Augmented reality in ultrasound-guided regional anaesthesia: useful tool or expensive toy?

Use of augmented reality is increasingly applied in medical education and practice. The main advantage of this technology is the display of relevant information in the visual field of multiple operators. Here we provide a critical analysis of the potential application of augmented reality in regional anaesthesia.

Deltoid muscle contribution to shoulder flexion and abduction strength: an experimental approach.

BACKGROUND: The rotator cuff (RC) and the deltoid muscle are 2 synergistic units that enable the functionally demanding movements of the shoulder. A number of biomechanical studies assume similar force contribution of the force couple (RC and deltoid) over the whole range of motion, whereas others propose position-dependent force distribution. There is a lack of in vivo data regarding the deltoid's contribution to shoulder flexion and abduction strength. This study aimed to create reliable in vivo data quantifying the deltoid's contribution to shoulder flexion and abduction strength throughout the range of motion. METHODS: Active range of motion and isometric muscle strength of shoulder abduction and flexion in 0°, 30°, 60°, 90°, and 120° of abduction/flexion as well as internal and external rotation in 0° and 90° of abduction were obtained in 12 healthy volunteers on the dominant arm before and after an ultrasound-guided isolated axillary nerve block. Needle electromyography was performed before and after the block to confirm deltoid paralysis. Radiographs of the shoulder and an ultrasonographic examination were used to exclude relevant shoulder pathologies. RESULTS: Active range of motion showed a minimal to moderate reduction to 94% and 88% of the preintervention value for abduction and flexion. Internal and external rotation amplitude was not impaired. The abduction strength was significantly reduced to 76% at 0° (P = .002) and to 25% at 120° (P < .001) of abduction. The flexion strength was significantly reduced to 64% at 30° (P < .001) and to 30% at 120° (P < .001) of flexion. The strength reduction was linear, depending on the flexion/abduction angle. The maximal external rotation strength showed a significant decrease to 53% in 90° (P < .001) of abduction, whereas in adduction no strength loss was observed (P = .09). The internal rotation strength remained unaffected in 0° and 90° of abduction (P = .28; P = .13). CONCLUSION: The deltoid shows a linear contribution to maximal shoulder strength depending on the abduction or flexion angle, ranging from 24% in 0° to 75% in 120° of abduction and from 11% in 0° to 70% in 120° of flexion, respectively. The overall contribution to abduction strength is higher than to flexion strength. The combination of deltoid muscle and teres minor contributes about 50% to external rotation strength in 90° of abduction. The internal rotation strength is not influenced by a deltoid paralysis. This study highlights the position-dependent contribution of the shoulder muscles to strength development and thereby provides an empirical approach to better understand human shoulder kinematics.

Dislocation rates of perineural catheters placed either perpendicular or parallel to the femoral nerve: A randomised controlled trial.

BACKGROUND: Ultrasound has increased the efficacy of femoral nerve catheters but their postoperative dislocation still remains a common problem. Although catheter placement parallel to the nerve seems to reduce dislocation rates in other nerves and plexuses, the possible advantage for femoral nerve catheter placement remains unclear. OBJECTIVE: To compare the dislocation rates of femoral catheters when placed perpendicular or parallel to the femoral nerve. DESIGN: Randomised controlled study. SETTING: University orthopaedic hospital. Duration of study: October 2018 to June 2019. PATIENTS: Eighty patients scheduled for major knee surgery with femoral catheter were enrolled and randomly allocated in two groups. Data from 78 patients could be analysed. INTERVENTIONS: The femoral nerve catheters was placed perpendicular to the nerve in Group 1 (n=40), whereas in Group 2 (n=38) parallel to it. For Group 1 the short-axis view of the nerve and an in-plane puncture was used. For Group 2 we used the short-axis view of the nerve and an out-of-plane puncture technique combined with rotation of the transducer to the long-axis view with the needle in-plane. MAIN OUTCOME MEASURES: Primary outcome was the catheter dislocation rate in the first 48 h. Secondary outcomes were pain scores and sensory blockade. RESULTS: There was no statistically significant difference between the two techniques regarding dislocation of the catheters at 24 or 48 h (at 48 h, Group 1: 15%, Group 2: 2.6%, P = 0.109). Also pain scores, sensory blockade and rescue doses of ropivacaine did not differ between the groups. However, in Group 2 the technique took longer. CONCLUSION: Rotating the ultrasound probe to the long-axis in-plane view enabled examination of the catheter position when it was placed parallel to the nerve. The parallel placement of the catheter required more time, but did not significantly improve dislocation rate, pain scores or sensory blockade. TRIAL REGISTRATION: Clinicaltrials.gov identifier: NCT03693755.

