Ulnar nerve decopression

Introduction

Several surgical options are available for ulnar nerve decompression.

• Decompression in situ

• Medial epicondylectomy

• Anterior transposition

  • Subcutaneously

  • Intramuscularly

  • Submuscularly

The relative benefits and efficacy of the various techniques have been difficult to compare.

As a rule of thumb simple decompression in situ is best initially.

Consider anterior transposition if the bed of the cubital tunnel is involved/ scarred or if metalwork is in close proximity and likely to impinge on the nerve

Decompression in situ

Anatomy

Considerations

Tourniquet high on arm

Positioning

Skin Incision

Small incision, beginning at a midpoint between the olecranon and the medial epicondyle and extending 6-8 cm distally over the flexor carpi ulnaris.

Superficial dissection

Decompression in situ is accomplished by incising the Osborne ligament and opening the tunnel beneath the 2 heads of the flexor carpi ulnaris by incising the fascia holding them together.

Continued release proximally into the epicondylar groove is discouraged because of the possibility of nerve subluxation occurrence.

Deep dissection

Exposure extension

Closure

Subcuticular if possible

Post operatively

With decompression in situ, no postoperative immobilization is necessary, and active motion is started immediately according to patient tolerance.

Within 1-2 months, full activity should be resumed.

Ulnar nerve transposition

Decompression with anterior transposition

Three types of transposition are possible, each with its own set of advocates.

• Anterior transposition

  • Subcutaneously

  • Intramuscularly

  • Submuscularly

Subcutaneous ulnar nerve transposition yields predictably good results in a majority of patients in several studies.

In 1980, Eaton et al. reported the results of a procedure in which the ulnar nerve was stabilized in the anterior position with a fasciodermal sling.

Indication

Where the normal ulnar nerve bed is scarred or prominent metalwork is present.

Decompression with anterior transposition removes the nerve from its compressive bed and puts it in one that is more suitable.

By transferring the nerve anteriorly, it effectively lengthens the nerve, decreasing tension on it in flexion.

Anatomy

Considerations

Tourniquet high on arm

Positioning

Skin Incision

A curvilinear 10 cm incision is made midway between the epicondyle and the olecranon.

As skin flaps are developed in the deep layer of subcutaneous tissue, one or more branches of the medial brachial and antebrachial cutaneous nerves are variably located, and they must be preserved during the blunt dissection. If they are injured, numbness and neuroma over the olecranon and medial epicondyle may develop.
 

Superficial dissection

Subcutaneous transposition

Subcutaneous transposition is the most commonly used method of transposition because it is easy to perform and results are good. The nerve is positioned beneath the subcutaneous tissue and held to the muscle fascia with a few sutures through the epineurium or a fasciodermal sling.

The preferred method is to construct a fasciodermal sling based laterally, passing it under the nerve and then suturing it to the subcutaneous tissue.

The medial epicondyle is marked as a reference point on the elbow, which is flexed to 45 degrees. At a point one to one and one-half centimeters anterior to the medial epicondyle, a second mark is made to indicate where the fascial sling will be sutured to the deep dermis because once the incision is made the skin retracts, distorting the reference points.

The ulnar nerve is readily palpable proximal to the cubital tunnel, where it lies posterior to the medial intermuscular septum. As the nerve is dissected distally, care must be taken to retain the accompanying longitudinal venae comitantes, thereby preserving critical longitudinal blood supply to the nerve, especially since certain small segmental vessels must be sacrificed to allow for anterior transposition of the nerve. Attempts to preserve as much of the segmental blood supply as possible should be made.

Nestled under the posterior aspect of the intermuscular septum is a plexus of veins, which should be dissected from the septum prior to its excision or cauterized.

Approximately three centimeters of the distal septum should then be excised.
At times, a focal constriction of the nerve within the cubital tunnel may be found; if it is, any superficial fibrotic epineurium can be teased apart to relax the constriction.

The clinical efficacy of doing so is not known, however.

Dont perform an internal neurolysis.

Once the transverse retinacular fibers forming the fascial roof of the cubital tunnel have been released, dissection is carried distally to the level at which the nerve enters the flexor carpi ulnaris.

At or distal to this hiatus between the humeral and ulnar heads of the flexor carpi ulnaris, a transverse arc of fascia may be found and should be divided.

Care must be taken to preserve the small motor branches at the proximal aspect of the flexor carpi ulnaris muscle origin. The fascia and muscle are split at a sufficient distance to prevent the creation of more than a 45-degree angle in the transposed nerve when the elbow is extended. As the nerve is mobilized and is moved from its native position to its transposed position, avoid any traction on it.

The fascia overlying the flexor-pronator origin is cleared of adherent subcutaneous tissue, and a one and one-half-centimeter-wide and two-centimeter-long fascial flap based at the tip of the medial epicondyle is elevated from the muscle. If any vertical intermuscular septae are present, they are released to eliminate any sharp edges upon which the nerve will ultimately rest. No trough is made across the flexor-pronator mass. The nerve is transposed, and the fascial sling is sutured to the sturdy deep dermal tissue with 3-0 absorbable suture. With the skin stretched back toward its original position, the position of the nerve and its fasciodermal sling is evaluated through the full arc of elbow motion. Adjustments in the dermal attachment are rarely necessary.

Submuscular transposition

In submuscular transposition, the origin of the flexor-pronator muscle group must be released. This can be accomplished in a number of ways, and the most important part of any of these releases is to be able to reattach the muscle origin securely. Once the nerve has been transposed to its new bed deep to the flexor pronator muscle group and on the brachialis muscle, the flexor carpi ulnaris fascia is closed, as is the roof of the epicondylar groove.
 

Intramuscular transposition

In intramuscular transposition, once the ulnar nerve has been freed proximally and distally, it is laid across the flexor pronator muscle group to ensure that no kinks are present in the new path of the nerves. Then, a gutter is cut in the muscle, and the nerve is gently placed in this gutter. The fascia is sutured over the nerve to hold it in place.
 

Deep dissection

Exposure extension

Closure

Subcuticular if possible

Post operatively

Bradford et al showed postoperatively their is no need to restrict patients movement.

They suggested:

All patients should be instructed to begin gentle, progressive use of the involved upper limb as tolerated, including an active range of motion.

Avoid forceful use of the involved arm, including manual labour, heavy lifting, and sports involving use of the upper limb, until six weeks after the surgery, at which time all activity restrictions are eliminated.

References

Eaton, R. G.; Crowe, J. F.; and Parkes, J. C., III: Anterior transposition of the ulnar nerve using a non-compressing fasciodermal sling. J. Bone and Joint Surg., 62-A: 820-825, July 1980

Bradford T. Black, O. Alton Barron, Peter F. Townsend, Steven Z. Glickel, and Richard G. Eaton
Stabilized Subcutaneous Ulnar Nerve Transposition with Immediate Range of Motion : Long-Term Follow-up
J. Bone Joint Surg. Am., Nov 2000; 82: 1544.

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Last updated 11/09/2015