[Evaluation of a Combination of Waveform Amplitude Latency and Decrease of Waveform Amplitude Magnitude during Spinal Surgery in Intraoperative Neurophysiological Monitoring of Transcranial Motor Evoked Potentials and Its Incidence on Postoperative Neurological Deficit]. / Vplyv predlzenia latencie transkraniálnych motorických evokovaných potenciálov v korelácií so znízením amplitúdy pocas spinálnych operácií s pouzitím intraoperacného neurofyziologického monitoringu na prognózu pooperacného neurologického deficitu.

PURPOSE OF THE STUDY This retrospective study investigated the significance of a combination of peak latency of waveform amplitude and waveform amplitude in association with spinal deformities. The correlation with postoperative neurologic deficit was evaluated too. MATERIAL AND METHODS Between January 2007 and January 2018, a group of 113 patients was evaluated in the study who underwent spine surgery using intraoperative neurophysiological monitoring (IONM) focusing on transcranial motor evoked potential (tc-MEP) monitoring. The average age of the patients was 30 years. Tc-MEPs were recorded bilaterally from tibialis anterior muscle and the abductor hallucis muscle in 88 patients without neurological deficit and in 25 patients with neurological deficit. The peak latency of waveform amplitude was defined as the period from stimulation until the waveform amplitude reached its peak. The correlation with postoperative neurological deficit was examined separately for latency delays of 5% and 10% or more and in combination with a decrease in amplitude of 70% or more. We used the presence-absence paradigm to evaluate the disappearance of previously present tc-MEPs and amplitude latency delays. The correlation with the deterioration of amplitudes from baseline or the elevation of thresholds was not used. Statistical tests were used to investigate the changes. The cases in our study with significant tc-MEP alerts were reviewed against the evidence-based response checklist. RESULTS Of 113 patients, the decrease in amplitude of 70% or more was identified in the neurological deficit group in 64% vs. 36% in the normal neurological group (p < 0.001). The neurological deficit was observed in 7.96% of patients postoperatively. A decrease in intraoperative amplitude of 70% or more from previously present tc-MEP occurred in 40 cases, with 89% sensitivity, 64% specificity, 36% false positive rate (FPR), and 20% positive predictive value (PPV) for prediction of postoperative neurological deficit. The amplitude latency peak delay of 10% or more was observed in 41 cases from the group of patients with postoperative neurological deficit, with 100% sensitivity, 64% specificity, 36% FPR and 22% PPV. A combination of a decrease in amplitude of 70% or more from the previously present tc-MEP and a delay in amplitude latency peak of 10% or more resulted in 100% sensitivity, 49% specificity, 51% FPR and 10% PPV in the group of postoperative neurological deficit patients. DISCUSSION Intraoperative tc-MEP alarm points have previously focused mainly on waveform amplitude. In our series, a criterion of an amplitude decrease of 70% or more from previously present tc-MEP was set as the alarm point. No alarm criterion for delay of peak latency of waveform amplitude was set before. We set a latency peak delay of 5% or more and 10% or more of waveform amplitude compared with the previously present tc-MEP as alarm criteria. This is the first study exploring the issue. We demonstrated the efficacy of latency peak of waveform amplitude together with the decrease of waveform amplitude. Another study found similarities in the decrease of amplitude of 70 % or more from baseline and the delay in amplitude latency of 10% or more from baseline; with 86% sensitivity, 98% specificity, 2% FPR and 86% PPV (1). CONCLUSIONS In conclusion, we investigated the efficacy of a change of peak latency delay of waveform amplitude in tc-MEP monitoring. The utilizing of the peak latency delay of waveform amplitude value resulted in high sensitivity up to 100 % and allows reduction of the FPR and an increase of the PPV. Further studies should set the alarm criteria more precisely for the waveform amplitude latency peak delay to achieve more effective spinal cord tc-MEP monitoring. Our concept of findings supports the neurophysiological monitoring findings in other studies. Key words: monitoring, IONM, intraoperative neurophysiological monitoring, tc-MEP, motor evoked potential, transcranial, amplitude, latency, peak.

The influence of anesthesia on intraoperative neurophysiological monitoring during spinal surgeries.

