Electrical impedance to detect accidental nerve puncture during ultrasound-guided peripheral nerve blocks

Purpose

The objective of this study was to assess if an increase in electrical impedance was associated with intraneural (sub-epineural) needle tip placement.

Methods

Two electrical impedance measurements were carried out in each of 140 peripheral nerve blocks. The first measurement was performed at a distance of 0.5-1 cm from the nerve trunk (reference value), and the second measurement was performed close to the nerve, either immediately before local anesthetic injection if no nerve puncture was suspected, or immediately before repositioning the needle if nerve puncture was suspected. Nerve puncture was suspected if any one of the following indications was present: pain or paresthesia; motor responses with a minimal stimulating current < 0.4 mA; needle tip observed inside the nerve using ultrasound; nerve swelling after injection of local anesthetic. Electrical impedance variations were compared between the no puncture and the suspected puncture groups.

Results

Nerve puncture was suspected in 21 cases. The median variation [quartiles] of electrical impedance was +6.6% [?20; 36%] in the suspected puncture group (n = 21) and ?10.0% [?28; 0%] in the no puncture group (n = 119) (P = 0.02). Absolute values of electrical impedance close to the nerve were greater in the suspected puncture group (15.5 kΩ [12.0; 18.0 kΩ]) vs the no puncture group (12.0 kΩ [8.9; 15.1% kΩ]) (P = 0.013). A receiver operating characteristic (ROC) curve was constructed, and the optimal cut-off for impedance was +4.3%.

Conclusion

A > 4.3% increase in electrical impedance may indicate accidental nerve puncture during peripheral nerve block.     

Steuerung der axillären Multiinjektionstechnik zur Plexusanästhesie

Background

Ultrasound guidance is still a young method in regional anesthesia when compared to nerve stimulation and only a few studies exist comparing these two techniques in an axillary multiple injection approach.

Aim

This prospective, randomized, observer-blinded study compared an ultrasound-guided (SONO) quadruple injection axillary block (out of plane, perineural) with a nerve stimulation-guided (STIM) triple injection axillary block for upper limb surgery.

Material and methods

A total of 60 patients were randomized to either the SONO (n?=?30) or STIM (n?=?30) group. For the block 40–50 ml mepivacaine 1.5?% (plexus) and 5–10 ml mepivacaine 0.5?% (subcutaneous in the medial skin of the arm) was used. Anesthesia time was recorded as the primary end point. After evaluation of block-related pain using a visual analog scale (VAS) a blinded observer tested sensory and motor function of the median nerve (MED), ulnar nerve (ULN), radial nerve (RAD), musculocutaneous nerve of the upper limb (MUC) and medial cutaneous nerve of the forearm (CAM) at defined times. The main outcome variable was onset time (defined loss of sensory/motor function).

Results

No differences were observed between the groups in terms of onset time (single nerves 10–20 min, plexus 20–25 min) and success rate (SONO 90?%, STIM 89?%). Patient satisfaction as measured by block-related pain score (VAS 2 cm), complications (vascular puncture SONO 7?%, STIM 11?%; paresthesia SONO 21?%, STIM 22?%) and patient acceptance (SONO 92?%, STIM 91?%) showed no differences. Performance time was shorter in the SONO group (6.68?±?1.72 min vs. 8.05?±?2.58, p?=?0.02).

Conclusion

Nerve stimulation-guided axillary plexus blocks performed by trained anesthesiologists may result in similar onset times and success rates compared to ultrasound-guided blocks.     

Ultrasound-guided sciatic nerve block: a comparison between four different infragluteal probe and needle alignment approaches

Purpose

Our aim was compare onset time of sciatic nerve blockade (SNB) performed distal to the subgluteal fold using four different ultrasound (US)-guided approaches in patients undergoing foot or ankle surgery.

Methods

Patients were assigned to one of four groups: SI patients received SNB using short-axis (SA) view of the SN and in-plane (IP) placement of block needle (SA-IP approach); LI patients received SNB using long-axis (LA) view of the SN and IP needle placement (LA-IP approach); SO patients received the block using SA view of the SN and out-of-plane (OP) needle placement (SA-OP approach); LO patients received SNB using LA view of the SN and OP needle placement (LA-OP). Primary outcome included onset time of sensory and motor SNB. Patient satisfaction concerning the postoperative analgesia was noted.