Ultrasonography-guided anterior approach for axillary nerve blockade: An anatomical study.

Combined ultrasound (US)-guided blockade of the suprascapular and axillary nerves (ANs) has been proposed as an alternative to interscalene blockade for pain control in shoulder joint pathology or postsurgical care. This technique could help avoid respiratory complications and/or almost total upper limb palsy. Nowadays, the AN blockade is mostly performed using an in-plane caudal-to-cephalic approach from the posterior surface of the shoulder, reaching the nerve immediately after it exits the neurovascular quadrangular space (part of the spatium axillare). Despite precluding most respiratory complications, this approach has not made postsurgical pain relief any better than an interscalene blockade, probably because articular branches of the AN are not blocked.Cephalic-to-caudal methylene blue injections were placed in the first segment of the AN of six Thiel-embalmed cadavers using an US-guided anterior approach in order to compare the distribution with that produced by a posterior approach to the contralateral AN in the same cadaver. Another 21 formalin-fixed cadavers were bilaterally dissected to identify the articular branches of the AN.We found a good spread of the dye on the AN and a constant relationship of this nerve with the subscapularis muscle. The dye reached the musculocutaneous nerve, which also contributes to shoulder joint innervation. We describe the anatomical landmarks for an ultrasonography-guided anterior AN blockade and hypothesize that this anterior approach will provide better pain control than the posterior approach owing to complete blocking of the joint nerve. Clin. Anat. 33:488-499, 2020. © 2019 Wiley Periodicals, Inc.

The effect of experimentally induced gluteal muscle weakness on joint kinematics, reaction forces, and dynamic balance performance during deep bilateral squats.

Squatting is a common daily activity and fundamental exercise in resistance training and closed kinetic chain programs. The aim of this study was to investigate the effects of an experimentally induced weakness of the gluteal muscles on joint kinematics, reactions forces (JRFs), and dynamic balance performance during deep bilateral squats in healthy young adults. Ten healthy adults received sequential blocks of (1) branch of the superior gluteal nerve to the tensor fasciae latae (SGNtfl) muscle, (2) superior gluteal nerve (SGN), and (3) inferior gluteal nerve (IGN) on the dominant right leg. At the control condition and following each block, the participants were instructed to perform deep bilateral squats standing on two force plates. Hip, knee, ankle, and pelvis kinematics did not differ significantly following iatrogenic weakness of gluteal muscles. The most important finding was the significant differences in JRFs following SGN and IGN block, with the affected hip, patellofemoral, and ankle joint demonstrating lower JRFs, whereas the contralateral joints demonstrated significantly higher JRFs, especially the patellofemoral joint which demonstrated an average maximum difference of 1.43 x body weight compared with the control condition. When performing a deep bilateral leg squat under SGN and IGN block, the subjects demonstrated an increased center of pressure (CoP) range and standard deviation (SD) in mediolateral compared with the control condition. These results imply that squat performance changes significantly following weakness of gluteal muscles and should be considered when assessing and training athletes or patients with these injuries.

Perioperative Intravenous Dexamethasone Significantly Reduces Postoperative Opioid Requirement and Nausea After Unilateral Elective Hip Arthroscopy: A Randomized Double-blinded Placebo-controlled Trial.

