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Biomedical subjects

H Buchner

Publications and source records attributed to H Buchner.

At least 73 records · Page 4Linked to original sources
PubMed1990

Brainstem auditory evoked potentials and somatosensory evoked potentials in pontine haemorrhage. Correlations with clinical and CT findings.

Electrophysiological studies were performed on 17 patients with pontine haemorrhage. Most had had massive hypertensive bleeding, leading to death in 12 of them within 3 months. Of the 5 surviving patients, 2 had a poor outcome and 3 a moderately good outcome. Brainstem auditory evoked potentials (BAEPs) and somatosensory evoked potentials (SEPs) were recorded in all patients, mostly with serial recordings. BAEPs were pathological in all patients. The most important finding was a reduction in amplitude or loss of waves. With a loss of waves after wave II bilaterally all patients died; the 2 patients with a normal amplitude of waves I-V at least on one side, survived in good condition. Further prognostic conclusions were not possible. The correlation with the clinical state was limited and was best for small unilateral tegmental haemorrhages. Eleven of the 17 patients suffered bilateral loss of the N20 component of the median nerve SEP. All these patients died. In patients with unilateral loss of the SEP the outcome could be favourable even if the bleeding extended across the midline. 'Subcortical' SEPs were not significantly altered. EEG findings in 15 and visual evoked potentials in 4 patients showed preserved forebrain electrical activity even in patients in poor condition.

Adult↗
PubMed1990

Loss of brainstem acoustic evoked potentials with spontaneous breathing in a patient with supratentorial lesion.

The loss of brainstem acoustic evoked potentials (BAEP) is considered as a confirmatory test for the diagnosis of brain death in patients with supratentorial lesions. We report a patient with ischemia in the territory of the left middle and anterior cerebral artery, who showed a loss of BAEP waves III-V as a sign of brainstem compression, but maintained spontaneous breathing and EEG activities. We conclude that occasionally BAEP may provide misleading results in the diagnosis of brain death.

Aged↗
PubMed1990

Reliability of electroencephalogram in the diagnosis of brain death.

The definition of brain death includes the irreversible loss of all brainstem and forebrain functions. The electroencephalogram (EEG), used to test forebrain functions, is part of the diagnostic armamentarium and is considered necessary even after primary infratentorial lesions. A review of both the current literature as well as new data on an interrater agreement and intrarater stability study provide the basis for a discussion on the reliability of EEG recording in this context and on the definition of brain death. Under normal conditions, the presence of an electrocerebrally inactive EEG is a valid indicator of brain death. However, the reliability and accordingly the validity of the EEG is restricted by technical problems and limited intrarater stability and interrater agreement.

Brain Death↗
PubMed1988

Serial recording of median nerve stimulated subcortical somatosensory evoked potentials (SEPs) in developing brain death.

Subcortical somatosensory evoked potentials (SEPs) to median nerve stimulation were recorded serially in 35 patients during the evolution towards brain death and in brain death. Neuropathological alterations of the central nervous system down to the C1/C2 spinal cord segment in brain death are well known. SEP components supposed to be generated above this level should be lost in brain death, while components generated below should not be altered. Erb's point, scalp and neck potentials were recorded at C3/4, or over the spinous process C7, using an Fz reference. In 10 patients additional montages, including spinous process C2-Fz, a non-cephalic reference (Fz-contralateral shoulder) and a posterior to anterior neck montage (spinous process C7-jugulum) were used. The cephalic referenced N9 and N11 peaks remained unchanged until brain death. N9 and N11 decreased in parallel in amplitude and increased in latency after systemic effects like hypoxia or hypothermia occurred. The cephalic referenced 'N14' decreased in amplitude and increased in latency after the clinical brain death syndrome was observed, while N13 in the posterior to anterior neck montage remained unchanged. The alteration of 'N14' went parallel to the decrease of the P14 amplitude. The subcortical SEPs in the cephalic referenced lead are supposed to be a peak composed by a horizontally orientated dorsal horn generated N13 and a rostrally orientated P14 arising at the level of the foramen magnum. The deterioration of the non-cephalic referenced P14 and of its cephalic referenced reflection 'N14' seems to provide an additional objective criterion for the diagnosis of brain death.

