Headache, Diagnosis - CT Scan vs Cerebrospinal Fluid

3/11/02 (Del Rio)

Question: What is the utility of CT Scan vs. LP in the diagnosis of headache?

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Unique Identifier:11742046

Authors: Hasbun R. Abrahams J. Jekel J. Quagliarello VJ.

Institution: Department of Internal Medicine, Yale University School of Medicine, New Haven, CT, USA.

Title: Computed tomography of the head before lumbar puncture in adults with suspected meningitis. [see comments.].

Source: New England Journal of Medicine. 345(24):1727-33, 2001 Dec 13.

Abstract: BACKGROUND: In adults with suspected meningitis clinicians routinely order computed tomography (CT) of the head before performing a lumbar puncture. METHODS: We prospectively studied 301 adults with suspected meningitis to determine whether clinical characteristics that were present before CT of the head was performed could be used to identify patients who were unlikely to have abnormalities on CT. The Modified National Institutes of Health Stroke Scale was used to identify neurologic abnormalities. RESULTS: Of the 301 patients with suspected meningitis, 235 (78 percent) underwent CT of the head before undergoing lumbar puncture. In 56 of the 235 patients (24 percent), the results of CT were abnormal; 11 patients (5 percent) had evidence of a mass effect. The clinical features at base line that were associated with an abnormal finding on CT of the head were an age of at least 60 years, immunocompromise, a history of central nervous system disease, and a history of seizure within one week before presentation, as well as the following neurologic abnormalities: an abnormal level of consciousness, an inability to answer two consecutive questions correctly or to follow two consecutive commands, gaze palsy, abnormal visual fields, facial palsy, arm drift, leg drift, and abnormal language (e.g., aphasia). None of these features were present at base line in 96 of the 235 patients who underwent CT scanning of the head (41 percent). The CT scan was normal in 93 of these 96 patients, yielding a negative predictive value of 97 percent. Of the three misclassified patients, only one had a mild mass effect on CT, and all three subsequently underwent lumbar puncture, with no evidence of brain herniation one week later. CONCLUSIONS: In adults with suspected meningitis, clinical features can be used to identify those who are unlikely to have abnormal findings on CT of the head.

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Unique Identifier:10597758

Authors: Gopal AK. Whitehouse JD. Simel DL. Corey GR.

Institution: Department of Medicine, Duke University, Durham, NC, USA. agopal@u.washington.edu

Title: Cranial computed tomography before lumbar puncture: a prospective clinical evaluation. [erratum appears in Arch Intern Med 2000 Nov 27;160(21):3223.].

Source: Archives of Internal Medicine. 159(22):2681-5, 1999 Dec 13-27.

Abstract: OBJECTIVE: To prospectively identify which patients can safely undergo lumbar puncture (LP) without screening cranial computed tomography (CT). METHODS: Emergency department physicians examined patients before CT. Examiners recorded the presence or absence of 10 clinical findings and answered 8 additional questions. The criterion standard was noncontrast cranial CT interpreted by staff radiologists. Clinical findings were prospectively compared with those of CT. RESULTS: One hundred thirteen consecutive adults with the urgent need for LP (median age, 42 years) were studied. Fifteen percent of patients meeting entrance criteria had new CT-documented lesions, with 2.7% having lesions that contraindicated LP. Sensitivity, specificity, and likelihood ratios (LRs) were measured for the clinical findings. Three statistically significant predictors of new intracranial lesions were identified: altered mentation (positive LR, 2.2; 95% confidence interval [CI], 1.5-3.2), focal neurologic examination (positive LR, 4.3; 95% CI, 1.9-10), and papilledema (positive LR, 11.1; 95% CI, 1.1-115). No single item adequately predicted the absence of CT abnormalities, but the clinical screening items in aggregate significantly predicted the results (negative LR, 0; upper 95% confidence limit, 0.6). The overall clinical impression had the highest predictive value in identifying patients with CT-defined contraindications to LP (positive LR, 18.8; 95% CI, 4.8-43). CONCLUSIONS: Because of the low prevalence of lesions that contraindicate LP, screening cranial CT solely to establish the safety of performing an LP typically provides limited additional information. Physicians can use their overall clinical impression and 3 clinical predictors to identify patients with the greatest risk of having intracranial lesions that may contraindicate LP.

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Unique Identifier:7989684

Authors: Baker ND. Kharazi H. Laurent L. Walker AT. Williamson DS. Weissman BN. Zamani A. Sanchez R.

Institution: Department of Radiology, Brigham and Women's Hospital, Boston, Massachusetts 02115.

Title: The efficacy of routine head computed tomography (CT scan) prior to lumbar puncture in the emergency department. [see comments.].

Source: Journal of Emergency Medicine. 12(5):597-601, 1994 Sep-Oct.

Abstract: The efficacy of using unenhanced head computed tomography (CT scans) as a routine screening procedure prior to lumbar puncture in the emergency department is studied retrospectively by comparing opening pressure during lumbar puncture to CT scan diagnosis in 42 patients. No correlation was found between CT scan findings and opening pressure.

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Unique Identifier:8448711

Authors: Archer BD.

Institution: Department of Radiology, McMaster University Medical Centre, Hamilton, ON.

Title: Computed tomography before lumbar puncture in acute meningitis: a review of the risks and benefits. [see comments.]. [Review] [20 refs]

Source: Cmaj (Canadian Medical Association Journal). 148(6):961-5, 1993 Mar 15.

Abstract: OBJECTIVE: To determine the indications, if any, for routine computed tomography (CT) of the brain before lumbar puncture in the management of acute meningitis. DATA SOURCES: Original research papers, reviews and editorials published in English from 1965 to 1991 were retrieved from MEDLINE. The bibliographies of these articles and of numerous standard texts were examined for pertinent references. A survey of local neurologists was conducted, and legal opinion was sought from the Canadian Medical Protective Association. DATA EXTRACTION: There were no studies directly assessing the risks of lumbar puncture in meningitis; however, all sources were culled for other pertinent information. RESULTS: No cases could be found of patients with acute meningitis deteriorating as a result of lumbar puncture. The neurologic consensus refuted the need for CT in typical acute meningitis. All sources stressed speedy lumbar puncture and the early institution of appropriate antibiotic therapy to minimize the severity of the illness and the risk of death. CONCLUSIONS: (a) There is no evidence to recommend CT of the brain before lumbar puncture in acute meningitis unless the patient shows atypical features, (b) for patients with papilledema the risks associated with lumbar puncture are 10 to 20 times lower than the risks associated with acute bacterial meningitis alone, (c) CT may be necessary if there is no prompt response to therapy for meningitis or if complications are suspected, (d) the inability to visualize the optic fundi because of cataracts or senile miosis is not an indication for CT and (e) there are no Canadian legal precedents suggesting liability if physicians fail to perform CT in cases of meningitis. [References: 20] CAS Registry/EC Number 0 (Antibiotics).