Otogenic intracranial inflammations: role of magnetic resonance imaging.

The clinical course of acute otitis media is usually short, and the process terminates because of the host's immune system, the infection-resistant properties of the mucosal linings, and the susceptibility of the major organisms (beta-hemolytic streptococcus or pneumococcus) to penicillin. However, a small proportion (1% to 5%) of untreated or inadequately treated patients may experience complications. Prior to the development of an intracranial complication of otomastoiditis, warning symptoms or signs may be evident; these include severe earache, severe headache, vertigo, chills and fever, and meningeal symptoms and signs. Increasing headache, particularly temporoparietal headache near the affected ear, often indicates an impending intracranial complication. This symptom, often the only indication of an epidural abscess, demands prompt investigation and medical and surgical intervention. In our experience, computed tomography (CT) permits accurate diagnosis of acute coalescent or latent (masked) mastoiditis and its associated complications. However, magnetic resonance imaging (MRI) remains the study of choice to evaluate otogenic intracranial complications. This article demonstrates the important role of MRI in diagnosing various stages of acute otomastoiditis and its associated complications.

Orbital subperiosteal hematoma, cholesterol granuloma, and infection. Evaluation with MR imaging and CT.

Orbital subperiosteal space, a potential space, is an important entity due to its unique anatomy and susceptibility to various pathologic processes. CT scan and MR imaging are important tools in the diagnosis of orbital subperiosteal hematomas, cholesterol granulomas, and infections. MR imaging has emerged as the modality of choice in the evaluation of hematomas and infections of this space due to its multiplanar capability and various imaging sequences giving better information. High-resolution CT scan offers good differentiation in most of these cases. Osseous changes in a cholesterol granuloma is better seen in CT scan, although MR imaging offers better differentiation from epidermoid or dermoid cysts and other subperiosteal process, as well as lacrimal fossa lesions. Subperiosteal abscesses are best evaluated using MR imaging.

Imaging studies in patients with central vestibular disorders.

MR is the radiologic examination of choice when a patient's symptoms indicate the presence of some retrolabyrinthine pathology. CT dynamic studies now permit both heart and brain assessment for poor blood circulation problems of the hindbrain.

Potential use of in vivo proton spectroscopy for head and neck lesions.

Early experience with in vivo MRS has shown its potential for obtaining biochemical information, thus enhancing the diagnostic sensitivity of MRI studies. Further work on combined MRI and in vivo MRS is needed, with the goal of characterization and abnormal conditions according to their spectral patterns and for identification of tumor markers. We presented in this communication our preliminary results. It seems that the resonance from melanin can be used as a marker for melanotic tumors.

Central auditory and vestibular pathology.

MR is the radiologic examination of choice when a patient's symptoms indicate the presence of some retrolabyrinthine pathology. CT dynamic studies now permit both heart and brain assessment for poor blood circulation problems of the hindbrain.

Dynamic computed tomography and its application to ophthalmology.

In this review of 31 patients, dynamic CT is discussed as a valuable tool in the study of the dynamics of blood flow in patients with unexplained visual problems that may be related to ischemic optic neuropathy. Dynamic CT scans are obtained by rapid-sequence CT imaging during and following a rapid bolus injection of intravenous contrast medium. It demonstrates the initial passage of contrast material through the area of interest, thus giving a true picture of the degree of vascularity and the dynamics of blood flow.

Paraorbital tumors and tumor-like conditions: role of CT and MRI.

Tumors and tumor-like conditions of the paraorbital tissues that affect the eye usually require CT or MR imaging for complete evaluation. This article provides an overview of the wide variety of pathologic conditions to be considered when a paraorbital tumor is discovered or suspected. Some of the CT and MR imaging features of these disorders that aid in the differential diagnosis are reviewed.

Rapid dynamic CT scanning to distinguish schizophrenic from normal subjects.

Rapid dynamic computerized axial tomography (CT) density-time curves were used to detect abnormal brain regions in groups of controls and DSM-III diagnosed schizophrenics. Density-time curves were designated as plateau curves if, following a bolus injection of contrast material, they exhibited a plateau from the peak value rather than a decrease. Five of the 10 schizophrenics versus none of the 11 controls were found to possess two or more plateau curves. The physiological basis for the plateau curves is not known, but an increase in blood-brain-barrier permeability could be involved.

CT in the evaluation of the orbit and the bony interorbital distance.

The distance between the orbits and their individual dimensions are important in the diagnosis of craniofacial anomalies. Most observers rely on standard radiographs for measuring the bony interorbital distance. Tomography of the skull base and orbital computed tomography (CT) can also be used. This article describes the normal range of the bony interorbital distance and other useful orbital linear and angular measurements as determined from a series of CT scans of the orbits in 400 adults who had CT for other purposes. The normal interorbital distance measured at the posterior border of the frontal processes of the maxilla on nonrotated scans, in the plane of the optic nerve, ranges from 2.29 to 3.21 cm (average, 2.67 cm) in men and 2.29 to 3.20 cm (average, 2.56 cm) in women. The widest interorbital distance lies behind the posterior poles of the globes. This ranges from 3.16 to 4.10 cm (average, 3.37 cm) in men and 2.93 to 3.67 cm (average, 3.20 cm) in women.

CT densitometry of the cochlear capsule in otosclerosis.

