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.
 


PROCEDURES

RADIAL NERVE ENTRAPMENT IN THE ARM

The radial nerve can be entrapped anywhere in the upper arm, forearm or wrist level. Radial tunnel syndrome is entrapment of the posterior interosseous nerve branch of the radial nerve that results mostly in pain rather than weakness. This is discussed elsewhere. The following discussion will center on the other sites of radial nerve entrapment.

Upper Arm
Anatomy

The radial nerve arises from the posterior cord of the brachial plexus. It receives contributions from C5 - C8 spinal roots. The nerve contains approximately 16,000 myelinated fibers.12 It runs medial to the axillary artery. At the level of the coracobrachialis it courses posteriorly to lie in the spiral groove of the humerus. In the lower arm it pierces the lateral intermuscular septum to run between the brachialis and brachioradialis. Opposite the head of the radius there are some fibrous bands from the joint’s capsule and immediately distal to this, the nerve is regularly crossed by several prominent veins, the “leash of Henry.” It divides 2 cm distal to the elbow into a superficial radial sensory branch (SRN) and a deep motor branch, the posterior interosseous nerve (PIN). It gives off branches to the, extensor carpi radialis longus and brevis, brachioradialis and anconeus before giving off the PIN branch. The PIN continues on between the superficial and deep head of the supinator muscle, to exit on the dorsal forearm. After it emerges from the distal border of the supinator, the PIN sends branches to the extensor digitorum communis, extensor carpi ulnaris, extensor digiti quinti, extensor pollicus longus and brevis and the extensor indicis proprius in descending order, although there may be considerable variation.

History
In the arm region, the radial nerve is often injured in association with some form of unconsciousness. In a Saturday night palsy, an obtunded patient sits with their arm over a chair back or rests his/her head on the lateral surface of their arm. Alternatively the radial nerve can be compressed in the groove between the brachialis and forearm muscles when one person rests their head on the middle third of the arm of another i.e. Honeymooner’s palsy.

Physical exam
The patient will typically present with a wrist drop and an inability to extend the fingers, thumb or wrist. In addition, the brachioradialis will be affected along with variable involvement of the triceps. They will also have diminished sensation over the dorsum of the 1st web space.

Electrodiagnostic studies
The NCS typically demonstrates the absence of the superficial radial SNAP. Motor recordings are more difficult since no muscle is sufficiently isolated from other radially innervated muscles. A surface electrode over the extensor indicus proprius (EIP) results in a volume conducted response from the adjacent radial innervated muscles, which makes side to side amplitude comparisons difficult. Radial nerve recordings using needle electrodes in the EIP are more common as a result, which makes it difficult to approximate the degree of axonal loss by assessing the amplitudes. The EMG however is quite useful, and permits a relatively accurate localization of the lesion. In a spiral groove lesion for example, all 3 heads of the triceps should be normal, with denervation of the brachioradialis and all muscles distal to it.

Quantitative sensory testing
The patients will have an abnormal 2PS and possibly 1PS over the dorsum of the first web.

Surgical Indications
For the majority of patients, nonoperative treatment is the mainstay. A failure to improve within 6 months combined with a nonadvancing tinels sign are indications for exploration.

Contraindications
The time for reinnervation must thus take the distance from the injury to the motor endplate into account. As a general rule, motor endplates degrade at about 1% per week, and the nerve regenerates about 1 inch per month. By 12 months the nerve will have grown approximately 12 inches and there will be a 50% loss of endplates, hence the maximum length that a nerve can grow to restore motor function is approximately 13 - 18 inches. For practical purposes, nerve decompression will be of no value with injuries that are more than 18 months old (> 75% loss of endplates) and alternative methods should be explored.

Surgical technique
A 6-8 cm incision is made over the posterolateral aspect of the midhumerus. The radial nerve is identified in the spiral groove and followed distally through the intermuscular septum. Any obvious areas of nerve constriction or loss of the normal striations (bands of Fontana) should undergo an epineurolysis. The use of intraoperative nerve stimulation will help differentiate a neuroma-in-continuity from nonviable nerve tissue. In the former case an internal neurolysis is justified v.s. excision and grafting.

