The Guyon’s canal in perspective: 3-T MRI assessment of the normal anatomy, the anatomical variations and the Guyon’s canal syndrome

Abstract

(1) To revisit the anatomical boundaries of the canal, its contents and its two channels, (2) to describe the anatomical variations of the canal's borders and the variations of its contents, and (3) to discuss the clinical relevance of the Guyon's canal syndrome. Two hundred and fifty MR wrists examinations were reviewed. MR spin echo T1-weighted axial slices were used to analyze the Guyon's canal. The anatomical boundaries, the cross-sectional area and length of the canal were calculated. The anatomical variations of the canal's walls and contents and their prevalence were sought. Changes related to Guyon's canal syndrome were also evaluated. From the 250 wrists, the anatomy of the Guyon's canal was normal in 168 (67.2%) wrists; 73 (29.2%) wrists presented with anatomical variations; and 9 (3.6%) wrists had derangements causing Guyon's canal syndrome. The cross-sectional area of the canal was 33 ± 11 mm² proximally and 45 ± 19 mm² distally. The canal's length was approximately 40 ± 4 mm. Among the 73 wrists with anatomical variations, there were aberrant muscles in 39 (53.4%) wrists, multiple ulnar nerve branching in 22 (30%) cases, increased amount of fat tissue inside the canal in 9 (12.3%) cases and hypoplastic hamulus in 3 (4.1%) cases. There were 9 (3.6%) symptomatic wrists with clinical and radiological features attributed to Guyon's canal syndrome. MRI is an excellent modality for the evaluation of the Guyon's canal.