Biomedical subjects

H Bertalanffy

Publications and source records attributed to H Bertalanffy.

89 records · Page 5Linked to original sources

PubMed1994

Ultrasound-guided craniotomy for minimally invasive exposure of cerebral convexity lesions.

The authors describe a method of real-time ultrasound-guided craniotomy for an approach to cerebral convexity lesions. During surgery, a specially designed high frequency (7.5 MHz) sector probe with a thin (11 mm), extended tip is used to image the cerebral lesion through a single burr-hole. The distance between burr-hole and lesion and the direction of the target are then determined from the ultrasound images, and craniotomy is completed with the aid of these parameters. Errors in the preoperative planning of the approach, which might result in incorrect placement of the craniotomy, can easily be recognized and corrected at an early stage of the operation, before the craniotomy has been completed. This technique greatly improves the accuracy in placing craniotomy flaps. Since the risk of misplacing the craniotomy is virtually eliminated in lesions which are identifiable on ultrasound images, the technique allows the surgeon to keep the skull opening as limited as possible.

Brain Neoplasms↗

PubMed1994

Lysis of basal ganglia haematoma with recombinant tissue plasminogen activator (rtPA) after stereotactic aspiration: initial results.

In a series of 10 patients with stereotactically treated basal ganglia haematoma rtPA was used to dissolve remaining clots. Pre-operative haematoma volume ranged between 39 and 111 cm3 (average 56 cm3). Stereotactic aspiration alone yielded an average volume reduction of 60% (range 23 to 78%). Haematoma cavity was instillated with rtPA repeatedly beginning 24 hours after the stereotactic intervention. At the end of rtPA therapy between 2 and 4 days after onset of the haemorrhage 67 to 92% (average 84%) of the initial haematoma was removed in all patients. More than 80% of the pre-operative clot could be removed in 8 out of 10 patients between day 2 and 4. There were no signs of rtPA related toxicity. At the end of the follow-up period (between 4 and 17 months--mean 8 months) 6 patients were awake, oriented and with a residual hemiparesis able to live in their familiar environment. It is concluded that local rtPA instillation is an effective additional treatment to further resolution of deep seated intracerebral haematomas after stereotactic aspiration.

Adult↗

PubMed1994

A new model for in vivo observation of the feline spinal microcirculation: the closed spinal window.

A new experimental model is described that uniquely allows the in vivo observation and quantification of vascular caliber changes on the dorsal surface of the feline spinal cord. The model consists of a rectangular Plexiglas window that is sutured to the lumbar dura and is supported by a special holder. Inlet and outlet tubes attached to the window serve for topical applications of mock cerebrospinal fluid or vasoactive agents to the surface of the cord and for continuous monitoring of intrathecal pressure. Pial vessels below the window were observed at 200-fold magnification with the aid of a microvideo camera. Spinal arterioles reacted to hypercarbia and superfusion with acetylcholine solution in a manner similar to cerebral arterioles. Tests with increased intrathecal pressure showed that the window remained watertight between 25 and 130 mm Hg, with an average leakage pressure of 57.8 +/- 33.5 mm Hg. To promote the use of this model in other laboratories, the authors give a detailed description of the closed spinal window preparation and report their experiences gained from 50 experiments. It is concluded that the closed spinal window is a highly reproducible model, suitable for the study of the feline spinal microcirculation for several hours in vivo.

Animals↗

PubMed1993

Effect of recombinant tissue plasminogen activator on clot lysis and ventricular dilatation in the treatment of severe intraventricular haemorrhage.

Twelve patients with severe intraventricular haemorrhage (IVH) underwent intraventricular thrombolysis with recombinant tissue plasminogen activator (rtPA). External ventricular drainage was performed in all patients within 24 hours of haemorrhage. Fibrinolytic therapy was started within 24 hours from the onset of symptoms in ten cases, and in two further cases after 48 hours and 5 days, respectively. Two to 5 mg of rtPA were injected via the ventricular catheter into one or both lateral ventricles. The injection was repeated at intervals ranging from 6 to 24 hours until CT scans demonstrated a substantial reduction of intraventricular blood. The total rtPA doses per patient ranged from 3 to 31 mg. CT scans showed a marked reduction of intraventricular blood and normalization of ventricular size within 24 to 48 hours from the beginning of the fibrinolytic therapy. Rapid reduction of elevated intracranial pressure by continuous diversion of cerebrospinal fluid could be achieved in all patients, because the ventricular catheters never became obstructed by clotted blood during the fibrinolytic therapy. During the period of treatment, the level of consciousness, as classified according to the Glasgow Coma Scale, improved from a mean value of 7 to 12. One fatal case of meningitis most probably due to the ventriculostomy was the only complication related to the treatment. This method of treatment might improve the prognosis in patients in whom a large intraventricular haematoma volume, ventricular dilatation, and impaired cerebrospinal fluid circulation are major determinants for the outcome.

