Background: Encephalitis lethargica (EL) is a CNS disorder that manifests with lethargy sleep cycle disturbances, extrapyramidal symptomatology, neuropsychiatric manifestations, ocular features and cardio-respiratory abnormalities. Although there have been no reported outbreaks of EL recently, a number of reports show that cases of EL are still encountered regularly. Against this background we conducted a study aiming to elucidate the clinical characteristics, describe laboratory/ neuroimaging findings (MRI, PET) and present treatment options and outcomes in sporadic EL.
Methods: Patients were diagnosed over a period of 3 years using proposed diagnostic criteria. Extensive laboratory and imaging tests were performed for exclusion of other causes. Anti-neuronal antibodies against human basal ganglia were detected with western immunoblotting and (18)F-FDG PET imaging was performed. Selected cases were videotaped.
Results: Our patients (M/F: 5/3) ranged from 2-28 years (mean 9.3 +/- 9.5). Encephalopathy, sleep disturbances and extrapyramidal symptoms were present in all cases. Laboratory investigations revealed CSF leukocytosis in 5/8 patients and anti-BG Ab in 4/7 patients. MRIs revealed structural abnormalities in 7/8 cases. (18)F-FDG PET showed basal ganglionic hypermetabolism in 4/7 patients. Treatment approaches included immunomodulating and symptomatic therapies. We report no mortality from EL in our series.
Conclusions: There seems to be little doubt that cases of EL still occur. Diagnosis may be based on clinical suspicion and laboratory/imaging tests may lead to early initiation of immunomodulating and supporting therapies. We suggest that in addition to anti-BG Abs FDG PET should be considered as a diagnostic tool for EL.