Needle Advancement Research Articles

E-059 Guiding Sclerotherapy for Deep Lying Lesions using Advanced Angiographic Imaging Applications and MR-Fusion

BackgroundDeep head and neck lesions are challenging to treat using conventional guidance, such as ultrasound (US) and fluoroscopy. High impedance structures prevent the use of US, while fluoroscopy lacks resolution...

EUS‐guided 22‐gauge fine‐needle aspiration versus core biopsy needle in the evaluation of solid pancreatic neoplasms

Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is widely used for diagnosis of pancreatic lesions. The Echotip Procore Needle (Wilson-Cook Medical) is a new 22G fine biopsy needle (FNB) for obtaining core biopsy material at time of EUS. This study aimed to compare the technical and diagnostic performance of conventional FNA and FNB. Thirty-two patients met the design criteria for this prospective paired cohort study. All lesions sampled were solid (non-cystic) pancreatic masses by EUS appearance. Patients were randomized to receive FNA or FNB by first attempt. A cytopathologist performed on-site evaluations. Samples were assessed for accuracy of diagnosis, cellularity, contamination, and sufficiency for ancillary studies. Technical and diagnostic performances were compared. Compared to FNA, there was a statistically significant decreased ability of FNB to achieve a diagnosis (FNA 93.8%, FNB 28.1%, P < 0.001). FNB was diagnostically superior to FNA in 1 of 32 cases. Technical failures were observed in five cases due to resistance to advancement of the FNB needle. Regarding operator perceived ease-of-use, FNA outperformed FNB (P < 0.001). Eight cases had insufficient FNB material to survive tissue processing. There was no significant difference in mean specimen cellularity between devices. FNA samples showed an increased amount of contaminant (P = 0.036) but were more sufficient for ancillary studies (P = 0.502). Although deemed comparable to FNA when providing material for cytology, the pledged advantage of FNB acting like a core biopsy needle was not apparent in our series. Additional studies are needed before routine adoption of 22G FNB can be recommended.

Ultrasound for Routine Lumbar Puncture

The objective was to determine if use of ultrasound (US) by emergency physicians (EPs) to localize spinal landmarks improves the performance of lumbar puncture (LP). This was a prospective, randomized, controlled study conducted in a county teaching hospital. Subjects, adults 18years of age or older who were to receive LPs for routine clinical care in the emergency department (ED), were randomized either to undergo US localization of the puncture site or to have the puncture site determined by palpation of spinal landmarks. Primary outcomes were the number of needle insertion attempts and success of the procedure. Secondary outcomes were pain associated with the procedure, time to perform the procedure, number of traumatic taps, and patient satisfaction with the procedure. One-hundred patients were enrolled in the study, with 50 in each study group. There were no significant differences between the two groups in terms of age, sex, body mass index (BMI), indication for LP, or ease of palpation of landmarks. For both primary outcomes and secondary outcomes there were no significant differences between those undergoing US localization and those with palpation alone. These data do not suggest any advantage to the routine use of US localization for LP insertion, although further study may be warranted to look for benefit in the difficult to palpate or obese patient subgroups.

Investigation of an intelligent system for fiber optic-based epidural anesthesia.

Even though there have been many approaches to assist the anesthesiologists in performing regional anesthesia, none of the prior arts may be said as an unrestricted technique. The lack of a design that is with sufficient sensitivity to the targets of interest and automatic indication of needle placement makes it difficult to all-round implementation of field usage of objectiveness. In addition, light-weight easy-to-use realization is the key point of portability. This paper reports on an intelligent system of epidural space identification using optical technique, with particular emphasis on efficiency-enhanced aspects. Statistical algorithms, implemented in a dedicated field-programmable hardware platform along with an on-platform application-specific integrated chip, used to advance real-time self decision making in needle advancement are discussed together with the feedback results. Clinicians' viewpoint of improving the correct rate of our technique is explained in detail. Our study demonstrates not only that the improved system is able to behave as if it is a skillful anesthesiologist but also it has potential to bring promising assist into clinical use under varied conditions and small amount of sample, provided that several concerns are addressed.

