Clinical Presentation

Carpal tunnel syndrome (CTS) is caused by chronic compression of the median nerve within the carpal tunnel. ¹ Carpal tunnel is built by carpal bones (scaphoid, trapezium, hamate) and is covered by the flexor retinaculum. Tendons of the flexor pollicis longus, flexor digitorum superficialis and profundus, and the median nerve pass through it. CTS is the most common upper limb nerve entrapment neuropathy. The estimated prevalence of CTS is 6%. ² CTS is much more common in women than men (3–4:1). In gravidity, obesity, and renal dialysis, the incidence is higher than in normal population. Symptoms vary from numbness in the thumb, index, middle, and/or radial half of the ring fingers to pain in the forearm, wrist, and palmar hand. The numbness may be intermittent or absent in an early stage, and, with time, symptoms increase. Usually, numbness occurs more frequently during sleep (nocturnal paresthesia) ^{3,​ 4} and disappeared by hand activity. Shaking the hand or rubbing it alleviates the symptoms. In later stages, burning pain occurs in the palmar hand, wrist, and forearm and is a major complain. If CTS is burned out, the patient develops thenar atrophy, weakness of thumb opposition, and persistent numbness with loss of texture discrimination and fine motor skills. ⁵ In neurologic examination, Tinel’s sign (tingling is reproduced by tapping the anterior aspect of the wrist with your fingers) may be positive above the carpal canal. Phalen’s test (wrist flexion test) may be also present. Both tests are less sensitive than the electrodiagnosis. ^{3,​ 6} In most cases, physical examination is specific. To confirm the diagnosis, electrophysiological evaluation is essential. ⁷ In early stages, sensory nerve conduction studies are more sensitive than motor conduction studies. ⁸ Electromyograms (EMGs) are usually not needed. ⁹ Ultrasound imaging is of value in the diagnosis of recurrent CTS ¹⁰ or to exclude a tumor. Magnetic resonance imaging (MRI) is more expensive and not generally available. It is indicated in special situations.

Timing

Treatment options range from nonsurgical approaches, including activity modification, nonsteroidal anti-inflammatory medication, splinting (full-time vs. nocturnal), and corticosteroid injections, to surgical decompression of the carpal tunnel using a variety of methods.

Conservative management is used for patients with mild symptoms in the absence of neurological deficits. In case of nocturnal paresthesia, volar wrist splints can temporary relieve the symptoms. Steroid injection into the carpal canal can alleviate symptoms; however, it is generally felt to be a temporary treatment.

The following circumstances indicate surgical intervention in a timely manner:

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  Failure of nonsurgical therapy after a period of 8 weeks to relieve pain and/or progressive motor or sensory deficits. ¹¹

  
  
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  Neurological deficits such as permanent numbness, weakness, loss of texture discrimination, and fine motor skills.

  
  
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  Absolute indications for carpal tunnel release include rapidly progressive or acute course.

One year after surgical treatment, patients’ complaints are relieved in almost all cases (90–95%). ¹² The results correlate with the degree of preoperative deficits and the duration of symptoms. The recurrent rate is low (0.5–2.2%). ^{12,​ 13}

Surgical Strategy

Surgical carpal tunnel release can be performed under general, regional, or local anesthesia on outpatient basis. Generally, we perform the procedure under local anesthesia on outpatient basis. Exceptional cases are patients under antiplatelet therapy, tumor as a cause of CTS, and recurrent CTS. Open carpal tunnel release is the current gold standard treatment. Endoscopic technique has been developed and in use for over 20 years. Release of the transverse carpal ligament is the aim of both techniques.

Open Carpal Tunnel Release

After subcutaneous infiltration with a local anesthetic, a blood pressure cuff is applied to achieve ischemia. Incision is made in the proximal palm between the thenar and hypothenar creases with a total length of 3 to 4 cm ( ▶ Fig. 13.1). Fatty tissue is removed to exhibit the palmar fascia. At this stage of the surgery, you have to take care of the terminal branches of the palmar cutaneous nerves. The palmar fascia is divided sharply and the transverse carpal ligament is shown distally to the rascetta. Afterward, the entire ligament is divided under direct vision. Additional motor branch decompression is usually not needed. Further manipulation, particularly, internal neurolysis, may result in scar formation and has risk of fascicle damage. No difference in results was reported either after internal neurolysis or after epineurotomy. ¹⁴ Reapproximation of the sectioned carpal ligament is not recommended. The skin is closed in a simple fashion. At the end of the surgery, the wrist should be bandaged. Splinting is not necessary.

