Epidemic lethargic encephalitis Economome (encephalitis A): causes, symptoms, diagnosis, treatment
Last reviewed: 23.04.2024
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The epidemic lethargic encephalitis of Ekonomo (encephalitis A) was first recorded in 1915 in the troops near Verdun and was described in 1917 by the Viennese neurologist Ekonomo.
The disease in those years was in the form of epidemics that swept across many countries of the world. In subsequent years, all cases of the disease remained sporadic. At present, the disease in a typical form is almost never met.
The causes of the epidemic lethargic encephalitis
The causative agent of epidemic encephalitis has not been detected to date. The disease is not very contagious.
Symptoms of epidemic lethargic encephalitis
Clinically and pathomorphologically, epidemic encephalitis can be divided into 2 stages - acute and chronic. The acute stage is characterized by inflammatory symptoms. The chronic stage has a progressively degenerative character. Acute and chronic stages of epidemic encephalitis are separated by a period of time from several months to 5-10 years.
The classical form of epidemic encephalitis in the acute stage begins with an increase in body temperature to 38-39 ° C. There is a mild headache, vomiting, muscle pain, a sense of general weakness and other symptoms that accompany acute infectious diseases. Perhaps catarrh of the upper respiratory tract. The febrile period lasts an average of about 2 weeks. During this period, neurologic symptoms appear. In the foreground are pathognomonic for this disease of sleep disorders, expressed in pathological drowsiness. The patient can be awakened, but he immediately falls asleep again, and in any position and in a situation that is not suitable for sleep. Excessive, insuperable sleep can last for 2-3 weeks, and sometimes more. Somewhat less often there is pathological insomnia, when the patient can not fall asleep neither day nor night. Perhaps a perversion of a normal change of sleep and wakefulness. Insomnia often replaces the period of pathological drowsiness or precedes it.
The second characteristic feature of the acute stage is the defeat of large and small-cell nuclei of the oculomotor, less often, of the draining nerves. The oculomotor nerve is never fully involved in the process: the functions of the individual muscles innervated by this nerve are disturbed. Possible ptosis (one- or two-sided), diplopia, anisocoria, paralysis of the eye (often vertical), lack of pupillary response to convergence and accommodation in a living reaction to light (reverse syndrome of Argyl Robertson). Complaints about blurred vision caused by accommodation or diplopia are frequent.
Sleep disorders and oculomotor disorders form the classical form of epidemic encephalitis (hypersomal ophthalmoplegia), described by Economos. However, other neurological manifestations are possible in the acute stage. Somewhat less often than oculomotor disorders, vestibular disorders occur in the form of dizziness, accompanied by nausea and vomiting. In the neurological status, a horizontal and rotatory nystagmus is identified. Vestibular disorders appear due to damage to the nuclei of the vestibular nerve. Vegetative symptoms are often noted.
Extrapyramidal symptoms, characteristic of the chronic stage of epidemic encephalitis, are often noted in the acute stage. They can manifest hyperkinesis (choreoathetosis, myoclonia, athetosis, blepharospasm, seizure), somewhat less often - akinetic-rigid syndrome (akinesis, amyema, rigidity of muscles, a tendency to catatonia). The occurrence of thalamic, cerebellar and hydrocephalic syndromes, as well as hypothalamic disorders, is described. The acute stage can be accompanied by pronounced psychosensory disorders (changes in perception of the shape and color of surrounding objects, visual, olfactory, auditory hallucinations). In severe cases of epidemic encephalitis there are disorders of the frequency and rhythm of breathing, cardiovascular activity, myoclonia of the respiratory muscles, hyperthermia, impaired consciousness (coma). Possible fatal outcome due to cardiac and respiratory failure.
