Loss of regulation of the autonomic nervous system is found in many diseases from the age of 50 to 60 yr and even more so in older patients. The imbalance is usually manifested by an increase in sympathetic tone, long considered to be the most deleterious element in terms of cardiac rhythmic risk, but also by a reduction in the effectiveness of short-term regulation of the baroreflex arc (partial loss of parasympathetic control). Techniques for analysing this autonomic disorder by analysing heart rate regulation are widely available in outpatient clinics and provide interesting indicators of cardiovascular and cerebrovascular risk. Deceleration capacity of cardiac autonomic control has been identified for its prognostic role in high-risk patients and in the general population. Further research is indicated to assess the value of this marker in anaesthetic risk management by targeting procedures with greater risk of intraoperative and postoperative autonomic dysfunction.

INTRODUCTION:Anterolateral cordotomy (AL-C) is a long-established treatment for alleviating intractable cancer pain. However, AL-C has progressively fallen into desuetude, leading to the risk of a definitive loss of expertise within neurosurgical teams. Our objective was therefore to provide an update on percutaneous and open AL-C, with special emphasis on contemporary operative technique. MATERIAL AND METHODS:Patient selection, indications, outcomes and up-to-date operative technique are reviewed through illustrative cases, including intraoperative photographs and video. RESULTS:Main indications are represented by unilateral, nociceptive pain refractory to best pharmacological treatment in patients with limited life expectancy. Percutaneous AL-C is performed under cooperative sedation at C1-C2 level. CT myelography guidance and intraoperative electrophysiology allow accurate targeting of the spinothalamic tract (STT). Thermocoagulation is performed at 80 °C for 60 s during a Mingazzini maneuver, in order to promptly detect the potential onset of a motor weakness. Open AL-C is performed under general anesthesia at T2-T3 level. The dentate ligament is suspended to gently rotate the spinal cord and expose the anterolateral column. Section of the STT is made with a micro scalpel blade at a depth of 4-5 mm, from the dentate ligament to the emergence of ventral rootlets. Success rate after AL-C is high and allows a marked reduction in antalgic drugs intake. Main limitations include failure in achieving long-standing pain relief and the new occurrence of spontaneous, mirror pain. CONCLUSION:AL-C is a safe and effective option for the management of opioid-resistant cancer pain, which should be part of the neurosurgeon's armamentarium.

Introduction: The aim of this study was to assess the capability of the Unruptured Intracranial Aneurysm Treatment Score (UIATS) to discriminate unruptured intracranial aneurysms (UIAs) at high risk for subarachnoid hemorrhage (aSAH). Material and method: During the period from January 2012 to December 2022, we included all consecutive adult patients admitted to our institution for an aSAH caused by the rupture of a saccular IA. The patient-related, aneurysm-related and treatment-related risk factors considered by UIATS were retrieved from medical records. After UIATS calculation for all ruptured IAs in the cohort, patients were categorized as "true positives (TP)" if UIATS would have (appropriately) oriented the management toward treatment, whereas patients for whom the UIATS would have (inappropriately) recommended observation were categorized as "false negatives (FN)". Patients for whom UIATS was inconclusive were categorized as "undetermined (UND)". Sensitivity of the UIATS (Se (UIATS)) was calculated by using the following formula: TP/(TP + FN). Results: A total of 346 patients (253 women, 73%; mean age = 56 +/- 1.45 years) were incorporated into the final analysis. There were 140 T P (40%), 79 F N (23%) and 127 UND (37%), leading to a Se (UIATS) of 63.9% (CI 58.3-69.5). Cumulatively, the UIATS failed to provide an appropriate recommendation in 60% of the entire cohort. Conclusion: By retrospectively applying the UIATS in a cohort of ruptured IAs, our study emphasizes how vulnerable the UIATS can be. Even if the UIATS suggests conservative management, clinicians should inform patients that there is still a small risk of rupture.

