ENCEPHALITIS

DEFINITION

Encephalitis, an inflammation of the brain parenchyma,.This is characterized by abscess formation. This is a serious condition sometimes even fatal
Cerebritis describes the stage preceding abscess formation and implies a highly destructive bacterial infection of brain tissue, whereas acute encephalitis is most commonly a viral infection with parenchymal damage varying from mild to profound.

CAUSES

• The etiology of encephalitis is usually infectious, but may be noninfectious, such as the demyelinating process in acute disseminated encephalitis.
• Infectious etiologies: Viral agents, such as HSV type 1 and 2 (almost exclusively in neonates), VZV, EBV, measles virus (PIE and SSPE), mumps, and rubella are spread through person-to-person contact. Human herpes virus 6 may also be a causative agent.
• Ticks and mosquito transmits epidemic encephalitis
• Non epidemic encephalitis can occur as a result of complication of chicken pox or mumps.
• Bacterial pathogens, such as Mycoplasma species and those causing rickettsial or catscratch disease, are rare and invariably involve inflammation of the meninges
• Encephalitis due to parasites and fungi
• Encephalitis due to Toxoplasma gondii.
• The CDC confirmed that West Nile virus can be transmitted by means of an organ transplant and via blood transfusions.

TYPES

• Herpes simplex virus encephalitis
• Artropod borne virus encephalitis
• Fungal encephalitis

(EXPLAINED….. IN ANOTHER POSTS)

PATHOPHYSIOLOGY: (STEP BY STEP PROCESS)

1. Portals of entry are virus specific. Many viruses are transmitted by humans, although most cases of HSE are thought to be reactivation of the herpes simplex virus (HSV) lying dormant in the trigeminal ganglia. Mosquitoes or ticks inoculate arbovirus, and rabies virus is transferred via animal bite. With some viruses, such as varicella-zoster virus (VZV) and cytomegalovirus (CMV), an immunocompromised host is a key risk factor.
2. The virus replicates outside the CNS and gains entry either by hematogenous spread or by traveling along neural (rabies, HSV, VZV) and olfactory (HSV) pathways.
3. Once across the blood-brain barrier, the virus enters neural cells, with resultant disruption in cell functioning,
4. Perivascular congestion, hemorrhage, and inflammatory response diffusely affecting gray matter disproportionately to white matter.

ASSESSMENT AND DIAGNOSTIC FINDINGS

• History collection and physical examination-History collection usually includes the history of intake of any immunosuppressive drugs,immunosupression associated with AIDS,occupational and travel history may indicate fungal infestation.
• Infections caused by H Capsulatum and C Immituswill demonstrate fungal antibodies in the serological tests
• The CSF will show high white cell and protein levels,glucose levels are decreased.C Neoformans are identified in CSF culture.Candida is also identified from CSF cultures
• MRI is indicated to detect hemorrhage,abscess or inflammation.

TREATMENT
Pre hospital Care:

• Evaluate and treat for shock or hypotension. Administer a crystalloid infusion until the patient is euvolemic.
• Consider airway protection in patients with an altered mental status.
• Consider seizure precautions. Treat seizures according to usual protocol (i.e., lorazepam 0.1 mg/kg given intravenously [IV]).
• Stabilize alert patients with normal vital signs by administering oxygen, securing IV access, and providing rapid transport to the ED.

Emergency Department Care:

• With the important exceptions of HSE and varicella-zoster encephalitis, the viral encephalitides are not treatable beyond supportive care. Treatments for T gondii and CMV encephalitis are available but generally not initiated in the ED.
• The goal of treatment for acutely ill patients is administration of the first dose or doses acyclovir with or without antibiotics or steroids as quickly as possible.
• The standard for acute bacterial meningitis is the initiation of treatment within 30 minutes of arrival.
• Consider instituting an ED triage protocol to identify patients at risk for HSE.
• Collect laboratory samples and blood cultures before the start of IV therapy. Even in uncomplicated cases of encephalitis, most authorities recommend a neuroimaging study (eg, MRI or, if not available, a contrast-enhanced head CT scan) before LP.
• General measures: Manage fever and pain, control straining and coughing, and avoid seizures and systemic hypotension.
• In otherwise stable patients, elevating the head and monitoring neurologic status usually are sufficient.
• When more aggressive maneuvers are indicated, some authorities favor the early use of diuresis (eg, frusemide 20 mg IV, mannitol 1 g/kg IV) provided circulatory volume is protected. Dexamethasone 10 mg IV q6h helps in managing edema surrounding space-occupying lesions. Hyperventilation (PaCO2 30 mm Hg) may cause a disproportional decrease in cerebral blood flow (CBF), but it is used to control increasing ICP on an emergency basis.
• Intraventricular ICP monitoring is controversial because some authorities believe dangerous focal edema with a pressure gradient between the temporal lobe and the subtentorial space usually is not detected by the monitor, leading to a false sense of security. In fact, monitor placement may potentially aggravate a pressure gradient.

