Endoscopic discectomy of the herniated intervertebral disc and changes in quality-of-life EQ-5D-5L analysis

Herniated lumbar discs are a common cause of low back pain, which can negatively impact the quality of life of working-age individuals. This study aimed to evaluate changes in the quality of life in patients with sciatica who underwent endoscopic discectomy, a minimally invasive surgical procedure. The study (ClinicalTrials.gov NCT02742311) included 470 patients who underwent transforaminal, interlaminar, or translaminar endoscopic discectomy. Quality of life and pain perception were evaluated by comparing statistically weighted values of EQ-5D-5L, EQ-VAS, Oswestry disability index, and numerical pain scales for lower limb and back pain before and 12 months after the endoscopic procedure. After the procedure, there was a significant improvement in the reduction of back and lower limb pain, as well as in all monitored questionnaires (P < .001), which persisted 12 months after the endoscopy. All evaluated dimensions of the EQ-5D-5L questionnaire indicated a significant improvement in the assessed quality of life (P < .001). The study showed that percutaneous endoscopic lumbar discectomy is an effective pain-treating intervention that can improve the quality of life. There was no observed difference in the percentage of complications or re-herniations when comparing the transforaminal and interlaminar, approaches.

Pain and the emotional brain: pain-related cortical processes are better reflected by affective evaluation than by cognitive evaluation

The experience of pain has been dissociated into two interwoven aspects: a sensory-discriminative aspect and an affective-motivational aspect. We aimed to explore which of the pain descriptors is more deeply rooted in the human brain. Participants were asked to evaluate applied cold pain. The majority of the trials showed distinct ratings: some were rated higher for unpleasantness and others for intensity. We compared the relationship between functional data recorded from 7 T MRI with unpleasantness and intensity ratings and revealed a stronger relationship between cortical data and unpleasantness ratings. The present study underlines the importance of the emotional-affective aspects of pain-related cortical processes in the brain. The findings corroborate previous studies showing a higher sensitivity to pain unpleasantness compared to ratings of pain intensity. For the processing of pain in healthy subjects, this effect may reflect the more direct and intuitive evaluation of emotional aspects of the pain system, which is to prevent harm and to preserve the physical integrity of the body.

Interindividual Variability and Individual Stability of Pain- and Touch-Related Neuronal Gamma Oscillations

Background. Brief painful laser and innocuous tactile stimuli have been associated with an increase of neuronal oscillations in the gamma range. However, it is indicated that event-related gamma oscillations may be highly variable across individuals, but no study has systematically studied interindividual variability and individual stability of induced gamma synchronisation. Here, we addressed this question using two datasets. Methods. The present study includes two EEG datasets. The first dataset contains two repeated sessions of tactile and painful stimulation from 22 participants. The second dataset contains a single session of painful stimulation from 48 participants. Results. In the first dataset, we observed gamma responses in the majority of the included participants. We found a broad interindividual variety of gamma magnitudes, time-frequency response patterns, and scalp topographies. Some participants showed a gamma response with individually unique time-frequency patterns, others did not exhibit any gamma response. This was reproducible and therefore stable; subjects with a large gamma magnitude in the first session showed a large gamma magnitude and a similar response pattern in the follow-up session. The second dataset confirmed the large between-subject variability, but only a fraction of the included participants exhibited laser-induced gamma synchronisation. Conclusions. Our results indicate that current EEG measures do not reflect the complex reality of the diverse individual response patterns to brief pain and touch experiences. The present findings question whether a similar phenomenon would be observed in other neuroscience domains. Group results may be replicable, but could be driven by a subgroup of the sample.

Intrinsic Network Activity Reflects the Fluctuating Experience of Tonic Pain

Although we know sensation is continuous, research on long-lasting and continuously changing stimuli is scarce and the dynamic nature of ongoing cortical processing is largely neglected. In a longitudinal study, 38 participants across four sessions were asked to continuously rate the intensity of an applied tonic heat pain for 20 min. Using group-independent component analysis and dual regression, we extracted the subjects' time courses of intrinsic network activity. The relationship between the dynamic fluctuation of network activity with the varying time courses of three pain processing entities was computed: pain intensity, the direction of pain intensity changes, and temperature. We were able to dissociate the spatio-temporal patterns of objective (temperature) and subjective (pain intensity/changes of pain intensity) aspects of pain processing in the human brain. We found two somatosensory networks with distinct functions: one network that encodes the small fluctuations in temperature and consists mainly of bilateral primary somatosensory cortex (SI), and a second right-lateralized network that encodes the intensity of the subjective experience of pain consisting of SI, secondary somatosensory cortex, the posterior cingulate cortex, and the thalamus. We revealed the somatosensory dynamics that build up toward a current subjective percept of pain. The timing suggests a cascade of subsequent processing steps toward the current pain percept.

