The utility of segmental nerve conduction studies in ulnar mononeuropathy at the elbow

Electrodiagnostic studies and new diagnostic modalities for evaluation of peripheral nerve disorders

Electrodiagnostic studies (EDx) are frequently performed in the diagnostic evaluation of peripheral nerve disorders. There is increasing interest in the use of newer, alternative diagnostic modalities, in particular imaging, either to complement or replace established EDx protocols. However, the evidence to support this approach has not been expansively reviewed. In this paper, diagnostic performance data from studies of EDx and other diagnostic modalities in common peripheral nerve disorders have been analyzed and described, with a focus on radiculopathy, plexopathy, compressive neuropathies, and the important neuropathy subtypes of Guillain-Barré syndrome, chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), vasculitic neuropathy and diabetic neuropathy. Overall EDx retains its place as a primary diagnostic modality in the evaluated peripheral nerve disorders. Magnetic resonance imaging and ultrasound have developed important complementary diagnostic roles in compressive and traumatic neuropathies and atypical CIDP, but their value is more limited in other neuropathy subtypes. Identification of hourglass constriction in nerves of patients with neuralgic amyotrophy may have therapeutic implications. Investigation of radiculopathy is confounded by poor correlation between clinical features and imaging findings and the lack of a diagnostic gold standard. There is a need to enhance the literature on the utility of these newer diagnostic modalities.

The role of electrodiagnosis in focal neuropathies

Electrodiagnostic (EDX) testing plays an important role in confirming a mononeuropathy, localizing the site of nerve injury, defining the pathophysiology, and assessing the severity and prognosis. The combination of nerve conduction studies (NCS) and needle electromyography findings provides the necessary information to fully assess a nerve. The pattern of NCS abnormalities reflects the underlying pathophysiology, with focal slowing or conduction block in neuropraxic injuries and reduced amplitudes in axonotmetic injuries. Needle electromyography findings, including spontaneous activity and voluntary motor unit potential changes, complement the NCS findings and further characterize chronicity and degree of axon loss and reinnervation. EDX is used as an objective marker to follow the progression of a mononeuropathy over time.

Ulnar neuropathy

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

Diagnostic Considerations in Compressive Neuropathies

Peripheral nerve compression of the upper extremity is a common pathology often necessitating surgical intervention, much is known, but much more is left to understand. For the more common pathologies, carpal tunnel syndrome, cubital tunnel syndrome, and ulnar tunnel syndrome, research and clinical efforts directed toward standardization and reduction of resource use have been attempted with varied success. Diagnosis of many of these syndromes is largely based on a proper history and physical examination. Electrodiagnostic studies continue to have value, but proportionally less than previous decades. In addition, emerging technologies, including magnetic resonance neurography, novel ultrasound evaluation techniques, and ultrasound-guided diagnostic injections, are beginning to demonstrate their ability to add value to the diagnostic algorithm, particularly when less common compressive neuropathies are present and/or the diagnosis is in question.

Classifying the Severity of Cubital Tunnel Syndrome: A Preoperative Grading System Incorporating Electrodiagnostic Parameters

BACKGROUND

Current classifications for cubital tunnel syndrome have not been shown to reliably predict postoperative outcomes. In this article, the authors introduce a new classification that incorporates clinical and electrodiagnostic parameters, including compound muscle action potential amplitude, to classify the preoperative severity of cubital tunnel syndrome. The authors compare this to established classifications and evaluate its association with patient-rated improvement.

METHODS

The authors reviewed 44 patients who were treated surgically for cubital tunnel syndrome. Patients were retrospectively classified using their proposed classification and the Akahori, McGowan-Goldberg, Dellon, and Gu classifications. Correlation of grades was assessed by Spearman coefficients and agreement was assessed by weighted kappa coefficients. Patient-reported impairment was assessed using the Disabilities of the Arm, Shoulder, and Hand questionnaire before and after surgery.

RESULTS

The classifications tended to grade patients in a similar way, with Spearman coefficients of 0.60 to 0.85 ( p < 0.0001) and weighted kappa coefficients of 0.46 to 0.71 ( p < 0.0001). Preoperative Disabilities of the Arm, Shoulder, and Hand scores increased with severity grade for most classifications. In multivariable analysis, the authors' classification predicted postoperative Disabilities of the Arm, Shoulder, and Hand score improvement, whereas established classifications did not.

