The role of cranial CT in the investigation of meningitis

OBJECTIVE To assess the usage of cranial computed tomography (CT) in patients admitted with meningitis. DESIGN Retrospective study. SETTING Heart of England NHS foundation trust, a teaching hospital in the West Midlands. PARTICIPANTS Two groups of adult patients admitted with meningitis between April 2001 and September 2004 and from September 2006 until September 2009. MAIN OUTCOME MEASURES The numbers of patients having cranial CT and lumbar puncture and whether any complications had arisen following lumbar puncture. The appropriateness of the CT request according to local criteria. RESULTS A total of 111 patients were admitted in the initial time period and 47 patients in the second time period. In the first group, 67 patients underwent CT (61%), compared with 36 patients (80%) in the second group. There were eight abnormal scans (12%) in the initial group including three patients with radiological features of cerebral oedema. Of these patients, one underwent lumbar puncture and had no neurological sequelae. In the second group, there were five abnormal scans (14%) with one presenting a contraindication for lumbar puncture due to mild ventricular dilatation. A lumbar puncture was performed in this patient without complication. All patients with abnormal scans had clinical features to suggest raised intracranial pressure. CT scan requests were considered inappropriate in 26% of patients in the initial study period and 56% of patients in the second study period. CONCLUSION More patients with meningitis are undergoing CT and the number of inappropriate requests are increasing. There are few abnormal CT scans presenting a contraindication for lumbar puncture and the majority of these patients usually have clinical signs to suggest raised intracranial pressure.