Background: Bradycardia and dysautonomia observed during SARS-Cov2 infection suggests involvement of the autonomic nervous system (ANS). Limited data exists on ANS dysregulation and its association with outcomes in patients with acute respiratory distress syndrome (ARDS) related to COVID-19 (C-ARDS) or other etiologies (NCObjectives: We aimed to explore sympathovagal balance, assessed by heart rate variability (HRV), and its clinical prognostic value in C-ARDS compared with NC-ARDS. Methods: A single-center, prospective case-control study was conducted. Consecutive patients meeting ARDS criteria between 2020 and 2022 were included. HRV was assessed using 1-hour electrographic tracing during a stable, daytime period. Results: Twenty-four patients with C-ARDS and 19 with NC-ARDS were included. Age, sex and ARDS severity were similar between groups. The median heart rate was markedly lower in the C-ARDS group than in the NCARDS group (60 [53-72] versus 101 [91-112] bpm, p<.001). Most of HRV parameters were significantly increased in patients with C-ARDS. HRV correlated with heart rate only in patients with C-ARDS. A positive correlation was found between the low-to high-frequency ratio (LF/HF) and length of intensive care unit stay (r = 0.576, p<.001). Conclusion: This study confirmed that C-ARDS was associated with marked bradycardia and severe ANS impairment, suggesting a sympathovagal imbalance with vagal overtone. Poor outcomes appeared to be more related to sympathetic rather than parasympathetic hyperactivation.

OBJECTIVE:The adequate assessment of pain in the emergency department (ED) can be challenging. Two dynamic pupillary measures used in conscious subjects after a surgical procedure were previously shown to correlate to the magnitude of ongoing pain. The objective of this study was to test the ability of dynamic measures derived from pupillometry to evaluate pain intensity in conscious adult patients admitted to the ED.METHODS:This prospective, interventional, single-centre study was performed between August 2021 and January 2022 (NCT05019898). An assessment of self-reported pain intensity was performed on ED admission by the triage nurse using a numeric rating scale (NRS). This was followed by two dynamic measures derived from pupillometry that were previously correlated with pain perception: the pupillary unrest under ambient light (PUAL) and the pupillary light reflex (PLR).RESULTS:Among the 313 analysed patients, the median age was 41 years, and 52% were women. No correlation was found between self-reported pain ratings and PUAL (r = 0.007) or PLR (baseline diameter r = -0.048; decrease r = 0.024; latency r = 0.019; slope = -0.051). Similarly, the pupillometry measures could not discriminate patients with moderate to severe pain (defined as NRS ≥4).CONCLUSIONS:Pupillometry does not appear to be an effective tool to evaluate pain in the ED environment. Indeed, too many factors influencing the sympathetic system-and thus the dynamic pupillary measures-are not controllable in the ED.SIGNIFICANCE:Pupillometry does not appear to be an effective tool to evaluate pain in the ED environment. There are several possible explanations for these negative results. The factors influencing the sympathetic system-and thus the PD fluctuations-are controllable in the postoperative period but not in the ED (e.g. full bladder, hypothermia). In addition, numerous psychological phenomena can impact pupillometry measurements such as emotional reactions or cognitive tasks. These phenomena are particularly difficult to control in the ED environment.

STUDY DESIGN:Retrospective Cohort. OBJECTIVES:The objective of this study was to analyze postoperative complications in different mFI-11 groups after surgery for odontoid fractures in a geriatric population. METHODS:A single center retrospective review of odontoid fractures surgery (between 2013 and 2022) in patients aged 65 years and older was conducted. The primary outcome was the occurrence of a major complication (Calvien-Dindo ≥4) within 30 days post-surgery. The secondary outcome was the occurrence of a major complication within 3 months after surgery, and death within 1-month post-surgery. Survival curve, multi-variate analysis was performed and adjusted receiver operating characteristic curves were generated. RESULTS:There were 92 patients included in this study, with a mean age of 80.5 years. Serious complication occurred for 16 patients (17%) during hospitalization. Multivariate analysis demonstrated an mFI 11 >.27 was strongly and independently associated with serious complications within 1-month post-surgery (OR = 16.7, 95% CI = 4.50-83), as well as serious complications within 3 months post-surgery (OR = 11.8, 95% CI = 3.48-49.1) and death within 1 month post-surgery (OR = 11.7; 95% CI = 3.02-60.4). The Receiver Operator Characteristics (ROC) curves for the three models all have an Area Under the Curve (AUC) value greater than 0.7. CONCLUSIONS:The mFI-11 is a straightforward and validated tool that can be used during the preoperative period to identify the patient's level of frailty and assess their risk of postoperative complications. Patients with mFI-11 ≥.27 are at greater risk of serious complications within 1 and 3 months' post-surgery and death within 1 month post-surgery.

