[Show abstract][Hide abstract] ABSTRACT: The aim of this study was to determine the reliability of the conditioned pain modulation (CPM) paradigm assessed by an objective electrophysiological method, the nociceptive withdrawal reflex (NWR), and psychophysical measures, using hypothetical sample sizes for future studies as analytical goals. Thirty-four healthy volunteers participated in two identical experimental sessions, separated by 1 to 3 weeks. In each session, the cold pressor test (CPT) was used to induce CPM, and the NWR thresholds, electrical pain detection thresholds and pain intensity ratings after suprathreshold electrical stimulation were assessed before and during CPT. CPM was consistently detected by all methods, and the electrophysiological measures did not introduce additional variation to the assessment. In particular, 99% of the trials resulted in higher NWR thresholds during CPT, with an average increase of 3.4 mA (p<0.001). Similarly, 96% of the trials resulted in higher electrical pain detection thresholds during CPT, with an average increase of 2.2 mA (p<0.001). Pain intensity ratings after suprathreshold electrical stimulation were reduced during CPT in 84% of the trials, displaying an average decrease of 1.5 points in a numeric rating scale (p<0.001). Under these experimental conditions, CPM reliability was acceptable for all assessment methods in terms of sample sizes for potential experiments. The presented results are encouraging with regards to the use of the CPM as an assessment tool in experimental and clinical pain.
PLoS ONE 06/2014; 9(6):e100241. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Translational research has not yet elucidated whether alterations in central pain processes are related to peripheral inflammatory processes in chronic pain patients. We tested the hypothesis that the concentration of cytokines in the peritoneal fluid of endometriosis patients with chronic pain correlate with parameters of hyperexcitability of the nociceptive system. The concentrations of 15 peritoneal fluid cytokines were measured in 11 patients with chronic pelvic pain and a diagnosis of endometriosis. Six parameters assessing central pain processes were recorded. Positive correlations between concentration of some cytokines in the peritoneal fluid and amplification of central pain processing were found. The results suggest that inflammatory mechanisms may be important in the pathophysiology of altered central pain processes and that cytokines produced in the environment of endometriosis could act as mediators between the peripheral lesion and changes in central nociceptive processes.
Regional anesthesia and pain medicine 04/2014; · 4.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The nociceptive withdrawal reflex (NWR) has been proven to be a valuable tool in the objective assessment of central hyperexcitability in the nociceptive system at spinal level that is present in some chronic pain disorders, particularly chronic low back and neck pain. However, most of the studies on objective assessment of central hyperexcitability focus on population differences between patients and healthy individuals and do not provide tools for individual assessment. In this study, a prediction model was developed to objectively assess central hyperexcitability in individuals. The method is based on statistical properties of the EMG signals associated with the nociceptive withdrawal reflex. The model also supports individualized assessment of patients, including an estimation of the confidence of the predicted result.
up to 80% classification rates were achieved when differentiating between healthy volunteers and chronic low back and neck pain patients. EMG signals recorded after stimulation of the anterolateral and heel regions and of the sole of the foot presented the best prediction rates.
A prediction model was proposed and successfully tested as a new approach for objective assessment of central hyperexcitability in the nociceptive system, based on statistical properties of EMG signals recorded after eliciting the NWR. Therefore, the present statistical prediction model constitutes a first step towards potential applications in clinical practice.
[Show abstract][Hide abstract] ABSTRACT: Background
Mechanistic, translational, human experimental pain assessment technologies (pain biomarkers) can be used for: (1) profiling the responsiveness of various pain mechanisms and pathways in healthy volunteers and pain patients, and (2) profiling the effect of new or existing analgesic drugs or pain management procedures. Translational models, which may link mechanisms in animals to humans, are important to understand pain mechanisms involved in pain patients and as tools for drug development. This is urgently needed as many drugs which are effective in animal models fail to be efficient in patients as neither the mechanisms involved in patients nor the drugs’ mechanistic actions are known.
The aim of the present topical review is to provide the basis for how to use mechanistic human experimental pain assessment tools (pain biomarkers) in the development of new analgesics and to characterise and diagnose pain patients. The future aim will be to develop such approaches into individualised pain management regimes.
Experimental pain biomarkers can tease out mechanistically which pain pathways and mechanisms are modulated in a given patient, and how a given compound modulates them. In addition, pain biomarkers may be used to assess pain from different structures (skin, muscle and viscera) and provoke semi-pathophysiological conditions (e.g. hyperalgesia, allodynia and after-sensation) in healthy volunteers using surrogate pain models.
