In two patients with surgically proved CSF fistula through the facial nerve canal, MR and CT examinations showed smooth enlargement of the geniculate fossa with CSF signal. In the clinical setting of CSF otorrhea or rhinorrhea, the presence of an enlarged labyrinthine facial nerve canal and enlarged geniculate fossa on CT scans and CSF intensity on MR images strongly suggests a CSF fistula through the facial nerve canal. (+info)
(2/406) Evaluation of CSF leaks: high-resolution CT compared with contrast-enhanced CT and radionuclide cisternography.
BACKGROUND AND PURPOSE: Radiologic evaluation of CSF leaks is a diagnostic challenge that often involves multiple imaging studies with the associated expense and patient discomfort. We evaluated the use of screening noncontrast high-resolution CT in identifying the presence and site of CSF rhinorrhea and otorrhea and compared it with contrast-enhanced CT cisternography and radionuclide cisternography. METHODS: We retrospectively reviewed the imaging studies and medical records of all patients who were evaluated for CSF leak during a 7-year period. Forty-two patients with rhinorrhea and/or otorrhea underwent high-resolution CT of the face or temporal bone and then had CT cisternography and radionuclide cisternography via lumbar puncture. The results of the three studies were compared and correlated with the surgical findings in 21 patients. RESULTS: High-resolution CT showed bone defects in 30 of 42 patients (71%) with CSF leak. High-resolution, radionuclide cisternography and CT cisternography did not show bone defects or CSF leak for 12 patients (29%) who had clinical evidence of CSF leak. Among the 30 patients with bone defects, 20 (66%) had positive results of their radionuclide cisternography and/or CT cisternography. For the 21 patients who underwent surgical exploration and repair, intraoperative findings correlated with the defects revealed by high-resolution CT in all cases. High-resolution CT identified significantly more patients with CSF leak than did radionuclide cisternography and CT cisternography, with a moderate degree of agreement. CONCLUSION: Noncontrast high-resolution CT showed a defect in 70% of the patients with CSF leak. No radionuclide cisternography or CT cisternography study produced positive results without previous visualization of a defect on high-resolution CT. CT cisternography and radionuclide cisternography may be reserved for patients in whom initial high-resolution CT does not identify a bone defect or for patients with multiple fractures or postoperative defects. (+info)
(3/406) The functional shift of the mandible in unilateral posterior crossbite and the adaptation of the temporomandibular joints: a pilot study.
Changes in the functional shift of the mandibular midline and the condyles were studied during treatment of unilateral posterior crossbite in six children, aged 7-11 years. An expansion plate with covered occlusal surfaces was used as a reflex-releasing stabilizing splint during an initial diagnostic phase (I) in order to determine the structural (i.e. non-guided) position of the mandible. The same plate was used for expansion and retention (phase II), followed by a post-retention phase (III) without the appliance. Before and after each phase, the functional shift was determined kinesiographically and on transcranial radiographs by concurrent recordings with and without the splint. Transverse mandibular position was also recorded on cephalometric radiographs. Prior to phase I, the mandibular midline deviated more than 2 mm and, in occlusion (ICP), the condyles showed normally centred positions in the sagittal plane. With the splint, the condyle on the crossbite side was displaced 2.4 mm (P < 0.05) forwards compared with the ICP, while the position of the condyle on the non-crossbite side was unaltered. After phase III, the deviation of the midline had been eliminated. Sagittal condylar positions in the ICP still did not deviate from the normal, and the splint position was now obtained by symmetrical forward movement of both condyles (1.3 and 1.4 mm). These findings suggest that the TMJs adapted to displacements of the mandible by condylar growth or surface modelling of the fossa. The rest position remained directly caudal to the ICP during treatment. Thus, the splint position, rather than the rest position should be used to determine the therapeutic position of the mandible. (+info)
(4/406) Supporting cells contribute to control of hearing sensitivity.