Aged↗

PubMed1993

In vivo effect of visible light on feline cortical microcirculation.

The present study was designed to test the hypothesis that prolonged illumination of the cerebral cortex, for instance during neurosurgical interventions, may affect the pial microcirculation. Experiments were performed with the closed window technique in cats. The cortical surface below the window was exposed to visible, cold light of 61,000 lumens/m2 (lux) over a period of 1 to 5 hours. Pial arterioles reacted with a slight initial dilatation to 106.8 +/- 2.6% of their resting diameter after switching to the high intensity light. Measurements of the cortical surface temperature showed an average temperature increase of 1.5 +/- 0.34 degrees C within the first 10 minutes of illumination. For assessment of pial vascular function, the responses to topical application of acetylcholine (ACh) were tested before and during the illumination period. The effect of sustained illumination on the cortical microcirculation consisted of abolition of the endothelium dependent relaxation due to ACh, and of intravascular thrombus formation, the latter, however, only in the presence of topically applied ACh. The suspected mechanism responsible for these functional alterations is light-induced generation of free oxygen radicals which are known to inactivate or destroy the endothelium-derived relaxing factor (EDRF). Further studies are recommended to elucidate the practical and clinical relevance of these findings to neurosurgical procedures.

Acetylcholine↗

PubMed1993

Ventral brain stem schwannoma at the entry zone of the hypoglossal nerve.

The unusual case of a ventral brain stem schwannoma located at the entry zone of the hypoglossal nerve in a 49-year-old woman is reported. The diagnosis of a schwannoma was confirmed histologically after partial tumor resection via the dorsolateral, suboccipital, transcondylar approach. Hypotheses for the pathogenesis of intramedullary schwannomas are discussed.

Brain Stem↗

PubMed1993

Regional exposure of cerebral convexity lesions.

The utility and reliability of a simple technique for the localization of cerebral convexity lesions are retrospectively analyzed in 83 intracranial procedures. The technique is based on data obtained from preoperative computed tomography (CT) scans, and on a few anthropological landmarks which usually can be identified on both the patient's head and skull radiograms. This method allowed precise placement of small craniotomy flaps (3 to 7 cm in diameter) in 94% of the patients studied. In the remaining, localization errors were corrected either by enlarging the craniotomy opening (3 cases), or by rescanning during the operative procedure (2 cases). Due to its technical simplicity and reliability in the vast majority of cases, the bony landmark method constitutes a recommendable alternative for the localization of convexity lesions, being particularly useful when highly sophisticated equipment is not available.

Adult↗

PubMed1992

Management of cerebellar infarction with associated occlusive hydrocephalus.

We review here 10 cases of cerebellar infarction and associated occlusive hydrocephalus. Surgical therapy consisted of placement of a permanent shunt in 4, and a temporary external ventricular drainage in 6 individuals. This treatment regimen was effective in 9 cases and remained without adequate response in only 1 patient with multiple supra- and infratentorial infarctions. These results and similar reports from the literature suggest that treatment of the hydrocephalus alone might be sufficient in most cases and should therefore constitute the primary treatment of choice in patients presenting with cerebellar infarction and obstruction of cerebrospinal fluid (CSF) pathways.

Adult↗

PubMed1992

Indications for surgery and prognosis in patients with cerebral cavernous angiomas.