Fluoroscopy Procedure and Equipment Changes to Reduce Staff Radiation Exposure in the Interventional Spine Suite

Background: Fluoroscopic guided percutaneous interventional spine procedures are increasingly performed in recent years as they have been shown to be target specific and enhance patient safety. However, ionizing radiation has been associated with stochastic effects such as cancer and genetic defects as well as deterministic effects such as cataracts, erythema, epilation, and even death. These are dose related, and hence, measures should be taken to minimize radiation exposure to patients and health care personnel to reduce these adverse effects. Objective: A risk reduction project was completed with the goal of reducing effective doses to the staff and patients in a university-based spinal interventional practice. Effective dose reduction to the staff and patients was hypothesized to occur with technique and equipment changes in the procedure suite. The goal of this study was to quantify effective dose rates to staff before and after interventions. Study Design: Retrospective study comparing descriptive data of effective dose to the health care staff before and after implementation of a combination of technique and equipment changes. Methods: Technique changes from pre to post intervention period included continuous needle advancement under continuous fluoroscopic controlled by the interventional physician to intermittent needle advancement under pulsed fluoroscopic controlled by the radiology technician. Equipment changes included circumferential lead drape skirt around the procedure table and use of mobile transparent lead barriers on both sides of the procedure table. Effective dose exposure measured in Millirem (mrem) from the radiation dosimetry badges for pre-intervention (February 2009 through June 2009) and post-intervention (November 2009 through March 2010) periods were examined through monthly radiation dosimetry reports for the fluoroscopy suite staff. Results: A total of 685 interventional procedures were performed in the pre-intervention period and 385 in the post-intervention period. The median cumulative mrem (interquartile range) for all staff combined in the pre-intervention period was 71 (28,75) and post-intervention period was 1 (0,3). The median mrem per procedure was significantly higher in the pre-intervention group 0.46 (0.36, 0.54) compared to post-intervention 0.01 (0.0.03); P &lt; 0.01. The percentage reduction in overall effective dose per procedure to all staff was 97.3%. Limitations: Observational study, multiple radiation reduction interventions confound the individual effects of each intervention’s effective dose Conclusions: Spinal injection technique and equipment changes in the procedure suite significantly reduced the rate of effective dose to the clinical staff. Key words: Fluoroscopy, effective radiation dose, spine

Randomized Trial of Conventional Transseptal Needle Versus Radiofrequency Energy Needle Puncture for Left Atrial Access (the TRAVERSE‐LA Study)

BackgroundTransseptal puncture is a critical step in achieving left atrial (LA) access for a variety of cardiac procedures. Although the mechanical Brockenbrough needle has historically been used for this procedure, a needle employing radiofrequency (RF) energy has more recently been approved for clinical use. We sought to investigate the comparative effectiveness of an RF versus conventional needle for transseptal LA access.Methods and ResultsIn this prospective, single‐blinded, controlled trial, 72 patients were randomized in a 1:1 fashion to an RF versus conventional (BRK‐1) transseptal needle. In an intention‐to‐treat analysis, the primary outcome was time required for transseptal LA access. Secondary outcomes included failure of the assigned needle, visible plastic dilator shavings from needle introduction, and any procedural complication. The median transseptal puncture time was 68% shorter using the RF needle compared with the conventional needle (2.3 minutes [interquartile range {IQR}, 1.7 to 3.8 minutes] versus 7.3 minutes [IQR, 2.7 to 14.1 minutes], P=0.005). Failure to achieve transseptal LA access with the assigned needle was less common using the RF versus conventional needle (0/36 [0%] versus 10/36 [27.8%], P<0.001). Plastic shavings were grossly visible after needle advancement through the dilator and sheath in 0 (0%) RF needle cases and 12 (33.3%) conventional needle cases (P<0.001). There were no differences in procedural complications (1/36 [2.8%] versus 1/36 [2.8%]).ConclusionsUse of an RF needle resulted in shorter time to transseptal LA access, less failure in achieving transseptal LA access, and fewer visible plastic shavings.Clinical Trial RegistrationURL: http://www.clinicaltrials.gov. Unique identifier: NCT01209260.

A Novel Phantom for Teaching and Learning Ultrasound-guided Needle Manipulation

Training in ultrasound-guided regional anesthesia can be acquired by attending peripheral nerve block courses. The most common novice error is “advancement of needle when tip was not visualized.” The use of simulation has shown improvement in the skill and success of ultrasound-guided procedures. Phantoms provide a simple tool that aid in the improvement of such skills. We describe a gelatin-based phantom that can be easily constructed and used to identify novice errors and facilitate in learning relevant skills. The phantom can be transilluminated to identify the target and is helpful in providing real-time, immediate feedback to novices as they practice probe–needle–target orientation.

