“Million dollar nerve” magnetic resonance neurography: first normal and pathological findings

• Main Author: Silva, Jonadab dos Santos
• Publication Date: 2022
• Other Authors: Barros, Larissa Fidalgo Pereira de, Souza, Renan de Freitas, Mendonça, Silvana Machado, Costa, Flávia Martins, Landeiro, José Alberto, Lopes, Fernanda Cristina Rueda, Acioly, Marcus André
• Format: Article
• Language: eng
• Source: Repositório Institucional da Universidade Federal Fluminense (RIUFF)
• Download full: http://app.uff.br/riuff/handle/1/29206
• topic: Carpal tunnel syndrome; Magnetic resonance imaging; Median nerve; Peripheral nervous system diseases; Síndrome do túnel carpal; Espectroscopia de ressonância magnética; Neuropatia periférica; Carpal tunnel syndrome; Magnetic resonance imaging; Median nerve; Peripheral nervous system diseases

Objectives: To evaluate prospectively the feasibility of magnetic resonance neurography (MRN) in identifying the anatomical characteristics of thenar muscular branch (TMB) of the median nerve, also known as the “million dollar nerve”, in patients and controls. Methods: Thirteen patients affected by carpal tunnel syndrome (CTS) and four healthy controls had their hands scanned on a 3T MR imaging scanner for TMB visualization. Median nerve anatomical variations were classified into four groups according to the Poisel’s classification system modified by Lanz. TMB signal intensity and diameter were assessed for the diagnosis of neuropathy. Results: TMB was successfully identified in all patients and subjects by using MRN. The most suitable pulse sequences to identify and measure nerve diameter were 3D DW-PSIF and T2-FS-TSE. The axial oblique and sagittal oblique planes are complementary in demonstrating its entire course. TMB had mostly an extraligamentous course with radial side origin (93.8%, each). All patients experienced increased T2 signal intensity (P < 0.001) and thickened nerves. Mean TMB diameters were 1.27 ± 0.21 mm (range, 1.02–1.74 mm) and 0.87 ± 0.16 mm (0.73–1.08 mm) (P = 0.008) in the patient and control groups, respectively. Conclusion: MRN is a reliable imaging technique for identification and anatomical characterization of TMB in patients affected by CTS. This innovative imaging workup may therefore be included in the preoperative evaluation of patients scheduled for carpal tunnel release, especially in CTS with TMB involvement or even in isolated TMB neuropathy