Biomedical subjects

Dariusz Latka

Publications and source records attributed to Dariusz Latka.

6 recordsLinked to original sources

PubMed2007

Noninvasive measurement of intracranial pressure: is it possible?

BACKGROUND: Some publications suggest a strong correlation between the intracranial pressure and the intraocular pressure. Other studies claim no correlation between these two physiologic variables. Our aim was to study whether the tonometry could be a useful method to evaluate intracranial pressure in patients with suspected intracranial abnormality. METHODS: We evaluated the correlation between the intracranial pressure and the intraocular pressure, the intracranial pressure and the mean arterial pressure, and the intraocular pressure and the mean arterial pressure in 22 patients, initially comatose, who were admitted to our hospital. All patients required the intracranial pressure monitoring on clinical grounds. Simultaneous measurements were performed and recorded. RESULTS: We calculated both the linear correlation coefficient and the Spearman rank-order correlation coefficient. We found significant correlation between the intraocular pressure and the mean arterial pressure in 12 patients; however, significant correlation between the intraocular pressure and the intracranial pressure was found in only 2 patients. CONCLUSION: Tonometry is not an appropriate method for the assessment of intracranial pressure increases.

Adult↗

PubMed2005

Phase dynamics in cerebral autoregulation.

Complex continuous wavelet transforms are used to study the dynamics of instantaneous phase difference delta phi between the fluctuations of arterial blood pressure (ABP) and cerebral blood flow velocity (CBFV) in a middle cerebral artery. For healthy individuals, this phase difference changes slowly over time and has an almost uniform distribution for the very low-frequency (0.02-0.07 Hz) part of the spectrum. We quantify phase dynamics with the help of the synchronization index gamma = (sin delta phi)2 + (cos delta phi)2 that may vary between 0 (uniform distribution of phase differences, so the time series are statistically independent of one another) and 1 (phase locking of ABP and CBFV, so the former drives the latter). For healthy individuals, the group-averaged index gamma has two distinct peaks, one at 0.11 Hz [gamma = 0.59 +/- 0.09] and another at 0.33 Hz (gamma = 0.55 +/- 0.17). In the very low-frequency range (0.02-0.07 Hz), phase difference variability is an inherent property of an intact autoregulation system. Consequently, the average value of the synchronization parameter in this part of the spectrum is equal to 0.13 +/- 0.03. The phase difference variability sheds new light on the nature of cerebral hemodynamics, which so far has been predominantly characterized with the help of the high-pass filter model. In this intrinsically stationary approach, based on the transfer function formalism, the efficient autoregulation is associated with the positive phase shift between oscillations of CBFV and ABP. However, the method is applicable only in the part of the spectrum (0.1-0.3 Hz) where the coherence of these signals is high. We point out that synchrony analysis through the use of wavelet transforms is more general and allows us to study nonstationary aspects of cerebral hemodynamics in the very low-frequency range where the physiological significance of autoregulation is most strongly pronounced.

Adult↗

PubMedDate not supplied

[Fractal analysis of MCA blood flow velocity fluctuations in migraine--preliminary report].

Many reports confirm the existence of long-range correlations between fluctuations of various physiological signals in healthy subjects and demonstrate disappearance of these correlations in pathological conditions. Blood flow velocity in intracranial vessels is changeable over time and depends on complex physiological regulatory mechanisms. The character of blood flow velocity fluctuations may indicate the presence of vascular disorders associated with various diseases. The aim of our study was to establish whether fluctuations in MCA blood flow velocity are fractal in physiological conditions and if so, whether this feature is lost in migraine, as the role of vasomotoric disturbances has been already evidenced in pathophysiology of this disease. The axial flow velocity changes averaged over a cardiac beat interval were monitored continuously via two channels through the temporal windows using a DWL Multi-DopT TCD device with 2-MHz probes. The examinations were performed in supine rest in two-hour periods in two groups: of 7 patients with clinically confirmed migraine with aura during headache-free intervals (15 recordings), and in the control group of 4 young, healthy volunteers (10 recordings). The results in the form of time series were analysed using the methods of fractal statistics. Multifractality in the recordings in physiological conditions was clearly confirmed, as well as its absence in the averaged recordings in the group of migraneurs. The findings justify a supposition that the breakdown of multifractal properties of MCA blood flow time series in migraine may result from the vasomotor disturbances present even during headache-free intervals. However, possible usefulness of this method in the diagnostics of migraine requires further investigation.

Adolescent↗

PubMedDate not supplied

[Fractal analysis of intracranial blood flow velocity fluctuations in continuous TCD recordings].

Many physiological signals fluctuate in an apparently irregular and complex manner. The fractal analysis of these changes often confirms the existence of long-range correlations in healthy subjects and demonstrate a lack of such correlations in pathological conditions. The authors discuss usefulness of the fractal statistics methods in the analysis of intracranial blood flow velocity changes averaged over a cardiac beat interval measured in humans, using transcranial Doppler ultrasonography (TCD). An assumption was made that fractal properties of blood velocity time series in healthy individuals result from a proper autoregulation of their cerebral blood flow and that in cases of vascular disturbances fractuality may disappear. A review of the literature is presented to provide a theoretical rationale for the proposed method.

Blood Flow Velocity↗

PubMedDate not supplied

[Abduction of the eyeballs palsy as a first sign of subarachnoid hemorrhage from ruptured posterior inferior cerebellar artery aneurysm: a case report].

The authors present a rare case of the abduction of the eyeballs palsy caused by subarachnoid hemorrhage from ruptured posterior-inferior cerebellar artery aneurysm, which appeared as a first sign of hemorrhage. Aneurysm was clipped. During three days after the operation, oculomotor lesions appeared persistent, no consciousness deterioration or other focal signs were observed. On the third day after the operation asystolic cardiac arrest appeared. Control CT scan did not reveal any pathological changes responsible for such deterioration. The patient died. In our case after an analysis of the mechanism and pathophysiology of this lesion in our opinion that palsy might be caused by influence of extravasated blood after hemorrhage. This thesis is adequate to the reviewed literature on this problem. Nevertheless, the compression of the abducent nerve as the reason cannot be excluded, e.g. rapid enlargement of the aneurysm or the compression of the brain stem near the nerve. Posthemorrhagic lesion of the brain stem may have been the reason of this lesion, caused by penetration of the blood into the ventricle during subarachnoidal hemorrhage. Although these lesions are very rare, subarachnoid hemorrhage should be taken into consideration when the patient with eyeballs abduction palsy is admitted to a neurosurgical or neurological department.

Abducens Nerve Diseases↗

PubMedDate not supplied

[A rare case of chondromyxoid fibroma of the parietal bone].

The authors present a very rare case of the chondromyxoid fibroma (CMF) of the parietal bone. This is an uncommon chondroid tumour which constitutes less than 1% of primary bone tumours and which is usually localised in the metaphysis of the long bones, often in the knee region. There are 23 cases of cranial localisation of the chondromyxoid fibroma reported in several papers, 14 cases involved the cranial base and 9 the calvaria. A different ossification process of the skull-base and calvaria is probably responsible for this distribution. In our case we found the focal, lytic lesion in the parietal bone and fibro-greasy tumour mass. The dura was spared. The tumour was removed totally. Curettage of these kind of lesions should be avoided because it may lead to tumour recurrence. Histologically this tumour may cause problems in a differential diagnosis with other chondroid tumours like chondrosarcoma or chondroblastoma.

Adult↗