Magnetic resonance imaging following fat obliteration of the frontal sinus.

The paper describes the evaluation of magnetic resonance imaging (MRI) following osteoplastic flap procedure with fat obliteration. MRI scans performed in patients after surgery between 1st January 1986 and 31st December 1997 were evaluated. Outcome parameters were time-dependent changes in the distribution of adipose or connective tissue, development of necroses or oil cysts, recurrences, inflammatory complications, or mucocoeles. Eighty-six postoperative MRI scans from 51 operations were evaluated. In 19 cases between two and five MRI scans were available. Time between surgery and the last MRI scan was 24.1 months on average. We found five mucocoeles. The amount of adipose tissue depictable on the last scan was less than 20% in the majority of cases (53%) and more than 60% in only 18% of cases. Statistical tests and modelling showed a significant decrease of adipose tissue with time, with a median half-life of 15.4 months in a subgroup with at least two MRIs. MRI is at times the most valuable diagnostic tool after frontal sinus obliteration using adipose tissue. The method has some limitations with regard to detection of small (recurrences of) mucocoeles and differentiation between vital adipose tissue and fat necroses in the form of oil cysts. In difficult cases long-term MRI follow-up is necessary for definitive evaluation.

Magnetic resonance imaging in patients with sudden hearing loss, tinnitus and vertigo.

OBJECTIVE: The etiopathogenesis in audiovestibular symptoms can be elusive, despite extensive differential diagnosis. This article addresses the value of magnetic resonance imaging (MRI) in analysis of the complete audiovestibular pathway. STUDY DESIGN: Retrospective evaluation. SETTING: Tertiary referral center. PATIENTS: Consecutive sample of 354 patients (mean age 49 years, range 8 to 86 years) with audiovestibular disorders. INTERVENTION: Contrast-enhanced MRI of the head with thin-slice investigation of the inner ear, internal auditory meatus, and cerebellopontine angle. MAIN OUTCOME MEASURE: All MRIs were evaluated by experienced independent investigators. Statistical analysis was performed using the Statistical Package of Social Sciences data analysis 9.0. RESULTS: MRI abnormalities were seen in 122 of 354 patients (34.5%). The MRIs revealed the following: 4 pathologic conditions (1.1%) of the cochlea/labyrinth, 23 abnormalities (6.5%) at the internal auditory meatus/cerebellopontine angle, 12 pathologic lesions (3.4%) that involved the central audiovestibular tract at the brainstem, 78 microangiopathic changes of the brain (22%), 3 focal hyperintensities of the brain that turned out to be the first evidence of multiple sclerosis in 2 patients and sarcoidosis in 1 patient, and 1 temporal metastasis. Other pathologic conditions, such as parotid gland or petrous bone apex tumors, were unrelated to the audiovestibular symptoms. CONCLUSIONS: This study indicates that contrast-enhanced MRI can be used to assess a significant number of different pathologic conditions in patients with audiovestibular disorders.

Sigmoid and transverse sinus thrombosis after closed head injury presenting with unilateral hearing loss.

Sinus thrombosis has rarely been associated with closed head injury; more often, thrombosis of the sigmoid or transverse sinus is caused by otogenic inflammations or tumours, or occurs during pregnancy. Symptoms are frequently vague, while untreated thrombus progression may be fatal due to venous congestion and infarction. We report a 32-year-old man presenting with right hearing loss, tinnitus and headache 2 days after a closed head injury. Neurological examination showed no additional abnormality. The EEG showed focal bifrontal slowing. CT revealed a fracture of the occipital bone. MRI and MRA demonstrated complete thrombosis of the right sigmoid and transverse sinuses. After 2 weeks of intravenous heparin therapy followed by warfarin, the patient's hearing improved and MRI and MRA showed complete recanalisation of the sigmoid and transverse sinuses. Venous sinus thrombosis can be an undetected sequel to head injury. Appropriate imaging studies should be carried out to enable therapy to be started as soon as possible.

Papillary tumor of the temporal bone.

Papillary tumors of the middle and inner ear have been interpreted histogenetically in many ways. In 1989 Heffner proposed the endolymphatic sac epithelium as a possible origin. These rare tumors are clinically aggressive and can cause extensive temporal bone destruction. Because of this behavior, endolymphatic sac tumors (ELST) were classified as low-grade adenocarcinomas, although metastasis has not yet been documented. Two papillary neoplasms of the temporal bone are presented, which we believe are examples of adenomatous tumors arising from the epithelium of the endolymphatic sac. One was associated with a pituitary adenoma. A third case of a papillary middle ear neoplasm is described that shows histologic features similar to the other two, but it was located in the tympanum and had no connection to the endolymphatic sac. This report focuses on clinical, radiologic, and histologic findings of papillary tumors of the temporal bone with additional emphasis on modern concepts of histogenesis and aspects of differential diagnosis.

