Vertebral artery hypoplasia and hemodynamic impairment in transient global amnesia: a case control study.

Introduction: The aetiology of transient global amnesia (TGA) is still a matter of debate. Besides ischemia of the mesial temporal lobe including the hippocampus, migraine-like mechanisms, epileptic seizures affecting mnestic structures, or venous congestion in the (para) hippocampal area due to jugular vein insufficiency have been discussed. We assessed the diameters of the intracranial arteries of TGA patients compared to controls to identify differences that support the hypothesis of reduced hippocampal perfusion as a pivotal factor in the pathophysiology of TGA. Methods: We reviewed magnetic resonance imaging time of flight angiographies (TOF-MRA) that were acquired during in-patient treatment of 206 patients with acute TGA. Results: The diameters of the vertebral artery (VA) in the V4 segment, the proximal basilar artery, and the internal carotid arteries were measured manually. We compared the findings with TOF-MRA images of an age and sex matched control group of neurological patients without known cerebrovascular pathology. In TGA patients the diameter of the right VA was significantly (p < 0.01) smaller compared to controls (2.09 mm vs. 2.35 mm). There were no significant differences in the diameters of the other vessels. Only the fetal variant of the posterior cerebral artery was slightly more common in TGA. Discussion: The smaller diameter (hypoplasia) of the right VA supports the hypothesis of a contribution of hemodynamic factors to the pathophysiology of TGA. The fact that hypoplasia represents a congenital condition might be the explanation why previous studies failed to find an increased rate of the classical (acquired) vascular risk factors.

Temporal bone imaging using digital volume tomography and computed tomography: a comparative cadaveric radiological study.

PURPOSE: The aim of the present study was to analyze the diagnostic value of some temporal bone structures, e.g., ossicular chain, with digital volume tomography (DVT) compared with computed tomography (CT). METHODS: Radiological imaging for presentation structures of the temporal bone were performed by DVT and CT. Axial and coronal scans in vitro examinations were performed in 38 human temporal bones. 43 structures were defined. The frequency of visualization of these anatomic structures were studied and statistically analyzed. RESULTS: In the present study there was a higher significance of identified structures in DVT. In 15 (34.9%) temporal bone specimens defined structures were found equally in DVT and CT scans of axial images and 12 (27.9%) of coronal images. However, 9 structures (20.1%) of axial scans and 5 structures (11.6%) of coronal scans could be identified statistically significantly (P < 0.05) more often in DVT than in CT. CONCLUSION: Anatomical structures of the temporal bone can be identified in higher significance in DVT than in CT scans.

Early side effects after embolization of a carotid body tumor using Onyx.

The case of a 20-year-old woman with a carotid body tumor of Shamblin class III is reported. Ten hours after preoperative direct intralesional embolization with 20 mL Onyx (ethylene-vinyl alcohol copolymer; Micro Therapeutics, Irvine, Calif), the patient showed symptoms of Horner syndrome and deficits of the hypoglossal and glossopharyngeal nerves. Intraoperative examination 12 hours after Onyx embolization revealed a massive swelling of the hypoglossal and glossopharyngeal nerves. The patient's tongue motility and glossopharyngeal function improved after surgery, but Horner syndrome was still present. Owing to the delayed occurrence of these adverse effects, the optimal time of surgical intervention after Onyx embolization should be discussed and perhaps expedited.

The value of digital volume tomography in assessing the position of cochlear implant arrays in temporal bone specimens.

OBJECTIVES: Radiological evaluation of the position of cochlear implant (CI) devices is an upcoming method for quality control after CI surgery. First, results of imaging of the middle and inner ear with digital volume tomography (DVT) show considerable advantages such as exceptional image quality, thin slice thickness, and low radiation dose. The aim of this study was to evaluate whether DVT is an appropriate method for postoperative imaging of CI patients and to identify the exact position of the implant array within the cochlear by multiple measurements. DESIGN: Thirteen formalin-fixed temporal bone specimens were implanted with a CI array and scanned in DVT. To determine the exact electrode position, these specimens were ground and stained for microscopic measurements. The measurements on grindings acted as a referee and were compared with the measurements in DVT scans. The statistical analysis between the two measurement protocols was performed using the Bland-Altman method. RESULTS: Best achievable agreement between DVT scans and histological reference was shown. Mean differences between DVT and grindings from -1.55 to -65.40 microm were calculated. All means are within the region of accuracy. General positioning of the implant into the cochlea could be verified in all specimens. The exact position of the implanted array within the cochlear scalae could be recognized correctly in 11 of 13 cases in DVT. It was possible to identify shiftings between the tympanic and vestibular scalae in all cases. CONCLUSION: DVT seems to be a convenient technique for postoperative position control after cochlear implantation.