Cubital Tunnel Syndrome

Pressure-Specific Sensory Device (PSSD)

In 2002 Dr. Ichtertz visited with A. Lee Dellon, M.D., Professor of Plastic Surgery and Neurosurgery at Johns Hopkins University Medical Center and author of over 250 scientific articles. The goal was to gain a full understanding of the technique and application of quantitative sensory examinations using the NMT Pressure-Specific Sensory Device (PSSD) which had been developed and studied in the diagnosis of peripheral neuropathy - most specifically diabetic peripheral entrapment neuropathy and FDA approved. Dr. Ichtertz added this to his clinical armamentarium and has utilized the technology to further enhance the diagnosis and improve the treatment of ulnar nerve entrapment, both nonoperative and operative - specifically cubital tunnel syndrome.

The cause of cubital tunnel syndrome is almost exclusively prolonged - but not repetitious - elbow flexion.

Negative Effects of Elbow Flexing

Studies beginning in the 1950s (see references) confirm that flexing the elbow beyond 40 degrees puts tension and pressure on the ulnar nerve behind the medial epicondyle of the elbow; while the space at the elbow for the nerve in the retrocondylar groove (cubital tunnel) diminishes as the tension increases in the elbow with further flexion.

The most eloquent paper on this topic was published by Seror in the Journal of Bone and Joint Surgery, British Edition, 1992. However, Dr. Dellon at Johns Hopkins has reported the most detailed analysis of a large series of patients. Maximum tension and pressure on the nerve occur when the person's shoulder is elevated away from the body, elbow flexed fully, hands above the head. This position is demonstrated by a person sitting or lying with her hands above their head, elbows flexed, or lying face down with an arm above the head, elbow flexed.

Eliminate Symptoms of Cubital Tunnel Syndrome

Often patients who present with cubital tunnel sit in the office exhibiting this very same maladaptive posture! Multiple researchers have proven that prevention of this posture by use of an elbow splint at night to hold the elbow straight and to gain the cooperation of the patient has about a 7 out of 10 chance of eliminating the symptoms of cubital tunnel syndrome if a person is cooperative and if they present before irreversible nerve damage has occurred. The remaining 3 out of 10 people will go on to require surgical decompression of the ulnar nerve with an expectation of a good to excellent result in 85-90% of the people as long as they don't have muscle wasting at the time of presentation.

Abnormal Artery and Anconeus Epitrochlearis Muscle

Dr. Ichtertz has identified a previously unknown cause of cubital tunnel syndrome, that of an abnormal artery pressing the nerve as it exits out of the cubital tunnel proper into the flexor carpi ulnaris muscle. The artery is actually just beneath the origin of the muscle.

An abnormal muscle has been identified in a variable number of people known as the anconeus epitrochlearis muscle. When this muscle is present, a tight band that is usually directly over the nerve, or arcuate ligament, is usually absent. I believe that the muscle itself may tightly bind the nerve, though this is uncertain. In patients with cubital tunnels with anconeus epitrochlearis, the muscle is released as part of the procedure. It just changes the operative exposure a little bit; nothing else changes.

It is believed that about 1/3 of the patients who have bad enough cubital tunnel syndrome to go on to require surgery will have normal nerve conduction studies because of the limitations in our ability to test the nerves. Generally it is considered that only 5-10% of most patients presenting with carpal tunnel syndrome are not going to be able to be confirmed to have entrapped nerves on nerve conduction study using the best electrodiagnostic technique and equipment.

Diagnosis of Cubital Tunnel Syndrome

The diagnosis of cubital tunnel syndrome is dependent on a keen awareness of it as a possible cause of symptoms and careful clinical examination (local squeezing of the nerve for signs of tenderness, or tingling or burning radiating down into the ulnar side of the hand and forearm), the elbow flexion test which temporarily increases the pressure of the nerve, assessment for weakness of pinch, weakness or decreased ability to abduct and adduct - draw together or place apart the fingers, and in a more advanced case a positive Froment or positive Wartenberg sign which generally would be considered to have a poor prognosis because of the evident muscle wasting that is usually occurring simultaneously. Clawing of the hand is a late and usually essentially irreversible manifestation of untreated, late to present cubital tunnel syndrome.

Variations in Presentation of Cubital Tunnel Syndrome

Do You Need Surgery? 

Surgery for cubital tunnel syndrome is necessary with ongoing symptoms and should be offered in short order to somebody who presents with obvious weakness of pinch and/or grips with demonstrated nerve conduction anomaly confirming nerve entrapment at the cubital tunnel because of the poor prognosis for late treatment of this entity. Additionally, if a person has ongoing symptoms in the absence of weakness, she should still be given the option of surgical decompression if she is unable or unwilling to comply with elbow extension splinting at nighttime. A rare person who fails to benefit from elbow splinting and swears to comply with that means of treatment is noted to have a congenital anomaly which has led to the ulnar nerve entrapment.