Radiological findings in angiofibroma.

Surgery after pre-operative embolization has become the main treatment modality in angiofibroma therapy. As surgical planning is based on precise preoperative tumour evaluation, knowledge of the characteristic growth patterns is of great interest. Analysis of tumour extension and blood supply, as well as methods of controlling intra-operative bleeding, help in determining the appropriate surgical approach. Though benign, angiofibroma demonstrates a locally aggressive nature. This fibrovascular tumour is characterised by typical radiological findings and by predictable growth patterns. The tumour extension and blood supply can be accurately determined by CT, MR imaging and angiography. With classic radiological findings, no pre-operative biopsy is necessary in most angiofibromas. Advances in radiological imaging have contributed to improved surgical planning and tumour resection. The surgeon is able to select the least traumatic approach with secure haemostatic control, which is also critical for avoiding the disturbance of facial skeletal growth in this group of young patients. Embolization, pre-operative autologous donation and the cell saver system for immediate retransfusion of the collected blood after filtration, are important tools for dealing with blood loss in angiofibroma surgery as they minimize homologous blood transfusion.

[Rapid measurement of water vapor partial pressure at the saturation point with a new hybrid humidity sensor]. / Schnelle Messung des Wasserdampfpartialdrucks im Sättigungsbereich mit einem neuartigen Hybrid-Feuchtesensor.

A new hybrid humidity sensor comprising a conventional capacitance humidity sensor and a planar heating element is described. Owing to its short response time of only a few milliseconds, its great measuring accuracy, large measuring range, and simplicity in handling, the sensor is suitable for measuring water vapour partial pressure in gases with rapidly changing flow and direction, e.g. in ventilated patients in the fields of anaesthesia and intensive care medicine. The small dimensions permit measurements at almost any location within the ventilation system.

Osteoplastic frontal sinus surgery with fat obliteration: technique and long-term results using magnetic resonance imaging in 82 operations.

OBJECTIVE: To evaluate the intraoperative and late complications of osteoplastic sinus surgery with fat obliteration with long-term magnetic resonance imaging (MRI) follow-up. METHODS: The operative records of all patients who underwent osteoplastic frontal sinus surgery with fat obliteration between January 1, 1986 and December 31, 1997 were reviewed and the postoperative clinical course and magnetic resonance imaging (MRI) scans were analyzed if available. MRI analyses revealed that changes in the distribution of fatty and fibrous tissue, the development of necrosis or oil cysts, recurrences, inflammatory complications, and mucoceles were time-dependent occurrences. RESULTS: Eighty-two operative records were evaluated and 59 patients were followed 1 to 12 years after surgery. Eighty-six MRI scans in 51 patients were available for analysis. The most frequent intraoperative complications were exposure of orbital fat (19.5%), unintentional fracture of the anterior wall (19.5%), incorrect placement of the anterior wall (17%), and dural injury (9.8%). Persistent changes of the frontal contour (embossment, depression) occurred in 10.2% and the esthetic result was unfavorable in 5.1% of the cases. Mucoceles could be detected in 5 of 51 cases (9.8%). The amount of adipose tissue detectable in the last scan was less than 20% in the majority of cases (53%), and more than 60% in only 18% of the cases. The amount of adipose tissue decreased significantly with time (the median half-life was 15.4 mo). CONCLUSIONS: Osteoplastic frontal sinus surgery with fat obliteration is very useful and successful in patients in whom the frontal sinus is not accessible via an endonasal approach or the natural drainage cannot be reestablished. MRI is currently the most valuable diagnostic tool to evaluate the frontal sinus after obliteration with adipose tissue. The method has some limitations with regard to detection of small recurrent mucoceles and differentiating vital adipose tissue from fat necroses in the form of oil cysts. In these difficult cases, long-term MRI follow-up is necessary.

[Nuclear magnetic resonance tomography after fatty tissue obliteration of the frontal sinus]. / Kernspintomographie nach Fettobliteration der Stirnhöhle.

