eMedicine Specialties > Radiology > Musculoskeletal

Carpal Tunnel Syndrome

Patrick D Browning, MA, MD, Partner, Redwood Regional Medical Group; Clinical Staff, University of California at Davis Medical Center; Founder and Principle Partner, Conceptus Partners Consulting

Updated: Apr 16, 2009

Introduction

Background

Carpal tunnel syndrome (CTS) is defined as the impairment of motor and/or sensory function of the median nerve as it traverses through the carpal tunnel.

Carpal tunnel syndrome. Axial fast spin-echo T2-weighted MRI with fat saturation. Note the increased T2-weighted signal within the median nerve (arrow). A slightly increased cross sectional area of the nerve is noted but the nerve architecture is preserved, consistent with early or mild inflammation.

Recommendation 1

A course of nonoperative treatment is an option in patients diagnosed with carpal tunnel syndrome (CTS). Early surgery is an option when there is clinical evidence of median nerve denervation or the patient elects to proceed directly to surgical treatment. (Grade C, level V)

Recommendation 2

We suggest another nonoperative treatment or surgery when the current treatment fails to resolve the symptoms within 2-7 weeks. (Grade B, level I and II)

Recommendation 3

We do not have sufficient evidence to provide specific treatment recommendations for carpal tunnel syndrome when found in association with the following conditions: diabetes mellitus, coexistent cervical radiculopathy, hypothyroidism, polyneuropathy, pregnancy, rheumatoid arthritis, and carpal tunnel syndrome in the workplace. (Inconclusive, No evidence found)

Recommendation 4a

Local steroid injection or splinting is suggested when treating patients with carpal tunnel syndrome, before considering surgery. (Grade B, level I and II)

Recommendation 4b

Oral steroids or ultrasound are options when treating patients with carpal tunnel syndrome. (Grade C, level II)

Recommendation 4c

We recommend carpal tunnel release as treatment for carpal tunnel syndrome. (Grade A, level I)

Recommendation 4d

Heat therapy is not among the options that should be used to treat patients with carpal tunnel syndrome. (Grade C, level II)

Recommendation 4e

The following treatments carry no recommendation for or against their use: activity modifications, acupuncture, cognitive behavioral therapy, cold laser, diuretics, exercise, electric stimulation, fitness, Graston instrument, iontophoresis, laser, stretching, massage therapy, magnet therapy, manipulation, medications (including anticonvulsants, antidepressants, and nonsteroidal anti-inflammatory drugs [NSAIDs]), nutritional supplements, phonophoresis, smoking cessation, systemic steroid injection, therapeutic touch, vitamin B6 (pyridoxine), weight reduction, yoga. (Inconclusive, level II and V)

Recommendation 5

We recommend surgical treatment of carpal tunnel syndrome by complete division of the flexor retinaculum regardless of the specific surgical technique. (Grade A, level I and II)

Recommendation 6

We suggest that surgeons do not routinely use the following procedures when performing carpal tunnel release: skin nerve preservation (Grade B, level I); epineurotomy (Grade C, level II)

The following procedures carry no recommendation for or against use: flexor retinaculum lengthening, internal neurolysis, tenosynovectomy, ulnar bursa preservation. (Inconclusive, level II and V)

Recommendation 7

The physician has the option of prescribing preoperative antibiotics for carpal tunnel surgery. (Grade C, level III)

Recommendation 8

We suggest that the wrist not be immobilized postoperatively after routine carpal tunnel surgery. (Grade B, level II)

We make no recommendation for or against the use of postoperative rehabilitation. (Inconclusive, level II)

Recommendation 9
We suggest physicians use one or more of the following instruments when assessing patients’ responses to CTS treatment for research:

• Boston Carpal Tunnel Questionnaire (disease-specific)
• DASH—Disabilities of the Arm, Shoulder, and Hand (region-specific; upper limb)
• MHQ—Michigan Hand Outcomes Questionnaire (region-specific; hand/wrist)
• Patient Evaluation Measure (region-specific; hand)
• SF-12 or SF-36 Short Form Health Survey (generic; physical health component for global health impact) (Grade B, level I, II, and III)

Pathophysiology

The most common cause of carpal tunnel syndrome is chronic repetitive stress upon the carpal tunnel, and thus the median nerve within it. This stress can result from abnormal positioning of the wrist as occurs during typing, repeated flexion or extension stress (eg, carpentry, carpet weaving), or rapid jarring of the wrist (eg, operating a jackhammer). Fractures or dislocations of the wrist, soft-tissue injuries or abnormalities, infection, infiltrative disease, or intraneural hemorrhage also may cause CTS.