Postoperative management
Immediate elbow mobilization is instituted following nerve decompression or neurolysis. Nerve grafting may require temporary elbow splinting for 4 weeks but it is preferable to insert a graft of sufficient length to allow early elbow extension.

Complications
The radial nerve is accompanied by the radial collateral artery in the spiral groove, which is at risk during decompression. Injury to the muscular branches may result in permanent denervation of one or more heads of the triceps. Injury to the posterior cutaneous nerve of the forearm may result in a tender scar and hypoesthesia.

Forearm
Entrapment of the posterior interosseous nerve (PIN) at the elbow can result in two separate clinical syndromes. Although the same nerve is compressed the clinical presentation may be different and merely represents two ends of the spectrum of PIN compression. The PIN is said to be a motor nerve, but it also contains sensory nerve branches from which the pain from radial tunnel compression is derived. The different clinical presentation may reflect the internal fascicular topography of the radial nerve. Pain symptoms predominate with nerve compression secondary to superficial structures and motor paralysis occurs from compression from below due to lesions arising from the radiocapitellar joint.

Pathophysiology
As it travels distally through the radial tunnel the PIN may potentially be entrapped by fibrous bands anterior to the radiocapitellar joint, the radial recurrent leash of vessels, the fibrous edge of the extensor carpi radialis brevis (ECRB), the proximal border of the supinator i.e. the arcade of Frohse or the distal edge of the supinator muscle.

Quantitative sensory testing
In both syndromes, sensory testing over the dorsum of the 1st web should be normal unless there is a superimposed C6 neuropathy.Posterior interosseous nerve entrapment

History
In posterior interosseous nerve syndrome the presenting symptoms are weakness and/or paralysis of the extensor muscles, which result in a wrist or finger drop. There may be a history of a fall onto an extended and pronated arm although many cases are spontaneous, especially if due to an underlying lipoma, ganglion or rheumatoid nodule arising from the radiocapitellar joint.

Physical
The patient will prevent with variable weakness or paralysis of the EPL, EIP, EDC and ECU. Motor function of the ECRB/L should be preserved since they are innervated before the PIN dives between the two heads of the supinator muscle. The patient will hence extend their wrist in radial deviation.

Electrodiagnostic studies
PIN lesions do not affect the superficial radial SNAP, which should be normal. The compound motor action potential of PIN innervated muscles may show a drop of conduction velocity or amplitude, but this is difficult to assess with surface electrodes. Needle EMG is the best technique for localization, especially with partial lesions. In acute denervation decreased recruitment, increased insertional activity and fibrillation potentials " positive sharp waves are present. In chronic lesions seen after 3-6 months, decreased recruitment may still be seen along with giant motor unit potentials and polyphasia due to peripheral axonal ingrowth.

Quantitative Sensory testing
This should be entirely normal in an isolated PIN palsy.

Nonoperative management
Unless preoperative imaging studies reveal a mass occupying lesion compressing the PIN, most are treated with observation and serial EMG studies. A wrist splint may be used for comfort.

Surgical Indications
MRI evidence of any type of mass compressing the PIN is an indication for exploration and decompression. In idiopathic cases, a failure to improve within 6 months without EMG evidence of reinnervation is an indication for exploration.

Contraindications
Diffuse denervation of the upper limb muscles or any other generalized neuromuscular disorder are contraindications to PIN decompression. A C7 radiculopathy, or extensor tendon ruptures especially in rheumatoid patients can mimic this disorder and should be ruled out. Surgical technique
This is identical to that of radial tunnel decompression.

Postoperative treatment
Elbow motion and PIN gliding exercises are instituted after an initial period of splinting for comfort.