Results

The LI group had significantly faster onset of sensory blockade on the distribution of tibial nerve (16.0 ± 5.6 vs. 23.5 ± 3.6) and common peroneal nerve (12.5 ± 4.3 vs. 19.1 ± 5.4 min) in comparison with the LO group. The LI group had significantly faster onset of motor blockade on the distribution of tibial nerve (21.1 ± 6.2 vs. 26 ± 3.1) and common peroneal nerve (17.7 ± 4.8 vs. 23.7 ± 5.8 min.) in comparison with the LO group. The LI group had the highest rate of patient satisfaction for postoperative analgesia and the LO group had the lowest.

Conclusion

The LA-IP approach resulted in a rapid onset of SNB and was associated with the best satisfaction for postoperative analgesia in comparison with LA-OP, SA-IP, and SA-OP approaches for patients undergoing foot and ankle surgery.     

Ultrasound-guided suprascapular nerve block: a correlation with fluoroscopic and cadaveric findings

Purpose

Previous work on the ultrasound-guided injection technique and the sonoanatomy of the suprascapular region relevant to the suprascapular nerve (SSN) block suggested that the ultrasound scan showed the presence of the suprascapular notch and transverse ligament. The intended target of the ultrasound-guided injection was the notch. The objective of this case report and the subsequent cadaver dissection findings is to reassess the interpretation of the ultrasound images when locating structures for SSN block.

Clinical features

A 45-yr-old man with chronic shoulder pain received an ultrasound-guided SSN block using the suprascapular notch as the intended target. The position of the needle was verified by fluoroscopy, which showed the tip of the needle well outside the suprascapular notch. Similar ultrasound-guided SSN blocks were performed in two cadavers. Dissections were performed which showed that the needle tips were not at the suprascapular notch but, more accurately, were close to the SSN but at the floor of the suprascapular fossa between the suprascapular and spinoglenoid notch.

Conclusion

Our fluoroscopic and cadaver dissection findings both suggest that the ultrasound image of the SSN block shown by the well-described technique is actually targeting the nerve on the floor of the suprascapular spine between the suprascapular and spinoglenoid notches rather than the suprascapular notch itself. The structure previously identified as the transverse ligament is actually the fascia layer of the supraspinatus muscle.     

Ultrasound-guided block of the brachial plexus at the humeral canal

Purpose

Conduction block of the brachial plexus block at the humeral canal, as described by Dupre, has certain clinical indications. The aim of this preliminary study was to assess the feasibility of this technique under ultrasound guidance.

Methods

After ultrasound evaluation of the brachial plexus at the humeral canal in 61 adult volunteers, we performed ultrasound-guided blocks in another 20 adult patients. A linear 38 mm probe, 13–6 MHz, and a 50-mm insulated block needle were used to guide injection of lidocaine 1.5% with epinephrine.

Results

Ulnar and median nerves are superficial and located at similar depths. Ultrasound imaging showed the musculocutaneous nerve to be located dorsally. The radial nerve is dorsal to the plane of the musculocutaneous nerve. Relative to the brachial artery, the median nerve is situated between 12 and 1 o’clock in 66% of the cases. Relative to the basilic vein, the ulnar nerve is situated at 3 o’clock in 46% of the cases. The evaluated block sequence was radial, ulnar, musculocutaneous and median nerve; two points of puncture were mandatory, and 6.85 ± 0.37 min were required to perform the blocks. Sensory onset times were similar for the four nerves. Injectate volume was lower for the musculocutaneous nerve compared to other nerves (P < 0.05). All 20 patients experienced complete sensory and motor blocks.

Conclusion

We describe an approach to, and the feasibility of ultrasound-guided block of the brachial plexus at the humeral canal. Further study will be required to establish the effectiveness and the safety of this technique.     

The role of electrical stimulation in ultrasound-guided subgluteal sciatic nerve block: a retrospective study on how response pattern and minimal evoked current affect the resultant blockade

Purpose

Nerve stimulation may be combined with ultrasound imaging for a block of deeply located nerves such as the sciatic nerve in the subgluteal region. At present, it is unknown how the use of nerve stimulation affects blockade after this nerve block. We retrospectively compared the effects of the two types of motor response and those of minimal evoked current above and below 0.5 mA on ultrasound-guided subgluteal sciatic nerve block using mepivacaine or ropivacaine, two local anesthetics with different onset time and duration.