BACKGROUND: Previous studies have shown that dexamethasone has a positive effect on postoperative pain control, opioid consumption, nausea, and vomiting and length of hospital stay after arthroplasty surgery. PURPOSE/HYPOTHESIS: The purpose of this study was to assess whether adding perioperative dexamethasone to our current pain regimen after hip arthroscopy is more effective than a placebo. It was hypothesized that dexamethasone would reduce postoperative pain, reduce opioid consumption, improve subjective pain and nausea scores, and reduce the number of vomiting events. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: A total of 50 patients requiring unilateral elective hip arthroscopy were randomized to receive intravenous dexamethasone immediately before induction of anesthesia and at 8 am on the first postoperative day (2 ×12 mg) or a placebo (sodium chloride 0.9%). The patient, the surgeons, the treating anesthesiologist, and the involved nursing and physical therapy personnel were blinded to group assignment. The primary outcome was postoperative pain, and secondary outcomes were opioid consumption and nausea scores-assessed using a translated revised version of the American Pain Society Patient Outcome Questionnaire 6 hours postoperatively and on days 1 and 2-and vomiting events. A clinical follow-up was performed 12 weeks postoperatively to assess adverse events. RESULTS: The mean age at inclusion was 29 years in both groups. Postoperative pain levels did not differ significantly in most instances. Opioid requirements during the hospitalization in the dexamethasone group were significantly lower than those in the placebo group (31.96 ± 20.56 mg vs 51.43 ± 38 mg; P = .014). Significantly fewer vomiting events were noted in the dexamethasone group (0.15 ± 0.59 vs 0.65 ± 0.91; P = .034). Descriptive data and surgical parameters did not differ significantly. CONCLUSION: Perioperative intravenous dexamethasone significantly reduced postoperative opioid consumption by 40% without compromising pain level and safety, as no corticosteroid-related side effects were observed. Dexamethasone may be a valuable adjuvant to a multimodal systemic pain regimen after hip arthroscopy. REGISTRATION: NCT04610398 (ClinicalTrials.gov identifier).

Block of the superior cervical ganglion, description of a novel ultrasound-guided technique in human cadavers.

OBJECTIVE: Injection of opioids to the superior cervical ganglion (SCG) has been reported to provide pain relief in patients suffering from different kinds of neuropathic facial pain conditions, such as trigeminal neuralgia, postherpetic neuralgia, and atypical facial pain. The classic approach to the SCG is a transoral technique using a so-called "stopper" to prevent accidental carotid artery puncture. The main disadvantage of this technique is that the needle tip is positioned distant from the actual target, possibly impeding successful block of the SCG. A further limitation is that injection of local anesthetics due to potential carotid artery puncture is contraindicated. We hypothesized that the SCG can be identified and blocked using ultrasound imaging, potentially increasing precision of this technique. INTERVENTIONS: In this pilot study, 20 US-guided simulated blocks of the SCG were performed in 10 human cadavers in order to determine the accuracy of this novel block technique. After injection of 0.1 mL of dye, the cadavers were dissected to evaluate the needle position and coloring of the SCG. RESULTS: Nineteen of the 20 needle tips were located in or next to the SCG. This corresponded to a simulated block success rate of 95% (95% confidence interval 85-100%). In 17 cases, the SCG was completely colored, and in two cases, the caudal half of the SCG was colored with dye. CONCLUSIONS: The anatomical dissections confirmed that our ultrasound-guided approach to the SCG is accurate. Ultrasound could become an attractive alternative to the "blind" transoral technique of SCG blocks.

Detection of heart rate using smartphone gyroscope data: a scoping review.

Heart rate (HR) is closely related to heart rhythm patterns, and its irregularity can imply serious health problems. Therefore, HR is used in the diagnosis of many health conditions. Traditionally, HR has been measured through an electrocardiograph (ECG), which is subject to several practical limitations when applied in everyday settings. In recent years, the emergence of smartphones and microelectromechanical systems has allowed innovative solutions for conveniently measuring HR, such as smartphone ECG, smartphone photoplethysmography (PPG), and seismocardiography (SCG). However, these measurements generally rely on external sensor hardware or are highly susceptible to inaccuracies due to the presence of significant levels of motion artifact. Data from gyrocardiography (GCG), however, while largely overlooked for this application, has the potential to overcome the limitations of other forms of measurements. For this scoping review, we performed a literature search on HR measurement using smartphone gyroscope data. In this review, from among the 114 articles that we identified, we include seven relevant articles from the last decade (December 2012 to January 2023) for further analysis of their respective methods for data collection, signal pre-processing, and HR estimation. The seven selected articles' sample sizes varied from 11 to 435 participants. Two articles used a sample size of less than 40, and three articles used a sample size of 300 or more. We provide elaborations about the algorithms used in the studies and discuss the advantages and disadvantages of these methods. Across the articles, we noticed an inconsistency in the algorithms used and a lack of established standardization for performance evaluation for HR estimation using smartphone GCG data. Among the seven articles included, five did not perform any performance evaluation, while the other two used different reference signals (HR and PPG respectively) and metrics for accuracy evaluation. We conclude the review with a discussion of challenges and future directions for the application of GCG technology.

Accuracy of ultrasound-guided nerve blocks of the cervical zygapophysial joints.

BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: Ultrasound-imaging is an accurate technique for performing cervical zygapophysial joint nerve blocks in volunteers, except for the medial branch blocks of C7.