Frequency

United States

It has been estimated that 4-10 million persons in the United States have carpal tunnel syndrome.² A prevalence of 56.77% has been reported in workers who hold data entry/typing positions.³  As many as 50% of cases are bilateral.

Mortality/Morbidity

• Mortality: The likelihood of mortality resulting from carpal tunnel syndrome or complications of conservative treatment is exceedingly low. A small risk of death is associated with attempted surgical relief. Deaths are likely to be associated with the patient's prior health status and complications related to anesthesia. Mortality risk has no doubt decreased with the increasing acceptance of endoscopic techniques for carpal tunnel release and the subsequent decrease in both general anesthesia use and time under anesthesia.
• Morbidity: Morbidity of CTS is extremely variable and depends highly on duration and severity at presentation, cause, success of conservative therapy (if any), general preoperative health and attitude of the patient, type of surgical release, and numerous psychosocial factors postoperatively. Throughout the medical literature, a large number of articles have shown a correlation between these factors and treatment outcome. Conservative therapy failure rates from 1-50% and surgical failure rates from 2-31% have been reported.

Sex

There is a strong female predominance with a male-to-female ratio of 1:3-5.

Age

Rates of CTS increase with age, peaking in middle age (45-54 years) and then declining.³ However, several other factors influence age of onset.

Anatomy

Knowledge of carpal tunnel anatomy is important in understanding the pathophysiology of the syndrome. The carpus (composed of the carpal bones) has a concave bony contour on its flexor surface and is covered by the flexor retinaculum. This structure forms the floor and walls of the carpal tunnel and the rigid flexor retinaculum forms its roof. The flexor retinaculum, or transverse carpal ligament, attaches to the scaphoid tubercle, the ridge of the trapezium, and the ulnar aspect of the hook of the hamate and pisiform (see Images 1 through 4 ).

Carpal tunnel syndrome. Carpal and Guyon tunnels. Drawing showing the proximal level of the carpal tunnel delimited by the pisiform (P) and the scaphoid (S). The flexor retinaculum (medium gray region) forms the roof of the carpal tunnel and the floor of the Guyon tunnel. The palmar carpal ligament (dark gray region) forms the volar boundary of the Guyon tunnel. * = flexor pollicis longus tendon, * = flexor carpi radialis tendon. From Martinoli C, Bianchi S, et al. US of nerve entrapments in osteofibrous tunnels of the upper and lower limbs. Radiographics 2000; 20:S199-S217. Used by permission of the authors and RSNA.

Carpal tunnel syndrome. Carpal and Guyon tunnels. Transverse 5-12-MHz ultrasound scan corresponding to Image 1 shows the proximal level of the carpal tunnel delimited by the pisiform (P) and the scaphoid (S). The flexor tendons and median nerve (MN) extend through the carpal tunnel, with the nerve lying palmar and radial. The flexor retinaculum (open arrowheads) forms the roof of the carpal tunnel and the floor of the Guyon tunnel. At the level of the pisiform, the ulnar nerve (U) courses medial to the ulnar artery (solid arrowhead) within the Guyon tunnel. * = flexor pollicis longus tendon. From Martinoli C, Bianchi S, et al. US of nerve entrapments in osteofibrous tunnels of the upper and lower limbs. Radiographics 2000; 20:S199-S217. Used by permission of the authors and RSNA.

Carpal tunnel syndrome. Carpal and Guyon tunnels. Drawing showing the distal level of the carpal tunnel delimited by the hook of the hamate (H) and the tubercle of the trapezium (T). The flexor retinaculum (medium gray region) forms the roof of the carpal tunnel. From Martinoli C, Bianchi S, et al. US of nerve entrapments in osteofibrous tunnels of the upper and lower limbs. Radiographics 2000; 20:S199-S217. Used by permission of the authors and RSNA.

