Multimodality imaging review of ulnar nerve pathologies.

The ulnar nerve is the second most commonly entrapped nerve after the median nerve. Although clinical evaluation and electrodiagnostic studies remain widely used for the evaluation of ulnar neuropathy, advancements in imaging have led to increased utilization of these newer / better imaging techniques in the overall management of ulnar neuropathy. Specifically, high-resolution ultrasonography of peripheral nerves as well as MRI has become quite useful in evaluating the ulnar nerve in order to better guide treatment. The caliber and fascicular pattern identified in the normal ulnar nerves are important distinguishing features from ulnar nerve pathology. The cubital tunnel within the elbow and Guyon's canal within the wrist are important sites to evaluate with respect to ulnar nerve compression. Both acute and chronic conditions resulting in deformity, trauma as well as inflammatory conditions may predispose certain patients to ulnar neuropathy. Granulomatous diseases as well as both neurogenic and non-neurogenic tumors can also potentially result in ulnar neuropathy. Tumors around the ulnar nerve can also lead to mass effect on the nerve, particularly in tight spaces like the aforementioned canals. Although high-resolution ultrasonography is a useful modality initially, particularly as it can be helpful for dynamic evaluation, MRI remains most reliable due to its higher resolution. Newer imaging techniques like sonoelastography and microneurography, as well as nerve-specific contrast agents, are currently being investigated for their usefulness and are not routinely being used currently.

Epithelioid malignant peripheral nerve sheath tumour of the ulnar nerve around the elbow: a diagnostic and therapeutic challenge.

Epithelioid malignant peripheral nerve sheath tumour (EMPNST) is a rare histological subtype of malignant peripheral nerve sheath tumour (MPNST), accounting for 5% to 17% of MPNSTs. The clinical and MRI findings of EMPNST mimic those of nerve abscesses, similar to the presentation in Hansen's disease. We present one such case with this kind of diagnostic dilemma. Intraoperative findings suggest a tumour changed the course of management subsequently. The development of neurological deficits postoperatively after tumour resection was a reconstructive challenge. To provide motor power and sensation through a procedure that provides a complete functional outcome for a young patient, distal nerve transfers were chosen. This provided an improvement in the quality of life and hastened the neurological recovery of the involved limb. Level of evidence: V.

PATTERN OF A PRIMARY B-CELL LYMPHOMA IN ULNAR NERVE: INTRANEURAL OR EXTRANEURAL.

Primary lymphomas of peripheral nerves (PLPNs) are extremely rare and most commonly reported in lumbar nerves and have been found in only five cases in the upper extremities. We describe two patterns of presentation focusing on clinical, radiological, and pathological findings of two patients affected by primary multifocal lymphoma of the ulnar nerve without systemic involvement or other medical conditions. We report a case of extraneural lymphoma in a 72-years-old (patient #1) and a case of intraneural lymphoma in a 45-years old woman (Patient #2). Magnetic resonance imaging and ultrasound findings were similar to Peripheral Nerve Sheath Tumors (PNST). Surgical exploration and excision were performed. Morpho pathological results revealed in both cases a diffuse large B-cell non-Hodgkin lymphoma. In patient #1, the disease relapsed after only 4 months with brachial plexus involvement. The patient died about 10 months after the onset of symptoms. Patient #2 did not have post-surgical sensory or motor deficit and follow up at 6 years did not show recurrence or any other localizations. PLPN is a rare and challenging condition and is frequently misdiagnosed. PLPNs could have an intraneural or an extraneural pattern. As peripheral neuropathy may be caused by a nervous involvement by a lymphoma, in patients with atypical lesions, a complete preoperative imaging should be acquired.

Comparison of a Modern Digital Mechanomyograph to a Mechanomyograph Utilizing an Archival Grass Force Transducer.