CONCLUSIONS

Established classifications are imperfect indicators of preoperative severity. The authors introduce a preoperative classification for cubital tunnel syndrome that incorporates electrodiagnostic findings in addition to classic signs and symptoms.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Diagnostic, III.

A retrospective study of electrodiagnostically evaluated ulnar neuropathies with special guidelines for ulnar neuropathies at elbow

Background

The diagnosis of type, severity of ulnar neuropathy based on symptoms and clinical tests are unsatisfactory. This study aimed to retrospectively analyze ulnar neuropathies at different sites evaluated through electrodiagnostic studies (EDx), especially for ulnar neuropathy at elbow (UNE).

Results

Total 270 ulnar neuropathy patients’ data were recruited from laboratory record over a five-year period (2016–2021).Their demographic data, clinical history and EDx parameters were analyzed focusing on etiology, nerve lesion types, 5th-digit sensory, dorsal ulnar cutaneous nerve (DUCN) conduction, motor nerve conduction velocity (NCV) across elbow along with EMG of ADM, FDI, FCU, FDP muscles. The patients grouped into traumatic injuries—27.8% (T) and 72.2% non-traumatic (NT) had varied sensory-motor symptoms: pain—10%, altered sensation—28.1%, pain-paresthesia—14.8%, atrophy—25.2% and clawing—8.9%. UNE was the most prevalent (82.75%-NT, 66.67% -T) with < 50 m/s motor and sensory NCV across elbow. Compound muscle action potential (CMAP) amplitude > 50% drop across elbow was seen in 55.17%-NT and 54.16%-T groups. Abnormal DUCN and short-segment inching NCV were less frequently noted. In EMG, ADM (T-83.33% and NT-65.51%) and FDI (T-70.83% and NT-68.96%) muscles were evaluated the most and FDP the least.

Conclusion

UNE was the most common followed by forearm and wrist. NCV and CMAP across elbow are stronger EDx parameters for UNE. Neuropathy was irrespective of gender and prevalent at early of middle age. The EDx could be considered as one of the most valuable tests in confirming the localization, severity and type of ulnar nerve lesion, which favors management and prognosis of patient.

Electromyography Case Examples: Practical Approaches to Neuromuscular Symptoms

Many neuromuscular complaints are evaluated with electrodiagnostic testing. In practice, physicians must plan the electrodiagnostic study to provide the most useful information addressing patients' symptoms. The approach to each study must be individualized based on the symptoms and findings of each previous result. This article reviews five real cases with common reasons for referral to the neurophysiology laboratory with discussion of the approach to testing, interpretation of the results, and practical decision-making points relevant to each case. The goal is to provide rationale for why specific studies were selected and how each was helpful in deriving the final diagnosis.

Determining the utility of minimum F-wave latency alterations in the electrodiagnosis of ulnar neuropathy at the elbow

BACKGROUND

Ulnar neuropathy at the elbow (UNE) is the second most common entrapment neuropathy. There is little information about the application of F-wave studies for evaluation of UNE.

OBJECTIVE

The aim of this study was to evaluate the diagnostic value of minimum F-wave (F-min) latency alterations by comparing this with nerve conduction analyses in UNE-suspected patients.

METHODS

Ninety-four UNE-suspected patients were admitted to this study. Sensory and motor nerve conduction and F-wave analyses on the median and ulnar nerves were performed on both upper extremities.

RESULTS

A total of 188 upper extremities of 94 patients were examined. Their mean age was 41.4±12.9 years, and 69 patients were female (73.4%). The mean ulnar-nerve across-elbow motor conduction velocity (MCV) in the affected arms was significantly slower than the velocity in healthy arms. The mean ulnar-nerve F-min latencies were significantly longer in the affected arms. Fifty-one patients were electrophysiologically diagnosed as presenting UNE (54.2%). Significantly slower mean ulnar-nerve across-elbow MCV, longer mean ulnar-nerve F-min latency and longer distal onset latency were detected in UNE-positive arms. Lastly, patients who were symptomatic but had normal nerve conduction were evaluated separately. Only the mean ulnar F-min latency was significantly longer in this group, compared with the healthy arms.

