Meningitis and Encephalitis

Meningitis

Definition: > Meningitis is an inflammation of the

protective membranes covering the brain and spinal cord, known collectively as the meninges.

> The inflammation may be caused by infection with viruses, bacteria, fungus and less commonly by certain drugs.

Viral Etiologies

Septic Meningitis: common causesAge Causes

Neonates Group B Streptococci, Escherichia coli, Listeria monocytogenes

Infants Neisseria meningitidis, Haemophilus influenzae, Streptococcus pneumoniae

Children N. meningitidis, S. pneumoniae

Adults S. pneumoniae, N. meningitidis, Mycobacteria, Cryptococci

Cerebral shunt Extraventricular drain

Risk Factors

In these cases, infections with staphylococci as well as by pseudomonas

Risk Factor

Children younger than age 5

Risk Factors

Risk Factors:

Pregnancy Working with animals

Compromised immune system

Risk Factors:

diabetes mellitus

Genetic predisposition Environmental or viral stressor Destruction of alpha and beta cells of the

pancreas

Pancreatic transplantation

Failure to produce insulin Production of excess glucagon

Production of glucose from protein and fat stores

Wasting of lean body mass

Chronic elevations in blood glucose levels

Increased ketones

Acidosis

Fatigue

Weight loss

Acetone breath odorIncreased osmolarity

due to glucose

Elevated blood glucose level

Polydipsia Polyuria Polyphagia

Weight lossSmall-vessel disease Accelerated atherosclerosis Impaired immune function

Diabetic retinopathy Diabetic nephropathy Diabetic retinopathy Infection Delayed wound healing

Dialysis, transplantation

End- stage renal failureLaser

therapy

Hypertension Coronary artery disease

Increased low-density lipoprotein

levels

Loss of vision, blindness

Symmetrical loss of sensation

Numbness and tingling in the extremities

Wasting of intrinsic muscles

Charcot’s joint (neopathic joint

disease)

Autonomic neuropathy

Diabetic and foot ulceration

Insulin, meal planning, exercise

Key: = treatment

Pathophysiology

Bacteria reach the meninges through:

bloodstream direct contact between the meninges either through the nasal cavity or the skin.

Bacterial Meningitis

• Mechanism of invasion is not completely understood.

• Host defense mechanism within the CSF are often ineffective.

• Bacterial proliferation stimulates a convergence of leukocytes into the CSF.

• Meningeal and subarachnoid space inflammation release of cytokines into the CSF ( TNF, interleukin 1,6 )

Infectious agent enters Blood circulation

Meningeal vessels become

Hyperemic-Permiable

Neutrophils migrate into SAS

Induce a meningealinflammatory reaction

Fever, chillsTachycardia

Produce exudates and thickens the CSF

IICP Meningeal irritation

Hydroce-phalus Seizures

Choroid plexus/Altered BBB

Headache, vomiting,

papilledema

Macewen’s sign

+ Kernig’s /+ Brudzinski’s Sign

Interferes CSF flow

Inflammation brain parenchyma

Complication of Bacterial meningitis

immediate

Complication of Bacterial meningitis

Delayed

Seizure disorder

Focal paralysis

Subdural effusion

Hydrocephalus

Intellectual deficitsSNHL

Ataxia

Blindness

Bilateral adrenal hemorrhage

Death

Encephalitis

Encephalitis

• Inflammation of the brain parenchyma, presents as diffuse and/or focal neuropsychological dysfunction

• Most commonly a viral infection with parenchymal damage varying from mild to profound.

Etiology-encephalitis

• Arboviruses and herpes simplex virus, are the most common causes of endemic and sporadic cases of encephalitis, respectively.

• Varicella, herpes zoster and Epstein-Barr virus - cause of encephalitis in immunocompromised hosts.

• Severe and Fatal Encephalitis-Arthropod-borne viruses and HSV.

Viral replication

• Hematogenous spread to CNS• Retrograde transmission along neuronal axon• Direct invasion of the subarachnoid space

through infection in the olfactory submucosa

Vectors and Reservoirs

>> Humans are the reservoir for enteroviruses, mumps, measles, herpes simplex, and varicella viruses.

>> H. capsulatum and C. neoformans are organisms found in soil contaminated with bird droppings.

>> Cats are the definitive host for T. gondii; they acquire the parasite from eating infected rodents or other infected meat.

>> Monkeys are the reservoir for simian B virus (cercopithecine herpesvirus 1).

Vectors and Reservoirs

Modes of Transmission>> Enteroviruses: transmitted from person to

person -through ingestion of materials

contaminated by the feces of an infected person

- through exposure to infectious respiratory droplets

- indirectly via fomites>> Some causes of encephalitis, such as Listeria

sp. and T. gondii, may be acquired through consumption of contaminated food.

>> Measles and varicella viruses are transmitted from person to person through airborne route.

>> Simian B disease is transmitted to humans: - through monkey bites - exposure of naked skin or mucous

membranes to infectious monkey saliva or monkey tissue culture

Modes of Transmission

Pathophysiology Encephalitis & Meningitis

Click

Kernig’s Sign of Meningitis:

* Pathogenesis: Meningeal irritation.

Brudzinski Sign

* Pathogenesis: Meningeal irritation.

Neck Stiffness (nuchal rigidity)

* Pathogenesis: Meningeal irritation.

COMPLICATIONS

IICP

Hydrocephahus

Seizures

Diagnostic Strategies

Brain Abscess: CT Scan

Ring enhancement.Surrounding area of inflammation & edema

Hydrocephalus:

Diagnostic Strategies

Lumbar Puncture

Contraindication • Presence of infection on the skin or

soft tissues at the puncture site.• Likelihood of brain herniation.

Contraindication • Present of infection in the skin, soft

tissue at the puncture site.• Likelihood of brain herniation.

Lumbar PunctureIndication for CT scan before LP in suspected Bacterial meningitis

• Immunocompromised state

• History of Stroke

Mass lesionFocal infectionHead trauma

• Seizure occuring 7 days prior

• Abnormal level of consciousness

• Inability to answer questions or follow command

• Abnormal visual fields or paresis of gaze

• Focal weakness• Abnormal speech

CSF Analysis

Opening pressure- 50-200 mmH2O- Lateral recumbent position and sitting position may increase it several fold.- Elevated in bacterial, TB, fungal infections- Falsely elevated in tense and obese patients or when there is marked muscle contraction.

END

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Nursing Diagnoses

1. Acute pain r/t stimulation of free nerve endings.

2. Ineffective cerebral tissue perfusion r/t increased intracranial pressure.