A variation of this open technique is called “limited open technique” or “mini-incision.” In this case, the transverse carpal ligament is divided through a shortened skin incision of about 1.5 to 2 cm. This technique allows limited inspection of the carpal tunnel and may lead to incomplete release of the ligament and iatrogenic nerve lesion by unexperienced surgeons.

Endoscopic Carpal Tunnel Release

There are two systems used for endoscopic carpal tunnel release: the Agee single portal technique ¹⁵ and the Chow dual portal system. ¹⁶ In comparison to the open technique, results do not differ relating to side effects, complications, and recovery time. ¹⁷ Contraindications are prior surgery on the palmar hand, tumor, arthritis, or wrist articulation rigidity.

Single-Portal Technique Described by Agee ¹⁵

The requirements of this technique are the same as for the open technique (decompression performed under local anesthesia, ambulatory care). A tourniquet control is obligatory. Skin incision is made at the ulnar side of the tendon of the palmaris longus with a total length of 1 cm ( ▶ Fig. 13.2). The palmar fascia is divided and the transverse carpal ligament is visualized through an endoscope, which looks like a pistol ( ▶ Fig. 13.3). A specially designed blade through the open roof of the trocar is used to transect the ligament from the distal to the proximal end ( ▶ Fig. 13.4). Visibility may be reduced by fatty tissue.

Two-Portal Technique Described by Chow ^{16,​ 18,​ 19}

Release of the transverse carpal ligament is performed under tourniquet control and local anesthesia. Two skin incisions are needed. The first incision is made like the single-portal technique and the second in the palmar hand ( ▶ Fig. 13.2). The endoscope is inserted from both sides after positioning a slotted cannula from the opposite skin incision ( ▶ Fig. 13.5). Retrograde blade cuts the whole length of the ligament until fatty tissue protrudes.

Complications

Complications from surgical treatment of CTS must be attributed mainly to poor technique. Complication rate for the endoscopic technique is around 5.6%, meanwhile it is 2.8% for open release. ²⁰ The most common cause of failure of carpal tunnel release is incomplete sectioning of the transverse carpal ligament. Damage of motor and sensory branches is rare; however, it can cause severe disability of hand function. The phenomenon of so-called pillar pain is controversial. Patients complain of pain in the palmar hand after surgical treatment. Symptoms usually relieve after 4 to 6 months spontaneously. Complex regional pain syndrome (CRPS I) after surgical treatment is rare. Symptoms are edema, pain, circulatory disturbance, skin changes, and finally functional limitation of hand movement. Rosenbaum and Ochoa described CRPS I in 10 cases out of 7,000 surgeries. ²¹

13.1.2 Median Nerve Entrapment at the Elbow

Anterior Interosseous Nerve Syndrome (Kiloh–Nevin Syndrome)

Clinical Presentation

The anterior interosseous nerve is a motor branch of the median nerve and arises 4 to 8 cm distally to the elbow. It penetrates the anterior interosseous membrane as the last major branch of the median nerve and innervates the pronator quadratus and flexor digitorum profundus to the index and long digits.

Typically, patients have a history of acute pain in the elbow and forearm for a few hours, which terminates spontaneously. Corresponding to the nerves distribution, a nerve lesion leads to inability to flex the distal phalanges of the thumb and index finger and/or paralysis of the distal interphalangeal joints of the long finger. Therefore, the patient is unable to form an “O” with their tips of the thumb and index finger (pinch sign) ( ▶ Fig. 13.6). In addition, weakness of the pronator quadratus occurs. Sensory complaints are missing.

Besides a tendon rupture, further differential diagnosis is a Parsonage–Turner syndrome (plexus neuritis). Cases of nerve rotation located within the median nerve trunk or anterior interosseous nerve were described.

Electrophysiological testing is of value. Electromyography shows denervation in the muscles supplied by the anterior interosseous nerve. Sensory nerve conduction studies are normal, because this nerve has no primary sensory component. In all these cases, MR neurography of the upper arm and brachial plexus region is recommended.