Ultrasound-Guided Greater Occipital Nerve Blocks and Pulsed Radiofrequency Ablation for Diagnosis and Treatment of Occipital Neuralgia

Occipital neuralgia is a condition manifested by chronic occipital headaches and is thought to be caused by irritation or trauma to the greater occipital nerve (GON). Treatment for occipital neuralgia includes medications, nerve blocks, and pulsed radiofrequency ablation (PRFA). Landmark-guided GON blocks are the mainstay in both the diagnosis and treatment of occipital neuralgia. Ultrasound is being utilized more and more in the chronic pain clinic to guide needle advancement when performing procedures; however, there are no reports of ultrasound used to guide a diagnostic block or PRFA of the GON. We report two cases in which ultrasound was used to guide diagnostic greater occipital nerve blocks and greater occipital nerve pulsed radiofrequency ablation for treatment of occipital neuralgia. Two patients with occipital headaches are presented. In Case 1, ultrasound was used to guide diagnostic blocks of the greater occipital nerves. In Case 2, ultrasound was utilized to guide placement of radiofrequency probes for pulsed radiofrequency ablation of the greater occipital nerves. Both patients reported immediate, significant pain relief, with continued pain relief for several months. Further study is needed to examine any difference in outcomes or morbidity between the traditional landmark method versus ultrasound-guided blocks and pulsed radiofrequency ablation of the greater occipital nerves.

Factors influencing discomfort during anterior ultrasound-guided injection for hip arthrography

BackgroundAlthough ultrasound (US)-guided injection techniques for magnetic resonance arthrography of the hip have been used with increasing frequency to diagnose internal joint derangements, little is known about patient tolerance, which is relevant information for patients. The objective of this study was to evaluate prospectively the association between possible influencing factors and discomfort felt during the performance of anterior US-guided injection techniques targeting the femoral head–neck junction during hip arthrography. MethodsForty-four consecutive patients (21 women and 23 men; mean age, 41 years) undergoing magnetic resonance hip arthrography were sequentially assigned to receive injection alternating between fixed and freehand US-guided injection. Discomfort was assessed using a visual analog scale and relative ratings. Patient body mass index, extra-articular contrast leakage, the duration of the procedure, the needle advancement distance, and the fixed trajectory of the needle were assessed. Pearson’s correlation coefficients and multiple logistic regression analysis were used to determine the association. ResultsPuncture was successfully accomplished in all cases, and no relevant complications were reported. The only significant relationships were between discomfort and the time required for needle manipulation (r = 0.8) and fixed US-guided injection (r = 0.6; p < 0.001). Compared with the freehand technique, the fixed technique resulted in significantly less pain and took significantly less time to perform (p < 0.001). The procedure time during needle manipulation in the fixed US-guided injections (4.0 ± 0.9 seconds) was significantly less than that in the freehand US-guided injections (19.4 ± 17.6 seconds; p < 0.001). No significant relationships were found between discomfort and other parameters (r < 0.3, p > 0.05). ConclusionThe procedure time appears to be the most important factor influencing patient discomfort. Fixed US-guided injection is a time-saving technique that alleviates procedure-related discomfort.

Novice Learner In-Plane Ultrasound Imaging

Needle guidance under ultrasound is an acquired skill requiring fine motor control. Maintaining the image of an advancing needle in the plane of an ultrasound beam may be performed with the probe and needle orientated along the visual axis (AL) or across the visual axis (AC). This study was undertaken to determine if orientation affected task performance. Twenty-four relative novices were tasked to perform guided punctures to a target in a pork phantom using each technique 5 times. The technique first used was randomly chosen from a sealed envelope. The time taken to guide the needle to target and the accuracy of needle imaging were recorded. The mean time to locate the target was significantly faster for the AL technique, compared with the AC technique (group AL, 35.7, vs group AC, 58.6 seconds; P < 0.0001, Wilcoxon matched-pairs signed rank test). The mean imaging quality score was also significantly better when needle advancement was along the visual axis (group AL, 1.37, vs group AC, 1.64; P = 0.05). Advancing the needle along the visual axis was associated with improved task completion speed and quality of needle imaging. This ergonomic pattern, therefore, may be the more appropriate choice for novices learning ultrasound-guided in-plane needle imaging.