Vasectomy reversal with ultrasonography-guided spermatic cord block.

UNLABELLED: Study Type--Therapy (case series) Level of Evidence 4. What's known on the subject? and What does the study add? Vasectomy reversal is often performed in general or neuraxial anaesthesia. Even though the site of vasectomy reversal is easily amenable to regional/local anaesthesia, spermatic cord blocks are rarely applied because of their risk of vascular damage within the spermatic cord. Recently, we described the technique of ultrasonography (US)-guided spermatic cord block for scrotal surgery, which, thanks to the US guidance, at the same time avoids the risk of vascular damage of blindly performed injections and the risks of general and neuraxial anaesthesia. Vasectomy reversal can easily be done in regional anaesthesia with the newly described technique of US-guided spermatic cord block without the risks of vascular damage by a blindly performed injection and the risks of standard general and neuraxial anaesthesia. In addition, this technique grants long-lasting postoperative pain relief and patients recover more quickly. Microsurgical conditions are excellent and patient satisfaction is high. Thanks to these advantages, more patients undergoing vasectomy reversal might avoid general or neuraxial anaesthesia. OBJECTIVE: • To assess the success rate, microsurgical conditions, postoperative recovery, complications and patient satisfaction of ultrasonography (US)-guided spermatic cord block in patients undergoing microscopic vasectomy reversal and to compare them to a control group with general or neuraxial anaesthesia. PATIENTS AND METHODS: • The present study comprised a prospective series of 10 consecutive patients undergoing US-guided spermatic cord block for microscopic vasectomy reversal. • The cohort was compared with 10 patients in a historical control group with general or neuraxial anaesthesia. RESULTS: • Nineteen of 20 (95%) blocks were successful, defined as no pain >3 on the Visual Analogue Scale (VAS), no additional analgesics and/or no conversion to general anaesthesia. Median pain was 0 on the VAS (range 0-5). Additional analgesics were requested in one (5%) block, and there was no conversion to general anaesthesia. • Microsurgical conditions were excellent. • In the spermatic cord block vs general/neuraxial anaesthesia groups, median times (range) between surgery and first postoperative analgesics, alimentation, mobilization and hospital discharge were 12 (2-14) vs 3 (1-6), 1 (0.25-3) vs 4 (3-6), 2 (1-3) vs 6 (3-10), and 4 (3-11) vs 8.5 (6-22) h, respectively. • No complications were reported after the spermatic cord block. • Patient satisfaction was excellent. CONCLUSIONS: • US-guided spermatic cord block for microscopic vasectomy reversal is highly successful and provides long-lasting perioperative analgesia. • Times to alimentation, mobilization and hospital discharge are shorter under US-guided spermatic cord block than under general/neuraxial anaesthesia. • Additional anaesthetic pain management might, however, be required unexpectedly with US-guided spermatic cord block.

Inadvertent Placement of an Infraclavicular Catheter in the Interscalene Region With an Unusual Complication: A Case Report.

An infraclavicular catheter is a very efficient technique to provide excellent perioperative anesthesia/analgesia for upper limb surgery. However, complications can occur and are dependent on the technique used. We report the inadvertent placement of an infraclavicular catheter in the interscalene region when an ultrasound-guided infraclavicular catheter was threaded cranially. We proposed some strategies to avoid the occurrence of complications when performing this block.

[Noninvasive Treatments for Acute and Chronic Back Pain]. / Nicht-invasive Therapieansätze bei akuten und chronischen Rückenschmerzen.

Noninvasive Treatments for Acute and Chronic Back Pain Abstract. The therapy of back pain - especially the medication with opioids - can be challenging for the treating physician. Specific back pain can often be diagnosed by imaging and successfully treated by surgery or medication. In contrast, nonspecific back pain can be worsened by inappropriate imaging, questionable surgical indications and uncontrolled drug use. For the therapy of nonspecific back pain, maintaining daily activity and exercise therapy is central. Opioids are effective drugs for short-term use. However, long-term use often leads to opioid-induced hyperalgesia and hormonal dysfunction with decreased quality of life and libido. Furthermore, opioids can lead to abuse and addiction. After an ineffective treatment with non-opioids, opioids may be given for a limited time period (if possible shorter than four weeks) according to international guidelines.

A shortened radiofrequency denervation method for cervical zygapophysial joint pain based on ultrasound localization of the nerves.