BACKGROUND: Intraoperative neuromonitoring using tc-MEPs satisfactorily detects motor tract integrity changes during spinal surgery. However, tc-MEP is affected by anesthesia and other factors, in which the stimulation threshold increases because the waveform amplitude decreases over time with the accumulation and boluses of anesthetics. METHODS: We conducted a retrospective study of 139 patients. The average age was 30 years. Tc-MEPs were recorded bilaterally from the tibialis anterior muscle and the abductor hallucis muscle. Statistical tests were used to investigate the changes to evaluate anesthetic effects. RESULTS: There were no significant differences in tc-MEP amplitude change (%) between the groups of propofol (13 %), remifentanil (22 %) and sufentanil (26 %, p < 0.01). Significant differences were found between the groups of propofol, remifentanil, and sufentanil (20 %) and bolus sufentanil (‒30 %), and bolus ketamine (730 %, p < 0.008). Major differences were observed between bolus sufentanil (‒30 %) and bolus ketamine (730 %, p < 0.001). When comparing tc-MEPs with no amplitude, no significant difference was found between the groups of propofol (26 %), remifentanil (24 %), and sufentanil (28 %, p < 0.007). Substantial difference was found between the groups of propofol, remifentanil, and sufentanil (mean 26 %) and the group where ketamine boluses were administered. We didn't observe any loss of amplitude (0 %, p < 0.0002). CONCLUSION: IONM may be useless in patients where boluses of sufentanil are administered and also with Medical Research Council grades 3 and below. Consider applying IONM in patients with severe spinal deformity along with a higher age of over 50 and neurological deficit. Increasing stimulus intensity or facilitation techniques may be considered to improve the usefulness of tc-MEP. Our concept of findings supports the neurophysiological monitoring findings in other studies (Tab. 10, Ref. 45).

[Position variability of the vermiform appendix and effect on diagnosis of appendicitis in children]. / Variabilita polôh apendix vermiformis a vplyv na diagnostiku apendicitídy u detí.

Vermiform appendix, seemingly inconspicious anatomical structure, may cause many complications. These result from its topographico-anatomical relations to surrounding structures in abdominal cavity, but also from potential position variability of the vermiform appendix. Variable position of the vermiform appendix can have effect on appendicitis diagnostic, as one of the most often cause of the acute abdomen in children.

The detection of circulating tumor cells expressing E6/E7 HR-HPV oncogenes in peripheral blood in cervical cancer patients after radical hysterectomy.

The aim of this study was to establish the sensitive, specific and clinically acceptable method for detection of tumor cells (TCs) circulating in peripheral blood (PB) of cervical cancer patients without the clinically detectable risk of disease progression. The 7.5 ml of PB of healthy donor was spiked with 5 to 100 cells from SiHa or HeLa cell lines. The spiked tumor cells were collected without gradient centrifugation, by standard gradient centrifugation or by modified gradient centrifugation combined with immunomagnetic separation using EpCAM antibody with affinity for epithelial cell adhesion molecule. The number of collected TCs was determined by EpCAM-FITC-staining and their viability was detected by nested RT-PCR amplifying E6/E7 HR-HPV 16 or HR-HPV 18 oncogenes. For the technical validation of this approach the TCs separation and RT-PCRs were repeated several times. The recovery of viable TCs was reproducibly higher using modified gradient centrifugation combined with immunomagnetic separation in comparison with standard approach. The recovery of TCs in low number of spiked TCs (range from 5 - 20 TCs in 7.5 ml of PB) using modified gradient centrifugation was not reproducible. The recovery of TCs in higher number of spiked TCs (25 TCs and more in 7.5 ml of PB) was reproducible with average recovery about 50 %. The sensitivity of nested RT-PCR amplifying E6/E7 oncogenes was decisively influenced by the number of recovered TCs and the amount of cDNA introduced to RT-PCR, as well. Using this approach we were allowed to detect circulating TCs (CTCs) in cervical cancer patients without metastases, thus this procedure might become a tool to early estimation of disease progression. According to our knowledge, this is the first report describing the use of EpCAM antibody for CTCs detection in cervical cancer patients.

The microscopical structure of the hippocampus in the rat.