BACKGROUND: Mechanomyography is the traditional gold standard research technique for quantitative assessment of neuromuscular blockade. Mechanomyography directly measures the isometric force generated by the thumb in response to ulnar nerve stimulation. Researchers must construct their own mechanomyographs since commercial instruments are no longer available. A mechanomyograph was constructed, and its performance was compared against an archival mechanomyography system from the 1970s that utilized an FT-10 Grass force transducer, hypothesizing that train-of-four ratios recorded on each device would be equivalent. METHODS: A mechanomyograph was constructed using 3D-printed components and modern electronics. An archival mechanomyography system was assembled from original components, including an FT-10 Grass force transducer. Signal digitization for computerized data collection was utilized instead of the original paper strip chart recorder. Both devices were calibrated with standard weights to demonstrate linear voltage response curves. The mechanomyographs were affixed to opposite arms of patients undergoing surgery, and the train-of-four ratio was measured during the onset and recovery from rocuronium neuromuscular blockade. RESULTS: Calibration measurements exhibited a positive linear association between voltage output and calibration weights with a linear correlation coefficient of 1.00 for both mechanomyography devices. The new mechanomyograph had better precision and measurement sensitivity than the archival system: 5.3 mV versus 15.5 mV and 1.6 mV versus 5.7 mV, respectively (P < 0.001 for both). A total of 767 pairs of train-of-four ratio measurements obtained from eight patients had positive linear association (R 2 = 0.94; P < 0.001). Bland-Altman analysis resulted in bias of 3.8% and limits of agreement of -13% and 21%. CONCLUSIONS: The new mechanomyograph resulted in similar train-of-four ratio measurements compared to an archival mechanomyography system utilizing an FT-10 Grass force transducer. These results demonstrated continuity of gold standard measurement of neuromuscular blockade spanning nearly 50 yr, despite significant changes in the instrumentation technology.

Myofibroma mimicking peripheral nerve sheath tumour with ulnar nerve compression symptoms.

We report a case of myofibroma encasing the ulnar nerve on the medial aspect of the left arm with motor and sensory deficit secondary to compression. Initially, the tumour appeared to be a benign peripheral nerve sheath tumour based on preoperative imaging, with clinical examination positive for left hand clawing and a positive Wartenberg's and Froment's sign. However, intraoperative dissection demonstrated that the mass did not originate from the ulnar nerve proper, lowering suspicion for a peripheral nerve sheath tumour. Histopathological analysis showed spindle cell neoplasm, consistent with myofibroma. The patient underwent hand occupational therapy subsequently, with improvement of grip strength from 5 lb to 12 lb by 4 months postoperatively and resolution of clawing of the hand postoperatively. We discuss differentiating features for this rare occurrence of solitary adult myofibroma, where the final diagnosis was only made after formal histopathological analysis.

Partial excision of schwannomatosis with fascicular invasion occurring in the ulnar nerve above the elbow: A 1-year follow-up study.

Although not as common as solitary lesions, multiple schwannomas do occur, even in single nerve lesions. We report a rare case of a 47-year-old female patient who presented with multiple schwannomas with inter-fascicular invasion in the ulnar nerve above the cubital tunnel. Preoperative MRI revealed a 10-cm multilobulated tubular mass along the ulnar nerve above the elbow joint. During excision under 4.5° loupe magnification, we separated three ovoid yellow-colored neurogenic tumors of different sizes, but there were still remaining lesions as it was difficult to completely separate lesions from the ulnar nerve due to the risk of iatrogenic nerve ulnar nerve injury. The operative wound was closed. Postoperative biopsy confirmed the diagnosis of the three schwannomas. During the follow-up, the patient recovered without neurological symptom or limitations in range of motion, and there were no neurological abnormalities. At 1year after surgery, small lesions remained in the most proximal part. However, the patient had no clinical symptoms and was satisfied with the surgical results. Although a long-term follow-up is necessary for this patient, we were able to obtain good clinical and radiological results.

[Diagnostic value of F wave changes in patients with Charcot-Marie-Tooth1A and chronic inflammatory demyelinating polyneuropathy].

