Orthopaedic Surgery/Cubital Tunnel Syndrome
|Cubital Tunnel Syndrome|
|<<Ulnar Nerve Compression||Ulnar nerve Syndrome>>|
The second most common peripheral nerve compressive neuropathy, cubital tunnel syndrome has unique features clinically and anatomically which make it a more challenging problem to deal with.
From the standpoint of surgical intervention there are minimalists who favor in situ decompression and there are are those who might be characterized as traditionalists who favor submuscular transposition. The other options are intermediate, consisting of epicondylectomy, anterior subcutaneous transposition, usually accompanied by a fascial sling. Then there is the hybrid operation of sort which is referred to as an intramuscular transposition in which rotated flaps of muscle fascia form the roof of the tunnel, the floor is the fleshy muscle bellies left attached, while fibrous bands that might produce kinking or compression of the nerve within the muscular bed are released. With all the transposition options it has become customary to excise the distal aspect of the medial intermuscular septum. This tissue may be left attached distally and use to augment a fascial sling for a subcutaneous transposition, or the fascial roof of a submuscular or intramuscular transposition. When the flexor pronator origin is taken down it is desirable to reconstruct in a fashion that will allow for early motion at least through a limited arc to promote gliding of the nerve in its new bed and to avert stiffness in the elbow.
From the standpoint of diagnostic criteria and surgical intervention there are those who contend that unless there are electical studies to document the problem then it is not cubital tunnel syndrome and certainly not a problem to be addressed by surgical intervention to decompress the ulnar nerve.
From the standpoint of pathophysiology there are those who consider this a nerve compression and those who emphasize the importance of local strain as a potential souce for symptoms. In the latter case, this is considered an additional rationale for anterior transposition over any method which may leave the nerve posterior to the flexion axis of the elbow where it will remain subject to more strain.
Causation with regard to work relatedness can be controversial and especially in cases wherein electrodiagnostic studies are negative but symptoms severe. A contentious situation can arise leading to protracted work loss and litigation. The situation is more difficult because an appropriately cautious surgeon will be reticent to embark upon surgical intervention in the absence of objective verification in the form of an abnormal electical study. The prudent surgeon will recognize that surgery for cubital tunnel has a mixed track record for success. In the event of an unsatisfactory outcome with surgical intervention followup electordiagnostic studies and likely and not unexpectedly may indeed show changes after a surgery where none were present before. This is liable to be characterized as an iatrogenic worsening of the condition. Despite this and other hazards having to do with the medico-legal and social issues surrounding the problem, it is widely held that early surgical intervention for cubital tunnel is associated with a more favorable outcome than late surgery. Ultimately insight in patient selection in conjunction with sound technique will allow successful navigation of these hazards.
The spectrum of clinical manifestations include patients with discreet sensory manifestations in the ulnar nerve distribution reporting diminished sensation in the small finger, ulnar half of the ring finger and the dorsal ulnar aspect of the hand. Other patients report mainly pain or an ache along the medial forearm, and poorly localizing tingling in the hand. Weakness can be due to pain or to the denervation of hand intrinsics and the FDP to the small finger. Pain as a dominant feature tends to lessen with greater severity.
The differential diagnosis becomes problematic as patients may describe pain at the shoulder or base of the neck, and sensory manifestations in the forearm. Both of these features invoke consideration of a cervical radiculopathy or neurogenic thoracic outlet, however either can accompany cubital tunnel with a retroaxonal pain pattern and forearm sensory manifestations due to direct irritation of the medial brachial or antebrachial cutaneous nerves. The latter may be especially likely wherein the pathological process is instigated by blunt trauma, or pathological subluxation of the ulnar nerve about the medial epicondyle.
In a significant minority of patients upper extremity complaints do not confine themselves to a single source. The first task for the surgeon is to discern what combination of pathologies are responsible for the complaints, which are linked and which are discreet and which might be reasonably addressed together, and which are best treated separately. Cubital tunnel commonly occurs in conjunction with carpal tunnel syndrome, or with tendinopathy of the common extensor origin. While it may be prudent to address the problems individually it is tempting to combine procedures to resolve the problem in one sitting. The latter approach requires keen insight or luck in selecting the right patient who can recover efficiently from a combined operation. The concern is that a morass of symptoms may be attibuted to multiple compressive neuropathies and tendinopathies when in fact they are manifestations of a pain syndrome which is only aggravated by an ill conceived surgical intervention made all the worse by a multi-sight surgery. The desire to resolve the problem in one blow may be well intentioned, and is appealing for its potential efficiency from the standpoint of cost and down time, but if the surgery fails a nightmare of protracted disability can ensue.