CONCLUSION

Our study confirmed the utility of F-min latency measurements in the electrodiagnosis of UNE. F-wave latency differences can help in making an early diagnosis to provide better treatment options.

Comparison of electrodiagnosis, neurosonography and MR neurography in localization of ulnar neuropathy at the elbow

INTRODUCTION

In patients with ulnar neuropathy at the elbow (UNE) the precise determination of the site of lesion is important for subsequent differential diagnostic considerations and therapeutic management. Due to a paucity of comparable data, to better define the role of different diagnostic tests, we performed the first prospective study comparing the diagnostic accuracy of short segment nerve stimulation, nerve ultrasonography, MR neurography (MRN), and diffusion tensor imaging (DTI) in patients with UNE.

METHODS

UNE was clinically diagnosed in 17 patients with 18 affected elbows. For all 18 affected elbows in patients and 20 elbows in 10 healthy volunteers, measurements of all different diagnostic tests were performed at six anatomical positions across the elbow with measuring points from distal (D4) to proximal (P6) in relation to the medial epicondyle (P0). Additional qualitative assessment regarding structural changes of surrounding nerve anatomy was conducted.

RESULTS

The difference between affected arms of patients and healthy control arms were most frequently the largest at measure intervals D2 to P0 and P0 to P2 for electrophysiological testing, or measure points P0 and P2 for all other devices, respectively. At both levels P0 and at P2, T2 contrast-to-noise ratio (CNR) of MRN and mean diffusivity (MD) of DTI-based MRN showed best accuracies.

DISCUSSION

This study revealed differences in diagnostic performance of tests concerning a specific location of UNE, with better results for T2 contrast to noise ratio (CNR) in MRN and mean diffusivity of DTI-based MRN. Additional testing with MRN and nerve ultrasonography is recommended to uncover anatomical changes.

The needle electromyography findings in the neurophysiological classification of ulnar neuropathy at the elbow

Background/aim

Although ulnar neuropathy at the elbow (UNE) is the second most common entrapment mononeuropathy, there are few reports on its neurophysiological classification. In this study, we tried to find out the role of needle electromyography (EMG) in the neurophysiological classification of UNE.

Materials and methods

UNE patients who met the clinical and neurophysiological diagnostic criteria and healthy individuals were included in this study. Reference values of nerve conduction studies were obtained from healthy individuals. Needle EMG was performed to all UNE patients. According to the neurophysiological classification proposed by Padua, UNE patients were classified as mild, moderate, and severe.

Results

Thirty-one controls and thirty-five UNE patients were included in the study. There was mild UNE in 23 patients, moderate UNE in 8, and severe UNE in 4. Abnormal needle EMG findings were present in all patients with moderate and severe UNE and in 12 patients with mild UNE.

Conclusion

Abnormal needle EMG findings are seen in most of the UNE patients. Therefore, it is not practical to use needle EMG findings in the neurophysiological classification. Needle EMG abnormalities may also be present in patients with mild UNE due to axonal degeneration or motor conduction block.

Clinical Findings and Electrodiagnostic Testing in Ulnar Neuropathy at the Elbow and Differences According to Site and Type of Nerve Damage

OBJECTIVE

The aim of the study was to evaluate the clinical and electrodiagnostic testing in ulnar neuropathy at the elbow and differences according to site (humeroulnar arcade vs. retroepicondylar groove) and injury physiopathology (axonal vs. demyelinating), through prospective multicenter case-control study.

DESIGN

Cases and controls were matched by age and sex. Ulnar neuropathy at the elbow diagnosis was made on symptoms. Statistical analysis was performed using Mann-Whitney, χ, and analysis of variance tests.

RESULTS

One hundred forty-four cases and 144 controls were enrolled. Sensory loss in the fifth finger had the highest sensitivity (70.8%) compared with clinical findings. Motor conduction velocity across elbow reached the highest sensitivity (84.7%) in localizing ulnar neuropathy at the elbow recording from at least one of the two hand muscles (first dorsal interosseous and abductor digiti minimi). Abnormal sensory action potential amplitude from the fifth finger occurred more frequently in axonal than in demyelinating forms. Differences between retroepicondylar groove and humeroulnar arcade regarded conduction block and job type.

