Prevalence of bifid median nerves and persistent median arteries and their association with carpal tunnel syndrome in a sample of Latino poultry processors and other manual workers

Automated segmentation of the median nerve in patients with carpal tunnel syndrome

Machine learning and deep learning are novel methods which are revolutionizing medical imaging. In our study we trained an algorithm with a U-Net shaped network to recognize ultrasound images of the median nerve in the complete distal half of the forearm and to measure the cross-sectional area at the inlet of the carpal tunnel. Images of 25 patient hands with carpal tunnel syndrome (CTS) and 26 healthy controls were recorded on a video loop covering 15 cm of the distal forearm and 2355 images were manually segmented. We found an average Dice score of 0.76 between manual and automated segmentation of the median nerve in its complete course, while the measurement of the cross-sectional area at the carpal tunnel inlet resulted in a 10.9% difference between manually and automated measurements. We regard this technology as a suitable device for verifying the diagnosis of CTS.

Thrombosed Persistent Median Artery with Coexisting Bifid Median Nerve in a Robotic Arthroplasty Surgeon: A Case Report

CASE

A 47-year-old orthopaedic surgeon presented with acute volar left wrist pain. He performed over 250 robot-assisted knee arthroplasties each year. Color Doppler evaluation revealed bilateral persistent median arteries and bifid median nerves, with focal occlusive thrombosis of the left median artery. He was advised rest and oral aspirin. He could return to his professional activities after 1 month. He had no recurrence of symptoms at 1 year of follow-up.

CONCLUSION

Orthopaedic surgeons use vibrating hand tools on a daily basis. The possibility of hand-arm vibration syndrome must be considered in the differential diagnosis of wrist pain among orthopaedic surgeons.

Carpal Tunnel Syndrome Resulting From Persistent Median Artery and Bifid Median Nerve: The Critical Role of Ultrasonography

Here, we present a 37-year-old right-handed female patient who presented with increasing paresthesia, tingling, and numbness in the radial palm and lateral three fingers of her right hand for six months. Because of the intense wrist discomfort and unilateral involvement, ultrasonography was used to evaluate the patient in addition to a nerve conduction study to exclude secondary causes of carpal tunnel syndrome.

Application of deep learning algorithms in automatic sonographic localization and segmentation of the median nerve: A systematic review and meta-analysis

OBJECTIVE

High-resolution ultrasound is an emerging tool for diagnosing carpal tunnel syndrome caused by the compression of the median nerve at the wrist. This systematic review and meta-analysis aimed to explore and summarize the performance of deep learning algorithms in the automatic sonographic assessment of the median nerve at the carpal tunnel level.

METHODS

PubMed, Medline, Embase, and Web of Science were searched from the earliest records to May 2022 for studies investigating the utility of deep neural networks in the evaluation of the median nerve in carpal tunnel syndrome. The quality of the included studies was evaluated using the Quality Assessment Tool for Diagnostic Accuracy Studies. The outcome variables included precision, recall, accuracy, F-score, and Dice coefficient.

RESULTS

In total, seven articles were included, comprising 373 participants. The deep learning and related algorithms comprised U-Net, phase-based probabilistic active contour, MaskTrack, ConvLSTM, DeepNerve, DeepSL, ResNet, Feature Pyramid Network, DeepLab, Mask R-CNN, region proposal network, and ROI Align. The pooled values of precision and recall were 0.917 (95 % confidence interval [CI], 0.873-0.961) and 0.940 (95 % CI, 0.892-0.988), respectively. The pooled accuracy and Dice coefficient were 0.924 (95 % CI, 0.840-1.008) and 0.898 (95 % CI, 0.872-0.923), respectively, whereas the summarized F-score was 0.904 (95 % CI, 0.871-0.937).

CONCLUSION

The deep learning algorithm enables automated localization and segmentation of the median nerve at the carpal tunnel level in ultrasound imaging with acceptable accuracy and precision. Future research is expected to validate the performance of deep learning algorithms in detecting and segmenting the median nerve along its entire length as well as across datasets obtained from various ultrasound manufacturers.