Seventy-three cerebral cavernous angiomas were removed microsurgically from a series of 71 patients between August, 1983 and December, 1989. This retrospective investigation assessed the current indications for surgery and determined the prognosis for patients with cerebral cavernous angioma. There were 38 males and 33 females with a mean age of 37 years. Analysis included clinical presentation and history, neuroradiological findings, indications for surgery, and postoperative course. After an average follow-up period of 15 months, 35 patients were symptom-free, 16 had improved preoperative complaints, six were unchanged, and eight had deteriorated. Microsurgical extirpation of the malformation is indicated in all symptomatic patients where neuroimaging demonstrates the presence of a readily accessible cerebral cavernoma. Surgery is recommended in cases with deep-seated lesions causing massive hemorrhage, repetitive minor bleeding, or significant long-standing and progressive neurological disabilities. Clinically silent cavernomas located in eloquent regions of the brain contraindicate surgery, but should be closely monitored. Patients presenting with convulsions or neurological deficits caused by easily accessible cavernomas of the hemispheres have the best prognosis and a negligible risk for surgical complications. Those with deep-seated lesions of eloquent regions of the brain that have bled or caused sustained neurological disorders face the highest risk for morbidity owing to the surgical intervention, requiring careful preoperative evaluation.

Adolescent↗

PubMed1992

Usefulness of hemilaminectomy for microsurgical management of intraspinal lesions.

Hemilaminectomy is a limited, unilateral approach to the spinal cord that provides excellent exposure of the dorsolateral and ventral portions of the spinal canal. This approach is most suitable for microsurgical management of the majority of extramedullary tumors. Contrary to conventional laminectomy, the posterior supporting structures of the spine are completely preserved on the contralateral side with this access route. The procedure has been applied in 3 patients who harbored a cervical neurilemmoma, a cervical lipoma, and a thoracic neurilemmoma, respectively. Optimal exposure of the lesion was achieved in each case, and each patient's symptoms improved or completely resolved postoperatively. There were no surgical complications. It is concluded that hemilaminectomy combined with microsurgical techniques should be given priority over standard laminectomy in the surgical management of extramedullary lesions arising in the spinal canal.

Female↗

PubMed1992

Limits of the transoral approach in craniospinal malformations.

Over a 15-year period, 15 patients with craniospinal malformations were operated on using the transoral route. Ten patients had basilar impression and five had atlantoaxial dislocation; nine patients had associated lesions. Patients treated with reposition and dorsal fusion recovered well without ventral decompression. We found that transoral odontoidectomy is suitable as a primary decompressing measure only in ventral compression or nondislocated atlantoaxial conditions.

Journal Article↗

PubMed1991

Microsurgery of deep-seated cavernous angiomas: report of 26 cases.

The authors review 26 patients with deep-seated cavernous angiomas which were removed by microsurgery. Ten of the angiomas were located in the insula and basal ganglia, 2 in the thalamus, 5 in the midbrain, 8 in the pons, and 1 in the brachium pontis. The patients were among 73 consecutive cases operated on between August 1983 and December 1989 for symptomatic cavernous angiomas in various locations. In 11 cases total excision of the cavernoma was achieved without producing additional neurological deficits. Postoperative neurological recovery was delayed in 7 patients. In the remaining 8, the complicated postoperative course was caused by bleeding from residual parts of the malformation or damage to long-tract pathways in two cases, respectively, vascular injury during dissection in three cases, and paradoxical air embolism in one case. In order to achieve a satisfactory surgical result, it is stressed that particular attention has to be paid to the operative approach, to careful dissection and complete removal of the malformation, to perforating arteries, and to anomalous venous drainage.

Adolescent↗

PubMed1991

The dorsolateral, suboccipital, transcondylar approach to the lower clivus and anterior portion of the craniocervical junction.

The authors review their experience with a dorsolateral approach to the anterior rim of the foramen magnum and adjacent region. The operative technique includes exposure of the vertebral artery at C1, partial resection of the occipital condyle and lateral atlantal mass, and extradural drilling of the jugular tubercle. This approach has been applied in six patients who harbored intradural space-occupying lesions located ventral to the lower brain stem. Excision of the neoplasm was virtually total in all but one patient, in whom biopsy was the primary goal of the intervention. No morbidity and no mortality were associated with this approach. The main advantage of the dorsolateral, suboccipital, transcondylar route is the direct view it offers to the anterior rim of the foramen magnum without requiring brain stem retraction.

Adult↗

PubMed1990

Large colloid cyst in lateral ventricle simulating brain tumour. Case report.

