Joel A. VILENSKY¹, Christopher G. GOETZ² and Sid GILMAN^3
1Indiana University School of Medicine, Fort Wayne, Indiana, USA.  vilensk AT ipfw.edu
²Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois, USA.  christopher_goetz AT rush.edu
³Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA.  sgilman AT umich.edu

Encephalitis lethargica (EL) was a highly polymorphic neurological epidemic disease that occurred primarily from 1916 to 1925 and killed as many as 500,000 people worldwide. Although initial reports of the disorder focused upon extreme lethargy, later reports emphasized the highly variable nature of its signs and symptoms and that the disease often presented with a movement disorder. The most significant sequela of EL, postencephalitic parkinsonism (PEP), was characterized by a mixed movement disorder, including parkinsonism with festination, bradykinesia and rigidity, but also a variety of dystonic, tremorous, catatonic and myoclonic movements. We have collected a series of largely forgotten films from the US, England and Germany that depict the polymorphic manifestations of EL and PEP, and edited them into four video sequences:

1. Movement disorders of the head and neck: oculogyric crises, jaw and tongue tremors, open-mouth postures (convulsive yawning), and retrocollic (opisthotonic) postures.
2. Body posture and walking: shuffling gait, inability to maintain upright posture, stiff gait, stooped gait, and lack of associated upper limb movements while walking.
3. Festination and balance: forward and backward festination, and inability to maintain balance when pushed.
4. Body rigidity and other unusual movements: head and body tremors, myoclonus, catatonia, and limb rigidity.

Because no diagnostic test was developed for EL, clinical recognition of the typical features of the disorder was the only in vivo means to identify the condition during the epidemic period. Recently (2003), 20 new cases of EL were identified in England. Our films help determine whether these recent patients resemble the classic cases of epidemic EL. The ability to diagnose EL accurately may become important if the expected bird-flu epidemic does become manifest because EL was probably epidemiologically and/or etiologically associated with the 1918 bird-flu pandemic. These films provide objective documentation of epidemic EL and may help clinicians to be aware of the unusual constellation of signs that could herald another epidemic of this disease.

Pavia, Italy, 2006