Both viral encephalitis and viral meningitis are acute intracranial inflammatory diseases caused by multiple viruses. Different types of disease develop due to differences in pathogenic properties and host response processes. If the inflammatory process is primarily in the meninges, the clinical focus is on viral meningitis. When the brain parenchyma is mainly involved, viral encephalitis is the clinical characteristic.
I. Clinical manifestations
1, viral meningitis Acute onset, or preceded by episodic or antecedent infectious diseases. The main manifestations are fever, nausea, vomiting, weakness, and drowsiness. Older children may complain of headache, while infants are irritable and easily agitated. There is usually little severe disturbance of consciousness and convulsions. There may be signs of meningeal irritation such as cervical tonicity. However, there are no restrictive neurological signs. The duration of the disease is mostly 1 to 2 weeks.
Viral encephalitis has an acute onset, but its clinical manifestations vary depending on the location, extent and severity of the major pathological changes in the brain parenchyma. The duration of viral encephalitis is mostly 2 to 3 weeks.
(1) Most children present with fever, recurrent convulsive episodes, varying degrees of impaired consciousness and increased cranial pressure based on diffuse brain lesions. Most of the convulsions are total, but there can be focal seizures, and in severe cases, there is a continuous state of convulsions. The child may be drowsy, lethargic, comatose, in a deep coma, or even in a decorticated state with varying degrees of altered consciousness. If there is irregular respiratory rhythm or unequal pupil size, intracranial hypertension with brain herniation should be considered. Some children also have hemiparesis or limb paralysis.
(2) In some children, the lesions mainly involve the frontal cortical motor area, and the main clinical manifestation is recurrent convulsive seizures with or without fever. Most of them are total or focal tonic-clonic or clonic seizures, and a few of them are myoclonic or tonic seizures. All may present with epileptic seizure continuity.
(3) If the brain lesion mainly involves the frontal lobe base and temporal lobe limbic system, the patient mainly presents with mental and emotional abnormalities, such as mania, hallucinations, aphasia, and disorientation, calculation and memory impairment. Fever is present with or without fever. A variety of viruses can cause these manifestations, but herpes simplex virus is the most severe. In this virus, inclusion bodies containing viral antigenic particles are easily found in the neuronal cells of encephalitis, which is sometimes referred to as acute inclusion body encephalitis, often combined with convulsions and coma, and has a high mortality rate.
Diagnosis
Laboratory tests.
1, Peripheral white blood cell count is normal or mildly elevated.
2, lumbar puncture is a necessary means of examination: cerebrospinal fluid examination Appearance colorless and transparent, pressure normal or slightly high, leukocytes mildly to moderately elevated, generally in the (25-250) × 106 / L. Within 48 h after the onset of neutrophilic polymorphonuclear leukocytes predominate, but quickly turn to mononuclear cells predominate. Protein is mildly increased, sugar is normal, and chloride may occasionally decrease. No bacterial findings on smear and culture.
3. Virological examination Some patients have positive cerebrospinal fluid virus culture and specific antibody test. Serum specific antibody titers in the recovery period are more than 4 times higher than those in the acute period and have diagnostic value. If the viral DNA is positive, the diagnosis can be confirmed.
Other auxiliary examinations.
1. Imaging examinations CT or MRI of the brain is usually not abnormal. In severe cases, MRI reveals high-signal lesions such as medial temporal lobe and hippocampus.
EEG is characterized by diffuse or limited abnormal slow-wave background activity, with a few accompanying spike waves and spike-slow integrated waves. Slow wave background activity can only indicate abnormal brain function, but cannot confirm the nature of viral infection. Some patients may also have normal EEG.
Treatment
There is no specific treatment for this disease. However, due to the self-limiting nature of the disease, proper supportive and symptomatic treatment during the acute phase is the key to ensuring a smooth recovery and reducing the mortality and disability rates.
The main treatment principles include.
1. Maintain water and electrolyte balance and reasonable nutrition supply. Give intravenous nutrients or human albumin (albumin) to those with poor nutritional status.
2. Control cerebral edema and intracranial hypertension.
3. Control convulsive seizures and severe mental behavior abnormalities. Severe impact on the patient’s ventilatory function requires monitoring and treatment in the neurological intensive care unit.
4.Anti-viral drugs . Acyclovir (acyclovir), 5-10mg/kg per dose, once every 8 hours. Or its derivative ganciclovir (propoxyphene), 5mg/kg every time, once every 12 hours. Both drugs need to be administered by intravenous drip for 10 to 14 days. It has the strongest effect mainly on herpes simplex virus, but also inhibits other viruses such as varicella-zoster virus, cytomegalovirus, and EBV.
In viral meningitis caused by coxsackie or echovirus, the hormone dexamethasone (flumethasone) is usually administered intravenously to control the inflammatory response at a dose of 15 mg/d in adults and less in children. Early application of mannitol and furosemide (tachyphylaxis) dehydrating agents in moderation can reduce the symptoms of cerebral edema. When it is difficult to exclude herpes simplex virus or varicella zoster virus infection, antiviral agents should be applied promptly. Patients with respiratory distress, swallowing disorder and convulsions should be treated with ventilator, nasal diet and medication.
IV. Prognosis
The prognosis of patients with enterovirus infection is generally benign and good; the prognosis of patients with herpes simplex virus, especially those with combined bleeding, is poor if medication is not used in a timely manner.