Methods

We reviewed records and video images of patients who, from April 2008 until October 2011, received ultrasound-guided subgluteal sciatic nerve block combined with nerve stimulation using 20 ml of either 1.5 % mepivacaine with 1:400,000 epinephrine or 0.5 % ropivacaine. Sensory and motor blockade data for 30 min after the block and for the duration of the blockade were gathered. Patients for whom any data were missing, the video image was poor, and/or intraneural injection was observed during the block were excluded from the study. The same data were compared in two ways: regarding the motor response pattern between the response of the tibial nerve and the common peroneal nerve, and regarding the minimal current between low current (< 0.5 mA) and high current (≥0.5 mA). The primary endpoints were the onset and duration of blockade of the sciatic nerve block.

Results

We analyzed the data of 170 and 99 patients who received mepivacaine and ropivacaine, respectively. The progress of sensory and motor blockade as well as block duration was similar between different motor response patterns after both anesthetics. The proportion of patients who developed sensory block of the tibial nerve and motor block at 30 min was higher in the low minimal current group than in the other group receiving mepivacaine. Patients in the former group also had longer block duration. With ropivacaine, complete motor blockade was present at 30 min in a higher proportion of patients after lower minimal evoked current than after higher minimal evoked current.

Conclusion

When ultrasound-guided subgluteal sciatic nerve block was conducted with nerve stimulation, the motor response pattern did not markedly affect the progress of sensory or motor blockade or block duration. Lower minimal evoked current was associated with faster onset in sensory and motor block and longer block duration after mepivacaine and faster onset in motor block after ropivacaine. The clinical significance of this, however, has yet to be determined.     

Distale Blockaden des N. ischiadicus

Background and objectives

The design of this study is related to an important current issue: should local anesthetics be intentionally injected into peripheral nerves? Answering this question is not possible without better knowledge regarding classical methods of nerve localization (e.g. cause of paresthesias and nerve stimulation technique). Have intraneural injections ever been avoided? This prospective, randomized comparison of distal sciatic nerve block with ultrasound guidance tested the hypothesis that intraneural injection of local anesthetics using the nerve stimulation technique is common and associated with a higher success rate.

Material and methods

In this study 250 adult patients were randomly allocated either to the nerve stimulation group (group NS, n?=?125) or to the ultrasound guidance group (group US, n?=?125). The sciatic nerve was anesthetized with 20 ml prilocaine 1% and 10 ml ropivacaine 0.75%. In the US group the goal was an intraepineural needle position. In the NS group progress of the block was observed by a second physician using ultrasound imaging but blinded for the investigator performing the nerve stimulation. The main outcome variables were time until readiness for surgery (performance time and onset time), success rate and frequency of paresthesias. In the NS group needle positions and corresponding stimulation thresholds were recorded.

Results

In both groups seven patients were excluded from further analysis because of protocol violation. In the NS group (n?=?118) the following needle positions were estimated: intraepineural (NS 1, n?=?51), extraparaneural (NS 2, n?=?33), needle tip dislocation from intraepineural to extraparaneural while injecting local anesthetic (NS 3, n?=?19) and other or not determined needle positions (n?=?15). Paresthesias indicated an intraneural needle position with an odds ratio of 27.4 (specificity 98.8%, sensitivity 45.9%). The success rate without supplementation was significantly higher in the US group (94.9% vs. 61.9%, p?<?0.001) and the time until readiness for surgery was significantly (p?<?0.001) shorter for successful blocks: 15.1 min (95% confidence interval CI 13.6–16.5 min) vs. 28 min (95% CI 24.9–31.1 min). In the NS subgroups the results were as follows (95% CI in brackets): NS1 88.2% and 22.7 min (19.5–25.9 min), NS2 24.2% and 43.3 min (35.5–51.1 min) and NS3 36.8% and 35.3 min (22.1–48.4 min).

