diease

Encephalitis


OVERVIEW OF Encephalitis :

Encephalitis is inflammation of the active tissues of the brain caused by an infection or an autoimmune response. The inflammation causes the brain to swell, which can lead to headache, stiff neck, sensitivity to light, mental confusion and seizures. The disease might be due to infectious or Autoimmune


CAUSES :

Infectious:

Infectious encephalitis is typically caused by a viral infection. Vaccines for measeles mumps, rubella and chcken pox have reduced the rate of encephalitis from these diseases, but other viruses can cause encephalitis. The most common causes of viral encephalitis are herpes simplex virus 1 and 2 varicella zoster virus and enteroviruses, which cause gastrointestinal illness.

Encephalitis can also result from certain viruses carried by mosquitoes, ticks and other insects or animals such as:

Japanese encephalitis virus

West nile fever

La Crosse virus

St. Louis virus

Equine viruses

Powassan virus

Chikungunya

Zika virus

Other infectious microorganism include:

The American Equine Encephalitides

The alphavirus genus contains 4 viruses which produce encephalitis; EEE, WEE, VEE and Everglades. The Everglades virus is related to EEE but is restricted to the state of Florida in the U.S.A. EEE and WEE plays an important role in the transmission of the diseas between  mosquitoes and birds, similarly VEE between mosquitoes and rodents.

The disease manifestation include flu like symptoms in the earlier stages. The probability of developing encephalitis vary widely between the different viruses; it is highest for the EEE and lowest for the VEE.

No specific therapy is available against these viruses. Although inactivated vaccines have been prepared by the U.S. army against these viruses, they are not available for issue to the public at large and their efficacy had yet to be proven.  Public warnings should be issued when these viruses are prevalent.In cities with highest amount of population vector control is indicated.
 

The family of arbovirus include toga virus,

Flavi virus

Bunya virus

Reovirus

Rhabdeovirus

Orthomyxiviridae

Togaviridae

Autoimmune encephalitis:

Autoimmune encephalitis occurs when a person’s own antibodies or immune cells attack the brain. Antibodies may target specific proteins or receptors in the brain, which determine the type of autoimmune encephalitis:

In anti-NMDA receptor encephalitis, the immune system targets the NMDA receptors in the brain.

In VGKC-complex antibody encephalitis, the immune system targets the VGKC brain protein complex that includes subtypes LGI-1 and CASPR2.

GABA-A and GABA-B receptors may also be targeted.

 


COMMON CLINICAL SIGNS AND SYMPTOMS :

Headache

Vomiting

Fatigue

Sleepiness

Seizure

Cerebral edema

Arthralgia

Febrile illness

Heamorrhagic fever which results in damage to the blood vessels. severe bleeding is manifested.

Excessive sleepiness

Confusion and disorientation

Irritability

Anxiety

Psychosis

Hallucinations

Memory loss

Other behavioral changes

Cognitive impairment

 

 


DIAGNOSTIC :

Detection of virus-neutralizing antibodies in combination with recent travel history to an endemic area may be meaningful.

Immunosorbent assay:

 Detect the virus specific IgM or IgG antibodies.

Greater than fourfold rise in titer between acute and convalescent sera  and  cerebo spinal fluid containing virus specific IgG or IgM or both are the diagnostic features.

Real-time polymerase chain reaction (RT-PCR):

 It is valuable in the early confirmation of arbovirus infections. However, the value of RT-PCR is limited to diagnosis in the viraemic phase, with later infection requiring serology.

Direct immunofluorescence assay :

to detect IgM has a high sensitivity and specificity and is used in the latter stages. However, the use of these tests in the tropics may be limited by financial constraints.

A normal erythrocyte sedimentation rate- and a negative rheumatoid factor are useful to differentiate virus arthritis from rheumatoid arthritis. Extensive, symmetrical joint involvement, particularly of the metacarpophalangeal and proximal joints, the presence of rheumatoid nodules or anti-cyclic citrullinated peptide (anti-CCP) antibodies favours rheumatoid arthritis over  with chronic arthropathy. The presence of lower limb asymmetrical joint involvement with axial skeletal affliction favours the diagnosis of spondyloarthropathy

Lumbar puncture:

The spinal fluid is tapped and it is sent to the laboratory for further investigations.

Needle biopsy:

It can be used to collect the brain tissue and examination is done under microscope.

Imaging tests: CT scan, MRI scan SPECTs and  PET scans help doctors locate the tumor and determine if it is cancerous or benign. Your doctor may also look at other parts of the body, such as the lungs, colon or breasts, to identify where the tumor started.

Neurological exam: During a neurological exam, your doctor will look for changes in your balance, coordination, mental status, hearing, vision and reflexes. These changes can point to the part of your brain that may be affected by a tumor.

Intracranial pressure monitoring:

The ICP measures the pressure created inside the skull.

 


TREATMENT AND PROGNOSIS :

Supportive measures by IV fluids, electrolytes if needed breathing support can be given.

Medication

The following medications are used to treat the following brain tumour:

  • Steroids such as dexamethasone are used in the treatment of brain tumour. Intake of steroid result in increase chances for peptic ulcer hence famotidine and pantaprazole are used to treat the disease.
  • Furosemide and mannitol can be used to treat the brain edema and swelling. Anticonvulsants are used to treat or prevent the edema.  The most common cause include phenytoin,valproic acid and carbamazepine.
  • A breathing tube, urinary catheter, or feeding tube may be necessary if the person’s encephalitis has caused loss of consciousness.

Supportive measures:

  • Bed rest
  • Plenty of fluids
  • Anti-inflammatory drugs — such as acetaminophen, ibuprofen and naproxen sodium — to relieve headaches and fevers

Antiviral drugs

Encephalitis caused by certain viruses usually requires antiviral treatment.

Antiviral medications commonly used to treat encephalitis include:

  • Acyclovir
  • Ganciclovir
  • Foscarnet

Immunotherapy:

It is a drug treatment that uses your immune system to fight cancer. This immunotherapy boost those cells and helps the body to fight against the encephalitis.

 

 

 

 


PREVENTION :

  • Keep your vaccinations up to date, especially while travelling to the areas of encephalitis virus prone.
  • Use proper hygiene and hand-washing to help prevent the spread of viruses and bacteria.
  •  Avoid mosquito and tick exposure


REFERENCE :

https://www.hopkinsmedicine.org/health/conditions-and-diseases/encephalitis

https://www.mayoclinic.org/diseases-conditions/encephalitis/symptoms-causes/syc-20356136

https://www.ecdc.europa.eu/en/japanese-encephalitis/prevention-and-control