E-Book, Englisch, 448 Seiten, ePub
ISBN: 978-3-13-257805-0
Verlag: Thieme
Format: EPUB
Kopierschutz: 6 - ePub Watermark
The features:
Condenses information to the core questions of the diagnostic problem at hand without oversimplifying: What does the clinician want to know? What must be included in the findings, and what differential diagnosis must be excluded?
Clear and didactic organization of information in pathogenesis, clinical findings, and CT morphology
Convenient summaries, offset by a second color, provide information to be used during the CT examination that assure that nothing will be overlooked
Detailed descriptions of normal anatomy with normal values help to differentiate pathologic from normal findings.
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Autoren/Hrsg.
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Weitere Infos & Material
Computed Tomography of the Head
Anatomy of the Head
1 Fundamentals
Clinical Aspects
Technical Aspects
2 Craniocerebral Trauma
Closed and Open Head Injuries
Skull Fractures
Cerebral Contusion
Epidural Hematoma
Traumatic Subarachnoid Hemorrhage
Subdural Hematoma, Acute and Chronic
Subdural Hygroma
Gunshot Injuries
Other Open Brain Injuries
Traumatic Vascular Injuries
Late Sequelae of Head Trauma
3 Cerebrovascular Diseases
Brain Infarction
Hypertensive Intracerebral Hemorrhage
Arteriovenous Malformations
Aneurysmal Subarachnoid Hemorrhage
Thromboses
4 Inflammatory Diseases
Brain Abscess, Bacterial
Tuberculosis
Sarcoidosis
Herpes Simplex Encephalitis
Toxoplasmosis
Cryptococcosis
Neurocysticercosis
Nocardiosis
Listeriosis
Lyme Disease
Progressive Multifocal Leukoencephalopathy
Progressive Diffuse Leukoencephalopathy
5 Intracranial Tumors
Neuroepithelial Tumors
Ependymal Tumors
Choroid Plexus Tumors
Neuroepithelial Tumors of Unknown Origin
Neuronal and Mixed Neuronal/Glial Tumors
Pineal Parenchymal Tumors
Embryonal Tumors
Cranial Nerve Tumors
Meningeal Tumors
Lymphomas
Germ-Cell Tumors
Cysts and Tumorlike Lesions
Tumors of the Sellar Region
Local Extension of Regional Tumors
Metastases
6 Degenerative and Demyelinating Diseases
Degenerative Diseases
Other Radiologic Findings in Dementia
Diseases of the White Matter
7 Congenital Brain Diseases
Phacomatoses
Dandy-Walker Malformation
Arachnoid Cysts
Corpus Callosum Dysplasia
Chiari Malformation
8 Postoperative Findings and Follow-Up
Ventriculoperitoneal and Ventriculoatrial Shunt
Follow-Up after Tumor Resection
9 Facial Skeleton and Skull Base
Fundamentals
Inflammatory Sinus Disease
Tumors and Mass Lesions
Traumatic Lesions
Midfacial and Skull Base Fractures
Computed Tomography of the Spine
Anatomy of the Spine
10 Fundamentals
Clinical Aspects
Evaluation and Interpretation of Findings
Technical Aspects
11 Anatomy
Bone
Intervertebral Disks
Blood Vessels
Ligaments
Spinal Cord and Spinal Nerve Roots
Spinal Meninges
Epidural Space
12 Functional and Structural Abnormalities
Congenital Functional and Structural Abnormalities of the Spine
Acquired Functional and Structural Abnormalities of the Spine
13 Intraspinal Lesions
Extradural Masses
Intradural Extramedullary Masses
Intramedullary Masses
14 Inflammatory Diseases
Infections
Rheumatoid Arthritis
Paget Disease (Osteitis Deformans)
Multiple Sclerosis
2 Craniocerebral Trauma Closed and Open Head Injuries Closed Head Injuries A head injury is classified as “closed” if it leaves the dura intact. Unlike gunshot injuries, for example, traumatic head injuries caused by a force acting over a large area (motor vehicle accidents, falls) do not penetrate the dura. Because the dura is firmly adherent to the inner table of the skull, however, it may be lacerated by a skull fracture (Fig. 1.9 b). Open Head Injuries An open head injury is one in which the dura has been breached (Fig. 1.13 b). These injuries are generally caused by a violent force acting on a small area, as in a gunshot injury or an impact from a sharp-pointed object. Open head injuries include frontobasal fractures and temporal bone fractures with cerebrospinal fluid (CSF) leakage. Immediate surgical treatment is a priority in open head injuries, to reduce the ever-present risk of infection. Skull Fractures Frequency: a common computed tomography (CT) finding in patients with head injury. Suggestive morphologic findings: discontinuity in the bone; diploë not separated from the fracture line by cortical bone; other linear discontinuities. Procedure: if plain skull films demonstrate a fracture, obtain thin-slice cranial CT scans to exclude intracranial hemorrhage. Other studies: plain skull films are good for demonstrating calvarial fractures, but it is essential to detect or exclude an intracranial mass lesion. Checklist for scan interpretation: Fracture depressed (by more than the width of the calvarium)? Burst fracture (vertex) or bending fracture? Intracranial displacement of fragments? Intracranial air signifying dural injury? Accompanying hemorrhage or contusion? Pathogenesis Skull fractures should not be considered in isolation, but must be viewed in connection with lesions of the brain parenchyma and other intracranial structures (blood vessels, cranial nerves). A skull fracture is commonly associated with cranial nerve lesions, vascular injuries, and dural injuries that create portals for the entry of air and microorganisms and for CSF leakage. At the same time, the inability to visualize a fracture does not exclude extensive cerebral contusions or intracranial hematomas. Generally, it is not the fracture itself that is of primary interest in head injuries (at least not a calvarial fracture) but the space-occupying or disruptive intracranial lesions that may accompany the fracture. Frequency Frequency data will vary depending on the make-up of the clinical population, but the following general guidelines may be helpful: • Nearly one-third of head-injured patients do not have a skull fracture, including cases with a fatal outcome. • When a skull fracture is detected, the likelihood of brain injury is increased 30-fold. Clinical Manifestations The clinical manifestations of skull