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Biomedical subjects

C Schaller

Publications and source records attributed to C Schaller.

53 records · Page 3Linked to original sources
PubMed1996

[Differential therapy of cerebral arteriovenous malformations. An analysis with reference to personal microsurgery experiences].

A total of 126 patients (63 female, 63 male) underwent microsurgical removal of their cerebral arteriovenous malformations (AVMs) by the same surgeon. The mean age at surgery was 34.7 (6-72) years. The symptoms were intracerebral hemorrhage (37.3%), seizure disorder (34.9%) or focal neurological deficits and minor symptoms. According to the Spetzler/Martin scale, 20.6% of the AVMs were grade I, 28.6% grade II, 32.5% grade III, 14.3% grade IV and 4% grade V. In all, 78 AVMs (61.9%) were located in functionally important brain regions. The series was split into three different groups: small AVMs under 3 cm in diameter (n = 62/49.2%), medium-sized AVMs (n = 58/46%) and large AVMs (n = 6/4.8%). Seventeen patients had preoperative embolization of their AVM. All patients had postoperative angiographic control and 3- and 6-month follow-up. One patient died (0.8%), and another one (0.8%), in whom the AVM was incompletely resected, suffered a secondary hemorrhage. Seventeen (27.4%) of the patients with small AVMs developed transient neurological worsening post-operatively, which remained permanently significant in 3.2%. The respective numbers for the patients with medium-sized AVMs were 48.3% and 10.3% and for the large AVMs 83.3% and 33.3%. The results of microsurgical removal of cerebral AVMs can still be considered superior to the results of stereotactic radiosurgical treatment available from the literature-even for small AVMs. This is due to immediate exclusion of the AVM under direct local control of the angioarchitecture and thereby a reduced risk of secondary hemorrhaging and a decreasing morbidity rate with increasing time after the operation. Radiosurgical treatment requires a 2-year latency period for obliteration and carries a mortality rate of up to 12.5% and a rate of unexpected side effects of up to 20%. This treatment should be reserved for small, deep, surgically inaccessible AVMs or used as part of a multimodality treatment regimen consisting of partial embolization, partial excision and consecutive radiation of the residual nidus in initially very large AVMs. Embolization therapy-such as radiosurgery-carries a significant risk of morbidity (8%) and a mortality rate of up to 6%. It should only be considered for AVMs that are expected to be fully obliterated afterwards, or for primary inoperable AVMs that are to be changed into operable ones by embolization. Size reduction of otherwise operable AVMs does not justify the additional risk of embolization. Close collaboration of the specialties involved is desirable.

Adolescent↗
PubMed1996

Primary central nervous system non-Hodgkin's lymphoma (PCNSL): does age and histology at presentation affect outcome?

Primary Non-Hodgkin's lymphoma of the central nervous system (PCNSL) was diagnosed by computer-assisted stereotactic biopsy in 27 non-AIDS patients (22 men, 5 women; mean age, 50.6 years, median age 53 years). Among the various histologies, fourteen patients had diffuse large cell lymphoma (DLC), five had diffuse, small, non-cleaved lymphoma (DSNC) and five had diffuse mixed cell lymphoma (DMC). Immunohistochemical analysis revealed 6 B-cell and 3 T-cell types. Multiple lesions occurred in 11 patients. Most patients received radiation therapy and some received adjunctive and/or salvage chemotherapy. Several factors correlated with survival, median survival for the entire group was 356 days (0.975 years). However, Median survival was 1982 days (5.43 years) for the 8 patients who were less than 45 years old at diagnosis versus 283 days (0.77 years) for the 18 patients who were older (p = 0.03). One patient was lost for follow up. Four of the 5 patients who have survived for more than four years were less than 45 years of age; of these 2 had T-cell lymphoma. Only 3 of the 11 patients with multiple lesions died within the first year. A proportional hazards model was derived for the group and suggested that older age and uncleaved histology are associated with shorter survival. Treatment protocols should include stratification factors to allow comparison between groups with different characteristics and to account for age and/or histology dependent on differences in response.

Adolescent↗
PubMed1995

Amount of subarachnoid blood and vasospasm: current aspects. A transcranial Doppler study.

