The Electrodiagnosis of Ulnar Nerve Entrapment at the Elbow

Round table discussion: the management of idiopathic cubital tunnel syndrome

Idiopathic cubital tunnel syndrome is the second most common neuropathy in the upper limb. Best evidence regarding the surgical management of this condition has evolved from anterior or submuscular transposition as the former reference standard, to in situ simple release. Differences of opinion remain regarding the timing of surgery, type of surgery and adjunctive surgery. Four surgeons with Level 5 expertise were asked to answer specific questions regarding this condition.

The Unpredictable Ulnar Nerve-Ulnar Nerve Entrapment from Anatomical, Pathophysiological, and Biopsychosocial Aspects

Peripheral nerves consist of delicate structures, including a rich microvascular system, that protect and nourish axons and associated Schwann cells. Nerves are sensitive to internal and external trauma, such as compression and stretching. Ulnar nerve entrapment, the second most prevalent nerve entrapment disorder after carpal tunnel syndrome, appears frequently at the elbow. Although often idiopathic, known risk factors, including obesity, smoking, diabetes, and vibration exposure, occur. It exists in all adult ages (mean age 40-50 years), but seldom affects individuals in their adolescence or younger. The patient population is heterogeneous with great co-morbidity, including other nerve entrapment disorders. Typical early symptoms are paresthesia and numbness in the ulnar fingers, followed by decreased sensory function and muscle weakness. Pre- and postoperative neuropathic pain is relatively common, independent of other symptom severity, with a risk for serious consequences. A multimodal treatment strategy is necessary. Mild to moderate symptoms are usually treated conservatively, while surgery is an option when conservative treatment fails or in severe cases. The decision to perform surgery might be difficult, and the outcome is unpredictable with the risk of complications. There is no consensus on the choice of surgical method, but simple decompression is relatively effective with a lower complication rate than transposition.

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.

An electrodiagnostic grading system for ulnar neuropathy at the elbow

INTRODUCTION

Ulnar neuropathy at the elbow (UNE) is the second most common entrapment neuropathy. Our goal was to create and analyze a grading system for UNE electrodiagnostic severity.

METHODS

We retrospectively analyzed EMG reports with UNE. We then classified 112 limbs as having mild, moderate, or severe grade UNE based on electrodiagnostic findings. The association between presenting symptoms and signs, EMG findings, treatment type, and electrodiagnostic grade was statistically analyzed.

RESULTS

Seventeen limbs (15.2%) had mild, 80 (71.4%) had moderate, and 15 (13.4%) had severe UNE. Symptoms (P = .016), exam findings (P < .001), and treatment type (P = .043) were significantly associated with electrodiagnostic grade.

DISCUSSION

Our UNE grading system was significantly related to symptoms, physical exam, and treatment selection and may be useful to measure electrodiagnostic severity.

Electrodiagnostic Findings in 441 Patients with Ulnar Neuropathy - a Retrospective Study

Purpose

Ulnar neuropathy (UN) is the second most common focal neuropathy in the upper extremities. Electrodiagnostic studies (EDx), including nerve conduction study (NCS) and electromyography (EMG), are reliable tools for the diagnosis of ulnar neuropathy. We aimed to retrospectively analyze the medical records of patients diagnosed with ulnar neuropathy in a seven-year period and report our findings.

Patients and methods

In this retrospective study, documents of the patients whose ulnar nerve injury was confirmed through electrodiagnostic study in two departments of Physical Medicine and Rehabilitation were collected and demographic data, subjective complaints of the patient, the cause, and electrodiagnostic findings were extracted from each patient’s file. The following points were specifically evaluated in the electrodiagnostic records; type of injury, location, accompanying injuries, sensory nerve action potentials (SNAP) of the fifth finger, SNAP of dorsal ulnar cutaneous nerve (DUCN), compound muscle action potential (CMAP) of abductor digiti minimi (ADM) muscle, nerve conduction velocity (NCV) across elbow, patterns of muscle involvement, and the severity of insult.

