Differential Diagnosis
The following local conditions also cause hand and wrist complaints and must be ruled out before a diagnosis of Carpal Tunnel Syndrome is made:
- Tendon/ligament strain
- Tendonitis/tenosynovitis (this may be a co-existing condition or possible cause of Carpal Tunnel Syndrome)
- Hand-arm vibration syndrome
- Nerve or nerve root compression
- Non-specific hand/wrist pain
Numbness predominantly in the fifth finger or extending to the hypothenar eminence or dorsum of the hand should suggest diagnoses other than Carpal Tunnel Syndrome.
Examination Based Clinical Diagnosis
Paresthesias, hypoesthesia or numbness localized to the palmar aspect of the first to the fourth fingers and the distal palm (the sensory distribution of the median nerve at the wrist) are considered essential to make a clinical diagnosis of Carpal Tunnel Syndrome, although these symptoms are not specifically diagnostic of Carpal Tunnel Syndrome: other conditions may cause identical symptoms.
There is insufficient evidence to identify a single "best" physical examination-based test. The reliability and accuracy of the following clinical diagnostic tools appear to support their use as components of an examination-based clinical diagnosis of Carpal Tunnel Syndrome:
- Phalen Sign
- Carpal Compression Test (CCT or Durkan)
- Hand Symptom Diagram (HSD)
- Tinel Sign
It should be noted that both history and physical examination rely on subjective reporting of symptoms, sensation or pain: with the exception of thenar wasting, there are no objective examination-based clinical tests for median nerve impairment.
Electrodiagnostic Studies
Electrodiagnostic studies (EDS), including Nerve Conduction Studies (NCS) and electromyography (EMG) are the most objective tests available to demonstrate median nerve deficit.
Correlated with the history and physical examination, electrodiagnostic studies increase or decrease the probability of carpal tunnel syndrome as the correct diagnosis (use of electrodiagnostic study findings as the sole diagnostic tool is not recommended).
In the absence of thenar atrophy, bilateral upper limb electrodiagnostic studies are required to confirm a pre-operative diagnosis of Carpal Tunnel Syndrome.
Sensory Tests
Sensory tests for Carpal Tunnel Syndrome (such as Semmes-Weinstein) typically involve measurement of a patient's threshold for detection of a sensory stimulus. There is little evidence to support use of sensory tests for diagnosis of Carpal Tunnel Syndrome.
Imaging Tests
The potential utility of computed tomography, magnetic resonance imaging and ultrasonography in Carpal Tunnel Syndrome diagnosis is still being determined and they remain primarily research tools.
Laboratory and Other Tests
