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Subacute sclerosing panencephalitis (SSPE) is a progressive, fatal neurodegenerative disorder caused by a persistent defective measles virus infection of the CNS, usually manifesting years after the initial measles illness. It predominantly affects children and young adults.

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https://www.youtube.com/watch?v=2DHOQLy3QKI

Etiopathogenesis

• Causative agent: Mutated measles virus that persists in neurons and oligodendrocytes.
• Latency period: Typically 6–8 years after acute measles infection (can range from 2 to 15 years).

Mechanism:

• Virus persists due to mutations in the viral matrix (M) protein → defective viral budding/clearance.
• Leads to chronic CNS infection, demyelination, gliosis, and neuronal loss.
• Risk factors: Early measles infection (<2 years age), absence of vaccination, immunosuppression.

![Pathogenesis of subacute sclerosing panencephalitis.

Mubbashir Z, Tharwani ZH, Kambar T, et al. Subacute sclerosing panencephalitis: Impact on public health, current insights, and future perspectives. Brain and Behavior. 2025;15(2). doi:10.1002/brb3.70292](attachment:4fd7d553-acc3-4af0-8ef0-65276f8096a3:image.png)

Pathogenesis of subacute sclerosing panencephalitis.

Mubbashir Z, Tharwani ZH, Kambar T, et al. Subacute sclerosing panencephalitis: Impact on public health, current insights, and future perspectives. Brain and Behavior. 2025;15(2). doi:10.1002/brb3.70292

Clinical Features

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Subacute sclerosing panencephalitis is a progressive, fatal neurodegenerative disorder due to persistent measles virus infection, presenting years after measles with behavioral changes, cognitive decline, myoclonus, seizures, and progressive dementia.

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Classically described in four stages of progressive neurological deterioration:

• Other features: Visual disturbances (chorioretinitis, optic atrophy), pyramidal signs, autonomic dysfunction.
• Course: Subacute (months–years), relentlessly progressive.

Diagnostic Criteria