With this multi-modal, multi-tissue, multi-mechanism pain assessment regime approach, new opportunities have emerged for profiling pain patients and optimising drug development. In this context these technologies may help to validate targets (proof-of-concept), provide dose–response relationships, predicting which patient population/characteristics will respond to a given treatment (individualised pain management), and hence provide better understanding of the underlying cause for responders versus non-responders to a given treatment.
In recent years, pain biomarkers have been substantially developed to have now a role to play in early drug development, providing valuable mechanistic understanding of the drug action and used to characterise/profile pain patients. In drug development phase I safety volunteer studies, pain biomarkers can provide indication of efficacy and later if feasible be included in clinical phase II, III, and IV studies to substantiate mode-of-action.
Refining and optimising the drug development process ensures a higher success rate, i.e. not discarding drugs that may be efficient and not push non-efficient drugs too far in the costly development process. Mechanism-based pain bio-markers can help to qualify the development programmes and at the same time help qualifying them by pain profiling (phenotyping) and recognising the right patients for specific trials. The success rate from preclinical data to clinical outcome may be further facilitated by using specific translational pain bio-markers. As human pain biomarkers are getting more and more advanced it could be expected that FDA and EMA in the future will pay more attention to such mechanism-related measures in the approval phase as proof-of-action.
Scandinavian Journal of Pain 10/2013; 4(4):226–230.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND AND OBJECTIVES: Quantitative sensory testing (QST) is widely used to investigate peripheral and central sensitization. However, the comparative performance of different QST for diagnostic or prognostic purposes is unclear. We explored the discriminative ability of different quantitative sensory tests in distinguishing between patients with chronic neck pain and pain-free control subjects and ranked these tests according to the extent of their association with pain hypersensitivity. METHODS: We performed a case-control study in 40 patients and 300 control subjects. Twenty-six tests, including different modalities of pressure, heat, cold, and electrical stimulation, were used. As measures of discrimination, we estimated receiver operating characteristic curves and likelihood ratios. RESULTS: The following quantitative sensory tests displayed the best discriminative value: (1) pressure pain threshold at the site of the most severe neck pain (fitted area under the receiver operating characteristic curve, 0.92), (2) reflex threshold to single electrical stimulation (0.90), (3) pain threshold to single electrical stimulation (0.89), (4) pain threshold to repeated electrical stimulation (0.87), and (5) pressure pain tolerance threshold at the site of the most severe neck pain (0.86). Only the first 3 could be used for both ruling in and out pain hypersensitivity. CONCLUSIONS: Pressure stimulation at the site of the most severe pain and parameters of electrical stimulation were the most appropriate QST to distinguish between patients with chronic neck pain and asymptomatic control subjects. These findings may be used to select the tests in future diagnostic and longitudinal prognostic studies on patients with neck pain and to optimize the assessment of localized and spreading sensitization in chronic pain patients.
Regional anesthesia and pain medicine 06/2013; · 4.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Chronic pain is associated with generalized hypersensitivity and impaired endogenous pain modulation (conditioned pain modulation; CPM). Despite extensive research, their prevalence in chronic pain patients is unknown. This study investigated the prevalence and potential determinants of widespread central hypersensitivity and described the distribution of CPM in chronic pain patients. METHODS: We examined 464 consecutive chronic pain patients for generalized hypersensitivity and CPM using pressure algometry at the second toe and cold pressor test. Potential determinants of generalized central hypersensitivity were studied using uni- and multivariate regression analyses. Prevalence of generalized central hypersensitivity was calculated for the 5th, 10th and 25th percentile of normative values for pressure algometry obtained by a previous large study on healthy volunteers. CPM was addressed on a descriptive basis, since normative values are not available. RESULTS: Depending on the percentile of normative values considered, generalized central hypersensitivity affected 17.5-35.3% of patients. 23.7% of patients showed no increase in pressure pain threshold after cold pressor test. Generalized central hypersensitivity was more frequent and CPM less effective in women than in men. Unclearly classifiable pain syndromes showed higher frequencies of generalized central hypersensitivity than other pain syndromes. CONCLUSIONS: Although prevalent in chronic pain, generalized central hypersensitivity is not present in every patient. An individual assessment is therefore required in order to detect altered pain processing. The broad basic knowledge about central hypersensitivity now needs to be translated into concrete clinical consequences, so that patients can be offered an individually tailored mechanism-based treatment.