OBJECTIVE: Radiofrequency neurotomy is a recognized treatment for cervical zygapophysial joint pain. In several studies, the method has provided complete pain relief in 60-70% of the patients for approximately 9 months. The validated technique has the disadvantage of procedural times of 2-4 hours because several lesions are performed to take into account the variable nerve course. We tested the hypothesis that ultrasound localization of the nerves would enable us to reduce the number of lesions performed, while reaching the benchmark of at least 80% pain relief in 80% of patients with a median duration of 35 weeks, as achieved by a previous investigation using the standard method. INTERVENTIONS: We prospectively studied 15 consecutive patients with diagnosed cervical zygapophysial joint pain. They were treated using a shortened radiofrequency procedure under fluoroscopic control, based on previous ultrasound localization of the joint supplying nerves, with only two thermal lesions performed per nerve. Successful treatment was defined as at least 80% pain relief in the visual analog scale as compared with pretreatment. Follow-up was performed until 12 months after treatment. RESULTS: Of the 15 patients, 14 were successfully treated (93%, 95% confidence interval [CI] 80-100%) with a median time of pain relief of 44 weeks. At 6 and 12 months, 13 (87%, 95% CI 70-100%) and 6 patients (40%, 95% CI 15-65%) reported successful treatment, respectively. The median duration of the procedure was 35 minutes. CONCLUSION: In patients with cervical zygapophysial joint pain, radiofrequency denervation according to a shortened protocol based on ultrasound localization of the nerves reached the benchmark of the standard technique.

Factors determining the success of radiofrequency denervation in lumbar facet joint pain: a prospective study.

BACKGROUND AND AIMS: Radiofrequency denervation (RF) of the lumbar facet joints has been shown to be effective in well-selected patients. However, long-term success varies between studies. We evaluated the influence of selected psychosocial and constitutional factors on the outcome of RF, expressed as the duration of pain relief. METHODS: This prospective observational study included 44 patients who received RF denervations at the University Hospital of Berne. Success was defined as at least 50% pain reduction 7-21 days, 6 months and 1 year after RF therapy. The Cox-regression analysis was performed to evaluate the influence of the following factors on the duration of success: age, sex, depression, work inability and previous surgery. RESULTS: Complete follow-up was available for 41 patients. The success rate 7-21 days after the denervation was 76%. It decreased to 32% at 6 months and to 22% at 1 year. The median success duration was 17 weeks (95% CI 10-26). The Cox-regression analysis showed a significant shorter duration of success for patients with depression (hazard ratio [HR] 2.97, 95% CI 1.32-6.65), previous surgery (HR 2.39, 95% CI 1.10-5.21) and number of treated joints (HR 1.95 for each increase in the number of joints, 95% CI 1.14-3.33). In bivariate analyses, only depression was kept to be significant. CONCLUSIONS: Depression seems to be related with a short duration of success. Based on these findings, a comprehensive study is warranted to evaluate whether psychosocial factors have to be considered when recruiting patients for radiofrequency denervation.

[Peripheral Regional Anaesthesia for Perioperative Analgesia]. / Periphere Regionalanästhesie oder Allgemeinanästhesie ­ eine individuelle Risiko-Nutzen-Abwägung.

Peripheral Regional Anaesthesia for Perioperative Analgesia Abstract. Peripheral regional anaesthesia is the actual gold standard of opioid-sparing perioperative analgesia and is mainly used for surgery of the shoulder, arm and leg. Well-trained anaesthesiologists are the prerequisite for the correct individual risk-benefit assessment and the performance of the nerve blocks using a combination of ultrasound guidance and peripheral nerve stimulation (dual guidance). The postoperative care of the patients requires trained staff.

Physician anaesthesia providers in Switzerland today and tomorrow: results of the National Anaesthesia Workforce Study (NAWOS).

