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Biomedical subjects

A Ferbert

Publications and source records attributed to A Ferbert.

At least 55 records · Page 3Linked to original sources
PubMed1992

Recombinant tissue plasminogen activator in acute thrombotic and embolic stroke.

An open angiography-based, dose rate escalation study on the effect of intravenous infusion of recombinant tissue plasminogen activator (rt-PA) on cerebral arterial recanalization in patients with acute focal cerebral ischemia was performed at 16 centers. Arterial occlusions consistent with acute ischemia in the carotid or vertebrobasilar territory in the absence of detectable intracerebral hemorrhage were prerequisites for treatment. After the 60-minute rt-PA infusion, arterial perfusion was assessed by repeat angiography and computed tomography scans were performed at 24 hours to assess hemorrhagic transformation. Of 139 patients with symptoms of focal ischemia, 80.6% (112) had complete occlusion of the primary vessel at a mean of 5.4 +/- 1.7 hours after symptom onset. No dose rate response of cerebral arterial recanalization was observed in 93 patients who completed the rt-PA infusion. Middle cerebral artery division (M2) and branch (M3) occlusions were more likely to undergo recanalization by 60 minutes than were internal carotid artery occlusions. Hemorrhagic infarction occurred in 20.2% and parenchymatous hematoma in 10.6% of patients over all dose rates, while neurological worsening accompanied hemorrhagic transformation (hemorrhagic infarction and parenchymatous hematoma) in 9.6% of patients. All findings were within prospective safety guidelines. No dose rate correlation with hemorrhagic infarction, parenchymatous hematoma, or both was seen. Hemorrhagic transformation occurred significantly more frequently in patients receiving treatment at least 6 hours after symptom onset. No relationship between hemorrhagic transformation and recanalization was observed. This study indicates that site of occlusion, time to recanalization, and time to treatment are important variables in acute stroke intervention with this agent.

Acute Disease↗
PubMed1992

Bilateral anterior cerebral artery territory infarction in the differential diagnosis of basilar artery occlusion.

Two patients with bilateral anterior cerebral artery (ACA) territory infarction are presented whose initial diagnosis was basilar artery occlusion. Both had tetraparesis; in one it was asymmetrical. Both had their eyes open and did not respond to command except that after a delay they followed with their eyes a smoothly moving object; this was the only sign of awareness. One patient had a clear vertical gaze palsy in the upward and downward direction unaccompanied by pupillary abnormalities. Computed tomography revealed fresh bilateral ACA infarction in both patients; occlusion in the hind brain circulation was excluded by angiography in one. Both patients suffered from atrial fibrillation, so cardiac embolism was the most likely cause of the stroke. We conclude that bilateral ACA territory infarction should be considered in the differential diagnosis of basilar artery occlusion, even if accompanied by vertical gaze palsy.

Aged↗
PubMed1992

German-Austrian Space Occupying Cerebellar Infarction Study (GASCIS): study design, methods, patient characteristics. The Steering and Protocol Commission.

An open prospective multicentric therapeutic trial to determine the timing and type of therapeutic intervention in patients presenting with secondary deterioration following cerebellar stroke is described. According to the results of retrospective studies a controlled approach comparing different therapies is ethically not feasible. Participants use the same scores and protocol for patient data collection but many choose different therapeutic procedures.

Austria↗
PubMed1992

Non-traumatic subarachnoid hemorrhage with normal angiogram. Long-term follow-up and CT predictors of complications.

We investigated 91 patients with non-traumatic subarachnoid hemorrhage (SAH) in whom no aneurysm was found on initial angiography. In 31 of these patients CT did not show subarachnoid blood. A typical feature was a localized blood clot in the prepontine or interpeduncular cistern. Follow-up was obtained 6 months to 11.8 years after SAH by personal re-examination (n = 49) or questionnaire sent to patients or their doctors. 79 patients were free of neurological signs, 3 had a mild and one a severe neurological deficit. Five patients had died from SAH. Those patients who died or had complications often had blood in the frontal basal interhemispheric fissure. None of the 3 therapeutic regimens applied proved to be superior. We conclude that prognosis is good, but an unidentified aneurysm must be considered and repeat angiogram is warranted if blood is found in the anterior part of the basal cisterns. When the hemorrhage is in the prepontine cistern, repeat angiogram is not necessary.