OBJECTIVE: To analyze and compare the characteristics and causes of F wave changes in patients with Charcot-Marie-Tooth1A (CMT1A) and chronic inflammatory demyelinating polyneuropathy (CIDP). METHODS: Thirty patients with CMT1A and 30 patients with CIDP were enrolled in Peking University Third Hospital from January 2012 to December 2018. Their clinical data, electrophysiological data(nerve conduction velocity, F wave and H reflex) and neurological function scores were recorded. Some patients underwent magnetic resonance imaging of brachial plexus and lumbar plexus, and the results were analyzed and compared. RESULTS: The average motor conduction velocity (MCV) of median nerve was (21.10±10.60) m/s in CMT1A and (31.52±12.46) m/s in CIDP. There was a significant difference between the two groups (t=-6.75, P < 0.001). About 43.3% (13/30) of the patients with CMT1A did not elicit F wave in ulnar nerve, which was significantly higher than that of the patients with CIDP (4/30, 13.3%), χ2=6.65, P=0.010. Among the patients who could elicit F wave, the latency of F wave in CMT1A group was (52.40±17.56) ms and that in CIDP group was (42.20±12.73) ms. There was a significant difference between the two groups (t=2.96, P=0.006). The occurrence rate of F wave in CMT1A group was 34.6%±39%, and that in CIDP group was 70.7%±15.2%. There was a significant difference between the two groups (t=-5.13, P < 0.001). The MCV of median nerve in a patient with anti neurofascin 155 (NF155) was 23.22 m/s, the latency of F wave was 62.9-70.7 ms, and the occurrence rate was 85%-95%. The proportion of brachial plexus and lumbar plexus thickening in CMT1A was 83.3% (5/6) and 85.7% (6/7), respectively. The proportion of brachial plexus and lumbar plexus thickening in the CIDP patients was only 25.0% (1/4, 2/8). The nerve roots of brachial plexus and lumbar plexus were significantly thickened in a patient with anti NF155 antibody. CONCLUSION: The prolonged latency of F wave in patients with CMT1A reflects the homogenous changes in both proximal and distal peripheral nerves, which can be used as a method to differentiate the CIDP patients characterized by focal demyelinating pathology. Moreover, attention should be paid to differentiate it from the peripheral neuropathy caused by anti NF155 CIDP. Although F wave is often used as an indicator of proximal nerve injury, motor neuron excitability, anterior horn cells, and motor nerve myelin sheath lesions can affect its latency and occurrence rate. F wave abnormalities need to be comprehensively analyzed in combination with the etiology, other electrophysiological results, and MRI imaging.

Challenges in diagnosing a peripheral nerve sheath tumor of the ulnar nerve in a dog - a case report.

INTRODUCTION: In this case report we present the rare case of a distally located peripheral nerve sheath tumor (PNST) of the left ulnar nerve in a two-year-old female Rottweiler dog. We discuss the clinical and diagnostic findings and the challenges of the diagnosis. The dog was successfully treated with a limb sparing partial neurectomy. After surgery, the dog did not show any pain or lameness on long term follow-up.

INTRODUCTION: Dans ce rapport de cas, nous présentons le rare cas d'une tumeur périphérique de la gaine du nerf ulnaire/cubital gauche chez une chienne Rottweiler de deux ans. Nous discutons les résultats cliniques et diagnostiques et les défis liés au diagnostic. Le chien a été traité avec succès par une neurectomie partielle. Après la chirurgie, lors du suivi à long terme, le chien n'a plus présenté ni de douleur ni de boiterie.

Epithelioid Hemangioendothelioma in the Area of the Neurovascular Bundle of the Upper Arm Mimicking a Schwannoma of the Ulnar Nerve.

Epithelioid hemangioendothelioma (EH) is a rare vascular malignant sarcoma. To date, there are only two published case reports of EH mimicking nerve sheath tumors of a peripheral nerve. A 41-year-old woman presented with a painful node on the inside of the upper arm and motor deficits of the ulnar nerve. Magnetic resonance imaging (MRI) follow-up and neurosonography revealed a slowly progressive, contrast-enhancing tumor in the area of the neurovascular bundle. A schwannoma of the ulnar nerve was suspected. At surgery, the tumor was adherent to the brachial artery, but not to nerves. Pathology revealed an EH. EH may mimic a nerve sheath tumor and should be taken into consideration, especially because of its potential for metastasis and fatal progression.