Subsequent to admission after aneurysmal subarachnoid haemorrhage (SAH), 120 patients (74 women and 46 men) underwent microsurgical clipping of a total of 158 cerebral aneurysms within 96 hours after the bleed. Their mean age was 46 (20-91) years. Computed tomography (CT) findings were graded according to the modified Fisher scale and all patients had daily transcranial doppler (TCD) recordings of their basal cerebral arteries. In 19% of SAH was grade I on CT, in 44% grade II and in 37% grade III. The rate of patients who developed severe vasospasm as documented by TCD (mean blood flow velocities exceeding 160 cm/s on 2 or more consecutive days) was 39% for grade I patients, 26% for grade II patients and 34% for patients with SAH grade III on the initial CT. There was no difference in the rate of occurrence of severe vasospasm, when the patients were split into 2 groups according to the time of performance of the initial CT scan-within 24 hours, and 48-80 hours after SAH, respectively. It is concluded that the amount of subarachnoid blood on the initial CT scan should no longer be used as the indicator for occurrence and severity of the multifactorial entity vasospasm.

Adult↗
PubMed1995

Intraventricular recombinant tissue plasminogen activator for lysis of intraventricular haemorrhage.

A prospective series of 20 patients with moderate to severe intraventricular haemorrhage (IVH) was studied for the effect of intraventricular administration of recombinant tissue plasminogen activator (rt-PA) on reduction of haematoma volume and prognosis. On the day of haemorrhage ventriculostomy was performed and 2 to 5 mg of rt-PA were injected via the external ventricular drainage, followed by drainage closure for two hours. In 14 patients rt-PA treatment was repeated. Computed tomography showed complete clot lysis or substantial reduction of intraventricular haematoma volume in 19 patients within 96 hours; the clearance of the third and fourth ventricle preceded the clearance of the lateral ventricles. Decrease of ventricular enlargement was seen in all but one patient with initial ventricular dilatation. Increase of haematoma volume and ventricular size was found in one patient. Outcome was minor or no neurological deficit in nine patients, disabling neurological deficit in six patients, and vegetative status in four patients. One patient did not survive the IVH. Intraventricular treatment with rt-PA seems effective in rapid lysis of intraventricular haematoma and normalisation of impaired CSF circulation. This treatment may contribute to an improvement in prognosis of moderate to severe IVH.

Adult↗
PubMed1995

Stereotactic puncture and lysis of spontaneous intracerebral hemorrhage using recombinant tissue-plasminogen activator.

We have tested a treatment protocol for intracerebral hemorrhage (ICH), consisting of stereotactic insertion of a catheter into the clot, hematoma lysis by the injection of a fibrinolytic agent, recombinant tissue-plasminogen activator (rt-PA), and closed system drainage of the liquefied clot. Fourteen patients underwent computed tomographically guided stereotactic hematoma puncture and silicone tube insertion within 72 hours of intracerebral hemorrhage. The majority (nine patients) suffered from ganglionic ICH, and the size of the hematoma ranged between 3 x 3 x 4 cm and 7 x 7 x 4 cm (mean, 5.2 x 4 x 3.6 cm). All patients had major neurological deficits with or without an impaired level of consciousness, but without signs of transtentorial herniation. The initial, then daily, dose (in milligrams) of rt-PA administered via the silicone tube equalled the maximal diameter (in centimeters) of the original and remaining clot as measured initially, then daily, by computed tomographic scan. The number of rt-PA injections was four in one patient, three in eight patients, two in four patients, and one in one patient, and the total dose of rt-PA required ranged from 5 to 16 mg (mean, 9.9 mg). After rt-PA injection, the tubing was clamped for 2 hours and then opened to drain spontaneously through a closed system against 0 cm of pressure. At follow-up 6.6 months (mean) after treatment (ranging from 3 to 13 months) and according to the Glasgow outcome score, one patient was Grade V, four were Grade IV, five were Grade III, two were Grade II, and two had died.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

[Local thrombolytic treatment of spontaneous intracerebral hemorrhage with plasminogen activator (rt-PA). Indications and limits].

