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Biomedical subjects

W Hassler

Publications and source records attributed to W Hassler.

At least 55 records · Page 3Linked to original sources
PubMed1994

Microsurgical Removal of Olfactory Groove Meningiomas via the Pterional Approach.

Commonly used frontobasal approaches for microsurgical removal of olfactory groove meningiomas have certain disadvantages, such as late exposure of the neurovascular complex located dorsal to the tumor, namely, the internal carotid artery, middle cerebral artery, anterior cerebral artery, and the optic nerves. In addition, the frontal sinuses are frequently opened and there can be compression of the frontal lobes from significant spatula pressure. We report our experience with the pterional approach for these tumors in 28 patients. All patients presented with hyposmia/anosmia; 20 had personality changes and 8 had visual deficits. At surgery, after dissection of the sylvian fissure, the internal carotid artery, middle cerebral artery, anterior cerebral artery, and the homolateral optic nerve were exposed before removal of the posterior tumor parts. Reduction of focal pressure was achieved by removal of the contralateral tumor following partial resection of the falx and crista galli. Total tumor removal was obtained in all but 1 patient. One patient died of pulmonary embolism. The psychoorganic syndrome resolved in all but 1 patient; visual deficits improved in 6 patients. There were no postoperative infections. We consider the pterional approach to be superior to others for these lesions because it provides early exposure of the neurovascular complex, preservation of the frontal venous drainage, and avoidance of postoperative cerebrospinal fluid fistulae.

Journal Article↗
PubMed1994

Transconjunctival approach to a large cavernoma of the orbit.

Orbital tumors, particularly those within the retrobulbar space, are sometimes approached by neurosurgeons as well as by ophthalmic and by maxillofacial surgeons. There are numerous descriptions for the operative techniques applied in this area. Most lesions are attacked extracranially via a lateral orbitotomy or transcranially, with or without resection of the sphenoid bone or the orbital rim. Less traumatic approaches in patients harboring a tumor in this functionally and cosmetically important region, therefore, are desirable. We describe a microneurosurgical transconjunctival approach to a large retrobulbar cavernoma in a 59-year-old man. This technique has led to a very satisfactory result, and the operation can be performed without transient section of extraocular muscles in sections.

Conjunctiva↗
PubMed1994

Emergency ventriculostomy-experience with a new screw device: technical note.

Emergency situations, such as acute hydrocephalus or ventricular hemorrhage, require immediate and reliable treatment by ventriculostomy. The method used has to be standardized, applicable in a fast manner, and associated with only minimum risk of infection. We present a recently developed set for external ventriculostomy, which meets the above-standing requirements, and which consists of a screw with self-biting thread, a metal cannula, and a special screwdriver. Ventriculostomy can be performed easily within 2 minutes, and the system can be fixed rigidly to the skull of the patient for a period of up to several weeks. Exchange of the cannula is possible within 1 minute. The system has been used in 90 cases so far, with a rate of possible infection of 1.1%.

Adult↗
PubMed1993

Demonstration of giant MCA aneurysm by transcranial duplex sonography and color Doppler imaging.

Transcranial color Doppler sonography is a new diagnostic technique which allows real-time, color-coded imaging of basal cerebral arteries, with simultaneous demonstration of parenchymal structures in the B-mode scan. With this technique we were able noninvasively to show a giant fusiform aneurysm of the middle cerebral artery (MCA) in an 11-year-old boy. Transcranial color Doppler sonography through the intact temporal bone demonstrated the size and location of the aneurysm and provided real-time imaging of the pulsating intra-aneurysmal flow. Additionally, duplex sonographic measurements of intravascular flow velocities within the aneurysm and the feeding and draining artery were possible. Postoperatively, patency of the MCA with reduced flow velocities after excision of the aneurysm could be shown. This is the first transcranial color Doppler report in a patient with an intracerebral aneurysm. In our opinion, transcranial color Doppler sonography offers new diagnostic possibilities in patients with cerebrovascular disorders.

Blood Flow Velocity↗
PubMed1993

[Transcranial Doppler ultrasound in craniocerebral trauma: valuable method in traumatologic emergency cases?].

