Mixed Latency Difference for Diagnosis of Ulnar Neuropathy at the Elbow

A Three months Electrodiagnostic Follow-Up of Patients Suspected of having Ulnar Nerve Involvement at Elbow Level with Normal Conventional Electrodiagnostic Study at First Evaluation

BACKGROUND

Compression of ulnar nerve at the elbow is the second most common peripheral neuropathy of the upper extremity.

OBJECTIVE

Due to the lack of the gold diagnostic standard for ulnar nerve involvement at elbow level (UNE) and the lack of sufficient study in this field, we decided to evaluate patients with symptoms of this disease who have normal conventional electrodiagnostic study (EDX) in first evaluation.

MATERIALS AND METHODS

In this cross-sectional study, 18 persons were selected from patients who were referred to the clinic of Physical Medicine and Rehabilitation. If conventional EDX was normal, compound nerve action potential (CNAP) test (peak latency and amplitude) was carried out. Patients with normal conventional EDX but abnormal ulnar CNAP included to our study. After 3 months, if they had not been treated for ulnar neuropathy, they were reexamined by conventional EDX plus ulnar CNAP measurement.

RESULTS

In total, 18 patients (11 females, 7 males) aged 28-58 years old (mean = 40.11) were analyzed in this study. After 3 months, 14 patients (77.8%) demonstrated parameter changes consistent with UNE in conventional EDX.

CONCLUSION

Based on the results of this study, ulnar CNAP has diagnostic value in patients with symptoms of UNE who have normal routine EDX. Therefore, ulnar CNAP should be taken into account for early diagnosis of ulnar neuropathy when routine electrodiagnostic tests are normal.

An Additional Electrodiagnostic Tool for Ulnar Neuropathy: Mixed across the Elbow

Background  Diagnosing ulnar neuropathy at the elbow (UNE) remains challenging despite guidelines from national organizations. Motor testing of hand intrinsic muscles remains a common diagnostic method fraught with challenges.

Objective  The aim of the study is to demonstrate utility of an uncommon nerve conduction study (NCS), mixed across the elbow, when diagnosing UNE.

Methods  Retrospective analysis of 135 patients, referred to an outpatient University-based electrodiagnostic laboratory with suspected UNE between January 2013 and June 2019 who had motor to abductor digiti minimi (ADM), motor to first dorsal interosseus (FDI), and mixed across the elbow NCS completed. To perform the mixed across the elbow NCS, the active bar electrode was placed 10-cm proximal to the medial epicondyle between the biceps and triceps muscle bellies. The median nerve was stimulated at the wrist followed by stimulation of the ulnar nerve at the ulnar styloid. The difference between peak latencies, labeled the ulnar-median mixed latency difference (U-MLD), was used to evaluate for correlation between the nerve conduction velocities (NCV) of ADM and FDI.

Results  Pearson r -values = −0.479 and −0.543 ( p  < 0.00001) when comparing U-MLD to ADM and FDI NCV across the elbow, respectively. The negative r -value describes the inverse relationship between ulnar velocity across the elbow and increasing U-MLD.

Conclusion  Mixed across the elbow has moderate–strong correlation with ADM and FDI NCV across the elbow. All three tests measure ulnar nerve function slightly differently. Without further prospective data, the most accurate test remains unclear. The authors propose some combination of the three tests may be most beneficial when diagnosing UNE.

Ulnar neuropathy at the elbow: Reappraisal of the wrist-upper arm latency difference between ulnar and median nerves

OBJECTIVES

To evaluate the sensitivity and specificity of the latency difference (DLat) between ulnar and median nerves of the arm after stimulation at the wrist; one of the easiest techniques proposed for recognizing ulnar neuropathy at the elbow (UNE). As latency difference is not a standardized technique, we set up a multicenter study to recruit large numbers of normal subjects and patients with UNE or generalized neuropathy.

METHODS

Six centers participated in the study with data obtained from three groups of participants, controls (CTRLs), patients with UNE and patients with generalized neuropathy (GNP). We first verified the anatomical superposition of the ulnar and median nerves in cadaver examination. The optimal recording site for these two nerves was found to be 10 cm above the medial epicondyle. We then standardized the position of the arm with full extension of the elbow and stimulated first the median and then the ulnar nerves at the wrist. CTRLs were examined on both arms at two consecutive visits.

RESULTS

We recorded 32 idiopathic UNE cases, 44 GNP patients and 62 controls. We demonstrated that a DLat cut-off value of 0.69 ms brings a sensitivity of 0.86 and specificity of 0.89 to discriminate CTRLs from UNE. We also validated that intra-examiner reproducibility was good.

CONCLUSION

We report a lower normal value for DLat than reported in several non-standardized studies and CTRL and UNE groups have clearly separated DLat values.

SIGNIFICANCE

Due to its high sensitivity, our standardized technique could be used as a first-line diagnostic tool when UNE is suspected.

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.

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.