Biomedical subjects

H G Boecher-Schwarz

Publications and source records attributed to H G Boecher-Schwarz.

9 recordsLinked to original sources

PubMed2000

Ex vivo study of the physical effect of coils on pressure and flow dynamics in experimental aneurysms.

BACKGROUND AND PURPOSE: Recent experimental studies and a few case reports reveal that coiling may not lead to permanent occlusion of aneurysms by an organized thrombus. Therefore, biologic long-term prognosis seems to be doubtful, and the physical effect of coils may be important. The purpose of this study was to investigate the physical effect of coils on pressure and flow dynamics in aneurysms. METHODS: Bifurcation aneurysms were created in eight rabbits, explanted after 3 weeks, and tested in a model with pulsatile perfusion with 0.9% saline and heparinized blood. Before and after densely packing with coils, systemic and intraaneurysmal pressure, aneurysmal pulsation, and impact measurements were recorded. RESULTS: The peak and shape of the pressure waves in the aneurysm and in the delivery system were not significantly different before and after coiling. Under physiological intraaneurysmal pressure (while being perfused with saline), significant reduction (P = .022) of aneurysmal wall pulsation after coil embolization was noted. Overall, the aneurysmal impact on surrounding structures was statistically unchanged after coiling. However, in a few cases, after coil embolization, the observed increase of impact was more than doubled compared with the original values before coiling. CONCLUSION: Coils do not physically affect intraaneurysmal pressure. After coiling, there is no significant reduction of flow rates through the aneurysm and no reduction of aneurysmal impact, but aneurysmal wall pulsation may be decreased.

Animals↗

PubMed1998

Sensitivity and specificity of MRA in the diagnosis of neurovascular compression in patients with trigeminal neuralgia. A correlation of MRA and surgical findings.

The published rates of operatively confirmed neurovascular compression as the cause for trigeminal neuralgia range from 10% to nearly 100%. High-definition magnetic resonance angiography (MRA) was performed in 27 consecutive patients (in 6 cases with 3D reconstructions) to show neurovascular compression preoperatively. The MRA findings were compared with the relationship between the Vth nerve and the surrounding vessels at surgery. In 23 patients MRA showed present neurovascular compression in accordance with surgical findings (18/27 in complete accordance of type and side of vessel, site and direction of compression). One woman had no neurovascular compression either on MRA or intraoperatively. One MRA prediction of neurovascular compression was false, and two results were false negative. The sensitivity of MRA was therefore 88.5% but the specificity only 50%, if surgical findings are the reference. In one patient with right trigeminal neuralgia MRA revealed bilateral neurovascular compression of the Vth nerves. Therefore, the overall specificity of MRA might be below 50%. In one patient with multiple sclerosis, the decision to operate was markedly influenced by the clear finding of neurovascular compression on MRA. The patient has been free from trigeminal pain for 149 weeks after microvascular decompression. In 6 patients, 3D reconstructions of the MRA data were performed. The images helped in 3D visualisation of the operation, but did not yield new information about the nature of the vessels revealed, or the site, direction or side of the neurovascular compression.

Cerebellopontine Angle↗

PubMed1998

Cerebral blood flow velocities after subarachnoid haemorrhage in relation to the amount of blood clots in the initial computed tomography.

In 72 patients with acute subarachnoid haemorrhage (SAH) the relationship between the amount of subarachnoid blood clots detected by initial cranial computed tomography (CCT) up to 48 hours after bleeding and the later development of vasospasm, established by blood flow velocity measurement with transcranial Doppler ultrasound (TCD) was investigated. The serial Doppler examinations started within the first 72 hours after SAH and were carried out every second day up to three weeks. Each Doppler recording was accompanied by a neurological examination. Patients classified as Hunt and Hess grade V were excluded from the study. All patients with remarkable brain oedema in CCT or with intracranial pressure above 25 mmHg were also excluded. Because of the well known age-dependence of vasospasm after SAH, two age groups were formed. A statistically significant correlation (p > 0.05) between blood flow velocities and blood load after SAH was not found. The mean age of the investigated 72 individuals was 48.9 years (14 up to 76 years). 47 patients were younger than 56 years. Linear regression analysis indicated a correlation with a quite low significance level (r = 0.350, p < 0.025) between TCD blood flow velocities and blood load in CCT in these younger subjects. No significant correlation (p > 0.05) between these two variables could be established in the 25 patients older than 55 years. In a second step an intra-individual comparison of side-to-side differences in TCD and CCT was made. There were no significant differences in blood flow velocities between subjects with or without side-to-side differences in cisternal blood load. It is concluded that the amount of blood visible on initial CCT after SAH is not a powerful predictor of cerebral blood flow velocities measured by TCD.

Adolescent↗

PubMed1998

Endoscope-assisted microsurgery for cerebral aneurysms.

A total of 66 patients with intracranial aneurysms were endoscopically assisted treated during a 3 years period. Among those were five individuals with giant aneurysms and 27 patients with aneurysms of the posterior circulation. The endoscope was used only for checking the anatomical structures surround the aneurysms in 16 cases. In 43 patients the aneurysm sac was also dissected under endoscopical control. Even the clipping procedure was performed in seven cases exclusively under endoscopical observation. Only one prematural rupture occurred intraoperatively during preparation of a basilar tip aneurysm. Postoperatively three individuals with aneurysms located in the posterior circulation were temporarily neurologically impaired, and one patient with a basilar tip aneurysm suffered from a surgical related hemiparesis. The use of an endoscope in aneurysm surgery improves the visualization of the aneurysm itself and the surrounding anatomical structures. This minimizes the retraction of the nervous structures and leads to a reduced morbidity.