This case report describes a patient presenting with symptoms of increased intracranial pressure, whose computerized tomographic (CT) scan was highly suggestive of a large low-grade glioma invading the basal ganglia. Magnetic resonance imaging (MRI) revealed a well-demarcated space-occupying mass of increased intensity in the left lateral ventricle and adjacent white matter. Following stereotactic biopsy, which yielded a homogeneous jelly-like material, the mass was removed microsurgically and was found to be most like a colloid cyst on histological examination. Discussion focuses on the clinical and differential diagnostic implications of this very unusual combination of findings.

Adult↗

PubMed1989

Complications of anterior cervical discectomy without fusion in 450 consecutive patients.

The complications of anterior discectomy without fusion were analyzed on the basis of 450 consecutive cases treated surgically for degenerative disc disease. There was no death related to the procedure. The most common complication was a worsening of the pre-existing myelopathy. This occurred in 3.3%, including one case with severe medullary contusion. Wound infection developed in 1.6%. Additional radicular symptoms and wound haematoma, respectively, occurred in 1.3%; recurrent nerve palsy, Horner's syndrome, and respiratory insufficiency, respectively, in 1.1% of the cases. Epidural haematoma and instability of the cervical spine, respectively, occurred in 0.9%, nerve root lesion and aseptic spondylodiscitis, respectively, in 0.4%. There was one case each (0.2%) with a pharyngeal lesion, meningitis due to dural perforation, transient additional myelopathy, and epidural abscess. The results and the management of complications are discussed in relation to numerous previously published reports, including posterior procedures and anterior fusion techniques. Precise knowledge of all potential accidents and pitfalls related to the surgical procedure and of their aetiology may contribute to preventing failures. The rate of complications in this series has been reduced in the past years by better patient selection, by paying more attention to correct positioning of the patient during the operation, and by meticulous removal of all offending structures. Discectomy without interbody fusion is now considered to be a reasonably safe procedure with an acceptable operative morbidity and lack of mortality.

Adult↗

PubMed1988

Clinical long-term results of anterior discectomy without fusion for treatment of cervical radiculopathy and myelopathy. A follow-up of 164 cases.

Between 1976 and 1983, 251 patients underwent surgery for the treatment of cervical degenerative disc disease. Anterior microsurgical discectomy at one or more cervical segments without interbody fusion was performed in each case. 109 patients with radiculopathy and 55 patients with myelopathy were followed up clinically 1 to 8 years postoperatively. A soft disc lesion was found in 72, a hard disc lesion in 92 patients. Of all radicular symptoms and signs, brachialgia and motor deficits of the upper extremities showed the highest improvement rates. The medullary complaints were improved in 80%, the progression of the disease was arrested in 93% of myelopathic cases. An excellent or good long-term result was achieved in 82% of patients with radiculopathy and 55% of those with myelopathy. The outcome was best in cases with soft disc lesions, with monosegmental disease, in individuals under 50 years of age, and in patients with a sudden onset and a short duration of symptoms. These results are comparable with those obtained by other surgical methods.

Adult↗

PubMedDate not supplied

Argon plasma coagulation (APC) in brain tumor surgery: experimental study and clinical experiences.

OBJECTIVE: The present study aims to provide preliminary results of the thermal effects on rat brain tissue after argon plasma coagulation (APC). It also presents and discusses the clinical experiences in the treatment of brain tumor using APC. MATERIALS AND METHODS: A controlled study of APC in the rat brain was conducted. Twelve rats were randomly divided into 2 experimental groups. In the first group (n = 6), histopathological evaluation was performed 2 days following the coagulation. In the second group (n = 6), the evaluation was performed 12 days post operation. In a prospective study of APC-treated tumor tissue in 3 patients, the depth of plasma penetration and histological alteration were evaluated. RESULTS: In the animal experiment, extent of tissue defect became significantly smaller after 12 days (p = 0.010). The maximum depth of tissue alteration after APC application was limited to 2.15 mm (range: 1.5-2.15 mm) at day 2. The histological alteration of tissue after the thermal injury can be divided into 3 zones. In addition, the depth of tissue alteration in the APC-treated human brain tumor was measured in vertical and horizontal planes under light microscope. Similar to the animal experiment result, penetration of the plasma energy in human brain tumors was limited to a maximum of 2.13 mm (range: 1.6-2.13 mm). CONCLUSION: The limited depth of energy penetration may confirm APC as a safe and beneficial tool for coagulation of human brain tissue. However, further clinical studies are required to evaluate the suitability and indications of this method in brain tumor treatment.

Animals↗