Subacute sclerosing leukoencephalitis

Subacute sclerosing leukoencephalitis, more commonly known as subacute sclerosing panencephalitis (SSPE), is a rare, progressive, and ultimately fatal neurological disorder caused by a persistent infection of the central nervous system with a defective form of the measles virus. The disease typically develops years after an initial measles infection, often occurring when measles was contracted in early childhood (particularly before age 2). SSPE primarily affects the brain, causing widespread inflammation and demyelination of white matter as well as neuronal damage in gray matter, leading to progressive neurological deterioration. The disease typically progresses through four clinical stages. Stage I is characterized by subtle behavioral and cognitive changes, including personality changes, declining school performance, and irritability. Stage II involves the hallmark feature of myoclonic jerks (sudden, involuntary muscle spasms), along with further cognitive decline, seizures, and visual disturbances. Stage III is marked by increasing rigidity, spasticity, autonomic dysfunction, and progressive loss of motor and cognitive function, often leading to a decorticate or decerebrate state. Stage IV involves a vegetative state with loss of cortical function, eventually leading to death, typically within 1 to 3 years of symptom onset, though some patients may survive longer. Diagnosis is supported by characteristic electroencephalographic (EEG) findings (periodic high-amplitude slow-wave complexes), elevated measles antibody titers in cerebrospinal fluid, and typical MRI findings showing white matter lesions. There is no cure for SSPE. Treatment is largely supportive, though some antiviral agents such as isoprinosine (inosiplex) and intrathecal interferon-alpha have been used with limited success in slowing disease progression in some patients. The most effective strategy against SSPE is prevention through measles vaccination, which has dramatically reduced the incidence of this devastating condition in countries with high vaccination coverage.

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