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  • 1
    Electronic Resource
    Electronic Resource
    Notes and news (1990)
    Springer
    Acta neurochirurgica 104 (1990), S. 164-164 
    Details
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01842838
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  • 2
    Electronic Resource
    Electronic Resource
    Report of the Research Committee of the EANS (1987–1991) (1992)
    Springer
    Acta neurochirurgica 116 (1992), S. 94-95 
    Details
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01540860
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  • 3
    Electronic Resource
    Electronic Resource
    Notes and news (1990)
    Springer
    Acta neurochirurgica 107 (1990), S. 179-179 
    Details
    ISSN: 0942-0940
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01405799
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    CO2 cerebrovascular reactivity as a function of perfusion pressure — a modelling study (1993)
    Springer
    Acta neurochirurgica 121 (1993), S. 159-165 
    Details
    ISSN: 0942-0940
    Keywords: Cerebral blood flow ; autoregulation ; cerebral perfusion pressure ; carbon dioxide ; computer modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A mathematical model is described that demonstrated the properties of cerebral vascular resistance and compliance expressed as a function of cerebral perfusion pressure (CPP) and arterial CO2 partial pressure (PaCO2). The hypercapnic induced shift of the lower limit of autoregulation to a higher range of CPP, as shown by this model, is a useful characteristic that facilitates the differentiation between normal and impaired autoregulation described previously in experimental studies. Dynamic properties of cerebrovascular circulation derived from the relationship between pulse wave of CBF waveform and CPP have been analysed at different levels of PaCO2-phenomenon, being often described as dependence of blood flow velocity pulsatility index on the autoregulatory reserve. The model was also used to interpret interhemispheric asymmetry of CBF reactivity to changes in arterial concentration of CO2 in patients with carotid artery stenosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01809269
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  • 5
    Electronic Resource
    Electronic Resource
    Assessment of Critical Closing Pressure in the Cerebral Circulation as a Measure of Cerebrovascular Tone (1999)
    Springer
    Acta neurochirurgica 141 (1999), S. 1221-1227 
    Details
    ISSN: 0942-0940
    Keywords: Keywords: Intracranial pressure; critical closing pressure; cerebrovascular tone; experiment; animal.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary ¶ Critical closing pressure (CCP) calculated from the blood flow velocity (FV) and arterial blood pressure (ABP) waveforms has been previously reported to be useful in the assessment of the dynamics of cerebral circulation. We investigated the relationship between CCP and intracranial pressure (ICP) and cerebrovascular tone in a model of intracranial hypertension in 22 anaesthetised New Zealand White rabbits during manipulations of arterial CO2, ABP and vasodilatation caused by hypoxia. Recordings were made of FV in the basilar artery, ABP and ICP during subarachnoid infusion of saline. During infusion ICP and CCP were significantly correlated (R=0.68; p〈0.001), but the magnitude of increase in ICP and CCP during infusion were not correlated to each other. Linear regression between the difference: CCP-ICP (representing a factor due to vasogenic tone) and cerebral perfusion pressure (CPP=ABP-ICP) was highly significant (R=−0.87; p〈0.01). Generally, CCP decreased significantly (p〈0.05) with hypercarbia, arterial hypotension and after and post-hypoxia and the difference: CCP-ICP decreased consistently after each vasodilatatory manoeuvre studied.  Our data confirmed the linear relationship between CCP and ICP, and between the difference: CCP-ICP and cerebrovascular tone. However, because the magnitude of increase in ICP was not correlated to magnitude of change in CCP, CCP cannot be use for detection of increasing ICP quantitatively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s007010050422
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  • 6
    Electronic Resource
    Electronic Resource
    Prediction of late ischaemic complications after cerebral aneurysm surgery —use of a mobile microcomputer system for the measurement of pre-, intra-and postoperative cerebral blood flow (1982)
    Springer
    Acta neurochirurgica 63 (1982), S. 37-42 
    Details
    ISSN: 0942-0940
    Keywords: Microcomputer ; cerebral blood flow ; subarachnoid haemorrhage ; cerebral ischaemia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Patients with defective autoregulation of cerebral blood flow are at much greater risk of developing late cerebral ischaemia after intracranial aneurysm surgery. This finding was based on data derived from the intraoperative measurement of the response of the cerebral circulation to hypotension, deliberately induced to assist dissection and clipping of the aneurysm. A preoperative test which gave the same information as the intraoperative measurements might be helpful in predicting the optimal timing of aneurysm surgery. However, the original intraoperative intravenous133Xenon injection method was limited both by the need to analyse the data off-line and the restricted number of runs (up to 6). This paper describes the modifications used, based on the Apple II microprocessor, to obtain values of cerebral blood flow within 6 minutes of the injection of133Xenon with up to 15–20 runs per patient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01728853
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  • 7
    Electronic Resource
    Electronic Resource
    Effect of intraventricular haemorrhage and rebleeding following subarachnoid haemorrhage on CSF eicosanoids (1994)
    Springer
    Acta neurochirurgica 129 (1994), S. 152-157 
    Details
    ISSN: 0942-0940
