Neonatal injury modulates incisional pain sensitivity in adulthood: An animal study

Neonatal pain experiences including traumatic injury influences negatively on development of nociceptive circuit developments, resulting in persistent pain hypersensitivity in adults. However, the detailed mechanism is not yet well understood. In the present study, to clarify the pathogenesis of orofacial pain hypersensitivity associated with neonatal injury, the involvement of the voltage-gated sodium channel (Na_v) 1.8 and the C-C chemokine ligand 2 (CCL2)/C-C chemokine receptor 2 (CCR2) signaling in the trigeminal ganglion (TG) in facial skin incisional pain hypersensitivity was examined in 190 neonatal facial-injured and sham male rats. The whisker pad skin was incised on postnatal day 4 and week 7 (Incision-Incision group). Compared to the group without neonatal incision (Sham-Incision group), mechanical hypersensitivity in the whisker pad skin was enhanced in Incision-Incision group. The number of Na_v1.8-immunoreactive TG neurons and the amount of CCL2 expressed in the macrophages and satellite glial cells in the TG were increased on day 14 after re-incision in the Incision-Incision group, compared with Sham-Incision group. Blockages of Na_v1.8 in the incised region and CCR2 in the TG suppressed the enhancement of mechanical hypersensitivity in the Incision-Incision group. Administration of CCL2 into the TG enhanced mechanical hypersensitivity in the Sham-Sham, Incision-Sham and Sham-Incision group. Our results suggest that neonatal facial injury accelerates the TG neuronal hyperexcitability following orofacial skin injury in adult in association with Na_v1.8 overexpression via CCL2 signaling, resulting in the enhancement of orofacial incisional pain hypersensitivity in the adulthood.

Fetal extraction maneuvers during cesarean delivery in the second stage of labor

Objective: To compare maternal and neonatal outcomes following cesarean delivery during second stage of labor, according to the fetal extraction method.Methods: A retrospective cohort study of all women who underwent term cesarean delivery during the second stage of labor at a university-affiliated tertiary medical center (2012-2016). The cohort was divided according to three extraction methods: standard vertex extraction, the push method in which the head extraction is accompanied by pushing through the vagina, and the reverse breech extraction method. Primary outcomes were intraoperative maternal complications, and secondary outcomes were neonatal adverse events.Results: Three hundred and fifty women were included, of whom 206 (59%) underwent standard vertex fetal extraction, 116 (33%) the push method extraction, and 28 (8%) reverse breech extraction. Operation time was significantly shorter in the standard vertex extraction method compared to push and reverse breech extraction methods (33.5 vs. 40.5 and 39.0 min, respectively, p = .013). Uterine laceration and incision extension frequencies were lower in the vertex extraction method as well (24.76 vs. 45.69-46.40% in others, p < .001). Delivery related neonatal injury was significantly more frequent in the reverse breech extraction method (39.29 vs. 12-15% in others, p < .001). In a multivariate analysis reverse breech extraction was associated with higher rates of uterine laceration and incision extension (OR = 2.739 95% confidence interval 1.44-6.56, p = .0237) and delivery related neonatal injury (OR = 2.837, 95% CI: 1.081-7.448, p = .0342).Conclusion: Standard vertex extraction method during second stage of labor cesarean delivery is safer both to the mother and neonate when compared to alternative extraction methods.Abbreviations: NRFHR: non-reassuring fetal heart rate; NICU: neonatal intensive care unit.

A simple model to predict the complicated operative vaginal deliveries using vacuum or forceps

BACKGROUND

Complicated operative vaginal deliveries are associated with high neonatal morbidity and maternal trauma, especially if the procedure is unsuccessful and a cesarean delivery is needed. The decision to perform an operative vaginal delivery has traditionally been based on a subjective assessment by digital vaginal examination combined with the clinical expertise of the obstetrician. Currently there is no method for objectively quantifying the likelihood of successful delivery. Intrapartum ultrasound has been introduced in clinical practice to help predict the progression and final method of delivery.

OBJECTIVE

The aim of this study was to compare predictive models for identifying complicated operative vaginal deliveries (vacuum or forceps) based on intrapartum transperineal ultrasound in nulliparous women.

