Meningoencephalitis

Description, Causes and Risk Factors:

Meningoencephalitis is a fatal medical condition that is characterised by an inflammation of the meninges of the brain and spinal cord. It may be caused by a pathogenic infection by a disease vector that can penetrate the barriers of the Central nervous system. This term generally refers to a persistent inflammatory process characterized by thickening of the arachnoid membrane and dural adhesions.

The disease has viral & bacterial, and parasitic cause:

Viral causes:

• Acute viral encephalitis (caused by a direct viral infection of the brain).

• Post-infectious encephalitis (also called acute disseminated encephalomyelitis) which is an autoimmune process, following a viral infection elsewhere in the body.

• Herpes simplex virus (HSV) encephalitis is recognized worldwide as the most frequent infectious encephalitis, and the only one with a validated specific treatment.

• Other common viral causes are Herpes zoster, Epstein-Barr virus, mumps, measles, Rubella, Enteroviruses, Cytomegalovirus (CMV), adenovirus, influenza virus, poliovirus, rabies, arbovirus (eg California virus, Japanese B encephalitis, St. Louis encephalitis, West Nile encephalitis, Eastern and Western equine encephalitis), Reovirus (Colorado tick fever virus), parvovirus B19.

Bacterial causes:

• Tuberculosis (TB), mycoplasma, Listeria, Lyme disease, Bartonella henselae (cat scratch fever), Leptospira, Brucella, Legionella.

• Rickettsial: Rocky Mountain spotted fever, endemic typhus, epidemic typhus, Q fever, human monocytic ehrlichiosis.

• Fungal: Cryptococcosis, coccidioidomycosis, histoplasmosis, North American blastomycosis, Candidiasis.

• Tick-borne encephalitis is a rapidly growing public health problem in Europe and other parts of the world. It is caused by tick-borne encephalitis virus, a member of the family Flaviviridae.

Parasitic causes: Human African trypanosomiasis, Toxoplasma gondii, Naegleria fowleri, Echinococcus granulosus, schistosomiasis. Primary amoebic meningoencephalitis is caused by infection from an amoeba such as Naegleria fowleri or Balamuthia mandrillaris.

Risk factors include prior surgery, infections, trauma, subarachnoid hemorrhage, and chemical irritation.

The prognosis depends on the age of the patient and the underlying aetiology. The poorest prognosis for meningoencephalitis occurs in patients with HSV encephalitis and subacute sclerosing panencephalitis.

Symptoms:

Symptoms include:

Headaches.

• Cognitive dysfunction: Acute memory, speech and orientation disturbance.

• Behavioral changes: Disorientation, hallucinations, psychosis, personality changes, agitation.

• Nominal aphasia.

• Dysphasia.

• Hemiparesis.

• Seizures.

Clinical features vary with the site of inflammation, but include cranial neuropathies, radiculopathies, and myelopathies.

Diagnosis:

Diagnosis should be based on medical history and examinationfollowed by CSF analysis for protein and glucose levels, cellular analysis, and identi?cation of the pathogen by polymerase chain reaction ampli?cation (level A) and serology (level B).

• Neuroimaging, preferably by MRI, is essential(level B). Lumbar puncture can follow neuroimaging when immediately available, butif this cannot be performed immediately, LP should be delayed only under unusualcircumstances.

• Brain biopsy should be reserved only for unusual and diagnosticallydi?cult cases.

• Electroencephalography is generally regarded as a nonspeci?c investigation, although it is still sometimes auseful tool in certain situations.

Treatment:

There is no specific treatment for other viral causes and the emphasis of treatment is supportive. Intravenous broad-spectrum antibiotics may be given to treat secondary bacterial infections. Intravenous fluids need to be given very carefully in order not to aggravate cerebral edema.

The availability of aciclovir, an excellent anti-HSV therapy, has led to early initiation of the treatment with substantial improvement in the clinical outcome of HSE. It is yet unknown if the availability of newer antiviral therapy (ribavarin and pleoconaril) will substantially change the natural course. Immunization is reserved for some cases.

Adequate vector control and environmental sanitation are essential to prevent large outbreaks.

NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.

DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.