    Keywords: Cerebrospinal fluid ; eicosanoids ; prostaglandins ; subarachnoid haemorrhage ; thromboxane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary CSF eicosanoid levels are raised following subarachnoid haemorrhage but not sufficiently to be vasoactive per se within the cerebral circulation. Rebleeding and intraventricular haemorrhage are two factors associated with a worse outcome after aneurysmal SAH. We have examined the effects of these two factors on the CSF levels of TXB2 (TXA2 metabolite), PG 6-keto F1α (prostacyclin metabolite), PGF2α and PGE2 in 44 patients following subarachnoid haemorrhage. In 15 patients who had received no non-steroidal antiinflammatory agent or dexamethasone, intraventricular haemorrhage increased the median levels of all four eicosanoids in ventricular CSF by 2.1–5.1-fold. In 4 patients who rebled, the CSF median levels of all four eicosanoids were raised up to 250-fold over the normal range. These concentrations are just sufficient to have cerebrovascular and neuromodulatory effects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01406495
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  • 8
    Electronic Resource
    Electronic Resource
    Changes in transcranial Doppler flow velocity waveform following inhibition of nitric oxide synthesis (1997)
    Springer
    Acta neurochirurgica 139 (1997), S. 63-70 
    Details
    ISSN: 0942-0940
    Keywords: Transcranial Doppler ; cerebrocortical microcirculation ; basilar artery ; nitric oxide ; rabbits
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Background Analysis of the transcranial Doppler blood flow velocity (FV) waveform is used clinically to detect changes in cerebral haemodynamic profile. Such changes may be initiated both by alterations in microvascular resistance and in the tone of the cerebral arteries. Methods The role of endothelial mechanisms was investigated using inhibition of NO synthesis by systemic administration of NG-nitro-L-arginine methyl ester (L-NAME, 6 mg/kg) followed by simultaneous monitoring of both basilar artery FV and cerebrocortical microcirculation (laser Doppler flowmetry, LDF) in aneasthetised, ventilated rabbits over 60 minutes. Results Arterial blood pressure (AP) increased significantly (p 〈 0.01) above baseline level in the second minute following L-NAME and remained elevated until the end of experiment. Time average mean and systolic FV decreased immediately following L-NAME injection, with the statistically significant (p 〈 0.01) decrease from the third minute. Diastolic FV did not show such radical changes. LDF exhibited a slow decrease with time becoming significantly lower than baseline (p 〈 0.01) at 50 min. Conclusion A gradual decrease in cortical microcirculation preceded by a rapid reaction recorded in the TCD waveform implies that an increase in the tone of the great cerebral arteries is the predominant phenomenon seen during the acute phase of NO synthase inhibition.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01850870
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  • 9
    Electronic Resource
    Electronic Resource
    Significance of intracranial pressure waveform analysis after head injury (1996)
    Springer
    Acta neurochirurgica 138 (1996), S. 531-542 
    Details
    ISSN: 0942-0940
    Keywords: Head injury ; intracranial pressure ; monitoring ; outcome ; waveform analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors have investigated the relationships between the amplitude of the ICP pulse wave, the mean values of ICP and CPP, and the outcome of 56 head injured ventilated patients. The ICP was monitored continuously using a Camino transducer (35 patients) or subdural catheter (21 patients). The mean Glasgow Coma Score was 6 (range 3–13; 5 patients had a GCS 〉 8 after resuscitation). Patients were grouped according to their Glasgow Outcome Score assessed at 12 months after injury. The amplitude of ICP pulse waveform was assessed using the fundamental harmonic of the pulse waveform (AMP) to avoid distortion caused by different frequency responses of the pressure transducers used in the study. Statistical analysis revealed that in patients with fatal outcome the ICP pulse amplitude increased when the mean ICP increased to 25 mmHg and then began to decrease. The upper breakpoint of the AMP-ICP relationship was not present in patients with good/moderate outcome. The moving correlation coefficient between the fundamental harmonic of ICP pulse wave and the mean ICP (RAP: R-symbol of correlation between A-amplitude and P-pressure) was introduced to describe the time-dependent changes in correlation between amplitude and mean ICP. The RAP was significantly lower in patients who died or remained in the vegetative state. In 7 patients who died from uncontrollable intracranial hypertension RAP was oscillating or decreased to 0 or negative values well before brain-stem herniation. The combination of an ICP above 20 mmHg for a period longer than 6 hours with low correlation between the amplitude and pressure (RAP 〈 0.5) was described as an predictive index of an unfavourable outcome.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01411173
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  • 10
    Electronic Resource
    Electronic Resource
    Shunt audit: A computerized method for testing the performance characteristics of CSF shunts in vitro (1994)
    Springer
    Child's nervous system 10 (1994), S. 158-161 
    Details
    ISSN: 1433-0350
    Keywords: CSF shunts ; Performance characteristics ; Differential pressure ; Flow rate ; Stability ; Computer control
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Studies of long-term shunt performance in vivo demonstrate that some 81% fail within 12 years. Such failure is multifactorial in origin: the patient, the surgical technique and the shunt may all prove fallible. Recent studies have shown that there is considerable variability of the performance characteristics of individual shunts when tested for short time periods in relatively simple rigs, and that they do not always behave according to the manufacturers' specifications. We have developed a computerized shunt rig for the longterm evaluation of a valve's performance in vitro using both pressure-flow studies (where flow through the shunt is evaluated for controlled differential pressure across the shunt) and flow-pressure studies (where the differential pressure across the shunt is evaluated for controlled flow rates through the shunt). This rig consists of a pressure transducer, electronic balance, computer-controlled infusion pump and blood pressure systems calibrator that stimulates different wave form patterns. An IBM PC controls all the devices and evaluates the performances characteristics according to various test protocols. Our initial observations with this rig confirm that progressive changes in shunt function occur over long periods of time (weeks).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00301082
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    Paper (German National Licenses)
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