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Biomedical subjects

A Ferbert

Publications and source records attributed to A Ferbert.

89 records · Page 5Linked to original sources
PubMed1987

The subcortical generated somatosensory evoked potentials in non-cephalic, cephalic, and anterior neck referenced recordings in a patient with a cervico-medullary lesion: a clue to the identification of the P14/N14 and N13 generators.

Median nerve somatosensory evoked potentials (SEPs) were studied in a patient before and after the development of a cervico-medullary lesion. The first examination demonstrated normal subcortical generated potentials N13 and N14. The second examination, following a subarachnoid haemorrhage at the cervico-medullary junction, displayed a delayed and reduced amplitude P14/N14 peak on both sides. P14/N14 showed the same latency in all montages, using non-cephalic, cephalic and anterior neck references. The N13 component was not significantly changed in latency compared with the first examination. The latencies of the N13 peak were variable in the different montages. They increased from the lower (C7) to the upper (C2) neck, whereas the latency of the N13 onset was identical in all montages. This alteration might be caused by a delayed near-field activity at C2 overlapping the N13 component. These results fit the hypothesis of two major generators responsible for subcortical SEPs; a near-field N13 component at the level of the lower neck and a far-field P14 component arising from the level of the cervico-medullary junction. An additional minor near-field activity generated by the cuneate nucleus is suspected.

Adult↗
PubMed1987

Carotid endarterectomy: factors influencing perioperative complications.

Early carotid surgery has been suggested to be an important cause of perioperative deterioration due to secondary haemorrhage into a recent brain infarction. It has also been suggested that the existence of preoperative neurological deficits may worsen the prognosis of surgical treatment in carotid disease. Neither of these observations could be confirmed; severe perioperative complications (5%) in this study of carotid endarterectomy were strongly related to the degree of carotid stenosis. This aspect of carotid surgery has not been previously studied. Even though technical difficulties may play an exaggerated role in a training hospital system, it is nevertheless necessary to assess the impact of surgical procedures of different extent when the "acceptable risk" for carotid surgery is calculated.

Adult↗
PubMed1987

"Distal stump" of the internal carotid artery with ascending pharyngeal artery collateralisation. A potential source for further embolic ischemia.

In 2 patients, clinically exhibiting recent amaurosis fugax and small cortical infarction, carotid occlusion had been shown by means of doppler ultrasound. IA-DSA showed a collateral circulation within the distal carotid artery in the base of the skull via the ascending pharyngeal artery. The slowly perfused stump of a distal carotid artery is supposed to be a potential source of emboli into the retinal or intracranial territories.

Carotid Artery Diseases↗
PubMed1986

Isolated brain-stem death. Case report with demonstration of preserved visual evoked potentials (VEPs).

Brain-stem death is a state in which brain-stem functions have ceased whereas the hemispheres still have electrical activity. We report a patient with a haematoma over the cerebellum and the pons who showed a preserved electroencephalogram and VEPs whereas all clinical signs of cerebral death was present. Normal VEPs in isolated brain-stem death have not yet been reported. We conclude that in any case of infratentorial lesion, an electroencephalogram should be recorded for the diagnosis of brain death.

Brain Death↗
PubMed1986

Acute vertebral-basilar thrombosis. Angiologic-clinical comparison and therapeutic implications.

The clinical-angiologic data and the clinical outcome in 66 patients with acute vertebro-basilar thrombosis treated with antiplatelet agents, anticoagulants, or fibrinolytic agents are presented. Forty-three patients were treated with local intraarterial infusion of streptokinase or urokinase proximal to the thrombotic occlusion; 14 patients in this group (33%) survived, only one of whom was in deep coma when therapy was started. Twenty-three patients did not receive fibrinolytic therapy; 4 of these patients (17%) who exhibited mild brainstem-related symptoms survived. This study implies that early diagnosis and treatment in vertebrobasilar stroke in progression may achieve improved survival.

Acute Disease↗
PubMed1986

[Electrophysiologic findings in lacunar infarcts].

Lacunar lesions are small infarctions in the territory of small penetrating arteries of the brain. Because of their small size these lesions can only in part be detected by CT. Clinical symptoms do not always correspond with the lesions visible in the CT. We studied the somatosensory evoked potentials (SEP), the visual evoked potentials (VEP) and the electrically elicited blink reflex in 50 patients with lacunes to determine if there are any other lesions which are not detectable by clinical examination or CT alone. While VEP and the blink reflex showed pathological results in only a few of these patients the SEP were pathological in about 75%. The multiplicity of the lesions may be documented by means of these investigations.

Aged↗
PubMed1986

[Validity of early acoustically-evoked potentials in the diagnosis of brain death].

Brainstem acoustic evoked potentials (BAEP) in clinically proven brain death are already described in the literature. In most cases there were no reproducable BAEP or only wave I ipsilateral. In a few cases, shortly after the onset of brain death, wave I and a wave II ipsilateral have been detected. 40 Patients were examined during developing brain death and in brain death. Using an ipsilateral and contralateral montage (mastoid/vertex) four different patterns of BAEP in brain death could be distinguished: Wave I ipsilateral and wave II ipsilateral, reduced in amplitude and delayed in latency and a wave I-contralateral, Wave I ipsilateral and wave I-contralateral, Only wave I ipsilateral, No reproducable BAEP. In clinically not brain dead patients, three different patterns of BAEP are recorded which should be known in order to comment on the validity of the method in the diagnosis of brain death: Only wave I and a flat and late wave, only recordable using several reproductions and with a low rate of artefacts. Only wave I recordable while the patient is still breathing spontaneously (false positive results). Reversible loss of wave I. Ignoring the results, the BAEP may lead to false positive results in the diagnosis of brain death.