The aim of this work was to study the rat's hippocampal formation by applying the light microscopic methods. The histological methods used to explore this region of the rat's brain were the Nissl technique, the Bielschowsky block impregnation method and the rapid Golgi technique. In the Nissl preparations, we identified only three fields of the hippocampus proprius (CA1, CA3 and CA4). CA2 was distinguished in the Bielschowsky impregnated blocks. The rapid Golgi technique, according the available literature, gives the best results by using the fresh samples. In this study, we reached good results by using formalin fixed sections. The layers of the hippocampal formation were differentiated. The pyramidal and granular cells were identified together with their axons and dendrites (Fig. 9, Ref. 22). Full Text (Free, PDF) www.bmj.sk.

A variable origin of the vertebral artery.

This study presents and describes the variation of the vertebral artery arising from the aortic arch as a case report. This variation was found in one of the cadavers at the Institute of Anatomy of Medical Faculty of Comenius University in Bratislava. Anomalous arising was discovered during the student's dissection of thorax and abdomen. Non standard arising of the vertebral artery is compared to the standard arising in the anatomical literature and atlases. The variable arising was confronted to the possible variations of the vertebral artery reported in literature (Fig. 4, Ref. 9). Full Text (Free, PDF) www.bmj.sk.

History, anatomical nomenclature, comparative anatomy and functions of the hippocampal formation.

The complex structures in the cerebral hemispheres is included under one term, the limbic system. Our conception of this system and its special functions rises from the comparative neuroanatomical and neurophysiological studies. The components of the limbic system are the hippocampus, gyrus parahippocampalis, gyrus dentatus, gyrus cinguli, corpus amygdaloideum, nuclei anteriores thalami, hypothalamus and gyrus paraterminalis Because of its unique macroscopic and microscopic structure, the hippocampus is a conspicuous part of the limbic system. During phylogenetic development, the hippocampus developed from a simple cortical plate in amphibians into complex three-dimensional convoluted structure in mammals. In the last few decades, structures of the limbic system were extensively studied. Attention was directed to the physiological functions and pathological changes of the hippocampus. Experimental studies proved that the hippocampus has a very important role in the process of learning and memory. Another important functions of the hippocampus as a part of the limbic system is its role in regulation of sexual and emotional behaviour. The term "hippocampal formation" is defined as the complex of six structures: gyrus dentatus, hippocampus proprius, subiculum proprium, presubiculum, parasubiculum and area entorhinalis In this work we attempt to present a brief review of knowledge about the hippocampus from the point of view of history, anatomical nomenclature, comparative anatomy and functions (Tab. 1, Fig. 2, Ref. 33).

Professor Julius Alexander Ledenyi-Ladziansky--centenary of a personality.

Professor J. A. Ledenyi-Ladziansky, academician, anatomist, researcher, scientist, author, beloved and disliked by others at the same time, a personality in a true sense, was born 100-years ago. (Fig. 3, Ref. 8.)

Andreas Vesalius--the reformer of anatomy.

This paper deals with two main topics. The first part provides data on the life of Andreas Vesalius, a scholar and anatomist of the 16th century, and describes the environment in which he lived and worked. It highlights his personality of a great doctor and teacher and points out the importance of his scientific methods and techniques as opposed to speculative methods that were prevalent in the scientific research in those days. The second part of the paper is devoted to the characteristics and description of his famous and, given the times he lived in, grand work called "De Humani Corporis Fabrica", which opened a new epoch in the history of anatomy. Andreas Vesalius is considered to be the founder of the science of anatomy which is based on observation and experience gained by using scalpel on dead bodies of humans. This is how he proved the then valid statements wrong. This complex view of life and work of Andreas Vesalius is aimed at highlighting the milestone which he represents in this traditional science of anatomy that has been conscientiously developed since the Classical times. (Fig. 4, Ref. 6.)

The determination of the collagen and elastin amount in the human varicose vein by the computer morphometric method.

The results of the works dealing with alterations of the connective tissue in varicose vein wall are not ambiguous, so the exact cause of the vein dilatation has still not been established. We were determining the collagen and elastin amounts in human varicose vein wall in comparison with non-dilated long saphenous vein by the light microscopy and computer morphometric method. We have found the lesser amount of collagen in varicose veins than in non-dilated veins, the amounts of the elastin in both the varicose and non-varicose veins were without the statistical significance.