The mammalian hearing organ, the organ of Corti, was studied in an in vitro preparation of the guinea pig temporal bone. As in vivo, the hearing organ responded with an electrical potential, the cochlear microphonic potential, when stimulated with a test tone. After exposure to intense sound, the response to the test tone was reduced. The electrical response either recovered within 10-20 min or remained permanently reduced, thus corresponding to a temporary or sustained loss of sensitivity. Using laser scanning confocal microscopy, stimulus-induced changes of the cellular structure of the hearing organ were simultaneously studied. The cells in the organ were labeled with two fluorescent probes, a membrane dye and a cytoplasm dye, showing enzymatic activity in living cells. Confocal microscopy images were collected and compared before and after intense sound exposure. The results were as follows. (1) The organ of Corti could be divided into two different structural entities in terms of their susceptibility to damage: an inner, structurally stable region comprised of the inner hair cell with its supporting cells and the inner and outer pillar cells; and an outer region that exhibited dynamic structural changes and consisted of the outer hair cells and the third Deiters' cell with its attached Hensen's cells. (2) Exposure to intense sound caused the Deiters' cells and Hensen's cells to move in toward the center of the cochlear turn. (3) This event coincided with a reduced sensitivity to the test tone (i.e., reduced cochlear microphonic potential). (4) The displacement and sensitivity loss could be reversible. It is concluded that these observations have relevance for understanding the mechanisms behind hearing loss after noise exposure and that the supporting cells take an active part in protection against trauma during high-intensity sound exposure. (+info)
(5/406) A gene for fluctuating, progressive autosomal dominant nonsyndromic hearing loss, DFNA16, maps to chromosome 2q23-24.3.
The sixteenth gene to cause autosomal dominant nonsyndromic hearing loss (ADNSHL), DFNA16, maps to chromosome 2q23-24.3 and is tightly linked to markers in the D2S2380-D2S335 interval. DFNA16 is unique in that it results in the only form of ADNSHL in which the phenotype includes rapidly progressing and fluctuating hearing loss that appears to respond to steroid therapy. This observation suggests that it may be possible to stabilize hearing through medical intervention, once the biophysiology of deafness due to DFNA16 is clarified. Especially intriguing is the localization of several voltage-gated sodium-channel genes to the DFNA16 interval. These cationic channels are excellent positional and functional DFNA16 candidate genes. (+info)
(6/406) MRI examination of the masticatory muscles in the gray wolf (Canis lupus), with special reference to the M. temporalis.
We examined the head of the gray wolf (Canis lupus) using MRI methods. Although the arising surface of the M. temporalis was not so enlarged in the frontal bone, the small frontal bone did not disturb the M. temporalis from occupying the lateral space of the frontal area in the gray wolf as in the domesticated dog. In the gray wolf, it is suggested that the M. temporalis may not be well-developed in terms of size of arising area, but in the thickness of running bundles. We suggest that the dog has changed the three-dimensional plan of the M. temporalis during the domestication and that the M. temporalis has developed a large arising surface in the frontal bone and lost the thickness of belly in the frontal area in accordance with the enlargement of the frontal bone and the increase in brain size. (+info)
(7/406) Chondroblastoma of the temporal bone: a clinicopathologic study of five cases.
Chondroblastoma is a rare benign bone tumor. It commonly affects the epiphysis of long bones during the second and third decades of life. Chondroblastoma of the temporal bone is extremely rare. We reviewed five cases of chondroblastoma arising in the temporal bone. Four cases were female and one was male. The ages ranged from 41 to 60 years (mean, 53.6 years). All cases involved the temporal bone. Three involved the left side and two the right. Chief complaints were long-standing localized pain and hearing difficulty. A sharply demarcated lobulated mass was the main radiological finding. Microscopic findings were those of chondroblastoma of usual locations. Two cases showed aneurysmal bone cyst-like areas. Immunohistochemical studies for CD34, CD99, S-100 protein and cytokeratin were performed. Tumor cells were diffusely positive for S-100 protein in three cases and weakly positive for cytokeratin in one case. CD34 and CD99 were negative in all cases. In summary, chondroblastoma of the temporal bone is rare and occurs in older age group than reported cases of chondroblastoma of the usual location in the literature. (+info)
(8/406) Sound- and pressure-induced vertigo associated with dehiscence of the roof of the superior semicircular canal.
In many types of peripheral vertigo, imaging is not part of the initial evaluation. We present a patient with sound- and pressure-induced vertigo associated with bony dehiscence of the roof of the superior semicircular canal. The diagnosis of this new entity can only be made by high-resolution coronal CT imaging of the temporal bones. In patients with this symptom complex, CT should be performed early in the diagnostic workup. (+info)