fractures are as varied and diverse as the potential sites of occurrence. • A petrous bone fracture may be manifested by bleeding from the ear or a collection of blood behind the tympanic membrane. • Frontobasal fractures are often associated with unilateral or bilateral periocular hematomas (“monocle” or “eyeglass” hematomas). • Fractures of the sphenoid wing may cause blindness due to rupture or infarction of the optic nerve. • If the fracture involves the sella, avulsion of the pituitary stalk can lead to hormonal deficits. • Fractures of the cribriform plate often result in anosmia. • The cranial nerves most commonly involved by basal skull fractures are the trochlear nerve, trigeminal nerve (first and second divisions), facial nerve, and vestibulocochlear nerve. CT Morphology Fractures are clearly demonstrated by CT when the fracture line is perpendicular to the scanning plane (Fig. 2.1). Fractures that run along the plane of the scan may be missed. Differential Diagnosis Cranial sutures should not be mistaken for fracture lines. Differentiation is aided by noting that with a suture, the diploë is separated from the gap by cortical bone. In a fracture, however, the diploë borders directly on the fracture gap. Comparison with the opposite side also helps to identify sutures. Vascular channels generally have a visible sclerotic margin. Fig. 2.1 Spectrum of CT findings in open head injury. Many such injuries result from a blow to the face or forehead, creating a coup-contrecoup mechanism with marked occipital lesions and less severe frontal lesions. The scans above show a discontinuity in the right anterior calvarium, consistent with a frontal skull fracture (a, bone window). Scanning with a soft-tissue window, just below the scan level in a, shows blood in the frontal interhemispheric fissure (b), with no other significant signs of injury. Intracranial air bordering the fracture line in panel a signifies an open skull fracture. Follow-Up The main role of CT in follow-up is to check for CSF leakage in patients who have sustained an open head injury. Moreover, follow-up is generally advised in patients with initially mild-appearing parenchymal injuries such as contusions and in patients with small intracranial hemorrhages, particularly if clinical deterioration cannot be inferred from the patient’s neurologic status because of intoxication or other causes. Cerebral Contusion Frequency: a common CT finding in head-injured patients. Suggestive morphologic findings: acute hypodense lesions, usually located in the frontal or temporal region. Hyperdense hemorrhage appears after a variable delay. Procedure: schedule CT follow-ups postoperatively and as dictated by intracranial pressure (herniation, hemorrhage after decompression). Other studies: magnetic resonance imaging (MRI) is more sensitive than CT in the subacute stage (especially with diffuse axonal injury and other shearing injuries; see below). Checklist for scan interpretation: Location and extent of contusions? Hemorrhagic contusions? Associated injuries (calvarial fracture, basal skull fracture, petrous bone fracture, subdural or epidural hematoma, traumatic subarachnoid hemorrhage)? Pathogenesis Contusions are caused by acceleration or deceleration trauma to the head (Fig. 2.2). The lesions are characterized morphologically by edema of the brain tissue, with a variable hemorrhagic component. Fig. 2.2a, b Cerebral contusion. Contusions appear on CT as patchy hypodensities. A hemorrhagic component may be absent, as in the bifrontal contusions shown here. The location of cerebral contusions is governed by the following principles: • Relative differences in the acceleration and deceleration of the calvarium and brain cause forces to act over a broad area of brain tissue according to the coup-contrecoup principle: the brain tissue is first injured at the site of impact (the calvarium is accelerated toward the underlying brain) and then on the opposite side of the skull (the moving brain strikes the inner surface of the decelerating calvarium). The contrecoup lesions may be more severe than the coup lesions at the site of impact. • Most contusions occur in the frontal or temporal brain (Fig. 2.3), presumably partially due to the rough-edged bony structures that occur in those areas. Occipital contusions are less common owing to the smooth inner surface of the occipital calvarium. • Shearing injuries are also common in head-injured patients. They are caused by the shear strain that develops at the gray-white junction due to the different acceleration properties of the gray and white matter. The lesions consist of axonal injuries and the rupture of very small vessels. The corpus callosum and subcortical white matter are most commonly affected. Hemorrhage within contusions can be identified on CT scans. Although MRI can demonstrate increased T2-weighted signal intensity with much greater sensitivity, practical problems have prevented the use of this modality, at least in the early stages. Frequency Examination of trauma patients is a field for CT, and cerebral contusions are consistently detected in patients with relatively severe head trauma. Fig. 2.3 Spectrum of CT findings in contusion. These scans illustrate the typical features of hemorrhagic contusions in different patients. a A small hemorrhage rimmed by hypodense edema is visible in the right frontal lobe. There is associated traumatic subarachnoid bleeding in the right basal cisterns. b A large hemorrhagic contusion with prominent perifocal edema. c Coup and contrecoup lesions. A fracture is evident in the left frontoparietal calvarium, and a hemorrhagic contusion is visible on the opposite side in the area of the right parieto-occipital junction. Intraventricular blood is also present on the right side. d The extensive hypodensity almost filling the entire right frontal lobe is a hemorrhagic area at the center of a contusion. A small ring artifact is visible in front of the internal occipital protuberance. Clinical Manifestations Patients often show decreased vigilance...