Conclusions

For distal sciatic nerve blocks using the nerve stimulation technique, intraepineural injection of local anesthetics is common and associated with significant and clinically important higher success rates as well as shorter times until readiness for surgery. In both groups no block-related nerve damage was observed. The results indicate that for some blocks (e.g. sciatic, supraclavicular) perforation of the outer layers of connective tissue was always an important prerequisite for success using classical methods of nerve localization (cause of paresthesias and nerve stimulation technique). Additional nerve stimulation with an ultrasound-guided distal sciatic nerve block cannot make any additional contribution to the safety or success of the block. New insights concerning the architecture of the sciatic nerve are discussed and associated implications for the performance of distal ultrasound-guided sciatic nerve block are addressed.     

Electrophysiological stimulation (Tsui test) is feasible for epidural catheter positioning in adults with chronic back pain: a cohort study

Purpose

Determining epidural catheter placement and accurately depositing corticosteroids at the site of the pathology in adults with chronic back pain can be challenging. Fluoroscopy is considered the standard of care for guiding epidural catheter positioning and subsequent injection in patients receiving epidural corticosteroids, but the technique has some limitations. We hypothesized that electrophysiological stimulation using the Tsui test is feasible for determining the appropriate epidural catheter position in adults with chronic back pain receiving epidural corticosteroids.

Methods

We conducted a prospective cohort study of 12 patients receiving epidural corticosteroid injections for chronic back pain. Anatomical landmarks and epidural needle positions were initially confirmed by fluoroscopy. Epidural catheter position was assessed according to sensory and motor responses, as described by Tsui et al. (Can J Anaesth 45: 640-644, 1998). The current was increased slowly from zero until muscle activity was visible or the current reached 10 mA. The catheter was then advanced until muscle responses occurred in the desired myotome. The test was deemed positive or negative according to the Tsui criteria. The anatomical level was confirmed by fluoroscopy prior to injection.

Results

Electrophysiological stimulation effectively established the appropriate epidural catheter position in 11 patients (92%). Epidural stimulation occurred at a mean (SD) threshold of 3.95 (3.35) mA. The kappa statistic between interventions was 0.65, indicating a substantial level of agreement.

Conclusion

This study demonstrated that electrophysiological stimulation using the Tsui technique is feasible for epidural catheter positioning in adults with chronic back pain. It may optimize epidural steroid injection in this population.     

Magnesium added to bupivacaine prolongs the duration of analgesia after interscalene nerve block

Purpose

Local anesthetic adjuvants have been studied previously in an attempt to prolong the duration of analgesia after peripheral nerve blockade. Magnesium has been shown to have an antinociceptive effect in animal and human pain models. We evaluated the effects of adding magnesium sulphate to long-acting local anesthetics for interscalene nerve block to prolong the duration of analgesia and improve the analgesic quality.

Methods

We enrolled 66 patients undergoing arthroscopic rotator cuff repair. The interscalene nerve block was performed with 0.5% bupivacaine 20?mL with epinephrine (1:200,000) plus either 10% magnesium sulphate 2?mL (Magnesium Group) or normal saline 2?mL (Saline Group). The following data were recorded for 24 hr after surgery: onset times and durations of sensory and motor blocks, analgesic duration, the pain numeric rating scale (NRS), postoperative fentanyl consumption, and complications.

Results

The duration of analgesia was longer in the Magnesium Group than in the Saline Group [mean and (standard deviation) 664 (188) min vs 553 (155) min, respectively; P?=?0.017]. Patients in the Magnesium Group had significantly reduced pain NRS scores at 12 hr (P?=?0.012), but the cumulative fentanyl consumption was similar in both groups. The onset times and durations of sensory and motor blocks were not significantly different between the two groups.

Conclusion

The addition of magnesium sulphate to a bupivacaine-epinephrine mixture for interscalene nerve block prolongs the duration of analgesia and reduces postoperative pain.     

Age delays the recovery of distal motor latency after carpal tunnel syndrome surgery

Background

Studies have shown slow healing of peripheral nerve injury in elderly patients. Carpal tunnel syndrome (CTS) is the most frequent compressive mononeuropathy, affecting mostly older people and females. Few studies have assessed electrophysiological differences between younger and older patients. We aimed to evaluate age-dependent differences in electrophysiological parameters preoperatively and postoperatively over a 100-day postoperative period.

Method

This retrospective study included 258 hands of patients who underwent conventional open-technique carpal tunnel syndrome surgery. Patients with paresthesia in the median nerve distribution or with impaired sensation or abnormal findings in sensory and motor median nerve conduction studies were enrolled. The age dependence of the preoperative values of distal motor latency, amplitude of the compound motor action potential and sensory conduction velocity was estimated using regression analysis.