Results

Out of 441 records, 305 (69.2%) were male and 68.1% were non-traumatic. Based on our clinical criteria, the intensity of the injury was mild in most cases. The elbow and forearm were the most involved regions in non-traumatic and traumatic cases respectively. Across elbow nerve conduction velocity showed decreased velocity in 71% of records. In non-traumatic cases, the most affected muscle was ADM (97%) and then FDI (85%).

Conclusion

In focal entrapments such as ulnar neuropathy, electrodiagnostic findings are very helpful in assessing location, severity, and type of injury. If a consensus is achieved for the diagnosis of UN, even retrospective studies can become valuable sources for studying UN.

Ulnar Neuropathy at the Elbow Associated With Focal Demyelination in the Proximal Forearm and Intraoperative Imaging Correlation

Ulnar nerve focal demyelination (FD) in the forearm [defined as conduction block (CB) and or temporal dispersion (TD)] has been described with immune-mediated neuropathy and with compression affecting the forearm segment of the nerve. The association of FD in the forearm with entrapment ulnar neuropathy at the elbow, as well as the intraoperative imaging of the abnormal ulnar nerve at the flexor carpi ulnaris muscle level (FCU), has not been reported before. We report a 33-years-old woman presented with only sensory symptoms of the right hand suggestive of right ulnar neuropathy for the last 10 years. On clinical examination, she had reduced pinprick sensation on the little and ring fingers with no motor deficit. Nerve-conduction study showed slowing of conduction velocity across the elbow on the right when recording at the abductor digiti minimi (ADM) and first dorsal interossei (FDI). There was 63% amplitude drop when stimulating below the elbow compared to distal stimulation at the wrist. Increment inching study localized the block at 5 cm distal to the medial epicondyle. During surgical transposition, the ulnar nerve was swollen, and edematous in the segment where the nerve enters the FCU muscle, which provides a physiological explanation for the electrophysiological findings. After the surgery, the patient reported complete resolution of the symptoms. This case demonstrate that ulnar nerve motor potential FD at the proximal forearm could be recorded and it is still compatible with ulnar-nerve entrapment at the elbow.

Etiology, Diagnosis, and Treatment of Dynamic Nerve Compression Syndromes of the Elbow Among High-Level Pitchers: A Review of 7 Cases

Background:

Dynamic compressive neuropathies around the elbow are a rare entity described by a relatively small body of literature, mostly consisting of single-case reports. No standardized diagnostic protocols have been described to date. To the authors’ knowledge, this study represents the largest case series of dynamic compressive neuropathies in the upper extremity.

Purpose:

To identify various etiologies of dynamic compressive neuropathies around the elbow, devise a systematic diagnostic protocol, and review treatment options.

Study Design:

Case series; Level of evidence, 4.

Methods:

A retrospective review was conducted of patients who presented to a single practice between 2013 and 2017 and were diagnosed with a dynamic compressive neuropathy around the elbow.

Results:

A total of 7 patients were identified, with a mean follow-up of 2 years. All patients were high-level pitchers. One patient was a minor league pitcher; 4 patients were National Collegiate Athletic Association athletes; and 2 patients were high school athletes. All patients underwent a systematic diagnostic workup. The diagnosis was established with dynamic nerve conduction testing. Three etiologies for dynamic nerve compression around the elbow were identified: 1 case of lateral antebrachial cutaneous nerve compression by the biceps tendon, 3 cases of ulnar nerve compression by an anconeus epitrochlearis muscle, and 3 cases of posterior interosseous nerve compression at the arcade of Frohse with hypertrophic extensor carpi radialis brevis and extensor digitorum communis muscles. Two patients were treated conservatively, while 5 patients required surgery. All patients were able to return to pitching.

Conclusion:

Dynamic compressive neuropathies around the elbow are rare entities that present unique diagnostic challenges to the treating clinician. In this cohort, all patients were young throwing athletes. Physical examination of the patient frequently lacks typical findings of chronic nerve entrapment syndromes. Dynamic nerve conduction studies establish the diagnosis, and treatment often requires surgical decompression to achieve complete resolution of symptoms.