Endoscopy↗

PubMed1996

Stereotactically guided cavernous malformation surgery.

The incidence of a significant hemorrhage in the natural history of cavernomas is below 1% per year, but the risk of a second hemorrhage in patients with initial bleeding cavernomas is between 14% and 29%. In the light of these figures, all cavernomas ought to be resected if surgical-related morbidity can be minimized. Stereotactically guided neurosurgery offers the advantage of planning the least traumatic approach before craniotomy due to the knowledge of the exact localisation of the lesion. During a 2-year period 12 patients (age 16-54 years) with intracranial supratentorial cavernomas (size 0.5-1.8 cm) were treated by stereotactically guided microsurgery. The cavernomas were seated in a depth between 0.4 and 4.5 cm. 4 patients had an overt hemorrhage in their history. In six cases a seizure was the first symptom (altogether 8 patients had seizures preoperatively). Two patients were asymptomatic. Standard CRW (Cosman, Roberts, Wells) stereotactic system was used in all cases. The skin incision and the osteoplastic craniotomy (mean diameter 2.8 cm) were planned stereotactically. In 11 patients a transsulcal approach was used. The size of the corticotomy could be limited to less than 1 cm. Using the stereotactic method, all cavernomas were found with a high degree of accuracy. After lesionectomy a total of 1 to 2 mm of the surrounding yellow-stained brain tissue was sucked away because it contains hemosiderin and therefore iron, which may have an epileptogenic effect. No relevant surgical-related neurological morbidity was found in any patient a half year after surgery. Seven out of eight patients were free of seizures. One still had problems.

Adolescent↗

PubMed1995

Pre- and intraoperative methods of controlling cerebral circulation in giant aneurysm surgery.

The surgical treatment of giant aneurysms usually requires temporary clipping of the aneurysmatic vessel. In planning the surgical approach and in applying temporary clips, the surgeon must consider collateral circulations. The functional integrity of the collateral vessels frequently decides the patient's outcome. In 8 patients with internal carotid artery giant aneurysm, measurements of blood flow velocities in the ipsilateral middle cerebral artery were performed preoperatively with transcranial Doppler ultrasound (TCD) during manual occlusion of the carotid artery at the neck. Three different perfusion patterns were established, and each collateral capacity was rated as insufficient, temporarily sufficient, or long-term unproblematic. Surgical strategies were conceived. In one patient with giant aneurysm of the middle cerebral artery the temporary occlusion test was not carried out preoperatively. Intraoperatively, collateral circulation was controlled using microvascular Doppler sonography (MVD). In 8 cases cortical blood flow (CoBF) was monitored by thermal diffusion flow probe and/or laser Doppler. In some cases, the complex pathological anatomy required a change in surgical strategy and a new MVD determination of collateral capacity. Despite these precautions 2 patients suffered ischemia of the basal ganglia and the white matter.

Adult↗

PubMed1994

Transcranial Doppler diagnosis of cerebral vasospasm following subarachnoid haemorrhage: correlation and analysis of results in relation to the age of patients.

A retrospective analysis was undertaken to determine whether cerebral vasospasm following subarachnoid haemorrhage (SAH) correlates with the age of patients. For at least 3 weeks after bleeding 80 subjects underwent very close follow-up with clinical examination and transcranial Doppler records of the blood velocities within the basal cerebral arteries. Firstly a correlation between measured maximal mean blood flow velocities and age was made. Secondly, according to their age and the maximum of recorded mean velocities (v), the patients were divided into groups as follows: age 55 years or less, age more than 55 years; and maximum velocity v1 < 90 cm/s, 90 cm/s < v2 < 120 cm/s, 120 cm/s < v3 < 160 cm/s, v4 > 160 cm/s. There was a significant correlation of the measured maximum mean velocities and the age of the patients (r = -0.525, p < 0.01). With regard to the velocity groups there was a significant (chi-squared statistic for contingency tables, p < 0.01) difference between both age-groups: 32% (n = 18) of the younger fell into group v4 with maximum mean velocities of more than 160 cm/s, but none of the older had such. Vice versa, 63% (n = 15) of the older compared with only 14% (n = 8) of the younger fell into group v1 with maximum mean velocities of less than 90 cm/s. Clinical follow-up also depicted differences between both age groups. 13 of 18 younger patients with maximum mean velocities > 160 cm/s exhibited symptomatic vasospasm with a delayed neurological deficit. This typical course did not occur in the older age group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

Suprasellar granular cell tumor.

A case of a suprasellar granular cell tumor, approximately 1.5 cm in diameter, in a 68-year-old woman is described. Diagnosis was established postoperatively by histopathological examination of the tumor tissue. The preoperative computed tomographic scan revealed a slightly hyperdense suprasellar mass with strong contrast enhancement. There was no evidence of calcification. The T1-weighted image on magnetic resonance imaging scan showed an isointense tumor with non-homogeneous enhancement after intravenous gadolinium diethylene-triamine-pentaacetic acid. In the proton-weighted image, the suprasellar mass presented a non-homogeneously enhanced signal. A non-homogeneous signal reduction was seen in the T2-weighted image.

Aged↗

PubMed1991

Intrasellar cysticercosis mimicking a pituitary adenoma.

A case of a 50-year-old female with an intrasellar and suprasellar cysticercus cyst, which was pre-operatively misinterpreted as a macroadenoma of the adenohypophysis is described. Cranial computed tomography revealed a homogeneous hyperdense intrasellar and suprasellar lesion. In T1-weighted magnetic resonance images, a spotty hyperintense tumor of the sellar region was shown.

Adenoma↗