Subacute sclerosing encephalitis (SSPE) and craniopharyngioma.
At the second hospitalization, elevated anti- measles antibody titers were detected (1:16 in CSF and 1:256 in the blood).
Subacute sclerosing panencephalitis (SSPE) is a chronic neuroinfection caused by a mutant measles virus (1, 3) that usually occurs in children. The clinical differential diagnosis of SSPE includes Schilder sclerosis, leukodystrophies, progressive paralysis, atypical forms of multiple sclerosis and variant CJD (1, 3, 6). Diagnosis is usually based upon a specific presentation with four stages, EEG with periodic stereotyped high voltage discharges, and elevated titers of anti-measles antibodies in the CSF and blood (3, 4, 7, 9). Stage I of disease is characterized by behavioral changes and cognitive decline. The visual problems and myoclonic jerks are typical for stage II, and stage III symptoms include dystonias, choreoathetosis and spasticity. In stage IV the symptoms progress to autonomic disturbances, coma and vegetative state (6, 9).
Histopathologically, SSPE is an encephalitis with prominent demyelination with variable topography and duration of lesions (1, 5). The occipital lobes are usually the initial location of the changes, and along with the chorioretinitis (which usually accompanies the presentation) are the main causes of visual symptoms (5, 6, 9). During the course of disease the process spreads into contiguous areas, including the basal ganglia and sometimes the spinal cord (5, 7). The perivascular and parenchymal inflammatory infiltrates are composed of lymphocytes, macrophages and activated microglia. Further characteristic and diagnostic findings are intranuclear Cowdry type A inclusions, which can be absent in longstanding cases (2, 4, 5, 8). Depending on duration of the process the active inflammation and/ or chronic destructive- reparative changes can be seen as diffuse demyelination, intense fibrillary gliosis, neuronal loss and brain atrophy. In some chronic cases Alzheimer- type changes are encountered (1, 4, 8).
Our patient had an unusual clinical picture with a prolonged period of stages I/ II and a fulminant course in the last few weeks of disease. The neuroimaging showed the evolution of the process which corresponded to some clinical symptoms and timing and topography of neuropathological changes. Lesions from the initial MRI correlated with Balint's syndrome, which is associated with bilateral posterior parietal and occipital damage (10). Histologically these areas showed inactive demyelinization, astrogliosis and severe cortical atrophy. In the temporal regions that actively changed in the second MRI there was inflammation along with chronic reparative gliosis and neuronal loss. The T2- hyperintense frontal areas in the last neuroimaging showed active demyelinating inflammation.
Neuropathological differential diagnosis of SSPE includes other types of viral encephalitides, as well as demyelinating diseases and neurometabolic disorders (4, 5, 8). The clue for the diagnosis is confirmation of the presence of the measles virus nucleocapsids within the inclusions with immunohistochemical, molecular or ultrastructural methods (2, 8, 10). In our case electron microscopy disclosed Paramyxovirus nucleocapsids, both in neuronal and oligodendroglial nuclei. Although SSPE is usually seen in children and young adults, this case demonstrates that SSPE should still be considered in the neurological and neuropathological differential diagnoses even in adult patients. Furthermore this is a first reported case of SSPE coexisting with a brain tumor (craniopharyngioma).
Contributed by Ewa Izycka-Swieszewska, Malgorzata Swierkocka- Miastkowska, Edyta Szurowska, Eliza Lewandowska, Teresa Wierzba-Bobrowicz, Krzysztof Jodzio