CONCLUSIONS

Clinical findings have less usefulness than electrodiagnostic testing in ulnar neuropathy at the elbow diagnosis. Motor conduction velocity across elbow recorded from both abductor digiti minimi and first dorsal interosseous increases diagnostic accuracy. Axonal forms have greater clinical and electrodiagnostic testing severity than demyelinating forms, which are more frequent in retroepicondylar groove. Manual workers prevailed in humeroulnar arcade. These findings may be helpful in prognostic and therapeutic approaches.

Short segment sensory nerve stimulation in suspected ulnar neuropathy at the elbow: A pilot study

INTRODUCTION

Routine ulnar nerve conduction studies may be normal in very mild ulnar neuropathies at the elbow (UNE). Short segment ulnar sensory stimulation across the elbow may detect mild abnormalities in these cases.

METHODS

Short segment ulnar sensory nerve stimulation was performed in 20 controls and 15 patients with clinically suspected mild UNE. Greatest peak latency shift and amplitude drop between 2 adjacent stimulation sites were calculated.

RESULTS

The upper limit of normal for peak latency shift and amplitude reduction between sites was 0.7 ms and 15%, respectively. Abnormal latency shift was detected in 12 of 15 patients and focal sensory conduction block in 6 of 15 patients. In 5 of 7 patients in whom all other studies were normal, sensory inching was abnormal.

DISCUSSION

Ulnar sensory short segment stimulation may provide diagnostic confirmation and localization of the site of nerve compression in mild UNE, and may improve UNE detection when all other studies are normal. Muscle Nerve 59:125-129, 2019.

Two novel methods to assess ulnar nerve conduction across the elbow

PURPOSE

Nerve conduction studies (NCS) are used as an electrodiagnostic method for diagnosing ulnar neuropathy of the elbow (UNE). The purpose of this study was to determine normal and reliability values of across elbow ulnar nerve conduction velocity using two novel methods.

METHODS

Ulnar nerve conduction studies were performed on both upper extremities of 104 healthy subjects. Two different techniques were used to evaluate ulnar nerve function at the elbow: Technique 1 (W-BE-AE) determined mixed NCV across the elbow indirectly while Technique 2 (BE-AE) measured conduction time directly. Twenty subjects returned within one week for re-testing to generate reliability data.

RESULTS

The mean NCV for the BE-AE segment using Technique 1 was 59.68m/s (±8.91m/s). The mean peak latency for the BE-AE segment using Technique 2 was 2.03ms (±0.24ms). The interrater and intrarater reliability intraclass correlation coefficient (ICC) for Technique 1 was 0.454 and 0.756, respectively. For Technique 2, the interrater and intrarater reliability ICC was 0.76 and 0.814, respectively.

CONCLUSION

This study identified normal values for ulnar nerve conduction across the elbow with reliability ranging from poor to good, depending on the technique. These two novel techniques provide alternative methods to traditional techniques to measure ulnar nerve conduction across the elbow.

Preliminary study on the lesion location and prognosis of cubital tunnel syndrome by motor nerve conduction studies

Background:

To study lesions’ location and prognosis of cubital tunnel syndrome (CubTS) by routine motor nerve conduction studies (MNCSs) and short-segment nerve conduction studies (SSNCSs, inching test).

Methods:

Thirty healthy subjects were included and 60 ulnar nerves were studied by inching studies for normal values. Sixty-six patients who diagnosed CubTS clinically were performed bilaterally by routine MNCSs and SSNCSs. Follow-up for 1-year, the information of brief complaints, clinical symptoms, and physical examination were collected.

Results:

Sixty-six patients were included, 88 of nerves was abnormal by MNCS, while 105 was abnormal by the inching studies. Medial epicondyle to 2 cm above medial epicondyle is the most common segment to be detected abnormally (59.09%), P < 0.01. Twenty-two patients were followed-up, 17 patients’ symptoms were improved. Most of the patients were treated with drugs and modification of bad habits.