In modern conditions, epidemic encephalitis is atypical, mainly abortive, simulating acute respiratory infection. Against this background, there may be short-term sleep disorders (drowsiness or insomnia), episodes of diplopia, autonomic dysfunction, hyperkinesis (ticks in the muscles of the face and neck), mild pronounced transient oculomotor disorders. Isolate as an independent vestibular, narcoleptic, epileptiform form, epidemic hiccup (episodically occurring within a few days myoclonic spasm of the muscles of the diaphragm).
In the cerebrospinal fluid, in the majority of patients, pleocytosis (mainly lymphocytic, 40 cells per 1 μl), a slight increase in protein and glucose, is noted in most patients. In the blood, leucocytosis is found with an increase in the lymphocyte and eosinophil content, an increase in ESR. Generalized changes are revealed on the EEG; slow activity is expressed.
The course of epidemic lethargic encephalitis
The acute stage of epidemic encephalitis can last from 2-4 days to 4 months. Sometimes it ends with a complete recovery. A lethal outcome is recorded in 30% of cases. In 35-50% of patients, the acute stage becomes chronic. Often, the symptoms characteristic of the chronic stage, arise without a preceding clearly pronounced acute stage. The residual symptoms and syndromes after the acute stage of epidemic encephalitis carry headaches, persistent insomnia, a perversion of the rhythm of sleep, asthenoneurotic syndrome, depression, inadequacy of convergence, mild ptosis. Children often have hypothalamic disorders (endocrine-metabolic disorders), changes in the psyche and character, and decreased intelligence.
The main clinical manifestation of the chronic stage is parkinsonism syndrome. Poverty and slowness of movements, amy- mia, monotonous muffled low-expressive speech, pro-latero- and retropulse, pent-up attitude, loss of friendly movements, individualizing motility (aheyrokinez), paradoxical kinesias are characteristic. They note the loss of interest in the environment, the slowness of mental processes, importunity. In motor disorders, a significant role is played by disorders of tonus, usually diffusely elevated in plastic type (extrapyramidal rigidity) both in flexors and extensors, note the phenomenon of "cogwheel". Oligo- and bradykinesia are combined with a characteristic rhythmic hyperkinesis in the form of a small-scale tremor in the hands (as a "coin count"). Hyperkinesis in the chronic stage of epidemic encephalitis can also be manifested by blepharospasm, seizure of the eye (oculogic crises). Typical for Parkinson's secretory and vasomotor disorders (hypersalivation, skin grossness, hyperhidrosis).
Along with Parkinson's syndrome, endocrine disorders can develop in the form of adiposogenital dystrophy, infantilism, menstrual disorders, obesity or cachexia, hyperthyroidism, diabetes insipidus. Usually there are and are growing changes in the character, the emotional-volitional sphere. Especially pronounced changes in the psyche in children (increased eroticism, aggressiveness, antisocial behavior, painful pedantry, evening attacks of psychomotor agitation). Rarely in a chronic stage, epileptiform syndrome, seizures of pathological sleep (narcolepsy) and cataplexy are encountered.
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Diagnosis of epidemic lethargic encephalitis
Diagnosis of epidemic encephalitis in the acute stage is rather difficult. The basis for the diagnosis is various forms of sleep disturbance in combination with psychosensory disorders and symptoms of defeat of the nuclei of the oculomotor nerves. Especially important is the appearance of these symptoms against the background of increased body temperature and an "unclear" infectious disease.
It is necessary to differentiate the acute stage of epidemic encephalitis from serous meningitis. In recent years, with the help of an MRI of the brain, it is possible to confirm the diagnosis of epidemic encephalitis with pathological changes in the basal ganglia. However, a specific virus has not yet been identified.
Diagnosis of the chronic stage of epidemic encephalitis is less difficult. The diagnosis is based on a characteristic syndrome of parkinsonism, endocrine disorders of the central genesis, changes in the psyche. Important is the progressive nature of these disorders, especially in combination with some residual phenomena of the acute stage (ptosis, inadequacy of convergence and accommodation).
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What tests are needed?