Introduction of the transcranial Doppler method 1982 (1) by Aaslid made it possible for the first time to monitor noninvasively the cerebral haemodynamics after severe head injury, or in polytraumatized patients in the emergency room. Mean flow velocities (FVmean) and systolic-diastolic frequency spectrum (PI) in basal cerebral arteries were considered. In that way, influences of different pathological intracerebral processes to cerebral haemodynamics are detectable earlier and triage planning of therapeutic steps is facilitated. The following haemodynamic changes are detectable: Increased intracranial vascular flow resistance due to raised intracranial pressure after SHI, hyperaemia due to short-term hypoxia or SHI, decreased intracerebral perfusion after ischaemia or beginning cerebral circulatory arrest, and increased flow velocities (FV) in case of traumatic A.V. fistulas or traumatic vasospasm. Primary experiences in patients with raised intracranial pressure were collected by Hassler, who found a correlation between characteristic Doppler flow signals in case of increasing intracranial pressure and circulatory arrest (Abb. 1). In case of space-occupying epidural, subdural or intracerebral bleedings or brain swelling, the average FV decreases and the pulsatility index increases as a sign of high flow resistance. In beginning of circulatory arrest, oscillating flow or systolic spikes are detectable. After resuscitation early posthypoxic flow acceleration is also visible immediately after admission to the emergency room. In case of ischaemia with detection of hypo-densities in CCT scan, flow velocities are decreased. Traumatic A.V fistulas, especially the carotid sinus cavernous fistula (CCSF), and the haemodynamic consequences to the circle of Willis are seen, a high mean flow velocity with increased end-diastolic flow at fistula sight being noticeable.2+ in the emergency room. If this is not possible, interpretation of flow signals and measured flow velocities can be only made by comparing both sides. All measurements should be made at normal mean arterial blood pressure. This method enables rapid orientation of intracerebral haemodynamics after SHI and facilitates the decision of what should be done first of all.

Adult↗
PubMed1992

Periventricular neurocytoma: a pathological entity.

Three cases of periventricular neurocytomas are presented. All patients had a large but well-circumscribed, hyperdense tumor with insignificant contrast enhancement in the lateral and third ventricle, causing hydrocephalus. Calcification was present in one patient. Angiography revealed a blush tumor enhancement in two cases. Surgical removal was complete in two patients and incomplete in one. Light microscopy showed a cell pattern that resembled either ependymoma or oligodendroglioma. However, in all cases the tumor was confirmed to be a neurocytoma by immunocytochemical analysis that showed reactivity for synaptophysin and/or neuron-specific enolase in a high percentage of neoplastic cells. With respect to the literature it is concluded that neurocytomas represent an individual pathological entity of supratentorial midline tumors. Complete surgical removal without irradiation is the recommended treatment.

Adult↗
PubMed1992

[Narrowing of the palpebral fissure as the first symptom of extensive osteoma with orbital involvement].

Unilateral narrowing of palpebral fissure and moderately impaired visual acuity induced a 14 years old woman to consult an ophthalmologist. Neuroradiological examination revealed a large osteoma starting from the ethmoid cells and invading both the orbit and the cranial cavity. This case illustrates that proptosis may be absent even in cases of extensive and compact orbital tumors. Therefore, exophthalmos is a common but not an indispensable sign of an orbital tumor. In Gardner's syndrome osteomas are associated with soft tissue tumors, intestinal polyposis and colonic adenomatosis that ultimately progresses to colorectal cancer. This association is frequent enough that a colon examination should be suggested to all patients with osteoma.

Adolescent↗
PubMed1991

Investigations on oscillating flow spectra as a Doppler ultrasonographic sign of intracranial circulatory arrest.