Dissection of an Ulnar Nerve Previously Transposed and Wrapped with Human Amniotic Membrane: A Report of 3 Cases.

CASES: We present 3 patients who underwent ulnar nerve transposition and wrapping of the nerve with human amniotic membrane (HAM). All 3 patients subsequently required a reoperation for the original pathologic condition (not for ulnar nerve symptoms), necessitating the exploration and dissection of the transposed ulnar nerve. We demonstrate the lack of scar formation and ease of separation between nerve and surrounding tissue, as well as histology in one case taken from the perineural tissues (previous amniotic membrane), demonstrating no inflammatory cells or absence of scar tissue formation. CONCLUSION: Exploration and dissection of a previously transposed ulnar nerve can be facilitated by wrapping the nerve with HAM to prevent scarring and perineural fibrosis.

Patterns and parameters describing nerve thickening in compression and entrapment ulnar neuropathies at the elbow.

OBJECTIVE: To compare pattern and parameters describing nerve thickening in ulnar neuropathy at the elbow (UNE) due to external compression in the retrocondylar groove (RTC), and entrapment under the humeroulnar aponeurosis (HUA). METHODS: In a group of our previously reported UNE patients we ultrasonographically (US) measured ulnar nerve cross-sectional areas (CSA) on 6-8 standard locations in the elbow segment. We compared CSA patterns in both groups, and determined diagnostic utility of selected CSA based parameters. RESULTS: We studied 79 patients (81 arms) with UNE due to external compression, and 53 patients (55 arms) due to entrapment. Maximal ulnar nerve CSA (>16 mm2), maximal CSA change (>7 mm2/1-2 cm) and maximal/minimal CSA ratio (>2.6) were significantly larger in UNE due to entrapment. They also differentiated these arms from arms with compression with sensitivities of 78%, 87% and 80%, and specificities of 90%, 94%, and 85%, respectively. CONCLUSION: Maximal difference in CSA between points separated by 1-2 cm (>7 mm2/1-2 cm) very efficiently differentiated between UNE due to external compression and entrapment. SIGNIFICANCE: The proposed parameter will hopefully complement precise localization in determining underlying mechanism of UNE. This may help physicians to determine the most appropriate treatment for UNE and possibly other focal neuropathies of unknown cause; i.e., conservative treatment for external compression and surgery for entrapment.

Ulnar nerve subluxation and dislocation: a review of the literature.

The pathogenesis of ulnar nerve subluxation and dislocation is widely debated. Upon elbow flexion, the ulnar nerve slips out of the groove for the ulnar nerve, relocates medial or anterior to the medial epicondyle, and returns to its correct anatomical position upon extension. This chronic condition can cause neuritis or neuropathy; however, it has also been suggested that it protects against neuropathy by reducing tension along the nerve. This article reviews the extant literature with the aim of bringing knowledge of the topic into perspective and standardizing terminology.

Textural markers of ultrasonographic nerve alterations in amyotrophic lateral sclerosis.

Ultrasound has revealed cross-sectional nerve area (CSA) reduction in amyotrophic lateral sclerosis (ALS), but little is known about the sonographic nerve texture beyond CSA alterations. In a large cohort of 177 ALS patients and 57 control subjects, we investigated the covariance and disease-specific signature of several sonographic texture features of the median and ulnar nerves and their relationship to the patients' clinical characteristics. ALS patients showed atrophic nerves, a loss of the intranerve structures' echoic contrast, elevated coarseness, and a trend toward lower cluster shading compared with controls. A reduction in intranerve echoic contrast was related to longer disease duration and poorer functional status in ALS. Sonographic texture markers point toward a significant reorganization of the deep nerve microstructure in ALS. Future studies will be needed to further substantiate the markers' potential to assess peripheral nerve alterations in ALS.

Radiographic characteristics of wrists in idiopathic carpal tunnel syndrome patients.

