Encephalitis Explained
Table of Content
Introduction
Encephalitis is a life-threatening condition involving brain swelling (inflammation) caused by a bacterial or viral infection, an autoimmune response (where the immune cells mistakenly attack healthy brain cells), or an unknown cause. Brain inflammation can lead to symptoms such as headaches, light sensitivity, a stiff neck, seizures, and mental confusion. The cause and severity of the inflammation, the affected area of the brain, and the timing of treatment determine the degree and type of damage, impacting patient outcomes with either minor or major impairment.
Long-term consequences may include cognitive, physical, behavioural, and emotional problems (discussed below). According to neurologists, several factors increase the risk of developing encephalitis, such as age, a weakened immune system, geographical region, season, and autoimmune disease. Encephalitis is non-contagious (it is not transmitted from one person to another).
Types of Encephalitis
Infectious Encephalitis
Viruses are the most common cause of infectious encephalitis, including human herpes viruses (such as herpes simplex virus, which causes cold sores, and varicella-zoster virus, which causes chickenpox), cytomegalovirus, Epstein-Barr virus, and viruses responsible for rashes like rubella, mumps, and measles. Other culprits include throat and chest viruses (enteroviruses and the flu), gut viruses (enteroviruses and echo virus), tick-borne encephalitis virus, and insect-borne viruses (West Nile virus and Japanese encephalitis virus).
In rare cases, bacteria (e.g., Listeria, pneumococcal, meningococcal, and Mycoplasma), fungi (e.g., Candida, Cryptococcus, and Histoplasma), and parasites (e.g., Toxoplasma and malaria parasites) can also cause encephalitis.
Autoimmune Encephalitis
Autoimmune encephalitis occurs when the immune system mistakenly attacks healthy brain cells. This can be triggered by a prior infection (post-infection encephalitis), a cancerous or non-cancerous tumour (paraneoplastic syndrome), or the presence of specific antibodies in the blood, such as N-methyl D-aspartate receptor (NMDAR), which causes anti-NMDA receptor encephalitis (more common in young individuals), or an unknown cause.
Symptoms of Encephalitis
The symptoms of infectious encephalitis develop quickly, while those of autoimmune encephalitis progress more slowly.
Infectious encephalitis starts with flu-like symptoms, such as headache, fever, muscle/joint aches, and fatigue. Within hours or days, more severe symptoms emerge, including neck stiffness, confusion, hallucinations, seizures, muscle weakness, limited mobility of the face or certain body parts, speech/hearing problems, and loss of consciousness.
In infants and young children, additional symptoms may include:
- Protruding soft spots on the skull (spaces between skull bones due to incomplete bone formation)
- Irritability
- Difficulty feeding or refusing to wake for feeding
- Nausea and vomiting
Risk Factors for Encephalitis
- Infants and older adults
- Individuals with cancer or a weakened immune system (e.g., HIV/AIDS)
- People living in areas where ticks and mosquitoes are common (especially in the summer or fall)
High-risk individuals should be vigilant about symptoms and seek immediate medical attention. They should also take precautions to minimize exposure to potential causative agents in high-risk areas and maintain a healthy immune system through exercise and a nutritious diet.
Diagnosis
Several tests are performed to diagnose encephalitis:
Clinical Evaluation and Patient History
A physical exam assesses nerve function, motor/sensory function, balance, coordination, mood swings, and mental status. A medical history is taken, reviewing recent activities, including exposure to ticks, insects, or animals, contact with sick individuals, travel history (to areas where encephalitis is prevalent), symptoms and their duration, and pre-existing medical conditions. Early diagnosis is critical, as symptoms can escalate rapidly to cause brain damage, loss of speech/hearing/vision, or death.
Laboratory Tests
- CSF Analysis
All suspected encephalitis patients undergo a lumbar puncture to collect cerebrospinal fluid (CSF), a process where a needle is inserted into the lower back under local anaesthesia to remove the protective fluid surrounding the brain and spinal cord. CSF analysis helps confirm the diagnosis. In viral encephalitis, CSF shows an elevated white blood cell count, primarily lymphocytes, indicating inflammation. Further tests on CSF, such as microbial culture and PCR analysis, help detect viral or bacterial causes.If CSF analysis is inconclusive, blood, urine, and other body fluids are tested for viruses or infectious agents. - Autoimmune Encephalitis Testing
If infectious encephalitis is ruled out, autoantibody testing is recommended when an autoimmune encephalitis phenotype is suspected, such as NMDAR antibody encephalitis or LGI-1 antibody encephalitis. A neurologist decides which autoantibody test should be performed. - Imaging Tests
Magnetic Resonance Imaging (MRI) is the gold standard for diagnosing encephalitis and is abnormal in 90% of HSV encephalitis cases. However, it may appear normal or only slightly abnormal in autoimmune encephalitis. In cases of paraneoplastic syndrome (e.g., NMDAR antibody encephalitis linked with ovarian teratoma), CT, PET, and ultrasound scans may also be used. - Electroencephalography (EEG)
An EEG records abnormal brain activity (seizures), though it is non-specific, as abnormal activity can be present in many cases of encephalopathy. - Brain Biopsy
While CSF PCR testing has reduced the need for brain biopsy, it may still be recommended if the diagnosis remains unclear after extensive testing, especially if abnormal tissue is seen on imaging.
Treatment
Treatment for encephalitis should start immediately. For viral causes (e.g., HSV or chickenpox), anti-viral medications like acyclovir (for HSV) or ganciclovir (for CMV encephalitis) are administered intravenously. If the cause is bacterial or fungal, appropriate anti-bacterial or anti-fungal medications are given.