Introduction: ICU patients with SARS-CoV-2-related pneumonia are at risk to develop a central dysautonomia which can contribute to mortality and respiratory failure. The pupillary size and its reactivity to light are controlled by the autonomic nervous system. Pupillometry parameters (PP) allow to predict outcomes in various acute brain injuries. We aim at assessing the most predictive PP of in-hospital mortality and the need for invasive mechanical ventilation (IV). Material and methods: We led a prospective, two centers, observational study. We recruited adult patients admitted to ICU for a severe SARS-CoV-2 related pneumonia between April and August 2020. The pupillometry was performed at admission including the measurement of baseline pupillary diameter (PD), PD variations (PDV), pupillary constriction velocity (PCV) and latency (PDL). Results: Fifty patients, 90 % males, aged 66 (60-70) years were included. Seven (14 %) patients died in hospital. The baseline PD (4.1 mm [3.5; 4.8] vs 2.6 mm [2.4; 4.0], P = 0.009), PDV (33 % [27; 39] vs 25 % [15; 36], P = 0.03) and PCV (3.5 mm.s(-1) [2.8; 4.4] vs 2.0 mm.s(-1) [1.9; 3.8], P = 0.02) were significantly lower in patients who will die. A PD value <2.75 mm was the most predictive parameter of in-hospital mortality, with an AUC = 0.81, CI 95 % [0.63; 0.99]. Twenty-four (48 %) patients required IV. PD and PDV were significantly lower in patients who were intubated (3.5 mm [2.8; 4.4] vs 4.2 mm [3.9; 5.2], P = 0.03; 28 % [25; 36 %] vs 35 % [32; 40], P = 0.049, respectively). Conclusions: A reduced baseline PD is associated with bad outcomes in COVID-19 patients admitted in ICU. It is likely to reflect a brainstem autonomic dysfunction.

La fragilité est un syndrome multidimensionnel caractérisé par une diminution des réserves fonctionnelles physiques, physiologiques et psychosociales qui augmente la vulnérabilité et diminue la résistance au stress. Dans la population générale, la prévalence de la fragilité augmente exponentiellement avec l’âge. À 65 ans, elle est<10 %, alors qu’au-delà de 85 ans elle est diversement rapportée et peut excéder 50 %. Elle est plus élevée à âge équivalent chez les patients chirurgicaux. La présence d’une fragilité augmente le risque de morbidité majeure, mortalité, durée de séjour, réhospitalisation et dépendance fonctionnelle à long terme, quel que soit le type de chirurgie. L’échelle de fragilité clinique est un outil permettant son dépistage en consultation d’anesthésie. Les patients dépistés et pris en charge pour des chirurgies à haut risque de complications seront au mieux adressés à une équipe gériatrique pour une évaluation standardisée et la mise en place d’une stratégie d’optimisation périopératoire individualisée, multidisciplinaire et multimodale. En pré-opératoire, gestion des comorbidités et de la polymédication, des conduites addictives, de l’anémie, amélioration des conditions sociales de vie, préhabilitation incluant activité physique, support nutritionnel et neuropsychologique seront proposées. Monitorage neurophysiologique de la profondeur de l’anesthésie, titration du remplissage vasculaire, prévention et traitement de l’hypotension, ventilation protectrice, analgésie locorégionale, prévention de l’hypothermie et stratégie transfusionnelle restrictive seront mis en œuvre pendant l’intervention ainsi que les autres mesures de la réhabilitation accélérée après chirurgie. À défaut d’une prise en charge dans une unité dédiée de chirurgie gériatrique, un co-management postopératoire avec une équipe gériatrique complète est souhaitable.

IntroductionMechanisms of postoperative sleep architecture disturbances and sleep-disordered breathing are uncertain. The authors hypothesised that patients undergoing surgery under regional anaesthesia without opioids used for postoperative analgesia would experience lesser changes in these parameters than patients operated under general anaesthesia with per- and postoperative opioids.Patients and methodsAfter ethical approval and informed consent, patients undergoing total hip replacement were included in a prospective, randomised trial comparing 3 groups of patients: (1) S-LPB group receiving spinal anaesthesia and postoperative analgesia by lumbar plexus block; (2) GA-PCA group receiving general anaesthesia and postoperative analgesia by morphine patient-controlled analgesia; (3) GA-LPB group receiving general anaesthesia and postoperative analgesia by lumbar plexus block. Outcome measurements were polysomnographic parameters of sleep architecture and sleep-disordered breathing.ResultsEighteen patients completed the 5-night study protocol (preoperative night: N-1, postoperative nights: N1 to N4). The percentage of rapid eye movement (REM) sleep decreased by 49% and 47% during N1 in the GA-PCA and GA-LPB groups respectively. A rebound phenomenon of more than 40% in the GA-PCA group and 25% in the GA-LPB group was observed during N2 and N3. Apnoea hypopnoea index (AHI) and the number of arousals per hour were significantly increased during N2 and N3 when compared with N-1 in the GA-groups. No sleep architecture disturbances and no sleep-disordered breathing were measured in the S-LPB group.ConclusionPostoperative sleep architecture and breathing pattern were disturbed in GA groups. Both were preserved under spinal anaesthesia associated with a free opioid postoperative analgesia.