Brain Death↗
PubMed1985

Remarks on the follow-up of cerebellar astrocytomas.

A retrograde study was performed in 105 patients operated upon between 1950 and 1972 for a cerebellar astrocytoma. Complete histories were available for 89 patients. Forty-five patients died within the first 3 months after operation. Of the 32 patients who were still alive, 14 patients had been operated upon 20-30 years previously and 18 patients 10-19 years previously. Twelve patients died over 3 months after the operation; in 6 cases, recurrence of tumour was the cause of death. Of the 7 patients who were irradiated post-operatively, 5 died. In 26 patients the tumor had infiltrated the brain-stem and only 7 patients survived the operation. However, 2 patients are still alive after 25 and 10 years, respectively. The findings indicate that patients operated upon for a localized cerebellar astrocytoms can be considered cured and irradiation and chemotherapy are not warranted. When the tumour has infiltrated the brain-stem, a survival period of more than 20 years is possible after partial resection.

Adolescent↗
PubMed1985

A case of spinal paraganglioma.

The neuroradiologic finding of a paraganglioma in the vertebral canal is described here for the first time. These tumors occur more frequently than was previously presumed. Similarities with paragangliomas in the craniocervical region are apparent on angiograms. We consider angiography to be indicated when, in association with a spinal tumor, urinary biogenic amine levels are elevated. When necessary, embolization can be performed after angiography.

Angiography↗
PubMed1985

[Monitoring of therapeutic neuroradiologic examination and therapeutic procedures using evoked potentials].

Interventional neuroradiology makes use of different diagnostic and therapeutic catheterization techniques. Treatments performed are local intraarterial thrombolytic therapy, embolization and occlusion of brain supplying arteries, percutaneous transluminal angioplasty and intraarterial application of drugs. These treatments make it most important to check the patients neurological state during the procedure. Intraoperative monitoring of evoked potentials offers the opportunity to get objective information about changes in certain central nervous system functions even in anaesthesized patients. Usually intraoperative monitoring is performed to obtain information whether the function of structures at risk remains stable or is altered by the operation. This represents a more passive, observing way of monitoring. During interventional neuroradiology one is enabled to take additionally a more active and experimental way of monitoring by using the advantages of special catheter techniques like series of reversible balloon occlusion or intraarterial drug application. This leads to a dialogue between the radiologist and the neurophysiologist about the safety or the risk of the next step during a procedure. There are mainly two types of new information that can be achieved by active monitoring: the identification of functional territories of single or multiple feeding vessels and new insights into hemodynamics and the establishing of new sufficient collaterals. We have used intraoperative neuromonitoring in 35 patients during interventional neuroradiology. Our findings will be summarized and the usefulness of the different monitoring methods will be discussed.

Amobarbital↗
PubMed1984

Local intraarterial fibrinolytic therapy in inaccessible internal carotid occlusion.

Two exemplary cases of upper carotid occlusion and successful local intraarterial fibrinolytic therapy are described. To achieve a positive result one has to perform a balloon occlusion of the affected internal carotid artery while applying the fibrinolytic agent. Possible time limits of instigating therapy are discussed especially if the lenticulostriatal arteries are additionally affected.

Adult↗
PubMedDate not supplied

Non-invasive determination of the distribution of the conduction velocity of the large-diameter fibers in peripheral nerves. Estimate based upon a single recording of the stimulus response of the nerve.

The paper describes a method for the estimation of the frequency of occurrence of fibers with a given conduction velocity among the stronger myelinated fibers of superficial nerves. The method is primarily suited for the examination of sensory nerves. To mixed nerves it can be applied only if interference by excited myopotentials is sufficiently weak. A single averaged recording of the compound action potential of the nerve evoked by a supra-maximal electrical stimulus serves as input. It is shown that integration of that curve with respect to time yields an amplitude weighted graph of the density of fibers with given travel times between the stimulus site and the recording electrode. Unweighting that curve yields the distribution characteristic of the travel delays which can easily be converted to a graph of the conduction velocity density of the fibers in the excited ensemble.

Action Potentials↗
PubMedDate not supplied

Hemispheric asymmetries of early cortical somatosensory evoked potentials revealed by topographic analysis.

Scalp topography of the early cortical SEPs was analysed in 50 normal right handed subjects. The following hemispheric asymmetries of the potentials were found: 1) The maximal amplitude of N20 was located predominantly at the P electrode after right sided stimulation, but varied between the CP, P and O electrode after left sided stimulation. 2) The N20 amplitudes were higher after right sided stimulation in approximately 70% of the subjects and the P25 and N30 amplitudes were higher after left sided stimulation in again approximately 70% of the subjects. No side difference of amplitudes was found for the subcortical N14. The N20 amplitude and location asymmetries were attributed to an anatomical asymmetry of the somatosensory cortex.

Adult↗