JEAN CASIMIR FELIX GUYON was a French surgical pathologist (later professor of genitourinary surgery) who noticed in 1861 that digital pressure over the proximal hypothenar region of his own hand produced a bulge still more proximally at the volar wrist crease.1 The evanescent swelling was initially considered to be synovial thickening, but cadaver dissection proved it to be a fibrofatty mass arising from an intra-aponeurotic space. Although Dr. Guyon was intrigued primarily by the lump of fibrofatty tissue residing in this "loge" (lodge), he described the course of the ulnar artery and nerve through the region and predicted that compressive difficulties might be clinically anticipated.
Isolated ulnar-nerve motor paralysis in the hand due to occupational trauma was first clearly reported by Ramsey Hunt2 in 1908. Seddon3 and Brooks,4 in 1952, independently drew attention to occult carpal ganglia often being the pressure-producing culprit. In an excellent article
Grantham SA. Ulnar Compression in the Loge de Guyon. JAMA. 1966;197(6):509-510. doi:10.1001/jama.1966.03110060183033