Learn how to distinguish between these common central nervous system infections and respond appropriately.

MENINGITIS AND ENCEPHALITIS are two of the most common central nervous system (CNS) inflammations you'll encounter when caring for hospitalized patients. These inflammations can be the reason the patient is hospitalized or can develop during hospitalization, and both can affect patients of any age. Meningitis and encephalitis can be fatal if not diagnosed and treated promptly; even with treatment, some patients suffer CNS damage and serious permanent neurologic problems.

In this article, we'll explain how to assess a patient with acute meningitis or encephalitis and discuss appropriate nursing interventions, which focus on administering medications, monitoring neurologic status, and providing supportive care for patients and their families. Let's start with some facts about meningitis.

About meningitis

Meningitis is an inflammation of the meninges, the lining of the brain and spinal cord (see Protecting the CNS). It's usually caused by a primary viral or bacterial infection, but it also can develop from a fungal infection or be secondary to other causes, such as neurosurgery, penetrating head trauma, and facial fractures that cause cerebrospinal fluid (CSF) leak.

Determining the underlying cause of meningitis is crucial to treating it correctly. Because viral and bacterial meningitis are the most common types, we'll focus on them here. (See The many faces of meningitis for more on the other types.)

Viral (aseptic) meningitis, more common than the bacterial type, is generally less severe and typically self-limiting. Treatment focuses on symptoms, although they may resolve without treatment in as few as 10 days. About 90% of viral meningitis cases in the United States are caused by enteroviruses, which also cause stomach flu. Other potential culprits include varicella zoster, influenza, mumps, HIV, and herpes simplex virus type 2.

Bacterial meningitis, although rare, can be rapidly fatal. It can develop when bacteria invade the meninges directly or when bacteria travel through the bloodstream to the brain from the site of another infection (such as sinusitis, mastoiditis, and otitis media). Patients who are immunocompromised and travelers to foreign countries where the disease is endemic are at greater risk for all types of meningitis. In the United States, the leading causes of bacterial meningitis are Streptococcus pneumoniae and Neisseria meningitidis.

* Pneumococcal meningitis (caused by S. pneumoniae) is the most common and most serious form of bacterial meningitis. Many patients who've had pneumococcal meningitis suffer neurologic damage ranging from deafness to severe brain damage.

* Meningococcal meningitis (caused by N. meningitidis) is spread by contact with infectious secretions from the respiratory tract and throat. Although it can affect patients of all ages, the very old and very young are especially vulnerable. So are teens and college students living in dormitories because prolonged close contact, including sharing food or utensils, encourages the disease to spread.

Signs and symptoms of meningitis are similar regardless of whether it's viral or bacterial in origin, although symptoms of viral meningitis may be milder. Inflammation of the meninges causes neck stiffness and headache, the two most frequently reported symptoms of meningitis. The patient also may have nausea, vomiting, fever, photophobia (light sensitivity), phonophobia (sound sensitivity), confusion, sleepiness, and in severe cases, seizures. Some forms of meningitis cause a nonpruritic rash.

These signs and symptoms develop over several hours or up to 2 days, and often are mistaken for a severe cold or flulike illness. As a result, patients may not seek medical attention immediately. Many patients notice some degree of fatigue for a week or two beforehand.

Neonates and infants may not exhibit classic signs and symptoms, but are extremely irritable or lethargic and become more distressed when a parent tries to console them.

About encephalitis

Encephalitis is an inflammation of the brain itself. Most cases in the United States are caused by enteroviruses, herpes simplex virus types 1 and 2, rabies virus, or arboviruses transmitted by infected animals (such as a tick or mosquito). Lyme disease also can cause encephalitis.

Although various medical conditions can cause noninfectious encephalitis, most cases are viral. In this article, we'll focus on the four forms of mosquito-transmitted viral encephalitis found in the United States:

* Equine encephalitis, which affects humans only rarely, can cause sudden fever and an increasingly severe headache. Severe infection can cause coma and death.

* La Crosse encephalitis, which accounts for about 100 cases/year, occurs most often in the midwestern states and in children under age 16. In severe cases, seizures, coma, and permanent neurologic damage may occur.

* St. Louis encephalitis occurs nationwide but is more common in temperate areas; older adults are at most risk for severe disease or death. Severe cases can cause confusion, tremors, convulsions, and coma.

If you're assessing a patient with suspicious signs and symptoms, start by taking a history, focusing on possible mosquito exposure. Perform a physical assessment, focusing on the neurologic system.

Your neurologic assessment for an adult should include the Mini-Mental State Examination to screen for cognitive dysfunction. Also assess his level of agitation to help plan patient safety, including fall prevention.

You can perform two simple tests to help determine if the patient has meningeal inflammation. Both are done with the patient lying supine on the bed. To test for Kernig's sign, flex one of the patient's legs at both his hip and knee, then straighten his knee. Pain and increased resistance to knee extension are a positive Kernig's sign and suggest meningeal irritation. To test for Brudzinski's sign, first make sure the patient has no injury to the cervical spine. Then place your hands behind his head and flex his neck forward until his chin touches his chest (if possible). As you flex his neck, watch his hips and knees. Normally, they remain relaxed and motionless. Involuntary flexion of the hips and knees is a positive Brudzinski's sign, suggesting meningeal irritation.

