Biomedical subjects
Publications and source records attributed to U Fisch.
The footplate only situation remains the greatest challenge of ossicular reconstruction. This article discusses the long term results obtained with a new type of columella, the Spandrel, which combines the rigidity necessary for sound transmission with the flexibility required to comply with the dynamic movements of the neotympanum.
Twenty years experience of lateral parotidectomy as suspical treatment for pleomorphic adenoma are reviewed. All cases were managed at the ORL Clinic of the University of Zürich. 167 patients were followed for the frequency of possible recurrent tumors. Three patients (3/123) operated primarily developed a recurrences. Recurrences appeared after an average of 10 years, ranging from 1-30 years. The follow-up time varied from 1 to 21 years (average, 8 years). 39% (13 of 33) of the patients, who were re-operated for a recurrent tumor, developed another recurrence. The second recurrence appeared after an average of 10 years, ranging from 1-22 years. A persistent partial paresis of the facial nerve was found in 1% of the patients operated primarily and in 9% of the patients operated more than once. No paralysis was seen. We now choose "en-bloc" resections of pleomorphic adenomas without intra-operative opening of the tumor capsule as the treatment of choice. This treatment was possible in 83% of all cases, using a lateral parotidectomy. If tumor extends into the medial parotid lobe, total parotidectomy is required.
Precise angiographic evaluation of the cerebrovascular system and radiographically controlled balloon occlusion of the internal carotid artery have considerably changed the risk involved with carotid surgery at the skull base. Preoperative permanent balloon occlusion of the internal carotid artery was used in three patients with infiltrative carotid body tumors. Embolization and definitive preoperative control of the carotid artery provided ideal conditions for focusing the surgeon's attention on radical removal of tumor with maximal functional preservation of the adjacent cranial nerves.
Forty-eight surgical specimens were examined histologically and the case histories reviewed to determine the histopathologic features of embolized paragangliomas (glomus tumors) in relation to the time interval between embolization and surgery. Different degrees of thrombus formation and of multinucleated foreign body giant cells occurred during the first 7 days after embolization; thereafter, glant cells with active phagocytosis, fragmentation of embolic material, and partial revascularization were observed. Only one third of the tumor vessels were embolized. Complete obliteration of 40% of embolized vessels occurred more than 2 months postembolization. The histologic changes induced by embolization in paragangliomas of the head and neck may be classified in four stages. Histologically, the best time for surgery is within 8 days from embolization; surgery performed more than 8 days following embolization, however, is not compromised by revascularization.
A case of aneurysm of the horizontal intratemporal carotid artery with compression of the facial nerve is presented. Exclusion of the aneurysm with an intraluminal balloon did not relieve the facial nerve compression. Surgical resection of the aneurysm and repair of the facial nerve continuity was successfully performed through a combined transmastoid supralabyrinthine approach, after permanent balloon occlusion of the internal carotid artery.
Lying between the carotid bifurcation and the jugular foramen, glomus vagale tumors share characteristics with paragangliomas of those two structures, such as invasion of the carotid artery, destruction of the skull base, and cranial neuropathies. This capability for local invasion provides a therapeutic challenge with regard to the proper assessment of tumor extent and the selection of appropriate treatment. In order to clarify an approach to the management of glomus vagale tumors, we reviewed a 10-year experience with 15 patients treated for this tumor at the University of Zürich Department of Otolaryngology, using a new system of classification. This system highlights the relative position of a vagal paraganglioma to the jugular foramen and is helpful in designing the proper therapy. Pitfalis in surgical technique, recommended preoperative evaluation, and the roles of balloon occlusion and irradiation in the treatment of these tumors, are discussed.