Patients with chronic pain exhibit individually unique cortical signatures of pain encoding

Chronic pain is characterised by an ongoing and fluctuating intensity over time. Here, we investigated how the trajectory of the patients' endogenous pain is encoded in the brain. In repeated functional MRI (fMRI) sessions, 20 patients with chronic back pain and 20 patients with chronic migraine were asked to continuously rate the intensity of their endogenous pain. Linear mixed effects models were used to disentangle cortical processes related to pain intensity and to pain intensity changes. At group level, we found that the intensity of pain in patients with chronic back pain is encoded in the anterior insular cortex, the frontal operculum, and the pons; the change of pain in chronic back pain and chronic migraine patients is mainly encoded in the anterior insular cortex. At the individual level, we identified a more complex picture where each patient exhibited their own signature of endogenous pain encoding. The diversity of the individual cortical signatures of chronic pain encoding results bridge between clinical observations and neuroimaging; they add to the understanding of chronic pain as a complex and multifaceted disease.

Migraine attacks as a result of hypothalamic loss of control

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Hypothalamo-limbic connectivity reflects the cyclic nature of migraine.

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Hypothalamo-limbic connectivity is largest just before the attack.

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Hypothalamo-limbic connectivity is collapsing during the attack.

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Limbic perfusion is increasing and has a maximum during the attack.

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The disrupted connectivity allows high limbic perfusion, resulting in migraine attack.

Migraine is a complex neurological disorder affecting approximately 12% of the population. The pathophysiology is not yet fully understood, however the clinical features of the disease, such as the cyclic behaviour of attacks and vegetative symptoms, suggest a prominent role of the hypothalamus. Previous research has observed neuronal alterations at different time points during the migraine interval, specifically just before the headache is initiated. We therefore aimed to assess the trajectory of migraineurs’ brain activity over an entire migraine cycle.

Using functional magnetic resonance imaging (fMRI) with pseudo-continuous arterial spin labelling (ASL), we designed a longitudinal intra-individual study to detect the rhythmicity of (1) the cerebral perfusion and (2) the hypothalamic connectivity over an entire migraine cycle. Twelve episodic migraine patients were examined in 82 sessions during spontaneous headache attacks with follow-up recordings towards the next attack.

We detected cyclic changes of brain perfusion in the limbic circuit (insula and nucleus accumbens), with the highest perfusion during the headache attack. In addition, we found an increase of hypothalamic connectivity to the limbic system over the interictal interval towards the attack, then collapsing during the headache phase.

The present data provide strong evidence for the predominant role of the hypothalamus in generating migraine attacks. Due to a genetically-determined cortical hyperexcitability, migraineurs are most likely characterised by an increased susceptibility of limbic neurons to the known migraine trigger. The hypothalamus as a metronome of internal processes is suggested to control these limbic circuits: migraine attacks may occur as a result of the hypothalamus losing control over the limbic system. Repetitive psychosocial stress, one of the leading trigger factors reported by patients, might make the limbic system even more vulnerable and lead to a premature triggering of a migraine attack. Potential therapeutic interventions are therefore suggested to strengthen limbic circuits with dedicated medication or psychological approaches.

EQ-5D-5L questionnaire as suitable assessment of quality of life after epiduroscopy : Multicenter randomized double-blind pilot study

BACKGROUND

Epiduroscopy is a well-established diagnostic and to certain level therapeutic tool in complex situations, where conventional methods such as magnetic resonance imaging (MRI) lack power or resolution to detect pathological changes. Such a situation is primarily failed back surgery syndrome (FBSS) but also radicular pain without surgery. The aim of this study was to determine the effectiveness of epiduroscopic treatment in patients with FBSS.

