Encephalitis, Meningitis And Brain Abscess

INTRODUCTION

EncephalitisDefinition: An acute febrile syndrome marked by

inflammation of the brain and its coverings. Incidence: It's a rare disease that occurs in

approximately 0.5 per 100,000 individuals — most commonly in children, the elderly, and people with weakened immune systems (e.g., those with HIV/AIDS or cancer). Infants younger than 1 year and adults older than 55 are at greatest risk of death from encephalitis

Etiology:• Encephalitis can be caused by bacterial infection and, most

often, viral infections.• Several viruses e.g., arbovirus, enterovirus, adenovirus,

herpes virus, mumps virus. • The mode of transmission is usually a mosquito bite, but ticks

and amebae may also transmit the virus.• Some forms of the virus (e.g., herpes virus) may be spread by

direct contact with nasal excretions or open lesions.• A more rare secondary encephalitis may occur as a

complication of another primary viral infection, such as measles, chickenpox, or rubella.

• It is also caused by exogenous poisoning such as that which follows the ingestion of lead or arsenic or inhalation of carbon monoxide.

 

Pathophysiology: (Arbovirus, Enterovirus, Adenovirus, Herpes virus,

mumps) virus invades blood stream, lymph nodes, bone marrow and most organs within 24 hours of contact.

Within 48 hours, lymphocyte destruction and necrosis of

lymph nodes. By day 4, macrophages have replaced the destroyed

lymph nodes, bone marrow is depleted and cytoplasm and megakaryocyte nuclei are degenerating.

By day 6, petechial hemorrhages, lymphocytic

perivascular cuffing, gliosis and neural necrosis. Cerebral dysfunction

Clinical manifestation: • Symptoms in milder cases of encephalitis

usually include:• fever• headache• poor appetite• loss of energy• a general sick feeling

In more severe cases of encephalitis, a person is more likely to experience high fever and any of a number of symptoms that relate to the central nervous system, including:

• severe headache• nausea and vomiting• stiff neck• confusion• disorientation• personality changes• convulsions (seizures)• problems with speech or hearing• hallucinations• memory loss• drowsiness

Diagnostic tests:• Clinical evaluation- History of exposure, nuchal rigidity,

positive kernig’s sign, pathological refluxes, muscle weakness, paralysis.

• Lumbar puncture- Elevated pressure, cerebrospinal fluid, WBC’s elevated, proteins slightly elevated, glucose normal.

• Serology- Increase in antibody titer early in diseases.

• Imaging tests, such as computed tomography (CT) scans or magnetic resonance imaging (MRI), to check the brain for swelling, bleeding, or other abnormalities

• Electroencephalogram (EEG), which records the electrical signals in the brain, to check for abnormal brain waves

• Blood tests to confirm the presence of bacteria or viruses in the blood, and whether a person is producing antibodies (specific proteins that fight infection) in response to a germ

• Immunofluorescent stain of biopsy brain tissue positive for specific viruses.

Medical Management: • Vidaribine and Acyclovir for herpes virus

infections• sedatives for restlessness, • anticonvulsants for seizure activity, • Mannitol and corticosteroids to reduce

cerebral edema and inflammation.• Over-the-counter (OTC) medications, like

acetaminophen, can be used to treat fever and headaches.

Nursing management:• Maintenance of fluid and electrolytes• Maintenance of the airway • Oxygen to maintain blood gas • Maintain nutritional status • Adequate Rest • The patient is kept in bed and side rails are used,

if disorientation develops• Seizure precautions • Neurological assessment • Rehabilitation

Complications: Swelling of the brain can lead to permanent

brain damage and lasting complications like learning disabilities, speech problems, memory loss, or lack of muscle control.

Meningitis

Definition  An infection and inflammation of the

meninges of the brain and spinal cord resulting in altered neurological function.

Types of meningitis:• Viral meningitis• Pyogenic bacterial meningitis• Tuberculous meningitis

Viral meningitis Viral infection is the most common cause of

meningitis and usually results in a benign and self limiting illness requires no specific therapy.

Clinical features• Headache• Irritability• High pyrexiaInvestigations:• CSF• Glucose and protein levels• Lumbar puncture

Management:• There is no specific treatment and condition is

usually benign and self limiting. The patient should be treated symptomatically in a quite environment. Recovery usually occurs within days, although lymphocytic pleocytosis may persist in the CSF.

