[To determine the value of iMAX, a new electrodiagnostic method, and its application in the evaluation of peripheral motor nerve excitability].

Objective: To test the new method of iMAX (the minimum stimulus current that elicits the maximum compound muscle action potential amplitude) electrodiagnosis, verify the feasibility of this method in evaluating the excitability of peripheral motor axons, and preliminarily explore the clinical application value. Methods: This study was a cross-sectional study. A total of 50 healthy subjects were recruited from the outpatient department of Peking University Third Hospital from June 2022 to March 2023, including 25 males and 25 females, aged 25-68 (48±8) years. Eleven patients with Charcot-Marie-Pain-1A (CMT1A), 7 males and 4 females, aged 19-55 (41±13) years and 21 patients with diabetic peripheral neuropathy (DPN), 10 males and 11 females, aged 28-79 (53±16) years were enrolled in this study. iMAX of bilateral median nerves, ulnar nerves and peroneal nerves were detected in all patients. Repeatable motor responses with minimum motor threshold and amplitude of at least 0.1 mV and the minimum stimulus current intensity, at which the maximum compound muscle action potential amplitude is elicited, were measured respectively [1 mA increment is called (iUP) and, 0.1 mA adjustment is called (iMAX)].Comparison of the parameters: the parameters of threshold, iUP and iMAX were compared among different age groups, genders and sides, body mass index(BMI) values and detection time , as well as between CMT1A patients, DPN patients and healthy subjects. Results: In healthy subjects, the threshold, iUP value and iMAX value were (1.8±0.7) mA, (4.4±1.2) mA, and (4.2±1.3) mA respectively; ulnar nerve (3.1±1.6) mA, (6.8±3.2) mA, (6.4±3.2) mA; peroneal nerve (3.7±2.0) mA, (7.8±2.8) mA, (7.4±2.9) mA. There were statistically significant differences in threshold, iUP value and iMAX value among different age groups (all P<0.001).With the increase of age, there was a trend of increasing threshold, iUP, and iMAX values in different nerves, and the differences are statistically significant (all P<0.001). There were no significant differences in gender, side and detection time threshold, iUP value and iMAX value (all P>0.05). The parameters of healthy subjects with high BMI value were higher than those of healthy subjects with low BMI value(all P<0.05). Compared with the healthy subjects, the parameters of 11 CMT1A patients were significantly increased (all P<0.05), and the parameters of 21 DPN patients were slightly increased (P<0.05). Conclusion: The new iMAX method reflects the excitability of motor axons and early axonal dysfunction, which is an important supplement to the traditional nerve conduction, and can be used to monitor motor axon excitability disorders.

Ulnar neuropathy.

Ulnar neuropathy at the elbow is the second most common compressive neuropathy. Less common, although similarly disabling, are ulnar neuropathies above the elbow, at the forearm, and the wrist, which can present with different combinations of intrinsic hand muscle weakness and sensory loss. Electrodiagnostic studies are moderately sensitive in diagnosing ulnar neuropathy, although their ability to localize the site of nerve injury is often limited. Nerve imaging with ultrasound can provide greater localization of ulnar injury and identification of specific anatomical pathology causing nerve entrapment. Specifically, imaging can now reliably distinguish ulnar nerve entrapment under the humero-ulnar arcade (cubital tunnel) from nerve injury at the retro-epicondylar groove. Both these pathologies have historically been diagnosed as either "ulnar neuropathy at the elbow," which is non-specific, or "cubital tunnel syndrome," which is often erroneous. Natural history studies are few and limited, although many cases of mild-moderate ulnar neuropathy at the elbow appear to remit spontaneously. Conservative management, perineural steroid injections, and surgical release have all been studied in treating ulnar neuropathy at the elbow. Despite this, questions remain about the most appropriate management for many patients, which is reflected in the absence of management guidelines.

Serial repetitive nerve stimulation studies in organophosphorus poisoning indicate two distinct pathophysiological processes occur at the neuromuscular junction in the intermediate syndrome.