AIMS OF THE STUDY: The Swiss healthcare system is highly ranked, given its unrestricted access to specialised care and short waiting lists for surgery. However, the need for anaesthetic and surgical care is escalating owing to the increasing size and ageing of the Swiss population. In addition, to address the persistent and recurrent SARS-CoV-2 pandemic crisis, the speciality of anaesthesia is under tremendous pressure to maintain an effective workforce in order to address population needs. The current number, characteristics and future evolution of the physician anaesthesia workforce in Switzerland are currently unknown. The purpose of this study was to assess the size and professional and sociodemographic characteristics of the current anaesthesia workforce in Switzerland and to forecast its development up to 2034. METHODS: We performed a cross-sectional study using a 150-item questionnaire prepared by the National Anaesthesia Workforce Study Group (NAWOS). We included all physicians (trainees and certified) practising anaesthesia in Switzerland. We collected demographic and professional information, such as the current position, hospital characteristics, workload, number of shifts and future life plans. We built a computer-based Markov model with Monte Carlo simulations to project both supply and demand for physician anaesthesia provider positions. RESULTS: Of the 2661 distributed questionnaires, 1985 (74.2%) were completed and returned. We found that the average age of anaesthesiologists practising in Switzerland was 45.2 years, with 44.3% of them being women and 76.9% holding a Swiss specialist title. Only 59.6% of respondents worked full time. The forecasting model showed a steady increase in the number of anaesthesiologists retiring by 2034, with 27% of full-time equivalent jobs being lost in the next 8 years. Even if existing full-time equivalent training positions are all filled, a gradual deficit of anaesthesiologists is to be expected after 2022, and the deficit should culminate in 2034 with a deficit ratio of 0.87. CONCLUSIONS: Due to the upcoming high retirement rate of anaesthesiologists, Switzerland is likely to face a shortage of anaesthesiologists in the near future. To compensate for the shortage, the country will likely increase its reliance on medical staff trained abroad. Southern and eastern cantons of Switzerland are particularly at risk, given that they already heavily rely on foreign anaesthesia workforce. This reliance should be considered a national priority because anaesthesiologists are heavily involved in both the treatment of patients with respiratory complications of SARS-CoV2 infection and the care of surgical patients, the number of which is expected to rise steadily in upcoming years.

What does local tenderness say about the origin of pain? An investigation of cervical zygapophysial joint pain.

BACKGROUND: Mechanical pain sensitivity is assessed in every patient with pain, either by palpation or by quantitative pressure algometry. Despite widespread use, no studies have formally addressed the usefulness of this practice for the identification of the source of pain. We tested the hypothesis that assessing mechanical pain sensitivity distinguishes damaged from healthy cervical zygapophysial (facet) joints. METHODS: Thirty-three patients with chronic unilateral neck pain were studied. Pressure pain thresholds (PPTs) were assessed bilaterally at all cervical zygapophysial joints. The diagnosis of zygapophysial joint pain was made by selective nerve blocks. Primary analysis was the comparison of the PPT between symptomatic and contralateral asymptomatic joints. The secondary end points were as follows: differences in PPT between affected and asymptomatic joints of the same side of patients with zygapophysial joint pain; differences in PPT at the painful side between patients with and without zygapophysial joint pain; and sensitivity and specificity of PPT for 2 different cutoffs (difference in PPT between affected and contralateral side by 1 and 30 kPa, meaning that the test was considered positive if the difference in PPT between painful and contralateral side was negative by at least 1 and 30 kPa, respectively). The PPT of patients was also compared with the PPT of 12 pain-free subjects. RESULTS: Zygapophysial joint pain was present in 14 patients. In these cases, the difference in mean PPT between affected and contralateral side (primary analysis) was -6.2 kPa (95% confidence interval: -19.5 to 7.2, P = 0.34). In addition, the secondary analyses yielded no statistically significant differences. For the cutoff of 1 kPa, sensitivity and specificity of PPT were 67% and 16%, respectively, resulting in a positive likelihood ratio of 0.79 and a diagnostic confidence of 38%. When the cutoff of 30 kPa was considered, the sensitivity decreased to only 13%, whereas the specificity increased to 95%, resulting in a positive likelihood ratio of 2.53 and a diagnostic confidence of 67%. The PPT was significantly lower in patients than in pain-free subjects (P < 0.001). CONCLUSIONS: Assessing mechanical pain sensitivity is not diagnostic for cervical zygapophysial joint pain. The finding should stimulate further research into a diagnostic tool that is widely used in the clinical examination of patients with pain.

Early Recognition of a Transient Ischemic Attack Utilizing Cerebral Oxygenation Monitoring During Shoulder Surgery in the Beach Chair Position: A Case Report.

Shoulder surgery in the beach chair position is routinely performed, and central neurological events are rare but potentially devastating. We present a patient with transient neurological deficits after a sudden blood pressure drop with a simultaneous decrease of regional cerebral saturation values registered by cerebral oximetry. We reviewed published cases and proposed possible strategies to prevent the occurrence of similar complications in this context.