Carpal tunnel syndrome. Carpal and Guyon tunnels. Transverse 5-12-MHz ultrasound scan corresponding to Image 3 shows the distal level of the carpal tunnel delimited by the hook of the hamate (H) and the tubercle of the trapezium (T). The flexor retinaculum (open arrowheads) forms the roof of the carpal tunnel. The flexor tendons and median nerve (MN) extend through the carpal tunnel, with the nerve lying palmar and radial. At the level of the pisiform, the ulnar nerve courses medial to the ulnar artery (solid arrowhead) within the Guyon tunnel. At the level of the hamate, the ulnar nerve divides into two terminal branches, a deep motor branch (curved arrow) and a superficial sensory branch (straight arrow). From Martinoli C, Bianchi S, et al. US of nerve entrapments in osteofibrous tunnels of the upper and lower limbs. * = flexor pollicis longus tendon. Radiographics 2000; 20:S199-S217. Used by permission of the authors and RSNA.

All 8 flexor tendons are covered with a common synovial sheath. The flexor pollicis longus tendon, contained in its own synovial sheath, is located on the radial aspect of the flexor tendons within the carpal tunnel. The median nerve resides just under the flexor retinaculum and abuts its inner surface. It is located on the lateral side of the flexor digitorum superficialis between the flexor tendon of the middle finger and the flexor carpi radialis.

The nerve is round or oval at the level of the distal radius; it becomes elliptical at the pisiform and hamate. Both its position and its morphology are altered during flexion and extension. With the wrist in a neutral position, the median nerve lies anterior to the flexor digitorum superficialis tendon of the index finger or posterolaterally between the flexor digitorum tendon of the index finger and flexor pollicis longus tendon.

The nerve is forced against the transverse carpal ligament in dorsiflexion or palmoflexion of the wrist. In wrist extension, the median nerve assumes a more anterior position, deep to the flexor retinaculum and superficial to the flexor digitorum superficialis tendon of the index finger. In wrist flexion, the median nerve can be found anterior to the flexor retinaculum or between the flexor digitorum superficialis tendons of the index finger and thumb or middle and ring fingers. In the flexed position, the elliptical shape of the median nerve flattens.

Alteration of median nerve morphology is less pronounced in wrist extension. As much as 20 mm of excursion of the median nerve can occur and frictional forces between the median nerve, adjacent tendons, and the transverse carpal ligament compound the potential irritation caused by morphologic plasticity during flexion and extension.

Presentation

Clinical presentation typically includes pain and numbness, often with increased nocturnal pain and/or burning. The thumb, index finger, middle finger, and radial side of the ring finger are most commonly affected.

• Sensory findings range from minimal loss of sensation to complete anesthesia.
• Muscular atrophy and function loss are late findings, although the abductor pollicis brevis muscle may show earlier involvement.
• Direct pressure measurement in patients with carpal tunnel syndrome reveals increased pressures in the carpal canal (up to 32 mm Hg, compared with 2.5 mm Hg in asymptomatic patients). Pressure changes also can be recorded in extremes of dorsiflexion and palmoflexion.
• Axial CT studies of patients with carpal tunnel syndrome reveal a decrease in the cross-sectional area of the carpal canal. Various processes can cause decreased volume of the carpal tunnel, including infections, tenosynovitis of the flexor tendons, Colles fracture, and fracture-dislocation of the radiocarpal, carpal, and carpometacarpal joints. These processes also may cause posttraumatic scarring, fibrosis, or both. Inflammatory processes causing decreased volume within the carpal tunnel include rheumatoid arthritis, gout, pseudogout, amyloid deposition, and granulomatous infection. All of these may produce a tenosynovitis with hyperplastic synovium.
• Tumors of the median nerve (eg, neuromas, fibromas, hamartomas) and tumors extrinsic to the median nerve (eg, ganglion cysts, lipomas, hemangiomas) can create space-occupying masses within the carpal canal.
• Disorders that enlarge the normal structures within the carpal tunnel and may increase the risk for carpal tunnel syndrome include acromegaly, hypothyroidism, pregnancy, diabetes mellitus, and systemic lupus erythematosus. Both the frequency and the severity of carpal tunnel syndrome may be greater in persons with metabolic syndrome.⁴
• For reasons not yet understood, volumetric increases occasionally are seen in women who are postmenopausal.
• Developmental causes of increased carpal tunnel pressures include a persistent median artery, hypertrophied lumbricals, anomalous muscles, and a distal positioning of the flexor digitorum superficialis muscle. All of these conditions can produce carpal tunnel syndrome as a result of compression or of irritation, edema, and subsequent swelling of the median nerve.
• Median nerve damage proximal to the carpal tunnel is an important consideration in the differential diagnosis of carpal tunnel syndrome. Such damage may affect the palmocutaneous branch of the median nerve, thereby causing weakness of the corresponding flexor muscles of the forearm, including the flexor pollicis longus. This contrasts with carpal tunnel syndrome, in which the terminal phalanx of the thumb demonstrates normal flexion without motor impairment. Although the median nerve is composed of both sensory and motor nerve fibers, sensory fibers predominate at the level of the carpal tunnel, explaining the initial findings of sensory deficit and numbness.
• As the disease progresses, wasting and weakness of the thenar muscles occur, with decreased ability to oppose the thumb and anesthesia of the 3.5 digits on the radial side of the hand. No anesthesia of the thenar eminence occurs because the cutaneous branch of the median nerve supplies this structure.