INTRODUCTION: Intermediate syndrome is an important cause of respiratory failure following acute organophosphorus pesticide poisoning. The objective of this study was to examine the pathophysiology of this syndrome by analysis of sequential repetitive nerve stimulation studies in patients with acute organophosphorus pesticide poisoning. METHODS: Thirty-four consenting symptomatic patients with acute organophosphorus pesticide poisoning with intermediate syndrome (n = 10) or a milder forme fruste intermediate syndrome (n = 24) were assessed prospectively with daily physical examination and repetitive nerve stimulation done on the right and left median and ulnar nerves. The compound muscle action potential at 1, 3, 10, 15, 20 and 30 Hertz was measured with a train of ten stimuli. The amplitudes of the resulting stimuli were normalized to the first stimulus (100 per cent) and plotted against time. The decrease in the area under the curve of all the second stimulus compound muscle action potentials in the first 0.3 seconds was measured as a means of quantifying the refractory block. The decrease in the area under the curve under the 10, 15, 20 and 30 Hertz compound muscle action potentials relative to this pooled second stimulus compound muscle action potentials-area under the curve indicated the extent of additional rate-dependent block (decreasing compound muscle action potential-area under the curve over the first 0.3 seconds after the first stimulus with increasing Hertz). RESULTS: These new measurements strongly correlated with the severity of weakness. Refractory block was seen in most patients but was more severe in those with intermediate syndrome than those with forme fruste (partial) intermediate syndrome (median 55 per cent versus 16 per cent, P = 0.0001). Similar large differences were found for rate-dependent block (30 per cent versus 7 per cent, P = 0.001), which was uncommon in forme fruste intermediate syndrome but found in nine out of 10 patients with intermediate syndrome. Rate dependent block was generally only observed after 24 hours. The simplest strong predictor was total block at 30 Hertz repetitive nerve stimulation (89 per cent [interquartile range 73 to 94 per cent] versus 21 per cent [4 to 55 per cent]; P < 0.0001), which was very similar to total block calculated by summing other calculations. DISCUSSION: These findings likely represent depolarization and desensitization block from prolonged excessive cholinergic stimulation but it is not clear if these are from pre- or post-synaptic pathology. An animal model of intermediate syndrome with repetitive nerve stimulation studies might enable a better pathophysiological understanding of the two types of block. LIMITATIONS: The limited number of repetitive nerve stimulation studies performed were sufficient to demonstrate proof-of-concept, but further studies with more patients are needed to better define the correlates, clinical relevance and possible diagnostic/prognostic roles for the use of this technique. CONCLUSION: There are two easily distinguishable pathophysiological abnormalities in the neuromuscular block in intermediate syndrome. While they often coincide, both may be observed in isolation. The total and rate-dependent block at 30 Hertz are strongly associated with more severe weakness.

Safe zones in dorsal portals for wrist arthroscopy: a cadaveric study.

The standard dorsal portals are the most commonly used in wrist arthroscopy. This cadaveric study aims to determine safe zones, by quantitatively describing the neurovascular relationships of the dorsal wrist arthroscopy portals: 1-2, 3-4, midcarpal radial, midcarpal ulnar, 4-5, 6-radial and 6-ulnar. The neurovascular structures of twenty-one fresh frozen human cadaveric upper limbs were exposed, while the aforementioned portals were established with needles through portal sites. The minimum distance between portals and: dorsal carpal branch of radial artery, superficial branch of radial nerve, posterior interosseous nerve and dorsal branch of ulnar nerve, were measured accordingly with a digital caliper, followed by statistical analysis of the data. The median and interquartile range for each portal to structures at risk were determined and a safe zone around each portal was established. Free of any neurovascular structure safe zones surrounding 1-2, 3-4, midcarpal radial, midcarpal ulnar, 4-5, 6-radial and 6-ulnar portals were found at 0.46mm, 2.33mm, 10.73mm, 11.01mm, 10.38mm, 5.95mm and 0.64mm respectively. Results of statistical analysis from comparisons between 1-2, 3-4 and midcarpal radial portals, indicated that 1-2 was the least safe. The same analysis among 3-4, midcarpal radial, midcarpal ulnar and 4-5 portals indicated that midcarpal portals were safer, while 3-4 was the least safe. Results among midcarpal ulnar, 4-5, 6-radial and 6-ulnar portals indicated that 6-radial and specifically 6-ulnar were the least safe. This study provides a safe approach to the dorsal aspect of the wrist, enhancing established measurements and further examining safety of the posterior interosseous nerve.