Accessory Hand Muscles Over the Transverse Carpal Ligament: An Obstacle in Carpal Tunnel Surgery

BACKGROUND

Carpal tunnel syndrome (CTS) is an entrapment neuropathy caused by compression of the median nerve throughout the carpal tunnel. It is the most common entrapment neuropathy, with an estimated prevalence of 4%-7%. Surgical management is more effective in moderate to severe and severe CTS. CTS recurs in approximately 20% of patients, and up to 12% of these patients require reoperation. Knowledge of normal anatomy and variations would improve the success rate of the index surgery. Atypical causes of CTS were reported, including ganglion cysts, synovial hypertrophy, lipomas, bone fracture, bone fragments, tumor of soft tissues or bones, neurofibromas, neuromas, vascular malformations, and accessory muscles. Accessory muscles are commonly detected in upper limbs. However, their concomitant presentation with CTS has rarely been reported. We aimed to present different accessory muscles diagnosed during CTS surgery through a systematic review of the literature with our exemplary case.

METHODS

A systematic review/meta-analysis was performed concomitant with a case presentation.

RESULTS

Accessory muscles associated with CTS were as follows: palmaris longus, 28.6%; lumbrical muscles, 19.3%; palmaris profundus, 17.8%; flexor digitorum superficialis, 16.1%; transverse carpal muscle, 5%; flexor digitorum indicis, 4.2%; flexor superficialis indicis, 4.2%; flexor sublimis, 0.8%; accessory superficialis longus, 0.8%; flexor pollicis longus, 0.8%; abductor digiti minimi, 0.8%; abductor digiti quinti, 0.8%; and flexor digitorum superficialis brevis, 0.8%. Accessory muscles were mostly noticed during CTS surgery (88.2%).

CONCLUSIONS

Knowledge of possible variations within the carpal tunnel would improve the surgeon's capability during CTS surgery.

[Trifid median nerve. A rare anatomical variant in sonographic evaluation of carpal tunnel]

The ultrasound study for the diagnosis of carpal tunnel syndrome can reveal different anatomical variants. A rare variant is the presence of a trifid median nerve. The visualization of this anatomical variant may be of importance in the surgical planning of carpal tunnel syndrome. Fifty-two-year-old male, with a clinic compatible with bilateral carpal tunnel syndrome. In the ultrasound examination, a bifid median nerve appears as a finding in the right wrist and a trifid median nerve in the left wrist as anatomical variants. It is important to distinguish a trifid median nerve from a persistent median artery at the level of the carpal tunnel, much more frequent than the first. For this, the ultrasound visualization of the study area using the Doppler function is essential.

Carpal tunnel syndrome in rheumatoid arthritis patients: the role of combined ultrasonographic and electrophysiological assessment

Background

Carpal tunnel syndrome (CTS) is known as one of the most common neurological extra-articular manifestations in rheumatoid arthritis (RA) patients. Studies on CTS in RA depend mostly on electrophysiological assessment. Few studies have used ultrasonography for evaluation of the local causes with much focus on wrist arthritis and tenosynovitis as the main cause of entrapment neuropathy of the median nerve in RA. The aim of our study is to assess the local causes of carpal tunnel syndrome in rheumatoid arthritis patients by ultrasonography and whether inflammatory or anomalous variations could affect decision-making and patient management.

Results

Carpal tunnel syndrome was diagnosed in 71 out of 74 examined RA wrists by nerve conduction studies (NCSs) and was categorized from minimal to severe according to Padua et al.’s (Ital J Neurol Sci 18:145–50, 1997) grading criteria. Median nerve CSA at the level of the carpal tunnel inlet and flattening ratio showed statistically significant relation with CTS severity. Bifid MN was found in 20 wrists (10 mild CTS wrists and 10 moderate CTS wrists), a persistent median artery was found in 4 wrists with moderate CTS, and an accessory muscle bundle was present in 3 wrists (2 mild CTS and 1 moderate CTS). The majority of the examined hands (85.1%) showed flexor tendon tenosynovitis at the wrist level and radio-carpal joint synovitis. The US7-joint score using GSUS7 & PDUS7 for synovitis, tenosynovitis and erosions showed significant relation with patients’ disease activity by DAS28 score. Significant relations between CTS severity and the following nerve conduction studies’ parameters, median nerve distal motor latency (DML), motor/sensory NCV, peak sensory latency, amplitude of SNAP, and median-radial latency difference test, were observed.

Conclusion

Synovial inflammation and local causes of median nerve compression such as bifid median nerve, persistent median artery, and accessory muscle bundle are collectively contributing factors in the etiology of carpal tunnel syndrome in rheumatoid arthritis patients. Ultrasonographic visualization of these inflammatory and anomalous variations enables early detection of CTS and highlights the possibility of non-arthritic-related causes. Using the 7-joint ultrasound (US7) score for assessment of synovitis, tenosynovitis, and erosions in rheumatoid arthritis patients is of valuable role in reflecting inflammation and its relation to the development of CTS in RA patients.