Local drug delivery to a human pancreatic tumor via a newly designed multiple injectable needle

Endoscopic ultrasound-guided fine needle injection (EUS-FNI) has been proposed as a novel technique for local delivery of antitumor agents to refractory tumors, including pancreatic cancer. However, the present outcome of this strategy remains insufficient, and further improvements as well as novel agents and injection devices are required. The aim of the study was to determine the feasibility of a newly designed 'multiple injectable needle' (MIN) for EUS-FNI and the resulting improvements in the drug distribution to the tumor in comparison with straight-type needles. Human pancreatic cancer BxPC-3 cells or orthotopic tumor were transplanted subcutaneously into athymic rats. Ethanol was injected into subcutaneous tumors using a MIN or straight-type needle. Sequential sections of subcutaneous tumors were stained with hematoxylin and eosin, and tumors and injury areas were quantified using ImageJ software. In the orthotopic tumors, injection of the outer needle of the MIN, advancement of the inner needle and ethanol infusion were monitored by EUS. Injury volume of subcutaneous tumors using a MIN was greater than that with the straight-type needles, except for large tumors. Injecting process using MIN was monitored with endoscopic ultrasound (EUS). This study showed improvement in the drug distribution in a tumor, following injection with MIN compared to straight-type needles, suggesting the novel device to be feasible for use in EUS-FNI.

Directable needle guide: efficacy for image-guided percutaneous interventions.

Diagnostic and therapeutic image-guided percutaneous interventions have become increasingly important in the clinical management of various conditions. Though precise needle placement via a safe route is essential for successful percutaneous interventions, it is often difficult in cases of deeply situated, small lesions. The present paper describes the efficacy of the directable needle guide (DNG), which allows manipulation of the direction of a fine needle within organs. The DNG was used in patients for needle biopsy of hepatic (n = 26) and splenic (n = 1) lesions and for percutaneous ethanol injection therapy for liver tumors (n = 33) under sonographic or computed tomography guidance. The DNG enabled the direction of a 21- or 22-gauge needle to be successfully changed during needle advancement in all cases, allowing adjustment of the location of the needle tip or needle access root to avoid vessels, the gallbladder, and the lungs. We conclude that DNG increases the safety and ease of percutaneous interventions.

Percutaneous Endoscopic Cecostomy (PEC) Tube Placement: A Case Series

Purpose: Percutaneous cecostomy (PEC) placement has been used to treat recurrent colonic pseudobstruction, colonic atony or obstipation in children since it was first described in the 1980s. However, its role in the adult patient population for similar indications or palliation has yet to be defined. There have only been a few published case reports of successful PEC placement in adults. We report our experience with PEC placement in two adult patients at our institution with colonic atony and dilated colons (Figure A). Methods: With the patient in the supine position, a site was identified in the ascending colon with external transillumination and corresponding indentation on endoscopy in the right lower quandrant. The abdominal wall was marked and prepped in a sterile manner. After a local anesthetic (1% lidocaine) was injected a 22 Gauge needle was advanced under endoscopic visualization into the colon lumen followed by advancement of the trocar needle directly adjacent to the 22 Gauge needle. A snare was introduced through the endoscope and opened in the colonic lumen. The guide wire was passed through the trocar and into the open snare (Figure B). The snare was closed around the guide wire. The endoscope and snare were removed, pulling the wire out through the anus. A skin incision was made at the site of needle insertion. The externally removable Kimberly Clark 20 Fr gastrostomy tube was lubricated and tied to the guide wire and subsequently pulled through the anus and into the colon. The trocar needle was removed, and the colostomy tube was pulled out from the colon through the skin. The external bumper was attached to the colostomy tube, and the tube was cut to remove the guide wire. The final position of the cecostomy tube was confirmed endoscopically (Figure C) and subsequently with an abdominal X-ray (Figure D). The tube was capped and sutured into place externally with 2 vicryl 2.0 sutures, and the tube site was cleaned and dressed. Results: In the cases described above, a colonoscopy was performed without difficulty and successful PEC placement was achieved using the modified PEG pull technique with relative ease. Our patients did well post procedure with complete resolution of their symptoms and were discharged with no active issues secondary to PEC placement. This illustrates how PEC tube placement can be used to safely manage adult patients with colonic atony in day to day practice. Conclusion: PEC is a potentially attractive alternative to surgical or fluoroscopic cecostomy placement. Further study in a prospective fashion needs to be performed to further outline its clinical indications, therapeutic possibilities, and potential complications.