Cubital tunnel release with Wide Awake Local Anaesthesia No Tourniquet (WALANT) technique in an outpatient setting is safe and effective.

Ulnar nerve release is often performed under general anaesthesia. Wide Awake Local Anaesthesia No Tourniquet (WALANT) is a new anaesthetic method increasingly used by hand surgeons in an outpatient setting. It has advantages such as the possibility to shift surgical interventions out of the regular surgical theatre settings into an outpatient clinical setting, no risk of complications or side effects resulting from regional and general anesthesia and decreased costs. The use of WALANT has not been investigated extensively in elbow surgery. This study aims to evaluate clinical outcomes after ulnar nerve release under WALANT 27 patients with ulnar nerve release for cubital tunnel syndrome were included. The primary outcome was the presence of (remaining) symptoms after ulnar nerve release. Data was extracted from medical records. 13 out of 27 patients had (mild) remaining symptoms after ulnar nerve release, and 1 complication (superficial wound infection) was seen. Ulnar nerve release under WALANT is safe and effective in patients with primary ulnar nerve entrapment that have failed conservative therapy.

Optimizing donor fascicle selection in Oberlin's procedure: A retrospective review of anatomical variability using intraoperative neuromonitoring.

BACKGROUND: Transfer of the fascicle carrying the flexor carpi ulnaris (FCU) branch of the ulnar nerve (UN) to the biceps/brachialis muscle branch of the musculocutaneous nerve (Oberlin's procedure), is a mainstay technique for elbow flexion restoration in patients with upper brachial plexus injury. Despite its widespread use, there are few studies regarding the anatomic location of the donor fascicle for Oberlin's procedure. Our report aims to analyze the anatomical variability of this fascicle within the UN, while obtaining quantifiable, objective data with intraoperative neuromonitoring (IONM) for donor fascicle selection. METHODS: We performed a retrospective review of patients at our institution who underwent an Oberlin's procedure from September 2019 to July 2023. We used IONM for donor fascicle selection (greatest FCU muscle and least intrinsic hand muscle activation). We prospectively obtained demographic and electrophysiological data, as well as anatomical location of donor fascicles and post-surgical morbidities. Surgeon's perception of FCU/intrinsic muscle contraction was compared to objective muscle amplitude during IONM. RESULTS: Eight patients were included, with a mean age of 30.5 years and an injury-to-surgery interval of 4 months. Donor fascicle was located anterior in two cases, posterior in two, radial in two and ulnar in two patients. Correlation between surgeon's perception and IONM findings were consistent in six (75%) cases. No long term motor or sensory deficits were registered. CONCLUSIONS: Fascicle anatomy within the UN at the proximal arm is highly variable. The use of IONM can aid in optimizing donor fascicle selection for Oberlin's procedure.

Timing of surgery in peripheral nerve injury of the upper extremity.

Peripheral nerve injuries present a complex clinical challenge, requiring a nuanced approach in surgical management. The consequences of injury vary, with sometimes severe disability, and a risk of lifelong pain for the individual. For late management, the choice of surgical techniques available range from neurolysis and nerve grafting to tendon and nerve transfers. The choice of technique utilized demands an in-depth understanding of the anatomy, patient demographics and the time elapsed since injury for optimized outcomes. This paper focuses on injuries to the radial, median and ulnar nerves, outlining the authors' approach to these injuries.Level of evidence: IV.