Results

Statistically significant age dependence was found for the preoperative distal motor latency, compound motor action potential, amplitude and sensory conduction velocity. The repair of segmental demyelination was nearly twice as slow in the older group, at a 5 % significance level, even when comparing groups with the same preoperative distal motor latency.

Conclusions

Analysis of preoperative nerve conduction parameters indicates that surgery for carpal tunnel syndrome is performed later in older patients.     

Perivascular brachial plexus block. Ultrasound versus nerve stimulator

Background

Optimizing the needle position using ultrasound (US) instead of electrical nerve stimulation (NSt) is increasingly common for perivascular brachial plexus block. These two methods were compared in a prospective, randomized, single-blinded controlled trial regarding effectiveness and time of onset of peripheral nerve blockade.

Methods

After puncture (penetration of neurovascular sheath and complete insertion of needle) 56 patients were randomly assigned to either the US group (finding the needle tip in transpectoral section, short axis, correction of needle position if local anesthetic spread was insufficient) or the NSt group (target impulse reaction in median, ulnar or radial nerve of 0.3?mA/0.1?ms, if necessary correction of position before injection of local anesthetic) to verify the needle position. All patients received 500?mg 1% mepivacaine. Sensory and motor blocks were tested by single nerve measurements (SNM) 5, 10 and 20?min after finishing the injection, where 0 represents minimal and 2 maximal success of the block.

Results

Single nerve measurements were analyzed using repeated measures ANOVA. The mean results of cumulative SNMs were significantly higher in the US group at all measurement times. Sensitivity US/NSt: 5?min: 3.36±2.32/2.63±1.87; 10?min: 5.45±2.41/4.21±2.45; 20?min: 7.30±2.02/6.43±2.43, p=0.015, motor function US/NSt: 5?min: 3.91±1.81/3.02±1.67; 10?min: 5.27±1.66/4.05±1.70; 20?min: 6.64±1.37/5.50±1.90, p<0.001. At the beginning of surgery complete nerve blockade was achieved in 89% in the US group and 68% in the NSt group (p=0.006), 3 (US) versus 7 (NSt) patients needed supplementation and 3 (US) versus 11 (NSt) patients needed general anesthesia (p=0.022). To achieve the nerve block took approximately 1?min more in the US group (p=0.003).

Conclusion

The use of ultrasound in perivascular brachial plexus blocks leads to significantly higher success rates and shorter times of onset.     

A Clinical Pathway for Total Shoulder Arthroplasty—A Pilot Study

Background

Appropriate pain management after total shoulder arthroplasty (TSA) facilitates rehabilitation and may improve clinical outcomes.

Questions/purposes

This prospective, observational study evaluated a multimodal analgesia clinical pathway for TSA.

Methods

Ten TSA patients received an interscalene nerve block (25 cm³ 0.375% ropivacaine) with intraoperative general anesthesia. Postoperative analgesia included regularly scheduled non-opioid analgesics (meloxicam, acetaminophen, and pregabalin) and opioids on demand (oral oxycodone and intravenous patient-controlled hydromorphone). Patients were evaluated twice daily to assess pain, anterior deltoid strength, handgrip strength, and sensory function.

Results

The nerve block lasted an average of 18 h. Patients had minimal pain after surgery; 0 (median score on a 0–10 scale) in the Post-Anesthesia Care Unit (PACU) but increased on postoperative day (POD) 1 to 2.3 (0.0, 3.8; median (25%, 75%)) at rest and 3.8 (2.1, 6.1) with movement. Half of the patients activated the patient-controlled analgesia four or fewer times in the first 24 h after surgery. Operative anterior deltoid strength was 0 in the PACU but returned to 68% by POD 1. Operative hand strength was 0 (median) in the PACU, but the third quartile (75%) had normalized strength 49% of preoperative value.

Conclusions

Patients did well with this multimodal analgesic protocol. Pain scores were low, half of the patients used little or no intravenous opiate, and some patients had good handgrip strength. Future research can focus on increasing duration of analgesia from the nerve block, minimizing motor block, lowering pain scores, and avoiding intravenous opioids.     