Persistent Median Artery Thrombosis Causing a Bifid Median Nerve and Carpal Tunnel Syndrome: A Case Report

CASE

In this report, we describe a 41-year-old woman with symptoms concerning for acute carpal tunnel syndrome. Operative exploration resulted in resection of an aneurysmal, thrombosed, persistent median artery seen on preoperative imaging and full recovery by the patient.

CONCLUSION

A persistent median artery is an uncommon congenital hand condition resulting from the failure of the median artery to regress, which can then travel through the carpal tunnel and be associated with a bifid median nerve, irritation of the nerve, and need for surgical exploration if it thromboses, which is rare. This should be considered in patients with acute median nerve compression, without other etiologies.

Bifid median nerve as an anatomical risk factor for carpal tunnel syndrome: A meta-analysis

As the median nerve enters the carpal tunnel, it is a single nerve that soon bifurcates into lateral and medial branches into the hand. If the bifurcation is proximal to the carpel tunnel, a bifid median nerve results. Carpal tunnel syndrome is often associated with a bifid median nerve with or without a persistent median artery. Individual keywords and MeSH phrases were searched in the Google Scholar, SCOPUS, and PubMed databases. Full texts were then collected and assessed for suitability. The prevalence of bifid median nerve at the wrist joint in normal and carpal tunnel syndrome wrists (pre-canal part) and the mean difference between groups were recorded. Only human data were used to test the findings. The pooled odds ratio (with minimal heterogeneity) was 1.50 [1.17-1.93, 95% CI]. The bifid median nerve cross-sectional area (CSA) was significantly greater than that of a solitary median nerve in normal wrists. The mean difference in CSA between the two was 1.50 mm² [0.56-2.45 mm² , 95% CI] without heterogeneity (i²  = 0). Sex and laterality distributions scarcely differed between the two types of wrists. Owing to the insufficiency of data, the relationships with mean height and weight were not examined. There was a 50% greater incidence of bifid median nerves in carpal tunnel syndrome patients than in normal subjects. A bifid median nerve increases the mean CSA at the wrist joint by 1.5 mm² . These findings indicate that the bifid median nerve is an anatomical risk factor for carpal tunnel syndrome. This article is protected by copyright. All rights reserved.

The value of sonographic quantitative parameters in the diagnosis of carpal tunnel syndrome in the Vietnamese population

Objective

To examine the value of ultrasound (US) in the diagnosis of carpal tunnel syndrome (CTS) in the Vietnamese population.

Methods

This prospective cross-sectional study involved 42 wrists of 25 patients with idiopathic CTS evaluated by US. In addition, 38 wrists of 22 healthy volunteers were included as the control group.

Results

Significant differences in the median nerve cross-sectional area (CSA) at different levels were found between patients with CTS and controls. Using a cut-off value of 9.5 mm² for the median nerve CSA at the pisiform (p-CSA), US had a sensitivity and specificity of 95.2% and 97.4%, respectively, for the diagnosis of CTS. Area under the curve analysis revealed a sensitivity and specificity of 100% and 95.4%, respectively, for the prediction of severe CTS using a p-CSA of >15.5 mm².

Conclusions

The median nerve CSA is a highly accurate parameter in the diagnosis of CTS. We recommend using a p-CSA of >9.5 mm² as a diagnostic criterion for CTS and a p-CSA of >15.5 mm² as a marker for severe CTS in the Vietnamese population.

Research Registry number: 7261

Review Article "Spotlight on Ultrasonography in the Diagnosis of Peripheral Nerve Disease: The Evidence to Date"

Neuromuscular ultrasound is rapidly becoming incorporated into clinical practice as a standard tool in the assessment of peripheral nerve diseases. Ultrasound complements clinical phenotyping and electrodiagnostic evaluation, providing critical structural anatomical information to enhance diagnosis and identify structural pathology. This review article examines the evidence supporting neuromuscular ultrasound in the diagnosis of compressive mononeuropathies, traumatic nerve injury, generalised peripheral neuropathy and motor neuron disease. Extending the sonographic evaluation of nerves beyond simple morphological measurements has the potential to improve diagnostics in peripheral neuropathy, as well as advancing the understanding of pathological mechanisms, which in turn will promote precise therapies and improve therapeutic outcomes.