Needle visibility in different tissue models for ultrasound‐guided regional anaesthesia

Models for ultrasound-guided regional anaesthesia (USGRA) are important for research and training. However, the limited data available show great differences in quality of needle and tissue visualisation with regard to the applied model. This study aims to compare common USGRA models and human tissue with regard to their influence on needle visibility. We conducted this study using four models (embalmed human cadaver, turkey breast, pork, and synthetic gel models) and a volunteer (human control) as well as two different needles [Stimuplex A (StA), conventional needle; Stimuplex D Plus (StD+), needle with improved echogenicity]. We obtained ultrasound videos of needle advancement and withdrawal using the in-plane approach at a 45° angle in all four models and the volunteer. Fifteen test persons were prospectively enrolled. Ultrasound videos were presented in a randomised, blinded manner. The test persons were asked to rate the visibility of the needle shaft (VS) and tip (VT) on a four-point scale (0-3). VS and VT were comparable between the human control and cadaver model for both needle types. The pork, turkey, and synthetic gel models had significantly higher visibility scores than the human control for both needle types. VS of StD+ was significantly higher than that of StA in the pork and turkey models, but not in the synthetic model, cadaver model, or human control. In this pilot study, needle visibility in embalmed cadaver is comparable with that in human control. Needle visibility was significantly higher in other tissue models (turkey breast, pork, synthetic gel models) than in the human control, which may limit their value in training environments.

Application technique: placement of a prostate–rectum spacer in men undergoing prostate radiation therapy

What's known on the subject? and What does the study add? Different spacing agents have been tested to reduce incidential radiation exposure of the rectum during radiotherapy to the prostate. These agents all had certain drawbacks; either the created space was too small or the agents used did not stay in place during radiotherapy treatment. The study describes the transperineal injection technique of a spacing agent in detail. Furthermore it shows the safety and efficacy of the spacing hydrogel used and shows that it overcomes some of the drawbacks of the previously examined spacing agents. • To describe the technique used to apply a hydrogel spacer between the prostate and rectum so as to decrease the radiation dose to the rectum in patients with prostate cancer who are undergoing radiotherapy. • A prospective study evaluating the safety and efficacy of prostate-rectum spacer injection was conducted in 29 male patients with prostate cancer scheduled for radiotherapy. • Spacing hydrogel was injected into the perirectal space using a transperineal approach under real-time transrectal ultrasonography guidance. • With the needle tip positioned beyond the rectourethralis muscle, saline injection opened the space between Denonvilliers' fascia and the anterior rectal wall, allowing needle advancement to the mid-prostate without rectal wall injury. Injection of hydrogel precursors further opened this space, which was then maintained as a result of hydrogel polymerization. • Procedure duration and adverse events were monitored. Computed tomography and/or magnetic resonance imaging simulation scans were performed before and after injection. The hydrogel-created space was measured and the reduction in percent volume of the rectum receiving at least 70 Gy (rectal V70) was determined. • Hydrogel injection resulted in mean (sd) additional prostate-rectum space relative to baseline of 9.87 (5.92) mm. • The mean (sd) procedure time, as measured by needle insertion and removal, was 6.3 (3.2) min. • The relative reduction in rectal V70 was 60.6%. • There were no unanticipated adverse events associated with the hydrogel procedure or the hydrogel. • Hydrogel spacer injection using hydrodissection is a fast and effective procedure to separate the rectal wall from the prostate in order to avoid rectal toxicity. • Hydrogel spacer injection resulted in the addition of ∼1 cm of space • Computed incidental radiation exposure, the rectal V70, was substantially reduced.

Symptomatic Postlaminectomy Cerebrospinal Fluid Leak Treated With 4-Dimensional Ultrasound-guided Epidural Blood Patch

A persistent cerebrospinal fluid leak after spinal surgery can be associated with both meningitis and/or pneumocephalus. Therefore, early active intervention is recommended with surgical exploration, lumbar subarachnoid drain, and less commonly epidural blood patch. In the absence of a ligamentum flavum, the use of high-resolution ultrasound (US) spine imaging enables real-time advancement of a Tuohy needle towards the dura and the precise injection of blood to cover the dural defect. Six patients, after lumbar spine surgery with instrumentation and primary closure was complicated by incidental dural tears, developed severe symptomatic headaches that failed conservative therapy. All patients underwent US-guided epidural blood patch. Precise needle advancement to the dura was observed with US guidance, and 4-dimensional US scanning was used to confirm the expansion of blood over the dura in real time. All patients had symptomatic relief of their headaches and successful treatment of dural leaks using US-guided blood patch. Real-time US guidance allowed accurate positioning of the Tuohy needle and deposition of the epidural blood patch in the setting of a surgically removed ligamentum flavum. Further investigations are needed to confirm that an US-guided epidural blood patch may offer reliable symptomatic relief to postsurgical persistent cerebrospinal fluid leak and may serve as an intermediate step along a spectrum between conservative initial management and surgical reexploration.