European journal of pain (London, England) 05/2013; · 3.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Pain hypersensitivity has been consistently detected in chronic pain conditions, but the underlying mechanisms are difficult to investigate in humans and thus poorly understood. Patients with endometriosis pain display enlarged reflex receptive fields (RRF), providing a new perspective in the identification of possible mechanisms behind hypersensitivity states in humans. The primary hypothesis of this study was that RRF are enlarged in patients with musculoskeletal pain. Secondary study end points were subjective pain thresholds and nociceptive withdrawal reflex (NWR) thresholds after single and repeated (temporal summation) electrical stimulation. Forty chronic neck pain patients, 40 chronic low back pain patients, and 24 acute low back pain patients were tested. Electrical stimuli were applied to 10 sites on the sole of the foot to quantify the RRF, defined as the area of the foot from where a reflex was evoked. For the secondary end points, electrical stimuli were applied to the cutaneous innervation area of the sural nerve. All patient groups presented enlarged RRF areas compared to pain-free volunteers (P<.001). Moreover, they also displayed lower NWR and pain thresholds to single and repeated electrical stimulation (P<.001). These results demonstrate that musculoskeletal pain conditions are characterized by enlarged RRF, lowered NWR and pain thresholds, and facilitated temporal summation, most likely caused by widespread spinal hyperexcitability. This study contributes to a better understanding of the mechanisms underlying these pain conditions, and it supports the use of the RRF and NWR as objective biomarkers for pain hypersensitivity in clinical and experimental pain research.
[Show abstract][Hide abstract] ABSTRACT: Compounds that act on GABA-receptors produce anti-hyperalgesia in animal models, but little is known on their effects in humans. The aim of this study was to explore the potential usefulness of GABA-agonism for the control of pain in humans. Two agonists at the benzodiazepine-binding site of GABAA-receptors (clobazam and clonazepam) were studied using multiple experimental pain tests. Positive results would support further investigation of GABA agonism for the control of clinical pain.
In a randomized double-blind crossover design, 16 healthy male volunteers received clobazam 20 mg, clonazepam 1 mg and tolterodine 1 mg (active placebo). The area of static hyperalgesia after intradermal capsaicin injection was the primary endpoint. Secondary endpoints were: area of dynamic hyperalgesia, response to von Frey hair stimulation, pressure pain thresholds, conditioned pain modulation, cutaneous and intramuscular electrical pain thresholds (1, 5 and 20 repeated stimulation), and pain during cuff algometry.
For the primary endpoint, an increase in the area of static hyperalgesia was observed after administration of placebo (p<0.001), but not after clobazam and clonazepam. Results suggestive for an anti-hyperalgesic effect of the benzodiazepines were obtained with all three intramuscular pain models and with cuff algometry. No effect could be detected with the other pain models employed.
Collectively, the results are suggestive for a possible anti-hyperalgesic effect of drugs acting at the GABAA-receptors in humans, particularly in models of secondary hyperalgesia and deep pain. The findings are not conclusive, but support further clinical research on pain modulation by GABAergic drugs. Because of the partial results, future research should focus on compounds acting selectively on subunits of the GABA complex, which may allow the achievement of higher receptor occupancy than unselective drugs. Our data also provide information on the most suitable experimental models for future investigation of GABAergic compounds.
PLoS ONE 03/2013; 8(3):e43896. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: /st>Ilioinguinal (IL) and iliohypogastric (IH) nerve blocks are used in patients with chronic postherniorrhaphy pain. The present study tested the hypothesis that our method, previously developed in cadavers, blocks the nerves separately and selectively in human volunteers. METHODS: /st>We blocked the IL and the IH nerves in 16 volunteers in a single-blinded randomized cross-over setting under direct ultrasound visualization, by injecting two times the ED95 volume of 1% mepivacaine needed to block a peripheral nerve. The anaesthetized skin areas were tested by pinprick and marked on the skin. A digital photo was taken. For further analysis, the parameterized picture data were transformed into a standardized and unified coordinate system to compare and calculate the overlap of the anaesthetized skin areas of the two nerves on each side. An overlap <25% was defined as selective block. RESULTS: /st>Fifty nerve blocks could be analysed. The mean volume injected to block a single nerve was 0.9 ml. Using ultrasound, we observed spread from one nerve to the other in 12% of cases. The overlap of the anaesthetized skin areas of the nerves was 60.3% and did not differ after exclusion of the cases with visible spread of local anaesthetic from one nerve to the other. CONCLUSIONS: /st>The IL and IH nerves cannot be selectively blocked even if volumes below 1 ml are used. The most likely explanation is the spread of local anaesthetic from one nerve to the other, although this could not be directly observed in most cases.