Normative Ulnar Nerve Conduction Study: Comparison of Two Measurement Methods

Background:

Given the high prevalence rate of ulnar neuropathy and importance of its proper management, to have a baseline information about the normative value of motor nerve conduction of first dorsal interosseous (FDI) muscle and abductor digiti minimi muscle (ADM) and their differences as well as their relation with different demographic characteristics of our population, we aimed to determine and compare the mean value of motor conduction velocity of FDI and ADM at forearm and across the elbow among the normal population.

Materials and Methods:

In this cross-sectional study, healthy participants were enrolled in the study. Ulnar nerve motor nerve conduction velocity (MNCV) was recorded from the ADM and the FDI at forearm and across the elbow. Mean MNCV of the ulnar nerve recorded from ADM and FDI was compared. In addition, MNCV of the ulnar nerve measured at the forearm and across the elbow was compared also.

Results:

During this study, 165 healthy volunteers selected and participated in the study. Mean of ulnar nerve MNCV for ADM was significantly lower than FDI, both at forearm and across the elbow (P < 0.001). Mean of ulnar nerve MNCV was significantly lower at forearm comparing than elbow level for both ADM and FDI (P < 0.001).

Conclusion:

The findings of the current study provide us a baseline data regarding the normative mean value of ulnar nerve MNCV in different locations, which could be used for providing an appropriate diagnostic protocol for ulnar nerve neuropathy. However, further studies among patients suspected with ulnar nerve neuropathy are needed.

Cubital Tunnel Syndrome: Incidence and Demographics in a National Administrative Database

Background

Compressive neuropathy of the ulnar nerve at the elbow, or cubital tunnel syndrome (CuTS), is the second most common entrapment neuropathy of the upper extremity after carpal tunnel syndrome. While several studies have reported risk factors and outcomes for select populations (mostly surgical), it is difficult to interpret these data without an accurate measure of CuTS disease burden in the general population.

Objective

To estimate the incidence of CuTS among US health plan enrollees, using a large administrative health care claims database comprised of individuals from all 50 states.

Methods

An administrative database of commercial insurance beneficiaries was queried for diagnosis and treatment of CuTS over a 6-yr period. We examined subsequent claims to determine frequency of subsequent surgical treatment. Descriptive statistics were used to determine the association of incident cases and surgical treatment with age and gender.

Results

The estimated adjusted incidence rate of CuTS is 30.0 per 100 000 person-years. Of the 53 401 identified new cases within this cohort from 2006 to 2012, 41.3% were treated surgically. Incident cases were identified more frequently in men than in women (31.2 vs 28.8 cases per 100 000 person-years), though we observed more cases in women than in men below 50 yr of age (20.9 vs 19.5 cases per 100 000 person-years). Overall, incident cases increase with age in both men and women. In addition to incident cases being more common with increasing age, the percentage of cases treated surgically also increases with age (surgery in 34.4% of cases in the 18-30 yr group vs 48.8% of cases in the 60-65 yr group).

Conclusion

The purpose of this study was to estimate the incidence of CuTS among US health plan enrollees. This is the largest published study on the incidence of CuTS, and the first to look at a US population. The overall adjusted incidence of CuTS was 30.0 per 100 000 person-years. Of patients who developed CuTS, 41.3% were treated surgically during the study period. Our results corroborate previously reported literature suggesting incidence increases significantly with age, with a slightly higher incidence in males. A high percentage of people who were diagnosed with CuTS and ended up receiving surgical intervention (41.3%) were older males. These results may aid practitioners in providing some basic prognostic information to patients who develop CuTS.

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.

Diagnosing ulnar neuropathy at the elbow using magnetic resonance neurography

INTRODUCTION

Early diagnosis of ulnar neuropathy at the elbow is important. Magnetic resonance neurography (MRN) images peripheral nerves. We evaluated the usefulness of elbow MRN in diagnosing ulnar neuropathy at the elbow.

