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Make the Diagnosis: Meningitis, Adult

Prior Probability

Meningitis can occur sporadically or in outbreaks. It is impossible to come up with a single prior probability estimate for all patients with symptoms compatible with meningitis. Among patients presenting to the emergency department at a single US hospital with a clinical suspicion of meningitis who underwent LP, the prevalence of meningitis (CSF WBC ≥ 6/mL) was 27%.1 Among the patients in this study,1 the prevalence of bacterial meningitis as defined by a positive CSF culture result was 1%. The rates of meningococcal meningitis are low (approximately 1 case/100 000 persons each year;; accessed June 3, 2008).

Population for Whom Meningitis Should Be Consisered

Among immunocompetent patients, meningitis should be considered for patients presenting with combinations of findings that include fever, headache, altered mental status, neck stiffness, or photophobia.

Detecting the Likelihood of Meningitis

The most common symptoms associated with meningitis are not particularly useful when interpreted in isolation (Table 30-7).

Table 30-7.Likelihood Ratios of Headache and Nausea/Vomiting Are Not Highly Useful

Once meningitis is considered, clinicians should determine whether a patient requires cranial imaging before LP. Items from the medical history and physical examination that should be used include age greater than 60 years, immunocompromised state, history of CNS disease, seizure within 1 week of presentation, and neurologic abnormality (decreased level of consciousness, inability to answer questions and follow commands, gaze palsy, abnormal visual fields, facial palsy, abnormal motor function, and abnormal language).

Reference Standard Test

Microbiologic culture.

Original Article: Does This Adult Patient Have Acute Meningitis?

Clinical Scenarios

Case 1

A 30-year-old man presents to the emergency department with a 24-hour history of chills and a stiff neck. On clinical examination, he is afebrile and has normal mental status. He can fully flex his neck, although he complains of pain over his cervical spine when doing so. Kernig and Brudzinski signs are absent.

Case 2

A previously healthy 70-year-old woman presents to the emergency department with a 3-day history of fever, confusion, and lethargy. She is unable to cooperate with a full physical examination, but she has neck stiffness on neck flexion. The findings from a chest radiograph and urinalysis are normal.

Why Is Clinical Examination Important?


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