Cochlear otosclerosis can be recognized in most cases by high-definition axial and coronal CT images. However, routine technique does not allow a quantitative measurement of the changes. Reported here is a study of cochlear CT densitometry. The densitometric profile of the cochlear capsule was obtained in 10 ears with normal hearing and 50 ears in 27 patients with known clinical otosclerosis and progressive mixed-type hearing loss. Patients with hearing loss had decreased absorption of as much as 60% in comparison to the normal range. In 42 ears with abnormal densitometric profiles, the changes were visibly apparent on the CT images, whereas in eight others, the densitometric profile alone demonstrated decreased absorption.

Diagnostic potential of CT in neurotological disorders.

The reliability of a neurotological evaluation in differentiating labyrinthine (end organ) lesions from retrolabyrinthine lesions has been well established. The purpose of this communication is to determine the diagnostic potential of computed tomography (CT) in patients suspected of having retrolabyrinthine lesions on the basis of their neurotological evaluations. Our study indicates that the validity of central vestibular and audiometric signs can be best substantiated with CT. The anatomy of neurovascular bundles within the internal auditory canal and cerebellopontine cistern can be readily visualized and identified by CT pneumocisternomeatography. By obtaining appropriate thin CT sections not only can very small lesions be identified but their anatomic locations can also be accurately established. CT pneumocisternomeatography is the method of choice to diagnose an intracanalicular acoustic neuroma. An unusually large vascular loop of the internal auditory canal may be responsible for sensorineural hearing loss and tinnitus in some patients.

Multidirectional and computerized tomography of the vestibular aqueduct in Meniere's disease.

Multidirectional and computerized tomography have been used for the radiographic assessment of the vestibular aqueduct in Meniere's disease. The results of studies performed by us and/or other authors indicate that there is a statistically significant difference in the size of the vestibular aqueduct between the Meniere's and control groups (in Meniere's disease the vestibular aqueduct is often narrowed or obliterated); and that periaqueductal pneumatization is often decreased or absent in ears affected by Meniere's disease. Recent histological studies performed on temporal bones of patients with Meniere's disease have confirmed these radiographic observations.

CT in the evaluation of the vestibulocochlear nerves and their central pathways. Evaluation of neurotologic disorders.

CT has evolved to become an important technique for the diagnosis of neurotologic disorders. By obtaining thin sections, the central pathway of the vestibulocochlear nerve can be rather properly evaluated with satisfactory clinical correlation when pathology exists. The validity of central vestibular and audiometric signs can be best substantiated with CT. The functional neuroanatomy of the vestibulocochlear and vestibulo-oculomotor systems is discussed. Results of the assessment of endocranial lesions involving the vestibulocochlear system are presented.

Computed tomography of the spine: curved coronal reformations from serial images.

A new imaging format described here uses nonplanar reformations that follow the contour of curved structures intersected by a series of regularly spaced CT scans. The CT scanning procedure is described, and algorithmic details of this new format are presented. A standard set of reformatted images is suggested, and clinical examples are given to illustrate the diagnostic value of this new format.

High resolution and dynamic sequential computed tomography. Use in the evaluation of glomus complex tumors.

Computed tomography (CT) has been used to investigate the presence, site, and extent of glomus complex tumors. High resolution CT scanning can accurately evaluate invasion of cervical soft tissues, intratympanic or intracranial extension, and bony involvement of the skull base. Glomus tumors can be differentiated by CT angiographic dynamic study from most other tumors in the head and neck because of their profuse vascularity and their intense enhancement seen on dynamic CT during arterial phase. A glomus tympanicum or extension of a glomus jugulare into the hypotypanum can be best demonstrated by high resolution CT using target review image reconstruction. Glomus tumor in the middle ear can be differentiated from other masses by CT dynamic study and the computer-generated density time curves.

Dandy-Walker syndrome studied by computed tomography and pneumoencephalography.

Based on air studies, some authors have disputed the ability of computed tomography (CT) to diagnose posterior fossa cysts. The authors correlated the pneumoencephalographic, CT, and pathological findings in 4 patients with classic Dandy-Walker syndrome. Three cases had been misdiagnosed as retrocerebellar arachnoid cysts because the fourth ventricle was incorrectly considered normal on brow-up or erect air studies, reflecting the inability of such studies to evaluate an agenetic vermis and deficient posterior medullary velum which are characteristic of Dandy-Walker malformation. Careful correlation with autopsy findings showed that even with complete agenesis of the inferior vermis, if the slit between the cerebellar hemispheres is narrow, the fourth ventricle could be misinterpreted as normal on pneumoencephalography and sagittal CT. Radionuclide studies, a small amount of air, or metrizamide may be needed to determine whether the cyst communicates with the subarachnoid space.

Hindbrain circulation and its evaluation by dynamic computed tomography.

Permanent or transient reduction of blood flow to the end-organs and to the hindbrain is the single major cause of vestibular disorders and a common cause of sensorineural hearing loss. New imaging modalities have become available which allow the recognition of focal areas of hindbrain ischemia in the prestroke stage. The correlation between focal ischemic pathology and clinical findings opens a new approach to the mapping of central pathology. In addition a detailed knowledge of the vascular anatomy of the hindbrain is indispensable for the development of new microvascular surgical techniques aimed at the restoration of sufficient blood supply.