Encephalitis

Brain disease that is characterized as an acute inflammation of the brain with flu-like symptoms

Encephalitis
Synonyms	N/A
Pronounce	N/A
Field	Neurology, infectious disease
Symptoms	Headache, fever, confusion, stiff neck, vomiting
Complications	Seizures, trouble speaking, memory problems, problems hearing
Onset
Duration	Weeks to months for recovery
Types	Herpes simplex, West Nile, rabies, Eastern equine, others
Causes	Infection, autoimmune, certain medication, unknown
Risks
Diagnosis	Based on symptoms, supported by blood tests, medical imaging, analysis of cerebrospinal fluid
Differential diagnosis
Prevention
Treatment	Antiviral medication, anticonvulsants, corticosteroids, artificial respiration
Medication
Prognosis	Variable
Frequency	4.3 million (2015)
Deaths	150,000 (2015)

Encephalitis is the inflammation of the brain. The severity can be variable with symptoms including headache, fever, confusion, a stiff neck, and vomiting. Complications may include seizures, hallucinations, trouble speaking, memory problems, and problems with hearing.

Pathophysiology

Causes of encephalitis include viruses such as herpes simplex virus and rabies as well as bacteria, fungi, or parasites. Other causes include autoimmune diseases and certain medications. In many cases the cause remains unknown. Risk factors include a weak immune system. Diagnosis is typically based on symptoms and supported by blood tests, medical imaging, and analysis of cerebrospinal fluid. Certain types are preventable with vaccines. Treatment may include antiviral medications (such as acyclovir), anticonvulsants, and corticosteroids. Treatment generally takes place in hospital. Some people require artificial respiration. Once the immediate problem is under control, rehabilitation may be required. In 2015, encephalitis was estimated to have affected 4.3 million people and resulted in 150,000 deaths worldwide.

Signs and symptoms

Adults with encephalitis present with acute onset of fever, headache, confusion, and sometimes seizures. Younger children or infants may present with irritability, poor appetite and fever. Neurological examinations usually reveal a drowsy or confused person. Stiff neck, due to the irritation of the meninges covering the brain, indicates that the patient has either meningitis or meningoencephalitis.

Cause

Rabies virus

Fungal

Fungal encephalitis is relatively rare and usually affects people with weakened immune systems. Common fungal causes include Cryptococcus neoformans, Candida species, Aspergillus species, and Histoplasma capsulatum.

Parasitic

Parasitic infections that can cause encephalitis include toxoplasmosis, malaria, Trypanosoma species (such as those causing African trypanosomiasis), and Acanthamoeba species (which can cause granulomatous amoebic encephalitis).

Non-infectious Causes

Non-infectious causes of encephalitis include autoimmune encephalitis and paraneoplastic encephalitis. Autoimmune encephalitis involves the immune system attacking the brain, which can be triggered by an infection, tumor, or occur spontaneously without a known cause. Paraneoplastic encephalitis is a rare disorder where the immune system attacks the brain in response to an underlying tumor, typically a cancerous one.

Diagnosis

Spinal tap on a newborn

Diagnosing encephalitis can be challenging, as its presentation can vary widely and can mimic other neurological disorders. A combination of clinical history, physical examination, laboratory tests, and imaging studies are typically used to make a diagnosis. Key diagnostic tests and procedures include:

• Lumbar puncture (spinal tap): A lumbar puncture is used to collect cerebrospinal fluid (CSF) for analysis. This can help identify an infection or inflammation in the brain and spinal cord.
• Blood tests: Blood tests can help identify infections, measure inflammation, and check for autoimmune markers that could indicate autoimmune encephalitis.
• Neuroimaging: Brain imaging techniques such as computed tomography (CT) or magnetic resonance imaging (MRI) can help identify swelling or other abnormalities in the brain.
• Electroencephalogram (EEG): An EEG measures electrical activity in the brain and can help identify abnormal patterns that may suggest encephalitis.
• Brain biopsy: In rare cases, a small sample of brain tissue may be taken to help identify the cause of encephalitis. This is typically reserved for cases where other tests have not provided a clear diagnosis.

