The onset of CTS can be classified into two categories: (1) acute and (2) chronic. Acute CTS is associated with a traumatic event, such as blunt trauma to the wrist, wrist fracture, infections, vascular disorders, rheumatologic disorders, hemorrhagic problems, burns, and high pressure injection injuries.1 These traumas produce a sudden and sustained increase in interstitial pressure within the carpal tunnel, resulting in a median nerve conduction block from intracompartmental and intraneural ischemia. This form of CTS is a medical emergency and requires immediate carpal tunnel decompression.

Chronic CTS is the result of an insidious rise of the interstitial pressure in the carpal tunnel and is classified as early, intermediate, or advanced. Patients with early CTS experience mild, intermittent symptoms that have been present less than 1 year. Intermediate CTS is characterized by more constant symptoms, including numbness and paresthesia, usually worse at night, with little or no atrophy of the thenar muscles. Surgery performed at this time uncovers a nerve that has undergone chronic changes, including epineural and intrafascicular edema. If decompression is performed at this time, then the neural changes are frequently reversible, although night symptoms may take a year to resolve. Advanced CTS is characterized by progressive paresthesia, atrophy of the thenar muscles, and pinch and grip weakness. Even after a successful surgical decompression, the chronic changes in the median nerve may be permanent.⁹

CTS can affect anyone, although females tend to have a higher incidence. Medical and ergonomic histories have been identified as independent risk factors in developing CTS, although controversy exists as to the contribution of work activities to the development of CTS.^10–12 Recent studies have looked at obesity as defined by body mass index; other biologic factors, such as genetics or structural make-up; and wrist anthropometrics as possible contributing factors.^13–18 There are some strong associations between CTS and age, gender, and female hormonal status as seen, for instance, during menopause or pregnancy.¹² Pregnancy can precipitate CTS by causing edema around the structures traversing the carpal canal. During pregnancy the symptoms of CTS tend to occur in the last trimester, secondary to fluid retention. The condition usually resolves within 6 to 12 weeks after delivery.⁹

CTS can also be associated with a number of other disease processes, including thyroid disease, rheumatoid arthritis, and diabetes, as well as with various anatomic anomalies such as a persistent median artery, median nerve variations, extramuscle bellies, and extratendinous slips.^15,18–20 Tumors and ganglions of the wrist, although rare, can precipitate CTS as the lesion occupies space within the carpal canal.²¹ Wrist trauma can cause CTS because of the resulting edema and hematoma surrounding the median nerve. Variations in lumbrical origin, length, or width can increase carpal tunnel pressure as dynamic lumbrical incursion into the CT can occur during finger flexion movements.²²

From the ergonomic side, CTS is often seen in patients who perform repetitive activities in their work or hobbies. One study of computer workers demonstrated that the angle of wrist extension (more than 20°) was associated with developing CTS.²³

The diagnosis of CTS can usually be made based on a thorough history and careful physical examination. In cases in which the diagnosis is uncertain, electrodiagnostic studies can be helpful in either confirming or ruling out the disorder.²⁴

In general, patients who are diagnosed with early stage CTS are initially treated without surgery. Nonsteroidal antiinflammatory drugs, although often prescribed, have not been shown to be effective in any controlled study to date^25,26 In some patients with recently developed CTS (less than 1 year), local injection of steroid medication into the carpal canal or oral steroids can significantly, although temporarily, reduce the symptoms of median nerve compression (Fig. 12-1). It has not been shown that a steroid injection can actually alter the progression of the disorder.^5,27

The best evidence-based conservative physical therapy treatments for CTS include splinting, deep pulsed ultrasound (US), nerve-gliding exercises, carpal bone mobilization, and yoga.^26,28 Splinting the patient’s wrist can be very helpful in controlling nighttime pain symptoms.²⁹ The wrist is splinted in a neutral position that maximizes the carpal tunnel space³⁰ and minimizes the carpal tunnel pressure.³¹ The splint is chosen based on the patient’s needs and comfort. The metal stay of a prefabricated wrist splint is easily replaced with a custom-molded thermoplastic stay to position the wrist in neutral. A positive Berger test (the patient holds a full fist position for 30 to 40 seconds, with a positive test reproducing paresthesia) result would suggest that the metacarpal phalangeal joints should also be immobilized in the splint, as the lumbricals can descend into the carpal tunnel with active finger flexion and cause further space compromise of the carpal tunnel contents.^10,32 All patients should sleep in their splints. Patients who have constant or activity-induced paresthesia may also wear their splints during the day.³⁰ When such conservative measures fail to resolve symptoms, surgery is indicated.