BACKGROUND: To determine the radiographic characteristics of wrists in idiopathic carpal tunnel syndrome patients, we compared the radiographic parameters of the wrists between carpal tunnel syndrome patients and non-symptomatic controls. METHODS: We evaluated radiographic parameters of 94 wrists of 62 idiopathic carpal tunnel syndrome patients and 94 asymptomatic wrists of 94 controls. Carpal tunnel syndrome was diagnosed by clinical findings and nerve conduction studies. The lack of symptoms was confirmed with the medical records and interviews for the controls. X-ray images of the postero-anterior and lateral views of the wrist were taken. Using the obtained X-ray images, the indices of radial inclination, volar tilt, ulnar variance, and transverse and antero-posterior diameters of the wrists were measured. Two raters independently performed the measurement. One rater measured without information of clinical symptoms. Inter-rater reliabilities for each parameter were evaluated by the intra-class correlation coefficients. The averages of the measurements of two raters were compared between the carpal tunnel syndrome patients and the controls. RESULTS: The intra-class correlation coefficients were 0.58 for radial inclination, 0.77 for ulnar variance, 0.99 for transverse diameter, 0.60 for volar tilt, and 0.91 for antero-posterior diameter. Statistically significant correlations were found for all parameters (P < 0.01). The ulnar variance was significantly larger in the carpal tunnel syndrome patients compared to the controls (1.7 +/- 1.8 mm and 0.8 +/- 1.5 mm for the patients and controls, respectively P < 0.01). There were no significant differences in the other parameters. CONCLUSIONS: Significant differences in the ulnar variance were observed between carpal tunnel syndrome patients and controls. This suggests that the imbalance of radioulnar bone length is one of the risk factors to develop carpal tunnel syndrome. The positive ulnar variance may be an index that needs attention to the development of carpal tunnel syndrome. LEVEL OF EVIDENCE: level III, a case control study.

Modern treatment of perineuriomas: a case-series and systematic review.

BACKGROUND: Perineuriomas are rare benign peripheral nerve sheath tumours of perineurial cell origin and can be classified into intraneural and extraneural perineuriomas. They most commonly present a mononeuropathy of gradual onset and slow progression, resulting in progressive neurological deficits like hypoesthesia or motor weakness. Therapy is still variable. Aim of the study was to compare our surgical treatment and our follow-up regime including high-resolution nerve sonography with the current literature to evaluate best treatment of perineuriomas. METHODS: Retrospective analysis of our dataset "peripheral nerve lesion" to identify patients suffering from perineuriomas between 01.01.2012 until 31.12.2018. Surgical treatment and the follow-up examination of three patients were described. Additionally, a systematic review including PubMed, the Cochrane Collaboration Library, Scopus and Google Scholar was performed for literature published between January 1, 1990 and October 31, 2019 independently by 2 authors. RESULTS: In the first case, the left ulnar nerve was affected. In the second case, the left peroneal nerve and in the third case the right median nerve was affected. High-resolution nerve sonography was performed in each case. All patients underwent interfascicular neurolysis combined with a targeted fascicular biopsy under electrophysiological monitoring. Neurological deficits improved subsidized by rehabilitation. Surgical therapy and the neurological outcome were compared with literature. Systematic review revealed 22 articles, which met the inclusion criteria. Therefore, demographics, surgical treatment and neurological outcome of 77 patients were analysed. CONCLUSIONS: Perineuriomas are rare benign nerve sheath tumours with a slow progression, sometimes difficult to diagnose. Decompression and neurolysis may improve neurological deficits. High resolution nerve sonography might serve as a helpful additional diagnostic tool in this process.

Sleeve-Shaped Neurothekeoma of the Ulnar Nerve: A Unique Case of a Still Unclear Pathological Entity.

