Nerve Entrapment Syndromes Treatment & Management
- Author: Amgad Saddik Hanna, MD; Chief Editor: Brian H Kopell, MD more...
Conservative measures should be tried first in most cases of entrapment neuropathy. Meralgia paresthetica secondary to pregnancy and obesity and intrapartum median nerve compression at the wrist may become completely asymptomatic after delivery or weight loss. Compression neuropathies secondary to systemic disease, such as thyroid disease and autoimmune conditions, may be effectively managed with treatment of the etiological factors.
In uncomplicated, nonsystemic cases, conservative management mainly consists of educating the patient to adopt avoidance behaviors. This seldom is practical in young, physically active patients, especially if symptoms are occupation-related. In cases of posterior interosseus nerve entrapment at the elbow caused by certain kinds of prosthetic devices (eg, Canadian crutches), redesigning or substituting the device may result in relief. Wrist splints for CTS are commonly prescribed but rarely provide long-term control.
Conditioning exercises and periodically injecting around the nerve with bupivacaine and dexamethasone may accord long-term relief. Surgery is recommended for patients with symptoms refractory to nonoperative measures and/or those with severe and long-standing symptoms or weakness.
The general principle of operative intervention is to decompress nerves in zones of compression. In some cases, surgical beds may be improved, or nerves can be transposed.
Carpal tunnel syndrome
Anesthesia may be local, regional, or general. The use of a tourniquet is optional. The surgical incision should be made directly over the palmaris longus tendon in line with the radial aspect of the ring finger, roughly coinciding with the longitudinal midpalmar crease. A 3 cm palmar incision may be used over the extent of the TCL. The distal extent of the incision can be approximated by the intersection of a line from the abducted thumb to the hook of the hamate and the flexed ring finger. The proximal extent of the TCL is the distal wrist crease. A small opening is made in the ulnar portion of the TCL and an elevator is passed beneath the ligament. The ligament is sharply incised ulnarly. The recurrent branch is not routinely visualized.
Fat surrounding the superficial palmar arch should be visualized at the distal extent of the decompression. Under direct visualization, a portion of the antebrachial fascia should be released proximally. Shorter or longer skin incisions can be used, each with potential advantages and disadvantages. A shorter incision may decrease postoperative pain but makes complete visualization more challenging. A longer incision crossing the wrist crease, allows identification of the median nerve beneath the antebrachial fascia before it passes under the ligament; however, healing of this portion of the incision may be slower.
Care should be taken not to injure cutaneous branches during the superficial exposure, the ulnar neurovascular bundle with the blade of the retractor, the median nerve itself and its recurrent and palmar cutaneous branches by staying ulnar during the carpal tunnel release, and the digital branches (and interconnections) during the distal part of the dissection.
The tourniquet, if used, is often released by surgeons prior to wound closure.
Endoscopic retinaculotome using either the 2-portal or single-portal technique has recently been advocated, with reports of more rapid recovery (including a faster return to work) and less postoperative pain are achievable compared with open surgery. The benefits are short lived and must be counted against a higher complication rate of injury to the ulnar and median nerves and to the superficial palmar (arterial) arch in some series.
Ulnar entrapment at the elbow
Five surgical procedures can be used to correct ulnar entrapment at the elbow, but, according to the literature, the specific indications for each are far from clear. In most instances, the surgeon's preference and expertise should influence the selection.[20, 21, 22, 23, 24]
In situ decompression
- An incision is made posterior to the medial humeral epicondyle overlying the ulnar nerve. Various techniques exist. In theory, the cubital tunnel is unroofed in the vicinity of the cubital tunnel retinaculum and the proximal portion of the flexor carpi ulnaris. This limited approach can be performed under local anesthesia via a short incision. The nerve is identified proximal to the medial epicondyle and decompressed distal to the medial epicondyle for several centimeters. The proximal potential anatomic sites of compression are not addressed. Some surgeons and authors, however, do decompress more proximally, addressing the medial intermuscular septum and arcade of Struthers. Still others perform circumferential neurolysis. More extensive proximal decompression and neurolysis makes the ulnar nerve more apt to dislocate with elbow flexion.
