• Gradual onset of behavioral changes
• School problems
• Bizarre behavior
• Myoclonic jerking (quick muscle jerking or spasms)
• Seizures
• Dementia (loss of cognitive, emotional, and social abilities)
• Unsteady gait
• Coma
• Patients may be rigid or flaccid, with weakness on both legs

There may be a history of measles in an unvaccinated child. Physical examination may show signs of optic nerve damage, damage to the retina (the part of the eye that perceives light and looks red when a photograph is taken with flash), poor motor cordination tests, and muscle twitching.

Tests:

• Electro-encephalogram (EEG): is a test of the electrical activity of the brain, which may show a wave pattern which is typical of SSPE
• Brain MRI, which provides high-quality pictures of the brain
• Serum antibody titer (concentration of the antibody), measles (rubeola) shows elevated titer to measles virus
• Spinal tap for analysis of the protein (immunoelectrophoresis) in the collected fluid
• Anti-measles virus antibodies