Conclusions:

(1) SSNCSs can detect lesions of compressive neuropathy in CubTS more precisely than the routine motor conduction studies. (2) SSNCSs can diagnose CubTS more sensitively than routine motor conduction studies. (3) In this study, we found that medial epicondyle to 2 cm above the medial epicondyle is the most vulnerable place that the ulnar nerve compressed. (4) The patients had a better prognosis who were abnormal in motor nerve conduction time only, but not amplitude in compressed lesions than those who were abnormal both in velocity and amplitude. Our study suggests that SSNCSs is a practical method in detecting ulnar nerve compressed neuropathy, and sensitive in diagnosing CubTS. The compound muscle action potentials by SSNCSs may predict prognosis of CubTS.

New treatment alternatives in the ulnar neuropathy at the elbow: ultrasound and low-level laser therapy

Ulnar nerve entrapment at the elbow (UNE) is the second most common entrapment neuropathy of the arm. Conservative treatment is the treatment of choice in mild to moderate cases. Elbow splints and avoiding flexion of the involved elbow constitute majority of the conservative treatment; indeed, there is no other non-invasive treatment modality. The aim of this study was to investigate the efficacy of ultrasound (US) and low-level laser therapy (LLLT) in the treatment of UNE to provide an alternative conservative treatment method. A randomized single-blind study was carried out in 32 patients diagnosed with UNE. Short-segment conduction study (SSCS) was performed for the localization of the entrapment site. Patients were randomized into US treatment (frequency of 1 MHz, intensity of 1.5 W/cm(2), continuous mode) and LLLT (0.8 J/cm(2) with 905 nm wavelength), both applied five times a week for 2 weeks. Assessments were performed at baseline, at the end of the treatment, and at the first and third months by visual analog scale, hand grip strength, semmes weinstein monofilament test, latency change at SSCS, and patient satisfaction scale. Both treatment groups had significant improvements on clinical and electrophysiological parameters (p < 0.05) at first month with no statistically significant difference between them. Improvements in all parameters were sustained at the third month for the US group, while only changes in grip strength and latency were significant for the LLLT group at third month. The present study demonstrated that both US and LLLT provided improvements in clinical and electrophysiological parameters and have a satisfying short-term effectiveness in the treatment of UNE.

Precise localization of ulnar neuropathy at the elbow

OBJECTIVE

To report the utility of short-segment nerve conduction studies (SSNCSs) and ultrasonography (US) in the precise localization of ulnar neuropathy at the elbow (UNE) and differentiation between lesions in the retroepicondylar (RTC) groove and under the humeroulnar aponeurotic arcade (HUA; i.e., cubital tunnel).

METHODS

In a group of prospectively recruited patients with suspected UNE, four blinded examiners took a history and performed neurologic, electrodiagnostic (EDx) and ultrasonographic (US) examinations. Precise UNE localization was determined by SSNCSs criteria (conduction slowing and conduction block), and by US criteria (changes in cross-sectional area - CSA). Localizations obtained by EDx and US studies were compared.

RESULTS

We included 83 patients (86 arms) with SSNCSs or US diagnosis of UNE. US confirmed the SSNCSs localization in 45%, provided localization alone in 24%, and was unable to confirm SSNCSs localization in 23% of arms. Lesions in RTC (76%) were mainly demyelinating (63%), and localized at the medial epicondyle (29%) or 2 cm proximal to it (69%). By contrast, lesions at HUA (17%) were mainly axonal (73%), and localized 2 cm (57%) or 3 cm (43%) distal to the medial epicondyle.

CONCLUSION

SSNCSs and US are able to precisely localize UNE in the majority (93%) of arms with pathologic SSNCSs or US. UNE in RTC are predominantly demyelinating, and approx. 5-times more common than UNE at HUA that are more commonly axonal.

SIGNIFICANCE

SSNCSs and US are of similar utility and complement each other in precise UNE localization.

Ulnar neuropathy at the elbow: Five new things

Ulnar neuropathy at the elbow (UNE) is the second most frequent compression neuropathy. While other diagnostic imaging tools are emerging to assist in the diagnosis of UNE, electrodiagnosis remains the gold standard. However, the electrodiagnostic approach to UNE presents unique challenges limiting its diagnostic accuracy. We review advances in 5 areas relevant to the diagnosis of UNE: technologic advancements with modern EMG machines have allowed for reconsideration of the question of experimental error and lesion detection; how temperature effects can lead to misdiagnosis; the effect of body mass index on the electrodiagnosis of UNE; the validation of short segment studies; and the emerging role of high-resolution sonography as a diagnostic tool.

