Autonomic symptoms have been long noticed coming along with pain in the head, e.g. Trigeminal Neuralgia, trigeminal autonomic cephalalgias. The symptoms show up during pain attacks, so they are assumed to be activated by the nociceptive afferents of the trigeminal nerve. Here, we present a case with hypersalivation as the complication after percutaneous balloon compression for trigeminal neuralgia, although the patient was pain-free after the treatment. A 71-year-old female with excessive salivation on the affected side after percutaneous balloon compression is described. The patient underwent microvascular decompression several years ago, and both the microvascular decompression and the preoperative imaging examination confirmed that there was no offending vessel at the root entry zone of the trigeminal nerve. After the percutaneous balloon compression, the patient was free of pain, but the autonomic symptoms (hypersalivation) still showed up. The autonomic symptoms which usually came along with pain presented solely as post-percutaneous balloon compression complication in the case. Contrary to popular belief, for the patient who was pain-free after percutaneous balloon compression, the transiently overactivated nerve fibers that led to hypersalivation were not nociceptive afferents of the trigeminal nerve.

Dorsal root ganglion stimulation (DRG-S) has recently emerged as a novel therapy in neuromodulation that demonstrated a higher rate of success than spinal cord stimulation (SCS) in a prospective, head-to-head randomized comparative trial to treat complex regional pain syndrome (CRPS) and causalgia. In contrast to SCS, DRG-S also shows promise in treating conditions that are not purely neuropathic such as axial low back pain, which has a prominent nociplastic pain component. It is not known to what extent the effectiveness of DRG-S for such indications is due to effective treatment of the neuropathic pain component versus the effects of DRG-S on mechanical pain. Although rarely studied, reporting outcomes of DRG-S to treat predominantly mechanical/nociceptive pain may help point toward expanding the utility of this therapy. Here, we present five cases of refractory mechanical pain treated with DRG-S.
A retrospective analysis of all patients who underwent a successful DRG-S trial and implant between September 2017 and September 2021 at our institute was performed. Patients who had intractable joint pain without strong evidence of neuropathic pain were included in this case series. The Budapest criteria for CRPS, the Douleur Neuropathique 4 Questions (DN4) survey, or a definable nerve injury were used to determine the presence of neuropathic pain. Baseline assessments for pain (Numeric Rating Scale [NRS]), function (Oswestry Disability Index [ODI]), quality of life (EuroQol-5 Dimension [EQ-5D]), and other applicable joint surveys were extracted from pre-trial baseline and follow-up appointments.
Five patients were identified and included. Patient diagnoses consisted of refractory joint pain of the hip, knee, or ankle. Mean NRS pain scores improved by 74% from 9.2 at baseline to 2.4 at the last follow-up (mean = 28 months post-implant). From baseline to the last follow-up, mean ODI scores improved by 65% from 66 to 23 and EQ-5D scores more than doubled from an average of 0.371 to 0.797.
This clinical report illustrates the potential utility DRG-S has in treating pain that clinically presents as predominantly refractory mechanical joint pain without a significant neuropathic component. The physiological reasons for our observations may be that DRG-S is able to directly influence the conduction of nociceptive signaling at the DRG and within the spinal cord. Further investigations are warranted to determine if DRG-S is a potential treatment option for chronic mechanical pain.

Background : Although an increase in sympathetic nerve activity is generally associated with a decrease in the photoplethysmography (PPG) amplitude, the present case study demonstrates that nociceptive stimuli, such as tracheal intubation, paradoxically induce an increase in PPG amplitude. To the best of our knowledge, this is the first study to capture an increase in the PPG amplitude in response to sympathetic nerve activation. Case presentation : A 73-year-old woman underwent open surgery. Following anesthesia induction, tracheal intubation was performed, which resulted in increased heart rate and raised blood pressure. While nociception usually decreases the PPG amplitude, the opposite was found. Conversely, the vascular stiffness K value, our research group\'s unique monitoring method to quantify the strength of sympathetic activity, increased reflecting increased peripheral vascular resistance. Conclusions : We report a paradoxical case of increased PPG amplitude following tracheal intubation. It is important to note that the PPG amplitude does not always decrease with nociceptive stimuli. J. Med. Invest. 68 : 383-385, August, 2021.