The persistent median artery and its vascular patterns: A meta-analysis of 10,394 subjects

The presence of a persistent median artery (PMA) has been implicated in the development of compression neuropathies and surgical complications. Due to the large variability in the prevalence of the PMA and its subtypes in the literature, more awareness of its anatomy is needed. The aim of our meta-analysis was to find the pooled prevalence of the antebrachial and palmar persistent median arteries. An extensive search through the major databases was performed to identify all articles and references matching our inclusion criteria. The extracted data included methods of investigation, prevalence of the PMA, anatomical subtype (antebrachial, palmar), side, sex, laterality, and ethnicity. A total of 64 studies (n = 10,394 hands) were included in this meta-analysis. An antebrachial pattern was revealed to be more prevalent than a palmar pattern (34.0% vs. 8.6%). A palmar PMA was reported in 2.6% of patients undergoing surgery for carpal tunnel syndrome when compared to cadaveric studies of adult patients in which the prevalence was 8.6%. Both patterns of PMA are prevalent in a considerable portion of the general population. As the estimated prevalence of the PMA was found to be significantly lower in patients undergoing surgery for carpal tunnel syndrome than those reported in cadaveric studies, its etiological contribution to carpal tunnel syndrome is questionable. Surgeons operating on the forearm and carpal tunnel should understand the anatomy and surgical implications of the PMA and its anatomical patterns.

Ultrasound-guided peripheral nerve interventions for common pain disorders

There are a number of common pain disorders that can be managed effectively by injections around or ablation of peripheral nerves. Ultrasound is a universally available imaging tool, is safe, cost-effective, and is excellent in imaging many peripheral nerves and guiding needles to the site of the nerves. This article aims to present an overview of indications and techniques of such procedures that can be effectively performed by a radiologist.

Electrodiagnostic, Sonographic, and Clinical Features of Carpal Tunnel Syndrome with Bifid Median Nerve

Purpose

A bifid median nerve (BMN) is not a rare variant. This study aimed to investigate the features of carpal tunnel syndrome (CTS) accompanied by BMN.

Patients and Methods

In this retrospective study, we defined a BMN group as CTS with BMN and a non-bifid median nerve (NMN) group as CTS without BMN. All hands were assigned to four severity grades according to the findings of electrodiagnosis (EDx): very mild, mild, moderate, and severe. The cross-sectional area (CSA) of the median nerve, palmar bowing of the flexor retinaculum, and persistent median artery (PMA) were assessed by ultrasonography. Numerical pain rating scale (NRS) and symptom duration were assessed as clinical variables.

Results

Sixty-four hands (57 patients) and 442 hands (341 patients) were enrolled in the BMN and the NMN groups, respectively. BMN was prevalent in 12.6% of all CTS hands. The distribution of EDx severity grade was milder in the BMN group than in the NMN group (P<0.001). The CSA of the BMN group was 16.2±4.1 mm², slightly larger than 15.1±4.2 mm² in the NMN group (P=0.056). The BMN group showed higher NRS than the NMN group (5.5±1.5 and 4.4±1.7, respectively; P<0.001). In the subgroup analysis, NRS was significantly higher in the BMN group than in the NMN group at all EDx severity grades. In the BMN group, the PMA group showed greater EDx severity (P=0.037) and higher NRS (6.0 and 5.0, respectively; P=0.012) than the non-PMA group. The radial side branch's CSA was larger than that of the ulnar side branch (10.0 mm² and 6.0 mm², respectively; P<0.001).

Conclusion

CTS with BMN presented more severe symptoms and relatively milder EDx severity. When assessing the severity of CTS with BMN, the clinical symptoms should primarily be considered, as well as we should complementarily evaluate the EDx and ultrasonography.

Carpal tunnel syndrome caused by the entrapment of a bifid Lanz IIIA Type anatomical variant of median nerve: A case report and systematic literature review

Background:

Carpal tunnel syndrome (CTS) is the most common entrapment peripheral neuropathy. Median nerve may present several anatomical variations such as a high division or bifid median nerve (BMN). A thorough knowledge of the normal anatomy and variations of the median nerve at the wrist are fundamental to reduce complications during carpal tunnel release.

Case Description:

A 63-year-old man with CTS underwent preoperative ultrasound that showed the entrapment of the median nerve and disclosed a BMN Lanz IIIA Type anatomical variation at the carpal tunnel. During the surgery, the anatomical variant of a BMN at the wrist has been visualized. Both nervous rami entirely occupied the carpal canal and this may have predisposed to the development of the entrapment syndrome. Nor persistent median artery, or other associated abnormalities, have been identified. At the 6 months follow-up control, the patient referred a good surgical recovery with complete resolution of the preoperative symptoms of the median nerve entrapment.

