David J. Slutsky

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3475 Torrance Blvd., Ste F
Torrance, CA 90503

Appointments: 310.792.1809
Fax: 310.792.1811

Office hours: M-F, 9am – 5 pm

Worker’s compensation, Medicare and most insurance plans accepted.

In September 2008, we will be moving to a beautiful new 4,400 sq ft, state of the art dedicated hand center located at 2808 Columbia Ave in Torrance, CA., which will feature onsite nerve conduction studies, occupational hand therapy and digital x-ray.



Similar to carpal tunnel syndrome (CTS), this condition is the name given to a peripheral nerve entrapment. The nerve involved however is the ulnar nerve, as it passes through a natural tunnel behind the elbow. The ulnar nerve is responsible for the sensation to the small and ring fingers, as compared to the median nerve which supplies the thumb, index and middle fingers. The ulnar nerve supplies all of the small intrinsic hand muscles which are responsible for approximately 50% of the grip strength. This region of the ulnar nerve has been commonly referred to as the “funny bone”, since a blow to this nerve behind the elbow results in an electric shock like sensation radiating to the small and ring fingers. When the nerve is compressed, this occurs much more readily with only minor stimulation of the nerve.

Applied Anatomy:
The ulnar nerve (C8-T1) arises from medial cord of the brachial plexus and passes through the medial intermuscular septum where it enters the upper inner aspect of the arm. It is then crossed by thick layer of tissue called “fascia” which runs from this septum to the triceps muscle 8 cm above the elbow (antebrachial fascia). It then lies on top of a groove behind the bone prominence on the inside of the elbow (“the medial epicondyle”) where it is crossed over by fibrous bands (Osborne’s ligament) which form a roof over the groove. The ulnar nerve then dives between the two heads of the flexor carpi ulnaris (FCU) which is the large muscle on the inside of the upper forearm. The aponeurosis or bands of fascia uniting the heads of the FCU is a common site of ulnar nerve entrapment. During a nerve decompression all 5 of these sites must be released to prevent secondary nerve impingement, which will lead to a persistence of symptoms.

Microscopic anatomy:
The ulnar nerve at the elbow level is composed of 1 large nerve bundle or fascicle and 2-3 small fascicles. The motor fibers to the flexor carpi ulnaris, the intrinsic hand muscles and the deep flexors of the small and ring finger lie deep within the nerve, while the sensory fibers are superficial. Since the site of compression often starts on the superficial surface of the nerve, sensory symptoms occur earlier and more commonly i.e. numbness and tingling of the fingers, versus muscle weakness.

The ulnar nerve glides 6-10 mm and elongates up to 5 mm when the elbow goes from full extension to full flexion. The condylar groove is round, spacious in extension and becomes a flattened triangle during flexion (narrowed by 55%). The pressure within the nerve normally increase 2X with wrist extension, elbow flexion and shoulder elevation in the normal situation, but 6 fold if the nerve is tethered.

Nerves normally glide as much as 5-8 cm with elbow flexion and extension. This allows the nerve to adapt to the difference in length with joint motion, without compromising the nerve circulation. When there is inflammation, the nerve becomes tethered. This is akin to placing your finger on the fret of a guitar string. The shortened segment of the guitar string vibrates at a higher frequency when plucked. In a similar fashion, if the ulnar nerve is tethered at the elbow, the remaining shorter sections of the nerve before and after the site of nerve tethering must overstretch to accommodate the changes in length between full elbow flexion and full extension. As a consequence, the blood supply to the nerve is strangled, which leads to the symptoms of finger tingling and numbness.

An ulnar nerve injury at the elbow that is due to mechanical compression, or nerve traction due to scarring hence leads to microstretching of the fixed nerve. Continued trauma results in fixed scar (compression). This leads to impairment of the normal intraneural circulation which leads to a “pins and needles” sensation (paresthesiae), of the small and ring fingers. Initially the compression causes intermittent swelling within the nerve substance, which in turn causes intermittent symptoms. With continued pressure, the nerve loses it’s outer insulating cover (myelin) similar to longstanding carpal tunnel compression. This local demyelination leads to a loss of sensation in the fingers, as well as muscle weakness and wasting. If unrelieved the nerve fiber degeneration causes permanent muscle wasting and a loss of finger sensation, that does not reverse following surgery.

Some of the inciting events that lead to ulnar nerve compression include activities that involve repetitive elbow flexion/extension such as assembly line work or in throwing athletes. A common precipitating event is talking on a cell phone since the elbow is flexed for long periods of time while the user holds the phone to their ear. Other causes include direct trauma to the ulnar nerve, elbow fractures and postoperative palsy from nerve traction or compression due to limb positioning on the operating table. The majority of cases however are of an unknown cause or idiopathic.

Clinical Symptoms/Signs:
In mild cases the patient complains of intermittent paresthesiae or tingling of the small and ring fingers, subjective hand weakness and clumsiness. In more advanced cases the paresthesias become persistent and the patient develops muscle atrophy. The diagnosis is based on the appropriate symptoms as well as a positive elbow flexion test. This is a provocative test that places the ulnar nerve on maximal stretch by flexing the elbow and extending the wrist. The reproduction of numbness or tingling in the small and ring fingers after 1 minute is considered positive. Many patients with carpal tunnel syndrome will also have signs of cubital tunnel syndrome, since both syndromes are precipitated by similar activities. A nerve conduction study is often useful in grading the degree of nerve entrapment. Most patients however, will have normal nerve conduction studies unless the nerve compression is longstanding or very advanced.