Classic CTS symptoms include the following⁵:

Sensory changes are commonly the first symptoms noted. The patient typically reports paresthesia and numbness of the digits served by the sensory branches of the median nerve and in the tips of the thumb, index finger, middle finger, and radial half of the ring finger, although both sides of the ring finger can be affected. Sensory symptoms may also be restricted to a single digit, or even involve the entire hand.¹ Sensibility in the thenar eminence is usually unaffected as this area is innervated by the palmar cutaneous branch of the median nerve, which branches proximal to the carpal tunnel, entering the hand volar to the TCL.

The onset of pain is most often the primary reason a person with chronic CTS seeks medical attention. The pain associated with CTS tends to begin in the latter aspects of the early and then into the intermediate stages. The patient complains of an intermittent, vague, dull aching in the wrist or forearm. Less common is pain radiating to the elbow and even the shoulder. Night pain is a common complaint most likely caused by congestion of the venous system during sleep.³³ Neurologic muscle weakness associated with CTS occurs late in the disease process. In advanced cases, atrophy of the thenar musculature can be seen. The unlucky patient with symptoms progressed to this state is at high risk for permanent nerve damage and may require a tendon transfer to substitute for the loss of palmar abduction.

The clinician must be able to visualize the anatomic structures that make up the carpal tunnel. The carpal canal is bounded by the TCL volarly, the scaphoid tuberosity and the trapezium radially, the hook of the hamate and the pisiform ulnarly, and the volar radiocarpal ligament and volar ligamentous extensions between the carpal bones dorsally.^19,34 The carpal canal is traversed by the median nerve, the four flexor digitorum profundus tendons, the four flexor digitorum superficialis tendons, the flexor pollicis longus tendon, and the surrounding synovial membranes. Any condition that causes enlargement of the contents of the carpal canal (such as inflammation or edema) or occupies space within the canal (such as a tumor or hematoma) compresses the median nerve. This occurs because the structures that make up the carpal canal are relatively inelastic and do not expand as the contents of the canal enlarge. The resulting pressure compromises circulation within the substance of the nerve, leading to nerve ischemia, which in turn leads to the symptoms and signs seen in CTS.

Residual symptoms following carpal tunnel surgery are common, but in one of the author’s experience, true recurrences and failed surgeries are very rare. Although symptoms of CTS vary depending on the individual, age, and duration of symptoms, the most common symptom of carpal tunnel is numbness in the distribution of the median nerve, which is worse at night. This is usually confirmed by evidence of significant slowing of the nerve conduction through the carpal canal. When patients with residual symptoms are properly questioned, they usually recall that they did in fact have relief of their nocturnal numbness following release of the TCL. This indicates a successful treatment of their CTS; however, they may still be dissatisfied with the result if they still have symptoms that brought them to the physician in the first place. These symptoms might include arm pain, arm numbness and tingling, shooting pains into various parts of the arm and hands, and weakness. The symptoms might be reproducible when attempting to perform specific activities, giving rise to the notion that their condition is a repetitive motion injury. In the experience of the authors of this chapter, the vast majority of these patients are no longer suffering from CTS but rather have a more proximal nerve entrapment. There are several potential points of entrapment of the median nerve at the elbow, including pronator syndrome. If cervical radiculopathy can be ruled out, the problem may be attributed to compression at the level of the brachial plexus, the so-called thoracic outlet syndrome. This diagnosis is often made by exclusion and then treated with a trial of therapy to address the thoracic outlet. Within a few weeks the patient will often notice a significant decrease in pain and an increase in strength.46,47

The frequency and duration of treatment is highly variable after a carpal tunnel release. In most cases minimal therapy is required, with key contributions to postoperative care being wound/scar management and proper instructions in exercises to enhance tendon gliding, obtain full active range of motion (AROM), and minimize edema. The patient may need guidance on ergonomics and other principles to facilitate full return to work or other activities.10 All patients referred to therapy are instructed in a home exercise program appropriate to the phase of recovery and their individual needs.

In general, patients tend to do quite well after carpal tunnel release. However, because the extent of the damage to the median nerve cannot fully be known before surgery, predicting the exact outcome of carpal tunnel release is difficult. Patients with mild to moderate symptoms can expect full recovery of sensation and resolution of the numbness and tingling caused by entrapment of the nerve. Patients with more advanced disease who have significant sensibility loss and muscle weakness usually achieve significant improvement of their condition. Patients with muscle atrophy can expect a halt to progression of muscle wasting and in some cases can regain muscle mass.

