Ulnar

Title: Submuscular Ulnar Nerve Transposition at the Elbow.
Published: 4/11/2011, Updated: 4/11/2011.

Author(s): Susan E. Mackinnon MD, Andrew Yee BS.
Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO.

There is currently no evidence that any single operative procedure is “the best” for the management of cubital tunnel syndrome. However, our institution has stressed that the success of any described surgical techniques, for the management of cubital tunnel syndrome (CTS), is dependent on not creating a new compression point proximal or distal to the ulnar nerve decompression/transposition. Following a transposition, the ulnar nerve could be compressed at the medial epicondyle with a too-tight of a flip. In decompression and transposition procedures, it is important to ensure early range-of-movement to facilitate neural gliding. Failure at identifying and releasing all compression points at the cubital tunnel will result in recurrent CTS symptoms. The submuscular ulnar nerve transposition is the choice ulnar nerve procedure of our institution for management of cubital tunnel syndrome. In our experience, this procedure has not resulted in any recurrences of CTS symptoms, given that there is a recurrence rate with a simple decompression and a submuscular ulnar nerve transposition. The submuscular ulnar nerve transpositions completed by our institution can be further described as an intramuscular transposition with step-lengthening of the flexor-pronator muscles. In addition, to prevent any possible distal compression points during nerve regeneration within the hand, the submuscular ulnar nerve transposition is accompanied by a Guyon’s canal release and the decompression of the deep motor branch.

Extended Version

Surgical Tutorial – Submuscular Ulnar Nerve Transposition. A submuscular ulnar nerve transposition is performed to decompress the ulnar nerve in the cubital tunnel at the elbow. The medial antebrachial cutaneous nerve is identified and protected. Proximally, the medial intermuscular septum is resected. A step-lengthening of the fascia of the flexor-pronator muscles is performed. The ulnar nerve is placed in a transmuscular location. More importantly, the distal fascial septum between the flexor carpi ulnaris and the flexor-pronator muscles is removed.

Surgical Techniques

PROCEDURE: Submuscular Ulnar Nerve Transposition at the Elbow.

Incision Description:

• The incision is marked behind the medial epicondyle in line with the ulnar nerve.
• The use of a sterile tourniquet will provide a bloodless operative field, but will hide a possible proximal compression site from the Struther’s band when it exists. The tourniquet can be removed and the band addressed directly, as it is located directly underneath the tourniquet.

Surgical Steps:

Exposure and Dissection:

1. Incise skin and dissect through subcutaneous tissue.
2. Protect the crossing branches of the medial antebrachial cutaneous nerve. It is located 3.5cm distal to the medial epicondyle.
3. Palpate the medial intramuscular septum and identify the ulnar nerve just below.

Ulnar Nerve Submuscular Transposition:

1. Decompress the ulnar nerve through the cubital tunnel.
2. Elevate the soft tissue above the flexor-pronator muscle fascia.
3. Identify and remove the medial intramuscular septum found proximal to the cubital tunnel.
4. Mark the step-lengthening pattern on the fascia of the flexor pronator muscle origin and elevate the two fascia flaps. Be sure the flaps are long enough to prevent tension on the ulnar nerve.
5. Identify the “T-shaped” fascia in the mid-portion of the flexor-pronator muscle origin and resect it. Be sure to not go too deep or else you will be in the elbow joint.
6. identify the fascia between the ulnar-innervated flexor carpi ulnaris and the median-innervated muscles and remove the fascicle. Always divide the fascial bands away from the medial epicondyle first and then resect them.
7. Divide the flexor-pronator muscles proximally down to the level of the brachialis.
8. Divide the more distal flexor-pronator muscle only as deep as you need to go in order to have a complete straight-line position of the ulnar nerve in the transposition site.
9. Neurolyse the posterior motor branches that tether the ulnar nerve posteriorly to allow a good anterior transposition of the ulnar nerve without tension.
10. Close the fascial flaps very loosely over the ulnar nerve.
11. Using your finger, run it proximally and distally to be sure that there is no proximal or distal compression points. Pay special attention distally to make sure that there is no fascial band that is kinking the ulnar nerve in the distal-most aspect of the transposition site.