Outcomes
Kline and coworkers reported their experience with 45 surgically treated posterior interosseous nerve (PIN) entrapments, tumors or injuries over a 27 year period. Most muscles innervated by the PIN achieved Grade 3 or better functional outcomes. They generally found that the PIN entrapment or injuries responded well to PIN release and/or repair. This is most likely due to the fact that the nerve does not have far to regenerate to reach the motor endplates.

Superficial radial nerve entrapment

Anatomy

The radial sensory nerve exits from under the brachioradialis approximately 5 cm proximal to the radial styloid and bifurcates into a major volar and a major dorsal branch at a mean distance of 4.2 cm proximal to the radial styloid. It then moves distally where it supplies sensation to the dorsum of the thumb, the 1st web space and the dorsoradial aspect of the carpus, extending up to the index and middle fingers.

Pathophysiology
The superficial radial nerve (SRN) can be injured in the distal forearm or at the wrist by tight bracelets or watch bands, handcuffs, radius fractures, lacerations, venous cutdown and blunt trauma. The SRN may also be entrapped as it exits the fascia between the tendons of the BR and ECRB.

History
Pertinent history may include compressive or crushing forearm injuries, work activities requiring frequent pronation and wrist hyperextension, and associated illnesses, such as diabetes. Symptoms included altered sensibility over the dorsoradial aspect of the hand and dorsoradial cutaneous pain with ulnar flexion of the wrist or with gripping and pinching.

Physical
Physical examination includes altered touch perception, moving 2 two-point discrimination > 15 mm, static two-point discrimination that is 5 mm greater than the contralateral 1st web space, a positive tinel’s sign over the SRN and aggravation of the patient's symptoms with forced forearm pronation and wrist ulnar flexion.74

Quantitative sensory testing
The patients will have an abnormal 2PS and possibly 1PS over the dorsum of the first web.

Electrodiagnostic studies
The distal radial sensory latency may be normal even in the presence of abnormal forearm conduction. This commonly occurs with nerve entrapment due to segmental conduction velocity slowing. In more advanced cases slowing or a complete block of the distal SRN occurs. If the response is absent, it is difficult to localize the lesion.

Surgical Indications
A failure to improve following conservative treatment with avoidance of repetitive wrist deviation and tight bands or jewelry is an appropriate reason.

Contraindications
DeQuervain’s tenosynovitis often includes a component of superficial radial nerve irritation and should be treated before considering SRN decompression.

Surgical technique
A 2 cm incision is made approximately proximal to the radial styloid. The superficial radial nerve is identified as it exits from underneath the tendon of the brachioradialis. The overlying fascia is split while care is taken not to disturb the nerve.

Outcomes
Dellon and MacKinnon reported on a group of 51 patients with complaints related to entrapment of the superficial sensory branch of the radial nerve. Seven (37%) of 19 patients treated with nonoperative modalities after a mean of 28 months from the onset of symptoms or their injury were improved. Of the 32 patients treated with surgery there was excellent subjective improvement in 37%, good subjective improvement in 49%, and fair subjective improvement in 6%, and 8% were not improved.74

Complications
The complications for each procedure are similar. They include wound problems related to infection, skin healing, tender scars due to injured cutaneous nerves, hematoma and iatrogenic injury due to rough nerve handling and/or retraction. These can be minimized by meticulous hemostasis, gentle nerve handling and precise surgical technique. Stiffness can occur and is minimized by early joint mobilization. The incidence of residual symptoms are predicated by the preoperative degree of nerve injury.

Conclusions
From the above discussion it is apparent that compressive neuropathies share similar features. Although each focal neuropathy has been discussed in isolation, multiple compressive neuropathies often co-exist. The element that is common to all focal neuropathies is nerve ischemia which leads to the sensory and/or motor abnormalities in the distribution of the specific nerve that is affected. Provocative tests exploit this feature by seeking to dynamically increase the ischemia through external pressure and/or traction in order to precipitate symptoms. Although ancillary testing can yield useful information, most hand surgeons intuitively understand that the indication for surgery still hinges on reproducible physical findings combined with the appropriate clinical symptoms rather than on a test abnormality.