- The nerve is not circumferentially dissected out, which presumably avoids devascularization and damage to slender muscular branches to the flexor carpi ulnaris. This procedure works well with milder and less chronic forms of the disease. Many surgeons are performing this procedure due to recently published randomized studies demonstrating equal efficacy and decreased complications compared with other transposition techniques. In cases of spontaneous nerve subluxation or cases of excessive scarring or osteophytes formation within the cubital tunnel, the authors’ believe that the nerve should be anteriorly transposed.
Medial epicondylectomy: The nerve is first decompressed in situ. The medial epicondyle is subperiosteally exposed and removed without disturbing the common flexor origin of the pronator teres. Then, the soft tissues over the osteotomy bed are carefully approximated.
Anterior subcutaneous transposition, see the image belowCommon peroneal nerve decompression at the fibular neck. A: The common peroneal nerve (P) has been identified and mobilized proximal to the fibular tunnel region, fascia (F) covering peroneus longus. B: The common peroneal nerve has been traced through the fibular tunnel. The fascia overlying the peroneus longus muscle has been divided and the muscle (M) has been retracted. The fascial band overlying the nerve is released.See the list below:
- After neurolysis, the nerve is circumferentially dissected and mobilized from its cubital tunnel bed. Sensory fibers to the elbow joints are severed. Twigs that supply the upper fibers of the flexor carpi ulnaris should be preserved and carefully dissected away from the epineurium to gain length to allow the nerve to be moved onto the anterior surface of the elbow flexor muscles in front of the medial epicondyle.
- To avoid kinking the nerve at both ends of the transposition, a segment of the medial intermuscular septum is removed, and the aponeurosis and muscles fibers of the flexor carpi ulnaris are split longitudinally between the 2 heads. The nerve is then gently placed in a subcutaneous bed. A fasciodermal flap may be fashioned or several sutures may be placed between the skin flap and the surface of the pronator teres aponeurosis of the common flexor origin just in front of the medial epicondyle.
Intramuscular transposition: Adson originated this procedure, supposedly to lessen the vulnerability of the nerve in a subcutaneous location. After transposition, the nerve is placed in a shallow muscular trough created in the pronator teres and flexor carpi ulnaris.
- In 1942, Learmonth described this procedure of placing the nerve in an intermuscular plane lined by muscle fascia, where the nerve can glide with joint motions without being “stuck down,” as in the intramuscular or subcutaneous compartments.
- The pronator origin is divided often using a step-cut lengthening format, as is the origin of the flexor carpi ulnaris. The anteriorly transposed ulnar nerve is placed under the divided muscles on a fascial bed over the flexor digitorum superficialis and brachialis parallel to the median nerve. The cut ends of the divided tendons are reapproximated in the Z-plasty format so that they are lengthened, in effect to lessen the tightness over the underlying nerve bed.
- Gentle physical therapy is instituted to gradually return the joint to full extension over 3 weeks.
Ulnar nerve entrapment at the wrist
A longitudinal incision is made along the course of the ulnar nerve proximal to the wrist which curves across the wrist crease and then courses slightly toward the hook of the hamate. The ulnar nerve and vessels are mobilized proximally. The deep and superficial branches are protected and decompressed. The fibrotic arch over the deep branch is released.
Posterior interosseous nerve syndrome
The incision is made on the lateral side of the biceps muscle and is extended across the elbow and along the border of the brachioradialis. The radial nerve is picked up within the groove made by the biceps/brachialis and the forearm extensor group. This groove is held open by self-retaining retractors. The lateral antebrachial cutaneous nerve, if seen, should be protected. The radial nerve is then traced toward the upper border of the supinator. The bifurcation into the deep branch of the radial nerve and SRN are readily seen just above and in front of the radiocapitellar joint. The SRN courses deep to the brachioradialis and may be picked up first, in which case it is traced backward to locate the much deeper PIN.