Timing

Decompression of the nerve should be done if conservative treatment has not been successful after 12 weeks ^{22,​ 23,​ 24} and other causes for this pathology are excluded. Seror concluded that surgery should not be considered for a year, as late spontaneous recovery can occur. ²⁵ There have also been reports that suggest no difference in outcome between surgical and conservative treatment. ^{26,​ 27}

Surgical Strategy

Surgery can be performed under general anesthesia and tourniquet control. The skin incision is S-shaped along the radial border of the pronator muscle ( ▶ Fig. 13.7). Branches of the lateral and medial antebrachial cutaneous nerves must be protected. The lacertus fibrosus should be divided along the median border of the biceps tendon. Struthers’ ligament, if present, should be cut through. The nerve and its branches should be exposed in its course more distally until the flexor superficial arch. Constrictive tissue like fibrous bands should be removed when encountered.

Pronator Teres Syndrome

Clinical Presentation

Symptoms can be similar to the CTS. Nocturnal paresthesia is usually missing. Patients describe pain in the area of the elbow and proximal forearm aggravated by using the arm (especially in activities where the forearm is subjected to permanent pronation and supination). Sensory complaints are inconsistent. Weakness may occur especially if the anterior interosseous nerve is involved. Tenderness on palpation over the median nerve in the proximal forearm can be observed. Spinner described provocative tests to establish the level of compression: in flexion and supination of the forearm against resistance, the pain can be triggered if the compression level occurs at the level of lacertus fibrosus or the Struthers arcade. If pain aggravates while extending the pronated forearm against resistance, the entrapment could occur beneath the pronator teres; and resisted middle finger sublimis flexion suggests compression at the sublimis arch if these resisted movements trigger pain in the proximal forearm. ²⁸ Electrophysiological testing may show denervation of the median nerves’ supplied muscles. High-resolution ultrasound can be of value.

There are doubts of the real existence of the interosseous anterior and the pronator teres syndrome.

Timing

Treatment depends on the severity of the symptoms. Avoiding triggering movements and the use of anti-inflammatory medication and splints at the elbow or wrist may be helpful. Surgical treatment is an option if symptoms persist longer than 6 to 8 weeks.

Surgical Strategy

The surgical approach is a gentle S-shaped incision in both entrapment syndromes ( ▶ Fig. 13.7). The antebrachial cutaneous nerve should be treated with care. The median nerve is easily found medial to the tendon of the biceps. The lacertus fibrosus is excised. A possible supracondylar process of the humerus and/or a Struthers ligament should be resected. A high origin of the superficial head of the pronator teres could be responsible for compressing the nerve: in this case, it must be divided. Branches that arise from the medial aspect of the nerve and go into the muscle must be preserved. The next possible compression point is the deep head of the pronator teres on the lateral side of the median nerve, which build together with the superficial head a fibrous arch. After resecting this arch, dissection continues along the course of the median nerve. A more distal compression can also occur at an accessory long head of the flexor pollicis longus muscle (Gantzer’s muscle), which must be resected. After releasing all potentially structures, the nerve itself is observed. Pseudoneuromas, increased vascularization, and fibrotic areas may be detected at the compressions side.

13.2 Ulnar Nerve

13.2.1 Ulnar Nerve Entrapment at the Elbow

Clinical Presentation

The so-called cubital tunnel is a fibro-osseous tunnel whose extension is about 10 cm. It begins approximately 6 cm proximal to the elbow where the ulnar nerve transverses the intermuscular septum from anterior to posterior. Struthers described a ligament between the medial triceps head and the medial intermuscular septum (“Struthers’ arcade”) ^{29,​ 30} as a potential compressive point. Dellon could not verify the existence of this arcade in his explorations. ³¹ As it approaches the elbow, the ulnar nerve is located between the medial epicondyle of the humerus and the olecranon, being bridged by an aponeurosis called Osborne’s ligament (or ligamentum arcuatum). ³² In 11% of all cases, a residual anconeus epitrochlearis muscle is identified instead of the Osborne ligament. ³³ The ulnar nerve transverses the two heads of the flexor carpi ulnaris underneath the deep fascia (submuscular membranes) 5 cm distally. This fascia contains fibrovascular bands, which may also compress the ulnar nerve at this point at the end of the tunnel. A further reason for ulnar nerve entrapment is chronic subluxation or luxation of the ulnar nerve. Cubitus valgus deformity after a humeral fracture may be a cause years prior to the onset of symptoms (tardy ulnar nerve palsy). Rare reasons are tumors or a ganglion cyst (see ▶ Fig. 13.9).