BACKGROUND: The osteoplastic flap procedure with fat obliteration has been hailed as the gold standard of definitive frontal sinus procedures for chronic inflammatory disease. The value of magnetic resonance imaging (MRI) in postoperative follow-up has not yet been sufficiently examined. METHODS: All postoperative MRI scans performed in patients undergoing surgery between January 1, 1986, and December 31, 1996 were evaluated. The outcome parameters were time-dependent changes in the distribution of fatty or connective tissue and development of necroses or oil cysts, as well as recurrences, inflammatory complications, or mucoceles. RESULTS: Sixty-eight operations were performed in the specified period and a total of 73 postoperative MRI scans from 45 operations were available for evaluation. In 16 cases, between two and five MRI scans were available. The individual time between surgery and the last MRI scan ranged from two weeks to 130 months with an average of 30.1 months. We found four mucoceles 34, 49, 106, and 130 months, respectively. Three of the mucoceles were diagnosed on the first postoperative MRI scan. In the fourth case the mucocele had not been seen on the previous scan. The amount of adipose tissue depictable on the last scan was less than 20% in the majority of cases (58%) and more than 60% in only 18% of cases, although in the latter group the time between surgery and MRI was less than 7 months in half the cases. CONCLUSIONS: MRI is the most valuable diagnostic tool after frontal sinus obliteration using adipose tissue. Despite the good soft tissue differentiation, the method has some limitations with regard to detection of small recurrent mucoceles and differentiation between vital adipose tissue and fat necrosis in the form of oil cysts. In these difficult cases, long-term MRI follow-up is necessary for definitive evaluation. We therefore recommend MRI 1, 2, and 5 years after osteoplastic frontal sinus surgery with obliteration.

Experiences with endonasal surgery in angiofibroma.

Surgery is the most common treatment for angiofibromas, but the approach is still a major point of discussion. Five cases of angiofibroma with typical localisation were treated surgically by an endonasal approach at the Fulda Academic Teaching Hospital from 1994 to 1997. This article presents an analysis of the clinical findings, computer tomography and magnetic resonance imaging, preoperative embolization, operative technique and complications. Endoscopic and radiologic follow-up ranging from 5 to 39 months excluded any residual tumour or recurrence. The endonasal microendoscopic approach with adequate preoperative embolization should be considered as an useful technique for removing tumours with considerable size without using an external incision.

[Bone neogenesis in a rare space-occupying lesion of the inner ear canal]. / Knochenneubildungen in einer seltenen Raumforderung des inneren Gehörgangs.

Hemangiomas of the skull base are rare neoplasms and are easily misdiagnosed as acoustic neuromas when occurring in the internal auditory canal. Among these tumors, ossifying hemangiomas are characterized histologically be newly formed bone tissue within their substance. We describe a 26-year old female patient who presented with left-sided sensorineural hearing loss and tinnitus. T2-weighted magnetic resonance imaging demonstrated a bright space-occupying lesion of the internal auditory canal with extension to the geniculate ganglion. Bony erosions of the internal auditory canal were proved by high-resolution computed tomography. A hemangioma was suspected preoperatively and was resected via a middle cranial fossa approach. Histologically, new bone formations were found in a cavernous hemangioma. In general, radiologic findings can suggest a hemangioma of the internal auditory canal and help to differentiate it from acoustic neuroma. Based on the histological findings of intratumoral bone formation, the hemangioma in our patient was classified as an ossifying hemangioma. However, reactive bone formation at the borders of a tumor in the internal auditory canal can also be mistaken as new intratumoral bone formation.

Obliteration of the frontal sinus--state of the art and reflections on new materials.

Despite increasing advances in endonasal frontal sinus surgery, obliteration of the frontal sinus is necessary in some cases for definitive clearing frontal sinus pathology. Reviewing the literature and considering pathophysiological aspects, successful obliteration of the frontal sinus depends on the complete removal of the mucosa and a sufficient closure of the nasofrontal duct, but not on the material used for obliteration, if special considerations are taken into account and foreign materials are avoided. Complete removal of the mucosa has to include removal of the inner bony cortex of the frontal bone. Occlusion of the nasofrontal duct is achieved with a sufficiently fixed fibrous layer.

Substituted tetrahydropyrrolo[2,1-b]oxazol-5(6H)-ones and tetrahydropyrrolo[2,1-b]thiazol-5(6H)-ones as hypoglycemic agents.

A series of substituted tetrahydropyrrolo[2,1-b]oxazol-5(6H)-ones and tetrahydropyrrolo[2,1-b]thiazol-5(6H)-ones was synthesized from amino alcohols or amino thiols and keto acids. A pharmacological model based on the results obtained with these compounds led to the synthesis and evaluation of a series of isoxazoles and other monocyclic compounds. These were evaluated for their ability to enhance glucose utilization in cultured L6 myocytes. The in vivo hypoglycemic efficacy and potency of these compounds were evaluated in a model of type 2 diabetes mellitus (non-insulin-dependent diabetes mellitus), the ob/ob mouse. 25a(2S) (SDZ PGU 693) was selected for further pharmacological studies.

