[Palliative treatment of brain metastases with gamma knife]. / Palliative Behandlung von Hirnmetastasen mit dem Gamma Knife.

The gamma knife is a stereotactic radiosurgery device which allows well defined, deep seated brain tumors or arteriovenous malformations with a maximal volume of about 25 ccm and a diameter not greater than 3.5 cm, to be treated in a single session under local anesthesia. The gamma knife offers an alternative treatment method to the classical approach of treating brain metastases by surgical excision and/or whole brain radiotherapy. The advantages of this technique are evident: the method is non-invasive, the treatment is carried out in a single session with a very short hospitalisation of two to three days, it is exempt from physical and psychical stress, the head does not need to be shaved and no hair loss occurs, a good quality of life is obtained for a reasonably prolonged survival time and it offers an economically favourable treatment method. Up to December 1999, over 30,000 patients suffering from brain metastases have been treated worldwide using the gamma knife. In Zürich, from September 1994 to December 2000 140 received this treatment. In the literature selection criteria may differ, and this may have determined some of differences in outcome. However, our results are comparable with those in the majority of publications with an average survival time of 263 days and a maximum survival of 1080 days. Good prognostic factors for survival and local control of brain metastases are a Karnofsky Performance Scale Score approaching 90 to 100, but not lower than 70, tumour volume, controlled primary cancer, and absence or stable extracranial metastases.

Octreotide may act as a radioprotective agent in acromegaly.

Clinical experience shows that an increasing number of patients undergoing radiation treatment for recurring acromegaly or acromegaly persisting after surgery are treated with octreotide. We, therefore, performed a follow-up study of patients undergoing stereotactic radiosurgery (Gamma Knife) to determine whether this medication has an influence on the ultimate result of radiation therapy in either a positive or negative sense. It has been suggested that the combination of radiation with antisecretory drugs may increase the effectiveness of radiation. A follow-up study of 31 patients suffering from recurrent acromegaly and acromegaly persisting after surgery, and who had been treated with stereotactic radiosurgery, showed that patients treated with octreotide at the time of radiation application simultaneously reached a normal level of growth hormone and insulin-like growth factor-I only after a significantly longer interval than patients who did not receive the drug. The two groups of patients did not demonstrate significant differences in the main clinical findings (age, sex, target volume, radiation dose, baseline growth hormone, and baseline insulin-like growth factor-I).

Stereotactic radiosurgery for recurrent surgically treated acromegaly: comparison with fractionated radiotherapy.

OBJECT: The authors tested the assumption that gamma knife radiosurgery is more effective than fractionated radiotherapy for the treatment of patients with acromegaly who have undergone unsuccessful resective surgery. Untreated and uncured acromegaly causes illness and death. Acromegalic patients in whom growth hormone and, particularly, insulin-like growth factor I are not normalized must undergo further treatment. METHODS: After unsuccessful operations, 16 patients suffering from recurrent and uncured acromegaly underwent stereotactic radiosurgery (25 Gy to the tumor margin, 50 Gy maximum), the outcome of which was compared with the result obtained in 50 patients who received fractionated radiotherapy (40 Gy). The cumulative distribution functions of the two groups (Kaplan-Meier estimate) differed significantly (p < 0.0001 in the log-rank test of Mantel). The mean time to simultaneous normalization of both parameters was 1.4 years in the group treated with the gamma knife and 7.1 years in the group treated with fractionated radiotherapy. CONCLUSIONS: The authors suggest the use of stereotactic radiosurgery as the preferred treatment for recurrent acromegaly resulting from unsuccessfully resected tumors.

[Gamma knife radiosurgery in neurosurgery]. / Das Gamma-Knife im Dienste der Neurochirurgie.

The gamma knife is a stereotactic radiosurgery device which allows well defined, deep seated brain tumors, or arteriovenous malformations having a diameter of less than 3 cm, to be treated in a single session under local anesthesia. This technique, which was first described over 40 years ago, has undergone major development in recent years and is the most commonly used method for radiosurgery worldwide. The principle relies on the over-lapping of narrow collimated beams from 201 cobalt-60 sources. The technique, which was introduced into Switzerland in September 1994, has rapidly gained recognition. 184 patients have been treated by 30 April 1997. An average follow-up period of 15 months is much too short for analysis of patients treated by radiosurgery. However, our series of benign tumors shows stabilization of volume in the first few months followed by a slow reduction of the tumor volume, in all but two cases. The gamma knife represents the treatment of choice for recurrent and unsuccessfully operated patients with endocrine active pituitary adenomas. With brain metastases, a rapid reduction in tumor volume is seen in the first few weeks in the majority of cases. The tumor volume may then remain stable or reduce further until complete disappearance. In the case of arteriovenous malformations complete obliteration of the nidus is not seen, on average, for 2-3 years. Individual patient follow-up studies illustrate these results. To date our results have shown zero morbidity and mortality. International statistics from 58,766 cases (as of December 1996) from 77 gamma knife centers demonstrate the value of this technique as a complement or, depending on the indication, an alternative to classical microsurgery.

