Ulna Nerve Compression
Compression of the ulna nerve most commonly happens at the level of the elbow. This is Called cubital tunnel syndrome and the patient will have symptoms of numbness or tingling sensation as if they hit their funny bone. Classically, the patient complains of numbness within the small and ring fingers. In addition, if left untreated and this becomes more advanced, the patient develops significant weakness within the hand as well as atrophy within the fine muscles of the hand causing a clawing phenomenon.
The diagnosis of cubital tunnel syndrome is made again by electro diagnostic studies which reveal a slowing of a conduction velocity of the ulna nerve across the level of the elbow. In addition, studies of the muscle innervated by the ulna nerve can demonstrate significant denervation which is demonstrated by atrophy in the hand and gross weakness of the hand. Treatment in earlier stages consists of splinting, anti-inflammatories and/or the use of iontophoresis.
For advanced cases, these would need a neurolysis, i.e., freeing up scar around the nerve as well as a transposition of the nerve at the site of compression. Postoperatively, if this was the case, the patient is immobilized for approximately 8 days in a splint and then begins gradual therapy for the arm. Range of motion exercises are begun at day 8 and heavy lifting is avoided for approximately 2 months. However, the patient can use the arm for all light activities after day 8. A second less common site of compression of the ulna nerve occurs in the wrist at the level of the Guyon's Canal. Here, the most common cause of compression of the ulna nerve is a ganglion cyst present in this tight canal.
Diagnosis is often made by physical examination and/or an MRI which demonstrates this mass causing compression of the ulna nerve. Other causes of compression of the ulna nerve in the hand include an aneurysm of the ulna artery as well as fractures about the level of Guyon's Canal. A common fracture seen in golfers, tennis players and baseball players is a hook of the hamate fracture. This type of fracture can cause significant swelling and compression of the ulna nerve within the canal. Treatment classically involves either resecting the offending ganglion and/or aneurysm, decompressing the nerve and/or excising the fragment of the hamate bone as well as decompressing the nerve. Postoperative course includes a soft dressing for approximately 2weeks with immobilization of the wrist and a subsequent period of therapy when the sutures are removed at approximately 2 weeks.