Adult↗
PubMed1992

Cortical projection to erector spinae muscles in man as assessed by focal transcranial magnetic stimulation.

We stimulated the motor cortex in 9 subjects using focal transcranial magnetic stimulation with a figure of 8 coil in order to examine the cortical representation of the erector spinae muscles. Recordings were made from the erector spinae 3.5 cm lateral to the third lumbar vertebra. In 5 subjects clearly reproducible responses could be obtained which had a latency compatible with transmission via fast conducting fibers in a mono- or oligosynaptic pathway. In the remaining 4 subjects responses were poorly defined. Latencies in surface recordings varied between 13 and 24 msec but were longer when needle recordings were used. Mapping of the motor cortex was performed by moving the coil in 2 cm steps on either side of Cz. Different patterns of hemispheric representation were found ranging from a contralateral projection in either hemisphere to a representation of both back muscles in one hemisphere (2 subjects). Responses were followed by a silent period. The latter was interrupted or terminated by a response between 52 and 85 msec post stimulus which was found predominantly in the muscle ipsilateral to the side of stimulation.

Adult↗
PubMed1992

Interhemispheric inhibition of the human motor cortex.

1. Using two magnetic stimulators, we investigated the effect of a conditioning magnetic stimulus over the motor cortex of one hemisphere on the size of EMG responses evoked in the first dorsal interosseous (FDI) muscle by a magnetic test stimulus given over the opposite hemisphere. 2. A single conditioning shock to one hemisphere produced inhibition of the test response evoked from the opposite hemisphere when the conditioning-test interval was 5-6 ms or longer. We shall refer to this as interhemispheric inhibition. However, the minimum latency of inhibition observed using surface EMG responses may have underestimated the true interhemispheric conduction time. Single motor unit studies suggested values 4-7 ms longer than the minimum interval observed with surface EMG. 3. Interhemispheric inhibition was seen when the test muscle was active or relaxed. Increasing the intensity of the conditioning stimulus increased the duration of inhibition: increasing the intensity of the test stimulus reduced the depth of inhibition. 4. The conditioning coil had to be placed on the appropriate area of scalp for inhibition to occur. The effect of the conditioning stimulus was maximal when it was applied over the hand area of motor cortex, and decreased when the stimulus was moved medial or lateral to that point. 5. The inhibitory effect on the test stimulus probably occurred at the level of the cerebral cortex. In contrast to the inhibition of test responses evoked by magnetic test stimuli, test responses evoked in active FDI by a small anodal electric shock were not significantly inhibited by a contralateral magnetic conditioning stimulus. Similarly, H reflexes in relaxed forearm flexor muscles were unaffected by conditioning stimuli to the ipsilateral hemisphere. However, inhibition was observed if the experiment was repeated with the muscles active.

Adult↗
PubMed1992

Transcranial magnetic stimulation in pontine infarction: correlation to degree of paresis.

Transcranial magnetic stimulation was performed in 20 patients with pontine infarction who had initially some degree of hemiparesis. Only patients with a well defined lesion on magnetic resonance imaging that was appropriate for the neurological signs were included. Recordings were made from the abductor pollicis brevis muscle (APB) bilaterally. The degree of hand paresis was estimated clinically and related to the following parameters: central motor conduction time (CMCT), interside latency difference of total latency, and amplitude ratio of affected to unaffected side. Increasing degree of paresis was associated with increasing latency parameters and decreasing amplitude ratio. In the four patients with severe paresis a low amplitude response could be evoked and CMCT was delayed by up to 10 ms. When the paresis had resolved at the time of transcranial magnetic stimulation CMCT was normal. However, amplitude ratio was less than 100% in all but one patient, with most of the values ranging between 40% and 60%, which indicates a subclinical pyramidal tract lesion. Median nerve sensory evoked potentials (SEP) and related interside latency difference to amplitude ratio N20/P25 were also recorded. In contrast to TCMS, decreased amplitude ratio of SEP was not associated with delayed latency. Clinically, the mild degree of and good recovery from paresis in ventral pontine infarction was remarkable.

Adult↗
PubMed1992

[Damage to the lateral cutaneous femoral nerve after transfemoral angiography].

