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Key Features

Essentials of Diagnosis

  • Fever, headache, vomiting, delirium, convulsions

  • Petechial rash of skin and mucous membranes

  • Neck and back stiffness

  • Purulent spinal fluid with gram-negative intracellular and extracellular diplococci

  • Culture of cerebrospinal fluid, blood, or petechial aspiration confirms the diagnosis

General Considerations

  • Caused by Neisseria meningitidis of groups A, B, C, Y, W-135, and others

  • Infection is transmitted by droplets

  • The clinical illness may take the form of meningococcemia (a fulminant form of septicemia) without meningitis, meningococcemia with meningitis, or predominantly meningitis

  • Chronic recurrent meningococcemia with fever, rash, and arthritis can occur, particularly in those with terminal complement deficiencies

Demographics

  • College freshmen—particularly those living in dormitories—have been shown to have a modestly increased risk of invasive meningococcal disease

  • Asplenic patients are also at risk

Clinical Findings

Symptoms and Signs

  • High fever, chills, nausea and vomiting, and headache as well as back, abdominal, and extremity pains are typical

  • In severe cases, rapidly developing confusion, delirium, seizures, and coma occur

  • Nuchal and back rigidity are typical

  • A petechial rash often first appearing in the lower extremities and at pressure points is found in most cases

  • Petechiae may vary from pinhead sized to large ecchymoses or even areas of skin gangrene that may later slough

Differential Diagnosis

  • Meningitis due to other causes, eg, pneumococcus, Listeria, aseptic

  • Subarachnoid hemorrhage

  • Encephalitis

  • Petechial rash due to

    • Gonococcemia

    • Infective endocarditis

    • Thrombotic thrombocytopenic purpura

    • Rocky Mountain spotted fever

    • Viral exanthem

    • Rickettsial or echovirus infection

    • Other bacterial infections (eg, staphylococcal infections, scarlet fever)

  • "Neighborhood reaction" causing abnormal cerebrospinal fluid, such as

    • Brain abscess

    • Epidural abscess

    • Vertebral osteomyelitis

    • Mastoiditis

    • Sinusitis

    • Brain tumor

  • Dural sinus thrombosis

  • Noninfectious meningeal irritation

    • Carcinomatous meningitis

    • Sarcoidosis

    • Systemic lupus erythematosus

    • Drugs (eg, nonsteroidal anti-inflammatory drugs, trimethoprim-sulfamethoxazole)

    • Pneumonia

    • Shigellosis

Diagnosis

Laboratory Tests

  • The organism is usually found by smear or culture of the cerebrospinal fluid, oropharynx, blood, or aspirated petechiae

  • Prothrombin time and partial thromboplastin time are prolonged, fibrin dimers are elevated, fibrinogen is low, and the platelet count is depressed if disseminated intravascular coagulation is present

CEREBROSPINAL FLUID ANALYSIS

  • See Table 30–1

  • Typically, a cloudy or purulent fluid, with elevated pressure, increased protein, and decreased glucose content

  • Usually contains more than 1000 cells/mcL, with polymorphonuclear cells predominating and containing gram-negative intracellular diplococci

  • The absence of organisms in a Gram stained smear does not rule out the diagnosis

  • The capsular polysaccharide can often be demonstrated in cerebrospinal fluid or urine by latex agglutination; this is especially useful in partially treated patients, though sensitivity is only 60–80%

Table 30–1.Typical cerebrospinal fluid findings in various central nervous system diseases.

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