Suitability of electroencephalography in brain death determination: a monocentric, 10-year retrospective, observational investigation of 428 cases

Background We aimed to verify the usefulness of electroencephalographic (EEG) activity recording (that is mandatory according to the Italian law), in addition to two clinical evaluations spaced 6 h, among the procedures of brain death determination (BDD) in adult individuals. Methods The study is a monocentric, retrospective analysis of all BDDs performed in the last 10 years at Policlinico Le Scotte in Siena (Italy). Results Of the 428 cases revised (mean age 67.6 ± 15.03 years; range 24–92 years), 225 were males and 203 females. In total, 212 out of 428 patients (49.5%) were donors. None of the BDD procedures were interrupted due to the reappearance of EEG activity (neither for clinical reasons) at any sampling time, with the exception of one case that was considered a false negative at critical reinspection of the EEG. In 6/428 cases (1.4%), a cardiac arrest occurred during the 6 h between the first and second evaluation, thus missing the opportunity to take organs from these patients because the BDD procedure was not completed. Conclusions Once the initial clinical examination before convening the BDD Commission has ascertained the absence of brainstem reflexes and of spontaneous breathing, and these clinical findings are supported by a flat EEG recording, the repetition of a 30-min EEG twice over a 6 h period seems not to add additional useful information to clinical findings. Current data, if confirmed in other centers and possibly in prospective studies, may help to promote a scientific and bioethical debate in Italy, as well as in other countries where the EEG is still mandatory, for eventually pdating the procedures of BDD. © 2022, The Author(s)

Abnormal Circadian Modification of A\u3b4-Fiber Pathway Excitability in Idiopathic Restless Legs Syndrome

Restless legs syndrome (RLS) is characterized by unpleasant sensations generally localized to legs, associated with an urge to move. A likely pathogenetic mechanism is a central dopaminergic dysfunction. The exact role of pain system is unclear. The purpose of the study was to investigate the nociceptive pathways in idiopathic RLS patients. We enrolled 11 patients (mean age 53.2\u2009\ub1\u200919.7 years; 7 men) suffering from severe, primary RLS. We recorded scalp laser-evoked potentials (LEPs) to stimulation of different sites (hands and feet) and during two different time conditions (daytime and nighttime). Finally, we compared the results with a matched control group of healthy subjects. The A\u3b4 responses obtained from patients did not differ from those recorded from control subjects. However, the N1 and the N2-P2 amplitudes' night/day ratios after foot stimulation were increased in patients, as compared to controls (N1: patients: 133.91\u2009\ub1\u200950.42%; controls: 83.74\u2009\ub1\u200934.45%; p = 0.016; A\u3b4-N2-P2: patients: 119.15\u2009\ub1\u200915.56%; controls: 88.42\u2009\ub1\u200923.41%; p = 0.003). These results suggest that RLS patients present circadian modifications in the pain system, which are not present in healthy controls. Both sensory-discriminative and affective-emotional components of pain experience show parallel changes. This study confirms the structural integrity of A\u3b4 nociceptive system in idiopathic RLS, but it also suggests that RLS patients present circadian modifications in the pain system. These findings could potentially help clinicians and contribute to identify new therapeutic approaches

Migraine, arousal and sleep deprivation: comment on: "sleep quality, arousal and pain thresholds in migraineurs: a blinded controlled polysomnographic study"

We discuss the hypothesis proposed by Engstrom and coworkers that Migraineurs have a relative sleep deprivation, which lowers the pain threshold and predispose to attacks. Previous data indicate that Migraineurs have a reduction of Cyclic Alternating Pattern (CAP), an essential mechanism of NREM sleep regulation which allows to dump the effect of incoming disruptive stimuli, and to protect sleep. The modifications of CAP observed in Migraineurs are similar to those observed in patients with impaired arousal (narcolepsy) and after sleep deprivation. The impairment of this mechanism makes Migraineurs more vulnerable to stimuli triggering attacks during sleep, and represents part of a more general vulnerability to incoming stimuli

Caratterizzazione meccanica del composito Ti6Al4V/SiCf dopo prolungata esposizione ad alta temperatura

