From the Guidelines
To assess for carpal tunnel syndrome, a clinical evaluation combined with electrophysiologic studies is the recommended approach, with ultrasound or MRI used occasionally to visualize the median nerve and surrounding structures, as supported by the most recent evidence 1. When evaluating a patient for carpal tunnel syndrome, it is essential to begin with a thorough history focusing on symptoms like numbness, tingling, or pain in the thumb, index, middle, and half of the ring finger, especially at night or with repetitive hand activities.
- A physical examination should include inspection for thenar muscle atrophy and several provocative tests, such as:
- Tinel's test by tapping over the median nerve at the wrist to elicit tingling in the affected fingers
- Phalen's test by having the patient flex both wrists maximally for 60 seconds to see if symptoms are reproduced
- The carpal compression test involves applying direct pressure over the carpal tunnel for 30 seconds
- Two-point discrimination and grip strength testing can help evaluate sensory and motor function. If clinical assessment suggests carpal tunnel syndrome, electrodiagnostic studies (nerve conduction studies and electromyography) can confirm the diagnosis by measuring median nerve conduction across the wrist, as stated in 1. However, according to the most recent study 1, ultrasound has been demonstrated to be highly sensitive and specific for the diagnosis of carpal tunnel syndrome, and may be used as a complementary test or as the confirmatory test of choice in some cases. Early diagnosis is crucial as treatment options range from conservative measures like wrist splinting and activity modification to corticosteroid injections or surgical release for more severe cases.
From the Research
Assessment of Carpal Tunnel Syndrome
To assess for carpal tunnel syndrome, several methods can be employed, including:
- History taking
- Physical examination maneuvers
- Electrodiagnostic testing
Physical Examination Maneuvers
The following physical examination maneuvers can be used to assess for carpal tunnel syndrome:
- Tinel's sign: however, its usefulness is debated, with some studies suggesting it is not useful in the evaluation of patients with carpal tunnel syndrome 2
- Phalen's test: has a greater sensitivity and specificity compared to Tinel's sign, and can be of use in the diagnosis of carpal tunnel syndrome 2
- Hand elevation test: may be used in isolation and is superior to questionnaires and other physical signs in the clinical diagnosis of carpal tunnel syndrome 3
- Carpal compression test: can be used in combination with other tests, such as the tourniquet and Phalen's tests, to diagnose carpal tunnel syndrome 3
- Reverse Phalen's test: has a higher sensitivity and specificity for the diagnosis of tenosynovitis than for the diagnosis of carpal tunnel syndrome 4
Diagnostic Criteria
The American Academy of Neurology clinical diagnostic criteria can be used to diagnose carpal tunnel syndrome 4. Additionally, the following findings can be used to distinguish between patients with electrodiagnostic evidence of carpal tunnel syndrome and those without:
- Hypalgesia in the median nerve territory
- Classic or probable Katz hand diagram results
- Weak thumb abduction strength 5
Limitations
The utility of these results is limited by problems inherent in using nerve conduction studies as a criterion standard 5. Furthermore, the diagnosis of carpal tunnel syndrome can be challenging due to differentials that present with overlapping symptoms 6.