Preferred Examination

The clinical examination is the most important part of the evaluation for CTS. Guidelines regarding the clinical diagnosis have been issued by the American Academy of Orthopaedic Surgeons⁵ and the Work Loss Data Institute.³

A positive Tinel sign (tingling in the digits supplied by the median nerve) is an indication of nerve entrapment. The Phalen test, tourniquet compression, and direct compression also are used to detect signs of median nerve entrapment. A positive flick sign (having to shake the hand for relief) is suggestive of CTS.³  
 
Electromyography (EMG) and nerve conduction studies are useful for confirming the diagnosis of CTS and are most helpful in localizing the level and determining the severity of median nerve compression. A prolonged sensory conduction or distal motor latency test provides quantitative information in this regard. Electrodiagnostic tests such as EMG and nerve conduction studies are 85-90% accurate in patients with carpal tunnel syndrome, with a false-negative rate of 10-15%. Therefore, in cases of clinically symptomatic CTS with normal EMG and conduction findings, radiology studies can have a strong complementary role in diagnosis.⁶

Of radiologic imaging methods, MRI has consistently shown the greatest sensitivity and specificity in the diagnosis and evaluation of carpal tunnel syndrome.

Plain radiographs have no role in the evaluation of CTS except for their ability to show the anatomic relationship of the carpal bones and evidence of severe prior trauma or fractures.

Helical CT is more sensitive than plain radiography in revealing subtle bony trauma and misalignments and can be used to measure the cross-sectional area of the carpal tunnel.

Ultrasound can be useful in the evaluation of soft tissues of the carpal tunnel and the median nerve. An increasing number of studies have supported early suggestions that measurement of the cross-sectional area and morphology of the median nerve with high-resolution sonography compares favorably with physical examination alone; thus, this technique is proving to be a useful tool for diagnosis. Additionally, ultrasound may prove to be a beneficial adjunct in the conservative treatment of CTS.

Limitations of Techniques

As noted above, electrodiagnostic tests such as EMG and nerve conduction studies are 85-90% accurate in patients with carpal tunnel syndrome, with a false-negative rate of 10-15%.

Plain radiographs usually do not reveal ligamentous or soft tissue abnormalities but may be useful to exclude frank fractures or chronic degenerative/posttraumatic morphologic abnormalities.

CT does not reveal ligamentous or soft tissue abnormalities to any degree. Axial scanners are even more limited since they do not allow adequate multiplanar or 3-dimensional reconstructions.

Ultrasound is operator and equipment dependent. Although musculoskeletal ultrasound using high-frequency transducers is widely used in Europe, familiarity with and training in the performance and interpretation of carpal tunnel ultrasonography is still variable, more so in the United States.

MRI is useful for the evaluation of all of the intrinsic structures of the wrist (including the carpal bones) but may not be widely available, is technique and equipment dependent, can require up to 45 minutes to complete an examination, and has a number of contraindications (eg, cardiac pacemakers, older aneurysm clips, new stents or aortic valves, ferromagnetic ocular fragments).

Patient Education: For excellent patient education resources, visit eMedicine's Hand, Wrist, Elbow, and Shoulder Center and Arthritis Center. Also, see eMedicine's patient education article Carpal Tunnel Syndrome.

Differential Diagnoses

Other Problems to Be Considered

Cervical radiculopathy
Proximal median nerve damage
Arthritic conditions
Muscle and nerve diseases

 

Radiography

Findings

Plain radiographs are useful for evaluating the wrist and carpal bones for trauma and fractures (especially the hook of the hamate and the tubercle of the trapezium), severe osteoarthritis, and other arthropathies.

Degree of Confidence

Plain films are of limited use in diagnosing or evaluating carpal tunnel syndrome. Plain films do not effectively visualize the small soft-tissue structures of the carpal tunnel, many of which can be involved in the syndrome. A carpal tunnel view of the wrist on plain films provides only a very rough idea of the cross-sectional area of the carpal tunnel.