Il composito con matrice Ti6Al4V rinforzato con fibre lunghe di SiC (tipo SCS-6) è un materiale di grande interesse per applicazioni nei motori aeronautici. Non esistendo dati specifici di letteratura relativi al comportamento meccanico del composito dopo esposizione ad alta temperatura, simulante quella di esercizio, si sono eseguite prove meccaniche (trazione, microdurezza e indentazione strumentata con punta cilindrica a testa piatta-FIMEC) per studiare la presenza di un eventuale degrado rispetto al materiale non trattato. Preliminarmente, per valutare eventuali effetti dell’atmosfera durante l’esposizione in temperatura, sono state eseguite prove FIMEC su campioni non protetti trattati per 1 ora a 100, 200, 300, 400, 500 e 600 °C in vuoto, argon e aria. I risultati mostrano chiaramente un peggioramento del comportamento meccanico rispetto al materiale non trattato. Tale degrado è di entità maggiore nel caso del trattamento in aria, tuttavia anche negli altri due casi la presenza residua di ossigeno comporta danni alla struttura del composito e ne compromette le caratteristiche meccaniche. Pertanto il materiale potrà esser posto in esercizio solo proteggendo preventivamente le fibre e l’interfaccia fibra-matrice. Tutte le prove successive sono state eseguite dopo aver ricoperto per spruzzatura i provini con nitruro di boro. I trattamenti termici sono stati eseguiti in vuoto alle temperature di 400°C e 600°C con tempi di permanenza di 100, 500 e 1000 ore. Una serie di campioni è stata esposta per 100 e 1000 ore a 600 °C in atmosfera di gas inerte con tensione applicata di 15 MPa. Le prove di trazione su questi provini sono state eseguite a temperatura ambiente e a 600 °C. La modesta variazione delle proprietà meccaniche rispetto a quelle iniziali, anche nelle condizioni più severe di trattamento termico, indica che non c’è degrado significativo della struttura, in particolare dell’interfaccia fibra-matrice. Questo è stato confermato anche da osservazioni SEM delle superfici di frattura. Il lavoro dimostra che il composito Ti6Al4V/SiCf , una volta protetto con nitruro di boro, offre ottime garanzie per operare anche per tempi prolungati alle temperature di esercizio tipiche dei compressori dei motori aeronautici

Expectation to feel more pain disrupts the habituation of laser-pain rating and laser-evoked potential amplitudes

Increased pain perception due to the expectation to feel more pain is called nocebo effect. The present study aimed at investigating whether: (1) the mere expectation to feel more pain after the administration of an inert drug can affect the laser-pain rating and the laser-evoked potential (LEP) amplitude, and (2) the learning potentiates the nocebo effect. Eighteen healthy volunteers were told that an inert cream, applied on the right hand, would increase the laser pain and LEP amplitude to right hand stimulation. They were randomly assigned to either "verbal session" or "conditioning session". In the "verbal session", LEPs to both right and left hand stimulation were recorded at the same intensity before (baseline) and after cream application. In the "conditioning session", after an initial cream application the laser stimulus intensity was increased surreptitiously to make the subjects believe that the treatment really increased the pain sensation. Then, the cream was reapplied, and LEPs were recorded at the same stimulus intensity as at the baseline. It was found that the verbal suggestion to feel more pain disrupted the physiological habituation of the laser-pain rating and LEP amplitude to treated (right) hand stimulation. Unlike previously demonstrated for the placebo effect, the learning did not potentiate the nocebo effect

Autonomic Nervous System Modifications During Wakefulness and Sleep in a Cohort of Patients with Acute Ischemic Stroke

Goal: The aims of our study were to investigate autonomic modifications in wakefulness and sleep in a cohort of patients with acute ischemic stroke and to evaluate whereas these modifications were dependent by sleep stage and stroke lateralization. Materials and Methods: We prospectively enrolled 42 patients (22 men and 20 women, mean age: 69.8 \ub1 11.3; range: 32-92 years) with acute ischemic stroke. All participants underwent a full-night polysomnography. As index of autonomic nervous system we used Heart Rate Variability (HRV), analyzed in wakefulness and during different sleep stages. First, we compared our cohort with a control group of 42 healthy subjects, matched for age and sex. Subsequently, we divided our cohort in 2 subgroups according stroke lateralization (21 right, 21 left) and compared with control population. Findings: We observed significant modifications of HRV parameters mainly for the right lesions. In particular, we observed a prevalent parasympathetic tone during the wake (low frequency/high frequency [LF/HF]: right: 2.99 \ub1 8.91; controls: 3.88 \ub1 3.42; P < .01) and during REM (LF/HF right: 0.03 \ub1 1.58; controls: 2.92 \ub1 3.97; P < .01) accompanied by a significant reduction of sympathetic tone during REM (LF right: 23.85 \ub1 44.42 n.u.; controls: 51.13 \ub1 32.25 n.u.; P < .01), and by a reduction of parasympathetic tone during N3 (HF right: 28.09 \ub1 37.67 n.u.; controls: 43.08 \ub1 68.39 n.u.; P < .01). Conclusions: Our study indicates that autonomic dysfunctions in acute ischemic stroke are prevalent in right-side lesions and strictly dependent by sleep-wake stage

