Encephalitis lethargica is a condition marked by a high fever, headache, double vision, delayed physical and mental responsiveness, and lethargy. In acute cases, people may develop a coma. In addition to psychosis, patients may have psychotic behavior, aberrant eye movements, upper body weakness, muscular aches, tremors, and neck rigidity. The unknown is the cause of encephalitis lethargica. From 1917 through 1928, an epidemic of encephalitis lethargica swept the globe, but there has been no recurrence of the outbreak since. Postencephalitic Parkinson’s disease can occur after an episode of encephalitis, occasionally up to a year later.
History
Since the late 16th century, numerous European nations have documented disease epidemics that appear to have been comparable to EL. The neurologist Constantin Von Economo coined the term encephalitis lethargica in 1916, at an early stage of the epidemic that occurred during and after World War I.
Estimates of the number of cases have varied widely due to the difficulty of diagnosis and the lack of statistical records in many countries. Although descriptions vary, it appears that previously males were more susceptible. The vast majority of instances (up to 30/40 years old) involve younger individuals. There were few reliable data about race and ethnicity, although some accounts stated black mortality was lower.
EL was viewed as a phenomenon of the past for many years. In recent years, there has been renewed interest in the condition’s cause and connections with post-encephalitic Parkinson’s disease. The neurologist Oliver Sacks characterized the ‘awakenings’ of historical patients, but newer publications have detailed contemporary cases and defined the condition in contemporary terms.
Approximately one-third of those infected perished, according to contemporary estimates. Patients who survived EL frequently acquired a form of Parkinsonism known as post-encephalitic Parkinson’s disease, which is associated with severe neurological impairment.
Symptoms
Encephalitis lethargica is marked by a high fever, sore throat, headache, double vision, a delay in physical and mental reaction, sleep inversion, catatonia, and lethargy. Patients may enter a coma-like state in acute situations (akinetic mutism). In addition, patients may have psychosis and irregular eye movements, parkinsonism, upper body weakness, muscle aches, tremors, and neck rigidity, as well as alterations in behavior, such as psychosis.
Postencephalitic After a case of encephalitis, Parkinson’s disease can sometimes occur up to a year later. A number of diagnostic criteria for encephalitis lethargica have been offered. One widely recognized definition includes an acute or subacute encephalitic illness in which all other known causes of encephalitis have been ruled out. A more recent diagnostic criterion states that the diagnosis of encephalitis lethargica “may be considered if the patient’s condition cannot be attributed to any other known neurological condition and they exhibit the following symptoms: influenza-like symptoms; hypersomnolence; walkability; ophthalmoplegia; and psychiatric changes.
Treatment
Modern treatments for encephalitis lethargica include immunomodulatory medications and treatments designed to alleviate particular symptoms.
Until now, there is little evidence of a consistently effective treatment for the first stages, but steroid-treated individuals have demonstrated improvement. Similar brain damage to that of Parkinson’s disease is observed as the disease advances.
Thus, treatment is symptomatic. L-DOPA (Levodopa) and other anti-Parkinson medications frequently have remarkable effects; however, the majority of L-DOPA recipients see only temporary relief.
Prognosis
The result may vary. Some individuals may achieve a full recovery, while others may, sadly, pass away, while others may continue to have Parkinsonian-like symptoms. Von Economo observed, “These people appear to be suffering from a severe form of secondary dementia.” Although emotions are barely discernible on the face, they are mentally sound.
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