Carpal tunnel syndrome

Question 1

What forms the carpal tunnel anatomically?

Answer 1

The carpal tunnel is formed by the transverse carpal ligament superiorly and the carpal bones inferiorly

Question 2

What passes through the carpal tunnel?

Answer 2

The median nerve, accompanied by the nine flexor tendons of the forearm musculature, must pass through this anatomic tunnel

Question 3

Where do we tend to find an inflamed and compressed median nerve?

Answer 3

• Inflammation and compression of the median nerve most commonly occurs within the carpal tunnel
• Rarely, median entrapment can also occur more proximally in the region of the elbow or just distal to the elbow

Question 4

Gender effect on CTS

Answer 4

CTS is more frequent in females, with a female-to-male ratio of approximately 3:1

Question 5

Prevalence of CTS

Answer 5

The estimated prevalence of CTS in the general population is 1 to 5 percent.

Question 6

What are risk factor for carpal tunnel syndrome?

Answer 6

Risk factors – Risk factors for CTS include the following:
*Genetic predisposition
*Diabetes mellitus
*Osteoarthritis and rheumatoid arthritis
*Obesity
*Thyroid disease
*Pregnancy (particularly third trimester)
*Trauma to the wrist
*Aromatase inhibitor use
*Occupational biomechanical factors involving the hand and wrist, particularly repetition, forceful exertion, and vibration
- The role of repetitive hand/wrist use and workplace factors in the development of CTS is controversial

Question 7

Occupations with high risk of developing CTS

Answer 7

Occupational categories with particularly high risk of CTS include production and manufacturing, office and administrative support, and food processing and preparation

Question 8

What is carpal tunnel syndrome?

Answer 8

The complex of symptoms and signs brought on by compression of the median nerve as it travels through the carpal tunnel

Question 9

What are clinical symptoms of carpal tunnel syndrome?

Answer 9

• Pain or paresthesia (numbness and tingling) in a distribution that includes the median nerve territory, with involvement of the first three digits and the radial half of the fourth digit
• Symptoms are typically worse at night and characteristically awaken affected patients from sleep
• Pain may be localized to the wrist, involve the entire hand, or radiate proximally to as high as the shoulder

Question 10

What are provoking features for carpal tunnel syndrome?

Answer 10

CTS symptoms are often provoked by activities that involve flexing or extending the wrist or raising the arms

Question 11

What are severe manifestations of carpal tunnel syndrome?

Answer 11

• Fixed sensory loss is usually a late finding characterized by a distinctive clinical pattern that involves the median-innervated fingers and spares the thenar eminence (bulge that can be seen at the base of the thumb. It’s made up of three separate muscles)
• In severe CTS, motor involvement leads to complaints of weakness or clumsiness when using the hands. Clinical signs may include weakness of thumb abduction and opposition and atrophy of the thenar eminence

Question 12

Differential diagnosis of carpal tunnel syndrome

Answer 12

The most common disorder than can mimic CTS is cervical radiculopathy, particularly with C6 or C7 nerve root involvement

Question 13

Why is thenar eminence sparred in carpal tunnel syndrome?

Answer 13

Palmar branch of the median nerve does not pass through the carpal tunnel, so its not affected

Question 14

How can one confirm the diagnosis of CTS?

Answer 14

• Electrodiagnostic testing is very sensitive for confirming the diagnosis of CRS
• Nerve conduction studies (NCS), often supplemented with needle electromyography (EMG)
• Nerve conduction studies are especially helpful with sensitivity and specificity reaching 80-90 and 95% respectively

Question 15

What can CTS severity be divided into?

Answer 15

Low. moderate, severe

Question 16

Describe low CTS siverity symptoms

Answer 16

• Tingling or discomfort in median nerve distribution
• No sensory loss or weakness
  CTS symptoms do not disrupt sleep
• No difficulty with hand function or ADLs

Question 17

Describe moderate CTS severity symptoms

Answer 17

• Sensory loss in median distribution
• CTS symptoms (sensory loss or pain) interfere slightly with hand function but patient is able to perform all ADLs
• Nocturnal symptoms may occasionally but not routinely disrupt sleep

Question 18

Describe severe CTS severity symptoms

Answer 18

• Weakness in the median distribution, or
• CTS symptoms disrupt one or more ADLs; patient is unable to carry out all previous activities, or
• Nocturnal symptoms routinely disrupt sleep

Question 19

What are available treatments for CTS?

Answer 19

• Non surgical approaches (wrist splinting in a neutral position during night time and glucocorticoid injection)
• Surgical approach (Open carpal tunnel release and endoscopic carpal tunnel release, similar success rates)

Question 20

Which therapies should be avoided for CTS?

Answer 20

• NSAIDs and other oral medications (not effective)
• No benefit for diuretics or vitamin B6
• Electrical, magnetic, and laser therapy
• Perineural dextrose injections

Question 21

Which patients are selected for surgery for CTS?

Answer 21

Moderate or severe symptoms and electrodiagnostic evidence of severe median nerve injury (denervation or axon loss)

Question 22

What are clinical tests that can be performed on patients to determine if they have CTS?

Answer 22

• Phalen test (3rd)
• Tinel test (4th)
• Manual carpal compression (2nd)
• Hand elevation test (most accurate)

Question 23

How is hand elevation test performed for CTS?

Answer 23

The hand elevation test involves having the patient raise the hands above the head for one minute. The test is positive if it reproduces the symptoms of CTS.

Question 24

How is phalen test performed?

Answer 24

• The Phalen maneuver is performed by having the patient bring the dorsal surfaces of the hands against each other to provide hyperflexion of the wrist while the elbows remain flexed
• The flexed position is held for one minute
• A positive Phalen sign is defined as pain and/or paresthesia in the median-innervated fingers

Question 25

Manual carpal compression procedure

Answer 25

• The manual carpal compression, or Durkan test is performed by applying pressure over the transverse carpal ligament for 30 seconds
• Pain or paresthesia indicates a positive result

Question 26

Tilen test procedure

Answer 26

• Involves firm percussion/tapping performed over the course of the median nerve just proximal to or on top of the carpal tunnel
• A positive Tinel test is defined as pain and/or paresthesia of the median-innervated fingers that occurs with percussion over the median nerve

Question 27

Who is electrodiagnostic testing reserved for in the context of CTS?

Answer 27

• We perform electrodiagnostic testing for CTS for all patients with atypical symptoms to confirm the diagnosis and for patients with symptoms that are moderate to severe or that progress despite conservative treatment to aid in decisions regarding surgical intervention
• If in doubt of diagnosis

Question 28

Use of EMG in CTS

Answer 28

• EMG is a useful component of electrodiagnostic testing in CTS to exclude other conditions, such as polyneuropathy, plexopathy, and radiculopathy, and to assess severity of CTS if surgical decompression is being considered
• EMG is not necessary for patients who have classic signs and symptoms of CTS and confirmatory findings on NCS when there is no suspicion for other etiologies and surgery is not contemplated

Question 29

Pathophysiology of carpal tunnel

Answer 29

• Anatomic compression and inflammation are contributing mechanisms.
• Increased pressure in the carpal tunnel can injure the nerve directly, impair axonal transport, or compress vessels in the perineurium and cause median nerve ischemia