In a total of 90 patients with intracranial hypertension and subsequent intracranial circulatory arrest, the cerebral basal arteries were examined with transcranial Doppler ultrasonography. In order to explain the development of the various forms of oscillating flow, a blood-pressure cuff was placed on the distal forearm of 25 healthy subjects to investigate the flow spectra in the proximal arteries in the presence of increasing stream resistance. With raising the pressure of the cuff, the changes in the Doppler sonographic flow spectra were simulated as in case of increasing intracranial pressure. As intracranial pressure increases at constant systemic blood pressure values, the flow velocity spectrum changes in a typical manner. At the stage of oscillating flow, characteristic changes in the flow spectra can be observed. Investigations showed that compliance is reduced in a distal to proximal direction. This means that a different frequency spectrum can be recorded in distal branches of the middle cerebral artery than in the proximal carotid artery at the same point in time. By examining the flow velocity spectra from the brachial artery, it was possible to understand better the typical course of an intracranial circulatory arrest resulting from increased stream resistance.

Adolescent↗
PubMed1991

A wooden foreign body penetrating the superior orbital fissure.

The case of a 12-year-old patient with a wooden foreign body which had penetrated the superior orbital fissure is presented. Using a transethmoidal approach, only some splinters lying in the periorbital soft tissue were removed. The patient became febrile, indicating an infectious complication due to a retained foreign body. This was confirmed by CT scan and MRI demonstrating a main splinter in the superior orbital fissure. Total removal of the wood was achieved via a pterional extradural approach. The difficulties of identifying wooden foreign bodies as well as the topographical problems involved with the approach to the superior orbital fissure are discussed.

Bicycling↗
PubMed1991

Prevention of an air embolism by moderate hypoventilation during surgery in the sitting position.

The effect of ventilation (normo-, hypo-, and hyperventilation) on transverse sinus pressure (TSP), central venous pressure (CVP), mean arterial blood pressure (mABP), and heart rate was studied in 15 patients undergoing neurosurgical treatment in the sitting position for tumors of the posterior fossa, and the findings were compared with the influence of positive end expiratory pressure (PEEP) on these parameters. TSP was not influenced significantly by PEEP ranging from 0 to 15 mbar, whereas CVP increased. At the same time, mABP decreased slightly. In contrast, TSP showed characteristic changes with varying ventilation: during normoventilation [end expiratory CO2 pressure (PECO2), 38 mm Hg], TSP was 3 mm Hg and increased to 7 mm Hg on average with hypoventilation (PECO2, 44 mm Hg), whereas hyperventilation (PECO2, 32 mm Hg) caused a reduction in TSP to the atmospheric range. At the same time, CVP remained unchanged, whereas mABP increased with hypoventilation. Presuming that the risk of venous air embolism is closely related to the level of TSP, our results allow the following conclusions. 1) PEEP does not seem to be effective in preventing venous air embolism. 2) Hyperventilation is dangerous in the sitting position, as TSP is reduced to the atmospheric and even subatmospheric range. 3) To prevent air embolism, moderate hypoventilation is recommended during the most critical period of exposing the posterior fossa followed by normoventilation when surgery of the actual lesion has begun.

Aged↗
PubMed1991

Surgical treatment of olfactory groove meningiomas using the pterional approach.

We present our experience with the surgical treatment of olfactory groove meningiomas using a pterional approach. This approach provides the advantages of previous techniques, such as preserving the frontal brain and superior sagittal sinus, early devascularization of the tumour, and late dessection of tumour borders. Moreover, it also compensates for the shortcomings of other techniques, e.g., compression of frontal bridging veins, late dissection of dorsal tumour aspects involving vessels and optic nerves as well as facultative infection and cerebrospinal fluid fistula-related complications caused by opening of frontal sinuses. To date, 11 patients were treated in this way. As we encountered no surgical complications in our series we are encouraged to present our procedure.

Adult↗
PubMed1990

Radical osteoclastic craniectomy in sagittal synostosis.

We report our experience in the surgical treatment of sagittal synostosis using radical osteoclastic craniectomy in 60 consecutive patients. After surgery in children aged 6 months or younger (Group I), reossification usually started 2 weeks postoperatively and was complete within 6 months, resulting in an optimal skull contour. In children aged 7 to 12 months (Group II), reossification was prolonged and lasted for 12 months or longer. The skull contour normalized in its biparietal width and improved in sagittal diameter, remaining, however, slightly abnormal. In children older than 12 months (Group III), the skull contour partly improved in the biparietal diameter but did not change in the sagittal direction. Reossification was incomplete with persistent pseudosutures. Enlarged frontal subarachnoid spaces were reversible or improved in all patients independent of age at the time of surgery. We encountered no complications in our series. In our opinion, radical osteoclastic craniectomy is the simplest, most efficient, and most physiologically sound method for the treatment of sagittal synostosis in patients up to 6 months of age. This procedure allows the rapidly growing brain to form its skull vault, thus providing optimal cosmetic results. In older children, osteoplastic morcellation procedures should be the treatment of choice.