BJA British Journal of Anaesthesia 03/2013; · 4.24 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVES:: Widespread central hypersensitivity and altered conditioned pain modulation (CPM) have been documented in chronic pain conditions. Information on their prognostic values is limited. This study tested the hypothesis that widespread central hypersensitivity (WCH) and altered CPM, assessed during the chronic phase of low back and neck pain, predict poor outcome. METHODS:: A total of 169 consecutive patients with chronic low back or neck pain, referred to the pain clinic during 1 year, were analyzed. Pressure pain tolerance threshold at the second toe and tolerance time during cold pressor test at the hand assessed WCH. CPM was measured by the change in pressure pain tolerance threshold (test stimulus) after cold pressor test (conditioning stimulus). A structured telephone interview was performed 12 to 15 months after testing to record outcome parameters. Linear regression models were used, with average and maximum pain intensity of the last 24 hours at follow-up as endpoints. Multivariable analyses included sex, age, catastrophizing scale, Beck Depression Inventory, pain duration, intake of opioids, and type of pain syndrome. RESULTS:: Statistically significant reductions from baseline to follow-up were observed in pain intensity (P<0.001). No evidence for an association between the measures of WCH or CPM and intensity of chronic pain at follow-up was found. DISCUSSION:: A major predictive value of the measures that we used is unlikely. Future studies adopting other assessment modalities and possibly standardized treatments are needed to further elucidate the prognostic value of WCH and altered CPM in chronic pain.
The Clinical journal of pain 01/2013; · 2.70 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND:: In a previous observational study, thoracic epidural analgesia (TEA) after open renal surgery resulted in clinically relevant postvoid residuals (PVRs). This study aimed to investigate the individual contribution of epidurally administrated drugs and surgery in bladder dysfunction. METHODS:: In this single-center, parallel-group, randomized (computer-generated list), double-blind superiority trial, 40 patients undergoing open renal surgery were equally allocated to receive epidural bupivacaine (0.125%) alone or with fentanyl (2 µg/ml). Patients underwent urodynamic investigations before TEA and during TEA preoperatively and postoperatively. Primary outcome was the difference (Δ) in PVR between before TEA and postoperatively during TEA. Secondary outcomes were changes in detrusor pressure at maximum flow rate, bladder compliance, and ΔPVR between different time points. RESULTS:: Median ΔPVR (ml) from baseline to postoperatively was 180 (range, -85 to 645; P = 0.001) in the bupivacaine group and 235 (range, 0-580; P value less than 0.001) in the bupivacaine/fentanyl group, with no difference between groups (95% confidence interval, -167 to 103; P = 0.634). Detrusor pressure at maximum flow rate (cm H2O) from baseline was more pronounced in the bupivacaine/fentanyl than that in the bupivacaine group preoperatively (-10; range, -64 to -2; P value less than 0.001 vs. -3; range, -35 to 13; P = 0.397) (P = 0.045) and postoperatively (-18; range, -64 to 0; P value less than 0.001 vs. -12; range, -34 to 22; P = 0.006) (P = 0.135). Surgery did not affect PVRs, but a decreased bladder compliance was observed in both groups. No adverse events occurred. CONCLUSIONS:: Thoracic epidurally administrated bupivacaine resulted in clinically relevant PVRs based on impaired detrusor function. The addition of fentanyl enhanced this effect without generating greater PVRs. After surgery, the voiding phase was not further impaired; however, bladder compliance was decreased.
[Show abstract][Hide abstract] ABSTRACT: There is evidence that perioperative intravenous lidocaine administration can reduce analgesic requirement, improve recovery of bowel function and shorten the length of hospital stay. Its effect in laparoscopic renal surgery has not been investigated.
To evaluate the effect of systemic lidocaine on the length of hospital stay, readiness for discharge, opioid requirement, bowel function and inflammatory and stress response after laparoscopic renal surgery.
Randomised, double-blind, placebo-controlled study.
