Analysis of the position of the branches of the ulnar nerve in Guyon's canal using high-resolution MRI in positions adopted by cyclists

Ultrasound of the Ulnar Nerve: A Pictorial Review: Part 2: Pathological Ultrasound Findings

This is the second part of a two-part article in which we focus on the ultrasound (US) appearance of the pathological ulnar nerve (UN) and its main branches. Findings in a wide range of our pathological cases are presented with high-resolution US images obtained with the latest-generation US machines and transducers.

Elastography of nerves in the wrists of cyclists

Purpose

This study aimed to investigate changes in the elasticity of the median and ulnar nerves in cyclists.

Material and methods

The study included 30 cyclists and 2 non-biking reference groups that included 32 healthy volunteers and 32 individuals with ulnar nerve entrapment neuropathies. All participants underwent physical, ultrasonographic, and elastographic examinations including assessment of nerve cross-sectional area (CSA) and stiffness (SWE). The cyclists' group was tested before and after a 2-hour workout.

Results

The values of ulnar nerve CSA and stiffness in Guyon's canal in resting cyclists were 5.30 ± 1.51 mm2 and 49.05 ± 11.18 kPa, respectively. These values were significantly higher than in the healthy volunteers, but not higher than in the nerve entrapment group. Median nerve CSA and stiffness at rest were 9.10 ± 2.61 mm2 and 38.54 ± 14.87 kPa, respectively. Both values were higher than respective values in the healthy group. Cycling induced an increase in all these parameters, although the increase in nerve stiffness was more noticeable than in CSA.

Conclusions

The elasticity of the median and ulnar nerve in cyclists remains within normal limits, questioning the belief that cyclists are at risk of nerve palsy in Guyon's canal. However, cycling workout does exert compression, resulting in transient oedema of both nerves. The dynamics of changes was more noticeable in SWE examination than in conventional ultrasound, which may depend on SWE sensitivity.

The elastography of distal ulnar nerve branches in cyclists

INTRODUCTION

Forced elbow flexion and pressure during bicycling result in ulnar nerve traction and pressure exerted in Guyon's canal or the nerve's distal branches. The compression of the nerves causes a change in their stiffness related to edema and eventually gradual fibrosis.

PURPOSE

This study aimed to evaluate the elastography of terminal branches of the ulnar nerve in cyclists.

STUDY DESIGN

Cross-sectional study.

METHODS

Thirty cyclists, 32 healthy individuals, and 32 volunteers with ulnar nerve entrapment neuropathies participated in the study. Each participant underwent a nerve examination of the cubital tunnel, Guyon's canal and the deep and superficial branches of the ulnar nerve using shear wave elastography. The cyclist group was tested before and after a 2-hour-long workout.

RESULTS

Before cycling workouts, the ulnar nerve stiffness in the cubital tunnel and Guyon's canal remained below pathological estimates. Cycling workouts altered nerve stiffness in the cubital tunnel only. Notably, the stiffness of the ulnar terminal branches in cyclists was increased even before training. The mean deep branch stiffness was 50.85 ± 7.60 kPa versus 20.43 ± 5.95 kPa (p < 0.001) in the cyclist and healthy groups, respectively, and the mean superficial branch stiffness was 44 ± 12.45 kPa versus 24.55 ± 8.05 kPa (p < 0.001), respectively. Cycling contributed to a further shift in all observed values.

DISCUSSION

These observations indicate the existence of persistent anatomical changes in the distal ulnar branches in resting cyclists that result in increased stiffness of these nerves. The severity of these changes remains, however, to be determined.

CONCLUSIONS

These data show elastography values of the ulnar terminal branches in healthy individuals and cyclists where despite lack of clinical symptoms that they seem to be elevated twice above the healthy range.

Preventive strategies, exercises and rehabilitation of hand neuropathy in cyclists: A systematic review

BACKGROUND

Recreation, transportation and sport are the most common uses of bicycles. Unfortunately, repetitive bicycle use can also cause injuries, such as osteoarticular direct and undirect traumatisms and sometimes compression nerve entrapment caused by an extrinsic compressive force.

PURPOSE

The aim of the study is to define diagnostic process, preventive strategies, and treatment of ulnar and median neuropathies in cyclists.

STUDY DESIGN

Systematic review.

METHODS

A search was conducted on PubMed, EMBASE, the Cochrane Library, and Web of Science. Two reviewers independently reviewed articles and came to a consensus about which ones to include. The authors excluded all duplicates, articles involving individuals with other sport-related injuries than cycling, and articles unrelated to peripheral neuropathies. Articles were included if hand palsy was due to peripheral compression of ulnar or median nerve in cyclists.

RESULTS

The search identified 15,371 articles with the keywords "Peripheral Nervous System Diseases" OR "neuropathy" OR "ulnar palsy" OR "median palsy" AND "bicycling" OR "bike" OR "bicycle" OR "cyclist". The reviewers analyzed 48 full texts. There were 20 publications that met the criteria and were included in the systematic review. These articles were used to describe the main methods used for diagnosis, prevention and treatment of hand neuropathy of cyclists.

CONCLUSION

Despite the range of treatment available for peripheral neuropathies, a unique and common protocol is lacking on this specific topic. For this reason, we delineate a definitive recovery protocol to show the best therapeutic methodologies present in the current literature. Preventive strategies, period of rest since the beginning of the symptomatology, rehabilitation training with muscle strengthening, orthoses at night are the first strategies, but if the symptoms persist, pharmacologic treatment and eventual surgical decompression are sometimes the unique solution.

CT angiography and MRI of hand vascular lesions: technical considerations and spectrum of imaging findings

Vascular lesions of the hand are common and are distinct from vascular lesions elsewhere because of the terminal vascular network in this region, the frequent hand exposure to trauma and microtrauma, and the superficial location of the lesions. Vascular lesions in the hand may be secondary to local pathology, a proximal source of emboli, or systemic diseases with vascular compromise. In most cases, ischaemic conditions are investigated with Doppler ultrasonography. However, computed tomography angiography (CTA) or dynamic contrast-enhanced magnetic resonance angiography (MRA) is often necessary for treatment planning. MR imaging is frequently performed with MRA to distinguish between vascular malformations, vascular tumours, and perivascular tumours. Some vascular tumours preferentially affect the hand, such as pyogenic granulomas or spindle cell haemangiomas associated with Maffucci syndrome. Glomus tumours are the most frequent perivascular tumours of the hand. The purpose of this article is to describe the state-of-the-art acquisition protocols and illustrate the different patterns of vascular lesions and perivascular tumours of the hand.

Ulnar Neuropathy in Cyclists

The form and function of the cyclist exposes the ulnar nerve to both traction and compressive forces at both the elbow and wrist. Prevention of ulnar neuropathy and treatment of early symptoms include bike fitting, avoidance of excessive or prolonged weight-bearing through the hands, and the use of padded gloves. For persisting or progressive symptoms, a thorough history and physical examination is essential to confirm the diagnosis and to rule out other sites of nerve compression. The majority of compression neuropathies in cyclists resolve after appropriate rest and conservative treatment; however, should symptoms persist, nerve decompression may be indicated.