Computed Tomography

Findings

CT is useful for its ability to display and evaluate the cross-sectional volume of the carpal tunnel and for detecting subtle calcification in the tendons within the canal. CT also provides an excellent tool for evaluating the carpal bones through multiplanar and 3-dimensional reconstructions.

Degree of Confidence

CT is limited in its ability to visualize the median nerve and tendons of the carpal tunnel well enough to allow a definitive differential diagnosis to be rendered. Therefore, other methods of visualizing the soft tissues of the carpal tunnel are preferable.

Magnetic Resonance Imaging

Carpal tunnel syndrome. Normal findings on an axial spin-echo T1 MRI of the carpal tunnel showing the intermediate signal intensity of the median nerve (arrow).

Carpal tunnel syndrome. Normal findings of isointense-to-hypointense appearance of the median nerve on fast spin-echo T2-weighted MRI (arrow). Note the fairly well-defined nerve fascicles within the median nerve sheath.

Carpal tunnel syndrome. Axial fast spin-echo T2-weighted MRI with fat saturation. Note the increased T2-weighted signal within the median nerve (arrow). A slightly increased cross sectional area of the nerve is noted but the nerve architecture is preserved, consistent with early or mild inflammation.

Carpal tunnel syndrome. Fast spin-echo T2-weighted MRI illustrates more pronounced increased signal within the median nerve (arrow). Note the small amount of fluid within the carpal tunnel, a secondary sign of inflammation. Slightly less optimal fat saturation is noted than on other images, which is a common occurrence.

Carpal tunnel syndrome. Axial fast spin-echo T2-weighted MRI with greater increase in signal and loss of definition within the nerve (arrow). Inflammatory change is noted within the carpal tunnel, adjacent to the flexor digitorum superficialis tendons. The appearance is consistent with pronounced inflammatory change within the carpal tunnel.

Findings

• In patients with flexor tenosynovitis, axial MRI demonstrates bowing of the flexor retinaculum.
• Inflamed synovium and tendon sheaths demonstrate low signal intensity on T1-weighted images and increased signal intensity on T2-weighted, T2*-weighted, and short tau inversion recovery (STIR) sequences.
• Regardless of the etiology of carpal tunnel syndrome, changes in the median nerve are similar and include the following:
  • Diffuse swelling or segmental enlargement of the median nerve may be demonstrated (usually seen best at the level of the pisiform).
  • The median nerve may flatten (usually demonstrated best at the level of the hamate).
  • Palmar bowing of the flexor retinaculum may be noted (usually demonstrated best at the level of the hamate).
  • Increased T2-weighted signal intensity within the median nerve occurs, which is demonstrated best on axial fast spin-echo (FSE) T2-weighted images (see Images 5 through 9). If FSE signal sequences are not available, axial gradient-recalled echo (GRE) or inversion recovery (IR) sequences also are sensitive to the increased edema in the median nerve that accompanies carpal tunnel syndrome.
• MRI also is useful in detecting and characterizing space-occupying lesions, such as neuromas, ganglion cysts, lipomas, and hemangiomas.
• Enlargement or swelling of the median nerve proximal to the carpal tunnel, termed a pseudoneuroma, has been documented using MRI.
• Flow-sensitive sequences or dynamic contrast-enhanced MRI can detect a circulatory disturbance causing carpal tunnel syndrome, which is a cause separate from deformation or compression of the median nerve.
• One of two abnormal patterns of median nerve enhancement is usually demonstrated: marked enhancement of the nerve (attributed to hypervascular edema) or noticeable lack of enhancement (attributed to nerve ischemia).
• As with the symptoms of carpal tunnel syndrome, MRI findings in the syndrome may vary with wrist position: flexion or extension of the wrist during the scan can alter the visualization of the median nerve from marked enhancement to complete lack of enhancement, presumably because of mechanical obstruction of blood flow to the  nerve. These actions are associated with exacerbation of clinical symptoms.
• Attempted surgical therapy for carpal tunnel syndrome may result in incomplete release of the flexor retinaculum. This can be detected by a residual increase in T2 signal of the median nerve within the carpal tunnel and by direct visualization of the still-connected fibers of the retinaculum.
• Transverse carpal ligament release from the hook of the hamate can cause the contents of the carpal canal and/or the flexor tendons to demonstrate a volar convexity caused by the loss of the normal roof support of the flexor retinaculum.
• In addition to incomplete release of the flexor retinaculum, postoperative MRI changes in failed carpal tunnel surgery include excessive fat within the carpal tunnel, neuromas, scarring, and persistent neuritis. A normal postoperative finding is widening of the fat stripe posterior to the flexor digitorum profundus tendons.
• MRI studies following carpal tunnel release may demonstrate an increase in carpal tunnel volume of up to 24%, often accompanied by a change in shape from oval to circular, resulting in increased anteroposterior and mediolateral diameters.