Twenty patients underwent a regimen of stereotactic puncture and consecutive local lysis with recombinant tissue plasminogen activator (rt-PA) for their spontaneous intracerebral hemorrhage (ICH). Rt-PA was administered via a stereotactically placed silicone catheter according to a hematoma-size-related formula. There was no extensive intraoperative hematoma aspiration so that the capacity of rt-PA for blood-clot lysis could be investigated. Fifteen patients were somnolent/stuporous on admission and 5 comatose, the hematoma-size ranging from 3 x 3 x 4 cm up to 7 x 4 x 4 cm (mean: 5.1 x 3.9 x 3.5 cm). Control computed tomography (CT) was performed on a daily basis, and in 19 patients the hematoma showed complete or almost complete resolution on CT within 4 days. The rt-PA dosage necessary ranged from 5 to 14 (mean: 8.5) mg. Rt-PA application was performed once in 1 patients, twice in 7, three times in 11 and four times in 1 patient. On follow-up after a mean of 7.2 months 3 patients had died (Glasgow Outcome Score--GOS I). Another was GOS II, 10 GOS III, 5 GOS IV and 1 had made an excellent recovery (GOS V). Patients who were somnolent or stuporous on admission or who exhibited secondary deterioration of their level of consciousness benefitted from the treatment protocol. Early postoperative mobilization and thereby reduction of secondary complications during the patient's stay in the intensive care unit appear to be possible. Comatose patients did not benefit from this treatment and those should be treated conservatively.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

The extreme lateral transcondylar approach to aneurysms of the vertebrobasilar junction, the vertebral artery, and the posterior inferior cerebellar artery.

The unilateral suboccipital craniotomy is the commonly performed approach to aneurysms of the vertebrobasilar junction, the vertebral artery, and the posterior inferior cerebellar artery (PICA). Many of these aneurysms are placed anterior or anterolateral to the brain stem, necessitating brain stem retraction for adequate exposure. Small dorsolateral enlargement of the foramen magnum, partial resection of the occipital condyle, and removal of the jugular tubercle allow access to the neurovascular structures ventral to the medulla without retraction of the neuroaxis. This extreme lateral transcondylar approach was performed in 20 patients with aneurysms of the vertebrobasilar junction, the vertebral artery, and the PICA; intraoperatively, two suspected aneurysms proved to be vascular malformations. Occlusion of the aneurysm and vascular malformation was successfully performed in 16 patients, resection of the vascular malformation was achieved in 1 patient, and the vertebral artery was clipped in 3 patients with fusiform aneurysms without complications related to the extreme lateral transcondylar approach. Unobstructed exposure of the aneurysm, parent artery, and neural structures without retraction of the sensitive lower brain stem are the major advantages of the extreme lateral transcondylar approach.

Journal Article↗
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↗
PubMed1992

HOM/HOX homeobox genes are present in hydra (Chlorohydra viridissima) and are differentially expressed during regeneration.

Hydra, a diblastic animal consisting of two cell layers, ectoderm and endoderm, is one of the most ancient animals displaying an anteroposterior axis with a head and a foot developing from an uncommitted gastric region. As such, hydra is an interesting model for studying the presence and function of homeobox genes in a phylogenetically old organism. By screening a Chlorohydra viridissima cDNA library with a 'guessmer' oligonucleotide, we have cloned several such cnidarian homeobox-containing genes (cnox genes). Two of these, cnox1 and cnox2, display labial and Deformed type homeodomains respectively and could represent two ancestral genes of the HOM/HOX complexes; cnox3 exhibits some similarity to the BarH1 and the distal-less type homeodomains and a fourth gene is highly related to the msh/Hox7 type of homeodomain. We used quantitative PCR to study levels of expression of these genes along the body axis and during head regeneration. In all cases, the expression in heads was stronger than that in the gastric region. cnox1 transcripts dramatically peaked within the first hours of head regeneration, whereas cnox2 and cnox3 reached their maximal levels 1 and 2 days after cutting respectively. This differential expression of homeobox genes at various stages of regeneration suggests that they play specific roles in regenerative processes.

Amino Acid Sequence↗
PubMed1985

[Intravenous DSA following kidney transplantation].

Intravenous DSA is a simple angiographic technique in the follow-up of patients with renal transplants. It is of value in the post-operative anuric phase, for investigating renal function which is deteriorating and for demonstrating, or excluding, stenosis of the renal artery at the anastomosis during the development of hypertension. Changes in the peripheral arteries are not usually demonstrable. Reduced opacification of the parenchyma is observed during rejection and if there has been damage to the transplant, but is not seen if the transplant is functioning normally.

Adult↗