Detection of ischemic changes in the cytoplasm of neurocytes from rat brain and spinal cord by densitometric measurement of methylene blue binding.

Ischemic changes in neurocytes from brain and spinal cord of rats were studied by densitometric measurement of bound basic stain--methylene blue. Statistically significant differences in integrated optical density (I.O.D.) of cytoplasm near to cell nucleus in brain and spinal cord neurocytes were detected after ischemia. After 10 minutes of ischemia, the average values of I.O.D. decreased to 65% and to 69.9% of I.O.D. values of controls. After 2 hours of ischemia, the average values of I.O.D. in brain cell cytoplasm reached only 43.6% and in the spinal cord cells they fell to 54.5% of control values.

[Morphometric analysis of the spleen]. / Skúsenosti s morfometrickou analýzou sleziny.

Present possibilities of morphometric analysis of the spleen have been studied. We have compared possibilities provided by stereological calculation and by computer image analysators a) Telemet II (Tesla, Piestany) and b) CUE-2 GALAI (Israel). In both latter cases equidensitometric evaluation and image processing methods were used. Stereological calculations are not technically demanding but time consuming. Computer image processing on the base of equidensitometric measurements is more effective that stereological calculations. The difference between used equipments is based on access to appropriate microscopic and computer technique and software equipment.

The morphological picture of implanted foetal rat brain tissue.

The authors studied the morphological picture of implanted foetal brain tissue. Macroscopically, they found that the grafts used for morphological study had taken in every case and that the size of the graft had doubled or trebled. The surface of the implant grew above the level of the recipient's cortex and numerous branching blood vessels were observed in the graft-cortex contact area. In the light microscope, organization of the cells in circular clusters or strips was found in the implant. Large numbers of blood vessels of varying calibre were present in the vicinity of large cell concentrations. Distinct differences between the cytoarchitectonics of the normal tissue of the recipient and the graft tissue were seen. Cells with a normal appearance or an apolar form, whose nucleus contained irregularly scattered chromatin and mosaic-like nucleoli, were observed at ultrastructural level. The nuclear membrane was thrown into multiple folds which invaginated deep into the nuclear matter. The Golgi complex covered a large area. Axodendritic synapses indistinguishable from the control were found in the neuropil. No changes were observed in the walls of the capillaries. The pericapillary zone was characterized by the presence of light astrocyte processes.

Ultrastructural changes in the brain capillaries after hypoxia.

The authors describe ultrastructural changes in and around rat brain capillaries after hypoxia. The experimental animals breathed a mixture of 5% oxygen and 95% nitrogen for two or for three hours; a third group, which spent three hours in this atmosphere, was treated 24 h later. Cytoplasm processes and vesicles were observed on the luminal side in the endothelial cells, while the cytoplasm contained vacuoles and altered mitochondria. The basement membrane of the brain capillaries was uneven and longitudinal clear zones were formed in it. Altered mitochondria were present in the pericytes and astrocytes. The most pronounced changes were found in the astrocyte processes, which were light and hydrated and contained destroyed mitochondria and lamellar bodies resembling myelin. After 24 h, morphological changes still persisted, especially in the astrocyte processes.

The ultrastructural picture of cerebral cortex of rat after hypoxia. I. Findings after inhalation of 5% O2 and 95% N2.

The ultrastructure of some elements in the motor region of the cerebral cortex of the rat were studied after hypoxia. The experimental animals, after receiving intraperitoneal chloral hydrate anaesthesia, were placed in a chamber with a controlled supply of a mixture of 95% N2 and 5% O2. After 2- and 3-hour exposure to hypoxic conditions the animals were processed for electron optic study. Edematous mitochondria pith partial or total destruction of the mitochondrial matrix were observed. Some mitochondria were changed into large vacuolar formations. The granular endoplasmic reticulum of neurocytes was dilated and in the broad dilatation structures of lamellar shape were sporadically found. The Golgi complex contained vacuoles of different sizes and long cisterns. Hydrated astrocytes were visualized in the neuropil and perivascular astrocyte processes displayed edematous changes. In the group of animals exposed to hypoxia for 3 hours but processed only 24 hours after termination of hypoxia the same changes were observed yet their extent was considerably diminished. This finding indicates that changes induced by hypoxia tend to return to normal conditions.