Occasionally a childhood injury resulting in a broken elbow (supracondylar humerus fracture) will heal with angular deformity.

This has been much less common in the last 15-20 years because of more aggressive surgical intervention for improved outcome. Angular deformity may cause greater tension on the ulnar nerve at the elbow.

Cause of Cubital Tunnel Syndrome Symptoms Are Unclear

It is unclear what contribution vigorous forceful muscle activity in the upper extremity such as a laborer might contribute to the development of or ongoing symptoms of cubital tunnel syndrome. People who are more physically active at the time of presenting with carpal and cubital tunnel syndrome will tend to complain of more symptoms. It is unclear whether that is in any way actually worsening the problem rather than just making the person aware of the underlying problem. This to a large extent is what is construed as occupational aggravation of the problem under worker's compensation for a minority of patients presenting with either carpal or cubital tunnel syndrome.

The research done on entrapment neuropathy, particularly that not funded by groups primarily benefiting from the outcome of that research; i.e. people receiving multiple NIH grants, etc., tend to suggest that the majority of entrapment neuropathy is age and genetics and possibly general health-related (age over 30, female rate of presentation 2-3 women per men, strong family histories frequently obtainable, much higher rate in diabetics and in the obese). There is no direct link to any occupation with the exception of sorting diamonds or working under a microscope or holding a telephone receiver on a prolonged basis for the development of cubital tunnel syndrome.

Medial Epicondylitis

Medial epicondylitis or "golfer's elbow" is a degenerative condition of the flexor muscle origin in the "medical epicondyle" of the humerus of the elbow. The majority of people presenting with inner elbow pain, however, do not have "medial epicondylitis" which actually implies an inflammatory condition, but they are experiencing the manifestation of entrapment of the ulnar nerve at the cubital tunnel; i.e. a variation in cubital tunnel syndrome. This was proven in research published by Morey and Gabel at the Mayo Clinic. I have verified this also with NCS and Pressure-Specific Sensory Device tests. Medial epicondylalgia (pain at the inner elbow) is the best terminology applied to this until an absolute diagnosis is confirmed by nerve conduction studies. Medial epicondylosis is best treated by corticosteroid injection and avoidance of pressure on the inner elbow along with making certain that the person is sleeping with her elbows extended (straight). Ultimately failure to respond to nonoperative treatment benefits from medical epicondyle removal (medial epicondylectomy), at which time formal ulnar nerve decompression can be carried out to ensure that the symptoms are completely eliminated.

Operative Treatment of Cubital Tunnel Syndrome

Over the years, about seven different operations have been reported and discussed in medical literature regarding surgical treatment of cubital tunnel syndrome. Learmonth, who in my opinion has had a great influence on the misdiagnosis of carpal tunnel syndrome as TOS historically was also the early proponent for submuscular transposition; i.e. moving the ulnar nerve beneath the muscle bed, bringing it away from the inner side of the elbow and away from the stretching and compressing that would occur there. This is probably one of the least performed procedures because it is so aggressive and invasive, and takes so long to heal with weeks off of work and in most hands a large surgical scar. There has been no proven added benefit.

Techniques

In-situ decompression of the ulnar nerve at the elbow is a technique wherein the arcuate ligament directly upon the ulnar nerve is simply released. This has gained a lot of press in the last few years without long-term follow-up. Endoscopic cubital tunnel release was introduced about 1995 by Dr. Tsai at the Kleinert clinic. While his technique has been met with resistance the concept has gained momentum recently. Traditional cubital tunnel surgical options have often left unsightly scars. Depending upon the technique used by each surgeon substantial temporary limitations have also been imposed. For the few of us using science as our guide immediate activity with almost no restriction has been possible. This includes a minimal incision size made possible by operating under magnification.

Two elements appear to be involved in ulnar nerve entrapment at the elbow: a) compression behind the arcuate ligament especially upon bending (flexing) the elbow and b) stretching of the ulnar nerve that also occurs upon elbow flexion. Thus the worst posture a person might assume is face down (prone) while sleeping.

Limited Reports of Success

Only limited reports of successful surgery done in-situ, i.e. decompressing the nerve while leaving it lying in its original position, were available until recently. Those of us determined to achieve the best results have held off on using an in-situ approach fearing poor results because the band compressing the nerve is addressed but not the ongoing problem with stretch. The concern over this has recently been reduced. Dr. Reimer Hoffmann of Germany in a large series The Endoscopic Management of Cubital Tunnel Syndrome. M.Siemionow has demonstrated fine results using his endoscopic approach with facial plastic surgical tools and a fiberoptic scope in over 700 patients in all states of disease from mild to severe. Though not offering convincing data, several other surgeons have been advocating an in-situ approach for years. Only Dr Hoffmann has the data and the truly in-situ technique to back it up. However, the highest failure rate has been reported Washington University of 19% using an in-situ release. This may be because of continual poor sleep positions that continue to stretch the ulnar nerve.

