ENCEPHALITIS
The disease features: epidemic, tick-borne (spring-summer), Japanese and other types of encephalitis are primary infectious cerebral diseases. They manifest in the form of complications in case of systemic infections (e.g., measles, epidemic parotiditis, etc.).
Epidemic Encephalitis (Economo?s Encephalitis, Lethargic Encephalitis)
Economo described it in 1917 in connection with an epidemic. Economo's encephalitis is an infectious viral disease that is transmitted by droplets. Due to its contagiousness, the disease can take the form of an epidemic. Epidemic encephalitis has acute and chronic stages, between which it is possible a lucid interval or various residual disorders. Less often, the acute stage turns into chronic one, or the disease manifests itself only in the symptoms which are inherent to its chronic stage.
Clinical Picture of Epidemic Encephalitis
Acute Stage
Sudden onset of the disease is typical; sometimes, symptoms appear after a short time interval of prodrome. The most common disorder at the acute stage is pathological somnolence (lethargy). In overwhelming majority cases, it is lethargy that is a start of epidemic encephalitis. Nevertheless, it appears more often after delirium or hyperkinetic disorders. Patients sleep in various poses by day and by night, although they can be awakened to eat. From time
to time, due to increased intracranial pressure, obtundation can begin at the initial stage of the disease.
In many cases, delirious disorders begin even before the development of neurological symptoms (pareses of the oculomotor, abducent nerves, ptosis, and diplopia). Delirium is the most common form of acute exogenous psychosis for epidemic encephalitis. In such delirium, visual hallucinations can be moving, frightening, oneroid or simple (vision of fog, lightning or light). Auditory hallucinations are simple and not developed (music, chime, knocking, shots). Delirium states are combined with hyperkinesis phenomena. At the acute stage of epidemic encephalitis, psychomotor agitation often is like motor psychoses of a hyperkinetic nature. The onset of delusional disorders with the phenomena of catesthesia is much less common.