not cerebellum.
HISTOPATHOLOGY AND IMMUNOHISTOCHEMISTRY:
Head
General:
The
pathological findings correlate to some extent with the length of survival time
of the patient.
Inflammatory infiltration and inclusion:
Mild
plasmolymphocytic infiltration may be present in the cortex and meningitis;
microglial nodules and perivascular cuffing are not prominent features.
The
cortex is infiltrated by macrophages; a few neurons remain.
Intranuclear
inclusion bodies in oligodendroglial cells and neurons in about 20% of
cases; cytoplasmic inclusions may be seen in neurons.
Immunostaining
is useful in making diagnosis.
White
matter changes: Abnormalities in the white matter include mild perivascular
cuffing with lymphocytes, characteristically with numerous plasma cells, with
hypertrophied astrocytes, and/or gliosis and myelin destruction.