Conservative Treatment :
Unless there is a sensory and motor loss the initial treatment is always conservative. This consists mostly of activity modification which focuses on maintaining the elbow in a more extended position during activities such as typing or writing. Patients are counseled in avoidance of resting their head on their hands which leads to direct nerve compression through leaning on a flexed elbow, resting their forearms on the car window or prolonged elbow flexion while holding a telephone handset to their ear. The use of an elbow extension splint at night is encouraged to avoid the nocturnal symptoms arising from sleeping with a flexed elbow, in addition to taking NSAIDs. Unlike carpal tunnel syndrome, cortisone injections are of a limited value, but most patients can safely be treated conservatively for a longer period of time.

Surgical Treatment
If there is no response to these conservative measures after a reasonable length of time (2-3 months) surgical decompression may be considered. There are a number of different techniques for decompressing the nerve, ranging from releasing the cubital tunnel and leaving the nerve in place (in situ release), to transposing the nerve in front of the elbow underneath the skin (subcutaneous transposition) to burying it within (intramuscular) or underneath the forearm flexor muscles (submuscular transposition).

The most common procedure consists of a subcutaneous anterior nerve transposition, which involves moving the nerve anterior to the elbow and leaving it just underneath the subcutaneous tissue (link to ulnar nerve transposition video). This accomplishes two things. By moving the nerve in front of the axis of elbow rotation, the nerve is now relaxed rather than stretched with elbow flexion. In addition, the nerve is moved from a fibrotic compressing bed, to a healthy uninflammed area. I favor the use of a mini-incision approach since patients have a more cosmetic scar and less postoperative pain than with the standard 10-12 cm incision. The procedure is performed by making a 2-3 cm incision just below the medial epicondyle, which is the bony prominence on the inside of the elbow. The tough fibrous bands over the ulnar nerve in the epicondylar groove are released link to cubital tunnel figures 1- 2). The nerve is also decompressed below the epicondyle for an additional 5 – 7 cm as it passes in to the forearm between the two heads of the flexor carpi ulnaris muscle and 8 cm above the epicondyle by dividing the deep brachial fascia in the upper arm by retracting the skin and using and endoscopic assist (link to Endoscopic ulnar nerve video). Next a 1x 1 cm flap of the tough covering over the common flexor muscle origin or fascia is raised and placed underneath the transposed ulnar nerve link to cubital tunnel figures 3 -5). This prevents the nerve from falling back in to the groove or snapping back and forth over the medial epicondyle, during elbow flexion and extension. The end result is a very small and cosmetic scar (link to cubital tunnel figures 6- 8). During an ulnar nerve decompression special attention is pain to 4 separate sites which must be release to adequately decompress the nerve and to prevent secondary impingement once it is transposed. This includes the deep brachial fascia, the medial intermuscular septum, the epicondylar groove and the fibrous aponeurosis between the two heads of the flexor carpi ulnaris muscle. Care is take to the include the blood vessels that run with the ulnar nerve i.e. the superior ulnar collateral artery, to preserve as much of the ulnar nerve blood supply as possible.

Depending upon the length of compression, the patient may experience immediate relief of the symptoms v.s. gradual improvement over time. Unlike the median nerve at the wrist, the ulnar nerve normally has a large proportion of fibrous tissue to nerve tissue at the elbow. This results in more intraneural scarring, and hence it is more common to have residual symptoms following a cubital tunnel release as compared to a carpal tunnel release.

Because of the large forces acting across the elbow a submuscular transposition is the procedure of choice for throwing athletes such as baseball pitchers. In other instances, I prefer to reserve this more extensive release for cases of recurrent symptoms following a prior subcutaneous release or those with a subluxing ulnar nerve where the nerve snaps back and forth across the medial elbow condyle with elbow flexion. A submuscular transposition may also be considered in very thin individuals with little subcutaneous tissue since the nerve may not have adequate soft tissue padding following a subcutaneous transposition and may remain quite sensitive. A submuscular approach requires a release of the common origin of the forearm flexor muscles from the medial epicondyle (link to streaming ulnar nerve submuscular video). The ulnar nerve is then placed deep to these muscles, which are lengthened and repaired ( link to cubital tunnel figures 9 – 11). With judicious skin retraction this more extensive procedure can also be performed through a relatively small incision. The elbow is initially immobilized in 90 degrees of flexion to protect this repair, followed by progressive elbow extension exercise over a 4-6 week period. Nerve gliding exercises are instituted immediately to prevent nerve tethering in its new location.

The results of an ulnar nerve release are not as predictable as those following a carpal tunnel release. Even patients with normal nerve conduction studies however can achieve good results with resolution of the paresthesia or tingling and increased strength. Patients with motor weakness and sensory loss fare less well although clinical improvement can continue for up to 1 year following surgery due to remyelination or “rebuilding” of the insulating layer of the nerve.

Work Considerations
Most people can perform one-handed work activity by the 2nd week followed by light duty including clerical work at 6-8 weeks. Heavy manual labor can often be resumed by 8 -12 weeks.