Ulnar neuropathy with abnormal non-localizing electrophysiology: Clinical, electrophysiological and ultrasound findings

doi:10.1016/j.clinph.2018.07.020

Clinical Neurophysiology

Volume 129, Issue 10, October 2018, Pages 2155-2161

https://doi.org/10.1016/j.clinph.2018.07.020 Get rights and content

Highlights

•
A quarter of ulnar neuropathies with abnormal electrophysiology were axonal non-localizing (NL-UN).
•
Most NL-UNs (87%) were in males with severe or moderate clinical and electrophysiological ratings.
•
Ultrasound had a critical role in localization and classification that facilitated management.

Abstract

Objective

To systematically study demographic, clinical, electrophysiological and nerve ultrasound characteristics of ulnar neuropathy with abnormal non-localizing electrophysiology (NL-UN) and further define the utility of ultrasound over and above the conventional electro-diagnostic approach.

Method

NL-UNs were prospectively identified from 113 consecutive referrals with suspected ulnar neuropathy. All received electro-diagnostic tests and ulnar nerve ultrasound. NL-UN severity was graded using clinical and electrophysiological scales.

Results

In 64 of 113 referrals, an ulnar mono- neuropathy was confirmed by electrophysiology. Sixteen of these 64 (25%) had NL-UN, predominantly males (14 out of 16 patients) with severe or moderate clinical and electrophysiological ratings. Ultrasound showed focal ulnar neuropathy at the elbow in 13 out of 16, and diffuse ulnar nerve abnormality in three, and identified a likely or possible causative mechanism in 11.

Conclusion

A significant proportion (a quarter) of ulnar neuropathies with abnormal electrophysiology were NL-UN, of heterogeneous etiology; the majority were males with significant disability and axonal loss. Ultrasound had a significant role in localization and classification that facilitated management.

Significance

To our knowledge, this is the first systematic prospective study that analyzes the demographic, clinical, electrophysiological and ultrasound characteristics of NL-UN in a routine clinical neurophysiology setting.

Introduction

Ulnar neuropathy, the second most common mono-neuropathy, is usually due to focal nerve pathology at the elbow, with an estimated incidence of 24.7/10⁵/year (Mondelli et al., 2005). It typically presents with paraesthesia or sensory loss in the little and ring fingers and weakness of ulnar innervated muscles. Diagnosis is usually based on clinical findings and abnormal electrophysiology. Electrodiagnostic tests can localize the lesion by demonstrating focal conduction slowing, with or without temporal dispersion and conduction block across the elbow (AAEM, 1999a), with a sensitivity varying from 38 to 89% (AAEM,1999b). In some ulnar neuropathies however, electrophysiology is abnormal, showing findings of axonal degeneration, but non-localizing (Jabre and Wilbourn, 1979, Schady et al., 1998, Wilbourn, 1987). From now on we will refer to these subgroup of ulnar neuropathies as ‘Non Localising Ulnar Neuropathy (NL-UN). NL-UN is often mentioned in the literature, but a systematic analysis of its incidence, demographic, severity and distinctive pathophysiology is not available. NL-UN may be associated with important impairment and disability, but management can be difficult in the absence of anatomically defining studies. It is unclear if NL-UN is indeed non-localized, or if it may be an undetected focal ulnar neuropathy that might benefit from decompression. This could be particularly difficult in patients with diabetes or other systemic disorder, in whom the ulnar mono-neuropathy could have a metabolic or ischemic basis, rather than being secondary to focal nerve injury.

In recent years, high-resolution nerve ultrasound has emerged as a reliable and sensitive technique to complement electrophysiological investigation of mono-neuropathies, and previous papers have also included data on utility of nerve ultrasound in electrodiagnostically non-localizable ulnar neuropathy at the elbow (Beekman et al., 2004a, Beekman et al., 2004b, Beekman et al., 2011, Omejec and Podnar, 2015).

The purpose of this study was to investigate frequency, demographic, clinical and electrophysiological characteristics of NL-UN and use ultrasound in order to assist with classification and to examine the utility of ultrasound over and above the conventional electro-diagnostic approach.

Section snippets

Patients

In this prospective study, NL-UN was identified from all consecutive referrals with suspected ulnar neuropathy to our neurophysiology clinic, from May 2014 to January 2016.

The procedures followed were in accordance with the Helsinki Declaration of 1975 and were all part of the routine procedures for investigation of ulnar neuropathy at our Institution.

Clinical inclusion criteria were: numbness and/or paresthesia in the little and ring fingers with or without weakness and atrophy of

Results

One hundred and thirteen patients (52 females) with suspected ulnar neuropathy were referred. Electrodiagnostic tests confirmed an ulnar neuropathy in 64 (64/113 = 57%). Sixteen of these 64 (25%) had NL-UN. In the remaining 48 neuropathies (75%), electrophysiology localized the ulnar nerve lesion at the elbow (UNE) (Table 1).

Table 2 shows demographic, clinical and electrophysiological severity, and ultrasound findings in individual patients with NL-UN. Details of the sensory and motor

Discussion

Ulnar neuropathy with abnormal non-localizing electrophysiology is often associated with significant disability and is difficult to manage, especially without systematic studies to guide the physicians.

To our knowledge, this is the first systematic analysis of frequency, demographic, clinical, electrophysiological and ultrasound findings of NL-UN.

We found that NL-UN is not uncommon, forming a quarter of the ulnar neuropathies confirmed by electrodiagnostic tests in our cohort.

There was a

Conclusions

NL-UNs were a significant proportion (a quarter) of ulnar neuropathies with abnormal electrophysiology. The majority were in males with significant clinical disability and axonal loss on electrophysiology. Ultrasound had a significant role in localization and classification of NL-UN that facilitated management.

Conflict of interest

None of the authors has potential conflicts of interest to be disclosed.

Acknowledgements

The authors wish to thank Professor LD Blumhardt for critical review of the manuscript and ‘SonoSite FujiFilm’ for providing the SonoSite Edge System used for all nerve ultrasound recordings.

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View full text

Ulnar neuropathy with abnormal non-localizing electrophysiology: Clinical, electrophysiological and ultrasound findings

Highlights

Abstract

Objective

Method

Results

Conclusion

Significance

Introduction

Section snippets

Patients

Results

Discussion

Conclusions

Conflict of interest

Acknowledgements

J Neurol Sci

Neurophysiol Clin

J Hand Surg Edinb

Clin Neurophysiol

Clin Neurophysiol

Clin Neurophysiol

J Diab Comp

Clin Neurophysiol

Practice parameter for electrodiagnostic studies in ulnar neuropathy at the elbow: summary statement

Arch Phys Med Rehabil

The electrodiagnostic evaluation of patients with ulnar neuropathy at the elbow: literature review of the usefulness of nerve conduction studies and needle electromyography

Muscle Nerve

Surgical management of ulnar nerve compression at the elbow: an analysis of the literature

J Neurosurg

Ultrasonography in patients with ulnar neuropathy at the elbow: comparison of cross-sectional area and swelling ratio with electrophysiological severity

Muscle Nerve