Volumetric assessment of ulnar nerves in cubital tunnel syndrome with 3D modeling of the MRI and its relationship with electrodiagnostic findings.

BACKGROUND: Thickened nerve cross-sectional areas (CSA) have been investigated in compressive neuropathy, but the longitudinal extent of nerve swelling has yet to be evaluated. We did a volumetric assessment of the ulnar nerve in cubital tunnel syndrome (CuTS) with three-dimensional (3D) magnetic resonance imaging (MRI) modeling and investigated this relationship with clinical and electrodiagnostic parameters. METHODS: We compared 40 CuTS patient elbow MRIs to 46 patient elbow MRIs with lateral elbow epicondylitis as controls. The ulnar nerve was modeled with Mimics software and was assessed qualitatively and quantitatively. The CSA and ulnar nerve volumes were recorded, and the area under the receiver operating characteristic (ROC) curve was calculated for diagnostic performance. We analyzed clinical and electrodiagnostic parameters to investigate their relationship with the 3D ulnar nerve parameters. RESULTS: For the diagnosis of CuTS, the area under the curve value was 0.915 for the largest CSA and 0.910 for the volume in the ROC curve. The optimal cut-off was 14.53 mm2 and 529 mm3 respectively. When electrodiagnostic parameters were investigated, the 3D ulnar nerve volume was significantly inversely associated with motor conduction velocity, although there was no association between the largest CSA and any of the electrodiagnostic parameters. CONCLUSIONS: The 3D ulnar nerve volume, which is an integration or multilevel measurement of CSAs, showed diagnostic usefulness similar to CSA, but it correlated better with conduction velocity, indicating demyelination or early-to-moderate nerve damage in CuTS.

A compressomyograph train of four monitoring device.

The monitoring of the neuromuscular blockade is critical for patient's safety during and after surgery. The monitoring of neuromuscular blockade often requires the use of Train of Four (TOF) technique. During a TOF test two electrodes are attached to the ulnar nerve, and a series of four electric pulses are applied. The electrical stimulation causes the thumb to twitch, and the amount of twitch varies depending on the amount of neuromuscular blockade in patient's system. Current medical devices used to assist anesthesiologists to perform TOF monitoring often require free hand movement and do not provide accurate or reliable results. The goal of this work is to design, prototype and test a new medical device that provides reliable TOF results when thumb movement is restricted. A medical device that uses a pressurized catheter balloon to detect the response thumb twitch of the TOF test is created. An analytical model, numerical study, and mechanical finger testing were employed to create an optimum design. The design is tested through a pilot human subjects study. No significant correlation is reported with subjects' properties, including hand size.

Long-standing Nonunited Fracture Lateral Humeral Condyle in Children. Evaluating a Two-stage Surgical Treatment Strategy With Critical Review.

OBJECTIVE: This work aimed to evaluate the results of using a 2-stage surgical treatment strategy without doing anterior transposition of the ulnar nerve (ATUN) for cases with long-standing nonunited fracture lateral humeral condyle (LHC) in children, accompanied by a critical review. METHODS: A consecutive 12 children with a long-standing ">2 years" nonunited LHC with evident radiologic gross anatomic distortion of the elbow were included in this study. A 2-stage surgical treatment strategy was applied, wherein the first stage, open functional reduction, osteosynthesis, and iliac bone graft were done. Then after 6 months, the second stage surgery was carried out in the form of supracondylar humeral corrective osteotomy if the cubitus valgus angle was ≥20 degrees. ATUN was not done for any of the cases even with those having ulnar nerve dysfunction. RESULTS: Union took place in 11 out of the 12 cases after a mean follow-up period of 11 weeks (range: 8 to 14 wk; SD: 1.6). All the 7 cases showed preoperative ulnar nerve dysfunction and reported clinical recovery at the end of their follow-up. CONCLUSIONS: Two-stage surgical treatment strategy without ATUN is a convenient, reproducible, and successful line of treatment for children presented with longstanding nonunited LHC with anatomically distorted elbow. LEVEL OF EVIDENCE: Level IV-case series.