MEDICAL MANAGEMENT

• Medical management is usually directed at the causative organisms.
• Seizures are controlled by standard antiseizure medications.
• Increased ICP is controlled by repeated lumbar puncture and shunting of the CSF>
• Antifungal agents are usually administered.Eg.Amphotericin B. IV.Common side effects are fever,chills body aches,hypotension and renal insufficiency.
• Fluconazole is administered in combination with Amphotericin B.The potencial side effects are nausea vomiting etc..The leucocytes and the platelet count should be monitored cautiously

PHARMACOLOGICAL THERAPY:
The goals of pharmacotherapy are to reduce morbidity and prevent complications.

• Antivirals:The goal of the use of Antivirals for HSE and varicella-zoster encephalitis is to shorten the clinical course, prevent complications, prevent the development of latency and/or subsequent recurrences, decrease transmission, and eliminate established latency.
• Acyclovir (Zovirax)Has demonstrated inhibitory activity directed against both HSV-1 and HSV-2, and infected cells selectively take it up.
• Corticosteroids:Anti-inflammatory agents used for treatment of postinfectious encephalitis and acute disseminated encephalitis. These drugs are commonly presented as treatment alternatives, though supporting data are limited.
• Dexamethasone (Decadron, Dexasone)Used to treat various allergic and inflammatory diseases. May decrease inflammation by suppressing migration of polymorphonuclear leukocytes and reversing increased capillary permeability

NURSING DIAGNOSIS

• Nursing measures for the early identification of ICP
• Administration of non opiod analgesics,limiting the environmental stimuli and positioning the patient.
• Administration of Diphenhydramine (Benadryl)and acetaminophen 30 minutes before giving amphotericin B may reduce flu like symptoms.
• If renal insufficiency develops the dose should be monitored.Increasing levels of serum creatinine and BUN indicates renal insufficiency
• Provide psychological support to the family members and the patient
• Community support to the patient and the family
• Mosquito control should be practiced,including cleaning the rain gutters,removing old tyres,and removing water where mosquitoes can breed ,insect repellants should be used.
• If cerebral edema is there diuretics(mannitol)and corticosteroids (Dexamethasone) are used to control it.
• In the initial stage many patients requires intensive careFor maximal benefit antiviral medications should be used before the onset of coma
• Seizure medications should be used before the onset of coma.
• Prophylactic treatment with antiseizure medications

NURSING MANAGEMENT

1>Acute pain related to headache and muscle and joint aches as manifested by general discomfort of head,joints,and muscles,apathy,grimacing and movement.

• Administer mild analgesics as prescribed,assist patient to position of comfort in the bed to relieve pain.
• Encourage gentle motion and leg exercises to reduce joint stiffness and to reduce joint stiffness and to promote circulation.
• Massage muscles as needed or requested to promote comfort and to show a caring attitude
• Control environment to encourage rest because pain can be exhausting to the patient

2>Hyperthermia related to infection and abnormal temperature regulationby hypothalamus from increased ICP as manifested by increased temperature and chills.

• Assess the temperature of the client
• Carryout general measures to control fever
• If prescribed a hypothermia blanket to reduce the fever because an elevated temperature increases brain metabolism and increases the risk of seizures or increased ICP
• Reduce temperature to prevent shivering. Which can cause a rebound effect and arise rather than lower the effect.
• Administer medications as prescribed by the physician

3>Decreased sensory perception related to decreased LOC as manifested by inaccurate interpretation of environment,signs of fear and anxiety ,disorientation and restlessness.

• Assess the LOC to determine extent of the problem
• Administer sedative medications as ordered to reduce fear and anxiety
• Keep room quiet and lights dim,use calm,reassuring approach to avoid stimulating or frightening the patient.
• Assist and support patient during uncomfortable or frightening diagnostic procedures.

4>Ineffective therapeutic regimen related to possible sequalae of condition as manifested by motor or sensory problems and activity limitations

• Monitor for residual effects of the conditions such as vision,hearing activity and cognitive problems to determine appropriate referrals
• Inform patient and others that residual problems often improve overtime to reduce anxiety.
• Arrange for postoperative care if required so that patient needs are met.

5>Potential complications.
Seizure activity related to cerebral irritation.

• Monitor for seizure activity so that interventions can be started immediately
• Keep the side rails up and padded up to protect if a seizure activity occurs
• Administer sedatives and antiseizure drugs if ordered by the physician
• Reduce fever to decrease brain s oxygen demand
• Carry out interventions to treat underlying causes of inflammatory brain condition to prevent seizure activity

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