METHODS

The MR neurograms of 21 patients with ulnar neuropathy were reviewed retrospectively. MRN was performed prospectively on 10 normal volunteers. The MR neurograms included axial T1 and axial T2 fat-saturated and/or axial STIR sequences. The sensitivity and specificity of MRN in detecting ulnar neuropathy were determined.

RESULTS

The mean ulnar nerve size in the symptomatic and normal groups was 0.12 and 0.06 cm(2) (P < 0.001). The mean relative signal intensity in the symptomatic and normal groups was 2.7 and 1.4 (P < 0.01). When using a size of 0.08 cm(2), sensitivity was 95% and specificity was 80%.

DISCUSSION

Ulnar nerve size and signal intensity were greater in patients with ulnar neuropathy. MRN is a useful test in evaluating ulnar neuropathy at the elbow.

Ulnar neuropathy with normal electrodiagnosis and abnormal nerve ultrasound

Ulnar neuropathy at the elbow (UNE) is the second most common entrapment neuropathy. It is diagnosed with electrodiagnostic studies, but they can yield false-negative results. Ultrasound was used to examine 4 patients with UNE and negative electrodiagnostic findings, and it showed ulnar nerve enlargement near the elbow in all cases, with a mean cross-sectional area of 20.1 mm. This indicates that ultrasound may be a useful tool for assessing those with UNE symptoms and normal electrodiagnostic findings.

Natural history and conservative management of cubital tunnel syndrome

Successful treatment of cubital tunnel syndrome requires obtaining a history of the physical and environmental factors involved for each patient, conducting a thorough physical examination, and staging and implementing an individually tailored treatment plan. Rest and avoiding pressure on the nerve by activity modification might be sufficient. If symptoms persist, splint immobilization of the elbow is warranted. Keep in mind that the natural history of untreated cubital tunnel syndrome includes spontaneous improvement in approximately half of patients.

Evoked cavernous activity: measuring penile autonomic innervation following pelvic surgery

To assess cavernous nerve integrity, we measured evoked cavernous activity (ECA) in 16 men who underwent nerve sparing radical prostatectomy (NS group) and 11 men who underwent non-nerve-sparing surgery (non-NS group). The right median nerve was electrically stimulated and ECA was recorded with two concentric electromyography needles placed into the right and left cavernous bodies. We simultaneously recorded hand and foot sympathetic skin responses (SSRs) as controls. All subjects had recordable SSR, and all subjects following nerve-sparing radical prostatectomy had reproducible ECA. Of the 11 non-NS subjects, eight had no response, indicating interrupted corporal innervation. Three subjects had reproducible ECA, one of whom had a very late latency, suggesting residual innervation was present. The mean latencies of ECA were similar to foot SSR mean latencies (P>0.05), but not to hand SSR latencies. The non-NS group was significantly different from the NS group for the presence of ECA (P<0.001). ECA is a viable method of evaluating the autonomic innervation of the penis.

[Supracondylar process and supratrochlearforamen of the humerus: a case report and a review of the literature]

The authors present a case where the main variants of the humerus were associated on the same specimen: the supracondylar process and the supratrochlear foramen. The supracondylar process, a bony prominence situated on the anteromedial surface of the humerus in the vicinity of the medial epicondyle, could be at the origin of ulnar or median nerve and brachial artery compression syndromes, especially when associated with Struthers' ligament.

MATERIAL AND METHOD

The anatomic specimen was discovered accidentally during a larger study aimed at establishing a current norma anatomica and morphometry of the humerus. The supracondylar process and the supratrochlear foramen were morphologically and morphometrically analyzed.

RESULTS AND DISCUSSION

The supracondylar process was situated on the anteromedial surface of a left humerus, roughly 5 cm above the medial epicondyle. It was 12.4 mm in length, mediodistally directed. The supratrochlear foramen was situated above the lateral part of the humeral trochlea, just adjacent to the middle branch of trifurcation of the anterior border of the humerus. It was ovoid in shape with the long axis transversally (6.3/3.7 mm).

CONCLUSIONS

Presentation of such variants contributes to increasing the anatomical data capital and might be important for diagnosis of peripheral neurovascular compression syndromes.