Book contents
- Frontmatter
- Contents
- List of contributors
- List of abbreviations
- Preface
- Section 1 Bilateral Predominantly Symmetric Abnormalities
- Section 2 Sellar, Perisellar and Midline Lesions
- Section 3 Parenchymal Defects or Abnormal Volume
- Section 4 Abnormalities Without Significant Mass Effect
- 97 Dural Venous Sinus Thrombosis
- 98 Dural Arteriovenous Fistula
- 99 Subarachnoid Hemorrhage
- 100 Laminar Necrosis
- 101 Neurocutaneous Melanosis
- 102 Superficial Siderosis
- 103 Polymicrogyria
- 104 Seizure-Related Changes (Peri-Ictal MRI Abnormalities)
- 105 Embolic Infarcts
- 106 Focal Cortical Dysplasia
- 107 Tuberous Sclerosis Complex
- 108 Dysembroplastic Neuroepithelial Tumor (DNT, DNET)
- 109 Nonketotic Hyperglycemia With Hemichorea–Hemiballismus
- 110 Hyperdensity Following Endovascular Intervention
- 111 Early (Hyperacute) Infarct
- 112 Acute Disseminated Encephalomyelitis (ADEM)
- 113 Susac Syndrome
- 114 Diffuse Axonal Injury
- 115 Multiple Sclerosis
- 116 Progressive Multifocal Leukoencephalopathy (PML)
- 117 Nodular Heterotopia
- 118 Neurosarcoidosis
- 119 Meningeal Carcinomatosis
- 120 Meningitis (Infectious)
- 121 Perineural Tumor Spread
- 122 Moyamoya
- 123 Central Nervous System Vasculitis
- 124 Subacute Infarct
- 125 Active Multiple Sclerosis
- 126 Capillary Telangiectasia
- 127 Developmental Venous Anomaly
- 128 Immune Reconstitution Inflammatory Syndrome (IRIS)
- 129 Ventriculitis
- Section 5 Primarily Extra-Axial Focal Space-Occupying Lesions
- Section 6 Primarily Intra-Axial Masses
- Section 7 Intracranial Calcifications
- Index
- References
120 - Meningitis (Infectious)
from Section 4 - Abnormalities Without Significant Mass Effect
Published online by Cambridge University Press: 05 August 2013
- Frontmatter
- Contents
- List of contributors
- List of abbreviations
- Preface
- Section 1 Bilateral Predominantly Symmetric Abnormalities
- Section 2 Sellar, Perisellar and Midline Lesions
- Section 3 Parenchymal Defects or Abnormal Volume
- Section 4 Abnormalities Without Significant Mass Effect
- 97 Dural Venous Sinus Thrombosis
- 98 Dural Arteriovenous Fistula
- 99 Subarachnoid Hemorrhage
- 100 Laminar Necrosis
- 101 Neurocutaneous Melanosis
- 102 Superficial Siderosis
- 103 Polymicrogyria
- 104 Seizure-Related Changes (Peri-Ictal MRI Abnormalities)
- 105 Embolic Infarcts
- 106 Focal Cortical Dysplasia
- 107 Tuberous Sclerosis Complex
- 108 Dysembroplastic Neuroepithelial Tumor (DNT, DNET)
- 109 Nonketotic Hyperglycemia With Hemichorea–Hemiballismus
- 110 Hyperdensity Following Endovascular Intervention
- 111 Early (Hyperacute) Infarct
- 112 Acute Disseminated Encephalomyelitis (ADEM)
- 113 Susac Syndrome
- 114 Diffuse Axonal Injury
- 115 Multiple Sclerosis
- 116 Progressive Multifocal Leukoencephalopathy (PML)
- 117 Nodular Heterotopia
- 118 Neurosarcoidosis
- 119 Meningeal Carcinomatosis
- 120 Meningitis (Infectious)
- 121 Perineural Tumor Spread
- 122 Moyamoya
- 123 Central Nervous System Vasculitis
- 124 Subacute Infarct
- 125 Active Multiple Sclerosis
- 126 Capillary Telangiectasia
- 127 Developmental Venous Anomaly
- 128 Immune Reconstitution Inflammatory Syndrome (IRIS)
- 129 Ventriculitis
- Section 5 Primarily Extra-Axial Focal Space-Occupying Lesions
- Section 6 Primarily Intra-Axial Masses
- Section 7 Intracranial Calcifications
- Index
- References
Summary
Specific Imaging Findings
The diagnosis of uncomplicated infectious meningitis is a clinical one and imaging is not indicated. If done, the most specific findings are high CSF signal intensity on FLAIR images and leptomeningeal/subarachnoid space contrast enhancement. Contrast enhancement may also be seen on CT, but not to the extent that it is shown by MRI. Patients suspected of having complications need to be imaged with MRI including DWI, post-contrast images, T2*-weighted images (to look for thrombosed cortical veins), MRV and MRA. Diffusion imaging is very helpful in demonstrating reduced diffusion in any local collection of pus (abscess, empyema, ventriculitis) and also in detecting acute infarctions. Ventricular debris with an irregular level is the most frequent sign of ventriculitis, while hydrocephalus and ependymal enhancement are less commonly encountered. Large subdural sterile fluid collections are typical in children with Haemophilus influenza meningitis. Tubercular meningitis has a predilection for involvement of basal cisterns, especially the interpeduncular fossa, typically with thick enhancing exudates, frequently leading to infarcts in the territories of the middle cerebral artery perforating vessels.
Pertinent Clinical Information
Infectious meningitis is more common in children and it can grossly be divided into bacterial (pyogenic), viral (lymphocytic) and tubercular. The last two may occasionally assume a chronic form. The diagnosis of meningitis is a clinical one (not an imaging one) and is based on abnormal CSF that shows: high numbers of white blood cells, high protein, and low glucose. The most important clinical symptoms are: fever, headaches, signs of increased intracranial pressure, nuchal rigidity, irritability, lethargy and altered mental status and seizures. Hyperreflexia may also be present. Complications of meningitis occur in up to 50% of patients, the most common ones being ventriculomegaly, subdural collection, and infarct.
- Type
- Chapter
- Information
- Brain Imaging with MRI and CTAn Image Pattern Approach, pp. 247 - 248Publisher: Cambridge University PressPrint publication year: 2012