Conclusion:

A rare case of Lanz IIIA BMN Type at the wrist has been encountered in a patient with a CTS and a systematic review and practical considerations have been presented with the aim of raising awareness to the neurosurgical community of a such rare variant that could be encountered during carpal tunnel release procedures. CTS may be caused by the entrapment of a BMN Lanz IIIA Type anatomical variant of median nerve. Preoperative US would help to identify such patients to reduce risk of iatrogenic injuries.

Neuromuscular ultrasound findings in carpal tunnel syndrome with symptoms mainly in the nondominant hand

BACKGROUND

Carpal tunnel syndrome (CTS) may be associated with structural lesions or anatomical variations at the wrist, especially in patients whose symptoms are more severe in, or limited to, the nondominant hand. The aims of this study were to identify the type and frequency of structural abnormalities and anatomical variations, and to demonstrate the contribution of ultrasound in this subgroup of CTS patients.

METHODS

A retrospective chart review was performed on all patients referred to the electromyography laboratory who fulfilled the diagnostic criteria for CTS and who underwent neuromuscular ultrasound.

RESULTS

Of 114 CTS patients with symptoms mainly in nondominant hand, 51 (44.7%) had structural abnormalities or anatomical variations detected by ultrasound. In multivariable analysis, symptoms mainly in the nondominant hand and a body mass index (BMI) <30 kg/m² were the only independent variables significantly associated with structural findings, odds ratios 2.3 (P < .001) and 1.9 (P = .006), respectively.

CONCLUSIONS

Neuromuscular ultrasound, in addition to electrodiagnostic studies, should be considered in all CTS patients with symptoms more severe in nondominant hand as a significant number have abnormal structural abnormalities or anatomical variations that may be causative or change the therapeutic approach.

Managing uncommon and unexpected findings during neuromuscular ultrasound

One barrier to widespread adoption of neuromuscular ultrasound by clinical neurophysiologists is concern over how to identify and manage non-neuromuscular findings. This review addresses this concern by describing the sonographic appearance of a variety of commonly observed pathologies and anatomic variants in dermal, subcutaneous, bony, glandular, lymphatic, vascular, and other superficial tissues. Additionally, it outlines techniques to ensure proper clinical and ultrasound evaluation of unexpected or uncommon findings. Finally, it highlights strategies to manage unexpected findings, including how to best communicate findings to patients and referring clinicians to avoid unnecessary testing and ensure appropriate follow-up. Ultrasound extends the ability of the neuromuscular sonographer-clinician to contribute to patient care.

Ultrasound Findings in Less Frequent Causes of Carpal Tunnel Syndrome

The most common etiology of carpal tunnel syndrome (CTS) is idiopathic. However, secondary causes of CTS should be considered when symptoms are unilateral, or electrodiagnostic studies are discrepant with the clinical presentation. Imaging of the carpal tunnel should be performed when secondary causes of CTS are suspected. An ultrasound evaluation of the carpal tunnel can assess for pathologic changes of the median nerve, detect secondary causes of CTS, and aid in surgical planning.

Clinico-radiological review of peripheral entrapment neuropathies - Part 1 upper limb

PURPOSE

This article aims to review the pertinent anatomy, etiopathogenesis, current clinical and radiological concepts and principles of management in case of upper limb entrapment neuropathies.

METHODS

The review is based on critical analysis of the existing literature as well as our experience in dealing with entrapment neuropathies.

RESULTS

Entrapment neuropathies of the upper limb peripheral nerves are common conditions that are often misdiagnosed because of their varying clinical presentations and lack of standardized diagnostic methods. Clinical assessment and electrodiagnostic studies have been the mainstay; however, imaging techniques have provided newer insights into the pathophysiology of these entities, leading to a paradigm shift in their diagnosis and management. The current best practice protocols for entrapment syndromes are constantly evolving with increasing emphasis on the role high-resolution ultrasound and magnetic resonance imaging. Many imaging criteria are described and we have tried to present the most validated measurements for diagnosing entrapment neuropathies.

CONCLUSION

It is imperative for a clinical radiologist to be familiar with the etiopathogenesis and clinical features of these conditions, in addition to being thorough with the anatomy and the latest imaging strategies.

Persistent median artery inside the carpal tunnel: description and surgical implications

The median artery is usually a transient vessel during the embryonic period. However, this artery can persist in adult life as the persistent median artery. This paper aims to describe this relevant anatomical variation for surgeons, review the literature and discuss its clinical implications. A routine dissection was performed in the upper left limb of a male adult cadaver of approximately 50-60 years of age, embalmed in formalin 10%. The persistent median artery was identified emerging as a terminal branch of the common interosseous artery with a path along the ulnar side of the median nerve. In the wrist, the persistent median artery passed through the carpal tunnel, deep in the transverse carpal ligament. The dissection in the palmar region revealed no anastomosis with the ulnar artery forming the superficial palmar arch. The common digital arteries emerged from the ulnar artery and the persistent median artery. Such variation has clinical and surgical relevance in approaching carpal tunnel syndrome and other clinical disorders in the wrist.

