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.

[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.

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.

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.

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.

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.

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.

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.

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.

Multiple intraneural glomus tumors in different digital nerve fascicles.

BACKGROUND: Glomus tumors in the digital nerve are extremely rare. Multiple intraneural glomus tumors in different digital nerve fascicles have not been previously reported. CASE PRESENTATION: We report the case of a 54-year-old male with a 1-year history of progressive numbness of the middle finger with point tenderness at the level of the middle phalanx. Surgical incision revealed the presence of two glomus tumors within different fascicles of the ulnar digital nerve of the middle finger. One tumor was excised along with surrounding fascicle, the other was removed leaving the fascicle intact. Subsequently, the patient regained function of the finger and no tumors have recurred. CONCLUSIONS: Patients and physicians should be aware of the properties of intraneural glomus tumors so that early diagnosis and treatment can be sought.

Prevalence of carpal tunnel syndrome presenting with symptoms in an ulnar nerve distribution: A prospective study.

INTRODUCTION: Patients presenting with symptoms of pain/paresthesias primarily in an ulnar nerve distribution may be noted to have exclusive median mononeuropathy at the wrist on subsequent electrodiagnostic testing. There has been limited research looking at the prevalence of this clinical presentation. METHODS: A cohort of adults were surveyed to assess for severity and localization of hand symptoms using the Katz hand diagram and Boston Carpal Tunnel Questionnaire Symptoms Severity Scale. Thirty volunteers met our case definition for ulnar neuropathy and underwent a standardized physical examination, electrodiagnostic testing, and nerve ultrasound. RESULTS: Eleven of 30 subjects (37%) were found to have exclusive median mononeuropathy at the wrist. DISCUSSION: Carpal tunnel syndrome should remain high on the differential for patients presenting with symptoms of pain/paresthesias primarily in an ulnar nerve distribution. Muscle Nerve 59:60-63, 2019.

Toward in vivo determination of peripheral nervous system immune activity in amyotrophic lateral sclerosis.

INTRODUCTION: We sought to identify patients with amyotrophic lateral sclerosis (ALS) who displayed suspected peripheral nervous system (PNS) inflammation to compare them to those with suspected PNS degeneration. METHODS: We measured sonographic median and ulnar nerve cross-sectional area (CSA) and cerebrospinal fluid albumin/serum albumin ratio (Qalb ) in patients with ALS to classify them as having suspected PNS degeneration (small CSA/low Qalb ) or inflammation (larger CSA/high Qalb ). RESULTS: Fifty-seven percent of patients had suspected PNS degeneration, 21% had suspected PNS inflammation, and 21% displayed suspected "normal PNS state." Suspected PNS degeneration was related to classic ALS, shorter disease duration, and a smaller hypoechoic nerve area. Suspected PNS inflammation was associated with men, longer disease duration, and a larger hypoechoic nerve area and was the dominant finding in superoxide dismutase 1 mutation carriers. DISCUSSION: Our simple approach might aid in the in vivo differentiation of supposed ALS subtypes, those with suspected PNS degeneration vs. inflammation, for stratification in clinical trials. Muscle Nerve 59:567-567, 2019.

Nerve size correlates with clinical severity in Charcot-Marie-Tooth disease 1A.

INTRODUCTION: Nerve cross-sectional area (CSA) is larger than normal in Charcot-Marie-Tooth disease 1A (CMT1A), although to a variable extent. We explored whether CSA is correlated with CMT clinical severity measured with neuropathy score version 2 (CMTNS2) and its examination subscore (CMTES2) in CMT1A. METHODS: We assessed 56 patients with CMT1A (42 families). They underwent nerve conduction study (NCS) and nerve high-resolution ultrasound (HRUS) of the left median, ulnar, and fibular nerves. RESULTS: Univariate analysis showed NCS and HRUS variables to be significantly correlated with CMTNS2 and CMTES2 and with each other. Multivariate analysis showed that ulnar motor nerve conduction velocity (ß: -0.19) and fibular compound muscle action potential amplitude (-1.50) significantly influenced CMTNS2 and that median forearm CSA significantly influenced CMTNS2 (ß: 5.29) and CMTES2 (4.28). DISCUSSION: Nerve size is significantly associated with clinical scores in CMT1A, which suggests that it might represent a potential biomarker of CMT damage and progression.