We report on two patients with lesions of the lateral cutaneous nerve of the thigh after transfemoral angiography. Symptoms were hypesthesia, dysesthesia and hypalgesia of the right lateral thigh. One patient had no hematoma, the other a hematoma of the medial thigh which did not enlarge thigh circumference. Both patients had had a tight pressure bandage applied for 24 hours. There were no signs of a femoral nerve lesion. Both patients were severely distressed by paresthesia. The numbness subsided after three weeks in one patient, but pain persisted. The other patient had symptoms for over six months. The lateral cutaneous nerve of the thigh is located distinctly lateral to the puncture site in transfemoral angiography. Hence we suggest that the nerve lesion was caused neither by the puncture itself nor by a hemorrhage, but by the tight bandage.

Aged↗
PubMed1992

[Topography of early cortical median nerve somatosensory evoked potentials: results for routine use of the method].

The results from a topographic analysis of the early median nerve SEPs allowed to design a method for recording and analysing the SEPs in the routine laboratory. The detailed analysis of the topography of 50 normal subjects revealed: 1. An inter- and intraindividual variability of the location of the maximal amplitudes, 2. A significantly longer latency of the cortical potentials after left side stimulation, 3. A significantly higher amplitude of N20 after left side stimulation and 4. A significantly higher amplitude of the later potentials P25 and N30 after right side stimulation. It was shown that a 4-channel recording from the neck at C7 with a Fz-reference as well as from stimulus contralateral F3, CP3 and P3 or F4, CP4 and P4 with an stimulus contralateral earlobe reference provides all necessary parameters in comparison to an 20-channel recording. The definition of normal values has to take into account these results. Absolute maximum values were taken instead of the standard deviation because all amplitude values were proven to be not distributed normally. In 7 out of 30 MCA-stroke patients pathological SEP amplitudes were obtained using the 4-channel montage, whereas the 1-channel recording from CP3 and CP4 with a Fz-reference revealed normal amplitudes.

Adult↗
PubMed1992

[Spatial distribution of the action potentials of the sural nerve].

We investigated the spatial distribution of the sural nerve sensory nerve action potential (SNAP) in 25 healthy subjects between 21 and 50 years. Stimulation was achieved through surface electrodes at the lateral malleolus. Recordings were made 15-18 cm proximal to the site of the stimulation from different positions on a line perpendicular to the sural nerve using needle electrodes insulated except for the tip. The amplitude of the SNAP decreased on both sides of the potential of highest amplitude. 10 mm lateral to the potential of highest amplitude the mean amplitude was reduced to 55%. The latency of the first positive phase decreased within increasing distance from the largest SNAP. We explained this with different influence of more distal, earlier depolarized nerve segments on the locally generated SNAP. In 20 subjects we performed an additional recording using an uninsulated needle electrode that was placed 3-4 cm subcutaneously perpendicular to the sural nerve. The latency of the SNAP recorded in this way was similar to the latency of the largest SNAP using the insulated needle electrode; however, the amplitude was smaller by 19%. We recommend for clinical practice to use the uninsulated needle in case the SNAP is smaller than 4 microV.

Action Potentials↗
PubMed1992

[Excitability of the blink reflex during self-elicitation or elicitation by others].

Electrically evoked blink reflexes were studied in 24 healthy subjects in different conditions of elicitation. In one condition the electrical shock was delivered by the experimenter; in a second condition the subject triggered the stimulus himself by manually operating a switch. The different conditions were investigated relaxed or clenching the fist with left hand. Moreover, in 3 subjects the stimulus was given in various delays after the occurrence of the EMG activity of the forearm flexor muscles due to a ballistic wrist flexion. The latencies and peak to peak amplitudes of the ipsi- and contralateral early and late responses were analysed. Voluntary sustained contraction of the left hand (fist) caused no significant modification of the blink reflex. Self-triggering of the stimulus had a facilitating influence on the early components (R1, R1') and an inhibitory effect on the late components (R2, R2'). In EMG triggered self-stimulation the R2-inhibition could already be seen at a delay of 0 ms. From a delay of 10 ms on the suppression was still more pronounced and recovered over the following 500-1000 ms. We conclude, that the reflex alterations are not due to the outflow of the motor cortex, but to the conditioning effect of self-elicitation. The influence on the excitability of the blink reflex resemble that described in the literature for the conditioning effect of an acoustic or visual stimulus. We suggest involvement of the same interneuron network on the condition of self-eliciting.

Adult↗
PubMed1992

High frequency vibration induced gating of subcortical and cortical median nerve somatosensory evoked potentials: different effects on the cervical N13 and on the P13 and P14 far-field SEP components.