The effects of bilateral vestibular neurectomy on equilibrium and vestibular function were clinically evaluated in two patients more than 15 years after surgery. Both patients had bilateral Menière's disease and their vertiginous spells were permanently resolved after the second vestibular neurectomy. Symptoms of disequilibrium were absent in one patient and mild in the other. Reflexive horizontal eye movements on whole body rotation in darkness were absent on low angular accelerations (2 degrees/s2), but could be elicited with angular accelerations of 20 degrees/s2 or higher. Extravestibular cues generating these eye movements seemed to be unlikely because a "control" patient with complete peripheral vestibular ablation after bilateral subtotal petrosectomy did not present reflexive eye movements under the same stimulus paradigms. An incomplete deafferentiation of the vestibular end organ (rather than regeneration of vestibular nerve fibers) and a consecutive impairment of the central velocity storage mechanism may explain the good functional outcome in our bilateral neurectomized patients.
A consecutive series of 147 transotic operations for the removal of acoustic neuroma is presented. The advantages of this approach over the conventional translabyrinthine technique are several, including 1) a wider surgical access with a circumferential exposure of the internal acoustic meatus and the porus acousticus; 2) the direct visualization and access to the anterior cerebellopontine angle where the facial nerve is usually tenuous and most vulnerable; and 3) the permanent closure of the ear canal and eustachian tube with complete obliteration of the surgical cavity, minimizing cerebrospinal fluid leaks. These advantages have translated into improved surgical outcomes. In our series of 147 patients spanning 11 years, total tumor extirpation was achieved in all patients, with one mortality, three CSF leaks, and one meningitis. The facial nerve was anatomically preserved in 95% of the cases. This approach is capable of attaining the widest, and the most direct access to the cerebellopontine angle without cerebellar retraction.
Soft tissue sarcomas often present a frustrating diagnostic challenge for the pathologist as well as the surgeon. Despite the development of better defined criteria for histopathologic and immunohistochemical evaluation, definitive diagnosis may not be immediately apparent. We report two cases of leiomyosarcoma of the skull base that presented with the clinical diagnosis of schwannoma, a diagnosis confirmed on initial histopathologic examination. It was only after closer review and special immunohistochemical studies that the diagnosis of leiomyosarcoma was made. The methods for diagnosing such tumors using both standard histopathologic criteria and immunohistochemical methods are reviewed. We suggest that all extracranial soft tissue tumors of the skull base be examined by both techniques to avoid delayed or missed diagnosis.
Nine patients with mesenchymal tumors of the skull base have undergone radical tumor excision by the use of the Infratemporal fossa approach. Three cases of chondrosarcoma, two of leiomyosarcoma, and one case each of synovial sarcoma, chondroid chordoma, myxoma, and fibromatosis were managed. In the mean postoperative review time of 6.6 years (range 1.7 to 13) there are no clinical or radiologic signs of recurrence at the primary site in any patient, although two have developed distant metastases. The purpose of this article is to demonstrate that, with aggressive and preferably early surgical management using this type of access to the skull base, complete removal of these tumors can be undertaken, and it is now possible to achieve permanent ablation of this type of pathologic condition at the skull base.
Eight patients with intratemporal hemangiomas involving the facial nerve are reported to present their symptoms, pathology, surgical management, and results. These unusual tumors have a predilection to involve the facial nerve, usually at the geniculate ganglion, internal auditory canal, or middle ear. Patients presented with facial palsy that was sudden, gradual in onset, recurrent, or associated with hemifacial spasm. Symptoms often progressed for years before the diagnosis was made. In two cases the tumor caused bony remodeling with an expansile honeycombed appearance, but no neoplastic production of bone. The facial nerve was comprised either by tumor compression or nerve invasion, as seen in two of our patients. Complete removal of the tumor and rehabilitation of the facial nerve function was attained in each case. Because of the destructive nature of these benign tumors, intratemporal facial nerve grafting was required in five of the eight cases. Results of facial nerve repair were good except in cases of long-standing facial dysfunction.
The transotic approach to the cerebellopontine angle for resection of tumors invading the internal auditory canal provides superior illumination and exposure for optimal preservation of facial nerve function. Separation of facial nerve from tumor is enhanced with an anterior exposure that allows visualization of the intracranial segment of the nerve before tumor removal without significantly increasing total operative time. Facial nerve grafting or hypoglossal-facial anastomosis may be incorporated into the procedure at the time of tumor resection using the transotic approach. When combined with a musculofascial patch secured to the dural defect, the initial subtotal petrosectomy with eustachian tube and middle ear cleft obliteration generally avoids the complication of an immediate or delayed postoperative cerebrospinal fluid leak. The transotic approach is indicated for tumors up to 2.5 cm in size that are not adherent to the brain stem.