Ultrasound Parameters Other Than the Direct Measurement of Ulnar Nerve Size for Diagnosing Cubital Tunnel Syndrome: A Systemic Review and Meta-analysis.

OBJECTIVE: To investigate the diagnostic performance of available ultrasound (US) parameters, other than the direct measurements of ulnar nerve size, that is, cross-sectional area (CSA) and diameter, for diagnosing cubital tunnel syndrome (CuTS). DATA SOURCES: Databases, including PubMed and Embase, were searched from the earliest record of CuTS US to April 24, 2018. STUDY SELECTION: Published studies (N=13) comparing US parameters of ulnar nerves between patients with CuTS and patients without CuTS were included. DATA EXTRACTION: Study design, participants' demographics, diagnostic references of CuTS, and US parameters other than the direct measurements of the ulnar nerve size were retrieved from the included studies. DATA SYNTHESIS: This systematic review comprised 663 CuTS patients and 543 patients without CuTS. The pooled nerve swelling ratio in the CuTS group was significantly larger than that of the controls. The mean between-group differences of CSAMax or ME/CSAarm, CSAMax or ME/CSAforearm and CSAMax or ME/CSAwrist were 1.03 (95% confidence interval [CI], 0.77-1.29), 1.38 (95% CI, 0.93-1.82), and 0.83 (95% CI, 0.56-1.11), respectively. Regarding the swelling ratio of CSAMax or ME /CSAarm, the pooled sensitivity and specificity available from the 3 included studies were 0.67 (95% CI, 0.59-0.74) and 0.81 (95% CI, 0.75-0.86), respectively. Similarly, for the swelling ratio of CSAMax or ME/CSAforearm, the pooled sensitivity and specificity were 0.62 (95% CI, 0.54-0.69) and 0.86 (95% CI, 0.81-0.90), respectively. Other US parameters identified in this review included nerve-flattening ratio (maximum diameter/minimum diameter), nerve-to-tunnel ratio (ulnar nerve CSA/cubital tunnel CSA), nerve echogenicity, and intraneural vascularity, all of which were reported in a minority of included articles. CONCLUSIONS: Despite the insufficient number of pertinent studies to prove its superiority to other US measurements, the ulnar nerve-swelling ratio can be a complementary tool for diagnosing CuTS. The presence of intraneural vascularity, increased flattening ratio, and enlarged intraneural hypoechoic fraction also seem to be potential US indicators for CuTS diagnosis, which need to be validated with more prospective studies.

Ratio and difference of the cross-sectional area of median nerve to ulnar nerve in diagnosing carpal tunnel syndrome: a case control study.

BACKGROUND: To evaluate the diagnostic accuracy of the median-to-ulnar nerve ratio (MUR) and the median-to-ulnar nerve difference (MUD) in patients with carpal tunnel syndrome (CTS). METHODS: In this study, 32 patients with CTS and 32 healthy volunteers were evaluated. All participants received a series of tests and ultrasound examination for the evaluation of the following criteria: cross-sectional area of the median nerve at the pisiform level (CSA-P), swelling ratio (SR), MUR, MUD, and flattening ratio (FR). RESULTS: CSA-P, SR, MUR, and MUD were all significantly larger in the patients with CTS than in the healthy volunteers. The areas under the receiver operator characteristic curves of MUD, MUR, CSA-P, and SR were 0.78, 0.75, 0.70, and 0.61 respectively. MUD had higher sensitivity (84%) than MUR, CSA-P, and SR (sensitivity: 63, 63, and 53%, respectively). CONCLUSIONS: By using the ulnar nerve area at the pisiform level as an internal control parameter, the MUD and MUR methods showed higher diagnostic accuracy than SR in patients with CTS. Further application of these methods in research and clinical settings is recommended. TRIAL REGISTRATION: Clinicaltrial.gov NCT03033173. Registered 18 January 2017. Retrospectively registered.