Assessing ulnar neuropathy at the elbow using magnetoneurography.

OBJECTIVE: To measure neuromagnetic fields of ulnar neuropathy patients at the elbow after electrical stimulation and evaluate ulnar nerve function at the elbow with high spatial resolution. METHODS: A superconducting quantum interference device magnetometer system recorded neuromagnetic fields of the ulnar nerve at the elbow after electrical stimulation at the wrist in 16 limbs of 16 healthy volunteers and 21 limbs of 20 patients with ulnar neuropathy at the elbow. After artifact removal, neuromagnetic field signals were processed into current distributions, which were superimposed onto X-ray images for visualization. RESULTS: Based on the results in healthy volunteers, conduction velocity of 30 m/s or 50% attenuation in current amplitude was set as the reference value for conduction disturbance. Of the 21 patient limbs, 15 were measurable and lesion sites were detected, whereas 6 limbs were unmeasurable due to weak neuromagnetic field signals. Seven limbs were deemed normal by nerve conduction study, but 5 showed conduction disturbances on magnetoneurography. CONCLUSIONS: Measuring the magnetic field after nerve stimulation enabled visualization of neurophysiological activity in patients with ulnar neuropathy at the elbow and evaluation of conduction disturbances. SIGNIFICANCE: Magnetoneurography may be useful for assessing lesion sites in patients with ulnar neuropathy at the elbow.

Ex-vivo systems for neuromodulation: A comparison of ex-vivo and in-vivo large animal nerve electrophysiology.

BACKGROUND: Little research exists on extending ex-vivo systems to large animal nerves, and to the best of our knowledge, there has yet to be a study comparing these against in-vivo data. This paper details the first ex-vivo system for large animal peripheral nerves to be compared with in-vivo results. NEW METHOD: Detailed ex-vivo and in-vivo closed-loop neuromodulation experiments were conducted on pig ulnar nerves. Temperatures from 20 °C to 37 °C were evaluated for the ex-vivo system. The data were analysed in the time and velocity domains, and a regression analysis established how evoked compound action potential amplitude and modal conduction velocity (CV) varied with temperature and time after explantation. MAIN RESULTS: Pig ulnar nerves were sustained ex-vivo up to 5 h post-explantation. CV distributions of ex-vivo and in-vivo data were compared, showing closer correspondence at 37 °C. Regression analysis results also demonstrated that modal CV and time since explantation were negatively correlated, whereas modal CV and temperature were positively correlated. COMPARISON WITH EXISTING METHODS: Previous ex-vivo systems were primarily aimed at small animal nerves, and we are not aware of an ex-vivo system to be directly compared with in-vivo data. This new approach provides a route to understand how ex-vivo systems for large animal nerves can be developed and compared with in-vivo data. CONCLUSION: The proposed ex-vivo system results were compared with those seen in-vivo, providing new insights into large animal nerve activity post-explantation. Such a system is crucial for complementing in-vivo experiments, maximising collected experimental data, and accelerating neural interface development.

The 2-by-2 Inch "Key Window" in the Upper Extremity: An Anatomical Appraisal of the Accessibility and Proximity of the Major Nerves and Vessels.

