May 17, 2021
The cause of cubital tunnel syndrome has long been debated. Really the only proven cause is prolonged elbow flexion for hours at a time, sleeping with one’s hands up by her face, particularly sleeping prone, or traumatic with scarring and possible anatomic distortion as with an elbow fracture. The remote possibility of anatomic variation resulting in entrapment of the ulnar nerve up to 6 or 8 cm above the medial epicondyle has resulted in a lot of unnecessary surgical dissection and huge scars. This author has performed about 3,000 cubital tunnel surgeries in the past 34 years. Upon switching to 4.5 loupe magnification, on occasion he would notice a bridge of vessels crossing the ulnar nerve just beneath the carpi ulnaris fascia at the entry to the FCU but distal to the medial epicondyle. In order to avoid postop hematoma or bleeding, once identified, the vessels are clamped with ligaclips and then released. These vessels may be one explained cause for the development of cubital tunnel syndrome and, in particular, persisting symptoms despite getting a person to quit sleeping with the elbow bent with the use of a nighttime splint. Unfortunately, at this time there is really no good way to determine this preoperatively. Upon review of the last few hundred cubital tunnel surgeries I have performed, I have noticed this abnormal anatomy 26% of the time (79 of 299). It brings up the question also as to whether the decompression of the ulnar nerve needs to be done any further than that at entry to the FCU to just above the medial epicondyle.