Neuritic Leprosy; An Intriguing Re-visit to a Forbidden Ailment.

Leprosy is a chronic infectious disease that presents with varied manifestations. Pure neuritic leprosy is one of the rarest forms of the disease which is characterized by nerve involvement without the characteristic cutaneous stigmata. Eleven year old, healthy male presented with progressively increasing painful swelling at the medial aspect of the arm near to the right elbow joint with difficulty in extending right ring and little fingers at interphalangeal joint and numbness in the same region for last 1 year with no cutaneous abnormalities. Physical examination revealed 6x3 cm firm, tender lesion 3 cm proximal to the right elbow joint with positive tinel's sign, without signs of inflammation, along with characteristic claw hand deformity of right hand and atrophy of hypothenar and interossei muscle. Electro-diagnostic testing revealed findings consistent with a right ulnar axonal neuropathy above the elbow. Magnetic resonance imaging revealed well defined heterogeneously hyper intense linear lesion along the course of thickened ulnar nerve in the distal arm extending posterior to the medial condyle. It also showed an oval shaped lesion (2.1x1.0 cm) arising from the same segment of the nerve, without any bony or muscular involvement of that area. The patient underwent surgical exploration and ulnar nerve decompression with biopsy. Pathology revealed necrotizing granulomatous inflammatory acid fast bacilli stain negative lesion, which was histologically consistent with caseous abscess caused by tuberculoid leprosy, pathognomonic for Hansen's disease. He has been started on antibiotic therapy and is referred to leprosy center for further course of management. Pure neuritic leprosy, though rare, should be considered as differential diagnosis in cases presenting with peripheral neuropathy at leprosy-endemic areas. Prompt diagnosis and treatment is imperative to prevent permanent neurological injury.

The cubital tunnel syndrome caused by intraneural ganglion cyst of the ulnar nerve at the elbow: a case report.

BACKGROUND: Cubital tunnel syndrome is common nerve compression syndrome among peripheral nerve compression diseases. However, the syndrome caused by intraneural ganglion cysts has been rarely reported. Medical approaches, like ultrasound-guided aspiration and open surgical treatment remain to be discussed. CASE PRESENTATION: A 57-year-old woman presented with occasional pain, numbness and paralysis in her left hand and a palpable, painless mass in the ulnar side of her left elbow. Ultrasound-guided aspiration of the mass was performed to decompress the ulnar nerve. The patient experienced an evident release of pain in her hand, but symptoms of numbness and paralysis recurred 3 months later which greatly bothered the patient's daily life. After evaluation, we had to perform an open surgery to excise the cyst. External neurolysis and anterior subcutaneous transposition were done. The patient was followed up for 2 years, and she made a complete recovery with no functional limitation. CONCLUSIONS: The symptoms caused by intraneural ganglion cyst can be alleviated by accurate puncture. But puncture may be not complete and symptoms could recur. Complete external neurolysis can be counted as a complete and reliable treatment. Therefore, early diagnosis, careful preoperative imaging assessment and full decompression can be expected to receive a good rehabilitation.

An anatomical study of so-called fibrous bands around the ulnar nerve distal to the cubital tunnel.