Once the arcade is found, it is divided, together with fibers of the superficial supinator muscle, to expose the entire length of the PIN within the radial tunnel. The fascial thickening associated with the joint capsule also is divided, as is the arterial leash of Henry. The PIN can also be exposed through a posterolateral incision with forward reflection of the extensor muscles.
Suprascapular nerve entrapment
The patient is placed prone preferably in a Mayfield head holder. An incision is made 2 cm above and parallel to the scapular spine. The horizontal trapezial fibers are atraumatically split to expose the constant fat pad that separates the trapezius from the supraspinatus muscle. Digital palpation along the sharp, bony edge of the superior scapular border detects the abrupt change into rubbery springiness of the suprascapular ligament. Blunt dissection by firm, sweeping motion using a “peanut” dissector readily reveals the glistening, taut ligament. The suprascapular artery, which crosses above the ligament, is swept aside. The ligament is cut and the bony notch is enlarged with a Kerrison rongeur, if necessary. The nerve is exposed and decompressed. The operative microscope is often employed.
Surgical decompression, when necessary is very effective, but the recurrence rate is 15-20%. The skin incision is made along the medial border of the sartorius, 2 cm below the ASIS, and extends about 6-7 cm. The fascia over the sartorius is exposed. The fascia is then opened in one location and carefully extended. The nerve is located at the medial border of the muscle or just behind it. It may also be attached to the underside of the fascial sheath, so gentle handling is necessary to avoid accidentally cutting the nerve.
The nerve then is traced proximally toward its exit site just medial to the ASIS. The bands of the inguinal ligament over the nerve are divided. If a sharp ridge is palpable just below the nerve, it should also be divided to completely free the nerve of sharp surfaces. The nerve is then followed into the pelvis for a distance of 2-3 cm to ensure clearance of other iliacus fascial bands.
In spite of the incision on the inguinal ligament (on its lateral side), hernia is extremely rare after this procedure. Recurrence of symptoms can be treated with transection of the nerve. After freeing the nerve at the ASIS and proximally toward the pelvis, gentle downward traction is applied and the neurectomy is done proximally. This allows the proximal stump to retract proximally into deep tissues. This is thought to decrease painful neuroma formation on the surface of the thigh from occurring afterwards. Patients tend to adjust well to the numbness. Several studies also report excellent long-term control of symptoms with nerve transection as a primary treatment.
Various surgical procedures can be applied in the treatment of meralgia paresthetica, with the 2 main ones being neurolysis and neurectomy of the lateral femoral cutaneous nerve. In a study comparing the 2 procedures, pain relief was found to be more successful with neurectomy than with neurolysis. Neurolysis was performed in 8 patients and neurectomy in 14 patients. Successful pain reduction was 93.3% after neurectomy versus 37.5% after neurolysis.
Common peroneal nerve entrapment
Decompression could be performed under local anesthesia or with sedation.[29, 30, 31] An incision is made obliquely at the neck of fibula. The deep fascia is opened exposing the common peroneal nerve. The nerve is followed proximally along the biceps femoris tendon. Distally, the fascia over the peroneus longus is opened. The muscle is then retracted to expose the fascia deep to the muscle. The latter is divided to completely unroof the nerve and expose the terminal branches. The subcutaneous tissue and skin are then closed.[29, 30] See the image below.
Tarsal tunnel syndrome
The incision should begin 2 cm proximal to the medial malleolus to identify the neurovascular bundle. The nerve is then followed distally with release of the flexor retinaculum. Mass lesions or fibrous septa are identified and removed. Each of the plantar nerve canals is opened into the plantar surface. A tight fascial band that arises from the border of the abductor hallucis muscle and roofing over the plantar tunnels is divided. All intersecting septa are resected to convert the tunnels into a single cavity. The calcaneal branch is also decompressed. The ankle is placed in a soft splint and elevated for 3 days, with minimal weight-bearing allowed for an additional week.[12, 32]
Thoracic outlet syndrome
A supraclavicular approach to the brachial plexus is performed. Careful dissection of the brachial plexus roots and trunks is followed by exposure of the subclavian artery. Ample decompression of the artery and the lower trunk of the brachial plexus is achieved by resecting fibrous bands, scalenus anterior, cervical rib, or enlarged transverse process of C7. Decompression of C8 and T1 should be done to the level of their foramina. Some surgeons may also perform a transaxillary approach by itself or combined with a supraclavicular approach for scalenectomy, rib resection, and neurovascular decompression.