Ulnar nerve entrapment at the elbow is the second most common entrapment syndrome. ³⁴

Intermittent hypesthesia in the ulnar nerve distribution is the most common initial symptom. Furthermore, patients report of pain in the region of the elbow and forearm as well as shooting pain in the hand and digits. Loss of fine motor skills, such as writing and turning around a key, intrinsic muscle atrophy, and weakness occur on later stages.

Positive Froment’s sign ³⁵ is a characteristic sign of ulnar nerve deficit. The patient is asked to take a piece of paper between the thumb and the index finger. The examiner tries to move away the piece of paper. Because of the weakness of the adductor pollicis, flexor pollicis brevis, and first dorsal interosseous muscles, the patient is not able to hold the paper, compensating by flexing the flexor pollicis longus of the thumb to maintain grip pressure. The elbow flexion test ³⁶ is another clinical test for ulnar nerve dysfunction. Hypesthesia and tingling occur as a result of direct compression over the ulnar nerve at the elbow. In many cases, Tinel’s sign is positive as well.

Electrophysiological testing is useful for diagnosis. Motor nerve conduction velocity is decreased in the elbow region (<50 m/s). In comparison to the forearm region, motor nerve conduction velocity is reduced to about 10 m/s. Furthermore, there may be a significant amplitude reduction of the motor response potential after stimulation proximally—but not distally—at the cubital tunnel of about 20%.

If there is a history of trauma, X-ray of the elbow is helpful. Ultrasound of the ulnar nerve may show pseudoneuromas, tumors and ganglion cysts, scar tissue compressing the nerve, and potential transposition of the nerve in motion. In comparison to ultrasound, MRI is more specific, but also more expensive.

C8 radiculopathy, Guyon’s syndrome, thoracic outlet syndrome, and plexus brachialis lesions are potential differential diagnoses.

Timing

The treatment decision is based on the degree and severity of symptoms, as in other entrapment syndromes. For patients with mild and/or intermittent symptoms, treatment is nonsurgical, including avoidance of repetitive movements (flexion and extension). Splinting has no advantage. ³⁷ If development of atrophy or weakness is detected, primary surgical treatment is indicated without delay.

Surgical Strategies

There are various surgical techniques:

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  Simple in situ decompression (open and endoscopic).

  
  
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  Subcutaneous transposition.

  
  
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  Submuscular transposition.

  
  
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  Medial epicondylectomy.

  
  
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  Intramuscular transposition.

The last technique is not in use anymore, at least in our department.

Simple In Situ Decompression

Decompression is performed under local anesthesia on an in- or outpatient basis. Tourniquet control can be used. The incision is made slightly anterior to the medial condyle with a total length of 3 to 4 cm ( ▶ Fig. 13.8). The posterior branches of the medial cutaneous nerve of the forearm often have variable courses, so they have to be protected when using this approach. The ulnar nerve is identified proximally to the sulcus and dissected 5 cm distally toward the condyle. To achieve this, the Osborne ligament is divided. If the arcade of Struthers is found, it is also released. The ulnar nerve should be explored between the two heads of the flexor carpi ulnaris muscle and the submuscular membranes, and other constrictive tissue around the nerve are released. Pseudoneuromas may be present proximally to the compression. Splinting is not necessary after surgery. Endoscopic decompression of the ulnar nerve was first described by Tsai in 1995. ³⁸ For this approach, the incision is up to 2 cm in length, which is used as a port for the endoscope. Long-distance decompression is possible for a length of up to 12 cm from the retrocondylar groove and 6 to 8 cm proximally of the sulcus ( ▶ Fig. 13.9, ▶ Fig. 13.10).

Related posts:

Clinical Aspects of Traumatic Peripheral Nerve Lesions in the Lower Limb Surgical Repair of Nerve Lesions: Neurolysis and Neurorrhaphy with Grafts or Tubes Nerve Injuries: Anatomy, Pathophysiology, and Classification Compressive Lesions of the Lower Limb and Trunk Ultrasound in Peripheral Nerve Surgery Nerve Anatomy of the Upper Limbs

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