Current and future applications of ultrasound imaging in peripheral nerve disorders

Neuromuscular ultrasound (NMUS) is a rapidly evolving technique used in neuromuscular medicine to provide complimentary information to standard electrodiagnostic studies. NMUS provides a dynamic, real time assessment of anatomy which can alter both diagnostic and management pathways in peripheral nerve disorders. This review describes the current and future techniques used in NMUS and details the applications and developments in the diagnosis and monitoring of compressive, hereditary, immune-mediated and axonal peripheral nerve disorders, and motor neuron diseases. Technological advances have allowed the increased utilisation of ultrasound for management of peripheral nerve disorders; however, several practical considerations need to be taken into account to facilitate the widespread uptake of this technique.

Identification of Aberrant Muscle Bellies in the Carpal Tunnel using Sonography

Musculoskeletal sonography is being widely used for evaluation of structures within the carpal tunnel. While some anatomical variants, such as bifurcated median nerves and persistent median arteries, have been well documented, limited literature describes the sonographic appearance of aberrant muscle bellies within the carpal tunnel. Multiple examples of the sonographic appearance of flexor digitorum superficialis and lumbrical muscle bellies extending into the carpal tunnel are provided. Techniques for static image acquisition and analysis are discussed, and the use of dynamic imaging to confirm which specific muscle belly is involved is described. Knowledge of the potential presence of muscle bellies in these images and ability to identify these structures is vital to avoid misclassification or misdiagnosis as abnormal pathology. The case examples are situated among current published evidence regarding how such anomalies may be related to the development of pathologies, such as carpal tunnel syndrome.

Indications for neuromuscular ultrasound: Expert opinion and review of the literature

Over the last two decades, dozens of applications have emerged for ultrasonography in neuromuscular disorders. We wanted to measure its impact on practice in laboratories where the technique is in frequent use. After identifying experts in neuromuscular ultrasound and electrodiagnosis, we assessed their use of ultrasonography for different indications and their expectations for its future evolution. We then identified the earliest papers to provide convincing evidence of the utility of ultrasound for particular indications and analyzed the relationship of their date of publication with expert usage. We found that experts use ultrasonography often for inflammatory, hereditary, traumatic, compressive and neoplastic neuropathies, and somewhat less often for neuronopathies and myopathies. Usage significantly correlated with the timing of key publications in the field. We review these findings and the extensive evidence supporting the value of neuromuscular ultrasound. Advancement of the field of clinical neurophysiology depends on widespread translation of these findings.

Occurrence of bifid median nerve in healthy and carpal tunnel syndrome patients

We investigated the possible association between median nerve morphology and carpal tunnel size, hand side and nerve conduction measurements. The study included a patient group (n = 58; 44 women) with idiopathic carpal tunnel syndrome (CTS) in 100 hands and a control group of healthy volunteers (n = 56, 112 hands; 44 women). The following data were recorded: (1) median and ulnar motor and sensory nerve conduction parameters (2) ultrasonographic dimensions of the carpal tunnel inlet area (CTA_in) and inlet area of the median nerve. The prevalence of bifid median nerve was 19% in the CTS hands and 13.3% in the control group. Bilateral bifid nerve was detected in 7 subjects and unilateral in 23, with no side or sex preponderance. The median nerve area was larger in the participants with single than those with bifid median nerve. No correlation was found between CTA_in and median nerve area for single or bifid nerves in controls or patients. It was concluded that bifid median nerve was not a rare variation. We could not, however, support its etiological relation to CTS. Ultrasonographic examination of the carpal tunnel region supplementing neurophysiology provided a reliable means to detect median nerve size and morphology.

CLINICAL TRIAL REGISTRATION NUMBER

84; 5/3/15.

Value of oxyneurography, based on near infrared spectroscopy, in the diagnosis of carpal tunnel syndrome in comparison to provocative clinical diagnostic tests and nerve conduction studies

OBJECTIVE

Evaluation of the diagnostic utility of the oxyneurography (ONG) in diagnosing carpal tunnel syndrome (CTS).

METHODS

ONG examination of the median nerve was performed in 260 patients. The results were compared with nerve conduction studies and clinical provocative tests.