[Jugulotympanic paraganglioma: therapy concepts under development]. / Jugulotympanale Paragangliome: Therapiekonzepte in der Entwicklung.

BACKGROUND: The operative treatment and radiation therapy of jugulotympanic paragangliomas (JTP) are still a matter of controversial discussion. In spite of various improvements during the last 50 years, selecting the appropriate treatment modality (surgery, radiation, or observation) is still a challenge. PATIENTS: During a 16-year period, 44 patients with 45 JTP (10 at level A/B and 35 at level C/D according to Fisch) were seen at the ENT-department in Fulda. Forty-one cases were treated surgically. RESULTS: Complete resection was possible for level A/B in 100% of the patients (n = 10). Residual tumor was demonstrated for level C in 23% of the patients (5/22) and for level D in 40% (4/10) with a median follow-up time of 69 months. In two cases residual tumor was treated by radiation. Six patients with residual paraganglioma tissue were maintained under observation without any evidence of tumor progression (median follow-up time 39 months). We report one death after the attempt to resect a large residual paraganglioma that had already caused brain stem compression. A sufficient duraplasty could not be achieved following radiation therapy. CONCLUSIONS: Complete tumor resection of jugulotympanic paragangliomas of levels A and B is often possible without injury to the cranial nerves. Extensive tumors present difficulties in complete tumor resection and increase the risk of cranial nerve injuries. Advanced paragangliomas therefore require an individualized therapeutic regime including surgery, radiation therapy, and observation of tumor growth.

[Experiences in diagnosis of occult traumatic dural lesions of the anterior cranial base]. / Erfahrungen in der Diagnostik okkulter traumatischer Duraläsionen der vorderen Schädelbasis.

BACKGROUND: Meningitis or cerebrospinal fluid rhinorrhea can occur years or even decades after trauma and can be the first indication of a previously unidentified dural lesion. In spite of being difficult, precise localization of an occult traumatic dural lesion is a necessary prerequisite for duraplasty. PATIENTS AND METHODS: In a retrospective study covering a period of 17 years, we identified 27 patients with occult traumatic dural lesions. The dural lesions were localized by high-resolution CT, MRI, fluorescein nasal endoscopy, and CT cisternography. In all cases the expected dural lesion was demonstrated and treated surgically. RESULTS: In 23 out of 27 patients (85%), the rhinobasal fistula was detected as a bony defect by CT. Furthermore MRI examination in 100% (5/5), a preoperative fluorescein nasal endoscopy in 50% (10/20) and CT cisternography in 56% (5/9) were able to localize the dural lesion. CONCLUSION: We recommend high-resolution CT and MRI as diagnostic tools of choice in searching for occult dural lesions. Fluorescein nasal endoscopy and CT cisternography are justified as invasive techniques if CT and MRI are inconclusive but clinically CSF leakage is still suggested. The patient will remain at risk of potentially fatal meningitis until the lesion is appropriately repaired by duraplasty. Therefore modern clinical and radiological diagnostic methods should be used to search for an unknown dural lesion.

Occult malformations of the skull base.

Occult malformations of the skull base are rare anomalies. They are often not detected until they give rise to complications such as meningitis or cerebrospinal fluid rhinorrhea. We used high-resolution computed tomography, fluorescein endoscopy, cisternography, magnetic resonance imaging, and duraplasty to diagnose occult malformations of the skull base in 4 patients. The four patients had had between 4 and 6 attacks of meningitis. Cerebrospinal fluid rhinorrhea was confirmed in 3 cases. The following occult malformations were found: (1) an encephalocele of the glabella/cribriform plate and a meningocele at the petrous bone apex, (2) a meningoencephalocele at the petrous bone apex, (3) dural lesions in the regions foramen rotundum/sphenoid sinus and frontal sinus/cribriform plate, and (4) a dural lesion of the sphenoid sinus. In patients presenting with recurrent meningitis, meningitis with isolation of upper airway pathogens, or cerebrospinal fluid rhinorrhea, modern diagnostic methods should be used to search for dural lesions. Diagnosis of an occult malformation makes it possible to perform the necessary surgical repair and thus prevent the further occurrence of potentially fatal episodes of meningitis.