BACKGROUND: Fibrous bands (FB) are structures that cross the ulnar nerve (UN), distal to the cubital tunnel (CT). In surgical decompression of the UN in the elbow region, by endoscopy, these FB significantly impact UN visibility. The aim of the current study was to characterize the anatomical characteristics of these FB distal to the CT. METHODOLOGY: Eighteen formalinized upper limbs were dissected, nine right and nine left, within the Department of Anatomy of the Federal University of the State of Rio de Janeiro (UNIRIO). The dissections were performed with micro techniques, under a magnifying glass and a microscope. Classical UN exposure was established in the elbow region. RESULTS: Of the 18 upper limbs studied, 50% lacked any FB. When present, both the number and location of the FB varied, as near to the cubital tunnel as 3 cm past the UN's entrance into the tunnel, and as far away as almost 11 cm distal to it. Overall, there were no FB on either the left or right side in three cadavers (33.3%), FB on both the left and right side in three, and FB only on the left in three, meaning that FB were twice as common in left limbs (n = 6) as on the right (n = 3). CONCLUSIONS: Our study identified FB in 50% of the dissected limbs, all within 3-11 cm of the CT, though their number and location varied. Further studies are necessary to describe FB variations associated with compressive neuropathies of the UN distal to the CT.

Diffusion-weighted MR neurography of median and ulnar nerves in the wrist and palm.

OBJECTIVES: To investigate the feasibility of diffusion-weighted magnetic resonance neurography (DW-MRN) in the visualisation of extremity nerves in the wrist and palm. METHODS: Thirty-two volunteers and 21 patients underwent imaging of the wrist and palm on a 3-T MR scanner. In all subjects, two radiologists evaluated the image quality on DW-MRN using a four-point grading scale. Kappa statistics were obtained for inter-observer performance. In volunteers, the chi-squared test was used to assess the differences in nerve visualisation on DW-MRN and axial fat-suppressed proton density weighted imaging (FS-PDWI). RESULTS: In volunteers, the mean image quality scores for the median nerve (MN) and ulnar nerve (UN) were 3.71 ± 0.46 and 3.23 ± 0.67 for observer 1, and 3.70 ± 0.46 and 3.22 ± 0.71 for observer 2, respectively. The inter-observer agreement was excellent (k = 0.843) and good (k = 0.788), respectively. DW-MRN provided significantly improved visualisations of the second and the third common palmar digital nerves and three branches of UN compared with FS-PDWI (P < 0.05). In patients, the mean image quality scores for the two observers were 3.24 ± 0.62 and 3.10 ± 0.83, inter-observer performance was excellent (k = 0.842). CONCLUSIONS: DW-MRN is feasible for improved visualisation of extremity nerves and their lesions in the wrist and palm with adequate image quality, thereby providing a supplementary method to conventional MR imaging. KEY POINTS: • DW-MRN provides adequate image quality for wrist and palm neurography • DW-MRN performs similarly to FS-PDWI in nerve visualisation at the wrist • DW-MRN provides improved visualisation of small nerves in the palm • DW-MRN serves as a supplementary method to evaluate peripheral neuropathies.

Use of High-Resolution Ultrasonography in Anterior Subcutaneous Transposition of the Ulnar Nerve for Cubital Tunnel Syndrome.

OBJECTIVES: Cubital tunnel syndrome (CTS) is the most common form of ulnar nerve entrapment. In this study, ultrasonography (US) was used not only for diagnosis but also for operation. US findings could be used to establish the diagnosis of CTS and could demonstrate the pathological anatomy in the cubital tunnel region to guide anterior subcutaneous transposition of the ulnar nerve. METHODS: Sixty-two patients with clinical and electrophysiological evidence of ulnar nerve entrapment were included. All patients received ultrasonographic examination and anterior subcutaneous transposition of the ulnar nerve. The maximal diameter of the ulnar nerve (MDU) was measured in longitudinal views and the range of the hypoechoic area around the nerve was observed. The cross-sectional area (CSA) was also measured on transverse scans. The actual MDU was measured during operation. RESULTS: The actual MDU was 6.4 ± 0.4 mm, measured during operation. The preoperative MDU was 3.1 ± 0.2 mm. The MDU values recorded in CTS patients were greater than those in normal subjects. The range of the hypoechoic area observed on longitudinal US scans was 2.9-5.6 mm (mean, 4.1 ± 0.4 mm). CONCLUSIONS: High-resolution US can be used not only in the diagnosis of CTS, also for providing effective preoperative evaluation for the anterior subcutaneous transposition of the ulnar nerve in CTS.