Degree of Confidence

Early detection of the subtle changes of carpal tunnel syndrome requires soft tissue discrimination not possible using standard radiographs or CT. The ability to evaluate the cross sectional morphologic and signal characteristics of the medial nerve and adjacent structures makes MRI invaluable in characterizing both normal anatomy and abnormal pathology in the carpal tunnel.

Significant differences often are present in patients with carpal tunnel syndrome, despite the subjective flattening of the median nerve at the lateral and distal carpal row. Flattening ratios have been used to document statistically significant flattening of the median nerve at the level of the hamate. The median nerve may display enlargement or dilation at the level of the pisiform and concomitant compression and flattening at the level of the hook of the hamate.

False Positives/Negatives

Since carpal tunnel involvement is bilateral in as many as 50% of patients, comparison with the contralateral wrist can be misleading. Alterations in the median nerve signal intensity may represent edema or demyelination within neural fibers and thus are somewhat nonspecific. Both T1 and T2 signal intensities may be decreased when fibrosis of the median nerve is present. Evaluation of swelling is accomplished by comparing the cross-sectional area of the median nerve at the level of the pisiform and hamate to the cross-sectional area of the median nerve at the level of the distal radius.

Ultrasonography

Findings

The development of high-resolution ultrasound (US) transducers (7-15 MHz) has allowed evaluation of normal and abnormal US appearances of the median nerve and adjacent tendons. High-resolution US allows noninvasive imaging of the carpal tunnel and its contents. It has several advantages over MRI, including being relatively fast and inexpensive and allowing additional dynamic and blood flow imaging with relatively little additional time.

On transverse US scans, the normal median nerve is elliptical and flattens progressively as it courses distally. Median nerve compression is revealed on US by the classic triad of nerve flattening in the distal tunnel, nerve swelling at the level of the distal radius (less frequently in the proximal tunnel), and palmar bowing of the flexor retinaculum.

Since the shape of the nerve varies as it passes through the tunnel, indexes have been introduced to better quantify abnormal findings; a nerve cross-sectional area greater than 9 mm² at the level of the proximal tunnel is reported to be the best criterion for the diagnosis.

Degree of Confidence

A good correlation has been demonstrated between the measured US area of the median nerve and the degree of findings of electromyography or functional outcome after surgery. Reduced transverse sliding of the nerve beneath the retinaculum during flexion and extension of the index finger also may be seen, but this sign is harder to quantify and may be too subjective. Only a few studies have compared US and MRI in evaluating carpal tunnel syndrome, but these demonstrated that US is capable of producing results similar to MRI. MRI has been shown to be superior to US in identification of subtle cases and MRI demonstrates better sensitivity than color and power Doppler US in showing changes caused by nerve edema and blood perfusion abnormalities.

Intervention

In a single-center, randomized, controlled trial of 128 patients with carpal tunnel syndrome randomized to open surgery or 2-portal endoscopic surgery, the 2 techniques were found to be equally successful. At the 5-year follow-up, 11 patients who received open surgery and 10 patients who underwent endoscopic surgery reported persistent pain, and 3 patients in each treatment group had repeat surgery because of persistent or recurring symptoms.⁷

In a meta-analysis of surgical treatment versus nonsurgical treatment for carpal tunnel syndrome, Verdugo et al concluded, based on their findings, that surgery resulted in significantly better relief of symptoms than splinting. The investigators found that a significant percentage of those persons treated medically subsequently required surgery, whereas the risk of reoperation was low in those patients initially treated surgically.⁸  

See also Carpal Tunnel Syndrome in the eMedicine Orthopedic Surgery section.

Multimedia

Media file 1: Carpal tunnel syndrome. Carpal and Guyon tunnels. Drawing showing the proximal level of the carpal tunnel delimited by the pisiform (P) and the scaphoid (S). The flexor retinaculum (medium gray region) forms the roof of the carpal tunnel and the floor of the Guyon tunnel. The palmar carpal ligament (dark gray region) forms the volar boundary of the Guyon tunnel. * = flexor pollicis longus tendon, * = flexor carpi radialis tendon. From Martinoli C, Bianchi S, et al. US of nerve entrapments in osteofibrous tunnels of the upper and lower limbs. Radiographics 2000; 20:S199-S217. Used by permission of the authors and RSNA.

