Diseases That Mimic Analysis Maurice

Meningitis

of 650 Lumbar Punctures

Levy, MD,*

E.

Wong, MD,†

D.

Fried, MD*

A retrospective review of charts for 650 children who had lumbar puncture for suspected meningitis was undertaken to determine the characteristics of patients with and without meningitis, identify other conditions suggesting meningitis, and evaluate the predictive value of signs and symptoms of meningitis. The incidence of positive lumbar punctures increased with patient age. Younger infants did not present with classical features of meningitis. Bulging fontanel, lethargy, and irritability were nonspecific symptoms. Vomiting and headache, although not specific, proved to be more sensitive indicators of meningeal infection. Most patients with meningitis (75%) had at least one sign of meningeal irritation, but so did 25% of patients without meningitis. Brudzinski’s sign was not specific. In contrast, nuchal rigidity and Kernig’s sign had high predictive value. Up to age five, the diseases most often suggesting meningitis were right-sided pneumonia, gastroenteritis, otitis, tonsillitis, exanthema subitum, and urinary tract infections. Of 171 patients with febrile convulsion, one (0.5% ) had bacterial meningitis and four had aseptic meningitis.

BACTERIAL

MENINGITIS in childhood is a in which the prognosis is infection life-threatening more dependent upon early diagnosis and prompt intensive treatment than perhaps in any other infectious disease. Diagnosis is complicated, however, by the ambiguity of symptoms, such as fever, headache, and vomiting, which suggest meningeal or intracranial pathology but are also common to many other conditions. Furthermore, meningeal signs may be absent in infants, elderly, and immunosuppressed patients with meningitis.1,2 Consequently, we frequently have to decide whether a particular patient From the *Department of Pediatrics, Edith Wolfson Hospital, Houlon, Israel, and the †Division of Infectious Disease, The Hospital for Sick Children and the Department of Paediatrics, University of Toronto, Toronto, Canada. Correspondence to: Maurice Levy, MD, Division of Clinical Pharmacology, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario, Canada M5G 1X8. Dr. Levy is presently in the Division of Clinical Pharmacology at The Hospital for Sick Children, Toronto, Canada. Received for publication October 1989, revised November 1989, and accepted January 1990.

has sufficient

signs of meningitis to warrant a lumbar puncture (LP). Although the LP is the most valuable procedure for establishing the diagnosis and is performed whenever the disease is suspected, it does involve some risk. Ideally, we would avoid missing any case of meningitis while performing no diagnostic LPs on patients without meningitis. Although the value of LP in diagnosing meningitis is established, the literature has not addressed the question of specific indications for this procedure in suspected meningitis.3,4 Most reviews and textbooks emphasize the need for a high index of suspicion and the importance of performing a LP in any child suspected of having meningitis (unless there are specific contraindications to this procedure) but give no data on the reliability of the signs commonly associated with the disease.’ We reviewed the charts of 650 children who had LP for suspected meningitis to identify the percentage of normal LPs in different age groups, the diseases that most often simulated meningitis in these children, the relevant signs and symptoms observed

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meningitis, and determine the signs and/or sympthat alone or in combination have a high predictive value for meningitis.

years of age. These age groupings were selected because of the reported variable incidence of clinical

Materials and Methods

Results

We reviewed the charts of 650 children who had LP for a presumed diagnosis of meningitis in the

General Data

in

toms

of Edith Wolfson Hospital, to 1982. The decision to LPs was a made board-certified or eligiby perform ble pediatrician, one of whom was available 24 hours a day, 7 days a week. The presenting signs and symptoms, results of the LP, and the diagnosis at discharge were documented. The following symptoms and signs were also recorded: fever, febrile convulsion, convulsion without fever, restlessness, lethargy, vomiting, headache, neck stiffness, Kernig’s sign, Brudzinski’s sign, and bulging fontanel. LP was performed in all children presenting with a first episode of seizure and fever. The patients were categorized according to their CSF findings as follows: normal findings, findings compatible with bacterial meningitis, and findings suggestive of aseptic meningitis. Children with bacterial meningitis had high cell counts (predominantly polymorphonuclear cells), low or normal sugar levels, and elevated protein. In most such instances bacteria were recovered from the CSF culture. All of these children were treated with antibiotics for meningitis. The children with viral meningitis had moderately elevated cell counts (predominantly mononuclear cells), normal glucose, and slightly elevated protein. In 39% of such cases, viruses were isolated from the CSF. Patients were divided into groups according to age as follows: group 1, 0-8 weeks of life; group 2, 8 weeks to 24 months; group 3, 2-5 years; and group 4, 5-12