Most decompressions are performed safely in an outpatient setting. Surgical complications from anesthesia and coexisting medical conditions rarely occur. Damage to surrounding nerves or arteries from manipulation is also unusual.
Postoperative infections may develop, especially in those with diabetes mellitus and, unfortunately, predispose the patient to recurrence of entrapment
Outcome and Prognosis
In general, surgical outcomes are excellent in primary cases for improvement of pain and function. In secondary cases, results are fair to good; in these situations, pain relief is often the goal.
Carpal tunnel syndrome
Surgery is associated with a 70-90% rate of improvement of median nerve-related symptoms.
The most common potential complications include the following:
Incomplete sectioning of the TCL
Pillar pain along the thenar and hypothenar eminences (probably related to adjustment of the carpal bone alignments)
Temporary loss of grip strength secondary to relocation of the origin of the hypothenar and thenar muscles and bowing of the flexor tendons through the TCL incision
Most of these complications are transient. Neurovascular complications can rarely occur and have been reported with open and endoscopic techniques. Neural injury may affect the median and ulnar nerves, digital nerves (or communicating branches), cutaneous branches, and the recurrent motor branch and vascular injury, to the superficial palmar arch or ulnar artery.
Postoperative infection is reported in approximately 0-5% of patients. Palmar space infection is an extremely serious emergency that can result in permanent adhesive tenosynovitis and recurrent median nerve compression. Open drainage, use of a drain, and high-dose intravenous antibiotics should be instituted immediately.
Ulnar nerve compression at the elbow
Adherence to strict surgical principles results in a good outcome in approximately 80% of patients regardless of the procedure chosen. Surgical failure may be due to inadequate decompression or secondary compression of the ulnar nerve. One should also consider the possibility of a neuroma of the medial antebrachial cutaneous nerve in a patient with medial, volar forearm pain following previous ulnar nerve surgery. Revision ulnar nerve surgery most commonly employs a submuscular transposition, although this technique is by far the most complex and difficult to perfect.
Posterior interosseous nerve syndrome
Good to excellent outcomes are often achieved in these patients following spontaneous recovery or decompression.
Suprascapular nerve entrapment
Symptomatic improvement is frequently seen in patients who undergo decompression. Often this may be seen within days of the surgery, especially with respect to external rotation. However, long-term weakness and atrophy may take many months to improve, and some patients never regain full strength. Early detection is an important predictor of outcome in suprascapular entrapment.
Ulnar nerve compression at the wrist
Improvement is expected in the painful cases and in those with mild motor loss. In some cases, severe atrophy may improve due to the relative short distances for reinnervation from the site of compression to the muscle end-plate. Long-standing atrophy likely will not improve.
Surgical decompression is very effective, but the recurrence rate is 15-20%.
Tarsal tunnel syndrome
In general, 75% of patients enjoy significant improvement with surgical decompression of the tarsal tunnel. The best surgical results are observed in patients with mass lesions within the tunnel; the worst results are observed in patients who have undergone previous exploration for pain and those with plantar fasciitis and autoimmune diseases.
Future and Controversies
In the future, further advances will be made related to the diagnosis and management (ie, surgical outcomes) of common and uncommon entrapment neuropathies, not to mention certain pain syndromes (ie, radial tunnel, pronator and piriformis syndrome,[35, 36] pudendal nerve entrapment) and other types of neuropathies (eg, diabetes ) in which entrapment has been postulated to play a role. Hopefully, answers to these questions will allow new controversies to emerge.
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