[Common and not so common nerve entrapment syndromes: diagnostics, clinical aspects and therapy]

Altogether, nerve entrapment syndromes have a very high incidence. Neurological deficits attributable to a focal peripheral nerve lesion lead to the clinical diagnosis. Frequently, pain is the dominant symptom but is often not confined to the nerve supply area. Electroneurography, electromyography, and more recently also neurosonography are the most important diagnostic tools. In most patients surgical therapy is necessary, which should be carried out in a timely manner. The entrapment syndromes discussed are suprascapular nerve entrapment, carpal tunnel syndrome, cubital tunnel syndrome, meralgia paraesthetica, thoracic outlet syndrome and anterior interosseous nerve syndrome.

The Electrodiagnosis of Ulnar Nerve Entrapment at the Elbow

Entrapment of the ulnar nerve at the elbow is the second most common focal peripheral neuropathy. Recent advances have facilitated the electrodiagnosis of this common nerve entrapment. The goals of electrodiagnosis are to localize ulnar nerve dysfunction, confirm that the disturbance is confined to the ulnar nerve, and assess the severity of ulnar nerve dysfunction. The goal of this review is to highlight the important advances in anatomy, neurophysiology and methodology that impact upon the electrodiagnosis of entrapment of the ulnar nerve at the elbow, illustrate the limits of electrodiagnosis, and discuss methodological issues that may be the subject of further study. Careful attention to elbow position, temperature, and conservative estimates of conduction block should be part of common practice. Awareness of anatomical variations in structural anatomy, anomalous innervation and fascicular arrangement of ulnar nerve fibers are required to interpret electrodiagnostic studies accurately. The most reliable finding is slowing of the ulnar across-elbow motor nerve conduction velocity to less than 50 m/sec while recording from the abductor digiti minimi muscle, and should be carefully interpreted in the presence of a polyneuropathy or other neurogenic process. Alternative techniques such as relative ulnar slowing in different ulnar nerve segments, use of alternative muscles, sensory and mixed nerve techniques provide complementary information, and like all nerve conduction studies are highly operator-dependent and should be used on a case by case basis. Recent studies have focused the electromyographer's attention on the use of shorter across-elbow segments (2-5 cm). This may offer a reasonable trade-off between sensitivity and measurement error and may result in improved electrodiagnosis.

Ulnar nerve at the elbow - normative nerve conduction study

Introduction

A goal of our work was to perform nerve conduction studies (NCSs) of the ulnar nerve focused on the nerve conduction across the elbow on a sufficiently large cohort of healthy subjects in order to generate reliable reference data.

Methods

We examined the ulnar nerve in a position with the elbow flexion of 90^o from horizontal. Motor response was recorded from the abductor digiti minimi muscle (ADM) and the first dorsal interosseous muscle (FDI).

Results

In our sample of 227 healthy volunteers we have examined 380 upper arms with the following results: amplitude (Amp)-CMAP(wrist) for ADM 9.6 ± 2.3 mV, MNCV at the forearm 60.4 ± 5.2 m/s, MNCV across the elbow 57.1 ± 5.9 m/s.

Discussion

Our study showed that motor NCSs of the ulnar nerve above elbow (AE) and below elbow (BE) in a sufficiently large cohort using methodology recommended by AANEM gave results well comparable for registration from FDI and ADM.

Compression and entrapment neuropathies

Peripheral nerve entrapments are frequent. They usually appear in anatomical tunnels such as the carpal tunnel. Nerve compressions may be due to external pressure such as the fibular nerve at the fibular head. Malignant or benign tumors may also damage the nerve. For each nerve from the upper and lower limbs, detailed clinical, electrophysiological, imaging, and therapeutic aspects are described. In the upper limbs, carpal tunnel syndrome and ulnar neuropathy at the elbow are the most frequent manifestations; the radial nerve is less frequently involved. Other nerves may occasionally be damaged and these are described also. In the lower limbs, the fibular nerve is most frequently involved, usually at the fibular head by external compression. Other nerves may also be involved and are therefore described. The clinical and electrophysiological examination are very important for the diagnosis, but imaging is also of great use. Treatments available for each nerve disease are discussed.