To evaluate CSF, prepare the patient for a lumbar puncture (also called a spinal tap). Meningitis typically causes a low glucose count and elevated white blood cell count. In bacterial meningitis, the CSF protein concentration is elevated. A sample of CSF also should be sent for culture and sensitivity to identify the causative organism, if it's bacterial, and to guide treatment. Also obtain blood specimens for electrolyte values, complete blood cell count, blood cultures, and possibly a polymerase chain reaction analysis to check for certain viruses.

The patient may have a computed tomography scan or magnetic resonance imaging of his head and sinuses to detect inflammation and certain viral infections and to rule out other possible causes of his signs and symptoms. An electroencephalogram also may be performed to rule out seizure disorders.

Treating meningitis and encephalitis

If the meningitis turns out to be viral in origin, the health care provider will discontinue the antibiotics and may order an antiviral drug such as acyclovir or ganciclovir.

For both types of meningitis, supportive treatment may include I.V. fluids to replace losses from diaphoresis and vomiting. Institute seizure precautions and administer acetaminophen, as prescribed, to manage fever and pain associated with headache or neck stiffness. The health care provider may prescribe antiepileptics if the patient has seizures; she may also order these drugs prophylactically if the patient has severe meningeal edema. Mannitol may be used to reduce intracranial hypertension, a potential complication of meningitis and encephalitis.

If she orders antiemetics to treat nausea and vomiting, monitor the patient for excess sedation. If his sinuses are infected, he may need to have them drained.

Patients with severe encephalitis may need physical, speech, and occupational therapy once the acute illness is under control.

Planning routine nursing care

For any patient with meningitis or encephalitis, perform frequent vital signs and neurologic assessments for signs of disease progression, such as decreased level of consciousness. Assess mental status, muscle strength, headache severity, and pupillary reactions. Maintain a patent airway, suctioning the patient as needed and positioning him to encourage drainage of oral and nasal secretions. Monitor his oxygenation and administer supplemental oxygen if indicated. Assess him for cyanosis and dyspnea and monitor his arterial blood gas analysis results.

Many patients experience photophobia or phonophobia. Keeping your patient's room quiet and darkened can make him more comfortable and reduce his agitation. Group your nursing interventions to minimize the stress of repeated procedures, and limit visitors and other sources of stimulation.

Assess the patient's ability to swallow. Advocate for a swallow study, if indicated, as well as for a nutritional consult; he may need enteral or parenteral nutrition.

Depending on the patient's level of consciousness, he may need an indwelling urinary catheter for accurate intake and output monitoring. Provide meticulous skin care to prevent skin breakdown. If he's extremely diaphoretic, change the bed linens frequently to prevent skin irritation. While he's on bed rest, apply graduated compression stockings to help prevent venous thromboembolism.

Take safety precautions such as raising the side rails and keeping the bed in low position when the patient is alone, and observing him frequently. Make sure any catheters are secured so they can't be dislodged by patient movement.

Provide emotional support and education for the patient and his family and facilitate communication between them and the health care team, as the recovery period may be prolonged. Families may need a lot of teaching and support to understand the changes taking place in their loved one. Arrange for a social service consult early in the hospitalization. For more patient pointers, see Help your patient prevent bacterial meningitis.

Preventive steps

Vaccines are available against pneumonia, Haemophilus influenzae type b (Hib), pneumococcal meningitis, and other bacteria that can lead to meningococcal meningitis. However, no vaccines are available for encephalitis.

Meticulous hand hygiene also can reduce risk: Teach patients to wash their hands before and after exposure to someone who may be infected with meningitis or encephalitis. Thorough hand washing after using the bathroom also reduces exposure to many of the enteroviruses that can cause viral meningitis.

Community mosquito control programs also can help prevent meningitis and encephalitis. Teach patients to use insect repellent when outdoors and to keep their properties free from standing water, which is where mosquitoes lay eggs.

On the mend

Caring for a patient with meningitis or encephalitis can be challenging, but by understanding these two diseases, you can help your patient and his family on the road to recovery.

Protecting the CNS

The meninges are made up of the dura mater, arachnoid, and pia mater, as shown in this section of the superior sagittal sinus of the brain and the section of the spinal cord, below.

The many faces of meningitis

In addition to viral meningitis and the forms caused by S. pneumoniae and N. meningitidis, the National Institute of Neurological Disorders and Stroke describes these types of meningitis:

* Hib meningitis, the leading cause of bacterial meningitis in the United States before 1990, when routine immunization of infants began

* Listeria monocytogenes meningitis, which can cross the placenta, killing a fetus

* Escherichia coli meningitis, which is common in older adults and in newborns infected during vaginal delivery

* Mycobacterium tuberculosis meningitis, a rare form caused by the tuberculosis bacterium attacking the meninges

* fungal meningitis caused by

Share these pointers with your patient:

* Wash your hands often with soap and water.

* Don't share food, drinking glasses, eating utensils, tissues, towels, lipstick, or cigarettes.

* Keep your immune system healthy by eating a well-balanced diet rich in fruits and vegetables, getting enough sleep and exercise, and avoiding tobacco, drugs, and alcohol.

* If you've been exposed to someone with meningitis, ask your health care provider if you need antibiotics.

* If you're traveling to a place where meningitis is common, ask your health care provider if you need a vaccine.

Bader MK, Littlejohns LR. AANN Core Curriculum for Neuroscience Nursing, 4th edition. W.B. Saunders Co., 2004.