Nociception is the detection of noxious stimulation by the nervous system. The PMD-200 monitor is a validated, emerging technology for intraoperative monitoring using the nociception level (NOL) index. We describe a pediatric case of an open resection of paraganglionic masses during which episodic increases in NOL index and blood pressure coincided with tumor manipulation, presumably due to a catecholamine surge. Since the patient was under stable and adequate analgesia, the increases in NOL index likely reflected the physiologic effects of tumor handling rather that the presence of a true noxious stimulus. Clinicians should consider this limitation when using this monitor.

BACKGROUND: Opioid-free anesthesia decreases the incidence of opioid adverse events, but its optimal antinociceptive depth has not been clearly defined. Personalizing intraoperative opioid-free infusions with a nociception monitor may be the solution.
METHODS: We describe the feasibility and potential limitations of titrating opioid-free antinociception during major abdominal surgery using the Analgesia Nociception Index (Mdoloris, Lille, France) in an obese patient. After stabilizing the patient\'s nociception-antinociception balance intraoperatively we quickly reversed anesthesia and the patient did not require postoperative opioids.
CONCLUSIONS: Personalizing opioid-free antinociception with a nociception monitor is feasible. It may optimize intraoperative antinociception and improve postoperative comfort.

We describe the case of a 68-year-old woman with an acute episode of severe low back pain (LBP) resistant to opioids, who had experienced a sacral insufficiency fracture (SIF) two years earlier. At clinical examination, patient reported constant, dull, non-localizable pain at lumbar and sacral level, exacerbated by paravertebral palpation, particularly at L4-L5 and the sacroiliac joint, with a concomitant and remittent neuropathic component, difficult to localize at lumbar and sacral level. The latest magnetic resonance imaging study revealed disc herniations at L3-L4, L4-L5, and L5-S1 levels. The patient was treated with intramuscularparavertebral injections of oxygen-ozone (O2O3) mixture for 4 weeks (once a week), using a O3 concentration of 20 mcg/mL (5 mL in L4-L5 zone and 5 mL in L5-S1 zone, bilaterally). At 1 week after the first injection, the pain (assessed by Numerical Pain Rating Scale and Brief Pain Inventory) was considerably reduced and the patient\'s health-related quality of life (assessed by Short Form 12-Item Health Survey and European Quality of Life Index) had improved; these findings were confirmed at follow-up 1 month after the last injection. This paradigmatic case of nociplastic pain successfully treated by paravertebral O2O3 therapy might be a starting point for further studies on the effects of this treatment in terms of decreasing pain and improving HRQoL in patients affected by opioid-resistant LBP.

Rett syndrome (RTT), a rare neurodevelopmental disorder occurring primarily in females (1:10-15,000 female live births), is most often caused by loss-of-function mutations in the X-linked methyl-CpG-binding protein 2 gene (MECP2). Clinical observations and preclinical findings indicate apparent abnormal sensory and nociceptive function. There have been no direct investigations of epidermal sensory innervation in patients with RTT.
We compared 3 mm epidermal punch biopsy specimens from adolescent female RTT patients (N = 4, aged 12-19 years) against an archived approximate age-, sex-, body-site matched comparison sample of healthy adolescent females (N = 8, ages 11-17).
Confocal imaging revealed, on average, statistically significant increased epidermal nerve fiber (ENF) peptidergic (co-stained calcitonin gene-related protein [CGRP]) innervation density compared with healthy female control individuals.
Given the clinical phenotype of disrupted sensory function along with diagnostic criteria specific to cold hands/feet and insensitivity to pain, our preliminary observations of ENF peptidergic fiber density differences warrants further investigation of the peripheral neurobiology in RTT.