Craniosynostoses↗
PubMed1989

Cavernous angioma of the optic tract.

A cavernous angioma of the right optic tract in a 35-year-old man is presented. The patient suffered from headaches and had a left homonymous visual field defect after subarachnoid haemorrhage and an intracerebral haematoma in the right temporomedial region, revealed by computed tomography (CT). Follow-up CT showed a small contrast-enhanced lesion in the right suprasellar and parasellar cistern. Angiography on three occasions did not reveal a vascular lesion. Magnetic resonance imaging was helpful both for diagnosis and planning surgical therapy. It showed typical signs of a cavernous angioma of the right optic tract; the diagnosis was confirmed by surgery and histological examination. This appears to be the first reported case of a cavernous angioma of the optic tract.

Adult↗
PubMed1989

Abnormal origin of the ophthalmic artery from the anterior cerebral artery: neuroradiological and intraoperative findings.

A 7-year old male child with an abnormal ophthalmic artery arising from the A1 segment of the anterior cerebral artery is described. The patient suffered growth inhibition which was thought to be caused by a craniobasal cystic lesion affecting the hypothalamus. Preoperative angiograms revealed no vascular abnormalities. The right ophthalmic artery, however, could not be identified. During resection of a large arachnoid cyst the ophthalmic artery was found to arise from the A1 segment of the anterior cerebral artery. To the best of our knowledge, this exact anomaly has not previously been reported. The clinical, neuroradiological and intraoperative findings are presented.

Arachnoid↗
PubMed1989

On the haemodynamics of arteriovenous fistulas in the rat.

Direct and indirect arteriovenous fistulas were applied to the cervical vessels of 19 rats in order to study the haemodynamic parameters of angioma-like, rapid blood flow in small vessels. Flow was measured electromagnetically and intraoperatively using the Doppler sonography, and both methods were compared. Resultant alterations in vessel walls were examined under the electron microscope. Following fistula application, the flow rates increased by a factor of ten. At the same time, the flow pattern profile and stream resistance also changed. At present, the Doppler sonography device employed here is the only one commercially available, yet it could not detect rapid flow rates (greater than 85 cm/sec). The abnormal haemodynamic strain on the venous walls led to morphologically and angiographically detectable alterations.

Animals↗
PubMed1989

CO2 reactivity of cerebral vasospasm after aneurysmal subarachnoid haemorrhage.

CO2 reactivity of the brain vessels was investigated in 33 patients (Grade I-III after Hunt and Hess) with cerebral vasospasm after an aneurysmal subarachnoid haemorrhage (SAH) and after early operation within 72 hours. In all cases, transcranial Doppler sonography was used to measure flow velocities in the middle cerebral artery (MCA) and internal carotid artery (ICA) and vasomotor reactivity to CO2 changes. Vasospastic conditions lead to higher flow velocities through the narrow segment, lower peripheral stream resistance due to the post-stenotic pressure drop and lower vasodilating capacities of arterioles under hypercapnia. In severe vasospastic conditions, the peripheral stream bed is already maximally dilated and the hypercapnic response is weak. On the other hand, the peripheral vascular bed reacts normally to hypocapnia in all vasospastic situations. Our results point out two dangerous conditions of vasospastic disease: 1) exhaustion of peripheral vasodilating capacities, and 2) hyperventilatory therapy. Both of these situations can result in a reduction of CBF to brain tissue, mainly for two reasons: 1) In the former, a further increase in vasospasm cannot be compensated for anymore when the peripheral arterioles are maximally dilated, and 2) in the latter, hypocapnia produces a strong peripheral vasoconstrictor response with further reduction of CBF.

Blood Flow Velocity↗