What EEG findings are characteristic of subacute sclerosing panencephalitis (SSPE)?

Updated: Oct 09, 2019
  • Author: Eli S Neiman, DO, FACN; Chief Editor: Selim R Benbadis, MD  more...
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Answer

Subacute sclerosing panencephalitis (SSPE) is a progressive neurodegenerative disorder caused by defective measles virus replication in the brain as a consequence of measles immunization.

The EEG may provide an important clue regarding SSPE and demonstrates bilaterally synchronous, high-amplitude spike or slow-wave bursts that often correlate with clinical myoclonus. As SSPE progresses, the background activity becomes suppressed, resulting in a burst-suppression pattern. Neuroimaging studies demonstrate nonspecific abnormalities or diffuse atrophy, although T2 prolongation can be detected by MRI symmetrically in the cerebral white matter or multifocally in the subcortical white matter or cortex.

Flaherty et al described a 17-year-old boy with SSPE discovered when he presented with confusion after a mild head injury. The EEG strongly suggested the diagnosis. Repeated CT scans of the head were normal. The boy had a 3-year history of decreased vision, associated with a focal pigmentary retinopathy. On assessment, the patient demonstrated visual agnosia and early dementia. MRI demonstrated symmetrical demyelination of the white matter, particularly in the occipital lobes. The typical EEG findings and the presence of measles antibodies in the CSF confirmed the diagnosis of SSPE. [57]

SSPE should be considered in young patients who have persisting cognitive dysfunction that is not proportional to the severity of the initial trauma. A focal pigmentary retinopathy, especially with macular involvement, should raise the possibility of SSPE, even if neurologic symptoms are absent initially. The longest interval (to date) between the visual symptoms and onset of neurological signs of SSPE was reported by the author.

Koppel et al reported on the relation of SSPE and HIV. At one time largely eliminated from the United States by nearly universal measles vaccination, SSPE has reemerged in HIV-infected children. Two children with SSPE were described. The first was HIV-positive and presented with seizures and encephalopathy at the age of 21 months. The second developed myoclonus and dementia at 4 years of age; she was not infected with HIV, but her mother had AIDS. MRI brain scans were nonspecific. EEG was characteristic of SSPE, showing high-voltage PSWCs and background slowing. Brain biopsy and high measles antibody titers in the CSF confirmed the diagnosis of SSPE. [58]


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