Media file 2: Carpal tunnel syndrome. Carpal and Guyon tunnels. Transverse 5-12-MHz ultrasound scan corresponding to Image 1 shows the proximal level of the carpal tunnel delimited by the pisiform (P) and the scaphoid (S). The flexor tendons and median nerve (MN) extend through the carpal tunnel, with the nerve lying palmar and radial. The flexor retinaculum (open arrowheads) forms the roof of the carpal tunnel and the floor of the Guyon tunnel. At the level of the pisiform, the ulnar nerve (U) courses medial to the ulnar artery (solid arrowhead) within the Guyon tunnel. * = flexor pollicis longus tendon. From Martinoli C, Bianchi S, et al. US of nerve entrapments in osteofibrous tunnels of the upper and lower limbs. Radiographics 2000; 20:S199-S217. Used by permission of the authors and RSNA.

Media file 3: Carpal tunnel syndrome. Carpal and Guyon tunnels. Drawing showing the distal level of the carpal tunnel delimited by the hook of the hamate (H) and the tubercle of the trapezium (T). The flexor retinaculum (medium gray region) forms the roof of the carpal tunnel. From Martinoli C, Bianchi S, et al. US of nerve entrapments in osteofibrous tunnels of the upper and lower limbs. Radiographics 2000; 20:S199-S217. Used by permission of the authors and RSNA.

Media file 4: Carpal tunnel syndrome. Carpal and Guyon tunnels. Transverse 5-12-MHz ultrasound scan corresponding to Image 3 shows the distal level of the carpal tunnel delimited by the hook of the hamate (H) and the tubercle of the trapezium (T). The flexor retinaculum (open arrowheads) forms the roof of the carpal tunnel. The flexor tendons and median nerve (MN) extend through the carpal tunnel, with the nerve lying palmar and radial. At the level of the pisiform, the ulnar nerve courses medial to the ulnar artery (solid arrowhead) within the Guyon tunnel. At the level of the hamate, the ulnar nerve divides into two terminal branches, a deep motor branch (curved arrow) and a superficial sensory branch (straight arrow). From Martinoli C, Bianchi S, et al. US of nerve entrapments in osteofibrous tunnels of the upper and lower limbs. * = flexor pollicis longus tendon. Radiographics 2000; 20:S199-S217. Used by permission of the authors and RSNA.

Media file 5: Carpal tunnel syndrome. Normal findings on an axial spin-echo T1 MRI of the carpal tunnel showing the intermediate signal intensity of the median nerve (arrow).

Media file 6: Carpal tunnel syndrome. Normal findings of isointense-to-hypointense appearance of the median nerve on fast spin-echo T2-weighted MRI (arrow). Note the fairly well-defined nerve fascicles within the median nerve sheath.

Media file 7: Carpal tunnel syndrome. Axial fast spin-echo T2-weighted MRI with fat saturation. Note the increased T2-weighted signal within the median nerve (arrow). A slightly increased cross sectional area of the nerve is noted but the nerve architecture is preserved, consistent with early or mild inflammation.

Media file 8: Carpal tunnel syndrome. Fast spin-echo T2-weighted MRI illustrates more pronounced increased signal within the median nerve (arrow). Note the small amount of fluid within the carpal tunnel, a secondary sign of inflammation. Slightly less optimal fat saturation is noted than on other images, which is a common occurrence.

Media file 9: Carpal tunnel syndrome. Axial fast spin-echo T2-weighted MRI with greater increase in signal and loss of definition within the nerve (arrow). Inflammatory change is noted within the carpal tunnel, adjacent to the flexor digitorum superficialis tendons. The appearance is consistent with pronounced inflammatory change within the carpal tunnel.

References

1. American Academy of Orthopaedic Surgeons Work Group Panel. AAOS Clinical Guidelines on the Treatment of Carpal Tunnel Syndrome. AAOS Now October 2008 Issue (10/09/08). American Academy of Orthopaedic Surgeons. Available at http://www.aaos.org/news/aaosnow/oct08/clinical3.asp. Accessed April 16, 2009.