For autoimmune encephalitis, corticosteroids, immunoglobulin therapy, or plasmapheresis (a procedure to remove harmful substances from the blood) may be used. In some cases, long-term immunosuppressive treatment with medications like azathioprine, rituximab, or tocilizumab is required. If an underlying tumour is the cause, treatment may include radiation, chemotherapy, or surgery.
Supportive care in the hospital is essential, especially for severe cases, and includes mechanical ventilation, intravenous fluids, pain management, anti-seizure medications, and anti-inflammatory treatments.
If encephalitis leads to complications, follow-up therapy is necessary, including rehabilitation to improve memory, cognitive function, physical therapy to enhance coordination and mobility, speech therapy, and psychotherapy to manage mood disorders.
Potential Long-term Effects of Encephalitis
- Cognitive Changes
Patients may experience difficulties with memory, attention, problem-solving, language, and decision-making. They may struggle with recalling recent events, learning new skills, or following directions, and may have trouble concentrating and staying organized. - Emotional and Behavioural Changes
Patients can experience mood extremes, ranging from excessive happiness to sadness or emotional numbness. They may have anger outbursts, become anxious, and feel frustrated with their inability to return to work or engage in regular social activities. These changes can lead to misunderstandings, as patients may have difficulty reading emotions in others. - Physical Changes
Fatigue, pain, headaches, balance and coordination issues, and difficulty with speech and swallowing can significantly affect daily life. Seizures may persist even after recovery, and patients may experience sensory changes (vision, touch, smell, sound) and problems with incontinence. Hormonal imbalances can also lead to weight gain, mood swings, and difficulty regulating body temperature.
Prognosis
Mild cases of encephalitis can result in a full recovery, but severe cases can lead to permanent challenges, such as seizures, memory loss, blindness, and hearing loss. Despite advances in diagnosis and treatment, encephalitis remains fatal in about 10% of cases. Comprehensive rehabilitation, involving specialists in speech therapy, neurology, occupational therapy, and nutrition, is essential for improving long-term outcomes.
Prevention and Vaccines
- Practice good hygiene, including regular handwashing with soap and water.
- Get vaccinated against viruses known to cause encephalitis (e.g., Japanese encephalitis, MMR).
- Take precautions to avoid tick and mosquito bites: wear protective clothing, use insect repellent, and treat clothing with permethrin.
- Keep environments dry to prevent mosquito breeding and use screens to keep them out.
Conclusion
Encephalitis is characterized by brain inflammation, often caused by viral infections or autoimmune responses, leading to neurological, behavioural, and physical disruptions. Early diagnosis and treatment are critical to preventing severe outcomes, including brain damage or death. Although encephalitis cannot be fully prevented, vaccination can reduce the risk of certain viral causes. Prompt treatment, followed by comprehensive rehabilitation, can help patients recover and manage long-term effects.
For more information or specialized care for encephalitis, consider reaching out to the expert neurologists at Kauvery Hospital. With branches in Chennai, Hosur, Salem, Tirunelveli, and Trichy, we’re here to support your health needs with comprehensive diagnostics and personalized treatment plans. Your well-being is our priority at Kauvery Hospital.
Frequently Asked Questions
What is the main cause of encephalitis?
Encephalitis is most commonly caused by viral infections such as herpes simplex virus, Japanese encephalitis virus, and enteroviruses. It can also result from autoimmune disorders, bacterial or fungal infections, or in rare cases, have no identifiable cause.
How do you know if someone has encephalitis?
Early signs include headache, fever, fatigue, and confusion. Severe cases may involve seizures, hallucinations, loss of consciousness, and behavioural changes. Medical tests like MRI, lumbar puncture, and blood tests confirm the diagnosis.
Can encephalitis be cured completely?
Mild cases may resolve with full recovery, while severe cases can cause lasting complications. Early treatment improves the chances of recovery and reduces the risk of permanent damage.
What are the long-term effects of encephalitis?
Long-term effects can include memory loss, speech difficulties, fatigue, mood changes, seizures, and coordination problems. Some patients may need ongoing therapy and support.
Who is at risk of encephalitis?
Infants, older adults, people with weakened immune systems, and those living in mosquito- or tick-prone areas are at higher risk. Certain autoimmune conditions also increase the risk.
What is the difference between encephalitis and meningitis?
Encephalitis is inflammation of the brain, while meningitis is inflammation of the protective membranes around the brain and spinal cord. Both share similar symptoms but require different treatments.
Kauvery Hospital is globally known for its multidisciplinary services at all its Centers of Excellence, and for its comprehensive, Avant-Grade technology, especially in diagnostics and remedial care in heart diseases, transplantation, vascular and neurosciences medicine. Located in the heart of Trichy (Tennur, Royal Road and Alexandria Road (Cantonment), Chennai (Alwarpet & Vadapalani), Hosur, Salem, Tirunelveli and Bengaluru, the hospital also renders adult and pediatric trauma care.
Chennai Alwarpet – 044 4000 6000 • Chennai Vadapalani – 044 4000 6000 • Trichy – Cantonment – 0431 4077777 • Trichy – Heartcity – 0431 4003500 • Trichy – Tennur – 0431 4022555 • Hosur – 04344 272727 • Salem – 0427 2677777 • Tirunelveli – 0462 4006000 • Bengaluru – 080 6801 6801