The growth rate of acoustic tumors, although slow, varies widely. There may be a continuous spectrum or distinct groups of tumor growth rates. Clinical, audiologic, and conventional histologic tests have failed to shed any light on this problem. Modern immunohistochemical methods may stand a better chance. The Ki-67 monoclonal antibody stains proliferating cells and is used in this study to investigate the growth fraction of 13 skull base schwannomas. The acoustic tumors can be divided into two different growth groups, one with a rate five times the other. The literature is reviewed to see if this differentiation is borne out by the radiologic studies. Distinct growth rates have been reported: one very slow, taking 50 years to reach 1 cm in diameter, a second rate with a diameter increase of 0.2 cm/year, and a third rate five times the second, with a 1.0 cm increase in diameter per year. A fourth group growing at 2.5 cm/year is postulated, but these tumors cannot be followed for long radiologically, since symptoms demand surgical intervention. The clinical implications of these separate growth rates are discussed.
A study of 26 patients with facial nerve schwannomas treated at the University Hospital of Zurich was done. The general clinical features are described, but particular emphasis is placed on tumor histologic findings, recovery of facial function after grafting, and the nature of intracranial facial nerve schwannomas Presenting symptoms are stratified by tumor location, with facial dysfunction being commonest with intracranial tumors, neurotologic symptoms being associated with intracranial tumors, and parotid masses being a feature of extratemporal tumors. We found no differences in tumor histology regardless of site of origin. Clinical, histologic, and radiologic evidence is reviewed, and from this evidence we conclude that intracranial facial nerve schwannomas may be particularly invasive acoustic schwannomas. Recovery of facial movement after grafting the facial nerve is not influenced by graft length or graft type. Prolonged preoperative facial dysfunction has a negative influence on recovery after grafting.
An unusual case of intraorbital teratoma is presented. It was observed for the first time after 4 months when it caused increasing swelling of the maxillary region and proptosis of the eye. The diagnosis was difficult to establish. Repeated computed tomography scans were very helpful in evaluating the progress of the tumor. Surgical intervention with an infratemporal approach was undertaken and proved to be very successful.
This study was performed to determine the area in which and the circumstances under which stapedotomy can be relatively safely performed. Measurements were made from central areas of the medial surface of the stapedial footplate to the utricle, the saccule, and the cochlear duct in 10 normal and 11 otosclerotic temporal bones. The mean distances to the utricle ranged from 1.9 to 2.4 mm, and those to the saccule from 1.7 to 2.1 mm. The minimal distance to the utricle was measured from the posterior (0.58 mm) and superior (0.62 mm) borders of the stapedial footplate. The minimal distances to the saccule were from the anterior (0.76, 0.86, and 1.00 mm) border of the stapedial footplate. All other measurements were of more than 1 mm. The shortest distance between the cochlear duct and the inferior border of the footplate was 0.2 mm. Statistical analysis has shown no significant differences for the mean values obtained in normal and otosclerotic temporal bones. Fathoming of the vestibule below the central and inferior thirds of the footplate surface has shown that there is no likely danger to the vestibular end organs or cochlear duct if manipulations are carried out no deeper than 1 mm below the surface. The safest place for a stapedotomy opening is in the central and inferior-central thirds of the footplate. A stapedotomy piston of 0.4 mm in diameter can be introduced relatively safely to a depth of 0.5 mm in the vestibule over the entire surface of the stapedial footplate.
Electron microscopic examination of intratemporal facial nerve segments removed from 12 patients with persisting facial paralysis following temporal bone fractures revealed that traumatic injury at the geniculum induces retrograde degeneration through the labyrinthine and distal meatal segments of the facial nerve. Fibrosis may occur in the traumatized labyrinthine segment and block regenerating motor fibers. The surgical treatment of traumatic facial nerve injuries should be aimed to avoid or eliminate fibrosis within the labyrinthine segment of the Fallopian canal.