2. Lawrence RC, Felson DT, Helmick CG, Arnold LM, Choi H, Deyo RA, et al. Estimates of the prevalence of arthritis and other rheumatic conditions in the United States. Part II. Arthritis Rheum. Jan 2008;58(1):26-35. [Medline].

3. Work Loss Data Institute. Carpal tunnel syndrome (acute & chronic). Corpus Christi, TX: Work Loss Data Institute; 2007.

4. Balci K, Utku U. Carpal tunnel syndrome and metabolic syndrome. Acta Neurol Scand. Aug 2007;116(2):113-7. [Medline].

5. American Academy of Orthopaedic Surgeons. American Academy of Orthopaedic Surgeons clinical guideline on diagnosis of carpal tunnel syndrome. National Guidelines Clearinghouse. Available at http://www.guideline.gov/summary/summary.aspx?ss=15&doc_id=10849&string=carpal+AND+tunnel. Accessed November 18, 2008.

6. Padua L, Pazzaglia C, Caliandro P, Granata G, Foschini M, Briani C, et al. Carpal tunnel syndrome: ultrasound, neurophysiology, clinical and patient-oriented assessment. Clin Neurophysiol. Sep 2008;119(9):2064-9. [Medline].

7. [Best Evidence] Atroshi I, Hofer M, Larsson GU, Ornstein E, Johnsson R, Ranstam J. Open compared with 2-portal endoscopic carpal tunnel release: a 5-year follow-up of a randomized controlled trial. J Hand Surg [Am]. Feb 2009;34(2):266-72. [Medline].

8. [Best Evidence] Verdugo RJ, Salinas RA, Castillo JL, Cea JG. Surgical versus non-surgical treatment for carpal tunnel syndrome. Cochrane Database Syst Rev. Oct 8 2008;CD001552. [Medline].

9. Allmann KH, Horch R, Uhl M, et al. MR imaging of the carpal tunnel. Eur J Radiol. Sep 1997;25(2):141-5. [Medline].

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Keywords

carpal tunnel syndrome, median nerve injury, wrist injury, repetitive stress syndrome, carpus, carpal bone, flexor retinaculum, traverse carpal ligament, scaphoid tubercle, trapezium, flexor digitorum, flexor tendons, flexor pollicis longus, flexor tenosynovitis

Contributor Information and Disclosures

Author

Patrick D Browning, MA, MD, Partner, Redwood Regional Medical Group; Clinical Staff, University of California at Davis Medical Center; Founder and Principle Partner, Conceptus Partners Consulting
Patrick D Browning, MA, MD is a member of the following medical societies: American College of Radiology and Radiological Society of North America
Disclosure: Nothing to disclose.

Medical Editor

Michael A Bruno, MD, Associate Professor, Departments of Radiology and Medicine, Pennsylvania State University College of Medicine; Director, Radiology Quality Management Services, Milton S Hershey Medical Center, Pennsylvania State University College of Medicine
Michael A Bruno, MD is a member of the following medical societies: American College of Radiology, American Roentgen Ray Society, Association of University Radiologists, Radiological Society of North America, Society of Nuclear Medicine, and Society of Skeletal Radiology
Disclosure: Nothing to disclose.

Pharmacy Editor

Bernard D Coombs, MB, ChB, PhD, Consulting Staff, Department of Specialist Rehabilitation Services, Hutt Valley District Health Board, New Zealand
Disclosure: Nothing to disclose.

Managing Editor

William R Reinus, MD, MBA, FACR, Professor of Radiology, Temple University; Chief of Musculoskeletal and Trauma Radiology, Vice Chair, Department of Radiology, Temple University Hospital
William R Reinus, MD, MBA, FACR is a member of the following medical societies: Alpha Omega Alpha, American College of Radiology, American Roentgen Ray Society, Radiological Society of North America, and Sigma Xi
Disclosure: Nothing to disclose.

CME Editor

Robert M Krasny, MD, Consulting Staff, Department of Radiology, Resolution Imaging Medical Corporation
Robert M Krasny, MD is a member of the following medical societies: American Roentgen Ray Society and Radiological Society of North America
Disclosure: Nothing to disclose.

Chief Editor

Felix S Chew, MD, MBA, EdM, Professor, Department of Radiology, Vice Chairman for Radiology Informatics, Section Head of Musculoskeletal Radiology, University of Washington
Felix S Chew, MD, MBA, EdM is a member of the following medical societies: American Roentgen Ray Society, Association of University Radiologists, and Radiological Society of North America
Disclosure: Nothing to disclose.

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