Three lateral osteotomy designs for bilateral sagittal split osteotomy: biomechanical evaluation with three-dimensional finite element analysis

Background

Quantitative sensory testing (QST) is applied to evaluate somatosensory nerve fiber function in the spinal system. This study uses QST in patients with sensory dysfunctions after oral and maxillofacial surgery.

Methods

Orofacial sensory functions were investigated by psychophysical means in 60 volunteers (30 patients with sensory disturbances and 30 control subjects) in innervation areas of the infraorbital, mental and lingual nerves. The patients were tested 1 week, 4 weeks, 7 weeks and 10 weeks following oral and maxillofacial surgery.

Results

QST monitored somatosensory deficits and recovery of trigeminal nerve functions in all patients. Significant differences (p < 0.05) between control group and patients were shown for cold, warm and mechanical detection thresholds and for cold, heat and mechanical pain thresholds. Additionally, QST monitored recovery of nerve functions in all patients.

Conclusion

QST can be applied for non-invasive assessment of sensory nerve function (Aβ-, Aδ- and C-fiber) in the orofacial region and is useful in the diagnosis of trigeminal nerve disorders in patients.     

Tumors and tumor-like lesions mimicking carpal tunnel syndrome

Introduction

Tumors and tumor-like lesions in or around the median nerve are uncommon causes of carpal tunnel syndrome (CTS). The purpose of the present study is to highlight the diagnostic approach and point out the profile of patients with CTS and potential underlying pathology.

Materials and methods

Twenty-eight patients with 32 affected hands had CTS correlated to a mass in or around the nerve. In 20 hands a palpable mass was present. Diagnostic workup included nerve conduction studies, ultrasound and/or MRI. Pre- and postoperative examination included two-point discrimination (2PD), grip strength, visual analogue scale (for pain) (VAS) and disabilities of the arm, shoulder and hand (DASH) scores.

Results

Twelve of 28 patients were young (range 9–38 years) and 10 were male. Nerve compression was due to 27 extraneural lesions (8 abnormal muscles, 5 lipomas, 7 tenosynovitis, 4 vascular tumors, 2 ganglia, 1 Dupuytren’s fibromatosis) and five intraneural tumors (three schwannomas, one neurofibroma, one sarcoma). Nerve decompression and excision of extraneural lesions were performed in all cases whereas in intraneural tumors, decompression was followed by excision in most cases and nerve grafting in one. Mean follow-up was 22 months (12–105 months). Extraneural masses were associated with a better outcome than nerve tumors. The mean postoperative VAS/DASH scores were 0.3/16.2 in extraneural lesions and 2.5/22 in intraneural lesions. The 2PD improved gradually in all patients (mean pre- and postoperative 12 and 5 mm). The mean grip strength increased from 28 to 31.3 kg postoperatively.

Conclusions

Although rare, the surgeon should include in the differential diagnosis of CTS the unusual cause of tumors and tumor-like lesions, especially when the patients’ profile is not typical (young, male, no repetitive stress or manual labor). In addition, the presence of a palpable mass at the distal forearm or palm dictates the need for imaging studies. The extent, location and aggressiveness of the mass will determine the approach and type of procedure.     

Preservation Versus Division of Ilioinguinal Nerve on Open Mesh Repair of Inguinal Hernia: A Meta-analysis of Randomized Controlled Trials

Background

Chronic groin pain after inguinal hernia repair, a serious problem, is caused by entrapment of the ilioinguinal nerve either by mesh or development of fibrosis. Division of the ilioinguinal nerve during hernioplasty has been found to reduce the incidence of chronic groin pain. However, the traditional approach favors preservation of the ilioinguinal nerve during open hernia repair.

Methods

We conducted a systematic review and meta-analysis of randomized controlled trials that compared the outcomes of preservation versus division of the ilioinguinal nerve during open mesh repair of inguinal hernia. The primary outcome was the incidence of groin pain; secondary outcomes were numbness and sensory loss.

Results

We reviewed six trials with 1,286 patients. We found no difference between the groups for the incidence of groin pain or numbness at 1, 6, and 12 months after open mesh inguinal repair. The incidence of sensory loss or change was significantly higher in the division group than in the preservation group at 6 months [risk ratio (RR) 1.25; 95?% confidence interval (CI) 1.02–1.53] and at 12 months (RR 1.55; 95?% CI 1.01–2.37) postoperatively. No significant differences between the groups were noted at any other points in time.

