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A B M P m e m b e r s e a r n F R E E C E a t w w w. a b m p . c o m / c e b y r e a d i n g M a s s a g e & B o d y w o r k m a g a z i n e 95 motor fibers. As a result, compression of the superficial branch usually produces mixed motor and sensory symptoms, while compression of the deep branch generally produces motor impairment with very few sensory symptoms. Clarifying Guyon's Canal Syndrome Guyon's canal syndrome is classified according to where the compression occurs. The original and most common classification was published in a paper by Shea and McClain in 1969. 3 They describe three types of ulnar nerve compression (Image 4). Type I involves compression prior to the separation of the deep and superficial branches. Because this location includes fibers from both the deep and superficial branches, the symptoms include a mix of motor and 2 3 4 sensory impairment. Type II involves compression of the deep motor branch after it has separated from the superficial branch. Because the deep motor branch contains almost exclusively motor fibers, the primary symptoms from compression in the Type II version are atrophy and weakness in thumb and hand muscles. The adductor pollicis is one of the larger muscles supplied by this deep branch of the ulnar nerve. Weakness or atrophy in this muscle may be apparent by a decreased size or hollowing out of the thenar aspect of the palm. Muscle weakness in the adductor pollicis can also be tested with the Froment's sign (described on page 97). Compression of motor fibers in the Type II version is the most common of these three variations. Therefore, it is more common to see patterns including muscle weakness with a lesser degree of sensory symptoms for most cases of Guyon's canal syndrome. Type III compression occurs near the distal end of the canal and affects the superficial sensory branch, and symptoms are generally paresthesia, numbness, or sharp pain sensations in the ulnar aspect of the hand or the last two fingers. Clients may complain of neurological sensations throughout the entire hand. Mechanical factors that lead to median nerve compression in CTS may also affect the ulnar nerve in Guyon's canal. In these cases, neurological sensations are felt throughout the entire palmar aspect of the hand. 4 If symptoms are being felt in both the median and ulnar nerve distributions of the hand, it is important to address potential entrapment locations of both the median and ulnar nerves. WHAT CAUSES GUYON'S CANAL SYNDROME Median nerve compression in CTS is often created by inflammation of structures within the tunnel, and the majority of cases involve intrinsic (compression from within the tunnel) pressure. The majority of Guyon's canal syndrome cases appear to occur from This image depicts the palmar carpal ligament as the roof of Guyon's canal. Image is from 3D4Medical's Complete Anatomy application. Distal branches of the ulnar nerve. Image is from 3D4Medical's Complete Anatomy application. Three locations of compression for ulnar nerve branches. Image is from 3D4Medical's Complete Anatomy application. Guyon's canal Palmar carpal ligament Type I Type II Type III Superficial branch Deep branch