Background: Neurothekeomas are slow-growing, well-circumscribed benign neoplasms. They usually involve cutaneous or subcutaneous tissues. Although originally described as myxomas deriving from nerve sheath cells, their exact histological classification is still uncertain. Peripheral nerve localization is rarely reported. Here, we describe a unique case of sleeve-shaped neurothekeoma of the ulnar nerve, which was incidentally discovered during a cubital tunnel release surgery. Methods: A 57-year-old man was admitted at our institution with clinical, ultrasonographic, and electromyographic findings highly suggestive of cubital tunnel syndrome. During ulnar nerve decompression surgery, however, no bony or ligament compression was noticed, but a segment of the nerve wrapped by a thick sleeve-shaped tissue, which had no clear-cut cleavage plane from the nerve. Given this unexpected finding, the en bloc excision of the lesion was avoided. A nerve decompression with biopsy of the swelling portion of the lesion was performed instead. Results: Histological examination described abundant myxoid stroma, with epithelioid and ring-shaped cells arranged in cords, negative to S100 protein at immunohistochemical analysis. This pattern was suggestive of neurothekeoma. The patient showed improvement in hypermyotrophy and intrinsic weakness of the hand. Conclusions: To the best of our knowledge, this is the first report of a sleeve-shaped neurothekeoma of the ulnar nerve. The exact pathological characterization of such rare entities remains uncertain. In case of peripheral nerve localization, and when a clear cleavage plane is absent, the correct management of these lesions should be that of simple nerve decompression followed by biopsy.

Membrane property changes in most distal motor axons in chronic inflammatory demyelinating polyneuropathy.

INTRODUCTION: Distal nerve terminals, where the blood-nerve barrier is anatomically deficient, are preferentially affected in immune-mediated neuropathies. Excitability alterations near the motor nerve terminals may be more prominent than the nerve trunk in typical chronic inflammatory demyelinating polyneuropathy (CIDP). METHODS: In 20 patients with typical CIDP, motor nerve excitability testing was performed at the motor point and wrist of the ulnar nerve, and results were compared with those in 20 healthy persons. RESULTS: Chronic inflammatory demyelinating polyneuropathy patients showed greater threshold changes in hyperpolarizing threshold electrotonus at the motor point (P < .05) but not at the wrist. Strength-duration time constant did not show significant differences between CIDP and controls at both sites. DISCUSSION: Axonal property changes in CIDP are more prominent in distal portions of axons compared with the nerve trunk, presumably due to salient demyelination near the distal nerve terminals. Motor point excitability measurements could elucidate underlying pathophysiology in immune-mediated neuropathies.

Outcomes of revision neurolysis of the ulnar nerve and ulnar groove plasty for persistent and recurrent cubital tunnel syndrome-A retrospective study of 21 cases.

BACKGROUND: Patients undergoing revision surgical treatment of the ulnar nerve at the elbow for cubital tunnel syndrome (CuTS) will have worse results compared to patients successfully treated with primary surgery. OBJECTIVE: The purpose of this study is to evaluated clinical outcomes of revision neurolysis and ulnar groove plasty for recurrent and persistent cubital tunnel syndrome after failed surgical treatment. METHODS: This retrospective investigation included patients presented with recurrent and persistent CuTS who were treated surgically with combination of revision neurolysis and ulnar groove plasty at a single institution from May 2006 to Oct 2016 with postoperative follow-up more than 24 months. Demographic data of all patients including age, sex, months to revision surgery, presenting symptoms after index surgery, previous surgical procedure and intraoperative findings were all recorded and pre-operative and post-operative data were compared. McGowen grading was used to evaluated functional impairment before and after revision surgery. RESULTS: There were 28 patients were identified with recurrent and persistent CuTS after primary surgery and 21 patients (75%) were completed in this study with an average age was 56 years, mean duration of symptoms was 17.24 months, and mean postoperative follow-up was 35.38 months. 17 patients had McGowan stage III and 4 had stage II preoperatively. The most common cause of recurrent and persistent CuTS was perineural fibrosis with or without kink which accounts for 86.36% according to intraoperative findings. McGowan grading improved after revision neurolysis and ulnar groove plasty is 80.95%. Improvement of Visual Analogue Scale (VAS) and 2-point discrimination test were 81.25% and 85.71%, respectively. Patients satisfaction after revision neurolysis and ulnar groove plasty was 95.24%. CONCLUSION: The favorable results of this study demonstrated that revision neurolysis and ulnar groove plasty as the treatment of choice for recurrent or persistent cubital tunnel syndrome.