Brain Death↗
PubMed1988

Evoked potentials in basilar artery thrombosis: correlation with clinical and angiographic findings.

In 28 patients with vertebro-basilar or basilar artery thrombosis brain-stem auditory evoked potentials (BAEPs) and somatosensory evoked potentials (SEPs) have been recorded. Visual evoked potentials (VEPs) were recorded in 7 of these 28 patients. In 24 patients the diagnosis was angiographically proven and in 4 patients Doppler sonography and computerized tomography suggested this diagnosis. The BAEP and SEP findings were correlated to clinical and angiographical signs. BAEPs could be classified into 6 different patterns. In more than half of the patients different BAEP patterns from the two ears could be found. A pathological IV/V complex was most often found in comatose patients and in patients with a basilar artery occlusion distal to the anterior inferior cerebellar artery. Prolonged interpeak latency of I-III was mainly found in alert or drowsy patients with caudal occlusions. The frequent occurrence of a BAEP with only wave I preserved, or with no waves preserved, in patients with brain-stem functions suggests that BAEPs are not useful in the diagnosis of brain death when basilar artery thrombosis is suspected. SEPs were either absent bilaterally or else severely altered on one side in all comatose patients. In alert patients, including those with 'locked-in' syndrome, SEPs were never absent bilaterally. Increased N13-N20 interpeak latency was an uncommon finding in this series. There was no correlation between the SEP and the angiographically proven location of the occlusion. In the 'locked-in' syndrome both SEP and BAEP findings were non-uniform. Normal SEPs were sometimes found in combination with severely altered BAEPs, suggesting partial deafferentation. Since basilar artery thrombosis is now a treatable condition, early diagnosis and documentation of functional deficits moves into a more important clinical area than heretofore.

Adult↗
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

Non-herpes simplex encephalitis is early exclusion of herpes simplex etiology possible?

Since effective antiviral treatment is available for herpes simplex encephalitis (HSE), early diagnosis or exclusion of herpes simplex etiology is essential for prognosis. In a retrospective study of 25 cases of acute viral encephalitis not caused by herpes simplex virus (non-HSE), we investigated whether HSE can be excluded in the early phase before serological evidence is present. Using clinical means, history, investigations of CSF (protein, cells), EEG, and CCT, HSE could not be excluded with reliability. This is because clinical signs and laboratory results are not pathognomonic for any form of viral encephalitis, even if periodic activity in EEG and temporal attenuation in CCT are more frequent in HSE than in other forms of encephalitis. Therefore, in all cases of severe encephalitis, acyclovir therapy should be initiated early.

Adolescent↗
PubMed1987

Vascular recanalizing techniques in the hind brain circulation.

Percutaneous transluminal angioplasty (PTA) was performed in 45 patients with a manifest subclavian steal syndrome. Thirty-five of those patients were subjected to follow up examinations over a period of 6 to 18 months. Five patients suffered from severe restenosis and were treated again. Two thirds of the patients benefited from the treatment. PTA of the proximal vertebral artery was performed in 15 patients with bilateral occlusive lesions of the extracranial vertebral arteries. In 13 of these cases the neurological and the vascular states of the patients were regularly reexamined, 8 showed a marked improvement. During the 2 to 25 month observation period (average 15 months post-PTA) reocclusion was observed in only two cases. These showed no recurrent neurological sequelae. Forty-three consecutive patients with acute vertebro-basilar or basilar occlusion received intraarterial fibrinolytic therapy with streptokinase or urokinase. Twenty-three of these had presented severe deficits at the beginning of therapy (e.g. complete tetraplegia, comatous state for more than 6 hours). None of this group survived. By contrast the 20 other patients in this group presented with incomplete fluctuating or progressive motor deficits. None was comatous for more than 6 hours. Fourteen patients (33% in this group) survived. Local intraarterial fibrinolytic therapy is the only therapy successful in the treatment of progressive stroke from vertebro-basilar thrombosis.