The emotion generated by the touch of materials is studied via a protocol based on blind assessment of various stimuli. The human emotional reaction felt toward a material is estimated through (i) explicit measurements, using a questionnaire collecting valence and intensity, and (ii) implicit measurements of the activity of the autonomic nervous system, via a pupillometry equipment. A panel of 25 university students (13 women, 12 men), aged from 18 to 27, tested blind twelve materials such as polymers, sandpapers, wood, velvet and fur, randomly ordered. After measuring the initial pupil diameter, taken as a reference, its variation during the tactile exploration was recorded. After each touch, the participants were asked to quantify the emotional value of the material. The results show that the pupil size variation follows the emotional intensity. It is significantly larger during the touch of materials considered as pleasant or unpleasant, than with the touch of neutral materials. Moreover, after a time period of about 0.5 s following the stimulus, the results reveal significant differences between pleasant and unpleasant stimuli, as well as differences according to gender, i.e., higher pupil dilatation of women than men. These results suggest (i) that the autonomic nervous system is initially sensitive to high arousing stimulation, and (ii) that, after a certain period, the pupil size changes according to the cognitive interest induced and the emotional regulation adopted. This research shows the interest of the emotional characterization of materials for product design.

La prise en compte du point de vue du patient pour évaluer son état de santé est un développement important pour la médecine périopératoire. En complément des monitorages cliniques et paracliniques habituels des patients opérés, elle permet de compléter la séméiologie et ainsi la finesse analytique de l’état de santé des patients récemment opérés. De nombreux outils ont été développés pour recueillir directement le point de vue du patient de manière standardisée et étudiés du point de vue psychométrique. Ces outils permettant l’autoévaluation directe par le patient de son état de santé sont parfois décrits par le terme anglais « Patient-Reported Outcomes Mesures » (PROMs). Ils sont de constructions et caractéristiques très variées. Leurs utilisations principales en médecine périopératoire peuvent se regrouper sous deux axes : 1) en pratique courante pour l’évaluation in situ de la performance des protocoles de soins standardisés, du parcours patient et la personnalisation de la prise en charge ; 2) en recherche clinique en tant que critère de jugement de la qualité des soins. Dans l’ensemble de ces domaines, bien que prometteurs, les PROMs doivent encore faire l’objet d’études visant notamment à caractériser leurs limites méthodologiques et analytiques.Evaluation of patients’ health according to their own subjective point of view is an important add-on for perioperative medicine. In addition to the usual clinical and paraclinical objective monitoring of the surgical patients, these so-called Patient-Reported Outcomes Measures (PROMs) complete the data available for postoperative health assessment and implementation of appropriate corrective measures. Numerous PROMs tools have been developed and psychometrically characterised to directly assess patients’ point of view regarding their health. They represent a heterogeneous group of instruments regarding their design and performances. Their applications in perioperative medicine are mainly relevant in two fields: 1) in clinical healthcare: for the local assessment of the bundles of perioperative care measures, the evaluation of the patient's clinical path, and the development of personalised medicine; 2) in research: as endpoints for healthcare quality assessment. For all these promising directions, further studies are needed to better understand the methodological and analytical strengths and limits of PROMs.