Single tertiary centre where the study was carried out between July 2009 and February 2011.
Sixty-four patients completed the study. Inclusion criteria were laparoscopic renal surgery and American Society of Anesthesiologists physical status I to III. Exclusion criteria were steroid therapy, chronic opioid therapy, allergy to lidocaine, pre-existing bowel dysfunction and arrhythmia.
Lidocaine was given as a 1.5 mg kg bolus during induction of anaesthesia, followed by an intraoperative infusion of 2 and 1.3 mg kg h for 24 h postoperatively. Primary outcome was the length of hospital stay. Secondary outcomes were readiness for discharge, opioid consumption, sedation, incidence of postoperative nausea and vomiting (PONV), return of bowel function and inflammatory and stress responses.
Length of hospital stay.
The length of hospital stay did not differ between the groups [6 days for the lidocaine group, interquartile range (IQR) 5 to 7, range 2 to 8 vs. 5 days for the placebo group, IQR 5 to 6, range 2 to 11; P = 0.24). Lidocaine had no effect on readiness for discharge [4 days for the lidocaine group (IQR 5 to 7, range 2 to 8) vs. 4 days for the placebo group (IQR 5 to 7, range 2 to 11); P = 0.26], opioid consumption, postoperative sedation, PONV, return of bowel function and plasma concentrations of C-reactive protein, procalcitonin and cortisol.
Systemic perioperative lidocaine administration over 24 h did not influence the length of the hospital stay, readiness for discharge, opioid consumption, return of bowel function or inflammatory and stress responses after laparoscopic renal surgery.
ClinicalTrials.gov identifier NCT00789620.
European Journal of Anaesthesiology 08/2012; 29(11):537-43. · 2.79 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Low back pain is associated with plasticity changes and central hypersensitivity in a subset of patients. We performed a case-control study to explore the discriminative ability of different quantitative sensory tests in distinguishing between 40 cases with chronic low back pain and 300 pain-free controls, and to rank these tests according to the extent of their association with chronic pain. Gender, age, height, weight, body mass index, and psychological measures were recorded as potential confounders. We used 26 quantitative sensory tests, including different modalities of pressure, heat, cold, and electrical stimulation. As measures of discrimination, we estimated receiver operating characteristics (ROC) and likelihood ratios. Six tests seemed useful (in order of their discriminative ability): (1) pressure pain detection threshold at the site of most severe pain (fitted area under the ROC, 0.87), (2) single electrical stimulation pain detection threshold (0.87), (3) single electrical stimulation reflex threshold (0.83), (4) pressure pain tolerance threshold at the site of most severe pain (0.81), (5) pressure pain detection threshold at suprascapular region (0.80), and (6) temporal summation pain threshold (0.80). Pressure and electrical pain modalities seemed most promising and may be used for diagnosis of pain hypersensitivity and potentially for identifying individuals at risk of developing chronic low back pain over time.
[Show abstract][Hide abstract] ABSTRACT: Cervical zygapophysial joint nerve blocks typically are performed with fluoroscopic needle guidance. Descriptions of ultrasound-guided block of these nerves are available, but only one small study compared ultrasound with fluoroscopy, and only for the third occipital nerve. To evaluate the potential usefulness of ultrasound-guidance in clinical practice, studies that determine the accuracy of this technique using a validated control are essential. The aim of this study was to determine the accuracy of ultrasound-guided nerve blocks of the cervical zygapophysial joints using fluoroscopy as control.
Sixty volunteers were studied. Ultrasound-imaging was used to place the needle to the bony target of cervical zygapophysial joint nerve blocks. The levels of needle placement were determined randomly (three levels per volunteer). After ultrasound-guided needle placement and application of 0.2 ml contrast dye, fluoroscopic imaging was performed for later evaluation by a blinded pain physician and considered as gold standard. Raw agreement, chance-corrected agreement κ, and chance-independent agreement Φ between the ultrasound-guided placement and the assessment using fluoroscopy were calculated to quantify accuracy.
One hundred eighty needles were placed in 60 volunteers. Raw agreement was 87% (95% CI 81-91%), κ was 0.74 (0.64-0.83), and Φ 0.99 (0.99-0.99). Accuracy varied significantly between the different cervical nerves: it was low for the C7 medial branch, whereas all other levels showed very good accuracy.
Ultrasound-imaging is an accurate technique for performing cervical zygapophysial joint nerve blocks in volunteers, except for the medial branch blocks of C7.
