Ulnar tunnel syndrome is when the ulnar nerve gets compressed at the wrist. The small and ring fingers go numb. The symptoms are very similar to those of cubital tunnel syndrome, but ulnar tunnel syndrome is much less common. These two nerve compression syndromes are therefore often confused. Ulnar tunnel syndrome may be caused by a mass, such as a cyst, or by a fracture of a nearby wrist bone.
The ulnar tunnel, also known as Guyon’s canal, is above the carpal tunnel. The floor of Guyon’s canal is the transverse carpal ligament, which is also the roof of the carpal tunnel. So an endoscopic carpal tunnel release can release the ulnar tunnel as well.
Ulnar tunnel syndrome is often diagnosed on nerve conduction studies. If there is no mass present in the ulnar tunnel then an endoscopic carpal tunnel release is all you need to cure this. If there’s a mass, then an open approach to Guyon’s canal is needed to remove the mass. That’s why, in cases of ulnar tunnel syndrome, I usually order an MRI before surgery. The MRI can determine if a simple endoscopic carpal tunnel release will be enough, or if more needs to be done to cure ulnar tunnel syndrome. The results of treatment are very good.