STUDY DESIGN

We performed a prospective cohort study in nulliparous women at term with singleton pregnancies and full dilatation who underwent intrapartum transperineal ultrasound evaluation prior to operative vaginal delivery. Managing obstetricians were blinded to the ultrasound data. Intrapartum transperineal ultrasound (angle of progression, progression distance, and midline angle) was performed immediately before instrument application, both at rest and concurrently with pushing. Intrapartum evaluation of fetal biometric parameters (estimated fetal weight, head circumference, and biparietal diameter) was also carried out. An operative vaginal delivery was classified as complicated when 1 or more of the following complications occurred: ≥3 tractions needed; third- to fourth-degree perineal tear; severe bleeding during episiotomy repair (decrease of ≥2.5 g/dL in the hemoglobin level); or significant traumatic neonatal lesion (subdural-intracerebral hemorrhage, epicranial subaponeurotic hemorrhage, skeletal injuries, injuries to spine and spinal cord, or peripheral and cranial nerve injuries). Six predictive models were evaluated (information available in Table 2).

RESULTS

We recruited 84 nulliparous patients, of whom 5 were excluded because of the difficulty of adequately evaluating the biparietal diameter and head circumference. A total of 79 nulliparous patients were studied (47 vacuum deliveries, 32 forceps deliveries) with 13 cases in the occiput-posterior position. We identified 31 cases of complicated operative vaginal deliveries (19 vacuum deliveries and 12 forceps deliveries). No differences were identified in obstetric, neonatal, or intrapartum characteristics between the 2 study groups (operative uncomplicated vaginal delivery vs operative complicated vaginal delivery), with the following exceptions: estimated fetal weight (3243 ± 425 g vs 3565 ± 330 g; P = .001), biparietal diameter (93.2 ± 2.1 vs 95.2 ± 2.3 mm; P = .001), head circumference (336 ± 12 vs 348 ± 6.4 mm; P = .001), sex (female 62.5% vs 29.0%; P = .010), newborn weight (3258 ± 472 g vs 3499 ± 383 g; P = .027), and number of tractions (median, interquartile range) (1 [1-2] vs 4 [3-5]; P < .0005). To predict complicated operative deliveries, all 6 of the studied models presented an area under the receiver-operating characteristics curve between 0.863 and 0.876 (95% confidence intervals, 0.775-0.950 and 0.790-0.963; P < .0005). The results of the study met the criteria of interpretability and parsimony (simplicity), allowing us to identify a binary logistic regression model based on the angle of progression and head circumference; this model has an area under the receiver-operating characteristics curve of 0.876 (95% confidence interval, 0.790-0.963; P < .0005) and a calibration slope B of 0.984 (95% confidence interval, 0.0.726-1.243; P < .0005).

CONCLUSION

The combination of the angle of progression and the head circumference can predict 87% of complicated operative vaginal deliveries and can be performed in the delivery room.

Microglia: a newly discovered role in visceral hypersensitivity?

Given the growing body of evidence for a role of glia in pain modulation, it is plausible that the exaggerated visceral pain in chronic conditions might be regulated by glial activation. In this study, we have investigated a possible role for microglia in rats with chronic visceral hypersensitivity and previously documented altered neuronal function. Experiments were performed on adult male Sprague-Dawley rats pre-treated with neonatal colon irritation (CI) and on control rats. Effects of fractalkine (FKN, a chemokine involved in neuron-to-microglia signaling) and of minocycline (an inhibitor of microglia) on visceral sensitivity were examined. Visceral sensitivity was assessed by recording the electromyographic (EMG) responses to graded colorectal distension (CRD) in mildly sedated rats. Responses to CRD were recorded before and after injection of FKN, minocycline or vehicle. Somatic thermal hyperalgesia was measured by latency of paw withdrawal to radiant heat. The pattern and intensity of microglial distribution at L6-S2 in the spinal cord was also compared in rats with CI and controls by fluorescence microscopy using OX-42. Results show that: (1) FKN significantly facilitated EMG responses to noxious CRD by >52% in control rats. FKN also induced thermal hyperalgesia in control rats, consistent with previous reports; (2) minocycline significantly inhibited EMG responses to noxious CRD by >70% in rats with CI compared to controls 60 min after injection. The anti-nociceptive effect of minocycline lasted for 180 min in rats with CI, reaching peak values 60 min after injection. Our results show that FKN enhances visceral and somatic nociception, whereas minocycline inhibits visceral hypersensitivity in chronically sensitized rats, which indicates a role for microglia in visceral hypersensitivity.