Subcortical and cortical somatosensory evoked potentials (SEP) to median nerve stimulation were recorded before, during and after high frequency (270 Hz) vibration of the fingers 1-3 in 8 healthy subjects. A marked decrease of the amplitude of all potentials was observed. The attenuation of the sensory nerve action potential (SNAP) of the median nerve and the attenuation of SEP components N9, N11 and N13 showed no differences, while the attenuation of the subcortical P14 component was significantly higher. This is in accordance with a generator of the cervical N13 in the interneurons beside the lemniscal pathway. The cortical N20 (post-rolandic) was significantly more decreased in amplitude than P14 while P22 (pre-rolandic) remained reduced in amplitude like P14. An increased latency of the far-field subcortical P14 was observed, while P13 recorded in the same montage remained unchanged in latency. These findings suggest different generators of these peaks. A generator of P14 above the nucleus cuneatus is confirmed. A presynaptic generator of P13 is suspected.

Action Potentials↗
PubMed1991

Hereditary motor and sensory neuropathy (HMSN) and optic atrophy (HMSN type VI, Vizioli).

Clinical and electrophysiological findings are described in three patients with hereditary motor and sensory neuropathy in association with optic atrophy (HMSN VI). The optic atrophy was of the Leber type in a 15-year-old boy. In a 70-year-old patient, as in three members of his family, optic atrophy was associated with tapetoretinal degeneration. In addition to HMSN and optic atrophy a 20-year-old man suffered from sensorineural deafness. Electrophysiological studies indicated a neuronal form of neuropathy, as in HMSN II. Brainstem auditory evoked potentials also revealed subclinical involvement of the central auditory pathways in the patients without hearing defects.

Adolescent↗
PubMed1991

Short-term memory performance with magnetic stimulation of the motor cortex.

Whether transcranial magnetic stimulation of the motor cortex has an influence on memory was investigated. In a first experiment with 21 healthy volunteers six pronounceable nonsense words were visually presented, immediately followed by a magnetic stimulus. There were three blocks of stimulation with field intensities of 60, 80 and 100% (referring to a maximal intensity of 2 Tesla), each block comprising six magnetic stimuli and six nonsense words. After each block there was a free recall test and at the end another free recall trial as well as a multiple-choice recognition test for all 18 words. Eighteen subjects served as controls, undergoing the same procedure, except that the field intensity was zero. A significant but small reduction of short-term memory performance was observed only for 100% field intensity. In a second experiment with 16 subjects who had not participated in experiment I, the effect of 100% intensity cortical magnetic stimulation was compared with a control stimulation over the cervical spine. There was no difference in free recall or in the multiple-choice test between the sites of stimulation, suggesting that the difference in the 100% intensity block in experiment I was not due to a specific cortical effect of the magnetic field on memory function. With respect to the effect on memory functions, transcranial magnetic stimulation of the motor cortex is thought to be a safe method.

Adult↗
PubMed1991

Intercostolumbar spinal nerve anastomosis. An experimental study in dogs.

End-to-end anastomoses were done between the motor roots of T12 and T13 intercostal nerves and the ipsilateral transsected L1 lumbar nerve in four dogs. In three of the dogs, the clinical and electrophysiologic findings showed functional viability of the intercostolumbar anastomosis 3.5 months after the anastomosis was done. The method may be practical for reinnervating an injured lumbar nerve with two intercostal nerves or to bypass a spinal cord lesion.

Abdominal Muscles↗
PubMed1991

Microinfarction in classic migraine? A study with magnetic resonance imaging findings.

By means of magnetic resonance imaging we investigated a total of 45 patients suffering from classic migraine; 25 patients had been treated in our department for classic migraine over the past 2 years (group A), and 20 other patients investigated between 1976 and 1984 were reexamined for this study (group B). Thirty-two age- and roughly sex-matched healthy volunteers underwent magnetic resonance imaging and served as controls (group C). There was a trend for patients with classic migraine to have more subcortical patchy lesions on T2-weighted magnetic resonance imaging. In a comparison of our control subjects and patients with a history of greater than 20 attacks of classic migraine taken from groups A and B, this difference in number of lesions was significant (p = 0.02). The results suggest that patchy lesions in patients with classic migraine should be interpreted with particular caution before diagnosing a demyelinating disease since the lesions could be ischemic in origin.

Adult↗