METHODS

A total of 79 patients with FBSS were randomized into 2 groups. The first group underwent epiduroscopy and received mechanical lysis of adhesions only, the second group received also medication into the epidural space (methylprednisolone and hyaluronidase). Patients were subsequently followed for 12 months, with evaluation also after 6 months post-epiduroscopy. Patients were checked in terms of mobility, self-care, usual activities, pain/discomfort and anxiety/depression as defined in the 5‑dimensional EQ-5D-5L questionnaire and to asses suitability of this questionnaire in chronic pain states. Data were collected using EQ-5D-5L questionnaire and also quality of life (QoL) questionnaire.

RESULTS

In the terms of ability to walk (dimension mobility) and also ability to do housework, study or leisure activities (dimension usual activity) patients improved in both groups after 6 and 12 months after epiduroscopy. In pain dimension there was improvement mainly after 6 months which correlated also with self-care dimension and quality of life self-assessment. Results in anxiety/depression dimension were mixed.

CONCLUSION

Epiduroscopy appears to be a beneficial procedure for both patient groups, especially after 6 months, with some benefit remaining after 12 months. The EQ-5D-5L questionnaire seems to be a suitable and comprehensive way to assess patient health in chronic pain states.

Prefrontal Gamma Oscillations Encode Tonic Pain in Humans

Under physiological conditions, momentary pain serves vital protective functions. Ongoing pain in chronic pain states, on the other hand, is a pathological condition that causes widespread suffering and whose treatment remains unsatisfactory. The brain mechanisms of ongoing pain are largely unknown. In this study, we applied tonic painful heat stimuli of varying degree to healthy human subjects, obtained continuous pain ratings, and recorded electroencephalograms to relate ongoing pain to brain activity. Our results reveal that the subjective perception of tonic pain is selectively encoded by gamma oscillations in the medial prefrontal cortex. We further observed that the encoding of subjective pain intensity experienced by the participants differs fundamentally from that of objective stimulus intensity and from that of brief pain stimuli. These observations point to a role for gamma oscillations in the medial prefrontal cortex in ongoing, tonic pain and thereby extend current concepts of the brain mechanisms of pain to the clinically relevant state of ongoing pain. Furthermore, our approach might help to identify a brain marker of ongoing pain, which may prove useful for the diagnosis and therapy of chronic pain.

On the Exact Two-Sided Tolerance Intervals for Univariate Normal Distribution and Linear Regression

Statistical tolerance intervals are another tool for making statistical inference on anunknown population. The tolerance interval is an interval estimator based on the resultsof a calibration experiment, which can be asserted with stated confidence level 1 ? ,for example 0.95, to contain at least a specified proportion 1 ? , for example 0.99, ofthe items in the population under consideration. Typically, the limits of the toleranceintervals functionally depend on the tolerance factors. In contrast to other statisticalintervals commonly used for statistical inference, the tolerance intervals are used relativelyrarely. One reason is that the theoretical concept and computational complexity of thetolerance intervals is significantly more difficult than that of the standard confidence andprediction intervals.In this paper we present a brief overview of the theoretical background and approachesfor computing the tolerance factors based on samples from one or several univariate normal(Gaussian) populations, as well as the tolerance factors for the non-simultaneousand simultaneous two-sided tolerance intervals for univariate linear regression. Such toleranceintervals are well motivated by their applicability in the multiple-use calibrationproblem and in construction of the calibration confidence intervals. For illustration, wepresent examples of computing selected tolerance factors by the implemented algorithmin MATLAB.

γ Oscillations are involved in the sensorimotor transformation of pain

Pain signals threat and initiates motor responses to avoid harm. The transformation of pain into a motor response is thus an essential part of pain. Here, we investigated the neural mechanisms subserving the sensorimotor transformation of pain at the cortical level by using electroencephalography. In a simple reaction time experiment, brief painful stimuli were delivered to the left hand of healthy human subjects who responded with button presses of the right hand. The results show that the simple reaction time task was associated with neuronal responses at delta/theta, alpha/beta, and gamma frequencies. The analysis of the relationship between neuronal activity and response speed revealed that gamma oscillations, which were temporally coupled to the painful stimuli, but not temporally coupled to the motor response, predicted reaction times. Lateralization of gamma oscillations indicates that they originate from motor areas rather than from sensory areas. We conclude that gamma oscillations are involved in the sensorimotor transformation of pain whose efficiency they reflect. We hypothesize that the relationship between stimulus-locked gamma oscillations and reaction times reflects a direct thalamo-motor route of nociceptive information that is central to the biological function of pain.