Title: Guyon’s Canal Release of the Ulnar Nerve and Decompression of the Deep Motor Branch.
Published: 4/11/2011, Updated: 4/11/2011.

Author(s): Susan E. Mackinnon MD, Andrew Yee BS.
Division of Plastic and Reconstructive Surgery, Washington University School of Medicine, St. Louis, MO.

The decompression of the ulnar nerve through Guyon’s canal is a well-known procedure; however the decompression of the deep motor branch of the ulnar nerve is not. Lister, G.D. has stated to the senior author that the decompression of the deep motor branch of the ulnar nerve in Guyon’s canal was a procedure that even challenged trained hand surgeons. The senior author has agreed to this statement and has had the opportunity to “redo” Guyon’s canal releases and found in every case that the deep motor branch has not been decompressed. The reason that hand surgeons are challenged with decompression of the deep motor branch is that the branch is not visualized until after it has been completely decompressed. Typically, the sensory component of the ulnar nerve is easily visualized through Guyon’s canal for decompression, but in many circumstances, the compression point of the deep motor branch by the hypothenar muscles is not addressed. This will result in relief of ulnar nerve-related pain, but weakness will persist in intrinsic muscles of the ulnar nerve. In the face of incorrect depiction of the anatomical course of the deep motor branch by reputable literature sources, the deep motor branch requires correct knowledge of its anatomical course in order to achieve a successful decompression.

Besides the deep motor branch, there exist other surgical nuances that are important to a successful Guyon’s canal release. An additional main entrapment on the ulnar nerve, besides the palmar carpal ligament that composes the roof of Guyon’s canal, is the antebrachial fascia proximal to Guyon’s canal in the distal forearm. This fascia can be thick and compressive for a distance of approximately a centimeter in many patients. In terms of other surgical nuances, there is a small cutaneous nerve that branches from the sensory component of the ulnar nerve that innervates a small cutaneous area of the palm. This cutaneous nerve branch is typically found 2.5cm distal to the wrist crease and 1cm ulnar to the thenar crease. This cutaneous branch must be protected during the Guyon’s canal release. In the past decade, the senior author has found increasingly that patients with cubital tunnel and motor complaints of clumsiness, loss of dexterity, and certainly anyone with ulnar intrinsic weakness will benefit not only from an ulnar nerve transposition at the elbow, but also a Guyon’s canal release. With the ability to utilize the scratch collapse test with ethyl chloride, a hierarchy of entrapment points in the ulnar nerve can determine the benefit of the Guyon’s canal release addition to patients with ulnar nerve motor problems and cubital tunnel benefit from Guyon’s canal release.

Extended Version

Surgical Tutorial – Guyon’s Canal Release and Carpal Tunnel Release. The ulnar nerve is decompressed in the wrist through Guyon’s canal and in the hand, specifically the deep motor branch of ulnar nerve. The deep motor branch of ulnar nerve is released by dividing the tendonious arch of the hypothenar muscles. In addition, a carpal tunnel release is performed by transecting the transverse carpal ligament.

Surgical Techniques

PROCEDURE: Guyon’s Canal Release of the Ulnar Nerve and Decompression of the Deep Motor Branch.

Incision Description:

• Incision is marked ulnar to the thenar crease and comes across the wrist in a Brunner’s fashion.

Surgical Steps:

Guyon’s Canal Release and Decompression of Deep Motor Branch:

1. Open Guyon’s canal.
2. Release the thickened antebrachial fascia just proximal to Guyon’s canal.
3. Sweep the neurovascular bundle medially.
4. Palpate the hook of the hamate.
5. Look at the hypothenar muscle and fascia and identify the proximal free border of the hypothenar fascia.
6. Decompress the deep motor branch by dividing the attachment of the hypothenar muscles, staying close to the hook of the hamate.