BACKGROUND: The brachial plexus is a network of nerves located between the neck and axilla, which receives input from C5-T1. Distally, the nerves and blood vessels that supply the arm and forearm form a medial neurovascular bundle. The purpose of this study was to illustrate that a peripheral nerve dissection via a 2 × 2 inch window would allow for identification and isolation of the major nerves and blood vessels that supply the arm and forearm. METHODS: A right side formalin-fixed latex-injected cadaveric arm was transected at the proximal part of the axillary fold and included the scapular attachments. Step-by-step anatomical dissection was carried out and documented with three-dimensional digital imaging. RESULTS: A 2 × 2 inch window centered 2 inches distal to the axillary fold on the medial surface of the arm enabled access to the major neurovascular structures of the arm and forearm: the median nerve, ulnar nerve, medial antebrachial cutaneous nerve, radial nerve and triceps motor branches, musculocutaneous nerve and its biceps and brachialis branches and lateral antebrachial cutaneous nerve, basilic vein and brachial artery and vein, and profunda brachii artery. CONCLUSIONS: Our study demonstrates that the majority of the neurovascular supply in the arm and forearm can be accessed through a 2 × 2 inch area in the medial arm. Although this "key window" may not be entirely utilized in the operative setting, our comprehensive didactic description of peripheral nerve dissection in the cadaver laboratory can help in safer identification of complex anatomy encountered during surgical procedures.

Ultrasound of the Ulnar Nerve: A Pictorial Review: Part 2: Pathological Ultrasound Findings.

This is the second part of a two-part article in which we focus on the ultrasound (US) appearance of the pathological ulnar nerve (UN) and its main branches. Findings in a wide range of our pathological cases are presented with high-resolution US images obtained with the latest-generation US machines and transducers.

Comprehensive analysis and classification of retrocondylar ulnar groove morphology using CT imaging in an average population of adults.

PURPOSE: Anatomical variations of the concave shaped retrocondylar ulnar groove (RUG) can contribute to ulnar nerve instability. However, there are currently limited available standardized data describing the anatomy of the RUG based on radiologic imaging, such as computed tomography (CT). This study aims to provide a comprehensive description and classification of RUG anatomy based on RUG angle measurements. METHODS: 400 CT scans of the elbows of adults showing no signs of osseous damage were evaluated. RUG angles were measured in four anatomically defined axial planes that spanned from the proximal to the distal end of the RUG. Furthermore, distance measurements at the medial epicondyle were conducted. A classification system for the RUG is proposed based on the acquired RUG angles, aiming to categorize the individual angles according to the 25th and 75th percentiles. RESULTS: RUG angles were significantly larger in males compared to females (p < 0.001) accompanied by larger distances including the off-set and height of the medial epicondyle (p < 0.001). RUG angles decreased from proximal to distal locations (p < 0.05). CONCLUSION: This study revealed that men exhibited larger RUG angles compared to women, indicating a less-concave shape of the RUG in men. Introducing an objective RUG classification system can improve our understanding of anatomical variations and potentially find application in diagnostics and preoperative planning.

Usability of Nerve Tape: A Novel Sutureless Nerve Coaptation Device.

PURPOSE: Microsuture neurorrhaphy is technically challenging and has inherent drawbacks. This study evaluated the potential of a novel, sutureless nerve coaptation device to improve efficiency and precision. METHODS: Twelve surgeons participated in this study-six attending hand/microsurgeons and six trainees (orthopedic and plastic surgery residents or hand surgery fellows). Twenty-four cadaver arm specimens were used, and nerve repairs were performed at six sites in each specimen-the median and ulnar nerves in the proximal forearm, the median and ulnar nerves in the distal forearm, and the common digital nerves to the second and third web spaces. Each study participant performed nerve repairs at all six injury locations in two different cadaver arms (n = 12 total repairs for each participating surgeon). The nerve repairs were timed, tested for tensile strength, and graded for alignment and technical repair quality. RESULTS: A substantial reduction in time was required to perform repairs with the novel coaptation device (1.6 ± 0.8 minutes) compared with microsuture (7.2 ± 3.6 minutes). Device repairs were judged clinically acceptable (scoring "Excellent" or "Good" by most of the expert panel) in 97% of the repairs; the percentage of suture repairs receiving Excellent/Good scores by most of the expert panel was 69.4% for attending surgeons and 36.1% for trainees. The device repairs exhibited a higher average peak tensile force (7.0 ± 3.6 N) compared with suture repairs (2.6 ± 1.6 N). CONCLUSIONS: Nerve repairs performed with a novel repair device were performed faster and with higher technical precision than those performed using microsutures. Device repairs had substantially greater tensile strength than microsuture repairs. CLINICAL RELEVANCE: The evaluated novel nerve repair device may improve surgical efficiency and nerve repair quality.