Patient's assessment of discomfort during ultrasound‐guided injection of Morton's neuroma: Selecting the optimal approach

Assess patient discomfort during two different methods of injection of Morton's neuroma. Sixty-eight patients referred for ultrasound-guided injection of Morton's neuroma had punctures performed dorsal or plantar to the interdigital skin crease, with and without preliminary subcutaneous local anesthesia (LA). Patients rated discomfort during skin puncture (SP) and needle advancement (NA) using a visual analog scale. Average pain score was 4.4 ± 2.3 (1 SD) for the plantar approach and 2.9 ± 2.0 for the dorsal approach. This difference was statistically significant during SP (p < 0.01) and NA (p < 0.05). During the plantar approach with LA, mean pain score during SP was 4.4 (± 2.1) and 3.9 (± 2.8) during NA. This plantar approach without LA resulted in a pain score of 4.3 (± 2.6) and 3.8 (± 3.1), respectively. Mean pain scores for patients injected from the dorsal approach with LA during SP were 3.8 (± 2.7) and NA were 2.2 (± 2.0) and without LA were 2.6 (± 1.9) and 3.0 (± 2.1). There was no statistical significance in mean pain score difference during SP and NA, with and without LA for either the plantar (p > 0.05) or the dorsal (p > 0.05) approach. Injection of Morton's neuroma was better tolerated via a dorsal approach and use of preliminary LA did not confer any benefit.

Novice performance of ultrasound‐guided needle advancement: standard 38‐mm transducer vs 25‐mm hockey stick transducer*

The optimal method to develop expertise in ultrasound-guided regional anaesthesia is unknown. Studies of laryngoscopic expertise in novices demonstrate that the choice of laryngoscope affects performance. In this study, we aimed to compare the effect of two different linear array transducers (38-mm standard vs 25-mm hockey stick) on novice performance of ultrasound-guided needle advancement. Following randomisation, participants watched a video model of expert performance of ultrasound-guided needle advancement. Recruits performed the modelled task on a turkey breast model. The median (IQR [range]) composite error score was statistically significantly larger for participants in the hockey stick transducer group compared with the standard transducer group; 10.0 (7.3-14.3 [2.5-29.0]) vs 7.5 (4.5-10.0 [2.0-28.0]) respectively, (p = 0.01). This study has demonstrated that performance of ultrasound-guided needle advancement by novice operators after simple video instruction is better (as assessed using a composite error score) with a standard 38-mm transducer than with a 25-mm hockey stick transducer.

CT Guided Bone Marrow Aspiration and Core Biopsy

Hemorrhagic complications related to bone marrow aspiration and trephine biopsy are uncommon. Risk factors include thrombocytopenia, myeloproliferative disorders, concurrent use of anticoagulants, and obesity. Here we describe our technique for bone marrow aspiration and biopsy of the posterior iliac crest using CT guidance. Our technique ensures needle passage only through subcutaneous fat and bone, avoiding muscle and neurovascular structures, as well as controlled and precise needle advancement within bone. This technique should be considered for use in patients that are at increased risk for procedure related complications, particularly obese patients, where surface anatomical landmarks may prove unreliable.

Forced Needle Advancement During Needle-Nerve Contact in a Porcine Model

In this study, we determined whether needle advancement during needle-nerve contact (forced needle-nerve contact) is associated with a higher risk of nerve injury compared with needle-nerve contact without needle advancement (nonforced needle-nerve contact). In 8 anesthetized pigs, the brachial plexus nerves underwent forced (0.15 Newton) or nonforced (0.0 Newton) needle-nerve contact without nerve penetration. The grade of nerve injury was histologically assessed using an objective score ranging from 0 (no injury) to 4 (severe injury). Sixty-nine nerves, including controls, were examined. Histology revealed a significant difference between forced and nonforced needle-nerve contact (median [interquartile range] 3 [2-4] vs 2 [1-2]; P = 0.004). Myelin damage and intraneural hematoma occurred only after forced needle-nerve contact. The severity of structural nerve injury after needle-nerve contact was directly related to force exposure via needle advancement.