Guyon’s tunnel syndrome develops due to compression of the deep branch of the ulnar nerve in the canal formed by the pisiform bone, hook of the hamate, palmar metacarpal ligament and short palmar muscle. There are burning pains and sensitivity disorders in the IV-V fingers, difficulty in pinching movements, adduction and spreading of the fingers.
Ulnar tunnel syndrome is very often the result of prolonged pressure from working tools, such as vibrating tools, screwdrivers, tongs, and therefore occurs more often in certain professions (gardeners, leather carvers, tailors, violinists, people working with jackhammers). Sometimes the syndrome develops after using a cane or crutch. Pathological factors that can cause compression also include enlarged lymphatic ganglia, fractures, arthrosis, arthritis, aneurysm of the ulnar artery, tumors, and anatomical formations within Guyon’s canal.
The difference between Guyon’s canal syndrome and cubital tunnel syndrome is indicated by the fact that when a nerve is damaged in the hand, pain occurs in the hypothenar region and the base of the hand, as well as intensification and irradiation in the distal direction during provocative tests. Sensitivity disorders with all this occupy only the palmar surface of the IV-V fingers. At the back of the hand, susceptibility is not disturbed, since it is provided by the dorsal branch of the ulnar nerve, which extends from the main trunk at the level of the distal third of the forearm.
In the differential diagnosis with radicular syndrome (C8), it should be taken into account that paresthesias and sensitivity disorders can also appear along the ulnar edge of the hand. Paresis and hypotrophy of the hypothenar muscles are possible. But with C8 radicular syndrome, the zone of sensitive disorders is much larger than with Guyon’s canal, and with all this, there is no hypotrophy and paresis of the interosseous muscles.
If the diagnosis is made early, then activity restriction may help. Patients can be advised to use fixators (orthoses, splints) at night or during the day to reduce trauma.
In case of failure of conservative measures, surgical treatment is carried out, aimed at reconstructing the canal in order to release the nerve from compression.