Ultrasonographic evaluation of ulnar nerve morphology in patients with ulnar nerve instability.

INTRODUCTION/AIMS: Ulnar nerve instability (UNI) in the retroepicondylar groove is described as nerve subluxation or dislocation. In this study, considering that instability may cause chronic ulnar nerve damage by increasing the friction risk, we aimed to examine the effects of UNI on nerve morphology ultrasonographically. METHODS: Asymptomatic patients with clinical suspicion of UNI were referred for further clinical and ultrasonographic examination. Based on ulnar nerve mobility on ultrasound, the patients were first divided into two groups: stable and unstable. The unstable group was further divided into two subgroups: subluxation and dislocation. The cross-sectional area (CSA) of the nerve was measured in three regions relative to the medial epicondyle (ME). RESULTS: In the ultrasonographic evaluation, UNI was identified in 59.1% (52) of the 88 elbows. UNI was bilateral in 50% (22) of the 44 patients. Mean CSA was not significantly different between groups. A statistically significant difference in ulnar nerve mobility was found between the group with CSA of <10 versus ≥10 mm2 (p = .027). Nerve instability was found in 85.7% of elbows with an ulnar nerve CSA value of ≥10 mm2 at the ME level. DISCUSSION: The probability of developing neuropathy in patients with UNI may be higher than in those with normal nerve mobility. Further prospective studies are required to elucidate whether asymptomatic individuals with UNI and increased CSA may be at risk for developing symptomatic ulnar neuropathy at the elbow.

[Rare Compression Syndrome of the Median Nerve due to a Supracondylar Humeral Process and a Ligament of Struthers]. / Seltenes Kompressionssyndrom des N. medianus durch den Processus supracondylaris und das Struthers-Ligament.

INTRODUCTION: A supracondylar process is a bony spur on the distal anteromedial surface of the humerus, and it is considered an anatomical variant with a prevalence of 0.4-2.7% according to anatomical studies. In almost all cases, it is associated with a fibrous, sometimes ossified ligament, which extends from the supracondylar process to the medial epicondyle. This ligament is known in the literature as the ligament of Struthers, named after the Scottish anatomist who first described it in detail in 1854. In rare cases, the supracondylar process can be a clinically relevant finding as a cause of nerve compression syndrome. The median and ulnar nerve can be trapped by the ring-shaped structure formed by the ligament of Struthers and the supracondylar process. CASE REPORT: A 59-year-old patient with symptoms of a cubital tunnel syndrome and additional ipsilateral sensory deficits in his thumb was referred to our clinic. Electroneurography showed no signs of an additional carpal tunnel syndrome. Preoperative x-ray and CT scans of the upper arm revealed a supracondylar process, which led us to suspect an associated entrapment of the median nerve. An MRI scan of the upper arm showed a ligament of Struthers and signs of a related median nerve compression as we initially assumed. We performed a surgical decompression of the median nerve in the distal upper arm and of the ulnar nerve in the cubital tunnel. Intraoperatively, there was evidence of compression of the median nerve due to the supracondylar process and the ligament of Struthers. The latter was cleaved and then resected along with the supracondylar process. Three months after surgery, the patient had no motor or sensory deficits. SUMMARY: The ring-shaped structure formed by the supracondylar process and ligament of Struthers represents a rare cause of compression syndrome of the median and ulnar nerve. Its incidence remains unknown so far. This anatomical variant should be considered a differential diagnosis in case of possibly related nerve entrapment symptoms after ruling out other, more frequent nerve compression causes. Moreover, the supracondylar process should be completely resected including the periosteum during surgery to minimise the risk of recurrence.

