Definition -it is an inflammation of the lining around the brain and spinal cord caused by bacteria /viruses.
Meningitis is classified as
Aseptic- the cause is viral or secondary to lymphoma , leukemia, HIV
Septic – it is caused by bacteria
· Bacteria : streptococcus pneumoniae and Neisseria meningitides are responsible for 80% of cases of meningitis in adults.
· Neisseria meningitides infection are most likely to occur in dense community groups such as college campuses and military installations. The peak incidence is in the winter and early spring
Risk factors for bacterial meningitis
· Tobacco use
· Viral upper respiratory infections
· Otitis media and mastoiditis — because bacteria can cross the epithelial membrane and enter the subarachnoid space.
· People with immune deficiency
· Meningeal infections generally originate in one of two ways: through the bloodstream because of other infections or by direct spread, such as might occur after a traumatic injury to the facial bones or secondary to invasive procedures.
· N. meningitides concentrates in the nasopharynx and is transmitted by secretion or aerosol contamination.
· Bacterial or meningococcal meningitis also occurs as an opportunistic infection in patients with acquired immunodeficiency syndrome (AIDS) and as a complication of Lyme disease.
· Once the causative organism enters the bloodstream, it crosses the blood-brain barrier and proliferates in the cerebrospinal fluid (CSF).
· The host immune response stimulates the release of cell wall fragments and lipopolysaccharides, facilitating inflammation of the subarachnoid and pia mater.
· Because the cranial vault contains little room for expansion, the inflammation may cause increased intracranial pressure (ICP). CSF circulates through the subarachnoid space, where inflammatory cellular materials from the affected meningeal tissue enter and accumulate.
· The prognosis for bacterial meningitis depends on the causative organism, the severity of the infection and illness, and the timeliness of treatment.
· Acute fulminant presentation may include adrenal damage, circulatory collapse, and widespread hemorrhages (Waterhouse-Friderichsen syndrome).
· This syndrome is the result of endothelial damage and vascular necrosis caused by the bacteria. Complications include visual impairment, deafness, seizures, paralysis, hydrocephalus, and septic shock.
· Headache and fever are frequently the initial symptoms
· Fever tends to remain high throughout the course of illness
· The headache is usually either steady or throbbing and very severe as a result of meningeal irritation
· Neck mobility —a stiff and painful neck (nuchal rigidity) can be early sign and any attempts at flexion of the head are difficult because of spasm in the muscles of the neck.
· Positive kernig’s Sign — when the patient is lying with the thigh flexed on the abdomen, the leg cannot be completely extended.
· Positive brudzinski’s sign — when the patients neck is flexed (after ruling out cervical trauma or injury), flexion of the knees and hips is produced; when the lower extremity of one side is passively flexed, a similar movement is seen in the opposite extremity. Brudzinkis sign is a more sensitive indicator of meningeal irritation than kernigs sign.
· Photophobia: (extreme sensitive light) this finding is common, although the cause is unclear
· A rash can be a striking feature of N. meningitidis infection, occurring in about half of patients with this type of meningitis. Skin lesions develop, ranging from a petechial rash with purpuric lesions to large areas of ecchymosis.
· Disorientation and memory impairment are common early in the course of the illness. The changes depend on the severity of the infection as well as the individual response to the physiologic processes. Behavioral manifestations are also common. As the illness progresses, lethargy, unresponsiveness, and coma may develop.
· Seizures can occur and are the result of areas of irritability in the brain. ICP increases secondary to diffuse brain swelling or hydrocephalus
· The initial signs of increased ICP include decreased level of consciousness and focal motor deficits. If ICP is not controlled, the uncus of the temporal lobe may herniate through the tentorium, causing pressure on the brain stem. Brain stem herniation is a life-threatening event that causes cranial nerve dysfunction and depresses the centers of vital functions, such as the medulla.
· Clinical manifestations suggests meningitis
· A computed tomography (CT) scan or magnetic resonance imaging (MRI) scan is used to detect a shift in brain contents (which may lead to herniation) prior to a lumbar puncture
· Bacterial culture and Gram staining of CSF and blood are key diagnostic tests. CSF studies demonstrate low glucose, high protein levels, and high white blood cell count. Gram staining allows for rapid identification of the causative bacteria and initiation of appropriate antibiotic therapy.
· Meningococcal conjugated vaccine should be given to adolescents entering high school and to college freshmen living in dormitories.
· People in close contact with patients with meningococcal meningitis should be treated with antimicrobial chemoprophylaxis using rifampin (Rifadin), ciprofloxacin hydrochloride (Cipro), or ceftriaxone sodium (Rocephin).
· Therapy should be started within 24 hours after exposure because a delay in the initiation of therapy limits the effectiveness of the prophylaxis. Vaccination should also be considered as an adjunct to antibiotic chemoprophylaxis for anyone living with a person who develops meningococcal infection.
· Vaccination against H. influenza and S. Pneumonia should be encouraged for children and at-risk adults.
· Successful outcomes depend on the early administration of an antibiotic that crosses the blood-brain barrier into the subarachnoid space in sufficient concentration to halt the multiplication of bacteria.
· Vancomycin hydrochloride in combination with one of the cephalosporin (eg, ceftriaxone sodium, cefotaxime sodium) is administered intravenously (IV)
· Dexamethasone (Decadron) has been shown to be beneficial as adjunct therapy in the treatment of acute bacterial meningitis and in pneumococcal meningitis if it is administered 15 to 20 minutes before the first dose of antibiotic and every 6 hours for the next 4 days.
· Dehydration and shock are treated with fluid volume expanders.
· Seizures, which may occur early in the course of the disease, are controlled with phenytoin (Dilantin).
· Increased ICP is treated as necessary
· Neurologic status and vital signs are continually assessed.
· Pulse oximetry and arterial blood gas values are used to quickly identify the need for respiratory support if increasing ICP compromises the brain stem.
· Insertion of a cuffed endotracheal tube (or tracheotomy) and mechanical ventilation may be necessary to maintain adequate tissue oxygenation.
· Blood pressure is assessed for incipient shock , which precedes cardiac or respiratory failure.
· Rapid IV fluid replacement may be prescribed , but care is to be taken to prevent fluid overload
· Fever also increases the workload of the heart and cerebral metabolism .ICP will increase in response to increased cerebral metabolic demands. Therefore, measures are taken to reduce body temperature as quickly as possible.
· Protecting the patient from injury secondary to seizure activity or altered LOC
· Monitoring daily body weight; serum electrolytes; and urine volume, specific gravity, and osmolality, especially if syndrome of inappropriate antidiuretic hormone (SIADH) is suspected
· Preventing complications associated with immobility, such as pressure ulcers and pneumonia
· Instituting infection control precautions until 24 hours after initiation of antibiotic therapy (oral and nasal discharge is considered infectious)