What is Lethargic Encephalitis in Children?
Lethargic encephalitis is also known as Economo encephalitis – named after a Viennese professor who studied the epidemic outbreak of the disease in France at the beginning of the 20th century. Lethargic encephalitis is an infectious viral disease that manifests itself in sleep disorders, oculomotor symptoms, has a long course, and often leads to parkinsonism.
Epidemiology
Sick people and healthy virus carriers transmit the infection to healthy people. The virus in them is concentrated in the secretion of the nasopharynx. How long the patient is able to infect others is not known exactly. Some researchers suggest that he poses the greatest threat during the incubation period and in the early days of the onset of the disease. There is also a scientific opinion that a person infected with a virus poses a danger to others for 2-3 years. Actively spread the disease in adults and children with erased forms.
The main route of transmission is airborne. This is proved recently by the raging major epidemics of lethargic encephalitis. The second transmission route is transplacental (from mother to fetus). In the scientific literature cases of infection of newborns from mothers in the body of which there was an infection of lethargic encephalitis were recorded.
Most diseases are erased or subclinical. Children under 12 months of age become ill in rare cases. The disease is inherent in seasonality. During the winter months, the maximum incidence rate in society is observed, especially in large cities.
Causes of Lethargic Encephalitis in Children
The causative agent of the disease is believed to be the virus. But until today, attempts to isolate it have not yielded results.
Pathogenesis during Lethargic Encephalitis in Children
Infection, as already noted, occurs by airborne droplets. The virus “clings” to the mucous membranes and enters the bloodstream, then into the central nervous system. The possibility of perineural movement of the virus to the central nervous system has not been established. The accumulation of the virus occurs mainly in the nerve cells of the gray matter of the brain. Presumably after the accumulation of the virus in the nerve cells, repeated viremia occurs, which leads to the manifestation of symptoms. Until now, mechanisms for the transition of infection into a chronic form have not been established. Crucial knowledge in this process is played by the weakness of the immune responses to the virus.
The maximum morphological changes concern the gray matter of the brain. Diapedetic hemorrhages, edema and hyperemia of the brain substance are detected, in some cases – thrombi of small vessels. Microscopic studies show perivascular infiltrates, degenerative changes in neurons up to their complete death, proliferation of neuroglia. Morphological changes are also found in the area of the aqueduct of the brain, the hypothalamus and subcortical nodes. In the chronic course of the disease, extensive glial scars are detected.
Symptoms of Lethargic Encephalitis in Children
The exact duration of the incubation period is still not known exactly. It is believed that it is from 4 to 15 days, but can last several months. The disease has an acute onset, body temperature rises, headaches, chills, nausea, and even vomiting begin.
In frequent cases, cough, runny nose, and sore throat are manifested. The mucous membrane of the pharynx with redness (hyperemia), there is a slight swelling. A striking sign of the disease is an early occurring sleep disorder. Drowsiness in a sick person occurs during the day, and insomnia haunts a person at night. Irresistible drowsiness may resemble a coma, but with lethargy, a sick child after waking up is well oriented in space.
An important symptom of lethargic encephalitis in children is oculomotor disorders associated with damage to the nuclei of III (oculomotor) and IV (block) pairs of cranial nerves. Because of this, there is a violation of convergence, paralysis of accommodation, double vision, lethargy or loss of pupillary reactions. With these processes, the face of a sick child becomes like a mask, facial expressions become scarce. There is a likelihood of vestibular disorders. Among the symptoms, instability of gait, dizziness, hypersalivation and sweating are also noted. Hypersalivation means an increase in the amount of saliva secreted.
The defeat of the extrapyramidal system leads to a hyperkinetic form of lethargic encephalitis. Outwardly, this is manifested by involuntary tics of the muscles of the face, head and neck.
With common hyperkinesis, the abdominal muscles and diaphragm are also affected, this leads to hiccups. Also common hyperkinesis threatens with torsion dystonia – body turns around the axis due to damage to the upper extremities of the body.
A blood test shows neutrophilic leukocytosis in the peripheral blood and increased ESR. Cerebrospinal fluid is transparent, intracerebral pressure is slightly increased.
Cases with lethargic and oculomotor disorders are designated as typical. Atypical forms of lethargic encephalitis:
- ticose (accompanied by involuntary twitching of individual muscle groups, mainly the face and neck);
- erased (there are no distinct sleep disturbances with intermittent, transient disorders of the oculomotor functions);
- vestibular (vestibular disorders predominate).
Subclinical forms of the disease are common – when typical symptoms do not occur.
The course and forecast
The course of lethargic encephalitis in children is acute and chronic. The acute course is characterized by the persistence of symptoms for 2-3 weeks with recovery within the 2nd month of illness. The chronic form is formed in 25-50% of patients. In such cases, after recovery, a lull occurs (without symptoms) for several months or even years. But in these periods, the patient may complain of headaches, drowsiness, increased fatigue and irritability. As a result, parkinsonism develops.
Parkinsonism is accompanied by a gradual mental disorder, a weakening of memory, activity and emotional associativity. As a result, intelligence decreases. In chronic forms, autonomic disorders occur, accompanied by an increase in the function of the sebaceous glands, profuse salivation and increased sweating.
The disease tends to worsen periodically. Adverse outcomes are frequent. This course of the disease is mostly affected by older children. During epidemics, the percentage of deaths is from 25 to 50%. The formation of parkinsonism often leads precisely to death. In recent years, the disease occurs in the form of sporadic cases and proceeds much easier, mortality decreased. Transition to a chronic form has also become a rarity.
Infants often suffer from the atypical form of lethargic encephalitis. Signs of drowsiness are not observed, and there are no oculomotor disorders. Symptoms are manifested as a runny nose, cough, polymorphic phenomena, rashes, gastrointestinal upset, cramps. A favorable course is observed in young children.
Diagnosis of Lethargic Encephalitis in Children
Lethargic encephalitis is diagnosed on the basis of the appearance of drowsiness in the child, vestibular oculomotor and ticose disorders. There are currently no laboratory diagnostic methods.
Treatment of Lethargic Encephalitis in Children
For the treatment of lethargic encephalitis, symptomatic and pathogenetic therapy is used, as with other encephalitis. Glucocorticosteroids are indicated in the acute period of the disease. In the chronic stage of Parkinson’s disease, doctors prescribe medications to reduce muscle tone, for example, cyclodol, norakin, amedin, tropacin, atropine, etc. Also, with parkinsonism, drugs that reduce stiffness (midcalm, levodopa, etc.) are indicated.
The patient is prescribed B vitamins, spa and physiotherapeutic treatment.
Prevention of Lethargic Encephalitis in Children
Preventive measures are not developed. Patients are hospitalized without fail. Strict isolation is necessary until the acute clinical manifestation of the disease disappears.