pediatric department

Houlon, Israel from 1977

TABLE 1. Incidence

*

CSF,

i

findings in young patients with meningitis. 6-11

Mean CSF laboratory findings in patients with bacterial meningitis were as follows: CSF WBC count/

mm’, 4,500 ± 3,000 (range, 250-10,500); glucose, 27.0 ± 7 mg/dl (range, 0-80); protein, 140 ± 40 mg/dl (range, 30-250 mg/dl). In all age groups, hemophilus influenza type b was isolated most often, followed by pneumococcus, meningococcus, group B streptococcus, and Salmonella group D.

laboratory findings in the cases of viral menfollows: CSF WBC count/mm3, 550 ingitis ± 450 (range, 10-7,500); glucose, 55 ± 15 mg/dl (range, 25-90 mg/dl); protein, 57 ± 17 mg/dl (range, 20-160 mg/dl). Responsible agents were Mean

were as

echovirus types 9, 4, 7, 14, coxsackie Ag, B2 , B5 , and mumps virus. Of the 90 LPs performed routinely in children between 2 months and 5 years of age because of a first episode of seizure and fever, only one (from a 10-month-old infant) was positive for bacterial meningitis. Other illnesses associated with febrile convulsions were otitis media, pharyngotonsillitis, shigellosis, herpangina, bronchopneumonia, and urinary tract infection. Incidence of Normal and Abnormal CSF

Findings

Table 1 shows the distribution of meningitis according to age groups and the incidence of negative LP (i.e., normal CSF). Of 58 newborns who had LPs, 48 (82.7%) had normal CSF findings. This high fre-

of Meningitis and Normal CSF *-Findings in 650 Lumbar Punctures

Cerebrospinal fluid.

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Downloaded from cpj.sagepub.com at UNIVERSITY OF WATERLOO on March 13, 2015

Downloaded from cpj.sagepub.com at UNIVERSITY OF WATERLOO on March 13, 2015

quency of negative LPs is due to the large number of LPs performed in babies who present with fever but without other specific findings. The incidence of negative LPs (65%) was lower in group 2 than in group 1; however, it was still relatively high because in our setting LPs were performed routinely in children with a first episode of convulsion with fever. In group 3, I I5 (53%) of 217 children had normal LPs. Diseases that Mimic

Meningitis

Table 2 shows diseases that were found to mimic and their prevalence in the age groups studied. Pneumonia simulated meningitis in all age groups studied. It involved the right side, mainly the right middle and upper lobes. Clinically, patients with pneumonia were described as looking unwell, being septic with fever, having headache, and showing at least one meningeal sign, usually Brudzinski’s sign. An encephalopathic picture was also observed as was respiratory distress manifested by grunting and absent pulmonary findings. Some patients presented with opisthotonus or positive Kernig’s or Brudzinski’s sign. Pleural irritation, mainly of the right upper lobe, elicited meningismus, which was distinguished from meningitis by examination of the CSF.

meningitis

A significant number of patients with negative LPs had gastroenteritis, usually shigellosis and salmonellosis. They presented with encephalopathic, toxic, or septic appearances associated with high fever with or without convulsions. Associated headache, Brudzinski’s sign, and nuchal rigidity were not uncommon. Initially, shigellosis was not considered in most of these patients because diarrhea did not develop until later. Patients who ultimately proved to have otitis media had LP primarily because of fever, irritability, and absent or ambiguous ear findings. The disease

usually accompanied upper respiratory infection (URI), and the meningeal signs seen in these patients may have been the result of nuchal muscle spasm associated with cervical lymphadenitis. Patients who were found to have exanthema subitum had LP primarily because of fever, lethargy, irritability, vomiting, and convulsions. LPs were also performed in patients who proved to have other conditions such as pharyngotonsillitis, URI, and herpangina. In most of these cases, no clear physical findings were associated with the meningeal signs, but high fever, headache, and vomiting were common.

Urinary tract infections presented with nonspecific signs and symptoms.

TABLE 2. Diseases That Mimic Meningitis in 650 Lumbar Punctures

URI, upper respiratory

tract

infection; GIT, gastrointestinal; LP, lumbar puncture.

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and Symptoms in Patients With and Without Meningitis

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Diseases that mimic meningitis. Analysis of 650 lumbar punctures.

A retrospective review of charts for 650 children who had lumbar puncture for suspected meningitis was undertaken to determine the characteristics of ...
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