Radiosensitivity of peripheral blood lymphocytes from healthy donors and cervical cancer patients; the correspondence of in vitro data with the clinical outcome

The reliability of a particular in vitro parameter as potential prognostic biomarker of individual radiosensitivity is still discussed. Therefore, several in vitro radiation-induced cellular endpoints including initial, oxidative and residual DNA damage and the rate of DNA repair were assessed in peripheral blood lymphocytes (PBL) from healthy donors and patients with carcinoma of the cervix using the alkaline single cell gel electrophoresis (the comet assay). PBL from cancer patients were analyzed three times during the course of therapy, prior, in the middle (25-27 Gy) and after the radiotherapy. Interindividual differences in radiation-induced DNA damage and in the kinetics of strand break rejoining were determined within both groups. Significantly higher level of mean background and oxidative DNA damage was estimated in the cancer patient cohort than in the healthy subject group; however similar mean values of the initial DNA damage and the rate of DNA repair kinetics were found in both groups. No adaptive response was determined in PBL from cancer patients due to radiotherapy. The acute radiation toxicity and the clinical outcome were scored according to the criteria as proposed by the National Cancer Institute. A substantial delay in DNA strand break rejoining was determined in cancer patients suffering from adverse side effects (G2+) in comparison to persons with no or very mild radiation toxicity (G0-G1) (p<0.05). The recurrence of disease has been associated with a lower initial DNA damage and slope value of dose-response effect, and increased rate of DNA repair. Results from this pilot study suggest that the residual DNA damage level might be a promising prognostic biomarker of acute radiation morbidity; however, further study is necessary to validate this finding.

Significance of amino acid substitution variants of DNA repair genes in radiosusceptibility of cervical cancer patients; a pilot study

The present pilot study was designed to elucidate the functional significance of amino acid substitution variants of DNA repair genes. Using the peripheral blood lymphocytes (PBLs) from healthy donors and cervical cancer patients, the contribution of four non-synonymous single nucleotide polymorphisms (SNPs) in three base excision repair genes (BER), XRCC1 (Arg194Trp and Arg399Gln), hOGG1 (Ser326Cys), and APE1 (Asp148Glu), to the susceptibility to ionizing radiation were evaluated. The level of initial, oxidative and residual DNA damage produced by 2 Gy was measured by the alkaline single cell gel electrophoresis (the comet assay), and the SNPs were determined by PCR-restriction fragment length polymorphism (RFLP) assay. No significant differences in the allele frequencies between cancer patients and controls for any of these four SNPs were detected. Although the initial DNA damage levels were approximately similar, significantly higher level of Fpg-sensitive sites were found in patients compared with controls (p<0.001) irrespective of genotype distribution. A trend towards increased values of EndoIII-sensitive sites was determined in PBLs from cancer patients compared with healthy women, mainly carriers of the XRCC1 and OGG1 variant alleles; however, the mean value of EndoIII-sensitive sites does not reach any significance. A substantial delay in DNA strand-break rejoining was ascertained in patients who carried APE1 Glu variant allele in comparison with healthy donors 15 and 60 minutes after irradiation (p< 0.05 and p< 0.01, respectively). In contrast, slightly higher but statistically significant level of residual DNA damage was estimated in controls (APE1Asp/Asp) compared with patients. An association between single nucleotide polymorphism (SNP) of two DNA repair genes functioning in the same biochemical pathway and susceptibility to radiation was found. In the combined genotype APE1/XRCC1 and APE1/hOGG1, a decreased level of residual DNA damage was detected in carriers of wild type APE1 genotype. In addition, a possible modulating effect of hOGG1 gene on the kinetics of strand-break rejoining was estimated. The lowest residual DNA damage level was determined in subjects with the combined APE1(Asp/Asp)/hOGG1(Ser/Cys+Cys/Cys) genotypes. Based on these preliminary data we suppose that a combination of several amino acid substitution variants of DNA repair genes involved in the same repair pathway rather than one low-penetrance SNP in a single gene may contribute to DNA repair outcomes. Larger study with more subjects is needed to verify these findings.