Encephalitis in children
What is encephalitis?
Encephalitis is the inflammation of the brain. It is most often caused by a virus either as a direct infection of the virus to the brain (acute viral encephalitis) or as an autoimmune process following a viral infection elsewhere in the body (post-infectious encephalitis or acute disseminated encephalomyelitis).
What viral infections cause encephalitis?
Most viral infections in childhood are able to cause encephalitis.
Encephalitis caused by Herpes simplex virus (HSV) 1 or 2 is recognized worldwide as the most frequent infectious encephalitis. HSV-1 usually causes cold sores or blisters around the mouth, and HSV-2 commonly causes sexually transmitted infection. Encephalitis as a result of HSV-1 may cause significant brain damage or death. Other herpes viruses that may cause encephalitis include the Epstein-Barr virus which causes infectious mononucleosis, Varicella-zoster virus (VZV) which causes chickenpox and shingles, and Cytomegalovirus (CMV) seen in persons with weak immune system.
Enteroviruses include the Poliovirus and the Coxsackie virus. They usually cause flu-like illness with eye inflammation and abdominal pain. Mosquitoborne arboviruses in the Philippines include Dengue and Japanese encephalitis viruses. Other viral causes include adenovirus, influenza virus and rabies.
Common childhood infections such as Measles, Mumps and German Measles, used to be fairly common causes of post-infectious encephalitis, are rare causes now because of the availability of vaccinations for these diseases.
When will you suspect that a child is having encephalitis?
The characteristics are fever, headache and altered mental status ( confused thinking, drowsiness, coma). Additional symptoms may be neck stiffness, vomiting, and convulsions. There may be a history of infection elsewhere in the body.
How is encephalitis diagnosed?
Brain imaging is often the first test if a patient’s history and symptoms suggest the possibility of encephalitis. The images may reveal swelling of the brain. Magnetic Resonance Imaging ( MRI) is preferred because detailed crosssectional and 3-D images of the brain are produced. Computerized tomography (CT) may also be an alternative imaging study.
Lumbar puncture is the examination of cerebrospinal fluid (CSF) to determine what infection is causing the encephalitis. The doctor inserts a needle into the lower back to extract the CSF fluid (the protective fluid that surrounds the brain and spinal column). Changes in this fluid can indicate infection and inflammation in the brain. It can be tested for PCR (polymerase chain reaction) or serology (antibody test) to specifically identify the virus. All patients with suspected encephalitis should have a CSF PCR test for HSV 1 and 2, VZV and enteroviruses, as this will identify 90 percent of cases due to known viral causes.
An Electroencephalogram (EEG) determines the slowing down of electrical activity of the brain by affixing electrodes to the scalp. Samples of blood, urine or throat swabs can also be tested for viruses or other infectious agents.
How do you treat persons with encephalitis?
Persons with encephalitis need urgent hospital admission. Prompt treatment with acyclovir through the vein to cover for Herpes simplex can be life-saving if started immediately. This can improve the outcome if given before coma develops. Acyclovir can also be given for encephalitis caused by chicken pox. Ganciclovir is the drug for CMV encephalitis. There is no specific treatment for other viral causes and the emphasis of treatment is supportive. This includes anticonvulsants and sedatives (to reduce agitation). Intensive care, including ventilation, may also be necessary in severe cases.
What is the importance of getting timely diagnosis and treatment?
Severe cases of encephalitis can be life-threatening. It is important to get a timely diagnosis and treatment because the course can be unpredictable. Being brought to a tertiary hospital with complete imaging studies, laboratory tests, intensive care and rehabilitation facilities is vital.
The ability to specifically identify the virus causing the encephalitis is available at St. Luke’s Medical Center’s Institute of Pathology or Research and Biotechnology Division. The CSF can be tested for PCR and serology of the following viruses: HSV 1 and 2, Dengue, Japanese Encephalitis, Chickenpox and CMV. Blood tests can also determine viruses such as Epstein Barr virus, Mumps, Measles and Rubella. Throat swab for Influenza is also available. Only very few hospitals in the country have this capability of determining specific viruses in the brain and blood.
Depending on the type and severity of complications, it may be necessary to receive additional therapy like: (1) Physical therapy to improve strength, flexibility, balance, motor coordination and mobility, (2) Occupational therapy to develop everyday skills and to use adaptive products that help with everyday activities, (3) Speech therapy to relearn muscle control and coordination to produce speech and (4) Psychotherapy to learn coping strategies and new behavioral skills to improve mood disorders or address personality changes. All of these are also available at St. Luke’s Medical Center.