Low Recurrence Rates

Cubital tunnel syndrome has an extremely low recurrence rate once operatively treated. It is so small it has not been accurately determined. Before declaring a person has recurrence of cubital tunnel syndrome, the patient must be given ample time to address their sleeping posture and they must also prove that they do not have entrapment of the ulnar nerve at the wrist level; i.e. Guyon's canal. Recurrence may be more likely to occur in a diabetic than a nondiabetic person. Since September 2009 I have been using an endoscopically-assisted technique in all patients who are lean enough to safely perform it and cooperative enough to ensure its success. I have been impressed by the reduction in postoperative bruising and the minimal discomfort noted by my patients as well as the appropriate elimination or improvement of cubital tunnel symptoms. I require confirmation of improved sleep posture to proceed with in-situ endoscopically-assisted ulnar nerve decompression. This provides a significant advantage to the patient with less post-operative discomfort and faster recovery when compared with other surgical techniques.

There are advocates of early surgical treatment of cubital tunnel syndrome, even for patients with negative electrodiagnostic studies because of the good results that may be achieved while avoiding irreversible deformity and disability.

Our Surgical Treatment Recommendations for Cubital Tunnel Syndrome

Endo-Cubital Decompression

Dr. Ichtertz now advocates in-situ endoscopic cubital decompression for the majority of my patients, as long as the patient is cooperative with correcting elbow posture and does not exhibit severe weakness or muscle atrophy. Prior to 2009, however, he had predominantly performed comprehensive decompression of the ulnar nerve through about a 2-inch incision (obese patients require a slightly larger incision for their own protection) which is placed behind the midline of the inner elbow such as to be invisible most of the time. This outpatient surgery is done preferably under a light general anesthetic or a regional supraclavicular nerve block.

Ulnar Transposition

Regardless of the methodology and surgical treatment, there is a broad range of complaints from most people having very little pain to a very few others complaining vociferously of pain lasting anywhere from a few days to more than six months. It is rare to require medication for pain in the elbow beyond a few days at most.

Athletes And Cubital Tunnel Syndrome

For the most part, an athlete needs to be protected from inner elbow instability. My suspicion is that a lot of people who are undergoing "Tommy John" elbow surgery actually have cubital tunnel syndrome and an integral portion of that surgery involves decompression of the ulnar nerve at the elbow. I have never had to reconstruct the inner elbow because of instability developing as a result of cubital tunnel decompression. I do think that it is a good idea to avoid any weakening of the medial elbow ligaments in the throwing arm of a throwing athlete. Therefore perhaps the best method of decompressing an athlete's cubital tunnel is anterior subcutaneous nerve transposition or the in-situ techique. This involves freeing the nerve of overlying constriction and sliding it forward of the medial epicondyle and securing it in the new location. 

Anterior Interosseous Nerve Transfer

For treatment of late, severe cubital tunnel with muscle weakness with or without atrophy, the technique, anterior interosseous nerve transfer to the ulnar motor branch at the wrist may be beneficial for a small subset of people that come in with marked weakness in association with cubital tunnel syndrome. If it has just occurred over a very short period and preferably before any muscle wasting has occurred, these individuals may benefit from anterior interosseous nerve transfer into the ulnar motor branch at the wrist. This is a relatively minor operation and can be done as an outpatient. It was invented in the mid-1990’s for severe ulnar nerve injury at the elbow or above because it takes so long for the ulnar nerve to recover and muscles are usually wasted away. The anterior interosseous nerve at the level of the wrist can be sacrificed without any deficit because at that point it only innervates the muscle known as the pronator quadratus which does very little for the forearm. By transferring this nerve into the ulnar nerve motor branch at the wrist, coined “supercharging it”, by Susan McKinnon, MD, plastic surgeon at Washington University in St. Louis, the person has a possibility of gaining recovery of muscle function in the hand innervated by the ulnar nerve because the connection between the transferred anterior interosseous and the ulnar motor branch has such a short healing time. Long term follow up data is as yet lacking on the value of this procedure as promoted by Dr. McKinnon.

Resumption of Activity

A person may resume most of her normal activity within a few days of surgery with the exception of forceful pounding or throwing in the case of a transposition or epicondylectomy. No restriction is required for those undergoing an in- situ procedure. Pounding may not be well tolerated for a few weeks.