Typical CIDP, distal variant CIDP, and anti-MAG antibody neuropathy: An ultra-high frequency ultrasound comparison of nerve structure.

To date, little is known about the usefulness of ultra-high frequency ultrasound (UHF-US, 50-70 MHz) in clinical practice for the diagnosis of dysimmune neuropathies. We present a prospective study aimed at comparing UHF-US alterations of nerves and fascicles in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), distal CIDP (d-CIDP) and anti-MAG neuropathy and their relationships with clinical and electrodiagnostic (EDX) features. 28 patients were included (twelve CIDP, 6 d-CIDP and 10 anti-MAG) and ten healthy controls. Each patient underwent neurological examination, EDX and UHF-US study of median and ulnar nerves bilaterally. UHF-US was reliable in differentiating immune neuropathies from controls when using mean and/or segmental nerve and/or fascicle cross-sectional area (CSA); furthermore, fascicle ratio (fascicle/nerve CSA) was a reliable factor for differentiating d-CIDP from other types of polyneuropathies. The fascicle CSA appears to be more increased in CIDP and its variant than in anti-MAG neuropathy. UHF-US offers information beyond simple nerve CSA and allows for a better characterization of the different forms of dysimmune neuropathies.

Bony encasement of the ulnar nerve secondary to heterotopic ossification of the elbow: an evaluation of long-term outcomes.

BACKGROUND: Ulnar neuropathy at the elbow caused by heterotopic ossification (HO) is a rare condition. This retrospective study aims to report on 32 consecutive cases of ulnar nerve encasement caused by elbow HO and evaluate long-term outcomes of operative management and a standardized postoperative rehabilitation regimen. METHODS: A retrospective case series was conducted on 32 elbows (27 patients) that underwent operative management of bony ulnar nerve encasement. All procedures were performed in the inpatient setting at an Academic Level 1 Trauma Center from September 1999 to July 2021 by one of 3 fellowship-trained shoulder and elbow. Postoperatively, all patients received formal physical therapy, HO prophylaxis (30 received indomethacin, 2 received radiation), and a structured continuous passive motion machine regimen. Patient demographics, age, gender, type of injury, history of tobacco use, and medical comorbidities were obtained to include in the analysis. Long-term follow-up examinations were performed to evaluate elbow flexion-extension arc of motion, Mayo Elbow Performance Score, and visual analog scale pain scores. RESULTS: Thirty-two elbows with complete bony ulnar nerve encasement secondary to HO were identified (14 from burns, 15 from trauma, 3 closed head injuries). Following surgery, the mean flexion-extension arc of motion improved significantly, increasing from 21° to 100° at long-term follow-up (average 8.7 years, range 2-17 years), with statistically significant improvements in preoperative vs. long-term postoperative elbow extension (P < .001), flexion (P < .001), and total arc of motion (P < .001). There was a statistically significant improvement in pre- vs. postprocedure ulnar nerve function, as demonstrated by a decrease in average McGowan grade (1.2-0.7; P = .002). Additionally, 63% of patients with preoperative ulnar neuropathy symptoms (20/32) had either complete resolution or subjective improvement after surgery. The mean time from injury to surgery was 518 days (range 65-943 days). Age, gender, time to surgery, and medical comorbidities were not associated with outcomes. The complication rate was 9% (3/32). Patients had an average flexion-extension arc of motion of 97° and average Mayo Elbow Performance Score of 80 ("good") at long-term follow-up. CONCLUSIONS: The combination of operative management, postoperative HO prophylaxis, and a regimented rehabilitation program has proven to be a durable solution for treating and ensuring good long-term functional outcomes for patients with elbow HO and bony ulnar nerve encasement. This treatment approach leads to superior range of motion, improved or resolved ulnar neuropathy, and good to excellent long-term functional outcomes.