Carpal tunnel syndrome Flashcards
What forms the carpal tunnel anatomically?
The carpal tunnel is formed by the transverse carpal ligament superiorly and the carpal bones inferiorly
What passes through the carpal tunnel?
The median nerve, accompanied by the nine flexor tendons of the forearm musculature, must pass through this anatomic tunnel
Where do we tend to find an inflamed and compressed median nerve?
- 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
Gender effect on CTS
CTS is more frequent in females, with a female-to-male ratio of approximately 3:1
Prevalence of CTS
The estimated prevalence of CTS in the general population is 1 to 5 percent.
What are risk factor for carpal tunnel syndrome?
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
Occupations with high risk of developing CTS
Occupational categories with particularly high risk of CTS include production and manufacturing, office and administrative support, and food processing and preparation
What is carpal tunnel syndrome?
The complex of symptoms and signs brought on by compression of the median nerve as it travels through the carpal tunnel
What are clinical symptoms of carpal tunnel syndrome?
- 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
What are provoking features for carpal tunnel syndrome?
CTS symptoms are often provoked by activities that involve flexing or extending the wrist or raising the arms
What are severe manifestations of carpal tunnel syndrome?
- 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
Differential diagnosis of carpal tunnel syndrome
The most common disorder than can mimic CTS is cervical radiculopathy, particularly with C6 or C7 nerve root involvement
Why is thenar eminence sparred in carpal tunnel syndrome?
Palmar branch of the median nerve does not pass through the carpal tunnel, so its not affected
How can one confirm the diagnosis of CTS?
- 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
What can CTS severity be divided into?
Low. moderate, severe
Describe low CTS siverity symptoms
- 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
Describe moderate CTS severity symptoms
- 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
Describe severe CTS severity symptoms
- 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
What are available treatments for CTS?
- 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)
Which therapies should be avoided for CTS?
- NSAIDs and other oral medications (not effective)
- No benefit for diuretics or vitamin B6
- Electrical, magnetic, and laser therapy
- Perineural dextrose injections
Which patients are selected for surgery for CTS?
Moderate or severe symptoms and electrodiagnostic evidence of severe median nerve injury (denervation or axon loss)
What are clinical tests that can be performed on patients to determine if they have CTS?
- Phalen test (3rd)
- Tinel test (4th)
- Manual carpal compression (2nd)
- Hand elevation test (most accurate)
How is hand elevation test performed for CTS?
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.
How is phalen test performed?
- 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
Manual carpal compression procedure
- 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
Tilen test procedure
- 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
Who is electrodiagnostic testing reserved for in the context of CTS?
- 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
Use of EMG in CTS
- 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
Pathophysiology of carpal tunnel
- 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
