Ultrasound and EMG-NCV study (electromyography and nerve conduction velocity) correlation in diagnosis of nerve pathologies

Abstract

Purpose: Nerve disorders are commonly encountered in clinical practice. Ultrasonography (USG) is a useful modality in the evaluation of most of the peripheral and superficial pathologies amenable to penetration by ultrasound. The primary objective is to study the USG findings of various peripheral nerve pathologies and to correlate them with electrophysiological (EMG-NCV) findings.

Method: 42 patients referred with suspicion of peripheral nervous system affection were evaluated with USG along with EMG-NCV. After reviewing detailed anatomy of the region, the affected nerve was visualized along the major neurovascular bundle or at a known anatomical landmark with a high-frequency (9-20 MHz) linear/hockey stick transducer.

Results: The USG parameters, namely loss of fibrillary pattern, hypoechogenicity and nerve thickening, showed significant p value (p < 0.05) on the tests of significance, suggesting these parameters are significant predictors of nerve affection/pathology on USG. Each ultrasound parameter was correlated individually with SNAP and CMAP. The results revealed positive correlation of echogenicity (r = 0.210, p = 0.05), fibrillary pattern (r = 0.209, p = 0.05) and thickening (r = 0.387, p < 0.05) with sensory nerve action potential (SNAP) and compound muscle action potential (CMAP).

Conclusion: USG can be used as corroborative investigation to strengthen the findings of EMG-NCV. This combination represents a powerful tool in enabling appropriate planning for treatment, preventing unnecessary intervention and thus improving overall outcomes in patients with peripheral neuropathy.

Keywords: CMAP; EMG–NCV; Nerve; SNAP; Trauma; Ultrasound.

Fig. 1

Bar diagram showing the nerves and plexuses involved (frequency and percentage) in the study

Fig. 2

Normal appearance: a USG image of a peripheral nerve (ulnar)—The hypoechoic nerve fibrils with surrounding echogenic interfascicular perineurium and hyperechoic covering (epineurium). b The normal left ulnar nerve in transverse section reveals small hypoechoic areas (nerve fascicles) separated by hyperechoic septae (interfascicular perineurium) giving a “honeycomb” appearance. c The longitudinal section of right median nerve at elbow reveals parallel hypoechoic bundles, the fascicles separated by hyperechoic lines—the perineurium giving a “bundle of straws” appearance. The outermost echogenic covering represents the epineurium. d The longitudinal section of right ulnar nerve just distal to elbow

Fig. 3

Normal appearance: a USG image of left C4 to C6 roots in longitudinal section. b Axial section of right brachial plexus showing cords in axilla lateral (1), medial (2) and posterior (3) in relation to axillary artery. Cords do not fascicular architecture

Fig. 4

Bar diagram showing the age distribution (frequency and percentage) in the study

Fig. 5

Bar diagram showing the diagnoses (frequency and percentage)

Fig. 6

Trauma: a the longitudinal section of the right ulnar nerve reveals post-traumatic near complete transection with a neuroma within. The epineurium is intact. b The longitudinal section reveals post-traumatic complete transection of the right ulnar nerve with retraction of the torn ends with neuroma

Fig. 7

Trauma: a longitudinal section of USG image shows post-traumatic near complete transection of left ulnar nerve in the distal arm, retraction of cut ends. b Longitudinal section—near complete transection of left median nerve in the proximal forearm, retraction of cut ends and neuroma. c Axial section showing neurapraxic injury of left median nerve seen as swollen nerve with hypoechoic appearance. d Longitudinal section showing transection of ulnar nerve with retraction of cut ends and entrapment within the scar. e Axial section—transection of left median nerve in the distal arm, retraction of cut ends, entrapment within the scar and neuroma. f Longitudinal section—neuroma involving C7 nerve root

Fig. 8

Hansen’s disease: a axial section—neurapraxic injury of left median nerve seen as swollen nerve with hypoechoic appearance. b Axial section—neuromas involving C6, C7 nerve roots

Fig. 9

Hansen’s disease: a In distal arm, the longitudinal section shows enlarged hypoechoic left ulnar nerve with loss of fascicular pattern and intraneural abscess formation. b Axial section—enlarged left ulnar nerve at elbow with loss of fascicular pattern and intraneural abscess formation. c Axial section—in leg-enlarged left superficial peroneal nerve with loss of fascicular pattern and intraneural abscess formation. d Longitudinal section—enlarged right ulnar nerve at elbow with loss of fascicular pattern, intraneural abscess formation and perineural fat stranding. e Longitudinal section—enlarged right ulnar nerve at elbow with loss of fascicular pattern, intraneural abscess formation and perineural fat stranding

Fig. 10

Hansen’s disease: a longitudinal section—enlarged right ulnar nerve at distal forearm with loss of fascicular pattern, intraneural abscess formation and perineural fat stranding. b Axial and Longitudinal section—enlarged right median nerve in distal forearm with loss of fascicular pattern, intraneural abscess formation and perineural fat stranding. c Axial section—enlarged right ulnar nerve in elbow with loss of fascicular pattern, intraneural abscess formation and perineural fat stranding. d Longitudinal section—enlarged right ulnar nerve at elbow with loss of fascicular pattern, intraneural abscess formation and perineural fat stranding

Fig. 11

Hansen’s disease: a panoramic view in longitudinal section—enlarged right ulnar nerve in arm with loss of fascicular pattern, intraneural abscess formation and perineural fat stranding. b Longitudinal section—enlarged right ulnar nerve at elbow with loss of fascicular pattern, intraneural abscess formation and perineural fat stranding. c Longitudinal section—in leg shows enlarged left superficial peroneal nerve with loss of fascicular pattern and intraneural abscess formation

Fig. 12

Nerve sheath tumour a longitudinal section showing nerve sheath tumour involving right ulnar nerve in distal forearm. Second image shows the nerve fascicles separately in the inferior portion of the nerve diagnosed as schwanomma. b Axial section showing right ulnar nerve sheath tumour—schwanomma in distal forearm. c Axial section—first image shows a mass lesion involving left C7, T1 nerve roots, and second image is a magnified view of the lesion diagnosed as a neurofibroma. d Axial image at the level of base of neck showing a mass lesion seen just adjacent to the right common carotid artery, later diagnosed as vagal schwanomma. e First image—axial image at the level of base of neck—a mass lesion seen just adjacent to the right common carotid artery later diagnosed as vagal schwanomma. Second image longitudinal section showing vagal nerve. f Axial image at the level of base of neck—a vagal schwanomma seen just adjacent to the right common carotid artery, within the carotid sheath

Fig. 13

Work up for peripheral nerve pathologies