Background: Potential methods for objective assessment of postoperative pain include the Analgesia Nociception Index (TM) (ANI), a real-time index of the parasympathetic tone, the pupillary light reflex (PLR), and the variation coefficient of pupillary diameter (VCPD), a measure of pupillary diameter (PD) fluctuations. Until now, the literature is divided as to their respective accuracy magnitudes for assessing a patient's pain. The VCPD has been demonstrated to strongly correlate with pain in an obstetrical population. However, the pain induced by obstetrical labour is different, given its intermittent nature, than the pain observed during the postoperative period. The aim of the current study was to compare the respective values of these variables at VAS scores >= 4. Methods: After approval by the Ethics Committee, 345 patients aged on average 50 (SD 17) yr (range: 18-91 yr) of age were included. The protocols of general anaesthesia and postoperative analgesia were left to the anaesthetist's discretion. Some 40 min after tracheal intubation, VAS, ANI, PD, PLR, and VCPD values were recorded. Results: VCPD correlates more strongly (r=0.78) with pain as assessed with the VAS than ANI (r=-0.15). PD and PLR are not statistically correlated with VAS. The ability of VCPD to assess the pain of patients (VAS >= 4) is strong [area under the curve (AUC): 0.92, confidence interval (CI): 0.89-0.95], and better than for ANI (AUC: 0.39, CI: 0.33-0.45). Conclusion : Our study suggests that VCPD could be a useful tool for monitoring pain in conscious patients during the postoperative period.

BACKGROUND:Potential methods for objective assessment of postoperative pain include the Analgesia Nociception Index™ (ANI), a real-time index of the parasympathetic tone, the pupillary light reflex (PLR), and the variation coefficient of pupillary diameter (VCPD), a measure of pupillary diameter (PD) fluctuations. Until now, the literature is divided as to their respective accuracy magnitudes for assessing a patient's pain. The VCPD has been demonstrated to strongly correlate with pain in an obstetrical population. However, the pain induced by obstetrical labour is different, given its intermittent nature, than the pain observed during the postoperative period. The aim of the current study was to compare the respective values of these variables at VAS scores ≥4. METHODS:After approval by the Ethics Committee, 345 patients aged on average 50 (SD 17) yr (range: 18-91 yr) of age were included. The protocols of general anaesthesia and postoperative analgesia were left to the anaesthetist's discretion. Some 40 min after tracheal intubation, VAS, ANI, PD, PLR, and VCPD values were recorded. RESULTS:VCPD correlates more strongly (r=0.78) with pain as assessed with the VAS than ANI (r=-0.15). PD and PLR are not statistically correlated with VAS. The ability of VCPD to assess the pain of patients (VAS≥4) is strong [area under the curve (AUC): 0.92, confidence interval (CI): 0.89-0.95], and better than for ANI (AUC: 0.39, CI: 0.33-0.45). CONCLUSIONS:Our study suggests that VCPD could be a useful tool for monitoring pain in conscious patients during the postoperative period. CLINICAL TRIAL REGISTRATION:NCT03267979.

Purpose: To depict the specific brain networks that are modulated by deep brain stimulation (DBS) of the subthalamic nucleus (STN) in Parkinson's disease (PD), using diffusion tensor imaging-based fibre tractography (DTI-FT).Materials and methods: Nine patients who received bilateral STN-DBS for PD were included. Electrodes were localized by co-registering preoperative magnetic resonance imaging and postoperative computed tomography. The volume of tissue activated (VTA) was estimated as an isotropic, spherical electric field distribution centred at each effective electrode contact's centroid coordinates, taking into account individual stimulation parameters (i.e. voltage, impedance). Brain connectivity analysis was undertaken using a deterministic DTI-FT method, seeded from a single region of interest corresponding to the VTA. The labelling of the reconstructed white matter fibre tracts relied on their path and (sub)cortical termination territories.Results: Six months after surgery, we observed a statistically significant reduction in both the Unified Parkinson Disease Rating Scale part III and L-dopa equivalent daily dose. Areas consistently connected to the VTA included the brainstem (100%), cerebellum (94%), dorsal (i.e. supplementary motor area) and lateral premotor cortex (94%), and primary motor cortex (72%). An involvement of the hyperdirect pathway (HDP) connecting the STN and the (pre)motor cortex was demonstrated.Conclusions: The connectivity patterns observed in this study suggest that the therapeutic effects of STN-DBS are mediated through the modulation of distributed, large-scale motor networks. Specifically, the depiction of projection neurons connecting the stimulated area/STN to the (pre)motor cortex, reinforce the growing evidence that the HDP might be a potential therapeutic target in PD. If further replicated, these findings could raise the possibility that DTI-FT reconstruction of the HDP may critically improve DBS targeting and stimulation parameters selection, through the development of programming tools that incorporate VTA modelling and patient-specific DTI-FT data.