Aged↗
PubMed1987

[Motor potentials following spinal and transcranial stimulation: normal values for recording without voluntary pre-innervation].

The transcranial motor stimulation with a special, short discharging stimulator can assess the conduction of central motor pathways. Voluntary preinnervation of certain muscles leads to amplitude augmentation and allows reduction of the stimulus intensity. Preinnervation is impossible, if comatose patients are studied or if the method is used for intraoperative monitoring. We examined the spinal and transcranial stimulated motor responses of the muscle opponens pollicis without preinnervation in 18 healthy volunteers. The latencies after hemispheric stimulation showed an increase of latency of more than 2.5 ms compared with normative data from the literature which is significant on the .05-level. The central conduction time was prolonged also. The latencies of the spinal stimulated muscle potentials are comparable under both conditions. It is concluded that for intraoperative monitoring or the assessment of motor function in comatose patients one has to relay on normative values achieved without preinnervation.

Adult↗
PubMed1986

Percutaneous transluminal angioplasty of the vertebral artery. A therapeutic alternative to operative reconstruction of proximal vertebral artery stenoses.

Percutaneous transluminal angioplasty (PTA) of the proximal vertebral artery was performed in 13 patients with stenosis of the proximal vertebral arteries. All of these patients had symptoms indicating vertebrobasilar insufficiency. PTA was performed only if an extreme reduction of the total diameter of both vertebral arteries was present. Only 13 patients have fulfilled the strict selection criteria in the last 3 years. All patients were monitored during the procedure by means of continuous-wave Doppler ultrasound and electrophysiological techniques. After PTA their neurological and vascular conditions were serially examined. Of the 13 patients, 8 showed marked improvement of both subjective and objective clinical symptoms. During an observation period of 2-25 months (average: 15 months) reocclusion of the angioplasty was observed in only 2 cases, without any additional neurological sequelae. Electrophysiological and Doppler sonographic monitoring during PTA helped to minimize the risk of angioplasty.

Angioplasty, Balloon↗
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

[Neuroradiologic and surgical treatment of a recurrent angiofibroma supplied by the internal carotid artery].

If blood supply to the brain hemisphere is disturbed following closure of internal homolateral carotid artery tumors of the skull base with involvement of this artery should not be operated on radically. The authors describe the electrophysiological monitoring of cortical evoked somato-sensory potentials. If there is no alteration of the evoked potentials after preliminary reversible blockade of the internal carotid artery this vessel can be definitely closed using a detachable balloon. Thereafter the whole tumor including the carotid artery can be removed. The authors describe a case of juvenile angiofibroma operated on in this way. The combined interventional-neuroradiological and surgical management widens the range of skull base surgery.

Adult↗
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

Transcranial Doppler sonography as a non-invasive guide for the transvascular treatment of an inoperable basilar-artery aneurysm.

This report deals with the successful treatment of a giant aneurysm located at the caudal basilar trunk in a 19-yr old boy. The aneurysm had been declared to be inoperable by several authorities in the field of neurosurgery. A series of neuroradiological interventions was performed in order to block the aneurysm with the help of a detachable balloon or, at least, to induce spontaneous thrombosis of the aneurysm sac by reducing blood flow within the caudal basilar artery. Transcranial Doppler sonography proved to be a helpful guide for therapeutic decision-making from one interventional step to the next in this adventurous field of treatment. The changing sonographic findings of the vertebrobasilar system during the course of the treatment and during the functional tests, as well as the favourable outcome, have made this case worth reporting.

Adult↗
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↗