The recovery of the median nerve directly relates to the success of the surgery. Ultrasonography postoperatively may be helpful in identifying the initial beneficial morphologic changes. Nerve conduction studies could take as long as 3 to 6 months to change.⁴⁸ Patients must understand that they may have some element of incisional pain after surgery, which can last as long as 3 to 6 months. They must also be informed that they will temporarily lose some strength in the hand, which usually improves after 3 to 6 months.

In general, patients may be referred to therapy anywhere from 1 to 3 weeks postoperatively. The timing of the first visit will dictate which tests are appropriate to perform and which should be deferred until a later time. The initial evaluation after carpal tunnel release includes the following:

After 3 weeks postoperatively, in addition to the above measurements, the evaluation can include:

The patient’s history is obtained by patient interview. Information to be noted in the history includes age, gender, hand dominance, cause of CTS, type and date of the carpal tunnel release, occupation, avocational interests, onset and description of symptoms before surgery, and notes regarding whether symptoms were unilateral or bilateral. The patient should be screened for medical or systemic problems that might contribute to the persistence of symptoms.

The patient is asked to quantify the pain on a scale from 0 (representing no pain) to 10 (indicating severe pain requiring medical attention). The patient is asked to rate the pain both at rest and with use. The quality of the patient’s pain is obtained by documenting the descriptive terms the patient uses when discussing the symptoms.⁴⁹

Edema of the hand is recorded either by volumetric circumferential or figure of eight measurements. If edema is profuse throughout the hand, then volumetric measurements can be taken provided that stitches have been removed and the patient has no open wounds. The volumetric assessment should be administered following the American Society of Hand Therapists (ASHT) guidelines. If edema is minimal or the stitches have not yet been removed, then circumferential measurements recorded in centimeters should be obtained at the distal wrist crease and the distal palmar crease (DPC). The figure of eight method for assessing hand edema has been shown to be as reliable and valid as the volumetric method, and may be easier to perform in a busy clinic than the volumetric method.⁵⁰

AROM measurements are obtained using a goniometer for the wrist and forearm. Individual finger AROM measurements may not be necessary when motion limitations are minimal. A global measurement of finger flexibility is obtained by measuring composite finger flexion to the DPC. The distance from the middle of the pulp of a finger to the DPC is measured in centimeters for each finger. Functional thumb opposition is recorded as the ability to oppose the thumb to each fingertip, and full composite flexion/opposition as the ability to touch the thumb to the DPC of the small finger. Full motion is recorded as “zero,” and lack of full motion as a negative number.

To prevent bowstringing (i.e., subluxing, or anterior displacement, of the flexor tendons through the healing TCL), simultaneous wrist/finger flexion measurements should be deferred until 3 weeks after an open incision surgery. As mentioned, bowstringing may be more of a concern with open procedures than with endoscopic procedures.⁵¹

“Sensibility testing is the evaluation of the ability to feel or perceive a stimulus applied to an area.”⁵² Sensibility assessment is completed using the Semmes-Weinstein pressure aesthesiometer kit (a five filament kit is adequate). This type of sensory test is a pressure threshold test. The patient is seated comfortably for testing with the forearm supinated and the hand supported on a towel roll. The therapist should occlude the patient’s vision during the test and instruct the patient to report when a finger is stimulated and which finger feels the stimulus. The volar fingertips and thumb pulp are tested starting with the 2.83 monofilament. “Each monofilament is applied perpendicular to the skin for 1.5 seconds and lifted for 1.5 seconds.”⁵² The therapist should apply monofilaments 2.83 and 3.61 three times to the same spot, and apply monofilaments 4.31 through 6.65 once. The lowest-numbered monofilament felt for each digit should be recorded on the evaluation form.⁵² Full hand mapping is rarely required after a carpal tunnel release.

“Two point discrimination values are most often normal in CTS, and if they are abnormal it indicates advanced disease.”^53,54 The therapist should complete two-point discrimination testing only if the patient demonstrates significant deficits on the Semmes-Weinstein Monofilament Test. Two point discrimination is an innervation density test.⁵³ The difference between the pressure threshold test and an innervation density test is the sensitivity of the pressure threshold test to gradual loss or improvement in nerve function versus an all-or-none response on an innervation density test.