The value of inferior petrosal sinus sampling in diagnosis and treatment of Cushing's disease.

OBJECTIVE: While microsurgical selective adenomectomy is the best method available at present for the treatment of Cushing's disease, its success depends to a large degree on precise preoperative intrapituitary microadenoma localization. This study compares the results of intrapituitary adenoma localization obtained with inferior petrosal sampling, computerized tomography and magnetic resonance imaging with the adenoma localization as found at surgery. DESIGN: The results of inferior petrosal sampling for intrapituitary localization of ACTH-producing pituitary adenomas were compared in a retrospective study with the results of computerized tomography, magnetic resonance imaging, surgical and pathological findings. Special attention was paid to the intersinus ACTH relation. PATIENTS: Thirty-eight patients (33 women and 5 men) of 11-68 years of age suffering from pituitary-dependent Cushing's disease were studied. Patients with ectopic ACTH-secreting tumours and recurrent pituitary adenomas were excluded. MEASUREMENTS: Blood samples were obtained simultaneously from both inferior petrosal sinuses and a peripheral vein before and 5, 10, 15 and 20 minutes after stimulation with 60 micrograms/m2 human corticotrophin-releasing hormone (hCRH). RESULTS: Of the adenomas in our series, 42% had a diameter of 3 mm or less. Only 6 of 20 adenomas examined by computerized tomography and 11 of 29 examined by magnetic resonance imaging were identified correctly. Inferior petrosal sinus sampling produced significantly better results, particularly when combined with a stimulation test with hCRH: for 29 of 38 adenomas examined, the location was predicted correctly with these techniques. Analysis of the intersinus adrenocorticotrophin concentration ratio showed that the best right-central-left discrimination was obtained with values of 1.3 and 1.4. CONCLUSIONS: We conclude that inferior petrosal sinus ACTH sampling after hCRH stimulation is the best method available for the intrapituitary localization of microadenomas causing Cushing's disease provided that the appropriate technique of blood sampling is used meticulously.

Metastases to the pituitary--hypothalamic axis. An MR study of 7 symptomatic patients.

Seven patients with metastatic tumour in the pituitary-hypothalamic axis were investigated by MRI. The main clinical problems were diabetes insipidus (5 cases) and general pituitary dysfunction (2 cases). No patient had visual or oculomotor symptoms. In 6 of the 7 patients the primary malignant tumour was known, but no patient had symptoms from the primary tumour; 1 had symptoms from metastases in locations other than the pituitary gland. In one patient no primary tumour was known. MR detection of a second, clinically silent, 5 mm lesion in the posterior cranial fossa initiated the search for primary tumour. MRI showed purely suprasellar tumours in 3 patients and intra- and suprasellar tumours in 4. The latter were dumbbell lesions with only a small bridge of tissue connecting the intra- und suprasellar portions. Six of the 7 suprasellar tumours seemed to be in the infundibular recess of the third ventricle; in 5 the infundibulum was visible as an enhancing linear structure at the postero-inferior border of the tumour. The pituitary fossa was normal in all cases.

Neuroradiology of central neurocytoma.

Central neurocytomas (CN) are rare, usually benign cerebral intraventricular neuroepithelial tumors, which occur in adult patients. Retrospective evaluation of the CT- and MRI-findings in eight cases as well as review of the cases reported in the literature showed that CN usually presents as a primarily slightly hyperdense and/or hyperintense mass within the body of the lateral ventricle with moderate contrast enhancement. The majority of tumors contain both multiple small cysts and calcifications and exhibit a characteristic broad based attachment to the superolateral ventricular wall. We conclude that these criteria appear to be reliable to exclude other intraventricular tumors such as astrocytoma, giant cell astrocytoma, ependymoma, subependymoma, intraventricular oligodendroglioma and meningioma. Preoperative diagnosis of CN may prove of value for planning therapy, because this tumor type seems to have a better prognosis than other intraventricular tumors.

[NMR tomographic diagnosis of microadenomas of the hypophysis: a comparison of MRT, CT and operation]. / Zur kernspintomographischen Diagnostik von Mikroadenomen der Hypophyse: Vergleich MRT, CT und OP.

The MR and CT findings of 24 surgically verified cases with clinical and neuroradiological evidence for pituitary microadenomas were compared. In 18 patients the preoperative diagnosis was surgically confirmed. In 6 cases the preoperative diagnosis proved to be wrong at operation. In 18 cases with confirmed diagnosis MR proved more sensitive than CT, whereas in the 6 cases with wrong diagnosis both methods proved to be of equal sensitivity. It is concluded that MR is superior to CT for the evaluation of pituitary microadenomas, provided that high-field and special examination techniques including thin, overlapping sections and enhancement with GD-DTPA are used.

[Localization of small subcortical processes in important functional zones by preoperative x-ray computed tomography]. / Localisation de petits processus sous-corticaux situés au niveau de zones fonctionnelles importantes par tomodensitométrie préopératoire.

