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Diagnostic Features
Carpal Tunnel Syndrome
Introduction
Carpal Tunnel Syndrome (CTS) is the most common entrapment neuropathy involving the upper extremity. The estimated prevalence of CTS in the general population is about 3%. CTS predominates in women with a female to male ratio of approximately 3 to 1. It has a peak age range of 40 to 60 years. It can be unilateral or bilateral on presentation.
The carpal tunnel is a passageway in the wrist bordered by the transverse carpal ligament (flexor retinaculum) superiorly, and the carpal bones inferiorly. The median nerve and nine flexor tendons of the forearm muscles pass through the tunnel.
Carpal Tunnel Syndrome arises through increased pressure within the carpal tunnel resulting in compression and damage to the median nerve. This damage is thought to progress from initial demyelination to axonal degeneration. It is believed that the sensory fibers are typically affected first followed by motor fibers. In addition, autonomic nerve fibers within the nerve may be affected.
Risk factors for the development of Carpal Tunnel Syndrome include:
- Hand activities that require a high degree of repetition and force
- Obesity
- Diabetes mellitus
- Hypothyroidism
- Pregnancy
- Rheumatoid arthritis
- Congenitally small and/or square-shaped wrists
- Wrist fracture, carpal dislocation, or other severe injuries to the wrist
- Space-occupying lesions within the tunnel (e.g., ganglions or tumors)
- Local or systemic edema
Nerve Conduction Studies and Surgical Considerations
Patients with severe Carpal Tunnel Syndrome signs and symptoms need to be referred for medical evaluation. In some patients, nerve conduction studies are required to confirm the diagnosis and the severity of Carpal Tunnel Syndrome to determine potential surgical considerations.
History
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Start Yearly Plan- Pain or paresthesia (numbness and tingling) in the palmar surface of the lateral three digits and the radial half of the fourth
- A dull aching discomfort in the hand which may extend to the forearm or the upper arm
- Nocturnal symptoms that often awaken the patient
- Symptoms may be relieved by shaking the hand (“Flick Sign”) or placing the hand under warm running water
- Symptoms are often provoked by activities that involve repetitious flexion or extension the wrist
- Weakness (e.g., difficulty holding objects or opening jars), easy fatigability, or clumsiness (e.g., difficulty when buttoning a shirt) in the involved hand
- Patients may report a sensation of swelling in the hand which is not found on inspection
- Patients may report the hand feeling hot or cold or report sensitivity to changes in temperature (particularly to cold)
Physical Examination
- Sensory loss is typically found over the median nerve distribution in the anterior aspect of the hand involving the thumb, and the lateral three and a half fingers. The thenar eminence is typically spared.
- In advanced and severe cases, atrophy of the thenar eminence and weakness of thumb abduction and opposition may be present.
- Positive Phalen’s and Carpal Compression tests.
- Positive Tinel’s Sign on percussion over the flexor retinaculum.
Imaging
Plain radiography may be useful in detecting underlying bone or joint disease.
Diagnostic ultrasound is helpful in measuring the size of the median nerve which closely correlates with Carpal Tunnel Syndrome severity. It is also helpful in evaluating underlying causes such as tenosynovitis and space-occupying lesions.
Nerve conduction studies may be used to confirm Carpal Tunnel Syndrome by detecting impaired conduction across the carpal tunnel while finding normal conduction elsewhere.
Magnetic Resonance Imaging is usually reserved for detecting space-occupying lesions.
Laboratory blood tests may be necessary for investigating the presence of comorbidities (e.g., diabetes or hypothyroidism) when other signs and symptoms are present.
Red Flags
The following are examples of “red flags” for patients presenting with neuromusculoskeletal pain:
- History of a significant injury
- Severe pain
- Unrelenting pain
- Nocturnal pain or pain at rest
- Unexplained weight loss
- Fever
- Deformity
- Large joint swelling
- Significant loss of range of motion
- Significant neurological impairment
- Severe tenderness on palpation or severe pain with any examination procedure
If any “red flags” are identified during history taking and clinical examination, referral for urgent medical evaluation and further investigation is warranted.
Clinical Tips
Anterior Hand, Wrist, and Forearm Pain
The differential diagnosis of anterior hand, wrist, and forearm pain should include a number of other conditions such as:
- Pronator teres syndrome
- Myofascial pain syndrome of the palmaris longus, pronator teres, flexor carpi radialis, and flexor digitorum superficialis muscles
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