Diffusion restriction in fulminant subacute sclerosing panencephalitis: Report of an unusual finding

Magnetic Resonance Imaging in Subacute Sclerosing Panencephalitis: Two Case Reports and Review of Literature

Subacute sclerosing panencephalitis (SSPE) is a slowly progressive neurodegenerative disease caused by the measles virus. This study investigated the magnetic resonance imaging (MRI) findings in SSPE by retrospective review of two cases diagnosed by typical periodic electroencephalographic (EEG) features, clinical symptoms and elevated measles antibody titre in cerebrospinal fluid (CSF). MRI revealed lesions of high signal intensity on T2-weighted images involving the periventricular or subcortical white matter in both the patients. Both these patients were given sodium valproate for seizures. However, the disease proved fatal in both these cases eventually.

Subacute sclerosing panencephalitis

Subacute sclerosing panencephalitis (SSPE) is a slowly progressive brain disorder caused by mutant measles virus. SSPE affects younger age groups. SSPE incidence is proportional to that of measles. High-income countries have seen substantial decline in SSPE incidence following universal vaccination against measles. SSPE virus differs from wild measles virus. Measles virus genome recovered from the autopsied brain tissues demonstrates clustered mutations in virus genome particularly in the M gene. These mutations destroy the structure and functioning of the encoded proteins. Complete infectious virus particle has rarely been recovered from the brain. Human neurons lack required receptor for entry of measles virus inside the neurons. Recent in vitro studies suggest that mutations in F protein confer hyperfusogenic properties to measles virus facilitating transneuronal viral spread. The inflammatory response in the brain leads to extensive tissue damage. Clinically, SSPE is characterized by florid panencephalitis. Clinically, SSPE is characterized by cognitive decline, periodic myoclonus, gait abnormalities, vision loss, and ultimately to a vegetative state. Chorioretinitis is a common ocular abnormality. Electroencephalography (EEG) shows characteristic periodic discharges. Neuroimaging demonstrates periventricular white matter signal abnormalities. In advanced stages, there is marked cerebral atrophy. Definitive diagnosis requires demonstration of elevated measles antibody titers in cerebrospinal fluid (CSF). Many drugs have been used to stabilize the course of the disease but without evidence from randomized clinical trials. Six percent of patients may experience prolonged spontaneous remission. Fusion inhibitor peptide may, in the future, be exploited to treat SSPE. A universal vaccination against measles is the only proven way to tackle this menace currently.