Operative approach the subcortical lesions in a functionally important region must be small, sure and sparing, thus requiring an exact preoperative localization. This is possible by using a little ringshaped cooperwire, which does not produce artefacts on computerized tomographs and, by measuring distances between this cooperwire and the focal lesion.

Growth-mechanism of giant intracranial aneurysms; demonstration by CT and MR imaging.

In four cases of giant intracranial aneurysm, CT demonstrated a hyperdense open-, or closed-ring structure at the periphery of the aneurysm. Surgery in two of the cases demonstrated that this peripheral hyperdensity represents fresh clot inside the wall of the thrombosed mass. An analogy is established between giant intracranial aneurysms, chronic subdural hematomas and growing encapsulated intracerebral hematomas. The common feature of the three entities is slow growth by recurrent hemorrhages into the lesion. It is proven that growth of chronic subdural hematomas and of growing encapsulated hematomas is related to recurrent hemorrhage from capillaries sprouting within the membrane of the lesion. The highly vascularized membranous wall of a giant intracranial aneurysm seems to behave like the membrane of a chronic subdural hematoma. It is suggested that the giant intracranial aneurysm grows by recurrent hemorrhage into its wall and behaves like growing encapsulated hematomas.

[CT diagnosis of traumatic injuries of the temporal bone]. / CT-Diagnostik traumatischer Läsionen des Felsenbeines.

73 patients with 78 fractures of the temporal bone were examined by high-resolution computed tomography (CT). Analysis of the CT-findings disclosed 55 longitudinal, 12 transverse, 8 combined and 3 atypical fractures. For determination of the fracture type, axial sections usually proved sufficient. However, for precise topographic analysis of the course of the fracture additional coronal sections were necessary in most of the cases. In the radiologic evaluation of temporal bone fractures detection of associated complications is clinically important since these can be surgically corrected. In this series 20 lesions of the ossicular chain were demonstrated by the combined performance of axial and coronal sections and sagittal reformations. High resolution CT demonstrated a lesion of the facial nerve canal in 79% of a patient group with traumatic facial nerve palsy. The most frequent site of injury of the facial nerve canal was the region of the geniculate ganglion. With the use of metrizamide-CT-cisternography the site of cerebrospinal fluid leakage was demonstrated in 7 of 9 patients with liquorrhea. It is concluded that high-resolution CT is the radiologic method of choice for both topographic evaluation of temporal bone fractures and detection and precise localization of fracture-complications.

Classification of brain arteriovenous malformation nidus by magnetic resonance imaging.

T1 and T2 weighted high field magnetic resonance imaging (MRI), computed tomography (CT) and intraarterial digital subtraction angiography (DSA) were performed in 30 patients with brain arteriovenous malformations. T2 weighted MR sequences proved superior to both CT and intraarterial DSA for displaying the configuration of the nidus, its intrinsic morphology and the state of the surrounding parenchyma. As was evidenced by histologic examination of the nidus in 18 cases, high-signal intensity of the intervening or surrounding parenchyma on T2 weighted images indicates gliosis. Preliminary experience with 5 cases suggests that gliosis of the intervening or surrounding brain parenchyma may make it safer to attempt embolization in these patients. Based on these parameters, we introduce a classification of brain AVM nidus.

Temporal bone fractures and their complications. Examination with high resolution CT.

A total of 84 patients with 89 fractures of the temporal bone were examined with high resolution CT (HRCT) a few hours to 21 months after the initial trauma. Axial HRCT disclosed 63 longitudinal, 13 transverse, 10 complex and 3 atypical fractures. The diagnosis of a temporal bone fracture was established by axial HRCT in almost every case. However, for the precise topographic analysis of the course of the fracture, additional coronal HRCT proved helpful. The most common, surgically treatable complication of temporal bone fracture is disruption of the ossicular chain. Twenty-three such lesions were demonstrated by combined axial and coronal HRCT; 22 lesions of the facial canal could be demonstrated in 27 patients presenting with facial nerve palsy. The most common site of injury to the facial canal was the region of the geniculate ganglion. The only life-threatening complication of a temporal fracture may be otorhinoliquorrhea. This was present in 9 cases. The most common site of leakage identified was the tegmen tympani. With Metrizamide-HRCT precise localisation of the dural laceration was possible in 7 of these 9 cases.

[Indications for and significance of computerized tomographic studies in radicular syndromes]. / Indikationen und Aussagekraft der computertomographischen Untersuchung bei radikulären Syndromen.

Radicular symptoms are produced by disc herniations or spinal stenoses, causing compression of the exiting nerve roots. For radiologic evaluation of lumbar radicular symptoms, computed tomography has the same diagnostic accuracy as myelography and therefore is the diagnostic modality of choice. In cases of recurrent radicular symptoms after operation for disc herniation, computed tomography is superior to myelography for differentiation between recurrent disc herniation and hypertrophic scar formation. Cervical computed tomography is less accurate for detection of cervical disc herniations, because the shoulders regularly produce severe artifacts at deeper levels C 6/7 and C 7/D1. For this reason, computed tomography is only recommended for diagnostic workup of cervical disc herniations at levels higher than C 6/7.