The impact of extended electrodiagnostic studies in ulnar neuropathy at the elbow

BACKGROUND

This study aimed to explore the value of extended motor nerve conduction studies in patients with ulnar nerve entrapment at the elbow (UNE) in order to find the most sensitive and least time-consuming method. We wanted to evaluate the utility of examining both the sensory branch from the fifth finger and the dorsal branch of the ulnar nerve. Further we intended to study the clinical symptoms and findings, and a possible correlation between the neurophysiological findings and pain.

METHODS

The study was prospective, and 127 UNE patients who were selected consecutively from the list of patients, had a clinical and electrodiagnostic examination. Data from the most symptomatic arm were analysed and compared to the department's reference limits. Student's t - test, chi-square tests and multiple regression models were used. Two-side p-values < 0.05 were considered as significant.

RESULTS

Ulnar paresthesias (96%) were more common than pain (60%). Reduced ulnar sensitivity (86%) and muscle strength (48%) were the most common clinical findings. Adding a third stimulation site in the elbow mid-sulcus for motor conduction velocity (MCV) to abductor digiti minimi (ADM) increased the electrodiagnostic sensitivity from 80% to 96%. Additional recording of ulnar MCV to the first dorsal interosseus muscle (FDI) increased the sensitivity from 96% to 98%. The ulnar fifth finger and dorsal branch sensory studies were abnormal in 39% and 30% of patients, respectively. Abnormal electromyography in FDI was found in 49% of the patients. Patients with and without pain had generally similar conduction velocity parameter means.

CONCLUSION

We recommend three stimulation sites at the elbow for MCV to ADM. Recording from FDI is not routinely indicated. Sensory studies and electromyography do not contribute much to the sensitivity of the electrodiagnostic evaluation, but they are useful to document axonal degeneration. Most conduction parameters are unrelated to the presence of pain.

The Electrodiagnosis of Neuropathy: Basic Principles and Common Pitfalls

Electrodiagnostic studies are a critical tool for the identification and study of peripheral neuropathy, enabling definition of the pathophysiologic type of nerve injury, its distribution, severity, and the degree of motor or sensory nerve involvement. These data help to differentiate the varieties of neuropathy from other neuromuscular diseases. Nerve conduction studies and electromyography, although widely performed, are complex techniques and are subject to a wide range of artifacts, which can result in missed or erroneous diagnoses. Without proper education, training, and experience in neuromuscular disease and the techniques of electrodiagnosis and careful attention to potential sources of error, the critical information needed to properly diagnose and treat patients with neuropathy is unreliable and may lead to wasted resources and patient injury.

Ultrasonographic measurements in cubital tunnel syndrome

The cubital tunnel is the most common site of ulnar nerve entrapment. Previous ultrasound studies have demonstrated enlargement of the ulnar nerve in cubital tunnel syndrome but did not report on the cubital tunnel itself. Twenty-two individuals with cubital tunnel syndrome were evaluated with nerve conduction studies and ultrasound. The ultrasound measurement that most strongly correlated with conduction velocity was the ratio of ulnar nerve to cubital tunnel cross-sectional area with the elbow flexed. Measurement of this ratio may improve the diagnostic accuracy of ultrasound in cubital tunnel syndrome, although further investigation is needed.

Mixed Latency Difference for Diagnosis of Ulnar Neuropathy at the Elbow

OBJECTIVE

To provide reference values and to compare this technique with the standard motor conduction velocity (MCV) of the ulnar nerve.

DESIGN

Retrospective unmasked study.

SETTING

Private and institutional practice.

PARTICIPANTS

The reference group included 57 healthy volunteers. Patients included 100 subjects with suspected ulnar neuropathy at the elbow (UNE) referred for neurophysiologic evaluation. This group was subdivided into 2 groups: group A was composed of 45 patients with UNE confirmed by MCV of the ulnar nerve, and group B included 55 patients with suspected UNE in whom the diagnosis could not be established by MCV of the ulnar nerve.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Differences between peak latencies of ulnar and median mixed nerve action potentials at the arm, after stimulating these nerves at the wrist. This was called mixed latency difference.

