A Rare Case of Subacute Sclerosing Panencephalitis in an Immunized Patient.

This study presents a case of subacute sclerosing panencephalitis (SSPE), a rare neurologic disorder characterized by brain inflammation, typically triggered by measles virus reactivation or an abnormal immune response to it. This case involves a five-year-old male child with persistent fever, declining motor function, excessive sleepiness, and myoclonic jerks. MRI indicated potential ischemic changes or encephalitis, while electroencephalography showed SSPE-consistent patterns. Further investigations confirmed SSPE, with elevated IgG levels in serum and cerebrospinal fluid (CSF) and positive measles IgG antibodies in CSF. Treatment included isoprinosine, lamivudine, and intrathecal interferon-alpha for symptom management and disease progression. Despite atypical SSPE features, subclinical measles infection was considered a probable cause. The patient showed partial improvement post-treatment and was discharged for follow-up. By reporting this case, we would like to emphasize clinical judgment, early detection of the symptoms, and lateral thinking to diagnose fatal conditions such as post-measles SSPE, even in fully immunized patients.