RESULTS

ONG index greater than or equal to 62% was found in 95.18% of the patients with no or minimal Nerve Conduction Study (NCS) changes (1-2 according to the Padua classification) but only in 1.69% of the patients with advanced NCS changes (Padua 3-6). The sensitivity and specificity of the ONG study i.e. 95.18% and 98.31%, respectively, were compared with standard clinical tests: Tinel sign (61.45% and 14.69%), Phalen test (34.94% and 45.20%), reverse Phalen test (81.93% and 34.46%) and carpal compression test (91.57% and 72.32%).

CONCLUSIONS

ONG index lower than 62% was indicative of CTS. ONG has higher sensitivity and specificity then other clinical tests and it is an accurate and reliable method for the diagnosis of CTS.

SIGNIFICANCE

Oxyneurography is a non-invasive, fast and safe study which may play role in the diagnosis of carpal tunnel syndrome.

Normal Palmar Anatomy and Variations That Impact Median Nerve Decompression

Annually, carpal tunnel release is one of the most commonly executed orthopaedic procedures. Despite the frequency of the procedure, complications may occur as a result of anatomic variations. Understanding both normal and variant anatomy, including anomalies in neural, vascular, tendinous, and muscular structures about the carpal tunnel, is fundamental to achieving both safe and efficacious surgery. Reviewing and aggregating this information reveals certain principles that may lead to the safest possible surgical approach. Although it is likely that no true internervous plane or so-called safe zone exists during the approach for carpal tunnel release, the long-ring web space axis does appear to pose the lowest risk to important structures.

Sonographic Findings of the Bifid Median Nerve and Persistent Median Artery in Carpal Tunnel: A Preliminary Study in Chinese Individuals

OBJECTIVE:

The aim of this study was to investigate the prevalence of anatomic variations of the bifid median nerve, persistent median artery and persistent median vein in Chinese individuals and their relationship with carpal tunnel syndrome.

METHODS:

One hundred and sixty median nerves were examined using ultrasonography and colour Doppler ultrasonography. The location, shape, and size of the bifid median nerve, persistent median artery and persistent median vein were recorded. The cross-sectional area of the bifid median nerve (two trunks) was measured at the level of the pisiform.

RESULTS:

Among the 160 wrists examined, a bifid median nerve was observed in 15 (9.4%) wrists, and a persistent median artery was observed in 12 (7.5%) wrists. These two variations either coexisted or were observed independently, and the probability of coexistence (6.3%) was higher than the probability of existing independently (bifid median nerve only 3.1%, persistent median artery only 1.3%). The cross-sectional area of the radial trunk was greater than (13 in 15, 86.7%) the cross-sectional area of the ulnaris trunk. Persistent median vein was observed in 9 wrists (5.6%).

CONCLUSIONS:

The persistent median artery and bifid median nerve tend to coexist, and the persistent median vein sometimes runs parallel to the persistent median artery. Their positional relationship in carpal tunnel is uncertain, and thus, preoperative ultrasound is necessary. These three variations do not present any additional risk for the development of carpal tunnel syndrome.

Electrosonodiagnosis in Carpal Tunnel Syndrome: A Proposed Diagnostic Algorithm Based on an Analytic Literature Review

BACKGROUND

Suspected carpal tunnel syndrome (CTS) remains the most common clinical scenario prompting referral for electrodiagnostic (EDx) studies to identify objective correlates of reported subjective symptoms and clinical examination findings. Despite much debate and a rapidly expanding literature, identification of an optimal algorithm for diagnosing focal median mononeuropathy at the wrist (FMMW) associated with CTS signs and symptoms remains elusive. The introduction and rapid dissemination of peripheral nerve ultrasound imaging (PN-USI) of the median nerve has raised new questions regarding the relative value of structural information from PN-USI versus physiological information from EDx in the diagnosis of FMMW, as well as the significance of various clinical signs and symptoms suggestive of CTS. The means by which PN-USI and EDx may be optimally deployed and integrated in the process of diagnosing FMMW remains to be clearly delineated.

OBJECTIVE

To complete an analytical literature review to guide the formulation of a clinical diagnostic algorithm (CDA) integrating the use of PN-USI and EDx for the optimal detection of FMMW in the context of making a clinical diagnosis of CTS.

DATA SOURCES

A structured literature review was performed on the MEDLINE medical literature database accessed through PubMed.

ANALYSIS

Papers with particular relevance and connection to the goal of formulating the CDA were selected from the identified studies. Studies specifically examining the correlations between systematically documented clinical symptomatology, EDx findings, and PN-USI findings were reviewed for consistent outcomes that could be incorporated into a CDA to guide the integration of these two complementary technologies in the diagnostic process.