RESULTS

The upper normative limit of the mixed latency difference was 1.1 ms, and there was a significant correlation with height. In group A, the mixed latency difference was abnormal in 80% of the cases and could not be calculated in 18%. In group B, the mixed latency difference was abnormal in 8 (15%) patients. All of these had abnormal "inching" of the ulnar nerve across the elbow.

CONCLUSIONS

The mixed latency difference was particularly useful in cases of mild UNE.

Distance measure error induced by displacement of the ulnar nerve when the elbow is flexed

OBJECTIVES

To determine the presence of ulnar nerve displacement at the elbow when it is flexed and to determine its effect on distance measurements using the conventional measurement method for nerve conduction studies (NCSs).

DESIGN

Comparing the ultrasonography-assisted distance measurement method with the conventional measurement method.

SETTING

An electrodiagnostic laboratory at a university hospital.

PARTICIPANTS

Seventy-eight elbows of 39 healthy volunteers.

INTERVENTIONS

We used high-resolution ultrasonography in real time. Based on sonographic searching, we marked 3 points on the skin through the course of the displaced ulnar nerve when the elbow is flexed: (1) point A, 7 cm above the elbow (from the midpoint between the medial epicondyle tip and olecranon in the postcondylar groove [point M]); (2) point B, 3 cm below the elbow; and (3) point C, the point closest to the medial epicondyle tip.

MAIN OUTCOME MEASURES

Distance measurements between points A, B, and C were taken. These values were compared with measurements obtained through conventional measurement methods.

RESULTS

Ulnar nerve displacement occurred in 24.3% (19/78) of the elbows; approximately 20.5% (16/78) were subluxation, and 3.8% (3/78) were dislocation. In the ulnar nerve displacement group, the distance between points A and C was 5.84+/-0.33 cm (range, 5.10-6.30 cm), and the distance between points B and C in the flexed position was 3.35+/-0.19 cm (range, 3.10-3.70 cm). When the conventional distance measurement was used, the ulnar nerve conduction velocity across the elbow was overestimated by approximately 5.33+/-2.29 m/s in the ulnar nerve displacement group.

CONCLUSIONS

This distance measurement error may be responsible for the decreased sensitivity found in NCSs that test for ulnar neuropathy at the elbow. If the NCS results are normal in patients who have clear symptoms of ulnar neuropathy, the possibility of ulnar nerve displacement at the elbow should be considered, and further investigation with ultrasonography would be beneficial.

Short-segment nerve conduction studies in the localization of ulnar neuropathy of the elbow: Use of flexor carpi ulnaris recordings

Short-segment nerve conduction studies were performed in 17 limbs with clinical features suggestive of ulnar neuropathy at the elbow. Recording from flexor carpi ulnaris yielded 93% sensitivity, compared with 71.4% when recording from abductor digiti minimi. The rationale underlying the technique is discussed. This approach should be of value as a diagnostic adjunct in technically challenging cases of ulnar neuropathy at the elbow.

Short-segment nerve conduction studies in ulnar neuropathy at the elbow

The aim of the study was to assess the diagnostic value of short-segment nerve conduction studies (NCS) at 2-cm intervals from 4 cm above to 4 cm below the medial epicondyle in a large group of patients with ulnar neuropathy at the elbow (UNE). Furthermore, we wanted to compare electrodiagnostic and clinical findings. We evaluated 73 arms in 70 patients with UNE and observed the following abnormalities on short-segment NCS: focal conduction block (CB) in 1, focal CB with increased latency change in 34, and increased latency change alone in 25. Short-segment NCS had an additional localizing value in 28 arms of the 37 patients (76%) with motor conduction velocity (MCV) slowing across the elbow only or with nonlocalizing electrodiagnostic findings. The lesion was located above the elbow in 32 arms (53%), at the epicondyle in 16 arms (27%), and below the epicondyle in 12 (20%) of the 60 arms with focal CB or increased latency change on short-segment NCS. Patients with CB on routine and short-segment NCS had muscle weakness significantly more often than patients without CB. Thus, short-segment NCS are useful in localizing the lesion in patients with UNE and CB on routine NCS and have additional diagnostic value in patients with MCV slowing across the elbow or with nonlocalizing signs on routine nerve conduction studies. We recommend its use in all patients in whom UNE is suspected.