Pyogenic bacterial meningitis:• Many bacteria can cause meningitis but

some do so more frequently than others. Bacterial meningitis is usually secondary to bacteraemic illness, although infection may result from direct spread from an adjacent focus of infection in the ear, skull fractures or sinus.

Etiology:• Neisseria meningitides, haemophilus influenza

and streptococcus pneumoniae• Meningococcus (Neisseria meningitides) is the

most common cause of bacterial meningitis.• Spread is by the air -borne route, but close

contact is necessary. • Others like Otitis media

Pathophysiology: Pia-arachnoid is congested and infiltrated with inflammatory cells.

A thin layer of pus forms and this may later organize to form adhesions.

Obstruction to free flow of CSF leading to hydrocephalus and damage the cranial nerves.

The CSF pressure rises rapidly and protein content increases.

Secondary cerebral infarction.

Clinical Manifestations:

Diagnostic tests• Culture of CSF• Respiratory secretions• Lumbar puncture• CT scanMedications:• Parenteral benzyl penicillin(IV)• Penicillin antibiotics(e.g. Ampicillin)• Cephalosporin(eg.ceptraxone sodium)• Dexamethasone.• Anticonvulsant may be prescribed for seizures.

Tuberculous meningitis:                           Pathology Primary infection in childhood or as part of

military tuberculosis

Infection to the CSF path way Brain covered by greenish, gelatinous exudates

especially around the base and numerous scattered tubercles are found in the meninges.

Clinical features:

Investigations• CSF• Smear test• CT scan• Brain imaging

Management:• Chemotherapy should be started using one of the regimens

including pyrazinamide.• Steroids

Surgical managements:• Surgical ventricular drainage may be needed, if obstructive

hydrocephalus develops.

Brain Abscess•          Brain abscess (or cerebral abscess) is an abscess

caused by inflammation and collection of infected material, coming from local (ear infection, dental abscess, infection of paranasal sinuses, infection of the mastoid air cells of the temporal bone, epidural abscess) or remote (lung, heart, kidney etc.) infectious sources, within the brain tissue.

Etiology:• Extension of existing cranial infection(e.g. Ear

infection, Sinusitis,Osteomyelitis)• Penetrating head wounds• Blood borne transmission from a distant

infection (e g. bacterial endocarditis, abdominal/pelvic infections etc)

• IV drug abuse• Immunodeficiency.

Risk Factors• Blood-borne infections (e.g., bacterial

endocarditis, peritonitis)• Immunodeficiency infections• Infections of the face and head(e.g., otitis

media, sinusitis, mastoiditis, acne, or abscesses of teeth or gums)

• IV Drug use.• Open head injury.

Pathophysiology: The brain produces a poorly localized

inflammatory response to the invading pathogen.

Brain tissue liquefies and becomes necrotic, producing a cystic mass.

As the mass enlarges, it increases intracranial pressure

Growth of tumor, memory impairment, seizures

Clinical Manifestations:• Headache• Nausea• Vomiting• Seizures• Altered mental status• Drowsiness• Nuchal rigidity• Low grade fever can occur. The duration of symptoms varies considerably from

hours to weeks.

Diagnostic Tests:• CT Scan/MRI- Visualization of abscess.

Medical management:• IV antibiotics • Steroids • Anticonvulsants

Nursing Management:• Monitoring for hyponatremia• Prevention of complications of extended bed

rest [e.g., range of motion (ROM) exercises and turning].

• Rehabilitation.

Prognosis• Once an almost always fatal disease before the CT era,

now, if the abscess is treated before the person goes into a coma, then the death rate has been estimated from 5% to 20% although it is greater in cases of multiple abscesses, when raised intracranial pressure is observed and depending on the level of neurological dysfunction on presentation. Early treatment and the patients overall health has an effect on prognosis. Other factors include: antibiotic resistance or the abscess location. An abscess deep within the brain is more difficult to treat than others.

Complications:• The illness is progressive and usually

fatal is left untreated. With treatment, the mortality rate is 30%, and more than half of survivors suffer some neurological sequelae.

Conclusion