Clinical risk factors for postoperative nausea and vomiting (PONV) are usually stratified using the Apfel Score. While a genetic predisposition has recently been demonstrated with the muscarinic acetylcholine receptor (CHRM3) rs2165870 single nucleotide polymorphism (SNP), we investigated whether (1) other SNPs contribute to PONV risk and (2) a genetic risk score might summarise genetic PONV risk.We retrospectively analysed data from a study with 472 patients undergoing elective surgery. We investigated the SNPs rs3218315 (IL2RB), rs349358 (KCNB2), rs703363 (intergenic variant), rs1800497 (DRD2), rs1799971 (OPRM1), and rs1176713 (HTR3A). A genetic risk score was established and association with PONV investigated.Early PONV occurred in 37%. There was a significant association of the KCNB2 rs349358 SNP with nausea (P = 0.021), retching (P = 0.001), and PONV (P = 0.006). The rs349358 genotype distribution was TT in 310 and TC/CC in 155 patients. The KCNB2 SNP was associated with an Odds Ratio (OR) of 1.6 for CT/CC vs. TT (95% CI 1–2.5; P = 0.031) to develop PONV and this was independent from the Apfel Score, and the CHRM3 rs2165870 SNP. A genetic risk score based on the CHRM3 rs2165870 and the KCNB2 rs349358 SNP was created and this genetic score (OR per genetic risk score point: 1.6 (1.3–2.1), P < 0.0001) was independent from the Apfel Score (OR per Apfel score point: 1.6 (1.3–1.9), P < 0.0001) associated with PONV.The KCNB2 rs349358 SNP is also an independent PONV predictor and a genetic risk score has a similar impact on PONV susceptibility compared to the Apfel Score.

SummaryBackgroundGeneral anesthesia dramatically decreases the activity of the autonomic nervous system. Most of the hypnotic agents used to induce anesthesia inhibit sympathetic cardiovascular regulation and baroreflex control in a dose‐dependent manner, lowering cardiac adaptability during the operation. The consequence of this effect in children during and after surgery has never been studied to date.AimThe aim of this study was to follow the variations in autonomic cardiac indices in children younger than 8 years old after general anesthesia (6‐24 hours) in programmed surgery.MethodA prospective descriptive monocentric study of 44 children under 8 years old who underwent scheduled surgery at our hospital center (Saint‐Étienne University Hospital, France) was performed between June 1, 2016 and November 1, 2016. Heart rate variability was monitored for 24 hours using Holter‐ECG devices and the resulting data were interpreted using linear and nonlinear analyses.ResultsCompared to baseline thresholds before surgery, all heart rate variability indices decreased dramatically during general anesthesia. After awakening, a slight reduction in sympathetic activity persisted 6 hours after surgery, but all measurements of sympathetic and parasympathetic activity had returned to baseline thresholds 12 hours after the operation. Twenty‐four hours after surgery, some parameters had increased above the corresponding baseline levels.ConclusionAutonomic nervous function normalizes rapidly (within 12 hours) in prepubertal children. This study indicates that general anesthesia does not seem to increase the long‐term risk of autonomic dysfunction in these patients.

We wish to express our sincere appreciation and thanks to Neice et al 4 Neice A.E. Behrends M. Bokoch M.P. Seligman K.M. Conrad N.M. Larson M.D. Prediction of opioid analgesic efficacy by measurement of pupillary unrest. Anesth Analg. 2017; 124: 915-921 Crossref PubMed Scopus (26) Google Scholar for the finesse and relevance of their analysis of our study, published in The Journal of Pain. 2 Charier D. Zantour D. Pichot V. Chouchou F. Barthélémy J.C. Roche F. Molliex S. Assessing pain using the variation coefficient of pupillary diameter. J Pain. 2017; 18: 1346-1353 Abstract Full Text Full Text PDF PubMed Scopus (17) Google Scholar Pupil Size Variation and Pain—Can the Results be Generalized?The Journal of PainVol. 19Issue 5PreviewI read with great interest the article by Charier et al,2 describing the increase in pupillary size variation (PSV) associated with labor pain. A method of objectively measuring pain has obvious and profound clinical applications. The hypothesis that pain and pupil size variation could be related is quite reasonable, because it has recently been shown that opioids decrease pupil size variation in healthy volunteers,1 and that pupil size variation predicts opioid efficacy in postoperative patients. Full-Text PDF