Conclusions

Preservation of the ilioinguinal nerve during open mesh repair of inguinal hernia is associated with a decreased incidence of sensory loss at 6 and 12 months postoperatively compared with that of the division technique. No significant differences were found between the groups for chronic groin pain or numbness.     

Ultrasound-guided perineural steroid injection to treat intractable pain due to sciatic nerve injury

Purpose

Sciatic neuropathy is a rare but serious complication of cardiac surgery. Neuropathic pain following nerve injury can be severely debilitating and largely resistant to treatment. We present a case of this complication where ultrasound-guided perineural steroid injection at the site of the sciatic nerve injury provided excellent pain relief and facilitated subsequent rehabilitation.

Clinical features

A 17-yr-old boy developed bilateral sciatic neuropathy after a nine-hour cardiac surgical procedure in the supine position, resulting in debilitating dysesthesia refractory to neuropathic pain therapies and leading to severe functional limitation. With magnetic resonance imaging of the lower extremities, the location of the lesion was determined to be from the level of the superior gemellus to the level of the quadratus femoris. An ultrasound-guided injection of triamcinolone 20 mg and lidocaine 40 mg around both sciatic nerves at the level of the lesion was administered two months after the surgery, and the pain score (rated on a scale 0-10) at rest decreased from 9-10 to 1 two weeks after the injection.

Conclusions

There are a limited number of reports in the literature on sciatic nerve injuries associated with cardiac surgery. This case illustrates the efficacy of ultrasound-guided steroid injection around sciatic nerves at the level of superior gemellus in treating our patient’s neuropathic pain.     

Elektrische Nervenstimulation bei peripheren Nervenblockaden

Background

The use of nerve stimulation is a common standard procedure for peripheral nerve blocks. However, ultrasound guidance is increasingly being used as an alternative. This study explored the relationship between needle positioning defined by ultrasound guidance and the electrical nerve stimulation before and after injection of 5% glucose solution (G5%).

Patients and methods

After obtaining permission from the ethics committee, 60 patients were enrolled in the study and the results from 51 patients could be analyzed. For sonographically defined correct needle placement the lowest electrical threshold of the elicited motor responses before and after injection of 1 ml G5% was determined.

Results

In 76% of cases nerve structures could be visualized with high quality and 90% of the blocks were successful. Only 29% of patients with a successful block showed a motor response with a stimulation current ≤0.5 mA. There was a relationship only between the quality of the visualization and the success of the blockade. Addition of G5% did not result in significant changes in stimulation thresholds.

Conclusion

With the protocol used the success of a blockade depends only on the quality of visualization. With correct ultrasound-guided needle tip positioning the electrical information seems to be skewed and doubtful.     

Peripheral neuropathy caused by joint-related cysts: a review of 17 cases

Background

Clinical compression neuropathy caused by para-articular cysts is rare. Only recently, the unifying articular theory was proposed to clarify its true etiologic nature. The authors attribute 17 cases to this theory in order to illustrate the shift in the diagnostic and treatment protocol, and the possible impact on patient outcome.

Methods

Eight intraneural and nine extraneural cysts were included. The proposed diagnostic protocol includes electromyography and ultrasound, followed by magnetic resonance imaging to characterize the cyst. The proposed treatment protocol consists of (1) ligation of the pedicle connecting the cyst with the afflicted joint, (2) decompression of the nerve and, when needed and (3) disarticulation of the superior tibiofibular joint (in case of peroneal nerve involvement).

Results

Outcome was good to excellent in all patients, with recovery of sensory and motor function. Cyst recurrence was observed in three intraneural cases (18?%). Analysis of our own diagnostic protocol showed that atypical compression neuropathies should follow a strict diagnostic protocol to exclude missing the presence of a cyst. Ultrasound needs to play a crucial role, with MRI for cyst characterization and pedicle identification.

Conclusions

Retrospective proof in favor of the articular theory was found in all cases. An explanation for the cyst recurrences was formed based on the articular theory. In addition, a diagnostic and therapeutic protocol is proposed for all atypical peripheral compression neuropathies with the ultimate goal to achieve optimal patient outcome.