[Show abstract][Hide abstract] ABSTRACT: The suprascapular nerve (SSN) block is frequently performed for different shoulder pain conditions and for perioperative and postoperative pain control after shoulder surgery. Blind and image-guided techniques have been described, all of which target the nerve within the supraspinous fossa or at the suprascapular notch. This classic target point is not always ideal when ultrasound (US) is used because it is located deep under the muscles, and hence the nerve is not always visible. Blocking the nerve in the supraclavicular region, where it passes underneath the omohyoid muscle, could be an attractive alternative.
In the first step, 60 volunteers were scanned with US, both in the supraclavicular and the classic target area. The visibility of the SSN in both regions was compared. In the second step, 20 needles were placed into or immediately next to the SSN in the supraclavicular region of 10 cadavers. The accuracy of needle placement was determined by injection of dye and following dissection.
In the supraclavicular region of volunteers, the nerve was identified in 81% of examinations (95% confidence interval [CI], 74%-88%) and located at a median depth of 8 mm (interquartile range, 6-9 mm). Near the suprascapular notch (supraspinous fossa), the nerve was unambiguously identified in 36% of examinations (95% CI, 28%-44%) (P < 0.001) and located at a median depth of 35 mm (interquartile range, 31-38 mm; P < 0.001). In the cadaver investigation, the rate of correct needle placement of the supraclavicular approach was 95% (95% CI, 86%-100%).
Visualization of the SSN with US is better in the supraclavicular region as compared with the supraspinous fossa. The anatomic dissections confirmed that our novel supraclavicular SSN block technique is accurate.
Regional anesthesia and pain medicine 02/2012; 37(3):325-8. · 4.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Diffuse noxious inhibitory control (DNIC) is described as one possible mechanism of acupuncture analgesia. This study investigated the analgesic effect of acupuncture without stimulation compared to nonpenetrating sham acupuncture (NPSA) and cold-pressor-induced DNIC. Forty-five subjects received each of the three interventions in a randomized order. The analgesic effect was measured using pressure algometry at the second toe before and after each of the interventions. Pressure pain detection threshold (PPDT) rose from 299 kPa (SD 112 kPa) to 364 kPa (SD 144), 353 kPa (SD 135), and 467 kPa (SD 168) after acupuncture, NPSA, and DNIC test, respectively. There was no statistically significant difference between acupuncture and NPSA at any time, but a significantly higher increase of PPDT in the DNIC test compared to acupuncture and NPSA. PPDT decreased after the DNIC test, whereas it remained stable after acupuncture and NPSA. Acupuncture needling at low pain stimulus intensity showed a small analgesic effect which did not significantly differ from placebo response and was significantly less than a DNIC-like effect of a painful noninvasive stimulus.
Evidence-based Complementary and Alternative Medicine 01/2012; 2012:785613. · 1.72 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The most common techniques to perform stellate ganglion blocks (SGBs) are the blind C6 approach and the fluoroscopic-controlled paratracheal C7 approach, both after manual dislocation of the large vessels. Complications due to vascular or esophageal puncture have been reported. The goal of this ultrasound imaging study was to determine how frequently hazardous structures are located along the needle path of conventional SGB and to determine the influence of the dislocation maneuver on their position.
Sixty volunteers were examined on both sides. The presence of the esophagus, vertebral artery, and other arteries located within the needle path of an SGB at the C6 and C7 levels was determined before and during the dislocation maneuver.
On the left side, the esophagus was located along the needle path in 22 and 39 of 60 cases at the C6 and C7 levels, respectively, and remained there in 10 and 22 of 60 cases during dislocation. The esophagus appeared in the needle path during dislocation from a previously safe location in 5 and 8 of these cases at the C6 and C7 locations, respectively. The vertebral artery was located in the needle path in a range of 2 to 8 of 60 cases without impact of dislocation on its position. Other arteries were located in the needle path in the range of 10 to 17 of 60 cases with a slight decrease during dislocation.
The esophagus and relevant arteries were frequently located in the needle path of conventional SGBs. The dislocation maneuver had a partial impact on moving these structures away from the target and may increase left-sided esophageal puncture risk in certain individuals. Ultrasound (US) imaging is expected to improve the safety of SGB, but it will require clinical trials to confirm this expectation.
Regional anesthesia and pain medicine 12/2011; 37(2):224-7. · 4.16 Impact Factor