Treatment

Treatment for encephalitis depends on the underlying cause. For infectious encephalitis, antiviral or antibacterial medications may be used to target the specific pathogen. Supportive care, including fluid management, pain relief, and fever control, is also essential.

In cases of autoimmune or paraneoplastic encephalitis, treatments may include corticosteroids, intravenous immunoglobulin (IVIG), or plasma exchange to help reduce inflammation and suppress the immune response. In some cases, additional immunosuppressive medications or targeted therapies may be necessary.

Early diagnosis and treatment are crucial in improving outcomes for encephalitis patients. In severe cases, encephalitis can lead to long-term neurological complications, including cognitive impairments, seizures, and movement disorders.

Prevention

Preventing encephalitis involves reducing the risk of exposure to infections and practicing good hygiene. Some preventive measures include:

• Vaccination: Immunizations against certain viruses, such as measles, mumps, rubella, and Japanese encephalitis, can help protect against encephalitis caused by these infections.
• Mosquito and tick control: Using insect repellent, wearing protective clothing, and avoiding areas with high mosquito or tick populations can help reduce the risk of encephalitis caused by vector-borne infections.
• Handwashing and hygiene: Regular handwashing and practicing good hygiene can help prevent the spread of infections that may cause encephalitis.
• Avoiding contact with infected individuals: Limiting contact with people who have infections, particularly those that may cause encephalitis, can help reduce the risk of contracting the illness.
• Immunocompromised individuals should take extra precautions, including avoiding contact with sick individuals and practicing good hygiene, to minimize their risk of developing encephalitis.

Recovery and Rehabilitation

• Recovery from encephalitis can vary greatly depending on the severity of the illness, the underlying cause, and the patient's age and overall health. Some individuals may recover fully, while others may experience long-term neurological complications.
• During the recovery process, rehabilitation may be necessary to help patients regain lost skills and improve their quality of life. Rehabilitation programs can include:
• Physical therapy: Physical therapists can help patients improve strength, balance, and coordination, as well as help with mobility issues that may have arisen as a result of encephalitis.
• Occupational therapy: Occupational therapists can assist patients in relearning daily living skills, such as dressing, eating, and bathing, and help them adapt to any cognitive or physical impairments that may persist after encephalitis.
• Speech and language therapy: Speech-language pathologists can help patients regain their communication skills and address any swallowing difficulties that may have occurred as a result of encephalitis.
• Cognitive rehabilitation: Neuropsychologists and other rehabilitation specialists can work with patients to improve memory, attention, and problem-solving skills that may have been affected by encephalitis.
• Support groups and counseling: Emotional support and counseling can help patients and their families cope with the challenges and stress associated with encephalitis and its long-term effects.
• Regular follow-up appointments with healthcare providers are essential during the recovery and rehabilitation process to monitor progress and address any emerging concerns.

Prognosis

The prognosis for encephalitis patients can vary widely, depending on factors such as the cause of the illness, the severity of the infection, and the patient's age and overall health. Early diagnosis and treatment are crucial for improving the chances of a better outcome. Some individuals who experience encephalitis recover completely without any long-term complications. However, others may face lasting neurological problems, such as cognitive impairments, motor skill difficulties, or epilepsy. The severity of these issues can range from mild to severe. In some cases, encephalitis can be fatal. The risk of death is higher in certain groups, such as infants, the elderly, and those with compromised immune systems. The specific cause of encephalitis can also influence the likelihood of a fatal outcome. Long-term follow-up care is essential for encephalitis survivors, as complications and new health concerns may arise over time. Ongoing medical support, rehabilitation services, and emotional support can help patients and their families adjust to life after encephalitis and maximize their quality of life.

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