What causes sleep-disordered breathing in Chiari I malformation? Comment on: "MRI findings and sleep apnea in children with Chiari I malformation"

No abstract availabl

Low-Frequency rTMS of the Primary Motor Area Does Not Modify the Response of the Cerebral Cortex to Phasic Nociceptive Stimuli

Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive technique of cortical stimulation. Although the exact mechanism of action is not clearly understood, it has been postulated that rTMS action on pain depends most on stimulation sites and stimulation parameters. Most studies concern high-frequency rTMS of the primary motor cortex (M1). High-frequency rTMS over motor cortex seems to induce an analgesic effect while contrasting results were reported after low-frequency rTMS. The aim of the current study was to investigate the effects of 1 Hz rTMS stimulation over the left primary motor cortex on subjective laser pain rating and laser evoked potential (LEP) amplitudes in healthy subjects. Subjects underwent two different sessions (real and sham rTMS) according to a cross-sectional design. In each session, LEPs and laser-pain rating to stimulation of both right and left hand dorsum were collected before 1 Hz rTMS over the left M1 area (baseline), which lasted 20 min. Then, LEPs and laser-pain rating were measured immediately after rTMS (T0), after 20 min from T0 (T0+20), and after 40 min from T0 (T0+40). We could not find any modification of both laser-pain rating and LEP parameters (latencies and amplitudes) following 1 Hz rTMS. Therefore, our results show that the low-frequency rTMS of the M1 area does not change the response of the cerebral cortex to pain

Periodic sighs

A 2 year-old girl, affected by achondroplasia, underwent an overnight, laboratory-based video-polysomnographic study aimed to study the respiratory pattern in sleep. The parents reported repeated episodes of \u2018respiratory pauses\u2019 during sleep. No parasomnia, rhythmic movements during sleep, snoring or noisy breathing was reported; otorhynolaringoiatric evaluation was unremarkable, body mass index was 21.5, no diurnal symptoms of sleepiness or other behavioral modifications were present. Neurological examination was normal, and no evidence of cardiac or respiratory pathologies were present. Sleep EEG was normal, and NREM and REM sleep stages were recorded. During all NREM sleep stages, PSG recording showed recurrent sighs, characterized by increase of the airflow signal. Sighs repeated periodically, were associated in most cases with an EEG arousal, and were followed by a short respiratory pause (a brief apnea of central type, not associated with EEG arousal and not followed by modifications in peripheral haemoglobin desaturations). Video recording confirmed that PSG sighs consisted in a deep breath, followed by a short lasting (2-4 seconds) respiratory pause

Focal Mechanical Vibration Does not Change Laser-Pain Perception and Laser-Evoked Potentials: A Pilot Study

Background: Nonpainful tactile and electrical stimulation of the large myelinated fibers reduces spontaneous pain and the amplitude of laser-evoked potentials (LEPs), which represent the most reliable technique to assess the nociceptive pathway function. Focal mechanical vibration stimulates the A\u3b2 afferents selectively; thus, it is conceivable its action on nociceptive pathways. Aim: The aim of this study was to investigate the effect of vibratory stimuli, activating either both muscle and skin receptors or cutaneous afferents only on the LEPs and subjective laser-pain rating. Methods: Ten healthy volunteers were studied. The subjects were evaluated in two different sessions to test muscle and skin receptors or cutaneous afferents only. In each session, LEPs were recorded to stimulation of the dorsal hand skin in radial and ulnar territory bilaterally, while the vibratory stimulus was delivered on the radial territory of the right forearm. Results: The results showed a substantial stability of the potential N1 and N2/P2 after the two protocols, with a declining trend from the initial to the last test of the same session, probably due to habituation. Accordingly, the laser-pain perception did not change during the experimental setting. Conclusions: We conclude that a vibratory stimulus is ineffective in reducing the laser-evoked potentials and laser-pain perception. \ua9 2016 World Institute of Pain