Analgesia Nociception Index (ANI) has been proposed for the evaluation of the nociception-antinociception balance in the perioperative period. In obese patients, where the management of analgesia may be rendered difficult by pharmacological changes, we hypothesised that the monitoring of analgesia with ANI would reduce intraoperative opioid consumption during bariatric surgery.
This monocentric, observational, unmatched case-control study aimed to compare perioperative data from obese subjects (body mass index ≥35kgm-2) during bariatric surgery with or without the use of ANI monitoring (ANI+ group versus ANI- group). Intraoperative analgesia was provided by injection of sufentanil, which was performed according to the clinician\'s assessment in the ANI- group or to the ANI value in the ANI+ group. The primary outcome was the mean hourly intraoperative sufentanil requirement. Secondary outcomes included the need for postoperative morphine titration, incidence of nausea and vomiting, respiratory distress and pain scores in the first 24hours.
Between December 2013 and September 2016, 60 obese patients (i.e. 30 per group) were included. The mean hourly consumption of sufentanil was significantly lower in the ANI+ group (0.15±0.05μgkg-1h-1 versus 0.17±0.05μgkg-1h-1, P=0.038). We found no difference between groups regarding the incidence of nausea and vomiting, acute respiratory distress, the need for postoperative morphine titration, or pain scores in the first 24 postoperative hours.
The use of ANI monitoring might reduce intraoperative consumption of sufentanil during bariatric surgery but does not appear to be accompanied by a reduction in its side effects.

In thermoneutral conditions, rats display cyclic variations of the vasomotion of the tail and paws, the most widely used target organs in current acute or chronic animal models of pain. Systemic morphine elicits their vasoconstriction followed by hyperthermia in a naloxone-reversible and dose-dependent fashion. The dose-response curves were steep with ED50 in the 0.5-1 mg/kg range. Given the pivotal functional role of the rostral ventromedial medulla (RVM) in nociception and the rostral medullary raphe (rMR) in thermoregulation, two largely overlapping brain regions, the RVM/rMR was blocked by muscimol: it suppressed the effects of morphine. \"On-\" and \"off-\" neurons recorded in the RVM/rMR are activated and inhibited by thermal nociceptive stimuli, respectively. They are also implicated in regulating the cyclic variations of the vasomotion of the tail and paws seen in thermoneutral conditions. Morphine elicited abrupt inhibition and activation of the firing of on- and off-cells recorded in the RVM/rMR. By using a model that takes into account the power of the radiant heat source, initial skin temperature, core body temperature, and peripheral nerve conduction distance, one can argue that the morphine-induced increase of reaction time is mainly related to the morphine-induced vasoconstriction. This statement was confirmed by analyzing in psychophysical terms the tail-flick response to random variations of noxious radiant heat. Although the increase of a reaction time to radiant heat is generally interpreted in terms of analgesia, the present data question the validity of using such an approach to build a pain index.

OBJECTIVE: To establish whether there are differences in pain sensitivity between hypertensive and normotensive older adults.
METHODS: A cross-sectional case control study was carried out. A total of 72 older adults, 36 normotensive and 36 hypertensive, participated in the study. The pressure pain threshold (PPT) was assessed on seven points bilaterally in both groups by means of pressure algometry. Two-factor analysis of variance (anova) - group and sex - was carried out, and the magnitude of the differences was calculated using Cohen\'s index.
RESULTS: The PPT values were higher in the group of hypertensive older adults compared with the normotensive older adults; that difference was significant (P < 0.05) for the following points: right and left trochanters, left trapezium, left L3/L4 and left anterior tibialis muscle, with both trochanter and left L3/L4 PPT showing moderate magnitude of the differences. The correlations shown among the PPT were stronger in the group of hypertensive older adults. Thus, hypoalgesia was more generalized among the hypertensive older adults compared with the normotensive older adults. Sex did not influence that difference, although the magnitude of the difference was greater among men compared with women.
CONCLUSIONS: Hypoalgesia, as assessed by means of PPT, showed a relationship with arterial hypertension in older adults. The influence of sex on hypoalgesia shown by hypertensive individuals is controversial. Geriatr Gerontol Int 2017; 17: 967-972.