LIMITATIONS

The formulation of the algorithm was limited to measures with established validity that can be readily obtained by means of widely accepted protocols using standard EDx and ultrasound equipment. The formulated algorithm assumes a consistent association between pathophysiology and anatomical deformation of the median nerve, which may not occur in certain situations. It may also not be as accurately applied to patients with CTS with significant comorbid neuromuscular conditions.

CONCLUSIONS

An algorithm has been developed and presented, and illustrated as a flow chart, based on findings reported in the relevant reviewed literature in which PN-USI is proposed as a painless and rapidly performed screening test for FMMW to be completed before subjecting a patient to a systematic EDx testing process.

Nerve Ultrasound in Peripheral Neuropathies: A Review

Peripheral neuropathies are one of the most common reasons for seeking neurological care in everyday practice. Electrophysiological studies remain fundamental for the diagnosis and etiological classification of peripheral nerve impairment. The recent technological development though of high resolution ultrasound has allowed the clinician to obtain detailed structural images of peripheral nerves. Nerve ultrasound mainly focuses on the evaluation of the cross sectional area, cross sectional area variability along the anatomical course, echogenity, vascularity and mobility of the peripheral nerves. An increase of the cross sectional area, hypervascularity, disturbed fascicular echostructure and reduced nerve mobility are some of the most common findings of entrapments neuropathies, such as the carpal or cubital tunnel syndrome. Both the cross-sectional area increase and the hypervascularity detected with the Doppler technique seem to correlate significantly with the clinical and electrophysiological severity of the later mononeuropathies. Significantly greater cross sectional area values of the clinically affected cervical nerve root are often detected in cases of cervical radiculopathy. In such cases, the ultrasound findings seem also to correlate significantly with disease duration. On the other hand, multifocal cross sectional area enlargement of cervical roots and/or peripheral nerves is often documented in cases of immune-mediated neuropathies. None of the later pathological ultrasound findings seem to correlate significantly with the electrophysiological parameters or the functional disability. The aim of this review is to provide a timely update on the role of neuromuscular ultrasound in the diagnostic of the most common entrapment and immune-mediated peripheral neuropathies in clinical practice.

Persistent median artery thrombosis: A rare cause of carpal tunnel syndrome

Background: Carpal tunnel syndrome (CTS) is a sporadic event with compression of the median nerve (MN). Persistent median artery (PMA) thrombosis is an exceptionally rare cause of CTS. Case report: 38-year-old male presented with acute on subacute right wrist pain with positive Tinel's sign. An ultrasound and computed angiography study confirmed a PMA with thrombosis. The patient was treated with intravenous heparin then discharged home on enoxaparin and warfarin crossover. Discussion: PMA can lead to CTS by compression from the adjacent median nerve. Thrombosis of the PMA can also lead to CTS. Surgical intervention is needed in cases of severe CTS. Carpal tunnel release is usually successful. Excision of the PMA can risk vascular compromise of the digits. Ultrasound is excellent for detecting rare causes of CTS. Conclusion: Ultrasound examination for CTS should include search for PMA and associated anatomical variations.

Carpal tunnel syndrome caused by vascular nerve impairment treated with open release of the carpal tunnel

We present a patient suffering from classical unilateral symptoms of carpal tunnel syndrome, where the results of electrophysiological examinations were negative. Ultrasound showed at pulsatile median artery that led to direct mechanical impact on the median nerve. The patient was successfully treated with open release of the carpal tunnel.

Bifid median nerve in carpal tunnel syndrome: do we need to know?

INTRODUCTION

We tested the hypothesis that a bifid median nerve predisposes to development of carpal tunnel syndrome (CTS) and investigated differences in electrophysiological findings and outcome.

METHODS

A total of 259 consecutive patients with clinically defined CTS were included and investigated clinically, electrophysiologically, and ultrasonographically. Fifty-four healthy asymptomatic volunteers were investigated ultrasonographically.

RESULTS

The prevalence of bifid median nerves is equal in patients with CTS and controls. Electrophysiological and ultrasonographic abnormalities are more pronounced in patients with non-bifid median nerves. Some outcome data are better in patients with non-bifid median nerves, but others do not show significant differences.

CONCLUSIONS

A bifid median nerve is not an independent risk factor for development of CTS. Some of our data suggest outcome after surgical decompression to be different, but others do not. The surgical technique in these patients may therefore have to be reevaluated.