Clinical and Ultrasonographic Features of Distal Ulnar Neuropathy: A Review

Abstract

Focal ulnar neuropathy at the wrist is a rare but problematic disorder often associated with the unique anatomy of this nerve as it courses through Guyon's canal, a superficial fibro-osseous tunnel in the proximal ulnar palm. The electrophysiologic features of this disorder have been well-characterized, but the sonographic anatomy of the nerve across the wrist and palm has yet to be systematically described in normal and abnormal states. In this review, we describe the basic anatomy and the sonographic appearance of the nerve in the wrist and palm in normals and individuals with pathology. The value of using US in conjunction with electrodiagnostic testing is emphasized as the two tests together provide critical information regarding etiology, predisposing factors, and functional significance. Furthermore, ultrasound is useful as a patient educational tool to promote behavioral changes that assist in nerve recovery when pathology is related to repetitive stress.

Sonoanatomy of the deep branch of the ulnar nerve

“…This highlights the role of HRUS in diagnosing or even localizing abnormal nerve conditions of the DBUN by detecting changes in the CSA. Sonographic quantification of the CSA is crucial in diagnosing peripheral neuropathies . In fact, there was one patient with ulnar neuropathy of the wrist (type 3) that was confirmed by electrodiagnostic study in our clinic.…”

“…The usefulness of HRUS in detecting the DBUN and scanning its course has been confirmed in recent studies. 11,12 Some studies analyzed surgical approaches and its complications in open carpal tunnel release and percutaneous pinning for carpal metacarpal fracture dislocations to prevent iatrogenic DBUN injury. 8,9 The sonoanatomy of the nerve provides more detailed information that may limit nerve damage during various hand procedures.…”

Progressive Ulnar Neuropathy due to anomalous Distal Forearm Muscle: Distal Forearm Decompression

“…Rarely, ulnar neuropathy may be caused by proximal compression by aneurysms, hematomas, crutches, or medical tourniquets. 3 …”

“… 1 A cadaveric study of 58 wrists demonstrated a 22.4% incidence of anomalous muscles in this region, 2 with the most common muscle anomaly being an accessory abductor digiti minimi. 3 An accessory palmaris longus comprised only 8.6% of the anomalies. 4 Typically, symptoms of ulnar neuropathy begin with sensory deficits, such as numbness and tingling of the little and ring fingers, followed by intrinsic motor deficits as the neuropathy progresses.…”

Hand and Wrist Neuropathies: High-resolution Ultrasonography and MR Neurography

“…In the context of so-called cyclist handlebar palsy, 45 US is able to recognize pathologic signs of chronic nerve compression, such as nerve swelling, thickened epineurium, and perineurial soft tissue edema. 46…”